HomeMy WebLinkAbout2022-01-04; Beach Preservation Commission; ; City Council Position Statement regarding the City of Oceanside’s planned Beach Sand Replenishment and Retention Device ProjectMeeting Date: Jan. 4, 2022
To: Beach Preservation Commission
From: Kyle Lancaster, Parks & Recreation Director
Staff Contact: Michael Tully, Parks Planner
Subject: City Council Position Statement regarding the City of Oceanside’s
planned Beach Sand Replenishment and Retention Device Project
Recommended Action
Recommend the City Council adopt a resolution approving the City Council’s Position Statement
of opposition to the City of Oceanside’s planned Beach Sand Replenishment and Retention
Device Project and directing staff to send a copy of the resolution to the Oceanside City Council.
Background
On Aug. 26, 2021, the City Council received a Council Memorandum on the ‘Status of City of
Oceanside’s Beach Sand Replenishment and Retention Device Project’ (Exhibit 1). At the
conclusion of that memo, staff indicated it would provide periodic updates on the project to the
Beach Preservation Commission and the City Council.
Discussion
On Oct. 9, 2019, the Oceanside City Council directed staff to initiate a process to identify
feasible solutions to protect the Oceanside coastline from erosion by either utilizing re-
nourishment projects of beach suitable sands, construction of retention devices to reduce the
loss of sand, or a combination of both. The goal was to identify strategies that were
environmentally sensitive, financially feasible, and that had a reasonable chance of being
approved through the regulatory permitting process.
In April 2020, the Oceanside City Council approved a professional services agreement with
engineering consultant GHD, which then worked on a study evaluating alternatives to stabilize
and enhance the beach widths within the City of Oceanside. On Aug. 11, 2021, the resulting
Beach Sand Replenishment and Retention Device Project Feasibility Analysis and an
accompanying staff report were presented to the Oceanside City Council at a workshop. The
study area spanned the coastline from Camp Pendleton to the Agua Hedionda Lagoon.
Section 2., Coastal Setting, of the analysis document, states in part:
The wave climate within the City is characterized by seasonal long-period swells
generated by distant storms in the North Pacific and Southern Oceans. Southern swell
arrives at Oceanside from the southwest through the spring and summer months and
Jan. 4, 2022 Item 4 Page 1 of 229
transports sand to the north (Figure 2-1). Larger North Pacific swell[s] approaching from
the northwest and west during the fall and winter months transports sand to the south
(Figure 2-2). Locally generated short-period wind waves can occur any time during the
year and typically come from the west.
Waves are the dominant driver of sediment transport along Oceanside beaches. The net
longshore sediment transport patterns for Oceanside are accepted to be southern,
although seasonal variations are common and depend on the swell direction. There are
numerous estimates of the longshore sediment transport for Oceanside and within the
Oceanside Littoral Cell, as shown in Table 2.1. These estimates are based on historic
studies and have not been updated or field verified recently. However, amongst these
studies there is general agreement that Oceanside experiences a net sediment transport
to the south of 100,000 to 200,000 cubic yards (cy) per year.
GHD estimated the cost and the approach of future phases of the project and engaged the
Center for Climate Change Impacts and Adaptation at the Scripps Institute of Oceanography to
develop a scientific coastal baseline and monitoring plan. GHD also performed numerical
modeling to predict how the alternatives would impact local and regional sand movement.
Additionally, several resource agency, stakeholder, and other meetings were conducted to
understand any concerns and receive feedback on the alternatives being considered. However,
the City of Carlsbad was not directly consulted by the City of Oceanside staff, nor by GHD, as a
stakeholder during the referenced period of input. City of Carlsbad staff were also not
informed of any public meetings held to review and comment on the analysis.
Four alternatives for sand retention were outlined at the Aug. 11, 2021 Oceanside City Council
workshop. Additionally, three sand distribution or bypass options were reviewed for their
applicability and utility in resolving the erosion issues within the city. Of the four retention
alternatives studied, groins were ranked the highest - based on the multi-criterion analysis of
technical performance, financial analysis, and environmental consideration. The analysis
document recommended a pilot project consisting of groins and a sand bypass system. The
project area spanned the coastline from the Oceanside Pier to the Buena Vista Lagoon.
The Oceanside City Council voted to initiate the pilot project and directed staff to begin the
associated design, permitting and environmental work. Mayor Sanchez, casting the lone
dissenting vote, expressed doubt that the California Coastal Commission (Coastal Commission)
would approve the permits that would be necessary for the pilot project to move forward. The
Mayor, who previously served as a Coastal Commissioner, did not support the expenditure of
funds on pursuing the design, permitting and environmental review of this alternative,
considering it was unlikely to receive Coastal Commission approval because it interferes with
the natural flow of sand down the coast. Mayor Sanchez instead favored the beach
nourishment alternative.
The City of Oceanside’s intended approach of the groin alternative was that it would be
“adaptable and reversable,” based on the results of scientific monitoring programs. The pilot
Jan. 4, 2022 Item 4 Page 2 of 229
project would consist of four groins. Presuming sand retention success is achieved with those
groins, more groins may be added to other sections of the Oceanside coastline in future phases.
On Oct. 20, 2021, the City of Oceanside publicly advertised a “Request for Proposals (RFP) for
the Design, CEQA/NEPA Documentation & Permitting Phase for the Oceanside Sand Retention
Project.” The RFP description reads in part:
The City of Oceanside’s Public Works Department is seeking Proposals from qualified
firms specializing in coastal engineering ("Consultant") with experience in the design and
permit processing of coastal engineering projects in the Southern California’s coastal
zone, including extensive experience with community/stakeholder engagement efforts
for large-scale, complex projects, preparation of CEQA/NEPA documents, and securing
appropriate permits from all responsible agencies.
The advertised due date for firms to submit proposals was Dec. 7, 2021. The Oceanside City
Council has not yet entered into an agreement with a qualified firm. Once a firm is selected
and an agreement is executed, the next phase of the project is expected to take approximately
two years to complete. The City of Oceanside staff plans to work with GHD to conduct
additional public outreach in this next phase of the project, before the final groin locations are
determined. Key agency stakeholder coordination and engagement is also anticipated to occur
with entities such as the California Coastal Commission, Camp Pendleton and Surfrider
Foundation. During the project permitting and environmental review process, it is anticipated
there will be opportunities for the City of Carlsbad, and other southerly municipalities, to
provide comments on the potential impacts from this project.
Next Steps
Should the Carlsbad City Council vote in favor of the recommended action, staff will send a
letter to the Oceanside City Council, transmitting the Carlsbad City Council resolution approving
a position statement in opposition to the City of Oceanside’s planned Beach Sand
Replenishment and Retention Device Project. Staff will also continue to monitor the permitting
and environmental review process and will provide comments on the project as opportunities
become available.
Exhibits
1.City of Oceanside Staff Report and Beach Sand Replenishment and Retention Device
Feasibility Analysis, dated Aug. 11, 2021
Jan. 4, 2022 Item 4 Page 3 of 229
CITY COUNCIL
AGENDA
MAYOR AND COUNCIL WORKSHOP
August 11, 2021
2:00 p.m.
ADJOURNED MEETING City Council Chambers
300 North Coast Highway
CALL TO ORDER
PLEDGE OF ALLEGIANCE
ROLL CALL
WORKSHOP ITEMS:
1.City Council: Approval of the Beach Sand Feasibility Study Report and direction to staff to move
to the next phase of the project to include design, permitting, and environmental work for a groin
and bypass system pilot project
A)Report by Kiel Koger, Public Works Director
B)Discussion
C)Recommendation – approve the report and provide direction to staff
2.Public Communication on City Council Matters (off-agenda items)
ADJOURNMENT
The next regularly scheduled meeting is at 3:30 p.m. on Wednesday, August 18, 2021.
AGENDA POSTING AND MATERIALS
The agenda has been posted at least 72 hours prior to the meeting at the Civic Center Plaza, 300 North
Coast Highway. The agenda may also be inspected at the City Clerk’s Office at 300 North Coast Highway.
Persons requiring assistance or auxiliary aids in order to participate may contact the City Clerk at 300
North Coast Highway, Oceanside, CA, telephone (760) 435-3000 at least 24 hours prior to the meeting.
Jan. 4, 2022 Item 4 Page 4 of 229
Exhibit 1
2
CITY OF OCEANSIDE
AGENDA
Joint Meetings of the Oceanside City Council,
Oceanside Small Craft Harbor District Board of Directors,
Oceanside Community Development Commission, and
Oceanside Public Financing Authority
Special Advisory for the August 11, 2021 City Council Workshop
This workshop will be conducted in accordance with Governor Newsom’s Executive Order 29-20 relating
to the COVID-19 virus. That order, effective until October 1, 2021, suspends several provisions of the
Brown Act related to telephonic participation by the City Council, staff members and the public. Members
of the public have the option to watch the workshop on KOCT Cox Channel 19 (live streaming service
available at www.koct.org/channel-19) or participate online via Zoom or attend in person. Members of
the public who attend the meeting in person and are unvaccinated are requested to wear facial coverings
in City facilities.
Zoom Participation:
Members of the public can watch or participate in the meeting through Zoom. To join the meeting from a
PC, Mac, iPad, iPhone, or Android device, please click this URL: https://us02web.zoom.us/j/81663275824
Please make sure you are muted and your video is turned off when you join the meeting.
Phone Participation:
To join the meeting by phone, dial 669-900-6833.
Webinar ID: 816 6327 5824
Please make sure you are muted when you join the meeting.
If you would like to speak on an agenda item during the workshop via Zoom, you must email the City
Clerk (CityClerk@OceansideCA.org) by 1 PM on August 11, 2021. Please provide the City Clerk your name
and the item number you wish to comment on. If you plan to call into the meeting, you must also provide
the telephone number you will be using. You must be logged on to the Zoom meeting by phone or online
to speak. When it is your turn to comment, the City Clerk will call you by name or phone number.
If you wish to provide a comment to the City Council, but are not interested in speaking during the
workshop, you may email your comments to the City Clerk (CityClerk@OceansideCA.org). All comments
must be sent via email by 1 PM on the day of the workshop. All timely received comments will be
provided to the City Council prior to the workshop and made a part of the record. Please note that
these comments will not be read aloud during the meeting.
If you have special needs because of a disability which makes it difficult for you to submit comments
telephonically or through use of Zoom, please contact the City Clerk at (760) 435-3001 by 12 PM
Monday, August 9, 2021, to make arrangements to accommodate your disability.
Jan. 4, 2022 Item 4 Page 5 of 229
ITEMNO.1CIIYOFOCEANSIDEiSTAFFREPORTDATE:August11,2021TO:HonorableMayorandCityCouncilmembersFROM:PublicWorksDepartmentSUBJECT:BEACHSANDFEASIBILITYSTUDYREPORTANDDIRECTIONTOSTAFFSYNOPSISStaffrecommendsthattheCityCouncilapprovetheBeachSandFeasibilityStudyReportanddirectstafftomovetothenextphaseoftheprojecttoincludedesign,permitting,andenvironmentalworkforagroinandbypasssystempilotproject.BACKGROUNDOceansidehasa79-yearhistoryofbeacherosionresultingfromtheCampPendletonHarborconstructionin1942.Thefederalgovernmentfirstidentifiedtheerosionproblemandacknowledgedsoleresponsibilityforthisissuein1953.NumerousreportsandstudieshavebeenconductedovertheyearsbytheArmyCorpsofEngineers(Corps).SANDAG,andcoastalengineeringfirmstostudytheproblem.In2000,theCorpswasdirectedbyCongressthroughtheWaterResourcesDevelopmentAct(Act)toconductaSpecialShorelineFeasibilityStudy(Study)with100percentFederalfundingandcompletetheStudywithin44monthsafterthedatetheActwasenacted.TheStudywasintendedtoidentifysolutionstomitigatebeacherosionandotherimpactsresultingfromtheconstructionofCampPendletonHarborandtorestorebeachconditionsalongtheaffectedpublicandprivateshorestotheconditionsthatexistedbeforetheconstructionofCampPendletonHarbor.Todate,theStudyhasnotbeencompleteddueto alackofFederalfunding.DuetotheinabilityoftheCorpstocompletetheStudyandperdirectiongivenbytheCityCouncilatitsOctober9.2019.meeting.staffinitiatedaprocesstoidentifyfeasiblesolutionstoprotectthebeachfromlong-termerosionbyeitherutilizingre-nourishment.projectsofbeachsuitablesands.constructionofretentiondevicestoretain/reducethelossofsand.oracombinationofboth.Thegoalwastoidentifystrategiesthatareenvironmentallysensitive,financiallyfeasible,andthathaveareasonablechanceofbeingapprovedthroughtheregulatorypermittingprocess.Jan. 4, 2022Item 4 Page 6 of 229
ANALYSISinNovember2019,theCitysolicitedproposalsfromqualifiedconsultingfirmsspecializingincoastalengineeringtoprovideapreliminaryengineeringevaluationandfeasibilitystudyforabeachsandreplenishmentandretentiondeviceproject.Fivefirmssubmittedproposals,whichwerereviewedbasedontheapproachtotheevaluationandstudy,previousexperiencewithsimilarstudies,qualificationsofteammembers,satisfactionofpreviousclients.overallunderstandingoftheproject,andtheabilitytoprovideaqualityproductinthetimeframeallotted.ThreefirmswereshortlistedandapanelofCitystaffconductedinterviewsinJanuary2020.Thepaneldeterminedthetop-rankedfirmtobeGHDandstaffenteredintoanegotiationprocess,resultinginaProfessionalServicesAgreementwhichwasapprovedbytheCityCouncilonApril8,2020.GHDworkedonthestudyforapproximatelyoneyearwhileevaluatingoptionstostabilizeandenhancethebeachwidthsintheCity.Theyperformednumeroustasksduringthestudy,includingareviewofpertinentstudiesanddatatodevelopamorein-depthunderstandingoftheshoreline'sconditionandhowpastprojectshaveperformedinotherareas.Theyreviewedandanalyzedrelevantglobalprojectexamples,aswellasdevelopedsixpreliminaryconceptstocarryforward,includingthreereplenishmentandthreeretentionoptionsforevaluation.GHDalsoestimatedcostandapproachforfutureprojectphasesforselectedoptionsandengagedtheCenterforClimateChangeImpactsandAdaptation(CCIA)attheScrippsInstituteofOceanography(SIO)todevelopascientificcoastalbaselineandmonitoringplan.Theyalsoperformednumericalmodelingofoptionstopredicthowtheoptionsbeingconsideredwillimpactlocalandregionalsandmovement,aswellasconductedseveralresourceagency,stakeholder,andothermeetingstounderstandconcernsandreceivefeedbackonoptionsbeingconsidered.Aconsiderableamountofoutreachwasdoneduringthepastyear,includingvirtualmeetingswiththepublic,CaliforniaCoastalCommission,RegionalWaterQualityControlBoard,ArmyCorpsofEngineers,SurfriderFoundation,SANDAGShorelinePreservationWorkingGroup,ResilientCitiesCatalysts,aswellasinterestedadvocacygroups,homeowners,andconcernedcitizens.Afterasubstantialamountofresearch,modeling,andanalysis,themostpracticaloptionthatmettheabove-mentionedprojectgoalswasdeterminedtobetheuseofgroinsforsandretentionwithabypasssystemforreplenishment.Eachoptionwasrunthroughamulti-criteriadecisionmatrixtoconsiderdowndriftimpacts,surfingimpacts,nearshorereefimpacts,aestheticimpacts,sealevelriseresilience,estimatedconstructioncostsandlifecyclecosts.Staffrecommendsthattheprojectmovetowardtothenextphase(i.e.,design,permitting,andenvironmentalwork)ofapilotprojectconsistingofgroinsandabypasssystem.Thisphaseisanticipatedtocost$1million.Theideaistobeginwithapilotproject,then,assumingsuccessoftheproject,addmoregroinsonanas-neededbasistoothersectionsofthecoastlineinfuturephases.GHD'sreportsuggestsfourgroinsinitiallybuttheexactnumber,length,andlocationwillneedtobeaddressedinthenextphaseoftheprojectwithmorepublicoutreach.TheCitywillalsoneedtoestablishasecure,significantsourceofhigh-qualitysandbeforedesignofabypasssystem.StaffandGHDhaveidentifiedanideal2Jan. 4, 2022Item 4 Page 7 of 229
sandsource(thefilletatDelMarBeachonCampPendleton)andareintheprocessofcreatinganagreement,whichwillneedtobefinalizedbeforeproceedingwithdesignofthebypasssystem.OnJune30.2021,staffhostedawell-attendedpublicworkshoptosharetheresultsoftheBeachSandReplenishment/RetentionFeasibilityStudy.Whilesomeattendeesexpressedconcernsovertheproposeduseoftheretentiondevices,themajorityofthepubliccommentsreceivedatthisworkshopwereinfavorofagroinsystemasthepreferredoption.PubliccommentsreceivedatthismeetingsuggestedgroinlocationsatthesouthernendoftheCity.ratherthantheoriginallysuggestedlocationsofMarronStreetandTysonStreet.StaffplanstoworkswithGHDtoconductadditionalpublicoutreachinthenextphaseoftheprojectbeforefinallocationsaredecided.IftheCityCouncilapprovesstaff'srecommendation,staffwillissueanRFPforthenextphaseoftheproject,whichincludesdesign,permitting,andenvironmentalwork.Onceaconsultantisselected.thisphaseoftheprojectisexpectedtotakeapproximatelytwoyears.FISCALIMPACTNoFiscalImpact.Thenextphaseoftheprojectisestimatedat$1Mandstaffwillpresentfundingoptionsforthisphaseatalaterdate.INSURANCEREQUIREMENTSDoesnotapply.COMMISSIONORCOMMITTEEREPORTDoesnotapply.CITYATTORNEY’SANALYSISThereferenceddocumentshavebeenreviewedbytheCityAttorneyandapprovedastoform.Jan. 4, 2022Item 4 Page 8 of 229
RECOMMENDATIONStaffrecommendsthattheCityCouncilapprovetheBeachSandFeasibilityStudyReportanddirectstafftomovetothenextphaseoftheprojecttoincludedesign,permitting,andenvironmentalworkforagroinandbypasssystempilotproject.PREPAREDBY:SUBMITTEDBY:L11cmMKieoger’eannaLorsonPuWorksDirectorCityManagerREVIEWEDBY:JonathanBorrego,DeputyCityManagerBrianThomas,CityEngineerRussCunningham,PrincipalPlannerECAttachment:BeachSandFeasibilityStudyReportJan. 4, 2022Item 4 Page 9 of 229
City of Oceanside Beach Sand
Replenishment and Retention Device
Project
DRAFT
Feasibility Analysis of Project Alternatives
Prepared for:
City of Oceanside
Public Works Department
June 2021
(Photo: SANDAG 2020)
Attachment61:9
City of Oceanside Beach Sand
Replenishment and Retention Device
Project
DRAFT
Feasibility Analysis of Project Alternatives
ye:i.3'2 *,
Prepared for:
City of Oceanside
Public Works Department
June 2021
Jan. 4, 2022 Item 4 Page 10 of 229
GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page i
Table of Contents
ES.1 Executive Summary ....................................................................................................................... 1
1. Introduction ................................................................................................................................... 8
2. Coastal Setting ........................................................................................................................... 11
3. Historical Perspective ................................................................................................................. 14
3.1 Chronology of Coastal Development & Human Interventions ......................................... 14
3.2 Oceanside Harbor Maintenance Dredging Program ....................................................... 15
3.3 Regional Beach Sand Projects ........................................................................................ 18
3.4 Shoreline Changes .......................................................................................................... 18
3.4.1 North Oceanside ............................................................................................. 19 3.4.2 South Oceanside ............................................................................................ 20 3.4.3 North Carlsbad ................................................................................................ 21
4. Synthesis of Coastal Challenges ............................................................................................... 23
4.1 Oceanside Harbor Complex & Sediment Gradation ........................................................ 23
4.2 Limited Beach Gains from USACE Harbor Dredging Program ....................................... 24
4.3 Poor Performance of Regional Beach Fills ...................................................................... 27
4.1 Difficulty Reaching Social, Political & Regulatory Consensus ......................................... 31
5. Data Review and Assimilation .................................................................................................... 32
5.1 Coastal Studies ................................................................................................................ 32
5.2 Sand Bypassing Project Examples .................................................................................. 33
5.3 Sand Retention Project Examples ................................................................................... 34
6. Alternatives ................................................................................................................................. 35
6.1 Pilot Approach .................................................................................................................. 35
6.2 No Project ........................................................................................................................ 35
6.3 Alternative 1: Beach Nourishment ................................................................................... 36
6.4 Alternative 2: Groins ........................................................................................................ 36
6.5 Alternative 3: San Luis Rey Groin Extension ................................................................... 36
6.6 Alternative 4: Multi-Purpose Artificial Reef ...................................................................... 37
7. Other Alternatives Considered ................................................................................................... 43
8. Numerical Modeling of Alternatives ............................................................................................ 44
8.1 Model Description ............................................................................................................ 44
8.2 Calibration and Validation ................................................................................................ 46
8.3 LITPACK Sand Retention Device Modeling .................................................................... 46
8.3.1 Full-scale Model Results ................................................................................ 46 [Q]Table of Contents
ES.1 Executive Summary.......................................................................................................................1
1 .Introduction ...................................................................................................................................8
2.Coastal Setting ...........................................................................................................................1 1
3.Historical Perspective .................................................................................................................14
3.1 Chronology of Coastal Development &Human Interventions .........................................14
3.2 Oceanside Harbor Maintenance Dredging Program .......................................................15
3.3 Regional Beach Sand Projects ........................................................................................18
3.4 Shoreline Changes ..........................................................................................................18
3.4.1 North Oceanside .............................................................................................19
3.4.2 South Oceanside ............................................................................................20
3.4.3 North Carlsbad ................................................................................................21
4.Synthesis of Coastal Challenges ...............................................................................................23
4.1 Oceanside Harbor Complex &Sediment Gradation ........................................................23
4.2 Limited Beach Gains from USACE Harbor Dredging Program .......................................24
4.3 Poor Performance of Regional Beach Fills ......................................................................27
4.1 Difficulty Reaching Social,Political &Regulatory Consensus .........................................31
5.Data Review and Assimilation ....................................................................................................32
5.1 Coastal Studies ................................................................................................................32
5.2 Sand Bypassing Project Examples ..................................................................................33
5.3 Sand Retention Project Examples ...................................................................................34
6.Alternatives .................................................................................................................................35
6.1 Pilot Approach ..................................................................................................................35
6.2 No Project ........................................................................................................................35
6.3 Alternative 1:Beach Nourishment ...................................................................................36
6.4 Alternative 2:Groins ........................................................................................................36
6.5 Alternative 3:San Luis Rey Groin Extension ...................................................................36
6.6 Alternative 4:Multi-Purpose Artificial Reef ......................................................................37
7.Other Alternatives Considered ...................................................................................................43
8.Numerical Modeling of Alternatives............................................................................................44
8.1 Model Description ............................................................................................................44
8.2 Calibration and Validation ................................................................................................46
8.3 LITPACK Sand Retention Device Modeling ....................................................................46
8.3.1 Full-scale Model Results ................................................................................46
GHD |Beach Sand Replenishment &Retention Device Project |June 2021 |Page iJan. 4, 2022 Item 4 Page 11 of 229
GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page ii
8.3.2 Pilot-scale Results - Groin Field ..................................................................... 49 8.3.3 Pilot-scale Results - Artificial Reef .................................................................. 51
9. Multi-Criteria Analysis................................................................................................................. 53
9.1 Alternative Analysis Criteria ............................................................................................. 53
9.1.1 Technical Performance ................................................................................... 53 9.1.2 Financial ......................................................................................................... 54 9.1.3 Environmental ................................................................................................. 54
9.2 Weighting and Scoring System ........................................................................................ 55
9.3 Results ............................................................................................................................. 56
9.3.1 Analysis of Technical Performance Criteria ................................................... 58 9.3.2 Analysis of Financial Criteria .......................................................................... 58 9.3.3 Analysis of Environmental Criteria.................................................................. 59
9.4 Sensitivity ......................................................................................................................... 60
9.4.1 Criteria Scoring Sensitivity .............................................................................. 60 9.4.2 Category Weighting Sensitivity ....................................................................... 61
10. Value Comparison, Beach Nourishment vs Sand Retention ..................................................... 63
11. Sand Management Systems Evaluation .................................................................................... 64
11.1 Fixed Trestle Sand Bypass .............................................................................................. 65
11.2 Semi-fixed Sand Bypass .................................................................................................. 68
11.3 Piggyback on USACE Harbor Dredging Program ........................................................... 70
11.4 Comparison of Sand Distribution Systems ...................................................................... 72
12. Conclusions ................................................................................................................................ 74
13. Next Steps .................................................................................................................................. 76
14. References ................................................................................................................................. 78
Figure Index
Figure 1-1. Project Location ................................................................................................................... 9
Figure 1-2. Project Area ....................................................................................................................... 10
Figure 2-1. Summer Wave Height and Approach Direction (CDIP Station 045 2000-2020) ............... 13
Figure 2-2. Winter Wave Height and Approach Direction (CDIP Station 045 2000-2020) .................. 13
Figure 3-1. Fixed Sediment Bypass Pilot ............................................................................................. 15
Figure 3-2. USACE Harbor Dredging Sand Placement Locations (USACE 2020) .............................. 17
Figure 3-3. Oceanside Harbor Annual Dredge Volumes from 1942-2020 ........................................... 18
Figure 3-4. Historical Shoreline Positions in the City (USACE 2015) .................................................. 19
Figure 3-5. Fall 2017 Photograph looking south from Buccaneer Beach ............................................ 20 [Q]10.
11.
12.
13.
14.
8.3.2 Pilot-scale Results -Groin Field .....................................................................49
8.3.3 Pilot-scale Results -Artificial Reef..................................................................51
Multi-Criteria Analysis.................................................................................................................53
9.1 Alternative Analysis Criteria .............................................................................................53
9.1.1 Technical Performance ...................................................................................53
9.1.2 Financial .........................................................................................................54
9.1.3 Environmental .................................................................................................54
9.2 Weighting and Scoring System ........................................................................................55
9.3 Results .............................................................................................................................56
9.3.1 Analysis of Technical Performance Criteria ...................................................58
9.3.2 Analysis of Financial Criteria ..........................................................................58
9.3.3 Analysis of Environmental Criteria..................................................................59
9.4 Sensitivity .........................................................................................................................60
9.4.1 Criteria Scoring Sensitivity ..............................................................................60
9.4.2 Category Weighting Sensitivity .......................................................................61
Value Comparison,Beach Nourishment vs Sand Retention .....................................................63
Sand Management Systems Evaluation ....................................................................................64
11.1 Fixed Trestle Sand Bypass ..............................................................................................65
11.2 Semi-fixed Sand Bypass..................................................................................................68
11.3 Piggyback on USACE Harbor Dredging Program ...........................................................70
11.4 Comparison of Sand Distribution Systems ......................................................................72
Conclusions ................................................................................................................................74
Next Steps ..................................................................................................................................76
References .................................................................................................................................78
Figure Index
Figure 1-1.Project Location ...................................................................................................................9
Figure 1-2.Project Area .......................................................................................................................10
Figure 2-1.Summer Wave Height and Approach Direction (CDIP Station 045 2000-2020)...............13
Figure 2-2.Winter Wave Height and Approach Direction (CDIP Station 045 2000-2020)..................13
Figure 3-1.Fixed Sediment Bypass Pilot .............................................................................................15
Figure 3-2.USACE Harbor Dredging Sand Placement Locations (USACE 2020)..............................17
Figure 3-3.Oceanside Harbor Annual Dredge Volumes from 1942-2020 ...........................................18
Figure 3-4.Historical Shoreline Positions in the City (USACE 2015)..................................................19
Figure 3-5.Fall 2017 Photograph looking south from Buccaneer Beach ............................................20
GHD |Beach Sand Replenishment &Retention Device Project |June 2021 |Page iiJan. 4, 2022 Item 4 Page 12 of 229
GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page iii
Figure 3-6. Profile Location Map and Shoreline Change Trends in Study Reach ............................... 22
Figure 4-1. Comparison of Beach Type and Gradation North and South of Oceanside Harbor.......... 24
Figure 4-2. USACE Sand Placement Relative to Seasonal Longshore Transport Schematic ............ 25
Figure 4-3. Relationship between Native and Beach Fill Grain Size and Beach Performance (derived from
Dean, 1991) ..................................................................................................................... 26
Figure 4-4. Current USACE Placement Methods ................................................................................. 27
Figure 4-5. Post RBSP II Shoreline Positions ...................................................................................... 29
Figure 4-6. RBSP II Performance at South Oceanside ........................................................................ 30
Figure 5-1. Recommended Groin Concept (USACE, 1980) ................................................................ 33
Figure 6-1. Beach Nourishment Concept ............................................................................................. 38
Figure 6-2. Groin Field Concept ........................................................................................................... 39
Figure 6-3. San Luis Rey Groin Extension Concept ............................................................................ 40
Figure 6-4. Multi-Purpose Artificial Reefs Concept .............................................................................. 41
Figure 6-5. Multi-Purpose Artificial Reefs Concept - Reef Detail ......................................................... 42
Figure 8-1. Numerical Modeling Domain .............................................................................................. 45
Figure 8-2. Full-scale model results (simulated 2015 shoreline position) ............................................ 48
Figure 8-3. Modeled Shoreline Change for Groin Pilot ........................................................................ 50
Figure 8-4. Modeled Shoreline Change for Reef Pilot ......................................................................... 52
Figure 9-1 Sensitivity to Category Weighting ....................................................................................... 62
Figure 10-1. Illustration of MSL Beach Width vs. Dry Beach Width ..................................................... 63
Figure 10-2. Value Comparison for Each Alternative ........................................................................... 64
Figure 11-1. Fixed Trestle Sand Bypass Option .................................................................................. 67
Figure 11-2. Mobile Sand Bypass Option – Sandshifter Detail (Swash, 2021) ................................... 69
Figure 11-3. Mobile Sand Bypass Option – Indian River Inlet, Delaware (USACE, 2021) .................. 70
Figure 11-4. Piggyback on USACE Program Option – Sand Distribution System ............................... 71
Table Index
Table 2-1. Longshore Sediment Transport Estimates .......................................................................... 12
Table 3-1. Chronology of Coastal Development and Interventions in Oceanside ............................... 16
Table 9-1 Public Outreach – Poll Question Result ............................................................................... 53
Table 9-2 Technical Performance Criteria ........................................................................................... 54 [Q]Figure 3-6.Profile Location Map and Shoreline Change Trends in Study Reach ...............................22
Figure 4-1.Comparison of Beach Type and Gradation North and South of Oceanside Harbor..........24
Figure 4-2.USACE Sand Placement Relative to Seasonal Longshore Transport Schematic ............25
Figure 4-3.Relationship between Native and Beach Fill Grain Size and Beach Performance (derived from
Dean,1991).....................................................................................................................26
Figure 4-4.Current USACE Placement Methods.................................................................................27
Figure 4-5.Post RBSP ||Shoreline Positions ......................................................................................29
Figure 4-6.RBSP ||Performance at South Oceanside ........................................................................30
Figure 5-1.Recommended Groin Concept (USACE,1980)................................................................33
Figure 6-1.Beach Nourishment Concept.............................................................................................38
Figure 6-2.Groin Field Concept ...........................................................................................................39
Figure 6-3.San Luis Rey Groin Extension Concept ............................................................................40
Figure 6-4.Multi-Purpose Artificial Reefs Concept ..............................................................................41
Figure 6-5.Multi-Purpose Artificial Reefs Concept -Reef Detail .........................................................42
Figure 8-1.Numerical Modeling Domain ..............................................................................................45
Figure 8-2.Full-scale model results (simulated 2015 shoreline position)............................................48
Figure 8-3.Modeled Shoreline Change for Groin Pilot ........................................................................50
Figure 8-4.Modeled Shoreline Change for Reef Pilot .........................................................................52
Figure 9-1 Sensitivity to Category Weighting .......................................................................................62
Figure 10-1.Illustration of MSL Beach Width vs.Dry Beach Width .....................................................63
Figure 10-2.Value Comparison for Each Alternative ...........................................................................64
Figure 11-1.Fixed Trestle Sand Bypass Option ..................................................................................67
Figure 11-2.Mobile Sand Bypass Option —Sandshifter Detail (Swash,2021)...................................69
Figure 11-3.Mobile Sand Bypass Option —Indian River Inlet,Delaware (USACE,2021)..................70
Figure 11-4.Piggyback on USACE Program Option —Sand Distribution System...............................71
Table Index
Table 2-1.Longshore Sediment Transport Estimates ..........................................................................12
Table 3-1.Chronology of Coastal Development and Interventions in Oceanside ...............................16
Table 9-1 Public Outreach —Poll Question Result ...............................................................................53
Table 9-2 Technical Performance Criteria ...........................................................................................54
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GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page iv
Table 9-3 Financial Criteria .................................................................................................................. 54
Table 9-4. Environmental Criteria ......................................................................................................... 55
Table 9-5. MCA Category Weighing ..................................................................................................... 55
Table 9-6. Multi Criteria Decision Matrix .............................................................................................. 57
Table 9-7. Alternative Lifecycle Cost Estimates ................................................................................... 59
Table 11-1. Comparison of Sand Management Systems .................................................................... 73
Appendix Index
Appendix A Data Gathering Memorandum
Appendix B Numerical Modeling Report
Appendix C Multi-Criteria Decision Matrix & Alternative Cost Estimates
Appendix D Scientific Monitoring Plan (Scripps Institution of Oceanography)
[Q]Table 9-3 Financial Criteria ..................................................................................................................54
Table 9-4.Environmental Criteria.........................................................................................................55
Table 9-5.MCA Category Weighing.....................................................................................................55
Table 9-6.Multi Criteria Decision Matrix ..............................................................................................57
Table 9-7.Alternative Lifecycle Cost Estimates ...................................................................................59
Table 11-1.Comparison of Sand Management Systems ....................................................................73
Appendix Index
Appendix A Data Gathering Memorandum
Appendix B Numerical Modeling Report
Appendix C Multi-Criteria Decision Matrix &Alternative Cost Estimates
Appendix D Scientific Monitoring Plan (Scripps Institution of Oceanography)
GHD |Beach Sand Replenishment &Retention Device Project |June 2021 |Page ivJan. 4, 2022 Item 4 Page 14 of 229
GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 1
ES.1 Executive Summary
Since construction of the Oceanside Harbor complex 80 years ago, the City of Oceanside and U.S. Army
Corps of Engineers (USACE) have struggled to offset the erosional impacts to downdrift beaches. The
effect was described as an “erosional wave” that could be seen moving down the Oceanside Littoral Cell,
which spans from the harbor to La Jolla submarine canyon to the south (Jenkins and Inman 2003). During
this time, the City placed over 21M cubic yards (cy) of sand on their beaches from both the USACE’s harbor
dredging program (13.5M cy) and one-off, local or regional nourishment events (7.5M cy). This also includes
a limited volume of sand from the City and USACE’s Experimental Sand Bypass System that was
constructed in the 1980s in efforts to restore the natural transport pathway that was broken when the harbor
was constructed. All of these efforts have fallen short of providing the City with a sustained, dry sand beach
for recreational, ecological and coastal storm damage protection purposes.
The current condition of many City beaches is dismal for beach recreation, with many areas having little to
no dry beach during the majority of the tidal cycle. Wave events are impacting coastal infrastructure with
greater frequency and severity, resulting in the need for repairs and improvements to shoreline protection
systems. Projected sea level rise threatens to make these conditions worse.
Many factors contribute to the state of Oceanside beaches, but the most significant are the volume and
type of sand delivered to City beaches. The USACE’s harbor dredging program places silty sand from the
navigational channels on the beaches. This sand is easily mobilized by waves and forms a submerged
beach of little value for recreation and storm damage benefits. Coarse-gradation sand remains higher on
the upper beach profile and is required to form and sustain a dry beach area. Unfortunately, the primary
supply of coarse-gradation sand (littoral drift) is blocked by the Oceanside Harbor breakwater and
impounded in the upcoast fillet which has formed a 400-500 foot wide dry beach along Camp Pendleton’s
Del Mar Beach Resort.
The two Regional Beach Sand Projects (RBSP) carried out in 2001 and 2012 are the most recent efforts to
mitigate the coastal challenges in Oceanside. While these projects added coarse sand to a sediment
starved coastline, the benefits along Oceanside beaches were short-lived, with most of the sand moving
downcoast soon after placement. RBSP monitoring data indicate a large amount of the coarse-grained
sand placed in RBSP I and II at Oceanside and North Carlsbad remains in the fillet upcoast of the north
jetty at the Agua Hedionda Lagoon (i.e. Tamarack State Beach). The significant accretion at North Carlsbad
is a good example of the lasting benefits provided by the combination of a sand retention structure and a
supply of coarse-grained sand.
Four alternatives were developed to meet the City’s desire to protect beaches from long-term shoreline
erosion in an environmentally sensitive and financially feasible way. To this end, the Project approach is to
pilot the selected alternative in combination with a robust scientific monitoring program, as led by the
Scripps Institution of Oceanography. The pilot would be closely monitored for its performance in retention
of a beach as well as potential impacts to downdrift beaches and recreational resources. The South Strand
shoreline (i.e. between the pier and Wisconsin Avenue) was recommended as the Pilot Reach due to: the [Q]ES.1 Executive Summary
Since construction of the Oceanside Harbor complex 80 years ago,the City of Oceanside and U.S.Army
Corps of Engineers (USACE)have struggled to offset the erosional impacts to downdrift beaches.The
effect was described as an “erosional wave”that could be seen moving down the Oceanside Littoral Cell,
which spans from the harbor to La Jolla submarine canyon to the south (Jenkins and lnman 2003).During
this time,the City placed over 21 M cubic yards (cy)of sand on their beaches from both the USACE’s harbor
dredging program (13.5M cy)and one-off,local or regional nourishment events (7.5M cy).This also includes
a limited volume of sand from the City and USACE’s Experimental Sand Bypass System that was
constructed in the 1980s in efforts to restore the natural transport pathway that was broken when the harbor
was constructed.All of these efforts have fallen short of providing the City with a sustained,dry sand beach
for recreational,ecological and coastal storm damage protection purposes.
The current condition of many City beaches is dismal for beach recreation,with many areas having little to
no dry beach during the majority of the tidal cycle.Wave events are impacting coastal infrastructure with
greater frequency and severity,resulting in the need for repairs and improvements to shoreline protection
systems.Projected sea level rise threatens to make these conditions worse.
Many factors contribute to the state of Oceanside beaches,but the most significant are the volume and
type of sand delivered to City beaches.The USACE’s harbor dredging program places silty sand from the
navigational channels on the beaches.This sand is easily mobilized by waves and forms a submerged
beach of little value for recreation and storm damage benefits.Coarse-gradation sand remains higher on
the upper beach profile and is required to form and sustain a dry beach area.Unfortunately,the primary
supply of coarse-gradation sand (littoral drift)is blocked by the Oceanside Harbor breakwater and
impounded in the upcoast fillet which has formed a 400-500 foot wide dry beach along Camp Pendleton’s
Del Mar Beach Resort.
The two Regional Beach Sand Projects (RBSP)carried out in 2001 and 2012 are the most recent efforts to
mitigate the coastal challenges in Oceanside.While these projects added coarse sand to a sediment
starved coastline,the benefits along Oceanside beaches were short-lived,with most of the sand moving
downcoast soon after placement.RBSP monitoring data indicate a large amount of the coarse-grained
sand placed in RBSP l and II at Oceanside and North Carlsbad remains in the fillet upcoast of the north
jetty at the Agua Hedionda Lagoon (i.e.Tamarack State Beach).The significant accretion at North Carlsbad
is a good example of the lasting benefits provided by the combination of a sand retention structure and a
supply of coarse-grained sand.
Four alternatives were developed to meet the City’s desire to protect beaches from long-term shoreline
erosion in an environmentally sensitive and financially feasible way.To this end,the Project approach is to
pilot the selected alternative in combination with a robust scientific monitoring program,as led by the
Scripps Institution of Oceanography.The pilot would be closely monitored for its performance in retention
of a beach as well as potential impacts to downdrift beaches and recreational resources.The South Strand
shoreline (i.e.between the pier and Wisconsin Avenue)was recommended as the Pilot Reach due to:the
GHD |Beach Sand Replenishment &Retention Device Project |June 2021 |Page 1
Jan. 4, 2022 Item 4 Page 15 of 229
GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 2
erosion impacting this area, the popularity and accessibility of this reach and public ownership of the
landside right-of-way.
The four alternatives analyzed in this report are as follows:
• No Project assumes continuation of the status quo in which Harbor maintenance dredging is the
only program adding sand to the City beaches on a regular basis. The City would continue to
participate in regional nourishment efforts similar to RBSP I and II on an ad-hoc basis.
• Alternative 1: Beach Nourishment assumes a more frequent beach nourishment program is
carried out by the City to deliver 300,000 CY of sand once every five years, approximately doubling
the frequency of prior RBSP efforts.
• Alternative 2: Groins assumes construction of four, 600-foot long, rubble mound groins spaced
1,000 feet apart along the Pilot Reach. The proposed groins are shore-perpendicular and would
extend seaward from the existing rock revetment with a crest elevation of 10’ MLLW. A 300,000 cy
initial nourishment was included to pre-fill the groin field with subsequent nourishment volumes
reduced by about 50%.
• Alternative 3: San Luis Rey Groin Extension assumes construction of a 350-foot extension of
the existing groin to capture sand moving north toward the harbor. The sand trapped in this fillet
could possibly be used as a source for downcoast receiver beaches. This alternative includes a
beach nourishment component identical to Alternative 2.
• Alternative 4: Multi-purpose Artificial Reefs assumes construction of two 1,000-foot long, rubble
mound reefs spaced 1,200 feet apart along the Pilot Reach. Each reefs would have emergent and
submergent crest sections along their lengths to dissipate wave energy and potentially create a
surfable wave on each end of the reef. A 300,000 cy initial nourishment was included to pre-fill the
reef salients with subsequent nourishment volumes reduced by about 50%.
A multi-criteria analysis (MCA) was performed to compare alternatives based on a wide range of criteria
that reflects the diversity of opinions and input received from the outreach activities. Each alternative was
evaluated against 11 criteria, organized into three categories of Technical Performance, Financial, and
Environmental. The results of the MCA indicated the highest ranked alternative was Groins, followed by
Multi-purpose Reefs as illustrated in Figure ES-1. These top two alternatives were separated by 8% from
one another in total score, which was meaningful when considering the sensitivity of the scoring and
weighting system. Beach Nourishment ranked third, about 17% lower than the Groins and 9% lower than
Multi-purpose Reefs. The No Project alternative ranked last with very low scores in the Technical
Performance and Environmental categories. [Q]erosion impacting this area,the popularity and accessibility of this reach and public ownership of the
landside right-of-way.
The four alternatives analyzed in this report are as follows:
No Project assumes continuation of the status quo in which Harbor maintenance dredging is the
only program adding sand to the City beaches on a regular basis.The City would continue to
participate in regional nourishment efforts similar to RBSP |and II on an ad-hoc basis.
Alternative 1:Beach Nourishment assumes a more frequent beach nourishment program is
carried out by the City to deliver 300,000 CY of sand once every five years,approximately doubling
the frequency of prior RBSP efforts.
Alternative 2:Groins assumes construction of four,GOO-foot long,rubble mound groins spaced
1,000 feet apart along the Pilot Reach.The proposed groins are shore-perpendicular and would
extend seaward from the existing rock revetment with a crest elevation of 10'MLLW.A 300,000 cy
initial nourishment was included to pre-fill the groin field with subsequent nourishment volumes
reduced by about 50%.
Alternative 3:San Luis Rey Groin Extension assumes construction of a 350-foot extension of
the existing groin to capture sand moving north toward the harbor.The sand trapped in this fillet
could possibly be used as a source for downcoast receiver beaches.This alternative includes a
beach nourishment component identical to Alternative 2.
Alternative 4:Multi-purpose Artificial Reefs assumes construction of two 1,000-foot long,rubble
mound reefs spaced 1,200 feet apart along the Pilot Reach.Each reefs would have emergent and
submergent crest sections along their lengths to dissipate wave energy and potentially create a
surfable wave on each end of the reef.A 300,000 cy initial nourishment was included to pre-fill the
reef salients with subsequent nourishment volumes reduced by about 50%.
A multi-criteria analysis (MCA)was performed to compare alternatives based on a wide range of criteria
that reflects the diversity of opinions and input received from the outreach activities.Each alternative was
evaluated against 11 criteria,organized into three categories of Technical Performance,Financial,and
Environmental.The results of the MCA indicated the highest ranked alternative was Groins,followed by
Multi-purpose Reefs as illustrated in Figure ES—1.These top two alternatives were separated by 8%from
one another in total score,which was meaningful when considering the sensitivity of the scoring and
weighting system.Beach Nourishment ranked third,about 17%lower than the Groins and 9%lower than
Multi-purpose Reefs.The No Project alternative ranked last with very low scores in the Technical
Performance and Environmental categories.
GHD |Beach Sand Replenishment &Retention Device Project |June 2021 |Page 2
Jan. 4, 2022 Item 4 Page 16 of 229
GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 3
Figure ES-1: Summary of Multi-Criteria Analysis Scoring for Alternatives
The findings of this analysis are consistent with numerous prior studies that found groins to be a
preferred option for erosion protection in the City. Many of these studies discounted groins for social,
political or regulatory reasons. Studies with consistent findings are as follows:
• USACE (1980) – Design of Structures for Harbor Improvements and Beach Erosion Control.
Oceanside Harbor and Beach, CA.
• Noble and Associates (1983) – Report of proposed groin field in Oceanside
• USACE (1994) – Reconnaissance Report of Oceanside Shoreline
• Moffat and Nichol (2001) – SANDAG Regional Beach Sand Retention Strategy Report
• Gary Griggs et al. (2020) “Groins, Sand Retention and the Future of Southern California
Beaches”
• USACE (Ongoing) – Special Shoreline Study for San Diego.
The life-cycle costs for each of the alternatives is presented in Figure ES-2. Beach Nourishment has
a lower lifecycle cost than the Groins due to the initial cost of building the groin structures. The Groins
alternative has lower maintenance costs since less volume of nourishment is required over the
project duration. Multi-purpose Reefs was estimated to have the highest lifecycle cost due to the
significant volume of material required to build the artificial reef structures. Inclusion of a sand bypass
option into any of the proposed alternatives has the potential to significantly reduce beach
renourishment costs after the initial capital expenditure to construct the system.
8%
24%
30%
30%
24%
15%
16%
17%
8%
14%
10%
24%
34%
35%
24%
NO PROJECT
BEACH
NOURISHMENT
GROINS
MULTI-PURPOSE
REEFS
SLR GROIN
MODIFICATIONS
TECHNICAL PERFORMANCE (40%)FINANCIAL (20%)ENVIRONMENTAL (40%)
33%
64%
81%
73%
62% [Q]ITECHNICAL PERFORMANCE (40%)IFINANCIAL (20%)IENVIRONMENTAL (40%)
NO PROJECT 8%15% 10%33%
BEACHNOURISHMENT 24%16%24%64%
GROINS 30%17%34%81%
MULTl-PURPOSE 30%8%35%73%
REEFS
SLR G ROI N 24%14%24%62%MODIFICATIONS
Figure ES-1:Summary of Multi-Criteria Analysis Scoring for Alternatives
The findings of this analysis are consistent with numerous prior studies that found groins to be a
preferred option for erosion protection in the City.Many of these studies discounted groins for social,
political or regulatory reasons.Studies with consistent findings are as follows:
0 USACE (1980)—Design of Structures for Harbor Improvements and Beach Erosion Control.
Oceanside Harbor and Beach,CA.
0 Noble and Associates (1983)—Report of proposed groin field in Oceanside
o USACE (1994)—Reconnaissance Report of Oceanside Shoreline
o Moffat and Nichol (2001)—SANDAG Regional Beach Sand Retention Strategy Report
0 Gary Griggs et al.(2020)“Groins,Sand Retention and the Future of Southern California
Beaches”
o USACE (Ongoing)—Special Shoreline Study for San Diego.
The life-cycle costs for each of the alternatives is presented in Figure ES-2.Beach Nourishment has
a lower lifecycle cost than the Groins due to the initial cost of building the groin structures.The Groins
alternative has lower maintenance costs since less volume of nourishment is required over the
project duration.Multi-purpose Reefs was estimated to have the highest lifecycle cost due to the
significant volume of material required to build the artificial reef structures.Inclusion of a sand bypass
option into any of the proposed alternatives has the potential to significantly reduce beach
renourishment costs after the initial capital expenditure to construct the system.
GHD |Beach Sand Replenishment &Retention Device Project |June 2021 |Page 3
Jan. 4, 2022 Item 4 Page 17 of 229
GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 4
Figure ES-2: Estimated Lifecycle Costs for Alternatives
The beach area generated over the lifecycle of each alternative provides a useful metric for
comparing the benefit or value of each alternative. Modeling results of the pilot-scale sand retention
alternatives indicate they could potentially retain up to 18 acres of beach area, over three times larger
than the beach area generated within the initial placement area after RBSP II. While Beach
Nourishment has a significantly lower lifecycle cost, the area of beach generated is also significantly
lower. Groins require a larger capital expense, but offer the highest return on the investment with the
best chance of success in providing a stable dry beach along the pilot reach. A comparison of the
value in terms of cost per acre of beach area generated for each alternative is provided in Figure ES-
3.
$- $50,000,000 $100,000,000 $150,000,000
NO PROJECT
BEACH NOURISHMENT
GROINS
SLRR GROIN MODS
MULTI-PURPOSE REEFS[Q]MULTl-PURPOSE REEFS
SLRR GROIN MODS
GRoms —
BEACH NOURISHMENT
NO PROJECT
$-$50,000,000 $100,000,000 $150,000,000
Figure ES-2:Estimated Lifecycle Costs for Alternatives
The beach area generated over the lifecycle of each alternative provides a useful metric for
comparing the benefit or value of each alternative.Modeling results of the pilot-scale sand retention
alternatives indicate they could potentially retain up to 18 acres of beach area,over three times larger
than the beach area generated within the initial placement area after RBSP ll.While Beach
Nourishment has a significantly lower lifecycle cost,the area of beach generated is also significantly
lower.Groins require a larger capital expense,but offer the highest return on the investment with the
best chance of success in providing a stable dry beach along the pilot reach.A comparison of the
value in terms of cost per acre of beach area generated for each alternative is provided in Figure ES-
3.
GHD |Beach Sand Replenishment &Retention Device Project |June 2021 |Page 4
Jan. 4, 2022 Item 4 Page 18 of 229
GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 5
Figure ES-3: Value Comparison for each Alternative
The findings of this analysis give the Project team high confidence that Groins have the best chance
to protect against long-term shoreline erosion based on consideration of Technical Performance,
Financial and Environmental criteria. GHD recommends the Groin pilot-scale concept be advanced
for further analysis, additional public/agency outreach and preliminary design to prepare for the
environmental review and permitting process. Additional analysis of the Groin alternative would
involve sensitivity analyses on groin length and spacing, the pre-fill volumes and sand management
systems required to mitigate potential impacts.
Recognizing that any of the alternatives considered within this study require a long-term, high-quality
source of sand, a number of sediment management systems were evaluated in this study. The
systems evaluated include the following:
• Fixed Trestle Bypass: Construction of a fixed trestle (pier type structure) on Camp
Pendleton with a series of intake pumps extending into the surfzone/nearshore. The structure
would act to capture sand moving in the longshore direction and would transport large
quantities of sand (i.e. 100 to 300k cy per year) to City beaches via a network of shallow and
deep underground pipelines with multiple outlet locations.
• Semi-fixed Sand Bypass: Construction of a smaller bypass system (capable of moving 50
to 100k cy of sand per year) that could be moved relatively easily to accommodate changes
in the sand source location. Similar to the fixed system, this option would entail construction
of sand distribution pipelines transport sand within the City. This system could be
manipulated to source sand from the Camp Pendleton fillet, Harbor Beach or the San Luis
Rey River mouth.
$-
$1,000,000
$2,000,000
$3,000,000
$4,000,000
$5,000,000
$6,000,000
$7,000,000
$8,000,000
$9,000,000
Beach Nourishment Groins (Pilot)Reefs (Pilot)Cost/acre of beach areaAlternative
Value Comparisonl0]Value Comparison
$9,000,000
$8,000,000 —
$7,000,000 —
$6,000,000 —
$5,000,000 ——
$4,000,000 ——
$3,000,000 ———_Cost/acreofbeacharea$2,000,000 —___
$1,000,000 ————
s-_——_
Beach Nourishment Groins (Pilot)Reefs (Pilot)
Alternative
Figure ES-3:Value Comparison for each Alternative
The findings of this analysis give the Project team high confidence that Groins have the best chance
to protect against long-term shoreline erosion based on consideration of Technical Performance,
Financial and Environmental criteria.GHD recommends the Groin pilot-scale concept be advanced
for further analysis,additional public/agency outreach and preliminary design to prepare for the
environmental review and permitting process.Additional analysis of the Groin alternative would
involve sensitivity analyses on groin length and spacing,the pre-fill volumes and sand management
systems required to mitigate potential impacts.
Recognizing that any ofthe alternatives considered within this study require a long-term,high-quality
source of sand,a number of sediment management systems were evaluated in this study.The
systems evaluated include the following:
Fixed Trestle Bypass:Construction of a fixed trestle (pier type structure)on Camp
Pendleton with a series of intake pumps extending into the surfzone/nearshore.The structure
would act to capture sand moving in the longshore direction and would transport large
quantities of sand (i.e.100 to 300k cy per year)to City beaches via a network of shallow and
deep underground pipelines with multiple outlet locations.
Semi-fixed Sand Bypass:Construction of a smaller bypass system (capable of moving 50
to 100k cy of sand per year)that could be moved relatively easily to accommodate changes
in the sand source location.Similar to the fixed system,this option would entail construction
of sand distribution pipelines transport sand within the City.This system could be
manipulated to source sand from the Camp Pendleton fillet,Harbor Beach or the San Luis
Rey River mouth.
GHD |Beach Sand Replenishment &Retention Device Project |June 2021 |Page 5
Jan. 4, 2022 Item 4 Page 19 of 229
GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 6
• Piggyback on USACE Harbor Dredging Program: Construction of a series of underground
pipelines (as described in the above options) without purchasing mechanical dredge
equipment. This option assumes the City would “piggyback” on the USACE’s annual harbor
dredging program to bypass sand from the MCB Camp Pendleton fillet. Piggybacking on
other dredging operations is a common practice to and saves on contractor
mobilization/demobilization costs. Logistics surrounding how to access and dredge the fillet
would require further coordination with the dredge contractor and the MCB Camp Pendleton.
Without having secured a significant source of high-quality sand for the City, there is limited benefit
to further design and analysis of a sand bypass system. The ideal sand source for a sand bypass
system is the MCB Camp Pendleton fillet despite the significant political and jurisdictional obstacles
that exist. Should that sand source become available, the Semi-fixed Sand Bypass or USACE
Piggyback option should be evaluated more closely to determine the most cost-effective solution.
Recommended next steps are as follows:
1. Agency and Stakeholder Coordination & Engagement:
a. Overcoming the social, political and regulatory challenges surrounding the use of sand
retention structures is going to require continued coordination with key agencies and
stakeholders to address concerns surrounding downdrift impacts, recreational impacts
and precedent-setting type concerns. Key agencies to continue to engage include the
California Coastal Commission, Surfrider Foundation and other non-government
agencies that have expressed concern during this first phase.
b. Access to the sand source along the northern fillet is also a critical element in making
any sand bypassing option viable. Engagement with the MCB Camp Pendleton at the
appropriate level is also a key next step to securing a sustainable, high-quality source
of sand and progressing sand bypassing options.
2. Further Refine Groin Design:
a. Further engineering analysis and design of the Groin concept is needed to refine the
length, spacing, location, and structural details of these structures. The volume and
distribution of the initial nourishment will also depend on this additional analysis and
design effort.
b. Development adaptive management plan to address public, agency and stakeholder
concerns about potential impacts. The plan will identify triggers where action would be
taken to remedy an impact, if realized. The plan would be informed by the scientific
monitoring program.
3. Enhance Beach Data Monitoring Efforts: Beach width data is important to understand
changes and base management decisions on. Establishing a baseline of data will also be useful
should a sand retention pilot be constructed. The following monitoring actions are
recommended: [Q]o Piggyback on USACE Harbor Dredging Program:Construction of a series of underground
pipelines (as described in the above options)without purchasing mechanical dredge
equipment.This option assumes the City would “piggyback"on the USACE’s annual harbor
dredging program to bypass sand from the MCB Camp Pendleton fillet.Piggybacking on
other dredging operations is a common practice to and saves on contractor
mobilization/demobilization costs.Logistics surrounding how to access and dredge the fillet
would require further coordination with the dredge contractor and the MCB Camp Pendleton.
Without having secured a significant source of high-quality sand for the City,there is limited benefit
to further design and analysis of a sand bypass system.The ideal sand source for a sand bypass
system is the MCB Camp Pendleton fillet despite the significant political and jurisdictional obstacles
that exist.Should that sand source become available,the Semi-fixed Sand Bypass or USACE
Piggyback option should be evaluated more closely to determine the most cost-effective solution.
Recommended next steps are as follows:
1.Agency and Stakeholder Coordination &Engagement:
a.Overcoming the social,political and regulatory challenges surrounding the use of sand
retention structures is going to require continued coordination with key agencies and
stakeholders to address concerns surrounding downdrift impacts,recreational impacts
and precedent-setting type concerns.Key agencies to continue to engage include the
California Coastal Commission,Surfrider Foundation and other non-government
agencies that have expressed concern during this first phase.
Access to the sand source along the northern fillet is also a critical element in making
any sand bypassing option viable.Engagement with the MCB Camp Pendleton at the
appropriate level is also a key next step to securing a sustainable,high-quality source
of sand and progressing sand bypassing options.
2.Further Refine Groin Design:
a.Further engineering analysis and design of the Groin concept is needed to refine the
length,spacing,location,and structural details of these structures.The volume and
distribution of the initial nourishment will also depend on this additional analysis and
design effort.
Development adaptive management plan to address public,agency and stakeholder
concerns about potential impacts.The plan will identify triggers where action would be
taken to remedy an impact,if realized.The plan would be informed by the scientific
monitoring program.
3.Enhance Beach Data Monitoring Efforts:Beach width data is important to understand
changes and base management decisions on.Establishing a baseline of data will also be useful
should a sand retention pilot be constructed.The following monitoring actions are
recommended:
GHD |Beach Sand Replenishment &Retention Device Project |June 2021 |Page 6
Jan. 4, 2022 Item 4 Page 20 of 229
GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 7
a. Continue to support tracking of subaerial beach widths (dry beach) with the citizen
science program conducted by Save Oceanside Sand (SOS) and others in
coordination with the Scripps Institution of Oceanography (SIO).
b. Annual to bi-annual, high resolution beach and nearshore SIO “Jumbo Surveys” are
recommended to track the spatial and temporal changes in sand in the City. These
surveys supplement the subaerial surveys and provide a greater level of detail than
the existing regional transect monitoring program.
4. Develop Project Financing Strategy: Any of the alternatives considered will require a
significant amount of capital and operational expenditure. Financing strategies should be
considered in concert with seeking state and federal grant funds for the Project.
5. Stay Actively Engaged in Local and Regional Sediment Management Activities: The City
should remain actively engaged in ongoing management activities and seek new sources of
sand, as they become available. This recommendation works in concert with the sediment
retention project as local sediment management activities alone will lack the magnitude or
quality to sustain beaches in the city.
a. Continue to engage with the USACE on annual harbor dredging program activities.
The timing, placement methods and locations should be discussed to see if they can
be modified to increase local benefits.
b. Continue to seek opportunistic sources of sand (i.e. San Luis Rey River, Buena Vista
Lagoon Restoration, etc.) for beach nourishment. Maintain City’s permits for the
Opportunistic Beach Fill Program to streamline approval of these sand sources as they
become available.
c. Continue to participate in future regional beach sand projects with consideration for
different placement locations, quantities or timing within the City to increase local
benefits.
Continue to support tracking of subaerial beach widths (dry beach)with the citizen
science program conducted by Save Oceanside Sand (SOS)and others in
coordination with the Scripps Institution of Oceanography (SIO).
Annual to bi-annual,high resolution beach and nearshore SIO “Jumbo Surveys”are
recommended to track the spatial and temporal changes in sand in the City.These
surveys supplement the subaerial surveys and provide a greater level of detail than
the existing regional transect monitoring program.
Develop Project Financing Strategy:Any of the alternatives considered will require a
significant amount of capital and operational expenditure.Financing strategies should be
considered in concert with seeking state and federal grant funds for the Project.
Stay Actively Engaged in Local and Regional Sediment Management Activities:The City
should remain actively engaged in ongoing management activities and seek new sources of
sand,as they become available.This recommendation works in concert with the sediment
retention project as local sediment management activities alone will lack the magnitude or
quality to sustain beaches in the city.
a.Continue to engage with the USACE on annual harbor dredging program activities.
The timing,placement methods and locations should be discussed to see if they can
be modified to increase local benefits.
Continue to seek opportunistic sources of sand (i.e.San Luis Rey River,Buena Vista
Lagoon Restoration,etc.)for beach nourishment.Maintain City’s permits for the
Opportunistic Beach Fill Program to streamline approval ofthese sand sources as they
become available.
Continue to participate in future regional beach sand projects with consideration for
different placement locations,quantities or timing within the City to increase local
benefits.
GHD |Beach Sand Replenishment &Retention Device Project |June 2021 |Page 7
Jan. 4, 2022 Item 4 Page 21 of 229
GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 8
1. Introduction
Despite existing sediment management and planning efforts, City of Oceanside (City) beaches are
in severely eroded condition leaving many areas with limited or no dry beach. The City understands
the importance of sandy beaches for protection of coastal infrastructure, recreation and the local
economy. The City seeks to identify feasibility solutions to protect and restore their shoreline by either
utilizing re-nourishment projects or construction of sand retention devices, or a combination of both.
Sand retention structures (e.g. groins, breakwaters) act to retain/reduce the loss of sand on an
eroding shoreline by altering the effects approaching waves. The City acknowledges the potential
regulatory and funding challenges with the solutions being considered and wishes to identify
strategies that are environmentally sensitive, financially feasible and have a reasonable chance of
being approved through the regulatory permitting process.
The City retained GHD Inc. (GHD) to undertake a preliminary engineering evaluation of feasible
options for the Beach Sand Replenishment and Retention Device Project (Project). The scope of this
study included the following major tasks:
• Coastal Data & Project Review: Gather and assimilate existing coastal data and data on similar,
global project examples in order to understand the City problem and bring forward viable
solutions.
• Concept Design: Develop beach nourishment and sand retention concepts to be evaluated
within the study. Concepts to be evaluated through a multi-criteria decision matrix.
• Numerical Modeling of Concepts: Develop and validate a coastal numerical model to evaluate
the performance of beach nourishment and sand retention concepts.
• Estimate Future Costs: Develop soft (i.e. design, permitting, outreach) and hard (i.e.
construction and adaptation) cost estimates for the concepts being considered.
• Scientific Baseline & Monitoring Plan: Develop a scientific baseline for the Study Area and a
robust monitoring plan that can be implemented to test any of the nourishment or sand retention
options once constructed. Scripps Institution of Oceanography (SIO), working under a
subcontract with GHD, led this work.
• Resource Agency, Stakeholder and Coastal City Coordination Meetings: Early coordination
with each of these groups to receive feedback of options being considered.
The study area for the Project extends from Camp Pendleton to the north and Agua Hedionda Lagoon
to the south (Figure 1-1). The Project Area, or area of focus, for the study includes the City’s southern
shoreline from about the Oceanside Pier to Buena Vista Lagoon (Figure 1-2). The Project Area is
severely eroded and has little sustained dry beach for the last 10 years compared to beaches north
of the pier. [Q]1.Introduction
Despite existing sediment management and planning efforts,City of Oceanside (City)beaches are
in severely eroded condition leaving many areas with limited or no dry beach.The City understands
the importance of sandy beaches for protection of coastal infrastructure,recreation and the local
economy.The City seeks to identify feasibility solutions to protect and restore their shoreline by either
utilizing re-nourishment projects or construction of sand retention devices,or a combination of both.
Sand retention structures (e.g.groins,breakwaters)act to retain/reduce the loss of sand on an
eroding shoreline by altering the effects approaching waves.The City acknowledges the potential
regulatory and funding challenges with the solutions being considered and wishes to identify
strategies that are environmentally sensitive,financially feasible and have a reasonable chance of
being approved through the regulatory permitting process.
The City retained GHD Inc.(GHD)to undertake a preliminary engineering evaluation of feasible
options for the Beach Sand Replenishment and Retention Device Project (Project).The scope of this
study included the following major tasks:
0 Coastal Data &Project Review:Gather and assimilate existing coastal data and data on similar,
global project examples in order to understand the City problem and bring fonrvard viable
solutions.
0 Concept Design:Develop beach nourishment and sand retention concepts to be evaluated
within the study.Concepts to be evaluated through a multi-criteria decision matrix.
0 Numerical Modeling of Concepts:Develop and validate a coastal numerical model to evaluate
the performance of beach nourishment and sand retention concepts.
0 Estimate Future Costs:Develop soft (i.e.design,permitting,outreach)and hard (i.e.
construction and adaptation)cost estimates for the concepts being considered.
0 Scientific Baseline &Monitoring Plan:Develop a scientific baseline for the Study Area and a
robust monitoring plan that can be implemented to test any of the nourishment or sand retention
options once constructed.Scripps Institution of Oceanography (SIO),working under a
subcontract with GHD,led this work.
0 Resource Agency,Stakeholder and Coastal City Coordination Meetings:Early coordination
with each of these groups to receive feedback of options being considered.
The study area for the Project extends from Camp Pendleton to the north and Agua Hedionda Lagoon
to the south (Figure 1-1).The Project Area,or area of focus,for the study includes the City’s southern
shoreline from about the Oceanside Pier to Buena Vista Lagoon (Figure 1-2).The Project Area is
severely eroded and has little sustained dry beach for the last 10 years compared to beaches north
of the pier.
GHD |Beach Sand Replenishment &Retention Device Project |June 2021 |Page 8
Jan. 4, 2022 Item 4 Page 22 of 229
GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 9
Figure 1-1. Project Location [Q]a .Ior.$0 LmAita +3O‘-Creek -
:70
mmLagoon
Agua HediondaLagoon
San Diego '_
Tijuana a '
.'5,
...fixagfL
”H_...
Figure 1-1.Project Location
GHD |Beach Sand Replenishment &Retention Device Project |June 2021 |Page 9
Jan. 4, 2022 Item 4 Page 23 of 229
GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 10
Figure 1-2. Project Area [Q]“WWII-InsaneMun-m:NONI!mmuwnnmmmm
Figure 1-2.Project Area
GHD |Beach Sand Replenishment &Retention Device Project |June 2021 |Page 10
Jan. 4, 2022 Item 4 Page 24 of 229
GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 11
2. Coastal Setting
Oceanside is the northernmost city of the Oceanside Littoral Cell. A littoral cell is a segment of
coastline with unique sediment sources, pathways and sinks that all impact or benefit the shorelines
within it. The cell is bounded to the north by the Dana Point Harbor and to the south by La Jolla
submarine canyon. Primary sediment sources to the cell include rivers, bluff erosion, gully/terrace
erosion and beach nourishment. Natural sediment delivery to the coastline has generally declined
over time within the cell as a result of various forms of development impeding their flow.
The majority of the City’s shoreline is protected by seawalls and rock revetments. The City’s bluffs
are setback behind these protection devices in many locations. Other parts of the shoreline are
modified by shore-perpendicular coastal structures, including a rock groin at the San Luis Rey River,
the Oceanside Harbor breakwaters and the Oceanside Pier.
The wave climate within the City is characterized by seasonal long-period swells generated by distant
storms in the North Pacific and Southern Oceans. Southern swell arrives at Oceanside from the
southwest through the spring and summer months and transports sand to the north (Figure 2-1).
Larger North Pacific swell approaching from the northwest and west during the fall and winter months
transports sand to the south (Figure 2-2). Locally generated short-period wind waves can occur any
time during the year and typically come from the west.
Waves are the dominant driver of sediment transport along Oceanside beaches. The net longshore sediment transport patterns for Oceanside are accepted to be southern, although seasonal variations are
common and depend on the swell direction. There are numerous estimates of the longshore sediment transport for Oceanside and within the Oceanside Littoral Cell, as shown in [Q]Coastal Setting
Oceanside is the northernmost city of the Oceanside Littoral Cell.A littoral cell is a segment of
coastline with unique sediment sources,pathways and sinks that all impact or benefit the shorelines
within it.The cell is bounded to the north by the Dana Point Harbor and to the south by La Jolla
submarine canyon.Primary sediment sources to the cell include rivers,bluff erosion,gully/terrace
erosion and beach nourishment.Natural sediment delivery to the coastline has generally declined
over time within the cell as a result of various forms of development impeding their flow.
The majority of the City’s shoreline is protected by seawalls and rock revetments.The City’s bluffs
are setback behind these protection devices in many locations.Other parts of the shoreline are
modified by shore-perpendicular coastal structures,including a rock groin at the San Luis Rey River,
the Oceanside Harbor breakwaters and the Oceanside Pier.
The wave climate within the City is characterized by seasonal long-period swells generated by distant
storms in the North Pacific and Southern Oceans.Southern swell arrives at Oceanside from the
southwest through the spring and summer months and transports sand to the north (Figure 2—1).
Larger North Pacific swell approaching from the northwest and west during the fall and winter months
transports sand to the south (Figure 2—2).Locally generated short-period wind waves can occur any
time during the year and typically come from the west.
Waves are the dominant driver of sediment transport along Oceanside beaches.The net longshore
sediment transport patterns for Oceanside are accepted to be southern,although seasonal variations are
common and depend on the swell direction.There are numerous estimates of the longshore sediment
transport for Oceanside and within the Oceanside Littoral Cell,as shown in
GHD |Beach Sand Replenishment &Retention Device Project |June 2021 |Page 11
Jan. 4, 2022 Item 4 Page 25 of 229
GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 12
Table 2-1. These estimates are based on historic studies and have not been updated or field verified
recently. However, amongst these studies there is general agreement that Oceanside experiences
a net sediment transport to the south of 100,000 to 200,000 cubic yards (cy) per year.
Sediment also moves in the cross-shore direction within the Oceanside Littoral Cell and is estimated
to range from 26,000 to 113,000 cy/year (USACE, 1991). Cross-shore transport predominantly
occurs during high energy wave events and are most likely be concentrated at creek mouths and
around structures (USACE, 1994).
Table 2-1. Longshore Sediment Transport Estimates
Location
Estimated
Gross
Northern
Transport
Rate (cy/yr)
Estimated
Gross
Southern
Transport
Rate (cy/yr)
Estimated Net
Longshore
Transport Rate
(cy/yr)
Direction Source
Oceanside Littoral Cell
545,000 760,000 215,000 South Marine Advisors (1961)
NA NA 250,000 South Inman (1976)
550,000 740,000 194,000 South
Hales (1979); Inman &
Jenkins (1985); Dolan
et al. (1987)
Oceanside Harbor
Southside 934,000 106,000 South USACE, (1991);
Tekmarine, Inc., (1978)
Oceanside NA NA 146,000 South Patsch & Griggs, 2006
Oceanside 553,000 807,000 254,000 South Inman & Jenkins
(1983)
Oceanside 541,000 643,000 102,000 South Hales (1978)
[0]Table 2-1.These estimates are based on historic studies and have not been updated or field verified
recently.However,amongst these studies there is general agreement that Oceanside experiences
a net sediment transport to the south of 100,000 to 200,000 cubic yards (cy)per year.
Sediment also moves in the cross-shore direction within the Oceanside Littoral Cell and is estimated
to range from 26,000 to 113,000 cy/year (USACE,1991).Cross-shore transport predominantly
occurs during high energy wave events and are most likely be concentrated at creek mouths and
around structures (USACE,1994).
Table 2-1.Longshore Sediment Transport Estimates
Estimated Estimated Estimated Net
Gross Gross Lon shore
Location Northern Southern 9 DirectionTransportRateTransport Transport (c /r)
Rate (cy/yr)Rate (cy/yr)y y
545,000 760,000 215,000 South Marine Advisors (1961)
NA NA 250,000 South Inman (1976)
Oceanside Littoral Cell Hales (1979);Inman &
550,000 740,000 194,000 South Jenkins (1985);Dolan
et al.(1987)
Oceanside Harbor USACE,(1991);Southside 934’000 106'000 S°Uth Tekmarine,Inc.,(1978)
Oceanside NA NA 146,000 South Patsch &Griggs,2006
Oceanside 553,000 807,000 254,000 South '“maa‘g‘éginkms
Oceanside 541 ,000 643,000 102,000 South Hales (1978)
GHD |Beach Sand Replenishment &Retention Device Project |June 2021 |Page 12
Jan. 4, 2022 Item 4 Page 26 of 229
GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 13
Figure 2-1. Summer Wave Height and Approach Direction (CDIP Station 045
2000-2020)
Figure 2-2. Winter Wave Height and Approach Direction (CDIP Station 045 2000-
2020)
LOCATION
If(EMuECVflO-WEES)Figure 2-1.Summer Wave Height and Approach Direction (CDIP Station 045
2000-2020)
LOCATION
gE;EEiE3
lb:HI(ii):17.75
Figure 2-2.Winter Wave Height and Approach Direction (CDIP Station 045 2000-
2020)
GHD |Beach Sand Replenishment &Retention Device Project |June 2021 |Page 13
Jan. 4, 2022 Item 4 Page 27 of 229
GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 14
3. Historical Perspective
3.1 Chronology of Coastal Development & Human Interventions
The U.S. Marine Corps constructed the Del Mar Boat Basin in 1942 to support amphibious training
efforts for WWII (USACE, 2016). The original construction consisted of two shore-perpendicular
jetties and dredging of a rectangular basin between the mouths of the Santa Margarita and San Luis
Rey Rivers. The harbor jetties were extended in 1950. In 1963 the Boat Basin was expanded to
include Oceanside Small Craft Harbor. Sand from the construction of these harbor improvements
were placed on City beaches.
Despite the addition of sand from harbor construction, increased erosion was observed on City
beaches after the harbor improvements were completed. As early as 1956, the government stipulated
in a House Document (399/84/2) that Camp Pendleton Harbor was primarily responsible for the
Oceanside beach erosion problem (USACE, 2016). Since the early 1940s, additional sand fill has
been placed on City beaches. Sand replenishment efforts have been insufficient and have not had a
long term, lasting impact as the beaches continue to recede (USACE, 2016).
In response to the heightened sediment deficiency on City beaches and desire for a long-term fix, a
fixed sand bypassing pilot project was constructed in the 1980’s within Oceanside Harbor (Figure
3-1). This system operated from 1989 to 1992 and was designed to pump 150,000 CY of sand from
northern harbor fillet in the winter months and 200,000 CY from the channel entrance in the summer
months (USACE, 1995; USACE, 1996).
The project had a multitude of issues revolving around maintenance of the pumps, sand recharge
within sand collection areas and inadequate federal funding. With an estimated total cost of $5 million
and an actual cost of $15 million, only the first two phases of the project were completed (Boswood
& Murray, 2001). This system only bypassed around 124,000 CY of sand from 1989 to 1992 before
becoming ultimately decommissioned.
[6]Historical Perspective
3.1 Chronology of Coastal Development &Human Interventions
The US.Marine Corps constructed the Del Mar Boat Basin in 1942 to support amphibious training
efforts for WWII (USACE,2016).The original construction consisted of two shore-perpendicular
jetties and dredging of a rectangular basin between the mouths of the Santa Margarita and San Luis
Rey Rivers.The harbor jetties were extended in 1950.In 1963 the Boat Basin was expanded to
include Oceanside Small Craft Harbor.Sand from the construction of these harbor improvements
were placed on City beaches.
Despite the addition of sand from harbor construction,increased erosion was observed on City
beaches afterthe harbor improvements were completed.As early as 1956,the government stipulated
in a House Document (399/84/2)that Camp Pendleton Harbor was primarily responsible for the
Oceanside beach erosion problem (USACE,2016).Since the early 19405,additional sand fill has
been placed on City beaches.Sand replenishment efforts have been insufficient and have not had a
long term,lasting impact as the beaches continue to recede (USACE,2016).
In response to the heightened sediment deficiency on City beaches and desire for a long-term fix,a
fixed sand bypassing pilot project was constructed in the 1980's within Oceanside Harbor (Figure
3-1).This system operated from 1989 to 1992 and was designed to pump 150,000 CY of sand from
northern harbor fillet in the winter months and 200,000 CY from the channel entrance in the summer
months (USACE,1995;USACE,1996).
The project had a multitude of issues revolving around maintenance of the pumps,sand recharge
within sand collection areas and inadequate federal funding.With an estimated total cost of $5 million
and an actual cost of $15 million,only the first two phases of the project were completed (Boswood
&Murray,2001 ).This system only bypassed around 124,000 CY of sand from 1989 to 1992 before
becoming ultimately decommissioned.
GHD |Beach Sand Replenishment &Retention Device Project |June 2021 |Page 14
Jan. 4, 2022 Item 4 Page 28 of 229
GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 15
Figure 3-1. Fixed Sediment Bypass Pilot
3.2 Oceanside Harbor Maintenance Dredging Program
Since 1942, sand has been dredged annually from the Oceanside Harbor federal navigational
channels and placed in the City within four designated sites (Figure 3-2). Decisions around how much
sediment is placed at each of the four sites is made by the USACE, the dredging contractor and City
staff. The decision is contingent on a variety of factors including beach conditions and need, volume
to be dredged, environmental factors (i.e. grunion, least terns) and safety. In recent years, the
dredging contractor has cited the need to place enough sand in front of the North Coast Village and
Oceanside Pier Lifeguard Headquarters revetments in order to have adequate beach to laydown the
dredge pipeline.
Dredging occurs every year in the spring over a period of about two to four weeks. However, a
number of emergency dredging events have occurred in the fall as a result of the harbor shoaling
after significant south swell events. The harbor dredging program is cost-shared by the USACE and
Navy. However, the City will commonly pay additional money into the program to receive additional
sand.
In total, approximately 18 million CY of sand has been bypassed from the harbor since the
construction (Table 3-1 and Figure 3-3). The total volume of dredged sediment from the harbor has
decreased since the dredging program began. From 1945 to 1981, the average volume of sediment
dredged was approximately 412,000 CY. From 1994 to 2020, the average volume of dredged
sediment was 253,000 CY. Dredged sediment from the harbor consists mainly of fine sands, with a
mean median grain size (D50) between 0.1 mm and 0.2 mm (data average between 2012 and 2020),
which is unlikely to remain on the upper beach profile to form a dry beach as discussed in Section
4.2. [Q]\
mmm
mmm
mamas-nu
Figure 3-1.Fixed Sediment Bypass Pilot
3.2 Oceanside Harbor Maintenance Dredging Program
Since 1942,sand has been dredged annually from the Oceanside Harbor federal navigational
channels and placed in the City within four designated sites (Figure 3-2).Decisions around how much
sediment is placed at each of the four sites is made by the USACE,the dredging contractor and City
staff.The decision is contingent on a variety of factors including beach conditions and need,volume
to be dredged,environmental factors (i.e.grunion,least terns)and safety.In recent years,the
dredging contractor has cited the need to place enough sand in front of the North Coast Village and
Oceanside Pier Lifeguard Headquarters revetments in order to have adequate beach to laydown the
dredge pipeline.
Dredging occurs every year in the spring over a period of about two to four weeks.However,a
number of emergency dredging events have occurred in the fall as a result of the harbor shoaling
after significant south swell events.The harbor dredging program is cost-shared by the USACE and
Navy.However,the City will commonly pay additional money into the program to receive additional
sand.
In total,approximately 18 million CY of sand has been bypassed from the harbor since the
construction (Table 3-1 and Figure 3-3).The total volume of dredged sediment from the harbor has
decreased since the dredging program began.From 1945 to 1981,the average volume of sediment
dredged was approximately 412,000 CY.From 1994 to 2020,the average volume of dredged
sediment was 253,000 CY.Dredged sediment from the harbor consists mainly of fine sands,with a
mean median grain size (D50)between 0.1 mm and 0.2 mm (data average between 2012 and 2020),
which is unlikely to remain on the upper beach profile to form a dry beach as discussed in Section
4.2.
GHD |Beach Sand Replenishment &Retention Device Project |June 2021 |Page 15
If..Wl ‘.‘.‘:..‘:.‘..~..',...'.!a'-''l.‘!:h....10...5v-..
ilillf
Jan. 4, 2022 Item 4 Page 29 of 229
GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 16
Over the last decade or more, sediment has been recovered using a cutterhead suction dredge,
transported south in a 24” HDPE slurry pipe, and discharged onto intertidal portions of the beach.
Dozers then scrape material up from the intertidal to the foreshore or dry beach downdrift of the
discharge pipe. Training dikes are not currently used to capture sand from the slurry on the beach,
as is typical for beach nourishment projects.
Table 3-1. Chronology of Coastal Development and Interventions in Oceanside
Year Activity Type Description Reference
1942-1944 Harbor Construction & Beach Nourishment Del Mar Boat Basin Construction. 1.5 mcy of sand placed on City beaches. Moffatt and Nichol, 1982
1952 Groin Construction Two, 50-foot groins constructed at Wisconsin Avenue and 1,000 feet south (vicinity of Marron
Street).
USACE
1958
Harbor Construction &
Beach Nourishment
Del Mar Boat basin and Harbor Improvements.
About ~800,000 cy of sand placed on City beaches.
Moffatt and Nichol, 1982
1962-1963 Harbor Construction & Beach Nourishment Recreational and Small Craft Harbor construction. 3.4 mcy of sand placed on City
beaches.
USACE, 1994
1966 Beach Nourishment 684,000 CY placed on City beaches. USACE, 1994
1968 Groin Construction San Luis Rey River Groin Constructed USACE, 1994
1981 Beach Nourishment 863,000 placed in Oceanside USACE, 1994
1982 Beach Nourishment 922,000 CY placed in Oceanside USACE, 1994
1982 Beach Nourishment 1.3 mcy of sand placed on City beaches from
San Luis Rey River dredging.
Flick, R.E.,
1993
1985 Sand Bypassing System
Construction
Sand Bypass Discharge Line constructed within
Oceanside Harbor.
O’Hara &
Graves, 1991
1989-1992
Sand Bypassing Sand bypass operation begins 1989. Bypassed
a total of 124,300 CY of sand between 1989 to 1992
Boswood & Murray, 2001
1992 Sand Bypass System Decommissioned
2001 Beach Nourishment 421,000 cy placed in Oceanside as part of RBSP I Coastal Frontiers Corp,
2020
2012
Beach Nourishment 293,000 cy placed in Oceanside as part of RBSP
II
Coastal
Frontiers Corp, 2020
[9]Over the last decade or more,sediment has been recovered using a cutterhead suction dredge,
transported south in a 24”HDPE slurry pipe,and discharged onto intertidal portions of the beach.
Dozers then scrape material up from the intertidal to the foreshore or dry beach downdrift of the
discharge pipe.Training dikes are not currently used to capture sand from the slurry on the beach,
as is typical for beach nourishment projects.
Table 3-1.Chronology of Coastal Development and Interventions in Oceanside
1 942-1 944
1 952
1 958
1962-1963
1 966
1 968
1981
1982
1 982
1 985
1 989-1 992
1 992
2001
2012
Harbor Construction &
Beach Nourishment
Groin Construction
Harbor Construction &
Beach Nourishment
Harbor Construction &
Beach Nourishment
Beach Nourishment
Groin Construction
Beach Nourishment
Beach Nourishment
Beach Nourishment
Sand Bypassing System
Construction
Sand Bypassing
Sand Bypass System
Decommissioned
Beach Nourishment
Beach Nourishment
Del Mar Boat Basin Construction.1.5 mcy of
sand placed on City beaches.
Two,50-foot groins constructed at Wisconsin
Avenue and 1,000 feet south (vicinity of MarronStreet).
Del Mar Boat basin and Harbor Improvements.
About ~800,000 cy of sand placed on City
beaches.
Recreational and Small Craft Harbor
construction.3.4 mcy of sand placed on City
beaches.
684,000 CY placed on City beaches.
San Luis Rey River Groin Constructed
863,000 placed in Oceanside
922,000 CY placed in Oceanside
1.3 mcy of sand placed on City beaches from
San Luis Rey River dredging.
Sand Bypass Discharge Line constructed within
Oceanside Harbor.
Sand bypass operation begins 1989.Bypassedatotalof124,300 CY of sand between 1989 to
1992
421,000 cy placed in Oceanside as part of RBSP
|
293,000 cy placed in Oceanside as part of RBSP
||
Moffatt and
Nichol,1982
USACE
Moffatt and
Nichol,1982
USACE,1994
USACE,1994
USACE,1994
USACE,1994
USACE,1994
Flick,RE,
1993
O’Hara &
Graves,1991
Boswood &
Murray,2001
Coastal
Frontiers Corp,
2020
Coastal
Frontiers Corp,
2020
GHD |Beach Sand Replenishment &Retention Device Project |June 2021 |Page 16
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GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 17
Figure 3-2. USACE Harbor Dredging Sand Placement Locations (USACE 2020)
[Q]M12”0 W “W@gcsmsmaGENERALSITEPLAN69
Figure 3-2.USACE Harbor Dredging Sand Placement Locations (USACE 2020)
GHD |Beach Sand Replenishment &Retention Device Project |June 2021 |Page 17
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GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 18
Figure 3-3. Oceanside Harbor Annual Dredge Volumes from 1942-2020
3.3 Regional Beach Sand Projects
The City has participated in two Regional Beach Sand Projects (RBSP) carried out by the San Diego
Association of Governments (SANDAG). In 2001, the RBSP I placed a total of 2 million cy of sand
onto 12 beaches within San Diego County. The City received 421,000 cy of sand from this project in
the vicinity of Tyson Street. North Carlsbad received 225,000 cy and South Carlsbad received
158,000 cy. Most of the material placed at Oceanside and Carlsbad had a coarser gradation than
native sand with a median grain size of 0.62mm (Coastal Frontiers, 2020; Noble Consultants, 2001).
In 2012, the RBSP II placed a total of 1.5 million cy of sand onto eight beaches in San Diego County.
Oceanside received 292,000 cy of sand between Buccaneer Beach and Hayes Street. North
Carlsbad received 218,000 cubic yards distributed from the Buena Vista Lagoon mouth to Carlsbad
Village Drive (SANDAG, 2020). The median grain size of the sand placed in Oceanside was a coarse
sand (0.54mm) (Coastal Frontiers, 2020). While these beach fills provided a coarse gradation sand
source conducive to dry beach formation, this material moved downcoast rather quickly with only
temporary benefits for Oceanside. More analysis and discussion of the performance of these projects
are provided in Section 3.4 and 4.3.
3.4 Shoreline Changes
Based on review of historical photos from the late 1800s and early 1900s, beaches in the City were
observed to be wide and basically stable (USACE, 2016). Beach widths were controlled by the
amount of sediment the rivers contributed to the littoral zone and by the longshore transport rate.
0
100,000
200,000
300,000
400,000
500,000
600,000
700,000
800,000
1960 1970 1980 1990 2000 2010 2020Volume (CY)Dredge Volumes[0]800,000
700,000
600,000
0
500,000 r (Y
400,000
Volume(CY)300,000 —
200 000’b
100,000
1960 1970 1980 1990 2000 2010 2020
—e—Dredge Volumes
Figure 3-3.Oceanside Harbor Annual Dredge Volumes from 1942-2020
3.3 Regional Beach Sand Projects
The City has participated in two Regional Beach Sand Projects (RBSP)carried out by the San Diego
Association of Governments (SANDAG).In 2001,the RBSP I placed a total of 2 million cy of sand
onto 12 beaches within San Diego County.The City received 421,000 cy of sand from this project in
the vicinity of Tyson Street.North Carlsbad received 225,000 cy and South Carlsbad received
158,000 cy.Most of the material placed at Oceanside and Carlsbad had a coarser gradation than
native sand with a median grain size of 0.62mm (Coastal Frontiers,2020;Noble Consultants,2001).
In 2012,the RBSP ll placed a total of 1.5 million cy of sand onto eight beaches in San Diego County.
Oceanside received 292,000 cy of sand between Buccaneer Beach and Hayes Street.North
Carlsbad received 218,000 cubic yards distributed from the Buena Vista Lagoon mouth to Carlsbad
Village Drive (SANDAG,2020).The median grain size of the sand placed in Oceanside was a coarse
sand (0.54mm)(Coastal Frontiers,2020).While these beach fills provided a coarse gradation sand
source conducive to dry beach formation,this material moved downcoast rather quickly with only
temporary benefits for Oceanside.More analysis and discussion of the performance of these projects
are provided in Section 3.4 and 4.3.
3.4 Shoreline Changes
Based on review of historical photos from the late 1800s and early 19003,beaches in the City were
observed to be wide and basically stable (USACE,2016).Beach widths were controlled by the
amount of sediment the rivers contributed to the littoral zone and by the longshore transport rate.
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Seasonal fluctuations were generally small except near the mouths of San Luis Rey and Santa
Margarita Rivers. The San Luis Rey and Santa Margarita Rivers were dammed after the floods of
1916 and 1936/1938, respectively. These dams significantly reduced the amount of sand entering
the Oceanside littoral zone (USACE, 2016). The shoreline in the City has changed dramatically over
the past century (Figure 3-4). Comparison of the 1934 and 1998 shoreline show the severe erosion
downcoast of the harbor during the 64-year period. Conversely, accretion is observed on the updrift
side of the harbor at Camp Pendleton.
Figure 3-4. Historical Shoreline Positions in the City (USACE 2015)
Recent shoreline change was evaluated using beach profile data collected by Coastal Frontiers
Corporation (CFC) from 1995 through 2018 and made available to the public on SANDAG’s website.
This data consists of surveyed beach profiles collected in fall and spring seasons on an annual basis.
Ten profiles within the study reach have been surveyed since 1995 providing useful data for
evaluating shoreline change over the last several decades. Two South Oceanside beach profiles
(OS-947 and OS-915) were established for the RBSP projects and therefore only provide data before
and after these nourishment events. The location of these profiles are shown in Figure 3-6. The mean
sea level shoreline position data illustrate clear trends of shoreline change that have been organized
into three distinct reaches, discussed in this section.
3.4.1 North Oceanside
Shoreline change in this reach is characterized by beach profiles OS-1070 (Harbor Beach) through
OS-1000 (South Strand, Tyson Street), all of which show a clear trend of shoreline erosion. The rates
of shoreline erosion vary from -2.4 ft/yr at Harbor Beach to -3.4 ft/yr at Tyson Street. These rates of
shoreline erosion are concerning since beach recreation opportunities are largely confined to this
stretch of shoreline due to limited dry beach south of Tyson Street. The highest rate of shoreline
erosion was -3.6 ft/yr measured at profile OS-1030, about 1,500 feet north of the Oceanside Pier and
shown in Figure 3-6. These results are a clear indication that the annual harbor dredging program is
insufficient to maintain beaches of North Oceanside.
400
450
500
550
600
650
700
750
800
850
900
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240Shoreline Position (m) Model Cell Number
1934 Survey1998 Survey2006 SurveySeawall
Pier SLR Groin Harbor[9]Seasonal fluctuations were generally small except near the mouths of San Luis Rey and Santa
Margarita Rivers.The San Luis Rey and Santa Margarita Rivers were dammed after the floods of
1916 and 1936/1938,respectively.These dams significantly reduced the amount of sand entering
the Oceanside littoral zone (USACE,2016).The shoreline in the City has changed dramatically over
the past century (Figure 3-4).Comparison of the 1934 and 1998 shoreline show the severe erosion
downcoast of the harbor during the 64-year period.Conversely,accretion is observed on the updrift
side of the harbor at Camp Pendleton.
SLRPierGmin HarborA900
g 850 —1934 Surveyc800—1998 Survey.3 750 —2006 Survey
'5 700 —Seawall
8 650
.2 600
E 550
O 500.C(I)450
400
0 10 20 30 40 50 60 70 80 90 100110120130140150160170180190 200 210 220 230 240
Model Cell Number
Figure 3-4.Historical Shoreline Positions in the City (USAGE 2015)
Recent shoreline change was evaluated using beach profile data collected by Coastal Frontiers
Corporation (CFC)from 1995 through 2018 and made available to the public on SANDAG’s website.
This data consists of surveyed beach profiles collected in fall and spring seasons on an annual basis.
Ten profiles within the study reach have been surveyed since 1995 providing useful data for
evaluating shoreline change over the last several decades.Two South Oceanside beach profiles
(08-947 and 08-915)were established for the RBSP projects and therefore only provide data before
and after these nourishment events.The location of these profiles are shown in Figure 3-6.The mean
sea level shoreline position data illustrate clear trends of shoreline change that have been organized
into three distinct reaches,discussed in this section.
3.4.1 North Oceanside
Shoreline change in this reach is characterized by beach profiles OS-1070 (Harbor Beach)through
08-1000 (South Strand,Tyson Street),all of which show a clear trend of shoreline erosion.The rates
of shoreline erosion vary from -2.4 nr at Harbor Beach to -3.4 ft/yr at Tyson Street.These rates of
shoreline erosion are concerning since beach recreation opportunities are largely confined to this
stretch of shoreline due to limited dry beach south of Tyson Street.The highest rate of shoreline
erosion was -3.6 ft/yr measured at profile OS-1030,about 1,500 feet north of the Oceanside Pier and
shown in Figure 3-6.These results are a clear indication that the annual harbor dredging program is
insufficient to maintain beaches of North Oceanside.
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3.4.2 South Oceanside
This reach of shoreline extends from Tyson Street to the Buena Vista Lagoon and includes beach
profiles OS-0930 through OS-0900. This reach of shoreline has historically been a narrow beach
almost entirely backed by a rock revetment with only temporary periods of dry beach after RBSP I
and II. The profile spacing and survey frequency is of limited use in characterizing shoreline change
trends along this reach. Google Earth aerial imagery is a useful tool to understand the shoreline
changes along this reach over the last two decades. These images illustrate the progressive loss of
sand along this reach, most of which has lacked a dry beach since 2014. Over the last several
decades, shoreline change along this reach has been limited by the revetment, another indication of
a persistent erosion trend.
Most regional shoreline change assessments prepared for SANDAG use profile OS-0930 to
represent this 2-mile reach of shoreline. Unfortunately, this profile is atypical of the south Oceanside
shoreline. OS-0930 is measured at Buccaneer Beach, the only location that is not backed by a
revetment along the stringline of development. This profile represents shoreline change at a gap in
the ~2-mile revetment in which the profile baseline is about 130-150 feet landward of the adjacent
revetments. Therefore, beach widths reported at this transect can be quite misleading. For example,
if an MSL beach width of 130 feet is reported at profile OS-0930, this means there is essentially no
dry beach throughout the 2-mile stretch of shoreline “represented” by this profile. A photograph
looking south from Buccaneer Beach in Fall 2017 (Figure 3-5) illustrates the typical beach condition
along the South Oceanside reach. Note, an MSL beach width of 58 feet was reported during the Fall
2017 survey at this location. The most notable shoreline changes observed in this reach were a result
of the RBSP I and II projects and are discussed in Section 4.3.
Figure 3-5. Fall 2017 Photograph looking south from Buccaneer Beach
Profile OS-0900 is located at the south end of Oceanside near Vista Way. This profile reflects a
transition zone between an erosional shoreline to an accretional shoreline. From 1995 through 2002 [Q]3.4.2 South Oceanside
This reach of shoreline extends from Tyson Street to the Buena Vista Lagoon and includes beach
profiles 08-0930 through OS-0900.This reach of shoreline has historically been a narrow beach
almost entirely backed by a rock revetment with only temporary periods of dry beach after RBSP l
and II.The profile spacing and survey frequency is of limited use in characterizing shoreline change
trends along this reach.Google Earth aerial imagery is a useful tool to understand the shoreline
changes along this reach over the last two decades.These images illustrate the progressive loss of
sand along this reach,most of which has lacked a dry beach since 2014.Over the last several
decades,shoreline change along this reach has been limited by the revetment,another indication of
a persistent erosion trend.
Most regional shoreline change assessments prepared for SANDAG use profile 08-0930 to
represent this 2-mile reach of shoreline.Unfortunately,this profile is atypical of the south Oceanside
shoreline.OS—0930 is measured at Buccaneer Beach,the only location that is not backed by a
revetment along the stringline of development.This profile represents shoreline change at a gap in
the ~2-mile revetment in which the profile baseline is about 130-150 feet landward of the adjacent
revetments.Therefore,beach widths reported at this transect can be quite misleading.For example,
if an MSL beach width of 130 feet is reported at profile OS-0930,this means there is essentially no
dry beach throughout the 2-mile stretch of shoreline “represented”by this profile.A photograph
looking south from Buccaneer Beach in Fall 2017 (Figure 3-5)illustrates the typical beach condition
along the South Oceanside reach.Note,an MSL beach width of 58 feet was reported during the Fall
2017 survey at this location.The most notable shoreline changes observed in this reach were a result
of the RBSP l and II projects and are discussed in Section 4.3.
Figure 3-5.Fall 2017 Photograph looking south from Buccaneer Beach
Profile OS—0900 is located at the south end of Oceanside near Vista Way.This profile reflects a
transition zone between an erosional shoreline to an accretional shoreline.From 1995 through 2002
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the shoreline position data indicate a trend of accretion. From 2002 through 2018 the shoreline
position data indicate a trend of erosion, at a rate of about -1.2 ft/yr.
3.4.3 North Carlsbad
This reach of shoreline extends from the Buena Vista Lagoon to the Agua Hedionda Lagoon and
includes beach profiles CB-0880 through CB-0830. These five profiles are spread evenly along this
reach of shoreline and indicate a dominant trend of accretion, dating back to 1995. Trends of
shoreline accretion range from +2.2 ft/yr at CB-0880 to +3.9 ft/yr at CB-0850 with all profiles
experiencing a gain of 100 feet or more beach width since the 1990s. Shoreline change at profile
CB-0850 is shown in Figure 3-6.
A few factors have likely contributed to the long-term trend of shoreline accretion along the North
Carlsbad reach. The north groin at Agua Hedionda has played a major role in retaining sand upcoast
in an extended fillet with a dry sand beach which averages 150-200 feet in width. Groins do not work
by themselves and require a supply of coarse-grained sand to retain a dry beach area. The RBSP I
and II projects provided a large supply of coarse-grained sand to this reach of shoreline. The
shoreline position data and aerial images indicate a large amount of the coarse-grained sand placed
in RBSP I and II at Oceanside and North Carlsbad remains in the fillet upcoast of this groin. The
trend of shoreline accretion at North Carlsbad is a good example of the lasting benefits provided by
the combination of a sand retention structure and a supply of coarse-grained sand.
[Q]the shoreline position data indicate a trend of accretion.From 2002 through 2018 the shoreline
position data indicate a trend of erosion,at a rate of about -1.2 nr.
3.4.3 North Carlsbad
This reach of shoreline extends from the Buena Vista Lagoon to the Agua Hedionda Lagoon and
includes beach profiles CB-0880 through CB-O830.These five profiles are spread evenly along this
reach of shoreline and indicate a dominant trend of accretion,dating back to 1995.Trends of
shoreline accretion range from +2.2 ft/yr at 08-0880 to +3.9 ft/yr at CB-0850 with all profiles
experiencing a gain of 100 feet or more beach width since the 19903.Shoreline change at profile
CB-0850 is shown in Figure 3-6.
A few factors have likely contributed to the long-term trend of shoreline accretion along the North
Carlsbad reach.The north groin at Agua Hedionda has played a major role in retaining sand upcoast
in an extended fillet with a dry sand beach which averages 150-200 feet in width.Groins do not work
by themselves and require a supply of coarse-grained sand to retain a dry beach area.The RBSP l
and II projects provided a large supply of coarse-grained sand to this reach of shoreline.The
shoreline position data and aerial images indicate a large amount of the coarse-grained sand placed
in RBSP l and II at Oceanside and North Carlsbad remains in the fillet upcoast of this groin.The
trend of shoreline accretion at North Carlsbad is a good example of the lasting benefits provided by
the combination of a sand retention structure and a supply of coarse-grained sand.
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Figure 3-6. Profile Location Map and Shoreline Change Trends in Study Reach
“9'“I North Oceanside,05-1030"DWMRBSFIBSMFill_1 350CFC2°"w”Harbor dredge placement
300 \\II
200 l —A
150 K“
100
ShorelinePosition(MSL)Erosion 1 rend,-3.6ftflyr
50
1995 2000 2005 2010 2015 2020
North Carlsbad,CB-850
350
300
250
200 Accretion trend,+3.9 ft/yr
150
100
ShorelinePosition(MSL)50
1995 2000 2005 2010 2015 2020
Err;HERE.@«mfi.
Figure 3-6.Profile Location Map and Shoreline Change Trends in Study Reach
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4. Synthesis of Coastal Challenges
A myriad of coastal challenges exist that have contributed to the erosion of City beaches and have
influenced coastal management decisions made over time. A summary of our understanding of the
challenges are provided in this section.
4.1 Oceanside Harbor Complex & Sediment Gradation
The largest factor contributing to Oceanside’s erosion problem results from a limited sediment supply
from updrift beaches as a result of the Oceanside Harbor complex. The breakwater acts as a littoral
barrier that only allows a portion of fine sediment to be transported around the breakwater into the
entrance channel. The coarse-grained fraction of sand in the beach profile is largely retained upcoast
of the harbor in a wide beach along MCB Camp Pendleton. Fine-grained sediment which makes its
way around the breakwater into the entrance channel is insufficient in quantity and quality to mitigate
the long-term trend of shoreline erosion affecting Oceanside’s beaches.
Native sediment on City beaches consists of fine sand to silt. Along the beach profile, fine sand with
a D50 of 0.2mm exists on the dry beach (i.e. above MLLW). The silty sand below MLLW has a lower
D50 of 0.1 to 0.05mm. These subtle changes in values represent a significant difference in beach
type and function. The coarser sand are not as easily mobilized by waves and form a dry beach,
while the finer sand is easily mobilized and is deposited in deeper waters where lesser currents exist
(Figure 4-1). [Q]Synthesis of Coastal Challenges
A myriad of coastal challenges exist that have contributed to the erosion of City beaches and have
influenced coastal management decisions made over time.A summary of our understanding of the
challenges are provided in this section.
4.1 Oceanside Harbor Complex &Sediment Gradation
The largest factor contributing to Oceanside’s erosion problem results from a limited sediment supply
from updrift beaches as a result of the Oceanside Harbor complex.The breakwater acts as a littoral
barrier that only allows a portion of fine sediment to be transported around the breakwater into the
entrance channel.The coarse-grained fraction of sand in the beach profile is largely retained upcoast
of the harbor in a wide beach along MCB Camp Pendleton.Fine-grained sediment which makes its
way around the breakwater into the entrance channel is insufficient in quantity and quality to mitigate
the long-term trend of shoreline erosion affecting Oceanside’s beaches.
Native sediment on City beaches consists of fine sand to silt.Along the beach profile,fine sand with
a D50 of 0.2mm exists on the dry beach (i.e.above MLLW).The silty sand below MLLW has a lower
D50 of 0.1 to 0.05mm.These subtle changes in values represent a significant difference in beach
type and function.The coarser sand are not as easily mobilized by waves and form a dry beach,
while the finer sand is easily mobilized and is deposited in deeper waters where lesser currents exist
(Figure 4-1).
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Figure 4-1. Comparison of Beach Type and Gradation North and South of
Oceanside Harbor
4.2 Limited Beach Gains from USACE Harbor Dredging Program
The current USACE sand placement program is limited in its ability to provide dry sandy beaches in
the City for the following reasons:
• Timing: Harbor dredging occurs in the Spring of every year, which marks the beginning of a
change in the wave climate in the City. The predominate wave energy shifts from the winter’s
northwest dominant approach angle to one out of the southwest. Waves from the southern
quadrant drive longshore currents and sediment to the north. Thus, placed sediment from
the harbor in the Spring has a high likelihood of being transported to the north (towards
harbor beaches)(Figure 4-2).
• Sediment Type: Sediment from the harbor is classified as a fine-grained sand. Fine-grained
sand is easily mobilized by waves and transported by longshore currents. Sand with these
characteristics form what is referred to as a submerged profile once in equilibrium (Figure
4-3). A submerged profile acts to dissipate wave energy but does not generally form a dry
sandy beach. Therefore, placed sand from this program does not achieve the City’s goal of
having a dry sand beach for recreation and coastal storm damage protection.
• Placement Location: In recent times sand has been placed mostly north of the pier due to
a combination of reasons described previously. Sand placement at these locations is
believed to mostly benefit northern beaches due to the northerly dominant longshore
transport direction during the time of placement. [Q]Camp Pendleton MCB-WpicalBeach Profile South Oceanside -1ypical Beach Profile
M.NoCoarseSand=NoDrybeach
Drybeach050>042mm
Submerged beachD50<0.2mm Submerged beach050<0.2mm
Figure 4-1.Comparison of Beach Type and Gradation North and South of
Oceanside Harbor
4.2 Limited Beach Gains from USAGE Harbor Dredging Program
The current USACE sand placement program is limited in its ability to provide dry sandy beaches inmeowforthefollowingreasons:
Timing:Harbor dredging occurs in the Spring of every year,which marks the beginning of a
change in the wave climate in the City.The predominate wave energy shifts from the winter’s
northwest dominant approach angle to one out of the southwest.Waves from the southern
quadrant drive longshore currents and sediment to the north.Thus,placed sediment from
the harbor in the Spring has a high likelihood of being transported to the north (towards
harbor beaches)(Figure 4-2).
Sediment Type:Sediment from the harbor is classified as a fine-grained sand.Fine-grained
sand is easily mobilized by waves and transported by longshore currents.Sand with these
characteristics form what is referred to as a submerged profile once in equilibrium (Figure
4-3).A submerged profile acts to dissipate wave energy but does not generally form a dry
sandy beach.Therefore,placed sand from this program does not achieve the City’s goal of
having a dry sand beach for recreation and coastal storm damage protection.
Placement Location:In recent times sand has been placed mostly north of the pier due to
a combination of reasons described previously.Sand placement at these locations is
believed to mostly benefit northern beaches due to the northerly dominant longshore
transport direction during the time of placement.
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• Placement Methods: Dredged sand is transported from the harbor to City beaches via a
sand/water slurry. The current contractor uses a large dredge that transports large volumes
of sand quickly. Typical construction methods for beach nourishment projects entail the use
of training dikes to slow the velocity of the hydraulic slurry to allow sediment to deposit on
the beach. Current practice does not entail the regular use of these training dikes. Sediment
is discharged in the intertidal and dozers scrape up deposited material just downdrift of the
pipeline (Figure 4-4).
All these factors lessen the ability of this placed sand to benefit and “feed” beaches to the south.
Figure 4-2. USACE Sand Placement Relative to Seasonal Longshore Transport
Schematic
o Placement Methods:Dredged sand is transported from the harbor to City beaches via a
sand/water slurry.The current contractor uses a large dredge that transports large volumes
of sand quickly.Typical construction methods for beach nourishment projects entail the use
of training dikes to slow the velocity of the hydraulic slurry to allow sediment to deposit on
the beach.Current practice does not entail the regular use of these training dikes.Sediment
is discharged in the intertidal and dozers scrape up deposited material just downdrift of the
pipeline (Figure 4-4).
All these factors lessen the ability of this placed sand to benefit and “feed”beaches to the south.
Legend
Approximate201521120
..2051-2020 ,"Avg.~193.2oo c7Y -‘7
Dredged March Ma
1994-2020 OverallAvg.=253,000 CY
0 410 320 1230 1840 ssw to sw
—:—:'*‘3’Dominant Wave DirectionmgmmApril-Oct.munaim-owflush-Innocent“Hvswsrm
Figure 4-2.USACE Sand Placement Relative to Seasonal Longshore Transport
Schematic
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Figure 4-3. Relationship between Native and Beach Fill Grain Size and Beach
Performance (derived from Dean, 1991)
[Q]0 Fill grain size >native grain size
Coarse sand remains
higher on beach profile
AAAAAAAAAAAAAA u (Most Dry Beach)
9 Fill grain size =native grain size
Sand dispersed across
entire profile
(Some Dry Beach)
0 Fill grain size <native grain size
Fine sand settles lower onAAAAAAbeachprofile
(No Dry Beach)
Figure 4-3.Relationship between Native and Beach Fill Grain Size and Beach
Performance (derived from Dean,1991)
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Figure 4-4. Current USACE Placement Methods
4.3 Poor Performance of Regional Beach Fills
An analysis of the performance of prior Regional Beach Sand Projects were conducted as part of this study
using aerial imagery and monitoring data available from SANDAG. While these projects produced regional
benefits by adding sand to a sediment starved coastline, the benefits along Oceanside beaches were short-
lived, with most of the material moving downcoast within a few years after placement.
Mean high water (MHW) shoreline positions were traced from aerial imagery from 2006 to 2019 to
understand shoreline change before and after the RBSP II project. A total of 11 shorelines were recorded
within this timeframe for a study area that spanned from Oceanside Harbor to the Agua Hedionda North
Jetty. The shorelines were analyzed via Digital Shoreline Analysis System (DSAS) from which annual
trends in shoreline movement were determined. The placement locations can be seen in
Figure 4-5 and clearly illustrate the evolution of these beach fills and accumulation of sand along North
Carlsbad. By May 2015, about 2.5 years post-fill, the shoreline position at the placement site had retreated
to pre-RBSP II conditions.
The RBSP II beach profile monitoring data provide another source of information to evaluate the local
performance of this project. Profile OS-0947 was established just prior to RBSP II and is the only profile
within the sand placement area. Beach profiles and mean sea level (MSL) shoreline position are plotted in
Figure 4-6 at this transect. The beach profiles indicate some accumulation of sand lower in the beach profile
at depths of -2 to -10 feet, mean lower low water (MLLW) which is typical as wave action disperses the
initial fill in both cross-shore and longshore directions. The upper profile shows a steady loss of dry beach
width which appears to have largely moved in the alongshore direction to the south. [Q]4.3 Poor Performance of Regional Beach Fills
An analysis of the performance of prior Regional Beach Sand Projects were conducted as part of this study
using aerial imagery and monitoring data available from SANDAG.While these projects produced regional
benefits by adding sand to a sediment starved coastline,the benefits along Oceanside beaches were short-
lived,with most of the material moving downcoast within a few years after placement.
Mean high water (MHW)shoreline positions were traced from aerial imagery from 2006 to 2019 to
understand shoreline change before and after the RBSP II project.A total of 11 shorelines were recorded
within this timeframe for a study area that spanned from Oceanside Harbor to the Agua Hedionda North
Jetty.The shorelines were analyzed via Digital Shoreline Analysis System (DSAS)from which annual
trends in shoreline movement were determined.The placement locations can be seen in
Figure 4-5 and clearly illustrate the evolution of these beach fills and accumulation of sand along North
Carlsbad.By May 2015,about 2.5 years post-fill,the shoreline position at the placement site had retreated
to pre-RBSP ||conditions.
The RBSP ||beach profile monitoring data provide another source of information to evaluate the local
performance of this project.Profile 08-0947 was established just prior to RBSP II and is the only profile
within the sand placement area.Beach profiles and mean sea level (MSL)shoreline position are plotted in
Figure 4-6 at this transect.The beach profiles indicate some accumulation of sand lower in the beach profile
at depths of -2 to -10 feet,mean lower low water (MLLW)which is typical as wave action disperses the
initial fill in both cross-shore and longshore directions.The upper profile shows a steady loss of dry beach
width which appears to have largely moved in the alongshore direction to the south.
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Profiles OS-0930, OS-0915 and OS-0900 are located downdrift of the initial fill but did not perform any
better than OS-0947. Profile OS-0930 showed a similar response to OS-0947 (i.e. only temporary dry beach
area) and profiles OS-0915 and OS-0900 showed only incremental gains in beach width from RBSP II that
were also short-lived. Analysis of profiles updrift of the Oceanside fill showed no evidence of beach width
increases from the RBSP II project.
Based on this analysis, a nourishment program on the scale and frequency of RBSP I and II would not be
a viable solution for North and South Oceanside without some type of sand retention system. RBSP I and
II projects provided long lasting benefits to North Carlsbad due largely to the sand retention provided by the
north groin at Agua Hedionda lagoon.
[Q]Profiles 08-0930,08-0915 and 08-0900 are located downdrift of the initial fill but did not perform any
better than 08-0947.Profile 08-0930 showed a similar response to 08-0947 (i.e.only temporary dry beach
area)and profiles 08-0915 and 08-0900 showed only incremental gains in beach width from RBSP II that
were also short-lived.Analysis of profiles updrift of the Oceanside fill showed no evidence of beach width
increases from the RBSP II project.
Based on this analysis,a nourishment program on the scale and frequency of RBSP l and II would not be
a viable solution for North and South Oceanside without some type of sand retention system.RBSP |and
II projects provided long lasting benefits to North Carlsbad due largely to the sand retention provided by the
north groin at Agua Hedionda lagoon.
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Figure 4-5. Post RBSP II Shoreline Positions
Oceanside Fill
N. Carlsbad Fill [9]Post RBSP II:2012-2015 Shoreline Positions
—m —2°12 _2°13 Oceanside Fill eé,
9 ‘5"—2014 —2015 ‘290 6:9
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20 ShorelinePosition(m)Figure 4-5.Post RBSP II Shoreline Positions
GHD |Beach Sand Replenishment &Retention Device Project |June 2021 |Page 29Jan. 4, 2022 Item 4 Page 43 of 229
GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 30
Figure 4-6. RBSP II Performance at South Oceanside [9]Elevation(Feet,MLLW)ShorelinePosition(MSL)05-947
350
300 K
25o \\
150
100
2010 2011 2012 2013
200
2014 2015 2016 2017 2018
05-947 Spring 2012-2015
---------May 2012 (Pre RBSP ll)
—Oct 2012 (RBSP ll)
May 2013
May 2014
May 2015
300 400 500 600 700 800 900 1000
Cross—Shore Distance {Feet Seaward of Transect Orgin)
Figure 4-6.RBSP II Performance at South Oceanside
GHD |Beach Sand Replenishment &Retention Device Project |June 2021 |Page 30Jan. 4, 2022 Item 4 Page 44 of 229
GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 31
4.1 Difficulty Reaching Social, Political & Regulatory Consensus
Coastal management decisions are challenging to reach consensus on. Potential downdrift impacts,
costs, environmental and recreational impacts and concerns about establishment of precedent being
some of the biggest concerns typically voiced when a proposal is being considered. The various
stakeholder groups, agencies and community user groups have varying missions and viewpoints on
how beaches should be managed. All user groups are sensitive to potential changes.
The difficulty in reaching consensus was exemplified in Saving California’s Coast (O’Hara & Graves,
1991), which documented how a similar study to this one was carried out in Oceanside in the 1980’s.
The study found a series of shore-perpendicular rock groins to be preferrable from a technical and
cost perspective to restore eroding beaches in the City. However, the option was rejected by the
community and elected officials fueled by local criticism of the Project starting a “chain reaction” of
similar structures down the coastline. The USACE then put forward the next highest scoring option,
the breakwater option. This option was met with intense opposition from local surfing groups due to
the detrimental effects the structures could have on surfing resources in the City. The Experimental
Sand Bypass option was born as a compromise that most groups could support but ultimately failed
for a number of reasons. Most notable of these reasons from a consensus building perspective
included MCB Camp Pendleton’s stipulation that the Project did not encroach on their property and
consistent funding from the USACE.
Today the City is grappling with the same issue of a persistent eroding shoreline; however, the
condition of the shoreline or “the problem” has gotten worse. Consensus-building will again be a
challenge in moving any of the alternatives discussed in this report forward. Key agencies and entities
that will need to be engaged with and the issues to resolve are outlined below:
• MCB Camp Pendleton: Sand from the northern breakwater fillet represents the highest
quality, sustainable source of sand to the City. The construction of the harbor and subsequent
accumulation of sand at this location has had a clearly documented impact on City beaches.
• Surfrider Foundation: Measures to ensure preservation of existing surfing resources.
• California Coastal Commission: Issues surrounding Coastal Act resource preservation,
including beach access, recreation, and coastal habitats.
• Adjacent property owners and the City of Carlsbad: Concerns surrounding downdrift
impacts and mitigation.
Many of these agencies have already been engaged as part of this feasibility study. Numerous public,
stakeholder and resource agency outreach events were conducted during the period of study.
Meetings were held with the following entities to date:
• Resource agencies:
o California Coastal Commission (CCC)
o Regional Water Quality Control Board (RWQCB)
o U.S. Army Corps of Engineers (LA District) [$14.1 Difficulty Reaching Social,Political &Regulatory Consensus
Coastal management decisions are challenging to reach consensus on.Potential downdrift impacts,
costs,environmental and recreational impacts and concerns about establishment of precedent being
some of the biggest concerns typically voiced when a proposal is being considered.The various
stakeholder groups,agencies and community user groups have varying missions and viewpoints on
how beaches should be managed.All user groups are sensitive to potential changes.
The difficulty in reaching consensus was exemplified in Saving California’s Coast (O’Hara &Graves,
1991),which documented how a similar study to this one was carried out in Oceanside in the 1980’s.
The study found a series of shore-perpendicular rock groins to be preferrable from a technical and
cost perspective to restore eroding beaches in the City.However,the option was rejected by the
community and elected officials fueled by local criticism of the Project starting a “chain reaction”of
similar structures down the coastline.The USACE then put forward the next highest scoring option,
the breakwater option.This option was met with intense opposition from local surfing groups due to
the detrimental effects the structures could have on surfing resources in the City.The Experimental
Sand Bypass option was born as a compromise that most groups could support but ultimately failed
for a number of reasons.Most notable of these reasons from a consensus building perspective
included MCB Camp Pendleton’s stipulation that the Project did not encroach on their property and
consistent funding from the USACE.
Today the City is grappling with the same issue of a persistent eroding shoreline;however,the
condition of the shoreline or “the problem”has gotten worse.Consensus-building will again be a
challenge in moving any of the alternatives discussed in this report fonNard.Key agencies and entities
that will need to be engaged with and the issues to resolve are outlined below:
0 MCB Camp Pendleton:Sand from the northern breakwater fillet represents the highest
quality,sustainable source of sand to the City.The construction of the harbor and subsequent
accumulation of sand at this location has had a clearly documented impact on City beaches.
0 Surfrider Foundation:Measures to ensure preservation of existing surfing resources.
0 California Coastal Commission:Issues surrounding Coastal Act resource preservation,
including beach access,recreation,and coastal habitats.
o Adjacent property owners and the City of Carlsbad:Concerns surrounding downdrift
impacts and mitigation.
Many of these agencies have already been engaged as part of this feasibility study.Numerous public,
stakeholder and resource agency outreach events were conducted during the period of study.
Meetings were held with the following entities to date:
0 Resource agencies:
0 California Coastal Commission (CCC)
0 Regional Water Quality Control Board (RWQCB)
0 US.Army Corps of Engineers (LA District)
GHD |Beach Sand Replenishment &Retention Device Project |June 2021 |Page 31Jan. 4, 2022 Item 4 Page 45 of 229
GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 32
• Stakeholders:
o Save Our Sand (SOS)
o Surfrider Foundation
o Resilient Cities Catalyst
o San Diego Regional Climate Collaborative
o SANDAG Shoreline Preservation Workgroup
• City Public Outreach Event (2)
• City planning, public works and engineering
5. Data Review and Assimilation
5.1 Coastal Studies
As a result of the harbor development and the onset of erosion of downdrift beaches, the City’s
shoreline has been extensively studied over the last 80 years. This study included a review of available
coastal studies to understand coastal conditions but also options considered or carried out in the past.
Of the studies reviewed, the following were found to be key to this study:
• USACE Special Shoreline Study (2016 - ongoing): Evaluation of a number of nourishment
and sand retention options. Groins and beach nourishment were determined to the favored
alternatives. Due to a lack of funding, the study is unfinished.
• Oceanside Harbor and Beach, California Design of Structures for Harbor Improvement
and Beach Erosion Control (1980): Examined 88 different options of harbor improvements
and 16 beach sand retention concepts that would mitigate the loss of sand along the beaches
and sand shoaling within the harbor. These improvements were tested in scaled physical
model. The study recommended six to ten, 800’ long groins, spaced 1,000 feet apart and
tapering to the south or a 4,900-foot long breakwater, 800 feet offshore with groins on either
side. The preferred groin option is shown in Figure 5-1.
• Saving California’s Coast, (O’Hara & Graves, 1991): A history of the social and political
pressures leading to the selection of a preferred alternative from the USACE’s 1980 study.
The preferred alternative shifted from the groin plan (initially) to the breakwater plan
(secondarily) and then to the sand bypass pilot as a fallback, non-structural option.
For a complete list of literature reviewed and summaries of key findings, please see Data Gathering
Memorandum (Appendix A). [Q]Stakeholders:
0 Save Our Sand (SOS)
o Surfrider Foundation
0 Resilient Cities Catalyst
0 San Diego Regional Climate Collaborative
o SANDAG Shoreline Preservation Workgroup
City Public Outreach Event (2)
City planning,public works and engineering
Data Review and Assimilation
5.1 Coastal Studies
As a result of the harbor development and the onset of erosion of downdrift beaches,the City’s
shoreline has been extensively studied over the last 80 years.This study included a review of available
coastal studies to understand coastal conditions but also options considered or carried out in the past.
Of the studies reviewed,the following were found to be key to this study:
USACE Special Shoreline Study (2016 -ongoing):Evaluation of a number of nourishment
and sand retention options.Groins and beach nourishment were determined to the favored
alternatives.Due to a lack of funding,the study is unfinished.
Oceanside Harbor and Beach,California Design of Structures for Harbor Improvement
and Beach Erosion Control (1980):Examined 88 different options of harbor improvements
and 16 beach sand retention concepts that would mitigate the loss of sand along the beaches
and sand shoaling within the harbor.These improvements were tested in scaled physical
model.The study recommended six to ten,800’long groins,spaced 1,000 feet apart and
tapering to the south or a 4,900-foot long breakwater,800 feet offshore with groins on either
side.The preferred groin option is shown in Figure 5-1.
Saving California’s Coast,(O’Hara &Graves,1991):A history of the social and political
pressures leading to the selection of a preferred alternative from the USACE’s 1980 study.
The preferred alternative shifted from the groin plan (initially)to the breakwater plan
(secondarily)and then to the sand bypass pilot as a fallback,non-structural option.
For a complete list of literature reviewed and summaries of key findings,please see Data Gathering
Memorandum (Appendix A).
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GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 33
Figure 5-1. Recommended Groin Concept (USACE, 1980)
5.2 Sand Bypassing Project Examples
Several sand bypassing systems were reviewed for their applicability and utility in resolving the erosion
issues in the City. These systems were reviewed after gaining a fundamental understanding of the
challenges faced with the Experimental Sand Bypassing Project in Oceanside, of which many
references were reviewed. The locations and systems reviewed are summarized below:
• Tweed River Bypass System (Queensland, Australia): Large, fixed trestle sand bypass
system that transports 650,000 CY per year to downdrift beaches.
• Noosa Sandshifter System (Sunshine Coast, Australia): Small, semi-fixed sand bypass
system that backpasses 80,000 CY per year to updrift locations to protect coastal
development. A buried intake and fluidizer in the foreshore mobilizes sediment.
• Peninsula Beach Long Beach Bypass System (Long Beach, California): Small dredge
system to backpass sand along Peninsula Beach. Concept is being piloted in lieu of existing
trucked backpass system.
• Indian River Inlet System (Bethany Beach, Delaware): Small semi-fixed system that
bypasses about 100,000 CY per year of sand around an inlet to downdrift beaches. System
utilizes a crane manipulated cutter head, pump house and fixed sand pipeline distribution
system. The system was constructed and is operated by the USACE. [Q]PIERll,_...
100400I
T
'—MLLW flu...
—_———CROW EL'HOJJ:2
/
_L.,_.._ra —
”—42 ”‘—
_’-—————_———"—
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’f‘./——-—————-—’a—r’fl—uI
ELEMENTS 0F PLAN 9-93W
100 0 ID”
I“#0
NOTE:CONTOURS AND ELEVATIONS ARE \é
IN FEET REFERRED TO MEAN ’PROTOTYPE
LOWER LOW WATER.MODEL
Figure 5-1.Recommended Groin Concept (USACE,1980)
5.2 Sand Bypassing Project Examples
Several sand bypassing systems were reviewed for their applicability and utility in resolving the erosion
issues in the City.These systems were reviewed after gaining a fundamental understanding of the
challenges faced with the Experimental Sand Bypassing Project in Oceanside,of which many
references were reviewed.The locations and systems reviewed are summarized below:
Tweed River Bypass System (Queensland,Australia):Large,fixed trestle sand bypass
system that transports 650,000 CY per year to downdrift beaches.
Noosa Sandshifter System (Sunshine Coast,Australia):Small,semi-fixed sand bypass
system that backpasses 80,000 CY per year to updrift locations to protect coastal
development.A buried intake and fluidizer in the foreshore mobilizes sediment.
Peninsula Beach Long Beach Bypass System (Long Beach,California):Small dredge
system to backpass sand along Peninsula Beach.Concept is being piloted in lieu of existing
trucked backpass system.
Indian River Inlet System (Bethany Beach,Delaware):Small semi-fixed system that
bypasses about 100,000 CY per year of sand around an inlet to downdrift beaches.System
utilizes a crane manipulated cutter head,pump house and fixed sand pipeline distribution
system.The system was constructed and is operated by the USACE.
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GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 34
• Santa Barbara Sand Distribution System (Santa Barbara, California): Harbor dredging
program that utilizes a buried pipeline distribution system. Dredging system moves 200,000
CY per year from the harbor channels to downdrift beaches.
5.3 Sand Retention Project Examples
The following sand retention projects were reviewed for reference for their applicability to resolving
the erosion issues in the City. The retention projects reviewed are summarized below:
• Upham Beach Groins, Pinellas County, FL: Geotextile, T-head groins were piloted
and studied by a local university for a five-year period. The geotextile groins were
replaced with rock at the end of the five-year period. Project approach was mirrored for
this study.
• Palm Beach Surfing Reef, Queensland, Australia: Submerged multi-purpose artificial
reef for beach stabilization and surfing. Constructed in September 2019.
• Chevron Groin & Pratt’s Reef, Dockweiler Beach, CA: Construction of an 800-foot
long groin and subsequent construction of Pratt’s Reef, an artificial surfing reef. The reef
was constructed to offset surfing impacts from the Chevron groin and was comprised of
geotextile bags. The project was deemed unsuccessful at creating surfing waves and
was later removed.
• Agua Hedionda Lagoon Jetties, Carlsbad, CA: Two series of about 400-foot long
jetties at Tamarack Beach and warm water jetties just downdrift of Oceanside beach.
Dredged sand from the lagoon is placed various locations within the jetty compartments
contingent on beach conditions at the time of dredging.
• Newport Beach Groins, City of Newport Beach, CA: Eight, about 500-foot long rock
groins spaced about 900 feet apart in southern Newport Beach.
• Imperial Beach Groins, City of Imperial Beach, CA: Two, 300 to 500-foot long rock
groins spaced about 1,300 feet apart in northern Imperial Beach.
[Q]0 Santa Barbara Sand Distribution System (Santa Barbara,California):Harbor dredging
program that utilizes a buried pipeline distribution system.Dredging system moves 200,000
CY per year from the harbor channels to downdrift beaches.
5.3 Sand Retention Project Examples
The following sand retention projects were reviewed for reference for their applicability to resolving
the erosion issues in the City.The retention projects reviewed are summarized below:
Upham Beach Groins,Pinellas County,FL:Geotextile,T-head groins were piloted
and studied by a local university for a five-year period.The geotextile groins were
replaced with rock at the end of the five-year period.Project approach was mirrored for
this study.
Palm Beach Surfing Reef,Queensland,Australia:Submerged multi-purpose artificial
reef for beach stabilization and surfing.Constructed in September 2019.
Chevron Groin &Pratt’s Reef,Dockweiler Beach,CA:Construction of an 800-foot
long groin and subsequent construction of Pratt’s Reef,an artificial surfing reef.The reef
was constructed to offset surfing impacts from the Chevron groin and was comprised of
geotextile bags.The project was deemed unsuccessful at creating surfing waves and
was later removed.
Agua Hedionda Lagoon Jetties,Carlsbad,CA:Two series of about 400-foot long
jetties at Tamarack Beach and warm water jetties just downdrift of Oceanside beach.
Dredged sand from the lagoon is placed various locations within the jetty compartments
contingent on beach conditions at the time of dredging.
Newport Beach Groins,City of Newport Beach,CA:Eight,about 500-foot long rock
groins spaced about 900 feet apart in southern Newport Beach.
Imperial Beach Groins,City of Imperial Beach,CA:Two,300 to 500-foot long rock
groins spaced about 1,300 feet apart in northern Imperial Beach.
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6. Alternatives
Based on our understanding of the coastal setting and challenges in the City, four action alternatives
were conceived that meet the City’s design guidelines of protecting City beaches from long-term
shoreline erosion. Furthermore, the alternatives must be environmental sensitive, financially feasible
and have a reasonable chance of being approved. These alternatives were compared against a no
action “No Project” scenario for context over an assumed design life of 20 years. Note that the
proposed alternatives have varying levels of performance (i.e. retention of a dry sandy beach) and is
a key difference, as discussed further in this report.
6.1 Pilot Approach
In attempt to overcome the significant social, political and regulatory hurdles surrounding the use of
sand retention strategies, the proposed Project approach is start with a small-scale pilot in a
representative and impacted segment of coastline in the City. The pilot could then be monitored and
expanded or adapted contingent on success. The South Strand (i.e. between the pier and Wisconsin
Avenue) is recommended as the pilot reach for the following reasons:
• Erosion impacted area (absence of dry beach most of the year);
• Popularity of the area – beaches, parks and walking path along the roadway (significant public
benefit); and
• City ownership of landside right-of-way (South Strand Roadway and infrastructure).
The approach would be to implement one of the proposed sand retention alternatives within this reach
and intensively monitor the Project for a period of about five years. During this time, monitoring of
potential impacts will take place with a focus on changes (positive or negative, from an established
baseline condition) to downdrift beaches, coastal resources and surfing. Should impacts be realized,
the pilot will be modified in attempt to lessen or mitigate them in close coordination with the City,
stakeholders and resource agencies. Potential modifications could range from changes to the amount
and location of placed sand to physical changes to the retention structures (removal or addition of
rock). Should impacts not be able to be mitigated over a period of adequate time for scientific analysis,
complete removal of structures would be considered. Project funding and permits will be crafted such
that these modifications could occur in a timely manner.
6.2 No Project
The No Project alternative is continuation of the status quo and is being considered for comparative
purposes against action alternatives. In this alternative the Corps Harbor Maintenance Program
continues unaltered in terms of volumes (i.e. average of 250k CY/yr) and location of placement (sand
generally placed from the pier north). The City continues to participate in regional beach nourishment
projects, similar to SANDAG’s RBSP which occur on an ad-hoc basis. The beach nourishment projects
deliver about 300,000 CY of sand on a frequency of about every 10 years. [Q]Alternatives
Based on our understanding of the coastal setting and challenges in the City,four action alternatives
were conceived that meet the City’s design guidelines of protecting City beaches from long-term
shoreline erosion.Furthermore,the alternatives must be environmental sensitive,financially feasible
and have a reasonable chance of being approved.These alternatives were compared against a no
action “No Project”scenario for context over an assumed design life of 20 years.Note that the
proposed alternatives have varying levels of performance (i.e.retention of a dry sandy beach)and is
a key difference,as discussed further in this report.
6.1 Pilot Approach
In attempt to overcome the significant social,political and regulatory hurdles surrounding the use of
sand retention strategies,the proposed Project approach is start with a small-scale pilot in a
representative and impacted segment of coastline in the City.The pilot could then be monitored and
expanded or adapted contingent on success.The South Strand (i.e.between the pier and Wisconsin
Avenue)is recommended as the pilot reach for the following reasons:
0 Erosion impacted area (absence of dry beach most of the year);
c Popularity of the area —beaches,parks and walking path along the roadway (significant public
benefit);and
0 City ownership of landside right-of-way (South Strand Roadway and infrastructure).
The approach would be to implement one of the proposed sand retention alternatives within this reach
and intensively monitor the Project for a period of about five years.During this time,monitoring of
potential impacts will take place with a focus on changes (positive or negative,from an established
baseline condition)to downdrift beaches,coastal resources and surfing.Should impacts be realized,
the pilot will be modified in attempt to lessen or mitigate them in close coordination with the City,
stakeholders and resource agencies.Potential modifications could range from changes to the amount
and location of placed sand to physical changes to the retention structures (removal or addition of
rock).Should impacts not be able to be mitigated over a period of adequate time for scientific analysis,
complete removal of structures would be considered.Project funding and permits will be crafted such
that these modifications could occur in a timely manner.
6.2 No Project
The No Project alternative is continuation of the status quo and is being considered for comparative
purposes against action alternatives.In this alternative the Corps Harbor Maintenance Program
continues unaltered in terms of volumes (i.e.average of 250k CY/yr)and location of placement (sand
generally placed from the pier north).The City continues to participate in regional beach nourishment
projects,similar to SANDAG’s RBSP which occur on an ad-hoc basis.The beach nourishment projects
deliver about 300,000 CY of sand on a frequency of about every 10 years.
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6.3 Alternative 1: Beach Nourishment
The Beach Nourishment Alternative assumes a more aggressive beach nourishment program is
carried out by the City or region. The program would deliver 300,000 CY of sand to City beaches at a
consistent frequency of every five years; approximately doubling the frequency of the existing
placement. The program would identify and utilize coarse gradation sand (i.e. d50 greater than 0.3
mm) such that the placed sediment would benefit the subaerial beach (i.e. dry beach). By delivering
more sand at a higher frequency, the beach nourishment alternative would seek to improve beach
widths within the pilot reach.
Sand placement would be identical to RBSP II for environmental and regulatory efficiency (Figure 6-1).
Specially, details regarding the beach nourishment alternative are below:
• Sand placed just south of Seagaze Drive to Oceanside Boulevard (approximately 4,700 feet
in length)
• Build beach berm at an elevation of +13’ MLLW
• Beach berm will be 90 to 200 feet in width
6.4 Alternative 2: Groins
The Groins alternative assumes four, 600-foot long, rubble mound groins spaced 1,000 feet apart
along the Pilot Reach (Figure 6-2). The proposed groins are shore-perpendicular and would connect
to the seawall/rock revetment on the landward side to prevent loss of sand around the structure. The
groin structures will be comprised of 4-to-10-ton rock placed with a consistent crest elevation of 10’
MLLW.
The groins would trap sand moving in the longshore direction, creating sediment fillets against the
structures on the downdrift side of the predominate longshore sediment transport. The salient
formation within the groin compartment will fluctuate seasonally as wave energy shifts between
northern and southern approach directions.
Beach nourishment is proposed within this alternative, both as prefill (to fill groin compartments) and
at a renourishment interval to maintain beach widths. An initial placement volume of 300,000 CY is
proposed, identical to Alternative 1. The beach nourishment placement footprint is also varies from
Alternative 1 in that it carries a consistent width of 100 feet. Renourishment is proposed at 5-year
frequency; however, placement volumes for renourishment would be reduced over time since more
sand would be retained within the groin field. Renourishment volumes would be reduced to 150,000
CY based on the results of the numerical modeling of this option (Section 8).
6.5 Alternative 3: San Luis Rey Groin Extension
Alternative 3 proposes to extend the existing San Luis Rey Groin 350’ seaward (Figure 6-3). This
alternative would place large rock armor stone (approx. 10 ton) to build out the groin. Beach
nourishment is proposed within this alternative, identical in terms of initial and renourishment
placement volumes to the Alternative 1. [$16.3 Alternative 1:Beach Nourishment
The Beach Nourishment Alternative assumes a more aggressive beach nourishment program is
carried out by the City or region.The program would deliver 300,000 CY of sand to City beaches at a
consistent frequency of every five years;approximately doubling the frequency of the existing
placement.The program would identify and utilize coarse gradation sand (i.e.d50 greater than 0.3
mm)such that the placed sediment would benefit the subaerial beach (i.e.dry beach).By delivering
more sand at a higher frequency,the beach nourishment alternative would seek to improve beach
widths within the pilot reach.
Sand placement would be identical to RBSP II for environmental and regulatory efficiency (Figure 6-1).
Specially,details regarding the beach nourishment alternative are below:
0 Sand placed just south of Seagaze Drive to Oceanside Boulevard (approximately 4,700 feet
in length)
0 Build beach berm at an elevation of +13’MLLW
0 Beach berm will be 90 to 200 feet in width
6.4 Alternative 2:Groins
The Groins alternative assumes four,GOO-foot long,rubble mound groins spaced 1,000 feet apart
along the Pilot Reach (Figure 6-2).The proposed groins are shore-perpendicular and would connect
to the seawall/rock revetment on the landward side to prevent loss of sand around the structure.The
groin structures will be comprised of 4-to-10-ton rock placed with a consistent crest elevation of 10’
MLLW.
The groins would trap sand moving in the longshore direction,creating sediment fillets against the
structures on the downdrift side of the predominate longshore sediment transport.The salient
formation within the groin compartment will fluctuate seasonally as wave energy shifts between
northern and southern approach directions.
Beach nourishment is proposed within this alternative,both as prefill (to fill groin compartments)and
at a renourishment interval to maintain beach widths.An initial placement volume of 300,000 CY is
proposed,identical to Alternative 1.The beach nourishment placement footprint is also varies from
Alternative 1 in that it carries a consistent width of 100 feet.Renourishment is proposed at 5-year
frequency;however,placement volumes for renourishment would be reduced over time since more
sand would be retained within the groin field.Renourishment volumes would be reduced to 150,000
CY based on the results of the numerical modeling of this option (Section 8).
6.5 Alternative 3:San Luis Rey Groin Extension
Alternative 3 proposes to extend the existing San Luis Rey Groin 350’seaward (Figure 6-3).This
alternative would place large rock armor stone (approx.10 ton)to build out the groin.Beach
nourishment is proposed within this alternative,identical in terms of initial and renourishment
placement volumes to the Alternative 1.
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The groin extension would seek to capture sand moving northerly before being deposited in the
Oceanside Harbor. Growth of the existing sediment fillet along the southern end of the groin is
anticipated. This could either benefit beaches downdrift of this structure or this alternative could be
combined with a sand transfer option to “trap” sand in this location. Trapped sand would then be
transported to southern beaches in need.
6.6 Alternative 4: Multi-Purpose Artificial Reef
The Multi-purpose Artificial Reef alternative assumes two, 1,000-foot long, rubble mound reefs spaced
1,200 feet apart along the Pilot Reach (Figure 6-4). The reefs would have emergent and submergent
crest sections along their lengths to both reflect and focus wave energy, respectively. Beach
nourishment is proposed within this alternative, both as prefill and at a renourishment rate. An initial
placement volume of 300,000 CY is proposed initially, identical to the other alternatives. However, the
renourishment volume would be 150,000 CY at a 5-year interval, which is the lowest of the
alternatives. This is based on the effectiveness of the structures at sand retention based on the
numerical modeling results (Section 8).
The multi-purpose reefs would effectively function as a detached breakwater, which provides
significant reductions in wave energy and longshore transport in their lee. Sand would deposit behind
these structures in the form of a salient or tombolo based on design specific parameters to be refined
during the next phase. The edges of the structure are proposed to be submerged reefs where waves
could shoal and be ideally surfed. The prediction of surfing improvements (or impacts) is both
subjective and an emerging science; thus, is difficult to quantify. Typical wave approach directions,
typical surfzone and nearshore slopes and peel angles for desirable waves were consulted to generate
the conceptual design of the reef edges (Figure 6-5). [Q]The groin extension would seek to capture sand moving northerly before being deposited in the
Oceanside Harbor.Growth of the existing sediment fillet along the southern end of the groin is
anticipated.This could either benefit beaches downdrift of this structure or this alternative could be
combined with a sand transfer option to “trap”sand in this location.Trapped sand would then be
transported to southern beaches in need.
6.6 Alternative 4:Multi-Purpose Artificial Reef
The Multi-purpose Artificial Reef alternative assumes two,1,000-foot long,rubble mound reefs spaced
1,200 feet apart along the Pilot Reach (Figure 6-4).The reefs would have emergent and submergent
crest sections along their lengths to both reflect and focus wave energy,respectively.Beach
nourishment is proposed within this alternative,both as prefill and at a renourishment rate.An initial
placement volume of 300,000 CY is proposed initially,identical to the other alternatives.However,the
renourishment volume would be 150,000 CY at a 5-year interval,which is the lowest of the
alternatives.This is based on the effectiveness of the structures at sand retention based on the
numerical modeling results (Section 8).
The multi-purpose reefs would effectively function as a detached breakwater,which provides
significant reductions in wave energy and longshore transport in their lee.Sand would deposit behind
these structures in the form of a salient or tombolo based on design specific parameters to be refined
during the next phase.The edges of the structure are proposed to be submerged reefs where waves
could shoal and be ideally surfed.The prediction of surfing improvements (or impacts)is both
subjective and an emerging science;thus,is difficult to quantify.Typical wave approach directions,
typical surfzone and nearshore slopes and peel angles for desirable waves were consulted to generate
the conceptual design of the reef edges (Figure 6-5).
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GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 38
Figure 6-1. Beach Nourishment Concept
[9]’aim Beach Fill Elev,''\‘l I +13'MLLW
Figure 6-1.Beach Nourishment Concept
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GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 39
Figure 6-2. Groin Field Concept
[9]Legend
ConceptualGroinLayout
—Rock Crest
-—-Rock Toe
'3‘“.It .mun-.1.
l“M Beach Fill Elev..62};+13'MLLW
‘l .its-.Vmacmaimfin’nm-inun'.r--«4--7 a.
Figure 6-2.Groin Field Concept
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GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 40
Figure 6-3. San Luis Rey Groin Extension Concept
[9]Legend
San Luis Rey GroinModifications
—RockCrest
---ROCKT09
Figure 6-3.San Luis Rey Groin Extension Concept
GHD |Beach Sand Replenishment &Retention Device Project |June 2021 |Page 40Jan. 4, 2022 Item 4 Page 54 of 229
GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 41
Figure 6-4. Multi-Purpose Artificial Reefs Concept
[9]mm
Conceptual ArtificialReel
—RockSlope
RockCrest
7 7,Rock Toe
Toe of Slope ‘
Top (Sr Slope V
U ’4'...
|Beach Fill Elev.+13'MLLW
gm:
--'s CLEVELANDs‘r‘En_
Figure 6-4.Multi-Purpose Artificial Reefs Concept
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GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 42
Figure 6-5. Multi-Purpose Artificial Reefs Concept - Reef Detail [9]Hun-mm unm'wrmwhom!mm m:‘u m15HEhkfix'cmh''hInFPSam-
:II-vnvn-u.-'vnnimm.
Legend
ConceptualArtificialReef
—Rock Crest
—Rock Slope
-—-Ruck Toe
@33q
cow'-
mama:
(f"'—-X'-"'"-"'.-"".'X"""l‘:$
Figure 6-5.Multi-Purpose Artificial Reefs Concept -Reef Detail
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GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 43
7. Other Alternatives Considered
A number of other alternatives were considered in this study. A summary of other types of solutions
reviewed are below:
• Detached Breakwaters & T-head groins: Shore parallel, emergent crest breakwaters and T-
head groins were considered within this study. These structures can be effective methods of
shoreline stabilization; especially along beach where cross-shore sediment transport is significant.
The wave reflection from these shore-parallel structures are known to negatively impact surfing
resources. Given the importance of surfing resources to the City and stakeholders, detached
breakwaters and T-head groins were not further considered.
• Geotextile Sand Retention Structures: Temporary geotextile groins or reefs were considered,
modeled after the Upham Beach Groin Project in Florida, given their lower cost to deploy and
temporary/reversible nature. Given the water depth and wave climate of the City, the stability of
geotextile sand retention structures would likely be compromised quickly. The use of geotextiles
were rejected for this reason.
• Sand Engine: The sand engine, implemented along the Delfand Coast in the Netherlands, placed
over 20M CY of sand on a feeder beach, which allowed natural littoral dynamics to transport sand
slowly to downdrift areas of need. Sediment transport along the Delfand Coast is mostly
unidirectional, which differs from Oceanside’s bidirectional transport regime. Placement of a
similar project in the City would result in a significant amount of sand being deposited in the harbor,
likley prompting more dredging of the navigational channels.
• Oceanside Harbor Breakwater Modifications: Concepts to modify the Oceanside jetties, such
as creating a spur to the northern breakwater to act as a sand trap was considered. This feature
would need to be combined with a sand bypass system; similar to the one that was constructed
in the 1980’s. Given the historical precedent of the system at this location, this concept was not
carried forward.
• Nature-based Design Solutions & Living Shorelines: These solutions consist of use of native
materials or living systems or habitats for shoreline protection. These solutions are favored by
state agencies and stakeholders as “no-regret”, multi-benefit solutions to shoreline protection and
SLR adaptation in areas where they are appropriate. Appropriate nature-based design or living
shoreline solutions along the southern California open coast consist of use of cobble, dunes and
artificial reefs. Given the absence of a stable beach in the City, use of cobble or dunes were not
determined to be viable at this time. Should the beach stabilize as a result of implementation of
one of the alternatives presented in this study or for another reason, use of these features should
be re-considered. Reef features could be incorporated into the design of the groin or artificial reef
concepts. The highest potential for reef success would be the artificial reef because of the larger
submerged footprint.
[Q]Other Alternatives Considered
A number of other alternatives were considered in this study.A summary of other types of solutions
reviewed are below:
Detached Breakwaters &T-head groins:Shore parallel,emergent crest breakwaters and T-
head groins were considered within this study.These structures can be effective methods of
shoreline stabilization;especially along beach where cross-shore sediment transport is significant.
The wave reflection from these shore-parallel structures are known to negatively impact surfing
resources.Given the importance of surfing resources to the City and stakeholders,detached
breakwaters and T—head groins were not further considered.
Geotextile Sand Retention Structures:Temporary geotextile groins or reefs were considered,
modeled after the Upham Beach Groin Project in Florida,given their lower cost to deploy and
temporary/reversible nature.Given the water depth and wave climate of the City,the stability of
geotextile sand retention structures would likely be compromised quickly.The use of geotextiles
were rejected for this reason.
Sand Engine:The sand engine,implemented along the Delfand Coast in the Netherlands,placed
over 20M CY of sand on a feeder beach,which allowed natural littoral dynamics to transport sand
slowly to downdrift areas of need.Sediment transport along the Delfand Coast is mostly
unidirectional,which differs from Oceanside’s bidirectional transport regime.Placement of a
similar project in the City would result in a significant amount of sand being deposited in the harbor,
likley prompting more dredging of the navigational channels.
Oceanside Harbor Breakwater Modifications:Concepts to modify the Oceanside jetties,such
as creating a spur to the northern breakwater to act as a sand trap was considered.This feature
would need to be combined with a sand bypass system;similar to the one that was constructed
in the 1980’s.Given the historical precedent of the system at this location,this concept was not
carried fonNard.
Nature-based Design Solutions &Living Shorelines:These solutions consist of use of native
materials or living systems or habitats for shoreline protection.These solutions are favored by
state agencies and stakeholders as “no-regret”,multi-benefit solutions to shoreline protection and
SLR adaptation in areas where they are appropriate.Appropriate nature-based design or living
shoreline solutions along the southern California open coast consist of use of cobble,dunes and
artificial reefs.Given the absence of a stable beach in the City,use of cobble or dunes were not
determined to be viable at this time.Should the beach stabilize as a result of implementation of
one of the alternatives presented in this study or for another reason,use of these features should
be re-considered.Reef features could be incorporated into the design of the groin or artificial reef
concepts.The highest potential for reef success would be the artificial reef because of the larger
submerged footprint.
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GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 44
8. Numerical Modeling of Alternatives
Numerical model was performed to aide in the evaluation of beach nourishment and sand retention
alternatives. A primary objective of the modeling effort was to evaluate the ability of sand retention
structures to retain and prolong the performance of beach fills. The 2012 Regional Sand Beach Project
II (RSBP II) nourishments that occurred in Oceanside and Carlsbad were used to validate the model
and evaluate effectiveness of sand retention structures. Using site-specific data, the integrated
hydrodynamic, wave and sediment transport model was set up to encompass the entire Project Area
and nearshore environment. Using the coupled model, multiple configurations of groins and artificial
reefs were simulated.
Numerical modeling of shoreline morphology is inherently imprecise because of the difficultly in
mathematically describing the complicated dynamics of coastal processes and inability to forecast
future metocean conditions and their effect on nearshore littoral processes. Despite these limitations,
numerical modeling remains one of the few tools that can be applied to evaluate the feasibility of sand
retention structures and thus approximations are made for nearshore sediment dynamics based on
broad and consequential assumptions like the 1-contour line model used here. The model results
presented in this section are only one of several criteria to consider in evaluating each alternative.
8.1 Model Description
The numerical model chosen to evaluate the effectiveness of each alternative was the Littoral
Processes and Coastline Kinetics (LITPACK), part of the MIKE suite of modeling applications
developed by Delft Hydraulic Institute (DHI). LITPACK is designed to model long term shoreline
evolution for the purpose of optimizing and evaluating the design and development of coastal works.
The model couples hydrodynamic and sediment transport models to calculate littoral drift rates and
the coastline position across the model domain over the simulation period.
The model domain stretches from the southern side of the Oceanside Harbor to the Agua Hedionda
Lagoon north jetty (Figure 8-1). Wave data from CDIP Station 045 was transformed using internally in
the LITPACK model to the project shoreline. Water levels from NOAA tidal station #9410230 in La
Jolla were used. A high resolution topobathy digital elevation model (DEM) created by the Coastal
Conservancy was used for the initial model bathymetry conditions. Cross shore profiles and the initial
shoreline position were extracted from the DEM. Local sediment properties reflected sampling
analyses completed in the project area by the USACE (2018) and M&N (2016).
[Q]Numerical Modeling of Alternatives
Numerical model was performed to aide in the evaluation of beach nourishment and sand retention
alternatives.A primary objective of the modeling effort was to evaluate the ability of sand retention
structures to retain and prolong the performance of beach fills.The 2012 Regional Sand Beach Project
II (RSBP ll)nourishments that occurred in Oceanside and Carlsbad were used to validate the model
and evaluate effectiveness of sand retention structures.Using site-specific data,the integrated
hydrodynamic,wave and sediment transport model was set up to encompass the entire Project Area
and nearshore environment.Using the coupled model,multiple configurations of groins and artificial
reefs were simulated.
Numerical modeling of shoreline morphology is inherently imprecise because of the difficultly in
mathematically describing the complicated dynamics of coastal processes and inability to forecast
future metocean conditions and their effect on nearshore littoral processes.Despite these limitations,
numerical modeling remains one of the few tools that can be applied to evaluate the feasibility of sand
retention structures and thus approximations are made for nearshore sediment dynamics based on
broad and consequential assumptions like the 1-contour line model used here.The model results
presented in this section are only one of several criteria to consider in evaluating each alternative.
8.1 Model Description
The numerical model chosen to evaluate the effectiveness of each alternative was the Littoral
Processes and Coastline Kinetics (LITPACK),part of the MIKE suite of modeling applications
developed by Delft Hydraulic Institute (DHI).LlTPACK is designed to model long term shoreline
evolution for the purpose of optimizing and evaluating the design and development of coastal works.
The model couples hydrodynamic and sediment transport models to calculate littoral drift rates and
the coastline position across the model domain over the simulation period.
The model domain stretches from the southern side of the Oceanside Harbor to the Agua Hedionda
Lagoon north jetty (Figure 8-1).Wave data from CDIP Station 045 was transformed using internally in
the LlTPACK model to the project shoreline.Water levels from NOAA tidal station #9410230 in La
Jolla were used.A high resolution topobathy digital elevation model (DEM)created by the Coastal
Conservancy was used for the initial model bathymetry conditions.Cross shore profiles and the initial
shoreline position were extracted from the DEM.Local sediment properties reflected sampling
analyses completed in the project area by the USACE (2018)and M&N (2016).
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GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 45
Figure 8-1. Numerical Modeling Domain
I](12 04 I16 0.8—:—:IWasMapFlam:LalIertCuliu-Imlcm:HwinnalDitm:mm lensGui:MDlawman-av:mmFeel
Legend
Approximate ModelBoundary
10'Contour(NAVDBB)
Figure 8-1.Numerical Modeling Domain
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GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 46
8.2 Calibration and Validation
Model calibration and validation are important to evaluate the model’s ability to simulate observed
shoreline changes. Littoral sediment transport rates were calibrated to fall within the range of values
estimated by previous studies. Previous studies agree the net direction of sediment transport is south,
but the estimated net transport rate varies in each study within a range of 100,000 to 250,000 cy/year.
Most of these studies are evaluating transport at a regional scale and therefore do not attempt to
distinguish sediment transport patterns within the study area. The large range and uncertainty
associated with measured and estimated littoral sediment transport rates necessitated an iterative
approach to calibrating the model.
The LITPACK model was validated against the observed shoreline changes after the 2012 Regional
Sand Beach Project II (RSBP II) in which 293,000 cy were placed at Oceanside and 218,000 cy placed
at North Carlsbad. The model predicted dispersion of the beach fills throughout Oceanside to North
Carlsbad reach with increased beach widths of 50 feet on average three years after the initial
placement. In comparison to the observed shoreline changes, the model overpredicted the beach
width gained from the RBSP II project along south Oceanside (i.e. beach fill eroded faster than
anticipated) and under predicted the accretion that was observed throughout Carlsbad.
A description of the uncertainties and model limitations is described in Appendix B. Some of the key
factors influencing the ability of the model to reproduce measured shoreline changes are the
uncertainties in local littoral transport rates and the inability to resolve the complicated dynamics of
the harbor structures and their effect on littoral transport rates.
The LITPACK model was able to reproduce general trends of shoreline change in the vicinity of the
RBSP II placement areas but was unable to accurately reproduce measured shoreline changes at
specific locations. Therefore, this model can be useful for estimating the general shoreline change
trends from a variety of sand retention configurations but cannot be relied upon to predict shoreline
change at a specific time and location.
8.3 LITPACK Sand Retention Device Modeling
Multiple configurations of a groin field and series of artificial reefs were evaluated for comparison to a
“Nourishment Only Scenario” (NOS). The NOS functions as an assessment of the efficacy of a sand
replenishment project similar to what was placed for the RSBP II project. The sand retention
alternatives were evaluated at “full-scale” and “pilot-scale” as described below. The full-scale model
results were used for direct comparison of sand retention performance to NOS for the entire project
reach. The pilot-scale results are intended for use in evaluating the performance of a smaller sand
retention project recognizing the need to monitor and measure performance at a smaller scale before
implementing a full-scale solution.
8.3.1 Full-scale Model Results
The full-scale retention configurations included structures from Tyson Street at the north end to Buena
Vista lagoon at the south end. The modeled sand retention devices were simulated using the same
input data and parameters as the NOS. The sand retention devices were modeled with the same
volume of sand as RBSP II, but the placement locations were adjusted to distribute fill throughout the [$18.2 Calibration and Validation
Model calibration and validation are important to evaluate the model’s ability to simulate observed
shoreline changes.Littoral sediment transport rates were calibrated to fall within the range of values
estimated by previous studies.Previous studies agree the net direction of sediment transport is south,
but the estimated net transport rate varies in each study within a range of 100,000 to 250,000 cy/year.
Most of these studies are evaluating transport at a regional scale and therefore do not attempt to
distinguish sediment transport patterns within the study area.The large range and uncertainty
associated with measured and estimated littoral sediment transport rates necessitated an iterative
approach to calibrating the model.
The LITPACK model was validated against the observed shoreline changes after the 2012 Regional
Sand Beach Project II (RSBP II)in which 293,000 cy were placed at Oceanside and 218,000 cy placed
at North Carlsbad.The model predicted dispersion of the beach fills throughout Oceanside to North
Carlsbad reach with increased beach widths of 50 feet on average three years after the initial
placement.In comparison to the observed shoreline changes,the model overpredicted the beach
width gained from the RBSP II project along south Oceanside (i.e.beach fill eroded faster than
anticipated)and under predicted the accretion that was observed throughout Carlsbad.
A description of the uncertainties and model limitations is described in Appendix B.Some of the key
factors influencing the ability of the model to reproduce measured shoreline changes are the
uncertainties in local littoral transport rates and the inability to resolve the complicated dynamics of
the harbor structures and their effect on littoral transport rates.
The LITPACK model was able to reproduce general trends of shoreline change in the vicinity of the
RBSP ||placement areas but was unable to accurately reproduce measured shoreline changes at
specific locations.Therefore,this model can be useful for estimating the general shoreline change
trends from a variety of sand retention configurations but cannot be relied upon to predict shoreline
change at a specific time and location.
8.3 LITPACK Sand Retention Device Modeling
Multiple configurations of a groin field and series of artificial reefs were evaluated for comparison to a
“Nourishment Only Scenario”(N08).The NOS functions as an assessment of the efficacy of a sand
replenishment project similar to what was placed for the RSBP II project.The sand retention
alternatives were evaluated at “full-scale”and “pilot-scale”as described below.The full-scale model
results were used for direct comparison of sand retention performance to NOS for the entire project
reach.The pilot-scale results are intended for use in evaluating the performance of a smaller sand
retention project recognizing the need to monitor and measure performance at a smaller scale before
implementing a full-scale solution.
8.3.1 Full-scale Model Results
The full-scale retention configurations included structures from Tyson Street at the north end to Buena
Vista lagoon at the south end.The modeled sand retention devices were simulated using the same
input data and parameters as the NOS.The sand retention devices were modeled with the same
volume of sand as RBSP II,but the placement locations were adjusted to distribute fill throughout the
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GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 47
retention structures and downdrift areas. Some of the key features of the layout of these structures
includes:
• Groin field layout (length and spacing) was informed by the extensive physical modeling performed
as part of the 1980 U.S. Army Corp of Engineers (USACE) study, Design of Structures for Harbor
Improvement and Beach Erosion Control which evaluated ten different groin field layouts. The
groin field layout assumes 600-foot long groins spaced at 1,000 feet alongshore. The two
southernmost groins were tapered to 400 feet and 300 feet long respectively to reduce downdrift
impacts based on findings from the USACE’s physical modeling study (1980).
• The artificial reefs are modeled as emergent breakwaters in the LITPACK model. The spacing and
configuration of these reefs were based on guidance from the Coastal Engineering Manual (CEM)
as well as some of the results from the USACE’s physical modeling study (1980). For modeling
purposes the artificial reefs were assumed to have 600-foot-long crests, spaced at 1,200 feet
alongshore and placed 1,000 feet offshore.
The model predicted retention of sand throughout the groin field with accretion of sand in fillets on
both sides of each groin. Although spread over a larger area, the nourishment prefill stayed in the
system and was well retained by the groins. When compared to the accumulated volume of the NOS,
the full groin layout retained 175% more sand within the fill placement area based on the 2015
predicted shoreline position. Model results of the artificial reef configuration showed the formation of
salient in the lee of the artificial breakwaters, with slight erosional effects between the structures. The
artificial reefs performed similar to groins, retaining 185% more sand than the NOS within the fill
placement area. A comparison of the model results from the 2015 simulation year are provided in
Figure 8-2, illustrating the different shoreline planforms predicted for each alternative. [Q]retention structures and downdrift areas.Some of the key features of the layout of these structures
includes:
Groin field layout (length and spacing)was informed by the extensive physical modeling performed
as part of the 1980 US.Army Corp of Engineers (USACE)study,Design of Structures for Harbor
Improvement and Beach Erosion Control which evaluated ten different groin field layouts.The
groin field layout assumes 600—foot long groins spaced at 1,000 feet alongshore.The two
southernmost groins were tapered to 400 feet and 300 feet long respectively to reduce downdrift
impacts based on findings from the USACE’s physical modeling study (1980).
The artificial reefs are modeled as emergent breakwaters in the LITPACK model.The spacing and
configuration of these reefs were based on guidance from the Coastal Engineering Manual (CEM)
as well as some of the results from the USACE’s physical modeling study (1980).For modeling
purposes the artificial reefs were assumed to have 600-foot-long crests,spaced at 1,200 feet
alongshore and placed 1,000 feet offshore.
The model predicted retention of sand throughout the groin field with accretion of sand in fillets on
both sides of each groin.Although spread over a larger area,the nourishment prefill stayed in the
system and was well retained by the groins.When compared to the accumulated volume of the NOS,
the full groin layout retained 175%more sand within the fill placement area based on the 2015
predicted shoreline position.Model results of the artificial reef configuration showed the formation of
salient in the lee of the artificial breakwaters,with slight erosional effects between the structures.The
artificial reefs performed similar to groins,retaining 185%more sand than the NOS within the fill
placement area.A comparison of the model results from the 2015 simulation year are provided in
Figure 8-2,illustrating the different shoreline planforms predicted for each alternative.
GHD |Beach Sand Replenishment &Retention Device Project |June 2021 |Page 47Jan. 4, 2022 Item 4 Page 61 of 229
GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 48
Figure 8-2. Full-scale model results (simulated 2015 shoreline position)
Legend
Modeled Groins Shoreline Position #2015
—Groin Crest
.’gf’ié’fiul‘yfiéis .
~..
._rmise'aa_s ''.'_'4n“?‘
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Leonid
ModeledArt.Reef Sh oreline Position 112015
—Artificial ReefCrest
'Jspuawas“;"tn :é'héaipallsv.{militants _ii '_I -»:(fiy -'....@~-'.--i,''ISWWIFBJA S"
Legend
Modeled NOS Shoreline Position “2015
"Nutmeg-Jug»
fl I'M 02
—=—=It:
IIIm:muflnammun-Inna:main“me:illIlla:manuals:
Figure 8-2.Full-scale model results (simulated 2015 shoreline position)
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GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 49
8.3.2 Pilot-scale Results - Groin Field
The full groin and artificial reef layouts stretching from Tyson Street to Buena Vista Lagoon were
narrowed down to pilot projects and modeled separately. The groin field pilot was laid out with the
goal of demonstrating an effective sand retention project that could be expanded over time.
A series of four groins were modeled to capture the effects in three compartments. The length and
spacing of the groins were the same as the full groin layout, since the structures would remain, if
successful, and could be expanded to the full groin field layout discussed above. The pilot groins and
downdrift area were prefilled with the same 293,000 cy placement volume as the Oceanside fill in
RSBP II. The prefill was distributed evenly from Tyson Street at the northernmost groin to Forster
Street just downdrift of the southernmost groin. Of the total prefill amount, the 3,000-foot-long groin
prefill area received 235,000 cy of prefill and the 750 feet of downdrift area received 58,000 cy of prefill
within the model. The results are shown below in Figure 8-3.
Like the modeling of the full groin layout, the model predicts uniform retention of sediment throughout
the groin field. The initial fill volume was largely retained within the pilot groin system with accretion of
sand in fillets upcoast of each groin. Downdrift erosion was predicted to extend roughly a half mile
south of the groin field indicating the importance of a monitoring and management plan to mitigate
these potential impacts.
The model results indicate the pilot configuration would retain a much larger beach area within the
initial placement zone in comparison to a Nourishment Only Scenario (i.e. RBSP II). The beach width
gained from RBSP II in the original placement area was about 50 feet when averaged over the three-
year period following initial placement. The model results suggest 100-150 feet of beach width gains
when averaged over the model simulation.
While the model results for sand retention are promising, the model limitations must be acknowledged
including the inability to simulate the Oceanside Harbor structures and their influence on sediment
supply to the study reach. The groins are also simulated as impervious structures which may result in
more retention than would occur if these are semi-pervious structures comprised of large armor stone.
These model limitations likely result in an overestimate of the beach width retained within the pilot
system. Additional analysis of the groin field pilot would involve sensitivity analyses on the placement
of initial fill and subsequent fill in the vicinity of the groin field along with variations in groin length and
spacing. [Q]8.3.2 Pilot-scale Results -Groin Field
The full groin and artificial reef layouts stretching from Tyson Street to Buena Vista Lagoon were
narrowed down to pilot projects and modeled separately.The groin field pilot was laid out with the
goal of demonstrating an effective sand retention project that could be expanded over time.
A series of four groins were modeled to capture the effects in three compartments.The length and
spacing of the groins were the same as the full groin layout,since the structures would remain,if
successful,and could be expanded to the full groin field layout discussed above.The pilot groins and
downdrift area were prefilled with the same 293,000 cy placement volume as the Oceanside fill in
RSBP II.The prefill was distributed evenly from Tyson Street at the northernmost groin to Forster
Street just downdrift of the southernmost groin.Of the total prefill amount,the 3,000-foot—long groin
prefill area received 235,000 cy of prefill and the 750 feet of downdrift area received 58,000 cy of prefill
within the model.The results are shown below in Figure 8-3.
Like the modeling of the full groin layout,the model predicts uniform retention of sediment throughout
the groin field.The initial fill volume was largely retained within the pilot groin system with accretion of
sand in fillets upcoast of each groin.Downdrift erosion was predicted to extend roughly a half mile
south of the groin field indicating the importance of a monitoring and management plan to mitigate
these potential impacts.
The model results indicate the pilot configuration would retain a much larger beach area within the
initial placement zone in comparison to a Nourishment Only Scenario (i.e.RBSP II).The beach width
gained from RBSP II in the original placement area was about 50 feet when averaged over the three-
year period following initial placement.The model results suggest 100-150 feet of beach width gains
when averaged over the model simulation.
While the model results for sand retention are promising,the model limitations must be acknowledged
including the inability to simulate the Oceanside Harbor structures and their influence on sediment
supply to the study reach.The groins are also simulated as impervious structures which may result in
more retention than would occur ifthese are semi-pervious structures comprised of large armor stone.
These model limitations likely result in an overestimate of the beach width retained within the pilot
system.Additional analysis of the groin field pilot would involve sensitivity analyses on the placement
of initial fill and subsequent fill in the vicinity of the groin field along with variations in groin length and
spacmg.
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GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 50
Figure 8-3. Modeled Shoreline Change for Groin Pilot[9]Modeled Shoreline Change:Groin Pilot
Modeled Groin Pilot Shoreline Position 1f2015
—Groin PilotCrest
500 I
40”'—F'ilul;Modeled Pilot Groin 1:213:13.
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Figure 8-3.Modeled Shoreline Change for Groin Pilot
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8.3.3 Pilot-scale Results - Artificial Reef
The artificial reef pilot project consisted of the northern two artificial reefs, spaced and sized the same
as the full layout. A downdrift/prefill of the same amount and placement as the groin pilot was included
in the LITPACK model (i.e. 293,000 cy placed from Tyson Street to Forster St. at the beginning of the
model simulation). Of the total prefill amount, the 3,000-foot-long groin prefill area received 235,000
cy of prefill and the 750 feet of downdrift area received 58,000 cy of prefill within the model. The results
are shown below in Figure 8-4.
The model predicted large salient formation in the lee of each reef structure, with retention benefits
extending upcoast well beyond the influence of the offshore structures. More downdrift erosion was
predicted for the pilot-scale configuration than the full-scale configuration, extending about a half mile
downdrift of the structures. The amount of beach area retained throughout the model simulation was
comparable to the Groin Field Pilot results, except the planform distribution of sand would be different.
Although the model predicted beach widths are quite large, these are subject to similar model
limitations which may be contributing to an overestimate of the potential retention benefits.
Since these offshore reef structures have not been widely implemented in the Southern California
region there are limited real world observations of how this system would function. Additional analysis
of the Artificial Reef Pilot may involve two-dimensional modeling to simulate the complicated
hydrodynamics that may result from these structures. This would provide another tool for estimating
their ability to retain a sandy beach and the interaction between two or more artificial reef structures
placed in series along the pilot study area. [Q]8.3.3 Pilot-scale Results -Artificial Reef
The artificial reef pilot project consisted of the northern two artificial reefs,spaced and sized the same
as the full layout.A downdrift/prefill of the same amount and placement as the groin pilot was included
in the LITPACK model (i.e.293,000 cy placed from Tyson Street to Forster St.at the beginning of the
model simulation).Of the total prefill amount,the 3,000-foot-long groin prefill area received 235,000
cy of prefill and the 750 feet of downdrift area received 58,000 cy of prefill within the model.The results
are shown below in Figure 8-4.
The model predicted large salient formation in the lee of each reef structure,with retention benefits
extending upcoast well beyond the influence of the offshore structures.More downdrift erosion was
predicted for the pilot-scale configuration than the full-scale configuration,extending about a half mile
downdrift of the structures.The amount of beach area retained throughout the model simulation was
comparable to the Groin Field Pilot results,except the planform distribution of sand would be different.
Although the model predicted beach widths are quite large,these are subject to similar model
limitations which may be contributing to an overestimate of the potential retention benefits.
Since these offshore reef structures have not been widely implemented in the Southern California
region there are limited real world observations of how this system would function.Additional analysis
of the Artificial Reef Pilot may involve two-dimensional modeling to simulate the complicated
hydrodynamics that may result from these structures.This would provide another tool for estimating
their ability to retain a sandy beach and the interaction between two or more artificial reef structures
placed in series along the pilot study area.
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Figure 8-4. Modeled Shoreline Change for Reef Pilot[9]Modeled Shoreline Change:Art.Reef Pilot
400 -
—Modeled PilotArt.Reef LaWut1.9013
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—Modeled Pilot Art.Reef Layout 112015
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Reach E Reach D Reach (3 Reach B Reach A
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Legend
—Pilot Artificial Reef Crest
Modeled Art.Reef Shoreline Position 112015
0
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Figure 8-4.Modeled Shoreline Change for Reef Pilot
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9. Multi-Criteria Analysis
A multi-criteria analysis (MCA) was performed to compare alternatives based on a wide range of
criteria that reflects the diversity of opinions and input received from the public engagement activities.
Rather than rely solely on economics, or a benefit-cost ratio (largely influenced by economics), the
multi-criteria analysis is based on customized criteria developed to align with project objectives and
public feedback.
9.1 Alternative Analysis Criteria
The Oceanside Preliminary Engineering Evaluation and Feasibility Study aims to develop a multi-
benefit project that is environmentally sensitive, technically and financially feasible, with a reasonable
chance of securing permits. To meet these objectives, the final design of any of the alternatives will
start with a pilot project that is adaptable and reversible, and informed by a scientific monitoring
program that is led by Scripps Institution of Oceanography.
Public and stakeholder feedback was essential to the development and weighting of the alternative
analysis criteria. Results from the polling conducted during a public outreach meeting on September
15th, 2021 indicated that downdrift erosion, sea level rise resiliency, and surfing related impacts were
of the highest concern. These results were reflected in the poll question results shown in Table 9-1.
Table 9-1 Public Outreach – Poll Question Result
Poll Question 6 Impacts of concern Voting Results
What project impacts
are you most concerned about? (Select up to three)
Downdrift erosion 48% (31/65)
Sea Level Rise Resilience 46% (30/65)
Surfing related impacts 29% (19/65)
The criteria developed for this analysis have been organized into three categories of Technical
Performance, Financial and Environmental. These categories reflect the general project objectives
and public feedback gathered in the public workshops and stakeholder meetings. The specific criteria
within each category are discussed in the following sections along with the basis for evaluating each
criterion.
9.1.1 Technical Performance
South of the Oceanside Pier, beaches have been limited in width to non-existent in recent years
severely limiting safe public access and recreation along this stretch of shoreline. Technical
performance criteria relate to the ability of each alternative to restore and retain a sandy beach with a
focus on public safety, sediment transport effects on down drift beaches, and resilience to sea level
rise. Coastal resilience and the vulnerability of resources and development along the City due to the
loss of beach area was a common public concern expressed during the public workshop and
stakeholder meetings. The specific criteria for this category are listed in Table 9-2 along with a
description about how alternatives will be evaluated for each criterion. [Q]Multi-Criteria Analysis
A multi-criteria analysis (MCA)was performed to compare alternatives based on a wide range of
criteria that reflects the diversity of opinions and input received from the public engagement activities.
Rather than rely solely on economics,or a benefit-cost ratio (largely influenced by economics),the
multi-criteria analysis is based on customized criteria developed to align with project objectives and
public feedback.
9.1 Alternative Analysis Criteria
The Oceanside Preliminary Engineering Evaluation and Feasibility Study aims to develop a multi-
benefit project that is environmentally sensitive,technically and financially feasible,with a reasonable
chance of securing permits.To meet these objectives,the final design of any of the alternatives will
start with a pilot project that is adaptable and reversible,and informed by a scientific monitoring
program that is led by Scripps Institution of Oceanography.
Public and stakeholder feedback was essential to the development and weighting of the alternative
analysis criteria.Results from the polling conducted during a public outreach meeting on September
15th,2021 indicated that downdrift erosion,sea level rise resiliency,and surfing related impacts were
of the highest concern.These results were reflected in the poll question results shown in Table 9-1.
Table 9-1 Public Outreach —Poll Question Result
Poll Question 6 Impacts of concern Voting Results
What project impacts Downdrift erosion 48%(31/65)
are you most Sea Level Riseconcernedabout?Resilience 46%(30/65)
(Select up to three)Surfing related.29%(19/65)Impacts
The criteria developed for this analysis have been organized into three categories of Technical
Performance,Financial and Environmental.These categories reflect the general project objectives
and public feedback gathered in the public workshops and stakeholder meetings.The specific criteria
within each category are discussed in the following sections along with the basis for evaluating each
criterion.
9.1.1 Technical Performance
South of the Oceanside Pier,beaches have been limited in width to non-existent in recent years
severely limiting safe public access and recreation along this stretch of shoreline.Technical
performance criteria relate to the ability of each alternative to restore and retain a sandy beach with a
focus on public safety,sediment transport effects on down drift beaches,and resilience to sea level
rise.Coastal resilience and the vulnerability of resources and development along the City due to the
loss of beach area was a common public concern expressed during the public workshop and
stakeholder meetings.The specific criteria for this category are listed in Table 9-2 along with a
description about how alternatives will be evaluated for each criterion.
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Table 9-2 Technical Performance Criteria
Criteria Basis of Evaluation
Creation/Restoration of Beach Overall performance of the system, pertaining to the long-term creation/restoration of a dry sand beach.
Down-Drift Impacts Ability to maintain longshore sediment transport to downdrift beaches.
Public Safety Ability to preserve safety of beach and ocean recreation through improved lifeguard access.
Sea Level Rise Adaptability
Ability to adapt to future SLR scenarios of up to 2 feet while continuing to meet project objectives. How difficult would it be to augment or modify each alternative to accommodate a 2-foot SLR scenario?
9.1.2 Financial
The financial category includes criteria that account for the approximate lifecycle costs of each design
alternative along with a qualitative assessment of the in-direct economic benefits from the alternatives.
The lifecycle costs are opinions of costs based on conceptual design drawings and are only intended
to provide a rough order-of-magnitude estimate of potential Project costs for the sole purpose of
comparing alternatives to one another. These opinions of cost do not reflect the actual cost of the
Project and will be subject to refinement upon selection and optimization of a preferred alternative.
Lifecycle costs include estimated costs associated with initial costs, operations & maintenance, and
adaptation at the end of the pilot phase. Financial criteria and their basis of evaluation are listed in
Table 9-3.
Table 9-3 Financial Criteria
Criteria Basis of Evaluation
Lifecycle Costs:
Initial Costs
Estimated capital cost of the initial Project including soft costs
associated with permitting, engineering design and construction management
Operation & Maintenance Estimated costs of operational and maintenance efforts over the 50-year design life (e.g. beach re-nourishment, or maintenance & repair of retention structures).
Adaptation Estimated costs associated with adapting retention structures to improve performance at the end of the pilot project phase.
Economic Benefits:
In-direct economic benefits Based on a qualitative assessment of increased economic activity generated by a stable and sustainable dry beach area available for beach and ocean recreation.
9.1.3 Environmental
Environmental criteria were developed to evaluate the project’s ability to preserve or enhance coastal
resources in the project vicinity. The criteria include considerations for marine biological resources,
surfing resources, aesthetics, beach recreation and coastal access. The preservation and [Q]Table 9-2 Technical Performance Criteria
Creation/Restoration of Overall performance of the system,pertaining to the long-term
Beach creation/restoration of a dry sand beach.
Ability to maintain longshore sediment transport to downdriftDown-Drlft Impacts beaches.
Ability to preserve safety of beach and ocean recreation through
improved lifeguard access.
Ability to adapt to future SLR scenarios of up to 2 feet while
continuing to meet project objectives.How difficult would it be to
augment or modify each alternative to accommodate a 2-foot SLR
scenafio?
Public Safety
Sea Level Rise Adaptability
9.1 .2 Financial
The financial category includes criteria that account for the approximate lifecycle costs of each design
alternative along with a qualitative assessment of the in-direct economic benefits from the alternatives.
The lifecycle costs are opinions of costs based on conceptual design drawings and are only intended
to provide a rough order-of—magnitude estimate of potential Project costs for the sole purpose of
comparing alternatives to one another.These opinions of cost do not reflect the actual cost of the
Project and will be subject to refinement upon selection and optimization of a preferred alternative.
Lifecycle costs include estimated costs associated with initial costs,operations &maintenance,and
adaptation at the end of the pilot phase.Financial criteria and their basis of evaluation are listed in
Table 9—3.
Table 9-3 Financial Criteria
Lifecycle Costs:
Estimated capital cost of the initial Project including soft costs
Initial Costs associated with permitting,engineering design and construction
management
Estimated costs of operational and maintenance efforts over the 50-
Operation &Maintenance year design life (e.g.beach re-nourishment,or maintenance &repair
of retention structures).
Estimated costs associated with adapting retention structures to
Adaptation improve performance at the end of the pilot project phase.
Economic Benefits:
Based on a qualitative assessment of increased economic activity
ln-direct economic benefits generated by a stable and sustainable dry beach area available for
beach and ocean recreation.
9.1 .3 Environmental
Environmental criteria were developed to evaluate the project’s ability to preserve or enhance coastal
resources in the project vicinity.The criteria include considerations for marine biological resources,
surfing resources,aesthetics,beach recreation and coastal access.The preservation and
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enhancement of these resources is an objective of the project and will be key focus areas during the
environmental analysis, regulatory review and permitting process. The specific criteria and their basis
of evaluation are listed in Table 9-4.
Table 9-4. Environmental Criteria
Criteria Basis of Evaluation
Biological Resources
Ability to preserve and/or enhance marine biological resources in inter-tidal and nearshore waters. Alternatives which provide a stable beach will offer more sustainable inter-tidal habitat. Sand retention structures are assumed to have a temporary impact on sand bottom habitat, but also creation of new rocky inter-tidal habitat.
Surfing Resources Ability to preserve or enhance existing surfing resources.
Aesthetics Ability to preserve coastal aesthetics throughout Oceanside. Aesthetics are subjective but the analysis assumes a positive aesthetic is associated with the presence of a sandy beach.
Beach Recreation Ability to preserve and/or enhance beach recreation area (i.e. towel space), particularly in areas most accessible like the Pier and South Strand reaches.
Coastal Access Ability to enhance lateral beach access through the creation of stable, dry beach areas.
9.2 Weighting and Scoring System
The MCA scoring and weighting presented in this report reflects input from the multi-disciplinary
Project team including thoughts and opinions from a diverse group of team members with technical,
financial and environmental expertise in effort to reduce individual bias and subjectivity from
influencing the results.
The maximum potential score for each alternative is a function of how well the alternative satisfies the
criteria within three general categories of Technical Performance, Financial and Environmental. The
results presented in this report are based on a weighting of 40/20/40
(Technical/Financial/Environmental) breakdown among these categories as shown in Table 9-5. In
other words, the Technical Performance and Environmental categories have a maximum score of
40%, and Financial criteria account for up to 20% of the total score. Technical Performance and
Environmental categories were weighted slightly higher because the criteria in this category closely
align with the primary objectives and feedback received from the public workshop and stakeholder
meetings. The sensitivity of these weightings on the results were evaluated and discussed in Section
9.4.
Table 9-5. MCA Category Weighing
Category Weight
Technical 40%
Financial 20%
Environmental 40%
Total 100% [Q]enhancement of these resources is an objective of the project and will be key focus areas during the
environmental analysis,regulatory review and permitting process.The specific criteria and their basis
of evaluation are listed in Table 9-4.
Table 9-4.Environmental Criteria
Ability to preserve and/or enhance marine biological resources in
inter-tidal and nearshore waters.Alternatives which provide a stable
Biological Resources beach will offer more sustainable inter-tidal habitat.Sand retention
structures are assumed to have a temporary impact on sand bottom
habitat,but also creation of new rocky inter-tidal habitat.
Surfing Resources Ability to preserve or enhance existing surfing resources.
Ability to preserve coastal aesthetics throughout Oceanside.
Aesthetics Aesthetics are subjective but the analysis assumes a positive
aesthetic is associated with the presence of a sandy beach.
Ability to preserve and/or enhance beach recreation area (i.e.towel
Beach Recreation space),particularly in areas most accessible like the Pier and South
Strand reaches.
Ability to enhance lateral beach access through the creation of
Coastal Access stable,dry beach areas.
9.2 Weighting and Scoring System
The MCA scoring and weighting presented in this report reflects input from the multi-disciplinary
Project team including thoughts and opinions from a diverse group of team members with technical,
financial and environmental expertise in effort to reduce individual bias and subjectivity from
influencing the results.
The maximum potential score for each alternative is a function of how well the alternative satisfies the
criteria within three general categories of Technical Performance,Financial and Environmental.The
results presented in this report are based on a weighting of 40/20/40
(Technical/Financial/Environmental)breakdown among these categories as shown in Table 9-5.In
other words,the Technical Performance and Environmental categories have a maximum score of
40%,and Financial criteria account for up to 20%of the total score.Technical Performance and
Environmental categories were weighted slightly higher because the criteria in this category closely
align with the primary objectives and feedback received from the public workshop and stakeholder
meetings.The sensitivity of these weightings on the results were evaluated and discussed in Section
9.4.
Table 9-5.MCA Category Weighing
Technical 40%
Financial 20%
Environmental 40%
Total 100%
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The individual criterion within each category were also assigned a weighting to determine what
percentage of the available score should be allocated to each. The criteria weightings are shown in
the left column of Table 9-6 and make up 100% of the available score within each category. In most
cases the criteria were equally weighted within the Technical Performance and Environmental
categories, which reflected the feedback from the Project team that no single criterion was significantly
more important than others.
The Financial criteria was weighted 70% for lifecycle costs and 30% for in-direct economic benefits
resulting from a restored dry beach in the most accessible coastal areas of Oceanside (Pier and South
Strand). Lifecycle cost is the estimated actual monetary cost of the project including costs for initial
capital investment, operations & maintenance and adaptation/structure modification at the end of the
pilot phase, which were calculated for each alternative (i.e. quantitative). The Lifecycle cost score was
calculated by applying a graduated scoring system in which the difference between highest and lowest
cost alternatives was divided into five equal increments. The highest possible score (5) was assigned
to alternatives with a lifecycle cost within the lowest increment. The lowest possible score was
assigned to alternatives with a lifecycle cost within the highest increment.
Scoring of individual criteria was based on a scale of 1 to 5 for each alternative. A high score indicates
an alternative has a good chance of satisfying the objectives of each criterion. A low score indicates
an alternative has a poor chance of satisfying the objectives of each criterion. For some criteria (e.g.
beach restoration, Iifecycle costs) numerical modeling results and calculations were available to
support the scoring of each alternative. For other criteria, where metrics were unavailable to facilitate
comparison, the scoring was based on the outcome of discussion and debate among project team
members.
Individual scores were multiplied by the criterion weighting and category weighting to arrive at a
weighted score for each alternative and criterion. For example, if an alternative received a high score
(e.g. 4 out of 5), it would be multiplied by the criteria weighting (e.g. 20%) and the category weighing
(e.g. 40%) for a weighted score of 6.4% (i.e. 4/5 x 0.20 x 0.40 = 0.064). The weighted scores were
then summed for each alternative and category to form a total score. Note, the weighted and total
scores have been rounded to the nearest whole percentage in the results table.
9.3 Results
The results of the MCA indicated the highest ranked alternative was Groins, followed by Multi-purpose
Reefs. These top two alternatives were separated by 8% from one another in total score which was
meaningful when considering the sensitivity of the scoring and weighting system (discussed in Section
9.4). Beach Nourishment ranked third, about 17% lower than the Groins and 9% lower than Multi-
purpose Reefs. The No Project alternative ranked last with very low scores in the Technical
Performance and Environmental categories. A detailed summary of the MCA is provided in Table 9-6.
A summary of the rationale used to assign scores and differentiate among alternatives is provided in
the following sections. Please refer to Appendix C for the detailed scoring matrix which includes the
numeric score, weighted score, and comments for each criterion. [Q]The individual criterion within each category were also assigned a weighting to determine what
percentage of the available score should be allocated to each.The criteria weightings are shown in
the left column of Table 9—6 and make up 100%of the available score within each category.In most
cases the criteria were equally weighted within the Technical Performance and Environmental
categories,which reflected the feedback from the Project team that no single criterion was significantly
more important than others.
The Financial criteria was weighted 70%for lifecycle costs and 30%for in-direct economic benefits
resulting from a restored dry beach in the most accessible coastal areas of Oceanside (Pier and South
Strand).Lifecycle cost is the estimated actual monetary cost of the project including costs for initial
capital investment,operations &maintenance and adaptation/structure modification at the end of the
pilot phase,which were calculated for each alternative (i.e.quantitative).The Lifecycle cost score was
calculated by applying a graduated scoring system in which the difference between highest and lowest
cost alternatives was divided into five equal increments.The highest possible score (5)was assigned
to alternatives with a lifecycle cost within the lowest increment.The lowest possible score was
assigned to alternatives with a lifecycle cost within the highest increment.
Scoring of individual criteria was based on a scale of 1 to 5 for each alternative.A high score indicates
an alternative has a good chance of satisfying the objectives of each criterion.A low score indicates
an alternative has a poor chance of satisfying the objectives of each criterion.For some criteria (e.g.
beach restoration,lifecycle costs)numerical modeling results and calculations were available to
support the scoring of each alternative.For other criteria,where metrics were unavailable to facilitate
comparison,the scoring was based on the outcome of discussion and debate among project team
members.
Individual scores were multiplied by the criterion weighting and category weighting to arrive at a
weighted score for each alternative and criterion.For example,if an alternative received a high score
(e.g.4 out of 5),it would be multiplied by the criteria weighting (e.g.20%)and the category weighing
(e.g.40%)for a weighted score of 6.4%(i.e.4/5 X 0.20 x 0.40 =0.064).The weighted scores were
then summed for each alternative and category to form a total score.Note,the weighted and total
scores have been rounded to the nearest whole percentage in the results table.
9.3 Results
The results of the MCA indicated the highest ranked alternative was Groins,followed by Multi-purpose
Reefs.These top two alternatives were separated by 8%from one another in total score which was
meaningful when considering the sensitivity of the scoring and weighting system (discussed in Section
9.4).Beach Nourishment ranked third,about 17%lower than the Groins and 9%lower than Multi-
purpose Reefs.The No Project alternative ranked last with very low scores in the Technical
Performance and Environmental categories.A detailed summary of the MCA is provided in Table 9-6.
A summary of the rationale used to assign scores and differentiate among alternatives is provided in
the following sections.Please refer to Appendix C for the detailed scoring matrix which includes the
numeric score,weighted score,and comments for each criterion.
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Table 9-6. Multi Criteria Decision Matrix
Weight Criteria
No Project
Alternative 1 Alternative 2 Alternative 3 Alternative 4
Beach Nourishment
Program Groins
San Luis Rey Groin Extension
& Beach Nour.
Multi-Purpose
Artificial Reefs
Weighted Score Weighted Score Weighted Score Weighted Score Weighted Score
40% TECHNICAL PERFORMANCE
25% Creation/Restoration of Beach 2% 4% 10% 4% 8%
25% Down Drift Impacts 2% 10% 6% 10% 6%
25% Public Safety 2% 6% 6% 6% 6%
25% Sea Level Rise Adaptability 2% 4% 8% 4% 10%
SUBTOTAL out of 40% 8% 24% 30% 24% 30%
20% FINANCIAL
70% Life-cycle Costs 14% 14% 11% 11% 3%
30% In-direct economic benefits 1% 2% 6% 2% 5%
SUBTOTAL out of 20% 15% 16% 17% 14% 8%
40% ENVIRONMENTAL
20% Biological Resources 2% 5% 6% 5% 8%
20% Surfing Resources 2% 5% 6% 5% 6%
20% Aesthetics 3% 5% 6% 5% 6%
20% Beach Recreation 2% 5% 6% 5% 6%
20% Coastal Access 2% 5% 8% 5% 8%
SUBTOTAL out of 40% 10% 24% 34% 24% 35%
Total Score (out of 100%) 33% 64% 81% 62% 73%
Ranking 5 3 1 2 4
1. Lifecycle costs include estimated costs associated with capital, operation & maintenance and estimated adaptation cost at the end of the pilot phase. [9]Table 9-6.Multi Criteria Decision Matrix
Alternative 1 Alternative 2 Alternative 3 Alternative 4
No Prolect
Beach San Luis Rey
Nourishment Groin Extension Multi-Purpose
Program &Beach Nour.Artificial Reefs
Criteria
40%TECHNICAL PERFORMANCE A
25%Creation/Restoration of Beach 2%4%10%4%8%
25%Down Drift Impacts 2%10%6%10%6%
25%Public Safety 2%6%6%6%6%
25%Sea Level Rise Adaptability 2%4%8%4%10%
SUBTOTAL out of 40%8%24%30%24%30%-‘FINANCIAL
70%Life-cycle Costs 14%14%1 1%1 1%3%
30%ln-direct economic benefits 1%2%6%2%5%
SUBTOTAL out of 20%15%16%17%14%8%
ENVIRONMENTAL
20%Biological Resources 2%5%6%5%8%
20%Surfing Resources 2%5%6%5%6%
20%Aesthetics 3%5%6%5%6%
20%Beach Recreation 2%5%6%5%6%
20%Coastal Access 2%5%8%5%8%
SUBTOTAL out of 40%10%24%34%24%35%
-_3—6—8_—J
1.Lifecycle costs include estimated costs associated with capital,operation &maintenance and estimated adaptation cost at the end of the pilot phase.
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9.3.1 Analysis of Technical Performance Criteria
Each alternative, except for No Project, involves placement of a significant amount of sand over the
design life of the pilot phase. Technical performance was largely based on the ability of each
alternative to restore and retain a beach along the project area. Numerical modeling results indicate
Groins would be most successful in maintaining dry beach area in Oceanside. Multi-purpose Reefs
would also provide a significant improvement over Beach Nourishment. Creation/restoration of a
beach was a key differentiator among the alternatives with the sand retention alternatives (Groins and
Reefs) receiving higher scores due to longer lasting benefits in comparison to Beach Nourishment
alone.
Beach Nourishment is most likely to avoid impacts to down drift sediment supply and received the
highest score for this criterion. Groins and Reefs include a significant amount of beach nourishment
to pre-fill the retention systems and supply down drift beaches with a supply of coarse-grained sand.
Neither of these systems will block longshore sediment transport but there may be an adjustment
period where localized downdrift impacts occur as the beach profiles adjust to the sand retention
system. With some sediment management measures in place during the pilot phase, any potential
down drift impacts could be mitigated. Due to uncertainties over these down drift impacts the Groins
and Reefs received a lower score for this criterion. No Project received the lowest score because this
option provides no reliable supply of coarse sand, so ongoing erosion trends will continue.
Accessibility for safe public access and lifeguard services will be important design elements of each
alternative. Beach Nourishment will improve public safety temporarily after each nourishment event
but will leave long stretches of shoreline inaccessible between nourishment cycles. Groins and Reefs
are more likely to create and retain sandy beach areas to facilitate safe access for the public and
lifeguard services. However, the sand retention structures introduce new risks for ocean recreation
with the potential for rip currents to form in the vicinity of these structures. Due to the various pros and
cons associated with each alternative, they were all assigned mid-range scores since public safety is
not considered a major differentiator between the alternatives.
Adaptability to SLR included consideration for how each alternative could be adapted to perform under
future SLR scenarios up to 2 feet. Restoration of a stable dry beach will help mitigate increased erosion
and storm damage associated with SLR. All alternatives would likely require greater volumes of sand
placement to maintain performance under these future scenarios. Beach Nourishment alone may be
an effective regional solution to SLR but will not be a reliable adaptation strategy for Oceanside without
retention structures. Groins and Reefs would help retain a sandy beach at specific locations providing
a more reliable buffer to SLR and associated storm-related damages. Multi-purpose reefs were scored
highest in terms of adaptability because they also provide increased wave energy dissipation in the
alongshore direction.
9.3.2 Analysis of Financial Criteria
Groins and Beach Nourishment were the highest scoring alternatives in the Financial category. The
Financial score was heavily weighted toward a quantitative estimate of lifecycle costs which
include initial capital investment, beach renourishment and adaptation/structure modification at the [Q]9.3.1 Analysis of Technical Performance Criteria
Each alternative,except for No Project,involves placement of a significant amount of sand over the
design life of the pilot phase.Technical performance was largely based on the ability of each
alternative to restore and retain a beach along the project area.Numerical modeling results indicate
Groins would be most successful in maintaining dry beach area in Oceanside.Multi-purpose Reefs
would also provide a significant improvement over Beach Nourishment.Creation/restoration of a
beach was a key differentiator among the alternatives with the sand retention alternatives (Groins and
Reefs)receiving higher scores due to longer lasting benefits in comparison to Beach Nourishment
alone.
Beach Nourishment is most likely to avoid impacts to down drift sediment supply and received the
highest score for this criterion.Groins and Reefs include a significant amount of beach nourishment
to pre-fill the retention systems and supply down drift beaches with a supply of coarse-grained sand.
Neither of these systems will block longshore sediment transport but there may be an adjustment
period where localized downdrift impacts occur as the beach profiles adjust to the sand retention
system.With some sediment management measures in place during the pilot phase,any potential
down drift impacts could be mitigated.Due to uncertainties over these down drift impacts the Groins
and Reefs received a lower score for this criterion.No Project received the lowest score because this
option provides no reliable supply of coarse sand,so ongoing erosion trends will continue.
Accessibility for safe public access and lifeguard services will be important design elements of each
alternative.Beach Nourishment will improve public safety temporarily after each nourishment event
but will leave long stretches of shoreline inaccessible between nourishment cycles.Groins and Reefs
are more likely to create and retain sandy beach areas to facilitate safe access for the public and
lifeguard services.However,the sand retention structures introduce new risks for ocean recreation
with the potential for rip currents to form in the vicinity of these structures.Due to the various pros and
cons associated with each alternative,they were all assigned mid-range scores since public safety is
not considered a major differentiator between the alternatives.
Adaptability to SLR included consideration for how each alternative could be adapted to perform under
future SLR scenarios up to 2 feet.Restoration ofa stable dry beach will help mitigate increased erosion
and storm damage associated with SLR.All alternatives would likely require greater volumes of sand
placement to maintain performance under these future scenarios.Beach Nourishment alone may be
an effective regional solution to SLR but will not be a reliable adaptation strategy for Oceanside without
retention structures.Groins and Reefs would help retain a sandy beach at specific locations providing
a more reliable buffer to SLR and associated storm-related damages.Multi-purpose reefs were scored
highest in terms of adaptability because they also provide increased wave energy dissipation in the
alongshore direction.
9.3.2 Analysis of Financial Criteria
Groins and Beach Nourishment were the highest scoring alternatives in the Financial category.The
Financial score was heavily weighted toward a quantitative estimate of lifecycle costs which
include initial capital investment,beach renourishment and adaptation/structure modification at the
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end of the pilot phase, which was assumed to be about 15 years. Estimated lifecycle costs are
provided in Table 9-7.
Renourishment is assumed to occur at 5-year intervals for cost estimating purposes but actual timing
would depend on monitoring results. Adaptation costs for the retention alternatives are based on a
percentage of the initial cost of the structures assuming some adjustments or maintenance of these
structures would occur at the end of the pilot phase. No Project costs assume the City contributes to
additional harbor dredging or other opportunistic efforts once every five years. Details of the lifecycle
costs and assumptions made for each alternative are provided in Appendix C.
Beach Nourishment has a lower lifecycle cost than the Groins due to the initial cost of building the
groin structures. The Groins alternative has lower maintenance costs since less volume of
nourishment is required over the project duration. Multi-purpose Reefs received the lowest score since
this alternative was estimated to have the highest lifecycle cost due to the significant volume of
material required to build the artificial reef structures.
A restored sandy beach along the most accessible reaches of the Oceanside shoreline will generate
in-direct economic benefits resulting from increased tourism and recreation visits. Since the sand
retention alternatives are expected to prolong the benefits of a restored sandy beach, these
alternatives were scored higher in this criterion than other alternatives.
Table 9-7. Alternative Lifecycle Cost Estimates
ALTERNATIVE
1 2 3 4
NO PROJECT BEACH
NOURISHMENT GROINS SLRR GROIN
MODS MULTI-PURPOSE
REEFS
Initial Cost $ 1,000,000 $ 10,000,000 $ 32,000,000 $ 16,000,000 $ 95,000,000
Beach Renourishment $ 2,000,000 $ 18,000,000 $ 14,000,000 $ 18,000,000 $ 14,000,000
Adaptation - - $ 5,000,000 $ 2,000,000 $ 39,000,000
Total $ 3,000,000 $ 28,000,000 $ 51,000,000 $ 36,000,000 $ 148,000,000
Notes:
1. The values provided in this table are considered pre-planning level estimates and should not be used
for any purpose other than intended, which is for comparing alternatives for the Project feasibility
analysis. Accuracy +50% - 30%.
2. All values shown in this table are 2021 costs.
3. Please refer to the appendix for breakdown of estimated costs and assumptions for each alternative.
4. A 15-30% contingency amount is included in the estimates to cover unknown detail and costs
considering the feasibility level of the design.
9.3.3 Analysis of Environmental Criteria
Groins and Multi-purpose Reefs scored significantly higher than other alternatives in the
Environmental category. Although some temporary marine biological resource impacts would be [Q]end of the pilot phase,which was assumed to be about 15 years.Estimated lifecycle costs are
provided in Table 9-7.
Renourishment is assumed to occur at 5—year intervals for cost estimating purposes but actual timing
would depend on monitoring results.Adaptation costs for the retention alternatives are based on a
percentage of the initial cost of the structures assuming some adjustments or maintenance of these
structures would occur at the end of the pilot phase.No Project costs assume the City contributes to
additional harbor dredging or other opportunistic efforts once every five years.Details of the lifecycle
costs and assumptions made for each alternative are provided in Appendix C.
Beach Nourishment has a lower lifecycle cost than the Groins due to the initial cost of building the
groin structures.The Groins alternative has lower maintenance costs since less volume of
nourishment is required over the project duration.Multi-purpose Reefs received the lowest score since
this alternative was estimated to have the highest lifecycle cost due to the significant volume of
material required to build the artificial reef structures.
A restored sandy beach along the most accessible reaches of the Oceanside shoreline will generate
in-direct economic benefits resulting from increased tourism and recreation visits.Since the sand
retention alternatives are expected to prolong the benefits of a restored sandy beach,these
alternatives were scored higher in this criterion than other alternatives.
Table 9-7.Alternative Lifecycle Cost Estimates
1 2 3 4ALTERNATIVEBEACHSLRRGROINMULTl-PURPOSE"0 PROJECT NOURISHMENT GRO'NS MODS REEFS
'“itia'‘30“S 1,000,000 S 10,000,000 S 32,000,000 S 16,000,000 $95,000,000
Beach Renourishment S 2,000,000 S 18,000,000 S 14,000,000 S 18,000,000 $14,000,000
Adaptation --5 5,000,000 $2,000,000 $39,000,000
Total $3,000,000 $28,000,000 $51,000,000 $36,000,000 $148,000,000
Notes:
1.The values provided in this table are considered pre—planning level estimates and should not be used
for any purpose other than intended,which is for comparing alternatives for the Project feasibility
analysis.Accuracy +50%—30%.
2.All values shown in this table are 2021 costs.
3.Please refer to the appendix for breakdown of estimated costs and assumptions for each alternative.
4.A 15-30%contingency amount is included in the estimates to cover unknown detail and costs
considering the feasibility level of the design.
9.3.3 Analysis of Environmental Criteria
Groins and Multi-purpose Reefs scored significantly higher than other alternatives in the
Environmental category.Although some temporary marine biological resource impacts would be
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expected for each nourishment event, over longer durations the sand retention alternatives improve
the viability of sandy inter-tidal beach habitat within the project area. The sand retention structures will
occupy sand bottom habitat but will also create rocky intertidal/subtidal habitat over the long-term. The
trade-offs associated with these resource impacts will be a focus of environmental analyses conducted
in subsequent project phases. The retention alternatives (Groins and Reefs) also score slightly higher
than Beach Nourishment in aesthetic, recreation and coastal access due to the pro-longed benefits
associated with sandy beach areas retained.
Surfing resources are an important consideration for each of the alternatives developed. Oceanside
offers a long stretch of beachbreak with a wide exposure to incoming swell from multiple directions. In
recent years, the surfing resources have been adversely impacted by the loss of a sandy beach and
continued erosion of the beach profile in front of the revetment. These conditions render long reaches
of shoreline unrideable during medium-high tides because of the deep nearshore profile and
backwash (i.e. waves rebounding off the revetment into the surfzone).
Alternatives which restore a stable sandy beach along the City are expected to preserve and enhance
existing surfing resources. For this reason, Groins and Reefs were scored slightly higher than Beach
Nourishment because of their improved ability to retain a sandy beach. Groins are a common feature
of surf breaks throughout Southern California and globally with the San Luis Rey River Groin
(commonly referred to as south jetty) one of the most popular surfing resources in the area. Groins
are not expected to significantly alter the surfing resources along Oceanside and there is a potential
they enhance surfing resources due to the occurrence of sandbars which often form in the vicinity of
these structures.
Multi-purpose Reefs are an intriguing alternative for enhancing surfing resources while retaining a
beach but remain expensive and unproven in their ability to provide a consistent and rideable break
in an open ocean environment like Oceanside. This alternative would likely require some adjustments
in the field to mitigate adverse impacts on surfing resources.
9.4 Sensitivity
9.4.1 Criteria Scoring Sensitivity
The MCA scoring matrix generated questions from the Project team regarding sensitivity of the
analysis. The key question being “How would these results change if one or two scores were revised
up or down for each alternative?” There were only a few criteria in which the Project team had more
difficulty arriving at a consensus score for a given alternative. One example was the scoring for
aesthetics, which is somewhat subjective and dependent on a person’s perspective and interests. In
this case, changing a single score by one increment would result in only a 2% change in the total
score. For each alternative there were only one or two criteria in which scoring was debatable and,
therefore, the overall scoring sensitivity was estimated to be 2-4% when considering the total score.
Through this sensitivity analysis it was determined that changes to multiple individual criteria scores
would not change the overall alternative rankings since the top three alternatives have an 8-9%
separation in total score. The results indicate a robust consensus among the Project team that Groins
are the highest scoring alternative in comparison to Multi-purpose Reefs, Beach Nourishment, San
Luis Rey Groin Modification and No Project alternatives. [Q]expected for each nourishment event,over longer durations the sand retention alternatives improve
the viability of sandy inter-tidal beach habitat within the project area.The sand retention structures will
occupy sand bottom habitat but will also create rocky intertidal/subtidal habitat over the long-term.The
trade-offs associated with these resource impacts will be a focus of environmental analyses conducted
in subsequent project phases.The retention alternatives (Groins and Reefs)also score slightly higher
than Beach Nourishment in aesthetic,recreation and coastal access due to the pro-longed benefits
associated with sandy beach areas retained.
Surfing resources are an important consideration for each of the alternatives developed.Oceanside
offers a long stretch of beachbreak with a wide exposure to incoming swell from multiple directions.In
recent years,the surfing resources have been adversely impacted by the loss of a sandy beach and
continued erosion of the beach profile in front of the revetment.These conditions render long reaches
of shoreline unrideable during medium-high tides because of the deep nearshore profile and
backwash (i.e.waves rebounding off the revetment into the surfzone).
Alternatives which restore a stable sandy beach along the City are expected to preserve and enhance
existing surfing resources.For this reason,Groins and Reefs were scored slightly higher than Beach
Nourishment because of their improved ability to retain a sandy beach.Groins are a common feature
of surf breaks throughout Southern California and globally with the San Luis Rey River Groin
(commonly referred to as south jetty)one of the most popular surfing resources in the area.Groins
are not expected to significantly alter the surfing resources along Oceanside and there is a potential
they enhance surfing resources due to the occurrence of sandbars which often form in the vicinity of
these structures.
Multi-purpose Reefs are an intriguing alternative for enhancing surfing resources while retaining a
beach but remain expensive and unproven in their ability to provide a consistent and rideable break
in an open ocean environment like Oceanside.This alternative would likely require some adjustments
in the field to mitigate adverse impacts on surfing resources.
9.4 Sensitivity
9.4.1 Criteria Scoring Sensitivity
The MCA scoring matrix generated questions from the Project team regarding sensitivity of the
analysis.The key question being “How would these results change if one or two scores were revised
up or down for each alternative?”There were only a few criteria in which the Project team had more
difficulty arriving at a consensus score for a given alternative.One example was the scoring for
aesthetics,which is somewhat subjective and dependent on a person’s perspective and interests.In
this case,changing a single score by one increment would result in only a 2%change in the total
score.For each alternative there were only one or two criteria in which scoring was debatable and,
therefore,the overall scoring sensitivity was estimated to be 2-4%when considering the total score.
Through this sensitivity analysis it was determined that changes to multiple individual criteria scores
would not change the overall alternative rankings since the top three alternatives have an 8-9%
separation in total score.The results indicate a robust consensus among the Project team that Groins
are the highest scoring alternative in comparison to Multi-purpose Reefs,Beach Nourishment,San
Luis Rey Groin Modification and No Project alternatives.
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9.4.2 Category Weighting Sensitivity
Sensitivity of Category Weightings was another area of interest to understand how the breakdown
between Technical Performance, Financial and Environmental influences overall results. The results
presented in Section 9.3 are based on a breakdown of 40% for Technical Performance (TP), 20% for
Financial (FIN) and 40% for Environmental (ENV). The consensus of the Project team was that
Technical Performance and Environmental warranted a higher emphasis because their criteria closely
match the Project objectives, feedback from public engagement, and provide the best indicator for
Project success.
Figure 9-1 illustrates the total scores for each alternative for several different Category Weightings.
When these weightings are adjusted a clear pattern emerges in which Groins (Alternative 2) is
consistently scored highest and No Project is consistently scored lowest. If these Category Weightings
are adjusted to place equal emphasis on each category (TP=33.3 / FIN=33.3 / ENV=33.3), the scores
and rankings do not significantly change. If a major emphasis is placed on any single category (60%
weighting), Groins is still the top ranked alternative.
The findings of this sensitivity analysis give the Project team high confidence that Groins have the
best chance to satisfy the Project objectives. Although the Multi-purpose Reefs also scored high in
the Technical Performance and Environmental categories, the low Financial score is an indication this
alternative may be very challenging to fund. [Q]9.4.2 Category Weighting Sensitivity
Sensitivity of Category Weightings was another area of interest to understand how the breakdown
between Technical Performance,Financial and Environmental influences overall results.The results
presented in Section 9.3 are based on a breakdown of 40%for Technical Performance (TP),20%for
Financial (FIN)and 40%for Environmental (ENV).The consensus of the Project team was that
Technical Performance and Environmental warranted a higher emphasis because their criteria closely
match the Project objectives,feedback from public engagement,and provide the best indicator for
Project success.
Figure 9-1 illustrates the total scores for each alternative for several different Category Weightings.
When these weightings are adjusted a clear pattern emerges in which Groins (Alternative 2)is
consistently scored highest and No Project is consistently scored lowest.Ifthese Category Weightings
are adjusted to place equal emphasis on each category (TP=33.3 /F|N=33.3 /ENV=33.3),the scores
and rankings do not significantly change.If a major emphasis is placed on any single category (60%
weighting),Groins is still the top ranked alternative.
The findings of this sensitivity analysis give the Project team high confidence that Groins have the
best chance to satisfy the Project objectives.Although the Multi-purpose Reefs also scored high in
the Technical Performance and Environmental categories,the low Financial score is an indication this
alternative may be very challenging to fund.
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Figure 9-1 Sensitivity to Category Weighting
0%10%20%30%40%50%60%70%80%90%100%
Technical Performance
40%
Financial 20%
Environmental 40%
Technical Performance
60%
Financial 20%
Environmental 20%
Technical Performance20%Financial 60%Environmental 20%
Technical Performance
20%
Financial 20%
Environmental 60%
Technical Performance33.3%Financial 33.3%Environmental 33.3%
No Project
No Project
No Project
No Project
No Project
Beach Nourishment Progam
Beach Nourishment Progam
Beach Nourishment Progam
Beach Nourishment Progam
Beach Nourishment Progam
Groins
Groins
Groins
Groins
Groins
SLRR Groin Modifications
SLRR Groin Modifications
SLRR Groin Modifications
SLRR Groin Modifications
SLRR Groin Modifications
Multi-Purpose Artificial Reef
Multi-Purpose Artificial Reef
Multi-Purpose Artificial Reef
Multi-Purpose Artificial Reef
Multi-Purpose Artificial Reef
CATEGORY WEIGHTING SENSITIVITY ANALYSIS
Multi-Purpose Artificial Reef SLRR Groin Modifications Groins Beach Nourishment Progam No ProjectI9]Technical Performance
33.3%
Financial 33.3%
Environmental 33.3%7
Technical Performance
20%
Financial 20%
Environmental 60%
Technical Performance I
20%
Financial 60%
Environmental 20%
Technical Performance
60%
Financial 20%
Environmental 20%
Technical Performance
40%
Financial 20%
Environmental 40%
CATEGORY WEIGHTING SENSITIVITY ANALYSIS
Multi—Purpose Artificial Reef SLRR Groin Modifications Groins Beach Nourishment Progam No Project
i-Purpose Artificial Reef
Progam
' 'ations
,Groins
ourishment Progam
,Multi-Purpose Artificial Re ef
'Modificatiors
A Groins
Nourishment Progam
WWW/”WWW sLRRGroi Modification
WWW/”WWW Beach Nourishment ProgamJ/No Preject
0°o 10%
2’4"3"_///A Multi-PL rpose Artificial Reef
W//W/fl Groins
20%30% 40% 50%60%70% 80% 90%100%
Figure 9-1 Sensitivity to Category Weighting
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10. Value Comparison, Beach Nourishment vs Sand
Retention
Beach width is an important parameter in evaluating the feasibility of beach nourishment with sand
retention structures. Most of the data presented in this study refers to mean sea level (MSL) beach
width since that is the most common metric reported in the SANDAG RBSP monitoring data. MSL
beach width refers to the distance between the back beach (revetment in most cases) to the MSL
shoreline. This can be a useful metric for documenting shoreline change trends over long time periods
or large areas (i.e. RBSP I and II), but MSL beach width can be a misleading measurement of dry
beach area available for recreation (i.e. towel space).
Figure 10-1 provides a few example profiles of varying beach width to illustrate the difference between
MSL beach width and dry beach width. The May 2012 profile is typical of South Oceanside in which
a submerged beach forms in front of the revetment but there is little or no dry beach to support typical
beach recreation activities. Since the foreshore (beach face) slope is relatively flat in Oceanside, a 50-
foot MSL beach width is submerged half the time, or more depending on wave conditions. In other
words, a 50-foot MSL beach width does not provide enough dry beach for coastal access and
recreation except for some low tide activities.
Figure 10-1. Illustration of MSL Beach Width vs. Dry Beach Width
In order to provide opportunity for coastal access and recreation, the sand retention alternative should
target an MSL beach width of 100 feet or more to provide a sufficient dry beach area to support these
activities. The post RBSP II profiles of May 2013 and 2014 (Figure 4-5) are examples of the dry beach
area available for MSL beach widths of 100-140 feet. Unfortunately, in the case of RBSP II, these
beach widths were short-lived conditions and demonstrate the need for a sand retention system to
prolong these benefits.
The beach area generated over the lifecycle of each alternative provides a useful metric for comparing
the value of each alternative. Modeling results of the pilot-scale sand retention alternatives indicate
they could potentially retain up to 18 acres of beach area, over three times larger than the beach area
generated within the initial placement area after RBSP II. The MSL beach widths in each of the groin
fillets or reef salients would be wide enough and stable enough to support coastal access and [Q]Elevation(Feet,MLLW)Value Comparison,Beach Nourishment vs Sand
Retention
Beach width is an important parameter in evaluating the feasibility of beach nourishment with sand
retention structures.Most of the data presented in this study refers to mean sea level (MSL)beach
width since that is the most common metric reported in the SANDAG RBSP monitoring data.MSL
beach width refers to the distance between the back beach (revetment in most cases)to the MSL
shoreline.This can be a useful metric for documenting shoreline change trends over long time periods
or large areas (i.e.RBSP l and II),but MSL beach width can be a misleading measurement of dry
beach area available for recreation (i.e.towel space).
Figure 10-1 provides a few example profiles of varying beach width to illustrate the difference between
MSL beach width and dry beach width.The May 2012 profile is typical of South Oceanside in which
a submerged beach forms in front of the revetment but there is little or no dry beach to support typical
beach recreation activities.Since the foreshore (beach face)slope is relatively flat in Oceanside,a 50-
foot MSL beach width is submerged half the time,or more depending on wave conditions.In other
words,a 50-foot MSL beach width does not provide enough dry beach for coastal access and
recreation except for some low tide activities.
05-947
-------May 2012 (Pre RBSP ll)
May 2013
May 2014
1(1)150 200 250 300 350 400
Cross-Shore Distance (Feet Seaward ofTransect Origin)
Figure 10-1.Illustration of MSL Beach Width vs.Dry Beach Width
In order to provide opportunity for coastal access and recreation,the sand retention alternative should
target an MSL beach width of 100 feet or more to provide a sufficient dry beach area to support these
activities.The post RBSP ||profiles of May 2013 and 2014 (Figure 4-5)are examples of the dry beach
area available for MSL beach widths of 100-140 feet.Unfortunately,in the case of RBSP ll,these
beach widths were short-lived conditions and demonstrate the need for a sand retention system to
prolong these benefits.
The beach area generated over the lifecycle of each alternative provides a useful metric for comparing
the value of each alternative.Modeling results of the pilot-scale sand retention alternatives indicate
they could potentially retain up to 18 acres of beach area,over three times larger than the beach area
generated within the initial placement area after RBSP II.The MSL beach widths in each of the groin
fillets or reef salients would be wide enough and stable enough to support coastal access and
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recreation on a year-round basis with average beach widths of 100-150 feet. The lifecycle cost of each
alternative was divided by the beach area generated to compare the value (cost/acre of beach area)
of each alternative in Figure 10-2. The alternatives considered all require a large investment, but this
comparison indicates groins would provide the best value in terms of the beach area generated for
the lifecycle cost. While Beach Nourishment has a significantly lower lifecycle cost, the area of beach
generated is also significantly lower. Groins, while requiring a significant capital expense, offer the
highest return on the investment with the best chance of success in providing a stable dry beach along
the pilot reach.
Figure 10-2. Value Comparison for Each Alternative
11. Sand Management Systems Evaluation
Each of the proposed action alternatives require frequent nourishment of City beaches with coarse
gradation sediment. As opposed to developing options of idealized beach nourishment templates and
placement locations, this study focused on identifying sustainable, high quality sand sources and then
developing the mechanisms that could be deployed to transport sand more efficiently to City beaches
that need it most. These options draw upon lessons learned from the City/USACE’s prior Experimental
Sand Bypassing Pilot in the 1980s and more recent successful global project examples.
A critical first step to sediment management in the City is identifying a sustainable source of high-
quality sand. This study identified several sand sources to consider as part of a long-term nourishment
strategy. Each of these sand sources have positive and negative attributes that need to be considered,
as well as potentially significant obstacles to overcome. The sand sources considered in this study
are as follows:
• Camp Pendleton – Unlike most open coast harbors in California, Oceanside Harbor does not
have an established sand bypassing program. As a result, millions of cubic yards of coarse
gradation sand has built up against the northern harbor breakwater (USACE, 2016). This
$-
$1,000,000
$2,000,000
$3,000,000
$4,000,000
$5,000,000
$6,000,000
$7,000,000
$8,000,000
$9,000,000
Beach Nourishment Groins (Pilot)Reefs (Pilot)Cost/acre of beach areaAlternative
Value Comparison[Q]11.
recreation on a year-round basis with average beach widths of 100-150 feet.The lifecycle cost of each
alternative was divided by the beach area generated to compare the value (cost/acre of beach area)
of each alternative in Figure 10-2.The alternatives considered all require a large investment,but this
comparison indicates groins would provide the best value in terms of the beach area generated for
the lifecycle cost.While Beach Nourishment has a significantly lower lifecycle cost,the area of beach
generated is also significantly lower.Groins,while requiring a significant capital expense,offer the
highest return on the investment with the best chance of success in providing a stable dry beach along
the pilot reach.
Value Comparison
$9,000,000
g $8,000,000 —
%$7,000,000 —
g $6,000,000 —
'3 $5,000,000 ——
g $4,000,000 ——
g $3,000,000 ————
8 $2,000,000 —— ——
$1,000,000 ——I __
s-_——_
Beach Nourishment Groins (Pilot)Reefs (Pilot)
Alternative
Figure 10-2.Value Comparison for Each Alternative
Sand Management Systems Evaluation
Each of the proposed action alternatives require frequent nourishment of City beaches with coarse
gradation sediment.As opposed to developing options of idealized beach nourishment templates and
placement locations,this study focused on identifying sustainable,high quality sand sources and then
developing the mechanisms that could be deployed to transport sand more efficiently to City beaches
that need it most.These options draw upon lessons learned from the City/USACE’s prior Experimental
Sand Bypassing Pilot in the 19803 and more recent successful global project examples.
A critical first step to sediment management in the City is identifying a sustainable source of high-
quality sand.This study identified several sand sources to consider as part of a long-term nourishment
strategy.Each of these sand sources have positive and negative attributes that need to be considered,
as well as potentially significant obstacles to overcome.The sand sources considered in this study
are as follows:
0 Camp Pendleton —Unlike most open coast harbors in California,Oceanside Harbor does not
have an established sand bypassing program.As a result,millions of cubic yards of coarse
gradation sand has built up against the northern harbor breakwater (USACE,2016).This
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source of sand is the most logical and economical source to restore a supply of sediment to
Oceanside beaches. The Marine Corps have declined to discuss the feasibility of bypassing
this sand around the harbor to maintain a supply of sand to downdrift beaches. Unfortunately,
this is consistent with past coordination with the Marine Corps about dredging this deposit (i.e.
Sand Bypass Project). Political and jurisdictional challenges remain the most significant
barriers to this sand source.
• San Luis Rey River: A significant deposit of coarse gradation sand exists at the mouth of the
San Luis Rey River. The recharge of this area, once sand is dredged, is unknown but would
likely not be a sustainable long-term source of significant quantities of sediment. While not
sufficient to mitigate the sediment supply deficit, this source of sand is worth consideration as
an opportunistic source to supplement with other efforts. Previous USACE studies have also
evaluated dredging of sediment further upstream to increase conveyance capacity of the river.
The San Luis Rey River mouth area is critical habitat for the Western Snowy Plover and the
tidewater goby. Any dredging activity would include a thorough environmental review of the
potential impacts on ecological functions within the river.
• City of Oceanside Harbor Beach: A fillet of sand exists along the north jetty. This area could
be dredged to form a sediment capture area for sand before entering the harbor. The recharge
of this area, once sand is dredged, is unknown but would likely not be a sustainable long-term
source of significant quantities of sediment.
• Offshore Sediment Deposits: Offshore sediment deposits, like the ones used in RBSP I and
II, are a proven source of sand high in both quantity and quality. These could be dredged
more frequently for local projects but require specialized marine contractors and equipment
to dredge, transport and place material. The high mobilization costs for this type of project
make the economics challenging at the local scale. Since this source requires a different set
of means and methods, it was not included in evaluation of the following sand management
systems.
Once a source of sediment is identified, the next step is to determine how to efficiently move sand
from the source location to the receiving beach. Sediment bypassing is most effective when the sand
source location/borrow area is fixed and the area recharges quickly once dredged. The ability for the
borrow area to recharge was a key limitation of the Experimental Sand Bypassing Pilot, which was
evaluated closely prior to proposing new bypassing options. Other limitations of the bypassing pilot
were pipeline clogging issues and inconsistent federal funding leading to a scaled down pilot project
and deferred maintenance of the system. Options for bypassing sediment in the City are presented in
this section.
11.1 Fixed Trestle Sand Bypass
Similar to the Tweed River Project, this option would construct a fixed trestle updrift of Oceanside
Harbor on Camp Pendleton (Figure 11-1). The trestle would extend into the surfzone/nearshore with
a series of pumps to capture sand moving in the longshore direction. Sand pickup locations would be
optimized based on beach conditions and observed recovery time of the depressions where sand had
been removed. [Q]source of sand is the most logical and economical source to restore a supply of sediment to
Oceanside beaches.The Marine Corps have declined to discuss the feasibility of bypassing
this sand around the harbor to maintain a supply of sand to downdrift beaches.Unfortunately,
this is consistent with past coordination with the Marine Corps about dredging this deposit (i.e.
Sand Bypass Project).Political and jurisdictional challenges remain the most significant
barriers to this sand source.
0 San Luis Rey River:A significant deposit of coarse gradation sand exists at the mouth of the
San Luis Rey River.The recharge of this area,once sand is dredged,is unknown but would
likely not be a sustainable long-term source of significant quantities of sediment.While not
sufficient to mitigate the sediment supply deficit,this source of sand is worth consideration as
an opportunistic source to supplement with other efforts.Previous USACE studies have also
evaluated dredging of sediment further upstream to increase conveyance capacity of the river.
The San Luis Rey River mouth area is critical habitat for the Western Snowy Plover and the
tidewater goby.Any dredging activity would include a thorough environmental review of the
potential impacts on ecological functions within the river.
0 City of Oceanside Harbor Beach:A fillet of sand exists along the north jetty.This area could
be dredged to form a sediment capture area for sand before entering the harbor.The recharge
of this area,once sand is dredged,is unknown but would likely not be a sustainable long-term
source of significant quantities of sediment.
o Offshore Sediment Deposits:Offshore sediment deposits,like the ones used in RBSP l and
II,are a proven source of sand high in both quantity and quality.These could be dredged
more frequently for local projects but require specialized marine contractors and equipment
to dredge,transport and place material.The high mobilization costs for this type of project
make the economics challenging at the local scale.Since this source requires a different set
of means and methods,it was not included in evaluation of the following sand management
systems.
Once a source of sediment is identified,the next step is to determine how to efficiently move sand
from the source location to the receiving beach.Sediment bypassing is most effective when the sand
source location/borrow area is fixed and the area recharges quickly once dredged.The ability for the
borrow area to recharge was a key limitation of the Experimental Sand Bypassing Pilot,which was
evaluated closely prior to proposing new bypassing options.Other limitations of the bypassing pilot
were pipeline clogging issues and inconsistent federal funding leading to a scaled down pilot project
and deferred maintenance of the system.Options for bypassing sediment in the City are presented in
this section.
1 1.1 Fixed Trestle Sand Bypass
Similar to the Tweed River Project,this option would construct a fixed trestle updrift of Oceanside
Harbor on Camp Pendleton (Figure 11-1).The trestle would extend into the surfzone/nearshore with
a series of pumps to capture sand moving in the longshore direction.Sand pickup locations would be
optimized based on beach conditions and observed recovery time of the depressions where sand had
been removed.
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The system would transport pumped sand to City beaches via a network of shallow and deep
underground pipelines. The size and pipeline composition (HDPE or steel) would be determined at a
later phase once sand bypass volumes are finalized. It is proposed that pipelines be constructed
underground (via horizontal directional drilling) under the Oceanside Harbor and the community of
North Coast Village. Four junction boxes are proposed to allow for booster pumps to be added or for
sand to be discharged at these locations. This system would be designed to work with the USACE’s
harbor dredging program. The installation of a fixed distribution system would reduce costs associated
with above-ground pipeline placement, improve public safety and reduce the disruption to public
access and beach uses during each dredging event.
Initially, the system would bypass over 200,000 CY of sand per year to City beaches to make up for
the long-term sediment deficit. Over time, this bypass rate would be reduced to keep pace with
longshore sediment transport rates and maintain a sufficient dry beach area updrift of the harbor.
While requiring a major capital investment, this option avoids the need for mobilization of equipment
and pipeline placement on an annual basis reducing the disruption to beach users at Camp Pendleton
and Oceanside.
[Q]The system would transport pumped sand to City beaches via a network of shallow and deep
underground pipelines.The size and pipeline composition (HDPE or steel)would be determined at a
later phase once sand bypass volumes are finalized.It is proposed that pipelines be constructed
underground (via horizontal directional drilling)under the Oceanside Harbor and the community of
North Coast Village.Fourjunction boxes are proposed to allow for booster pumps to be added or for
sand to be discharged at these locations.This system would be designed to work with the USACE’s
harbor dredging program.The installation of a fixed distribution system would reduce costs associated
with above-ground pipeline placement,improve public safety and reduce the disruption to public
access and beach uses during each dredging event.
Initially,the system would bypass over 200,000 CY of sand per year to City beaches to make up for
the long-term sediment deficit.Over time,this bypass rate would be reduced to keep pace with
longshore sediment transport rates and maintain a sufficient dry beach area updrift of the harbor.
While requiring a major capital investment,this option avoids the need for mobilization of equipment
and pipeline placement on an annual basis reducing the disruption to beach users at Camp Pendleton
and Oceanside.
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Figure 11-1. Fixed Trestle Sand Bypass Option
ammmmm-vlmwrm
Lawn!
led TiestleBypassSystem
-r -—HDDPipeine
HDPEPbd'lle
Water InhkePipeline
—Her
_OutletPipe
-JunctionBox
Pump House
Figure 11-1.Fixed Trestle Sand Bypass Option
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11.2 Semi-fixed Sand Bypass
This option would entail construction of a bypass system that could be moved relatively easily to
accommodate changes in the sand source location. Similar to the fixed system (Figure 11-1), this
option would entail construction of sand distribution pipelines and junction boxes to transport sand
within the City. Unlike the fixed system, this system could source sand from the Camp Pendleton fillet,
Harbor Beach or the SLRR mouth with some manipulation.
This system is envisioned to transport approximately 100,000 CY per year; similar to other comparable
systems. Due to the decreased capacity of the system, nourishment would need to be carried out
frequently; assumed annually for a period of 4-6 months.
The sediment intake at the source location could be similar to the Tweed River Sandshifter that is in
a semi-fixed location within the foreshore (Figure 11-2). Once the system is turned on, the sand above
it is fluidized and pumped into the pipelines forming a depression that is filled by active littoral transport.
Another option for the sediment intake would be to construct something similar to the Indian River Inlet
system. This system entails a fixed pipeline distribution system and pump house but allows for some
flexibility with the intake through manipulating the cutter head dredge with a crane (Figure 11-3).
The semi-fixed sand bypass system avoids the high capital cost of a fixed trestle system. As a result,
the operational and maintenance requirements for this system will be greater and likely require the
mobilization of materials and equipment for each dredging event, depending on the location and
volume to be dredged.
The variable location and quantity is a benefit of this system with the flexibility to access multiple local
sand sources. However, this flexibility poses a challenge when paired with a distribution system that
has a fixed pipeline diameter. It may not be possible to design a one-size fits all distribution system
since the pipe diameter may not be perfectly suited to all dredge equipment and production rates. For
example, if the fixed distribution pipeline is under-sized for a specific dredging event, production rates
will suffer, increasing the duration and costs of each dredging event. On the other hand, if the fixed
system is oversized for a small-scale dredging event, booster pumps may be required to deliver the
sand to the designated downcoast receiver site.
[Q]11.2 Semi-fixed Sand Bypass
This option would entail construction of a bypass system that could be moved relatively easily to
accommodate changes in the sand source location.Similar to the fixed system (Figure 11-1),this
option would entail construction of sand distribution pipelines and junction boxes to transport sand
within the City.Unlike the fixed system,this system could source sand from the Camp Pendleton fillet,
Harbor Beach or the SLRR mouth with some manipulation.
This system is envisioned to transport approximately 100,000 CY per year;similar to other comparable
systems.Due to the decreased capacity of the system,nourishment would need to be carried out
frequently;assumed annually for a period of 4-6 months.
The sediment intake at the source location could be similar to the Tweed River Sandshifter that is in
a semi-fixed location within the foreshore (Figure 11-2).Once the system is turned on,the sand above
it is fluidized and pumped into the pipelines forming a depression that is filled by active littoral transport.
Another option for the sediment intake would be to construct something similar to the Indian River Inlet
system.This system entails a fixed pipeline distribution system and pump house but allows for some
flexibility with the intake through manipulating the cutter head dredge with a crane (Figure 11-3).
The semi-fixed sand bypass system avoids the high capital cost of a fixed trestle system.As a result,
the operational and maintenance requirements for this system will be greater and likely require the
mobilization of materials and equipment for each dredging event,depending on the location and
volume to be dredged.
The variable location and quantity is a benefit of this system with the flexibility to access multiple local
sand sources.However,this flexibility poses a challenge when paired with a distribution system that
has a fixed pipeline diameter.It may not be possible to design a one-size fits all distribution system
since the pipe diameter may not be perfectly suited to all dredge equipment and production rates.For
example,if the fixed distribution pipeline is under-sized for a specific dredging event,production rates
will suffer,increasing the duration and costs of each dredging event.On the other hand,if the fixed
system is oversized for a small-scale dredging event,booster pumps may be required to deliver the
sand to the designated downcoast receiver site.
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Figure 11-2. Mobile Sand Bypass Option – Sandshifter Detail (Swash, 2021)
[Q]Figure 11-2.Mobile Sand Bypass Option —Sandshifter Detail (Swash,2021)
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Figure 11-3. Mobile Sand Bypass Option – Indian River Inlet, Delaware (USACE,
2021)
11.3 Piggyback on USACE Harbor Dredging Program
This option would install the proposed series of underground pipelines described in the above options
without purchasing mechanical dredge equipment. This option assumes the City would “piggyback”
on the USACE’s annual harbor dredging program to bypass sand from the MCB Camp Pendleton fillet
using the sand distribution system shown in Figure 11-4. Piggybacking on other dredging operations
is a common practice to and saves on contractor mobilization/demobilization costs. Logistics
surrounding how to access and dredge the fillet would require further coordination with the dredge
contractor and the MCB Camp Pendleton.
The series of sand distribution pipelines would be designed to allow for the efficient distribution of
sand from the navigation channel and fillet to southern portions of the City past known constriction
points (i.e. North Coast Village and Pier). This system would be similar to underground pipelines used
for the Santa Barbara Harbor dredging and the Channel Islands Harbor bypassing programs. Having
fixed underground pipelines would benefit the USACE’s program in that it would lower mobilization
costs. They could also reduce the amount of heavy equipment on the beach during construction, which
would benefit public safety. [Q]Figure 11-3.Mobile Sand Bypass Option —Indian River Inlet,Delaware (USAGE,
2021)
11.3 Piggyback on USAGE Harbor Dredging Program
This option would install the proposed series of underground pipelines described in the above options
without purchasing mechanical dredge equipment.This option assumes the City would “piggyback”
on the USACE’s annual harbor dredging program to bypass sand from the MCB Camp Pendleton fillet
using the sand distribution system shown in Figure 11-4.Piggybacking on other dredging operations
is a common practice to and saves on contractor mobilization/demobilization costs.Logistics
surrounding how to access and dredge the fillet would require further coordination with the dredge
contractor and the M03 Camp Pendleton.
The series of sand distribution pipelines would be designed to allow for the efficient distribution of
sand from the navigation channel and fillet to southern portions of the City past known constriction
points (i.e.North Coast Village and Pier).This system would be similar to underground pipelines used
for the Santa Barbara Harbor dredging and the Channel Islands Harbor bypassing programs.Having
fixed underground pipelines would benefit the USACE’s program in that it would lower mobilization
costs.They could also reduce the amount of heavy equipment on the beach during construction,which
would benefit public safety.
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Figure 11-4. Piggyback on USACE Program Option – Sand Distribution System
Laguiu
Sand DistributionSystem
HDD Pipeline
HDPE Pipeline
Outlet Pipe
-Jucnon Box
Figure 11-4.Piggyback on USACE Program Option —Sand Distribution System
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11.4 Comparison of Sand Distribution Systems
Sand bypass systems have the limitation of being expensive to construct and sometimes difficult to
maintain. However, bypassing works well in situations where large quantities of sediment needs to be
moved around impediments, like the Oceanside harbor. In these scenarios, the comparative costs of
constructing a sand distribution system can be cheaper and less disruptive than conducting one-off
dredging episodes on an annual basis or even more frequently.
The sand distribution systems presented in this section are compared in Table 11-1. Without having
secured a significant source of high-quality sand for the City, there is limited benefit to further design
and analysis. The ideal sand source for a sand bypass system is the MCB Camp Pendleton fillet
despite the significant political and jurisdictional obstacles that exist. Should that sand source become
available, a semi-fixed sand distribution system should be evaluated in more detail and designed to
work with the USACE’s annual harbor dredging program. A pilot, or proof-of-concept could be carried
out at harbor beach with the system to raise the level of comfort with the MCB, if deemed necessary
and appropriate. [Q]11.4 Comparison of Sand Distribution Systems
Sand bypass systems have the limitation of being expensive to construct and sometimes difficult to
maintain.However,bypassing works well in situations where large quantities of sediment needs to be
moved around impediments,like the Oceanside harbor.In these scenarios,the comparative costs of
constructing a sand distribution system can be cheaper and less disruptive than conducting one-off
dredging episodes on an annual basis or even more frequently.
The sand distribution systems presented in this section are compared in Table 11-1.Without having
secured a significant source of high-quality sand for the City,there is limited benefit to further design
and analysis.The ideal sand source for a sand bypass system is the MCB Camp Pendleton fillet
despite the significant political and jurisdictional obstacles that exist.Should that sand source become
available,a semi-fixed sand distribution system should be evaluated in more detail and designed to
work with the USACE’s annual harbor dredging program.A pilot,or proof-of-concept could be carried
out at harbor beach with the system to raise the level of comfort with the MCB,if deemed necessary
and appropriate.
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Table 11-1. Comparison of Sand Management Systems
System
Approx.
Capital
Costs
(USD,
Million)
Approx.
Annual
Operation &
Maintenance
Costs (USD,
Million)
Assumed
Annual
Bypass Yield
(thousand,
CY)
Pros Cons
Fixed Trestle
Sand
Bypass
$36 $5.2 100 - 300
• Can bypass large quantities of high-quality sand to
facilitate beach accretion in Oceanside.
• Bypassed sand volumes could be scaled up or
down based on need.
• Multiple pump intakes allow for flexibility in
sourcing sand from surfzone/inter-tidal.
• Improved public safety & beach access (no pipe)
• Expensive to construct and operate.
• Dependent on recharge of surfzone/inter-tidal
sand depressions.
• Requires MCB Camp Pendleton cooperation.
Semi-fixed
Sand
Bypass
$11M $0.2 50 - 100
• Lower capital cost to construct
• Bypassed sand volume could be scaled up or down
based on need.
• Mobility of intakes allow for some flexibility in sand
sourcing.
• Improved public safety & beach access (no pipe)
• Difficulty in designing a one-size fits all
pipeline distribution system.
• Higher costs to operate & maintain for each
event.
• More uncertainty in annual bypass volumes
• Requires MCB Camp Pendleton cooperation.
Piggyback
on USACE
Harbor
Dredging
Program
$9M $0.2 50 - 100
• Reduce mob/demob costs for sand bypassing
• Same equipment performs harbor dredging and
bypassing
• Fixed pipeline benefits USACE program
• Improved public safety & beach access (no pipe)
• Dependent on contractor/equipment used for
harbor dredging
• Requires MCB Camp Pendleton cooperation. [9]Approx.
Capital
Costs
(USD,
Million)
System
Table 11-1.Comparison of Sand Management Systems
Approx.AssumedAnnual_AnnualOperatlon&Bypass YieldMaintenance(thousand,Costs (USD,CY)Million)
0 Can bypass large quantities of high-quality sand to
facilitate beach accretion in Oceanside..Expensive to construct and operate.
Fixed Trestle °Bypassed sand volumes COUId be scaled up or o Dependent on recharge of surfzone/inter—tidal
Sand $36 $5.2 100 -300 down based on need.sand depressions.
Bypass 'Multlple pump Intakes allow for flex'b'l'ty 'n o Requires MCB Camp Pendleton cooperation.
sourcing sand from surfione/inter—tidal.
-Improved public safety &beach access (no pipe)
0 Difficulty in designing a one-size fits all
0 Lower capltal cost to construct pipeline distribution system.
_-Bypassed sand volume could be scaled up or down .Higher costs to operate &maintain for each
Semi-fixed based on need.eventSand$11M $0.2 50 —100 M b'l'f_t k ll f fl 'b'l'_d -
'0 ''ty 0 'n a es a 0‘”or some 6)"'W 'n san -More uncertainty in annual bypass volumesBypasssourcing.---ReqUIres MCB Camp Pendleton cooperation.
-Improved public safety &beach access (no pipe)
Piggyback 0 Reduce mob/demob costs for sand bypassing
on USACE .Same equipment performs harbor dredging and -Dependent on contractor/equipment used for
Harbor $9M $0.2 50 —100 bypassing harbor dredging
Dredging .Fixed pipeline benefits USACE program -Requires MCB Camp Pendleton cooperation.
Program 0 Improved public safety &beach access (no pipe)
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12. Conclusions
Since construction of the Oceanside Harbor complex 80 years ago, the City of Oceanside and USACE
have struggled to offset the erosional impacts to downdrift beaches. The current condition of South
Oceanside beaches are dismal for beach recreation, with many areas having little to no dry beach
during the majority of the tidal cycle. Wave events are impacting coastal infrastructure with greater
frequency and severity, resulting in the need for repairs and improvements to shoreline protection
systems. Projected sea level rise threatens to make these conditions worse. The primary coastal
challenges are as follows:
• Oceanside Harbor Complex blocks littoral drift. The natural supply of coarse-gradation
sand is impounded in the upcoast fillet which has formed a 400-500 foot wide dry beach along
Camp Pendleton’s Del Mar Beach Resort. Only a small fraction of the net longshore sediment
transport volume reaches the harbor and only consists of fine-grained sediment.
• Limited beach gains from USACE Harbor Dredging. The timing, sediment type and
placement locations are insufficient to mitigate the sediment supply deficit. The fine-grained
sediment disperses low on the beach profile, providing limited dry beach.
• Poor performance of Regional Beach Fills. While these projects added coarse sand to a
sediment starved coastline, the benefits along Oceanside beaches were short-lived.
Oceanside sand moved downcoast soon after placement, accumulating in the fillet upcoast
of the north groin at Agua Hedionda Lagoon.
• Difficulty Reaching Social, Political & Regulatory Consensus. Potential downdrift
impacts, costs, environmental and recreational impacts are valid concerns that need to be
addressed. Unfortunately, social, political and regulatory interests don’t always align in how
to address these concerns. These have been key issues in the long history of addressing
coastal challenges in Oceanside.
Of the four alternatives developed and evaluated in this study, Groins scored the highest based on a
multi-criteria analysis based on Technical Performance, Financial and Environmental considerations.
Groins require a larger capital expense than Beach Nourishment alone but offer the highest return on
the investment with the best chance of success in providing a stable dry beach along the pilot reach.
Estimated cost per acre of beach area was $2.8M/acre for Groins, compared to $4.6M/acre for Beach
Nourishment.
GHD recommends the Groins pilot-scale concept be advanced for further analysis, additional
public/agency outreach and preliminary design to prepare for the environmental review and permitting
process. Additional analysis of the groin field pilot would involve sensitivity analyses on groin length
and spacing, the pre-fill volumes and sand management systems required to mitigate potential
impacts.
Without having secured a significant source of high-quality sand for the City, there is limited benefit to
further design and analysis of a sand bypass system. The ideal sand source for a sand bypass system
is the MCB Camp Pendleton fillet despite the significant political and jurisdictional obstacles that exist.
Conclusions
Since construction of the Oceanside Harbor complex 80 years ago,the City of Oceanside and USACE
have struggled to offset the erosional impacts to downdrift beaches.The current condition of South
Oceanside beaches are dismal for beach recreation,with many areas having little to no dry beach
during the majority of the tidal cycle.Wave events are impacting coastal infrastructure with greater
frequency and severity,resulting in the need for repairs and improvements to shoreline protection
systems.Projected sea level rise threatens to make these conditions worse.The primary coastal
challenges are as follows:
.Oceanside Harbor Complex blocks littoral drift.The natural supply of coarse-gradation
sand is impounded in the upcoast fillet which has formed a 400-500 foot wide dry beach along
Camp Pendleton’s Del Mar Beach Resort.Only a small fraction ofthe net longshore sediment
transport volume reaches the harbor and only consists of fine-grained sediment.
0 Limited beach gains from USACE Harbor Dredging.The timing,sediment type and
placement locations are insufficient to mitigate the sediment supply deficit.The fine-grained
sediment disperses low on the beach profile,providing limited dry beach.
0 Poor performance of Regional Beach Fills.While these projects added coarse sand to a
sediment starved coastline,the benefits along Oceanside beaches were short-lived.
Oceanside sand moved downcoast soon after placement,accumulating in the fillet upcoast
of the north groin at Agua Hedionda Lagoon.
0 Difficulty Reaching Social,Political &Regulatory Consensus.Potential downdrift
impacts,costs,environmental and recreational impacts are valid concerns that need to be
addressed.Unfortunately,social,political and regulatory interests don’t always align in how
to address these concerns.These have been key issues in the long history of addressing
coastal challenges in Oceanside.
Of the four alternatives developed and evaluated in this study,Groins scored the highest based on a
multi-criteria analysis based on Technical Performance,Financial and Environmental considerations.
Groins require a larger capital expense than Beach Nourishment alone but offer the highest return on
the investment with the best chance of success in providing a stable dry beach along the pilot reach.
Estimated cost per acre of beach area was $2.8M/acre for Groins,compared to $4.6M/acre for Beach
Nourishment.
GHD recommends the Groins pilot-scale concept be advanced for further analysis,additional
public/agency outreach and preliminary design to prepare for the environmental review and permitting
process.Additional analysis of the groin field pilot would involve sensitivity analyses on groin length
and spacing,the pre-fill volumes and sand management systems required to mitigate potential
impacts.
Without having secured a significant source of high-quality sand for the City,there is limited benefit to
further design and analysis of a sand bypass system.The ideal sand source for a sand bypass system
is the MCB Camp Pendleton fillet despite the significant political and jurisdictional obstacles that exist.
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Should that sand source become available, the Semi-fixed Sand Bypass or USACE Piggyback option
should be evaluated more closely to determine the most cost-effective solution.
[Q]Should that sand source become available,the Semi-fixed Sand Bypass or USACE Piggyback option
should be evaluated more closely to determine the most cost-effective solution.
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13. Next Steps
Recommended next steps are as follows:
- Agency and Stakeholder Coordination & Engagement:
o Overcoming the social, political and regulatory challenges surrounding the use of sand
retention structures is going to require continued coordination with key agencies and
stakeholders to address concerns surrounding downdrift impacts, recreational impacts
and precedent-setting type concerns. Key agencies to continue to engage include the CA
Coastal Commission, Surfrider Foundation and other non-government agencies that have
expressed concern.
o Access to the sand source along the northern fillet is also a critical element in making any
sand bypassing option viable. Engagement with the MCB Camp Pendleton at the
appropriate level is also a key next step to securing a sustainable, high-quality source of
sand and progressing sand bypassing options.
- Further Refine Groin Design:
o Further engineering analysis and design of the groin concept is needed to refine the
length, spacing, location, and structural details of these structures. The volume and
distribution of the initial nourishment will also depend on this additional analysis and
design effort.
o Development adaptive management plan to address public, agency and stakeholder
concerns about potential impacts. The plan will identify triggers where action would be
taken to remedy an impact, if realized. The plan would be informed by the scientific
monitoring program.
- Enhance Beach Data Monitoring Efforts: Beach width data is important to understand changes
and base management decisions on. Establishing a baseline of data will also be useful should a
sand retention pilot be constructed. The following monitoring actions are recommended:
o Continue to support tracking of subaerial beach widths (dry beach) with the citizen science
program conducted by SOS and others in coordination with SIO.
o Annual to bi-annual, high resolution beach and nearshore SIO “Jumbo Surveys” are
recommended to track the spatial and temporal changes in sand in the City. These
surveys supplement the subaerial surveys and provide a greater level of detail than the
existing regional transect monitoring program.
- Develop Project Financing Strategy: Any of the alternatives considered will require a significant
amount of capital and operational expenditure. Financing strategies should be considered in
concert with seeking state and federal grant funds for the Project.
- Stay Actively Engaged in Local and Regional Sediment Management Activities: The City
should remain actively engaged in ongoing management activities and seek new sources of sand,
as they become available. This recommendation works in concert with the sediment retention
ED
13.Next Steps
Recommended next steps are as follows:
-Agency and Stakeholder Coordination &Engagement:
0 Overcoming the social,political and regulatory challenges surrounding the use of sand
retention structures is going to require continued coordination with key agencies and
stakeholders to address concerns surrounding downdrift impacts,recreational impacts
and precedent-setting type concerns.Key agencies to continue to engage include the CA
Coastal Commission,Surfrider Foundation and other non-government agencies that have
expressed concern.
Access to the sand source along the northern fillet is also a critical element in making any
sand bypassing option viable.Engagement with the MCB Camp Pendleton at the
appropriate level is also a key next step to securing a sustainable,high-quality source of
sand and progressing sand bypassing options.
-Further Refine Groin Design:
0 Further engineering analysis and design of the groin concept is needed to refine the
length,spacing,location,and structural details of these structures.The volume and
distribution of the initial nourishment will also depend on this additional analysis and
design effort.
Development adaptive management plan to address public,agency and stakeholder
concerns about potential impacts.The plan will identify triggers where action would be
taken to remedy an impact,if realized.The plan would be informed by the scientific
monitoring program.
-Enhance Beach Data Monitoring Efforts:Beach width data is important to understand changes
and base management decisions on.Establishing a baseline of data will also be useful should a
sand retention pilot be constructed.The following monitoring actions are recommended:
0
0
Continue to support tracking of subaerial beach widths (dry beach)with the citizen science
program conducted by 808 and others in coordination with SIC.
Annual to bi-annual,high resolution beach and nearshore SIO “Jumbo Surveys”are
recommended to track the spatial and temporal changes in sand in the City.These
surveys supplement the subaerial surveys and provide a greater level of detail than the
existing regional transect monitoring program.
-Develop Project Financing Strategy:Any of the alternatives considered will require a significant
amount of capital and operational expenditure.Financing strategies should be considered in
concert with seeking state and federal grant funds for the Project.
-Stay Actively Engaged in Local and Regional Sediment Management Activities:The City
should remain actively engaged in ongoing management activities and seek new sources of sand,
as they become available.This recommendation works in concert with the sediment retention
GHD |Beach Sand Replenishment &Retention Device Project |June 2021 |Page 76Jan. 4, 2022 Item 4 Page 90 of 229
GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 77
project as local sediment management activities alone will lack the magnitude or quality to sustain
beaches in the city.
o Continue to engage with the USACE on annual harbor dredging program activities. The
timing, placement methods and locations should be discussed to see if they can be
modified to increase local benefits.
o Continue to seek opportunistic sources of sand (i.e. San Luis Rey River, Buena Vista
Lagoon Restoration, etc.) for beach nourishment. Maintain City’s permits for the
Opportunistic Beach Fill Program to streamline approval of these sand sources as they
become available.
o Continue to participate in future SANDAG regional beach sand projects with consideration
for different placement locations, quantities or timing within the City to increase local
benefits.
[Q]project as local sediment management activities alone will lack the magnitude or quality to sustain
beaches in the city.
0 Continue to engage with the USACE on annual harbor dredging program activities.The
timing,placement methods and locations should be discussed to see if they can be
modified to increase local benefits.
Continue to seek opportunistic sources of sand (i.e.San Luis Rey River,Buena Vista
Lagoon Restoration,etc.)for beach nourishment.Maintain City’s permits for the
Opportunistic Beach Fill Program to streamline approval of these sand sources as they
become available.
Continue to participate in future SANDAG regional beach sand projects with consideration
for different placement locations,quantities or timing within the City to increase local
benefits.
GHD |Beach Sand Replenishment &Retention Device Project |June 2021 |Page 77Jan. 4, 2022 Item 4 Page 91 of 229
GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 78
14.References
1. Boswood, P.K. & Murray R.J. 2001. World-wide Sand Bypassing Systems: Data report.
Conservation Technical Report No. 15. Queensland Government. Retrieved from:
https://tamug-
ir.tdl.org/bitstream/handle/1969.3/28472/US%20ACE%20Report.on.Bypass.Systems..pdf?seq
uence=1
2. Coastal Frontiers Corporation. 2020. Regional Beach Monitoring Program Annual Report.
Retrieved from: https://www.sandag.org/index.asp?projectid=298&fuseaction=projects.detail
3. Dean, R. G. 1991. “Equilibrium beach profiles: characteristics and applications.” Journal of
Coastal Research 7, no 1 (Winter 1991). 53-84. ISSN 0749-020
4.Flick, R.E. 1993. “The myth and reality of southern California beaches.” Shore and Beach 61,
no. 3. 3-13.
5.Jenkins, D. L. and Inman, S.A. 2003. “Accretion and erosion waves on beaches.” Encyclopedia
of Coastal Science. (June 2020).
6.Griggs et al. 2020. “Groins, Sand Retention and the Future of Southern California Beaches.”
Shore and Beach 88, no. 2 (May 2020). 1-23. DOI: 10.34237/1008822
7. Moffatt & Nichol Engineers. (1982). Experimental Sand Bypass System at Oceanside Harbor,
California.
8. Moffatt & Nichol Engineers. (2001). Regional Beach Sand Retention Strategy. Retrieved from:
https://www.sandag.org/uploads/publicationid/publicationid_2036_20694.pdf
9. Moffatt & Nichol Engineers. (2016) San Diego County Shoreline Protection Feasibility Study,
Final Sampling Analysis Plan Results Report.
10.NOAA CO-OPS, 2020. https://tidesandcurrents.noaa.gov/met.html?id=9410230 . Date
accessed: 07/30/2020.
11. Noble Consultants, Inc. 1983. Preliminary Engineering Report. Beach Protection Facilities:
Oceanside, California.
12. Noble Consultants, Inc. 2001. Final Construction Management Documents, San Diego
Regional Beach Sand Project. Irvine, CA.
13. O’Hara. Susan P., Graves, Gregory (O’Hara & Graves), 1991. Savings California’s Coast:
Army Engineers at Oceanside and Humboldt Bay. The Arthur H. Clark Company.
14. San Diego Association of Governments (SANDAG). 2020. Regional Shoreline Monitoring
Program Data and Photos.
https://www.sandag.org/index.asp?projectid=298&fuseaction=projects.detail
15. TekMarine, Inc. 1987. Oceanside Littoral Cell Preliminary Sediment Budget Report. Coast of
California Storm and Tidal Waves Study, CCSTWS 87-4.[9]References
10.
11.
12.
13.
14.
15.
Boswood,P.K.&Murray R.J.2001.World-wide Sand Bypassing Systems:Data report.
Conservation Technical Report No.15.Queensland Government.Retrieved from:
https:l/tamug-
ir.td|.org/bitstream/handle/1969.3/28472/US%20ACE%2OReport.on.Bypass.Systems..pdf?seq
uence=1
Coastal Frontiers Corporation.2020.Regional Beach Monitoring Program Annual Report.
Retrieved from:https:/lwww.sandag.org/index.asp?projectid=298&fuseaction=projects.detail
Dean,R.G.1991.“Equilibrium beach profiles:characteristics and applications.”Journal of
Coastal Research 7,no 1 (Winter 1991).53-84.ISSN 0749-020
Flick,RE.1993.“The myth and reality of southern California beaches.”Shore and Beach 61,
no.3.3-13.
Jenkins,D.L.and Inman,SA.2003.“Accretion and erosion waves on beaches."Encyclopedia
of Coastal Science.(June 2020).
Griggs et al.2020.“Groins,Sand Retention and the Future of Southern California Beaches.”
Shore and Beach 88,no.2 (May 2020).1-23.DOI:10.34237/1008822
Moffatt &Nichol Engineers.(1982).Experimental Sand Bypass System at Oceanside Harbor,
California.
Moffatt &Nichol Engineers.(2001).Regional Beach Sand Retention Strategy.Retrieved from:
https:/lwww.sandag.org/uploads/publicationid/publicationid_2036_20694.pdf
Moffatt &Nichol Engineers.(2016)San Diego County Shoreline Protection Feasibility Study,
Final Sampling Analysis Plan Results Report.
NOAA CO-OPS,2020.https:/ltidesandcurrents.noaa.gov/met.html?id=9410230 .Date
accessed:07/30/2020.
Noble Consultants,Inc.1983.Preliminary Engineering Report.Beach Protection Facilities:
Oceanside,California.
Noble Consultants,Inc.2001.Final Construction Management Documents,San Diego
Regional Beach Sand Project.Irvine,CA.
O’Hara.Susan P.,Graves,Gregory (O’Hara &Graves),1991.Savings California's Coast:
Army Engineers at Oceanside and Humboldt Bay.The Arthur H.Clark Company.
San Diego Association of Governments (SANDAG).2020.Regional Shoreline Monitoring
Program Data and Photos.
https:/lwww.sandag.org/index.asp?projectid=298&fuseaction=projects.detail
TekMarine,Inc.1987.Oceanside Littoral Cell Preliminary Sediment Budget Report.Coast of
California Storm and Tidal Waves Study,CCSTWS 87-4.
GHD |Beach Sand Replenishment &Retention Device Project |June 2021 |Page 78Jan. 4, 2022 Item 4 Page 92 of 229
GHD | Beach Sand Replenishment & Retention Device Project | June 2021 | Page 79
16. United States Army Corps of Engineers (USACE). 1980. Oceanside Harbor and Beach,
California. Design of Structures for Harbor Improvement and Beach Erosion Control;
Hydraulic Model Investigation. Hydraulics Laboratory, USACE Waterways Experiment Station.
Technical Report HL-80-10. Retrieved from
https://babel.hathitrust.org/cgi/pt?id=mdp.39015086525840&view=1up&seq=1
17. United States Army Corps of Engineers (USACE). 1991. California Coastal Storm and Tidal
Waves Study for San Diego.
18. United States Army Corps of Engineers (USACE). 1994. Oceanside Shoreline
Reconnaissance Report
19. United States Army Corps of Engineers (USACE). 1995. Sand Bypass System-Phase III
Oceanside Harbor. Construction Solicitation and Specifications. RFP No. DACW09-95-R-
0013.
20. United States Army Corps of Engineers (USACE). 1996. Oceanside Sand Bypass Removal.
Construction Solicitation and Specifications. IFB No. DACW09-96-B-0024.
21. United States Army Corps of Engineers (USACE). 2016. San Diego County Shoreline
Feasibility Study, City of Oceanside, Report Synopsis.
22. United States Army Corps of Engineers. (USACE). 2018. Final Sampling and Analysis Report,
2017-2018 Oceanside Harbor Geotechnical and Environmental Investigation Project. USACE
Los Angeles District. Published June 8, 2018.
23. United States Army Corps of Engineers (USACE). 2021. Delaware Coast Protection, Sand
Bypass Plant, Indian River Inlet. USACE PHILADELPHIA DISTRICT. Published July 2, 2021.
Accessed from https://www.nap.usace.army.mil/Missions/Factsheets/Fact-Sheet-Article-
View/Article/490790/delaware-coast-protection-sand-bypass-plant-indian-river-inlet/
24. Swash Project Delivery. Sand Management in Action. Information of the Noosa Sand Bypass
System. Accessed from https://www.swashpd.com.au/sand-management-in-action/.
[Q]16.
17.
18.
19.
20.
21.
22.
23.
24.
United States Army Corps of Engineers (USACE).1980.Oceanside Harbor and Beach,
California.Design of Structures for Harbor Improvement and Beach Erosion Control;
Hydraulic Model Investigation.Hydraulics Laboratory,USACE WatenNays Experiment Station.
Technical Report HL-80-10.Retrieved from
https://babel.hathitrust.org/cgi/pt?id=mdp.39015086525840&view=1up&seq=1
United States Army Corps of Engineers (USACE).1991.California Coastal Storm and Tidal
Waves Study for San Diego.
United States Army Corps of Engineers (USACE).1994.Oceanside Shoreline
Reconnaissance Report
United States Army Corps of Engineers (USACE).1995.Sand Bypass System-Phase III
Oceanside Harbor.Construction Solicitation and Specifications.RFP No.DACW09-95-R—
0013.
United States Army Corps of Engineers (USACE).1996.Oceanside Sand Bypass Removal.
Construction Solicitation and Specifications.lFB No.DACW09-96-B-0024.
United States Army Corps of Engineers (USACE).2016.San Diego County Shoreline
Feasibility Study,City of Oceanside,Report Synopsis.
United States Army Corps of Engineers.(USACE).2018.Final Sampling and Analysis Report,
2017-2018 Oceanside Harbor Geotechnical and Environmental Investigation Project.USACE
Los Angeles District.Published June 8,2018.
United States Army Corps of Engineers (USACE).2021.Delaware Coast Protection,Sand
Bypass Plant,Indian River Inlet.USACE PHILADELPHIA DISTRICT.Published July 2,2021.
Accessed from https://www.nap.usace.army.miIIMissions/Factsheets/Fact—Sheet—Article-
View/Article/490790/delaware-coast-protection-sand-bypass-plant—indian-river—inlet/
Swash Project Delivery.Sand Management in Action.Information of the Noosa Sand Bypass
System.Accessed from https://www.swashpd.com.au/sand-management—in-actionl.
GHD |Beach Sand Replenishment &Retention Device Project |June 2021 |Page 79Jan. 4, 2022 Item 4 Page 93 of 229
APPENDIX A
Data Gathering Memorandum
APPENDIX A
Data Gathering Memorandum
Jan. 4, 2022 Item 4 Page 94 of 229
APPENDIX A
Data Gathering Memorandum
This appendix presents a summary of the data, literature, and relevant projects that were reviewed for
the City of Oceanside (City) as part of the Sand Replenishment and Retention Device feasibility study.
1. Local Data Review
A thorough understanding of the environmental conditions and coastal processes along the City
shoreline and adjacent beaches is necessary to develop and evaluate viable solutions for shoreline
erosion. The review including downloading and analyzing measured data sets for the following
parameters:
• Water levels
• Winds
• Waves
• Bathymetry and topography
• Seabed surface and sub-surface conditions
• Sediment grain size.
These data are summarized in this section.
1.1 Hydrodynamic Data
1.1.1 Water Levels
The National Oceanic and Atmospheric Administration (NOAA) Center for Operational Oceanographic
Products and Services (CO-OPS) maintains tide stations throughout the United States. The stations
provide water level, current, and meteorological data depending upon the type of sensors installed.
The nearest buoy to the project site is in La Jolla, about 24 miles south-southeast of Oceanside. Table
1-1 provides the tidal datums relative to both mean lower low water (MLLW) and North American
Vertical Datum 1988 (NAVD88). This station has a significant historical data record, having been
established in August 1924.
Table 1-1. Water Levels for La Jolla (Station 9410230)
Datum MLLW (ft) NAVD88 (ft)
Highest Observed (11/25/2015)* 7.81 7.62
Highest Astronomical Tide 7.14 6.95
Mean Higher High Water (MHHW) 5.32 5.13
Mean High Water (MHW) 4.60 4.41
Mean Tide Level (MTL) 2.75 2.56 [9]APPENDIX A
Data Gathering Memorandum
This appendix presents a summary of the data,literature,and relevant projects that were reviewed for
the City of Oceanside (City)as part of the Sand Replenishment and Retention Device feasibility study.
Local Data Review
A thorough understanding of the environmental conditions and coastal processes along the City
shoreline and adjacent beaches is necessary to develop and evaluate viable solutions for shoreline
erosion.The review including downloading and analyzing measured data sets for the following
parameters:
0 Water levels
0 Winds
o Waves
0 Bathymetry and topography
o Seabed surface and sub-surface conditions
0 Sediment grain size.
These data are summarized in this section.
1 .1 Hydrodynamic Data
1.1.1 Water Levels
The National Oceanic and Atmospheric Administration (NOAA)Center for Operational Oceanographic
Products and Services (CO-OPS)maintains tide stations throughout the United States.The stations
provide water level,current,and meteorological data depending upon the type of sensors installed.
The nearest buoy to the project site is in La Jolla,about 24 miles south-southeast of Oceanside.Table
1-1 provides the tidal datums relative to both mean lower low water (MLLW)and North American
Vertical Datum 1988 (NAVD88).This station has a significant historical data record,having been
established in August 1924.
Table 1-1.Water Levels for La Jolla (Station 9410230)wvw waswHighestObserved(11/25/2015)*7.81 7.62
Highest Astronomical Tide 7.14 6.95
Mean Higher High Water (MHHW)5.32 5.13
Mean High Water (MHW)4.60 4.41
Mean Tide Level (MTL)2.75 2.56
Jan. 4, 2022 Item 4 Page 95 of 229
Datum MLLW (ft) NAVD88 (ft)
Mean Sea Level (MSL) 2.73 2.54
NAVD88 0.19 0.00
Mean Low Water (MLW) 0.90 0.71
Mean Lower Low Water (MLLW) 0.00 -0.19
Lowest Astronomical Tide (LAT) -1.88 -2.07
Lowest Observed (12/171933)* -2.87 -3.06
The La Jolla tidal station also provides data on extreme water levels. Table 1-2 presents the extreme
water levels for 1, 2, 10 and 100 year return periods.
Table 1-2. Extreme Water Levels for La Jolla (Station 9410230)
Annual Exceedance Probability Levels Return Period (years) Elevation (ft, NAVD88)
1% 100 7.43
10% 10 7.20
50% 2 6.94
99% 1 6.51
1.1.2 Wind
The La Jolla station identified previously has also been measuring wind continuously since April 2009.
A review of this 11-year data record has revealed the predominant wind direction to be northwest with
wind speeds of 3 to 10 mph (Figure 1-2). Wind speeds greater than 10mph are most frequently out of
the WSW to the NW. [Q]owoo wowoMeanSeaLevel(MSL)2.73
NAVD88 0.19
Mean Low Water (MLW)0.90
Mean Lower Low Water (MLLW)0.00
Lowest Astronomical Tide (LAT)-1.88
Lowest Observed (12/1 71933)*-2.87
2.54
0.00
0.71
-0.19
-2.07
-3.06
The La Jolla tidal station also provides data on extreme water levels.Table 1-2 presents the extreme
water levels for 1,2,10 and 100 year return periods.
Table 1-2.Extreme Water Levels for La Jolla (Station 9410230)
Annual Exceedance Return Period (years)
Probability Levels
1 %100
10%10
50%2
99%1
1.1.2 Wind
Elevation (ft,
NAVD88)
7.43
7.20
6.94
6.51
The La Jolla station identified previously has also been measuring wind continuously since April 2009.
A review of this 11-year data record has revealed the predominant wind direction to be northwest with
wind speeds of 3 to 10 mph (Figure 1-2).Wind speeds greater than 10mph are most frequently out of
the WSW to the NW.
Jan. 4, 2022 Item 4 Page 96 of 229
Figure 1-1. Wind Rose for Station 9410230, La Jolla. (NOAA CO-OPS, 2020)
1.1.3 Waves
Oblique waves are the primary mechanism of longshore sediment transport along the Oceanside
shoreline. It is important to quantify the wave height, wave period and wave direction relative to the
shoreline. Consideration of seasonal variability is also essential. Wave data from two different sources
have been analyzed:
1. The USACE provides high quality wave hindcast data along United States coastlines via the
Wave Information Studies (WIS) project (USACE, 2020). The wave climate is predicted using
observed wind fields and spectral wave models to provide hourly, long-term wind and wave
data. Station 83105 is located offshore of the Project Area at a water depth of 824m (2,700ft)
and the results are provided based on a 32-year wave hindcast (1980 – 2011). A wave rose
is presented in Figure 1-4, and extreme value analysis identifying design wave heights for
various return periods in Figure 1-5. Based on this figure, the 100-year design offshore wave
height is approximately 22.5ft.
2. The Coastal Data Information Program (CDIP) maintains a wave buoy offshore of Oceanside.
Station 045 is located at a water depth of 238m (780ft) and provides a continuous measured
dataset from May 1997 through to present day. An extreme value analysis is presented in
Figure 1-6, and indicates the 100 year design offshore wave height is in excess of 19ft. A
wave rose is also presented in Figure 1-7.
The locations of both data sources is presented in Figure 1-3.
The most notable difference between the two sources is the wave direction. Both wave roses in Figure
1-4 and Figure 1-7 indicate larger wave heights are from the west; however, the direction with highest
frequency of occurrence differs. The WIS data suggests westerly waves occur most frequently while
the CDIP buoy measured southerly waves most often. It is recommended more value be placed on
WIND SPEED (MPH)
FREQUENCY_>200
—150-200
100-150
70-100
50-70
30-50
10-30WINDDIRECTIONV
If 9410230 La Jolla,CA CALM oss.(%):7.61
_01/01/09 01:00 GMT 29/07/20 23:00 GMT MISSING 033 (%):11_37
mommaDatasource:maSateUniversity;maEmlmnmemalMesona:CA_ASOS;CARLSBADIFALOMAR[ORG].NEW on:20200730.
Figure 1-1.Wind Rose for Station 9410230,La Jolla.(NOAA CO-OPS,2020)
1.1.3 Waves
Oblique waves are the primary mechanism of longshore sediment transport along the Oceanside
shoreline.It is important to quantify the wave height,wave period and wave direction relative to the
shoreline.Consideration of seasonal variability is also essential.Wave data from two different sources
have been analyzed:
1.The USACE provides high quality wave hindcast data along United States coastlines via the
Wave Information Studies (WIS)project (USACE,2020).The wave climate is predicted using
observed wind fields and spectral wave models to provide hourly,long-term wind and wave
data.Station 83105 is located offshore of the Project Area at a water depth of 824m (2,700ft)
and the results are provided based on a 32-year wave hindcast (1980 —2011).A wave rose
is presented in Figure 1-4,and extreme value analysis identifying design wave heights for
various return periods in Figure 1-5.Based on this figure,the 100-year design offshore wave
height is approximately 22.5ft.
The Coastal Data Information Program (CDIP)maintains a wave buoy offshore of Oceanside.
Station 045 is located at a water depth of 238m (780ft)and provides a continuous measured
dataset from May 1997 through to present day.An extreme value analysis is presented in
Figure 1-6,and indicates the 100 year design offshore wave height is in excess of 19ft.A
wave rose is also presented in Figure 1-7.
The locations of both data sources is presented in Figure 1-3.
The most notable difference between the two sources is the wave direction.Both wave roses in Figure
1-4 and Figure 1-7 indicate larger wave heights are from the west;however,the direction with highest
frequency of occurrence differs.The WIS data suggests westerly waves occur most frequently while
the CDIP buoy measured southerly waves most often.It is recommended more value be placed on
Jan. 4, 2022 Item 4 Page 97 of 229
the CDIP data given this is a real-time measured dataset, as opposed to a hindcast prediction, and is
determined at a location closer to the project shoreline.
The effect of seasonality and wave climate has been explored further via the preparation of wave
roses for various criteria on the CDIP data from 2000 to 2020. Common trends evident include:
• Large, mid to long period waves occur from the west during winter and early spring
• Small, long period waves occur from the south throughout the year but particularly in fall,
summer and spring
• Short period waves occur almost exclusively from the west
Additional information is presented in Section 2.3.3.
Figure 1-2. Wave Data Locations
[Q]E
the CDIP data given this is a real-time measured dataset,as opposed to a hindcast prediction,and is
determined at a location closer to the project shoreline.
The effect of seasonality and wave climate has been explored further via the preparation of wave
roses for various criteria on the CDIP data from 2000 to 2020.Common trends evident include:
0 Large,mid to long period waves occur from the west during winter and early spring
0 Small,long period waves occur from the south throughout the year but particularly in fall,
summer and spring
0 Short period waves occur almost exclusively from the west
Additional information is presented in Section 2.3.3.
Legend
.WIS Sta.33105
E Offshore OceanSide (0451
—Prejecl Shoreline
MIIBS
Mapiacticn:MeruuAuxnizy3pmHumml:wasISMcommune/stun:was1wwmuemmiaysmem Manama Uzmm
Figure 1-2.Wave Data Locations
Jan. 4, 2022 Item 4 Page 98 of 229
Figure 1-3. Wave Rose for WIS Station 83105 (1980-2011) [Q]w Pacific WIS Station 83105M01-Jan-1980 thru 31-Dec-2011“$5.!Long:-117.s7°Lat:33.oa°Depth2824111TotalOh:I 280511
WAVE ROSE
SIG WAVE HEIGHT (m)S
2-:u 4.5 5.1.561‘4 _
Figure 1-3.Wave Rose for WIS Station 83105 (1980-2011)
Jan. 4, 2022 Item 4 Page 99 of 229
Figure 1-4. Extreme Wave Analysis 1980-2011 (WIS Station 83105)
Figure 1-5. Extreme Wave Analysis 1998-2019 (CDIP Station 045) (CFC, 2019)
[Q]Figure 1-5.Extreme Wave Analysis 1998-2019 (CDIP Station 045)(CFC,2019)
’1 .q W Storm Event Return Period of 32-yr(1980-201 1 )Wave HindcastUml,5 E Pacific Station 83105 :Lat:33.0w Lam-117.670"Depth:824mw......r.............dr..Linear Fit to 10p 32 events:Hm =3.2187 +0.79038 -In [Retum Pariod(yrs)]
8 !!! I I !I !!!! ! !!!I ! !
EVOEIx ...V .m .... .
E 0 EventEFit9ate50-yr .2L”ate 100-yr
—--------Extrap
10‘1 10°to1 102
Return Period (yrs)
Top 10 events basedon Peak HmEventDaerrimewTC)Hm Tp 9......Event Deterrimeturct Hm Tp 9......
1 1933/01/13 13:00 6.30 16.29 273.0 6 1995/01/05 07:00 4.23 9.26 253.021933/03/02 07:00 5.71 19.13 241.0 1‘1932/12/01 02:00 4.20 9.91I 274.032010/01/22 01:00 5.00 9.90 224.0 3 1993/02/03 16:00 L16 9.20 221.0
1 1936/02/16 00:00 4.50 13.93 262.0 9 1930/02/20 06:00 4.01 16.32 25?.0
5 1935/03/03 03:00 4.36 9.33 236.0 10 2010/12/30 03:00 3.93 9.35 231.0
An event isdefined as anyperiod when Hm>2.00m arm“is directionthat waves arearriving from
m us Army EngineerResearch a DevetopmentCenter ST83105_V01
Figure 1-4.Extreme Wave Analysis 1980-201 1 (WIS Station 831 05)
24 I I |I ||
0 Observed
22 _""Predic‘ted _
20 -,,I,I _
18 '9"’’_
A V,E 16 ”I,a O fIor
I 0'”_,d E146,0
00065
12 ——
1D -—
8 O l l l I l ||
1 2 5 1D 20 50 100 200
Return Period (yrs)
Jan. 4, 2022 Item 4 Page 100 of 229
Figure 1-6. Wave Rose for CDIP Station 045 (2000-2020)
1.1.4 Currents
According to the USACE Hydraulic Model Study (WES, 1980; USACE, 1989), wave-induced current
patterns were determined at Oceanside Harbor with the use of dye tracers. It was found that northwest
and west swell produced southerly longshore currents along the north breakwater, harbor entrance
and past the San Luis Rey river groin (aka South Jetty) (Figure 1-8). Waves approaching from the
southwest produced northerly longshore currents along the seaward end of the north breakwater. The
mean seasonal offshore current velocities are estimated to range from 5 cm/s to 40 cm/s and
variations due to tidal influx are estimated to have peak current velocities of 20 cm/s (USACE, 1994).
Note that only moderate wave heights (i.e. 10-foot) with short periods (i.e. < 9 sec) were analyzed in
this study.
Hs (ft!
FREQUENCY __>201]
’3‘10.0 -20.0E:g 5.0 -10.0
2E 4.0 -5.0
a 3.0 -4.0
Ea 2.0 -3.0
B 1.0 -2.04
Figure 1-6.Wave Rose for CDIP Station 045 (2000-2020)
1.1.4 Currents
According to the USACE Hydraulic Model Study (WES,1980;USACE,1989),wave-induced current
patterns were determined at Oceanside Harbor with the use of dye tracers.It was found that northwest
and west swell produced southerly longshore currents along the north breakwater,harbor entrance
and past the San Luis Rey river groin (aka South Jetty)(Figure 1-8).Waves approaching from the
southwest produced northerly longshore currents along the seaward end of the north breakwater.The
mean seasonal offshore current velocities are estimated to range from 5 cm/s to 40 cm/s and
variations due to tidal influx are estimated to have peak current velocities of 20 cm/s (USACE,1994).
Note that only moderate wave heights (i.e.10-foot)with short periods (i.e.<9 sec)were analyzed in
this study.
Jan. 4, 2022 Item 4 Page 101 of 229
Figure 1-7. Wave-Induced Current Patterns (WES, 1980; USACE, 1989)
1.2 Elevation Data
1.2.1 Bathymetry
A number of publicly available elevation data sets are available for Oceanside and were utilized for
this study. The elevation data downloaded is listed in Table 1-3. It should be noted that datasets have
spatial coverage limitations and vary in resolution. @re)DEEPWATER WAVE CHARACT RlS‘l’l
III-9 "I on.TOO SEC.mom SOUTH
—.an ion.1’-1 SEC."OM NOMHWES'I'
mt:DIVORAULIC soon "I!“(mane!
Figure 1-7.Wave-Induced Current Patterns (WES,1980;USAGE,1989)
1 .2 Elevation Data
1 .2.1 Bathymetry
A number of publicly available elevation data sets are available for Oceanside and were utilized for
this study.The elevation data downloaded is listed in Table 1-3.It should be noted that datasets have
spatial coverage limitations and vary in resolution.
Jan. 4, 2022 Item 4 Page 102 of 229
Table 1-3. List of Bathymetric Data Sources
No. Name / Source Notes (spatial coverage, resolution) Date of Survey
1 2016 USGS CoNED Topobathymetric Model (1930-2014)
Dataset extends offshore to 2,847 meters
1-meter spatial resolution
03/03/1930 to 12/31/2014
2 2016 USGS Lidar DEM Coverage extends 400 to 500 ft offshore. 04/28/2016 to 05/28/2016
3 2014 USACE NCMP Topobathy Lidar 1-meter grid resolution 09/08/2014 to 10/05/2014
4 2014 USCAE NCMP Topobathy Lidar DEM Dataset extends offshore approx. 1000 meters 09/08/2014 to 10/05/2014
1.2.2 Topography
The most recent publicly available topographic data for Oceanside is listed in Table 1-4. It should be
noted that datasets have spatial coverage limitations and vary in resolution.
Table 1-4. List of Topographic Data Sources
No. Name / Source Notes (spatial coverage, resolution) Date of Survey
1 2016 USGS Lidar
Coverage extends approximately to the high tide line.
0.35 meter spatial resolution
04/28/2016 to
05/28/2016
2 2016 USGS Lidar DEM Coverage extends 400 to 500 ft offshore. 04/28/2016 to 05/28/2016
3 2016 USGS CoNED Topobathymetric Model (1930-2014)
-Dataset extends offshore to 2,847 meters
-1-meter spatial resolution
03/03/1930 to 12/31/2014
4 2014 USACE NCMP Topobathy Lidar 1-meter grid resolution 09/08/2014 to 10/05/2014
5 2014 USCAE NCMP Topobathy Lidar DEM Dataset extends offshore approx. 1,000 meters 09/08/2014 to 10/05/2014
1.3 Sediment Transport
1.3.1 Sediment grain size characteristics
Oceanside’s shoreline was characterized in a Sampling Analysis Plan Results Report (SAPR)
prepared for the USACE (M&N 2016). The reaches used in this analysis are presented in Figure 1-9
and the results are summarized in Table 1-6. All sediment samples were described as a poorly graded
sand and silty sand. The coarsest sediment was found in sub-aerial samples while the finest sediment
appear to be located offshore and in close proximity to the harbor entrance. [6]Table 1-3.List of Bathymetric Data Sources
Name /Source Notes (spatial coverage’Date of Surveyresolution)
2016 USGS CoNED Dataset extends offshore to
Topobathymetric Model 2 847 meters 033,233,118?:0
(1930-2014)1-meter spatial resolution
.Coverage extends 400 to 500 ft 04/28/2016 to22016USGSL'dar DEM offshore.05/28/2016
3 2014 USACE NCMP 1-meter rid resolution 09/08/2014 to
Topobathy Lidar g 10/05/2014
2014 USCAE NCMP Dataset extends offshore 09/08/2014 to
Topobathy Lidar DEM approx.1000 meters 10/05/2014
1.2.2 Topography
The most recent publicly available topographic data for Oceanside is listed in Table 1-4.It should be
noted that datasets have spatial coverage limitations and vary in resolution.
Table 1-4.List of Topographic Data Sources
Notes (spatial coverage,resolution)Date of Survey
Coverage extends approximately to the high12016usesLidartideline.(34/28/2016 to..05/28/20160.35 meter spatial resolution
.04/28/2016 to22016USGSLIdarDEMCoverageextends400to500ftoffshore.05/28/2016
2016 USGS CoNED3TopobathymetricModel -Dataset extends offshore to 2,847 meters 03/03/1930 to
(1930_2014)-1-meter spatial resolution 12/31/2014
4 2014 USACE NCMP 1-meter rid resolution 09/08/2014 to
Topobathy Lidar 9 10/05/2014
5 2014 USCAE NCMP Dataset extends offshore approx.1,000 09/08/2014 to
Topobathy Lidar DEM meters 10/05/2014
1 .3 Sediment Transport
1.3.1 Sediment graiEze characteristics
Oceanside’s shoreline was characterized in a Sampling Analysis Plan Results Report (SAPR)
prepared for the USACE (M&N 2016).The reaches used in this analysis are presented in Figure 1-9
and the results are summarized in Table 1-6.All sediment samples were described as a poorly graded
sand and silty sand.The coarsest sediment was found in sub-aerial samples while the finest sediment
appear to be located offshore and in close proximity to the harbor entrance.
Jan. 4, 2022 Item 4 Page 103 of 229
Table 1-5. Oceanside Sediment Characteristics (M&N, 2016)
Reach
Sediment
Characteristics A B C D E F G Santa
Margarita
D50 Range (mm) 0.1 to
0.5
0.1 to
0.4
0.1 to
0.3
0.1 to
0.3
0.1 to
0.2
0.1 to
0.2
0.1 to
0.2 0.1 to 0.2
% Fines 0.6 to
54.7
0.7 to
64.2
0.4 to
67.6
0.4 to
73.3
0.7 to
79.6
1.2 to
53.9
1.4 to
78.9 1.0 to 77.7
Figure 1-8. 2016 SAPR Shoreline Reaches (M&N, 2016)
1.3.2 Offshore Sediment Resources
Vibracore samples were collected at locations offshore of Oceanside Harbor in 1999, as presented in
Figure 1-10, to determine whether the site was a viable offshore borrow area for a beach nourishment
project. The seabed surface and subsurface at offshore borrow site SO9 was found to have a 12”
sandy silt layer on the surface, followed by a 3’ to 23’ fine to medium grained sand layer, and a fine
grained silty sand layer below the sand layer. Additionally, a geophysical survey in 1999 revealed
eight quarry rock artificial reef habitats within site SO9 (Sea Surveyor, Inc., 1999). A cross section is
shown in Figure 1-11. [9]Table 1-5.Oceanside Sediment Characteristics (M&N,2016)
Sediment Santa
0.1 to 0.1 to 0.1 to 0.1 to 0.1 to 0.1 to 0.1 toD5"Range (mm)0.5 0.4 0.3 0.3 0.2 0.2 0.2 0'1 to 0'2
0.6to O.7to 0.4to O.4to 0.7to 1.2to 1.4to “”0777
54.7 64.2 67.6 73.3 79.6 53.9 78.9 ''%Fines
Study Reaches
Roacrm
”each6
new"c
ReachD
.ReachEX“I 'V 'V R "V RoachF
‘19t
t,”502.500 5300 marl-mm”;.——_Fee-I--unm-I-n-nuns.«mm-um.Mmhnfi‘Hm—qufi-fll—h.“
Figure 1-8.2016 SAPR Shoreline Reaches (M&N,2016)
1.3.2 Offshore Sediment Resources
Vibracore samples were collected at locations offshore of Oceanside Harbor in 1999,as presented in
Figure 1-10,to determine whether the site was a viable offshore borrow area for a beach nourishment
project.The seabed surface and subsurface at offshore borrow site 809 was found to have a 12”
sandy silt layer on the surface,followed by a 3’to 23’fine to medium grained sand layer,and a fine
grained silty sand layer below the sand layer.Additionally,a geophysical survey in 1999 revealed
eight quarry rock artificial reef habitats within site 809 (Sea Surveyor,Inc.,1999).A cross section is
shown in Figure 1-11.
Jan. 4, 2022 Item 4 Page 104 of 229
To the immediate south, offshore borrow site SO8 was found to have a surficial silty fine grained sand
layer that ranged from 4’-13’ thick, followed by a fine grained sand that was 6’-25’ thick. Four piles of
artificial reef remains were found on the seafloor at this site. A cross section is shown in Figure 1-12.
Figure 1-9. Vibracore Sampling in Oceanside (M&N, 2016; USACE, 2011)
Figure 1-10. Typical Cross Section at Site SO9 (Sea Surveyor, Inc., 1999)
[Q]To the immediate south,offshore borrow site 808 was found to have a surficial silty fine grained sand
layer that ranged from 4’-13’thick,followed by a fine grained sand that was 6’-25’thick.Four piles of
artificial.reeiremains__w_e_re__f_ound__or_1_theseafloor..at__this._.site,._A__cr_o_s_s___s_ection_is__shown__in._Ei_<1ur_e___1_:12.
a .7 .a .5 Ms t .J 2 I
K
'anmCCEANSIDF
E
mowsir:Mo. 2Vim!flu:Locmous-LEiIJIr
SIG-J‘taunt-”Immun-
-1°3 m:mammnumun
"F7I mammalian-um
0"0 mm»mmm mm:
Figure 1-9.Vibracore Sampling in Oceanside (M&N,2016;USAGE,2011)
DEPTH (MLLW)SITE 50-9.SURVEY LINE 2W.
—MIMI:SILT LAYER
”-—
"'—_a g-SAND LAYER .w —ES mmww wmwwaagm
_5;WWI-E WP VIEW LODKNG usr 20x VERT.EKAGG.""IIIllllllllllllllllllllllllllll
0'1000'zm'm
DISTANCE FROM NORTHERN SITE WNW
Figure 1-10.Typical Cross Section at Site SO9 (Sea Surveyor,Inc.,1999)
Jan. 4, 2022 Item 4 Page 105 of 229
Figure 1-11. Typical Cross Section at Site SO8 (Sea Surveyor, Inc., 1999)
1.3.3 Longshore Transport
The net longshore currents for Oceanside are understood to be southern, although seasonal variations
are common and depend on the swell direction. During the summer, long period swells directed from
the south produce a northern current. Northwesterly swells in the winter produce southern currents.
The gross southern transport typically exceeds the northern transport on an annual basis. There are
numerous estimates of the longshore sediment transport for the City and within the Oceanside littoral
cell, as shown in Table 1-7. There is general agreement amongst the sources provided that Oceanside
experiences a net sediment transport to the south of 100,000 to 200,000 cubic yards (cy) per year.
Table 1-6. Longshore Sediment Transport Estimates in the City
Location
Estimated Gross
Northern Transport
Rate (cy/yr)
Estimated
Gross
Southern
Transport
Rate
(cy/yr)
Estimated Net
Southerly
Longshore
Transport Rate
(cy/yr)
Source
Oceanside
Littoral Cell
545,000 760,000 215,000 Marine Advisors
(1961)
NA NA 250,000 Inman (1976)
550,000 740,000 194,000
Hales (1979); Inman &
Jenkins (1985); Dolan
et al. (1987)
Oceanside
Harbor
Southside
934,000 106,000
USACE, (1991);
Tekmarine, Inc.,
(1978)
Oceanside NA NA 146,000 Patsch & Griggs, 2006
Oceanside 553,000 807,000 254,000 Inman & Jenkins
(1983) [Q]03W (MLLVIJ SITE 80-8.SURVEY LINE 5
W ——:SILT LAYER :—I “MI:IW—_:“Sig—egg:599'”_,_:.u-_SEN-100R --------'
m-__
u,-__
g-__
'"I __SAND um:gm'—Sediment layer:dotsrmined from Im'__§§salami:reflectlon and vlhmcora lags:._a,V“LOOKING NORTH 10:VEFIT.EXAGGHm|l'lrl'l'l'I'l'l'I'l'l'l'l'l'l'l1m
“wfiflflfil‘w DISTANCE FROM WESTERN SITE BWHDARY
strum:sum
Figure 1-11.Typical Cross Section at Site 808 (Sea Surveyor,Inc.,1999)
1.3.3 Longshore Transport
The net longshore currents for Oceanside are understood to be southern,although seasonal variations
are common and depend on the swell direction.During the summer,long period swells directed from
the south produce a northern current.Northwesterly swells in the winter produce southern currents.
The gross southern transport typically exceeds the northern transport on an annual basis.There are
numerous estimates of the longshore sediment transport for the City and within the Oceanside littoral
cell,as shown in Table 1-7.There is general agreement amongst the sources provided that Oceanside
experiences a net sediment transport to the south of 100,000 to 200,000 cubic yards (cy)per year.
Table 1-6.Longshore Sediment Transport Estimates in the City
Estimated Gross Estimated
Northern Transport Gross
Rate (cy/yr)Southern
Transport
Rate
(Cy/yr)
Estimated Net
Southerly
Longshore
Transport Rate
(Cy/yr)
545,000
7
6
0
,
0
0
0
215,000 Marine Advrsors
(1961)
Oceanside NA NA 250,000 Inman (1976)
Littoral Ce”Hales (1979);Inman &
550,000 740,000 194,000 Jenkins (1985);Dolan
et al.(1987)
Oceanside USACE,(1991);
Harbor 934,000 106,000 Tekmarine,|nc.,
Southside (1978)
Oceanside NA NA 146,000 Patsch &Griggs,2006
Oceanside 553,000 807,000 254,000 '"man 8‘Jenkins(1983)
Jan. 4, 2022 Item 4 Page 106 of 229
Location
Estimated Gross Northern Transport
Rate (cy/yr)
Estimated Gross
Southern
Transport
Rate
(cy/yr)
Estimated Net
Southerly
Longshore
Transport Rate
(cy/yr)
Source
Oceanside 541,000 643,000 102,000 Hales (1978)
Oceanside NA NA 175,000 USACE, 2016
1.3.4 Cross Shore Transport
Cross-shore sediment transport within the Oceanside littoral cell is estimated to range from 26,000 to
113,000 cy/year (USACE, 1991). These currents predominantly exist during high energy storm events
and will most likely be concentrated at creek mouths and around structures USACE (1994).
It is also hypothesized that the Oceanside Harbor structure produces cross shore currents capable of
transporting sediment offshore (USACE, 1991). After construction of the harbor, an average of
146,000 cy/year to 440,000 cy/year was found to accumulate in the offshore vicinity of the harbor
(Tekmarine, 1987; USACE, 1991).
The closure depth (i.e. depth at which the bathymetry remains unchanged over time) for the Oceanside
shoreline provides insight to the range of sediment fluctuation between the nearshore and offshore
region. Estimates of closure depth from SANDAG’s Regional Beach Monitoring Program data set is
presented in Table 1-8 from seven beach profile transects within the City. These beach profile
transects are shown in Figure 1-13. The average depth of closure in the City is 22.4 feet below MLLW.
Table 1-7. Depth of Closure Estimates for Oceanside (Coastal Frontiers, 2019)
Beach Profile Transect Location Depth of Closure (ft, MLLW)
OS-0900 Saint Malo, Oceanside -24
OS-0915 Caissdy Street, Oceanside -22
OS-0930 Buccaneer Beach, Oceanside
-25
OS-0947 Crosswaithe -23
OS-1000 South Strand, Oceanside -21
OS-1030 North Strand, Oceanside -21
OS-1070 Oceanside Harbor Beach -21
Average - -22.4 [6]Estimated Gross Estimated
Northern Transport Gross Estimated Net
Rate (cy/yr)Southern SoutherlyLongshoreTransportTransportRateRate(cy/yr)
(Cy/yr)
Oceanside 541,000 643,000 102,000 Hales (1978)
Oceanside NA NA 175,000 USACE,2016
1.3.4 Cross Shore Transport
Cross-shore sediment transport within the Oceanside littoral cell is estimated to range from 26,000 to
113,000 cy/year (USACE,1991 ).These currents predominantly exist during high energy storm events
and will most likely be concentrated at creek mouths and around structures USEF (1994).
It is also hypothesized that the Oceanside Harbor structure produces cross shore currents capable of
transporting sediment offshore (USACE,1991).After construction of the harbor,an average of
146,000 cy/year to 440,000 cy/year was found to accumulate in the offshore vicinity of the harbor
(Tekmarine,1987;USACE,1991).
The closure depth (i.e.depth at which the bathymetry remains unchanged over time)for the Oceanside
shoreline provides insight to the range of sediment fluctuation between the nearshore and offshore
region.Estimates of closure depth from SANDAG’s Regional Beach Monitoring Program data set is
presented in Table 1-8 from seven beach profile transects within the City.These beach profile
transects are shown in Figure .The average depth of closure in the City is 22.4 feet below MLLW.
Table 1-7.Depth of Closure Estimates for Oceanside (Coastal Frontiers,2019)
Beach Profile Location Depth of Closure
Transect (ft,MLLW)
OS-0900 Saint Malo,-24
Oceansrde
OS-0915 Calssdy Street,-22
Oceansrde
Buccaneer -25
08-0930 Beach,
Oceanside
OS-0947 Crosswaithe -23
08-1000 South Strand,-21
Oceansrde
OS-1030 North Strand,-21
Oceansrde
OS-1070 Oceansrde -21
Harbor Beach
Average --22.4
Jan. 4, 2022 Item 4 Page 107 of 229
Figure 1-12. Regional Beach Monitoring Program Transect Locations
2. Literature Review
2.1 Existing Studies
2.1.1 USACE Sand Diego Coastal Storm and Tidal Waves Study (1991)
This study defines the oceanographic, geological and economic factors that have affected the beaches
within the San Diego region. In regards to the Oceanside sub-reach, this study defines three events
that have affected the shoreline during the study period. The first event is the construction of the harbor
which began in 1942 and was completed in 1963, in which an erosion rate of 4 ft/year was observed
along beaches south of the harbor following construction. The second event covers the nourishment
projects from 1960 to 1980, where beaches south of the Oceanside harbor displayed patterns of
accretion. The volumes of sand placed were large and regular, often in the order of hundreds of
thousands of cy annually, although there was one large event in 1963 where approximately 3.8 million
Legend
DApproximate RBSP l|BeachFill
_CFC 2012 Profiles
000 Yplaced ,720m ZOIL
ll ,7’h .Dec 71h,1\1l2
I]015 D3 045 0S_:—:IMilesvarnm,mmcmvmlcmNaurummmun-nan!ww‘mswmwmmm mmmmwwmmm firm:
Figure 1-12.Regional Beach Monitoring Program Transect Locations
Literature Review
2.1 Existing Studies
2.1.1 USACE Sand Diego Coastal Storm and Tidal Waves Study (1991)
This study defines the oceanographic,geological and economic factors that have affected the beaches
within the San Diego region.In regards to the Oceanside sub-reach,this study defines three events
that have affected the shoreline during the study period.The first event is the construction of the harbor
which began in 1942 and was completed in 1963,in which an erosion rate of 4 ft/year was observed
along beaches south of the harbor following construction.The second event CES the nourishment
projects from 1960 to 1980,where beaches south of the Oceanside harbor _'played patterns of
accretion.The volumes of sand placed were large and regular,often in the order of hundreds of
thousands of cy annually,although there was one large event in 1963 where approximately 3.8 million
Jan. 4, 2022 Item 4 Page 108 of 229
cy were placed on Oceanside. The third event relates to storms between 1978 and 1988. During this
time, beaches in Oceanside displayed erosion rates ranging from 4ft/year to 33 ft/year. The shoreline
change for all three events is shown in Figure 2-1.
Figure 2-1. Shoreline Change for the Oceanside Littoral Cell (USACE, 1991)
2.1.2 USACE Oceanside Shoreline Feasibility Study (2016 - ongoing)
The purpose of this study was to evaluate and characterize the coastal processes along Oceanside’s
beaches while also investigating possible erosion mitigation actions/projects. The study area was
divided into eight reaches, from the northern tip of the Oceanside Harbor to the Agua Hedionda
Lagoon (Figure 2-2). Shown in Figure 2-3, the beach north of the harbor remains relatively stable and
the beaches south of the harbor display high rates of erosion. Accretion is evident adjacent to both [Q]cy were placed on Oceanside.The third event relates to storms between 1978 and 1988.During this
time,beaches in Oceanside displayed erosion rates ranging from 4ft/year to 33 ft/year.The shoreline
change for all three events is shown in Figure 2—1.
OCEANSIDE LITTORAL CELL 'if”)RATE OF SHORELINE MOVEMENT
m-Emm ma-“5
Figure 2-1.Shoreline Change for the Oceanside Littoral Cell (USAGE,1991)
2.1.2 USACE Oceanside Shoreline Feasibility Study (2016 -ongoing)
The purpose of this study was to evaluate and characterize the coastal processes along Oceanside’s
beaches while also investigating possible erosion mitigation actions/projects.The study area was
divided into eight reaches,from the northern tip of the Oceanside Harbor to the Agua Hedionda
Lagoon (Figure 2-2).Shown in Figure 2—3,the beach north of the harbor remains relatively stable and
the beaches south of the harbor display high rates of erosion.Accretion is evident adjacent to both
Jan. 4, 2022 Item 4 Page 109 of 229
the harbor structure and the San Luis Rey groin, giving further evidence to the bimodal nature of
longshore erosion at Oceanside.
Figure 2-2. Study Area (USACE, 2016)
Figure 2-3. Rate of Beach Change from 1934 to 1998 (USACE, 2016)
This study evaluated nine action alternatives that included managed retreat, flood proofing, beach
nourishment, revetment or seawall, groin field, harbor bypass, and use of O&M dredged material.
Some of these options would need to be implemented in conjunction with others to be effective. The
action alternatives evaluated in this study are provided in Table 2-1. [Q]the harbor structure and the San Luis Rey groin,giving further evidence to the bimodal nature of
longshore erosion at Oceanside.
SEAFH B
Figure 2-2.Study Area (USACE,2016)
SLRPierGroin "an”,
—Rate of Change1934to1998
ShorelineChangeRate(mlyr)0 10 20 30 40 50 60 70 80 90 100110120130140150160170180190 200 210 220 230 240
Model Cell Number
Figure 2-3.Rate of Beach Change from 1934 to 1998 (USACE,2016)
This study evaluated nine action alternatives that included managed retreat,flood proofing,beach
nourishment,revetment or seawall,groin field,harbor bypass,and use of 0&M dredged material.
Some of these options would need to be implemented in conjunction with others to be effective.The
action alternatives evaluated in this study are provided in Table 2-1.
Jan. 4, 2022 Item 4 Page 110 of 229
Table 2-1. Action Alternatives Analyzed in USACE 2016
Alternative Description
1 Beach Nourishment with Harbor Condition
2 Beach Nourishment with Managed Retreat
3 Beach Nourishment with Floodproofing
4 Beach Nourishment with Revetment
5 Beach Nourishment with Seawall
6 Beach Nourishment with Groins
7 Beach Nourishment with Harbor Bypass
8 Beach Nourishment with O&M Dredged Material
9 Beach Nourishment without Harbor Condition
These options were screened based on completeness, effectiveness, efficiency, and acceptability.
Completeness refers to the extent that an alternative provides, accounting for investments and actions
required to achieve the projects goals. Effectiveness is defined as the extent to which a plan achieves
its objectives. Efficiency refers to the provided net benefits and acceptability refers to an alternatives
alignment with federal law and policy. It also considers real estate issues, operations, maintenance,
monitoring and sponsorship.
The preliminary screening process revealed the best alternative solutions to be Alternative 1: Beach
Nourishment with Harbor Condition, Alternative 6: Beach Nourishment with Groins and Alternative 9:
Beach Nourishment without Harbor Condition.
The next stages of this study are to further evaluate the final array of alternatives and then to select
and recommend a plan. This study is awaiting funding for completion.
2.1.3 USACE Oceanside Shoreline Reconnaissance Report (1994)
This study divides the shoreline of Oceanside in five (5) reaches for analysis (Figure 2-4). Reach 1
has shown patterns of accretion and stability in the past (1972 to 1989), possibly as a result of the
deposition from the San Luis Rey River Mouth and south groin. Reach 2 has been characterized as
erosional, about 3.5 feet per year from 1972 to 1989. Reach 3 displays very similar patterns of erosion
to that of reach 2, eroding 3 feet per year from 1972 to 1989. Reaches 4 and 5 displayed an erosion
rate of 2.5 and 2 feet per year; respectively.
The projected sediment budget for Oceanside is shown in Figure 3-5. The longshore transport rate is
estimated to be 270,000 cy/yr in a southerly direction. About 30 cy/yr is lost in the cross-shore direction
while the San Luis Rey River provides around 10,000 cy/yr of sediment to the system. Additionally,
100,000 to 200,000 cy/yr is deposited at the harbor entrance, which is dredged annually and
redistributed along the beach.
The predominant sediment sources for Oceanside include the San Luis Rey River, sediment
transported from north of the Harbor, and dredging of the harbor entrance. The sediment sinks include
sand deposited within the harbor, sand lost to the south, and sand lost offshore. The net sand volume
change in the City has been estimated to be a loss of 90,000 cy/yr. [9]Table 2-1.Action Alternatives Analyzed in USACE 2016
Alternative1 Beach Nourishment with Harbor Condition
Beach Nourishment with Managed Retreat
Beach Nourishment with Floodproofing
Beach Nourishment with Revetment
Beach Nourishment with Seawall
Beach Nourishment with Groins
Beach Nourishment with Harbor Bypass
Beach Nourishment with O&M Dredged Material
Beach Nourishment without Harbor Condition(OGJNQU'l-POONThese options were screened based on compleEss,effectiveness,efficiency,and acceptability.
Completeness refers to the extent that an alternati _rovides,accounting for investments and actions
required to achieve the projects goals.Effectiveness is defined as the extent to which a plan achieves
its objectives.Efficiency refers to the provided net benefits and acceptability refers to an alternatives
alignment with federal law and policy.It also considers real estate issues,operations,maintenance,
monitoring and sponsorship.
The preliminary screening process revealed the best alternative solutions to be Alternative 1:Beach
Nourishment with Harbor Condition,Alternative 6:Beach Nourishment with Groins and Alternative 9:
Beach Nourishment without Harbor Condition.
The next stages of this study are to further evaluate the final array of alternatives and then to select
and recommend a plan.This study is awaiting funding for completion.
2.1.3 USACE Oceanside Shoreline Reconnaissance Report (1994)
This study divides the shoreline of Oceanside in five (5)reaches for analysis (Figure 2—4).Reach 1
has shown patterns of accretion and stability in the past (1972 to 1989),possibly as a result of the
deposition from the San Luis Rey River Mouth and south groin.Reach 2 has been characterized as
erosional,about 3.5 feet per year from 1972 to 1989.Reach 3 displays very similar patterns of erosion
to that of reach 2,eroding 3 feet per year from 1972 to 1989.Reaches 4 and 5 displayed an erosion
rate of 2.5 and 2 feet per year;respectively.
The projected sediment budget for Oceanside is shown in Figure 3-5.The longshore transport rate is
estimated to be 270,000 cy/yr in a southerly direction.About 30 cy/yr is lost in the cross-shore direction
while the San Luis Rey River provides around 10,000 cy/yr of sediment to the system.Additionally,
100,000 to 200,000 cy/yr is deposited at the harbor entrance,which is dredged annually and
redistributed along the beach.
The predominant sediment sources for Oceanside include the San Luis Rey River,sediment
transported from north of the Harbor,and dredging of the harbor entrance.The sediment sinks include
sand deposited within the harbor,sand lost to the south,and sand lost offshore.The net sand volume
change in the City has been estimated to be a loss of 90,000 cy/yr.
Jan. 4, 2022 Item 4 Page 111 of 229
Figure 2-4. Defined Study Reaches (USACE, 1994)
g ma».
Wsrar3LagoonESanDie0Freeway
‘1...“5 Oceanside as 5‘a _i 3L=a 3 a gEcgTcHm518>The Strand g §5 Pacific s:-has as;.‘:Stualo':mo woo.nosoao assua-91h StBeach1 Reach?\Fleach .Beach 4 Beach 5MunlclplaPier
l__2,fl)_n'__|Pacific Ocean
Figure 2-4.Defined Study Reaches (USAGE,1994)
Jan. 4, 2022 Item 4 Page 112 of 229
Figure 2-5. Projected Sediment Budget for Oceanside (USACE, 1994)
[Q]Oceanside
270 ’
LEGEND
Grange inmom:SedimentVolume(000's yalyr)
Sediment Flux Rate{000's ram
,--.,_Harba '200 r Dredgmg
-——p270
'WithOUt Project Sediment Budget '[000's y3lyr}
Salim Sinks
Nomiern Boundary:100 —1oo Northern Transport into HarborHarborDredging:200 -270 Net Southern TransportSLR.River 10 —3D Offshore Losses
Total:3'10 400 Tatar
NET VOLUME CHANGE =—90
Figure 2-5.Projected Sediment Budget for Oceanside (USAGE,1994)
Jan. 4, 2022 Item 4 Page 113 of 229
2.1.4 City of Oceanside Sea Level Rise Vulnerability Assessment & Adaptation Plan (2018)
The City of Oceanside assessed its coastal assets using four sea level rise (SLR) scenarios:
• 0.8ft by 2025-2045
• 1.6ft by 2040-2070
• 3.3ft by 2070-2100
• 5.7ft by 2100-2140
Five potential hazard zones were mapped, with the following outcomes observed:
(1) Potential ocean water levels with beach erosion – predominantly affecting the low-lying
areas adjacent to the San Luis Rey River, Loma Alta Creek, and the Buena Vista Lagoon.
(2) Potential coastal flooding and waves – predicted to impact the infrastructure and coastline
nearest to the San Luis Rey River mouth and the Loma Alta Creek river mouth.
(3) Potential coastal and riverine flooding – predominantly affecting the low-lying areas
adjacent to the San Luis Rey River, Loma Alta Creek, and the Buena Vista Lagoon.
(4) Potential coastal flooding wave runup – predicted to impact the coastline and infrastructure
on the western side of the railroad and north of the Buena Vista Lagoon, as well as the
Strand south of the pier and coastline south of Oceanside Harbor. In addition, over-flooding
of wetlands could lead to mudflats and the loss of critical species habitats such as the
Coastal California Gnatcatcher, Least Bell’s Vireo and South-western Willow Flycatcher.
(5) Potential development erosion – The Small Craft Harbor and 15 recreational buildings that
are in close proximity to the harbor are expected to experience more regular flooding. The
Oceanside harbor, jetties and breakwater, and pier may experience flooding along with
increased erosion of the structures. The homes clustered around the Buena Vista Creek
and the Oceanside harbor are most at risk to the effects of SLR.
2.1.5 San Diego Regional Beach Sand Monitoring Program (CFC, 2019)
SANDAG began the Regional Shoreline Monitoring Program in 1996 to measure the changes in beach
width over time and document the sand replenishment projects in San Diego. Beach profile data is
collected biannually along the coastline of San Diego County. The monitoring program data was
valuable for the design of the RBSP I and II projects (SANDAG, 2019).
As can be seen in Figure 2-6, the 2020 beach width and shorezone volume for Oceanside has dropped
below the post-RBSP I and II levels. From 2000 to 2020, the average shorezone volume displays a
net loss of sediment for the region.
[Q]2.1.4 City of Oceanside Sea Level Rise Vulnerability Assessment &Adaptation Plan (2018)
The City of Oceanside assessed its coastal assets using four sea level rise (SLR)scenarios:
0 0.8ft by 2025-2045
0 1.6ft by 2040-2070
0 3.3ft by 2070-2100
0 5.7ft by 2100-2140
Five potential hazard zones were mapped,with the following outcomes observed:
(1)
(2)
(3)
(4)
(5)
2.1.5
Potential ocean water levels with beach erosion —predominantly affecting the low-lying
areas adjacent to the San Luis Rey River,Loma Alta Creek,and the Buena Vista Lagoon.
Potential coastal flooding and waves —predicted to impact the infrastructure and coastline
nearest to the San Luis Rey River mouth and the Loma Alta Creek river mouth.
Potential coastal and riverine flooding —predominantly affecting the low-lying areas
adjacent to the San Luis Rey River,Loma Alta Creek,and the Buena Vista Lagoon.
Potential coastal flooding wave runup —predicted to impact the coastline and infrastructure
on the western side of the railroad and north of the Buena Vista Lagoon,as well as the
Strand south of the pier and coastline south of Oceanside Harbor.In addition,over-flooding
of wetlands could lead to mudflats and the loss of critical species habitats such as the
Coastal California Gnatcatcher,Least Bell’s Vireo and South-western Willow Flycatcher.
Potential develofint erosion gm Small Craft Harbor and 15 recreational buildings that
are in close prox to the hagare expected to experience more regular flooding.The
Oceanside harbor,jetties and breakwater,and pier may experience flooding along with
increased erosion of the structures.The homes clustered around the Buena Vista Creek
and the Oceanside harbor are most at risk to the effects of SLR.
San Diego Regional Beach Sand Monitoring Program (CFC,2019)
SANDAG began the Regional Shoreline Monitoring Program in 1996 to measure the changes in beach
width over time and document the sand replenishment projects in San Diego.Beach profile data is
collected biannually along the coastline of San Diego County.The monitoring program data was
valuable for the design of the RBSP |and II projects (SANDAG,2019).
As can be seen in Figure 2-6,the 2020 beach width and shorezone volume for Oceanside has dropped
below the post-RBSP |and II levels.From 2000 to 2020,the average shorezone volume displays a
net loss of sediment for the region.
Jan. 4, 2022 Item 4 Page 114 of 229
Figure 2-6. Average Beach Width and Shorezone Volume for Oceanside (CFC,
2020)
2.2 Prior Projects
2.2.1 Regional Beach Sand Projects I and II
In 2001, the RBSP I placed a total of 2 million cy of sand onto 12 beaches within San Diego County.
The majority of this beach fill sediment was placed among 10 beaches within the Oceanside littoral
cell. These 10 beaches received 1.8 million cy and Oceanside Beach alone received 421,000 cy. The
median grain size of the material placed in Oceanside was a coarse sand (0.62mm) (Coastal Frontiers,
2019; Noble Consultants, 2001).
In 2012, the RBSP II placed a total of 1.5 million cy of sand onto eight beaches in San Diego County.
Approximately 1 million cy was placed in the Oceanside littoral. Oceanside received 292,000 cy of
Fall 2012 Fall 2015
E
”3,,—mmmm-mun omuoefuo
*WVMM
.100
Amo.chlngoloumVWmhanIShuuum'32':.um .
2000 2001 2002 2003 2M 1005 2”2N7 2003 2009 2Y010 2011 2012 2013 2014 2015 2016 2017I 2018 2019 2020
It
Fall 2015Fall2012
Figure 2-6.Average Beach Width and Shorezone Volume for Oceanside (CFC,
2020)
2.2 Prior Projects
2.2.1 Regional Beach Sand Projects I and II
In 2001,the RBSP I placed a total of 2 million cy of sand onto 12 beaches within San Diego County.
The majority of this beach fill sediment was placed among 10 beaches within the Oceanside littoral
cell.These 10 beaches received 1.8 million cy and Oceanside Beach alone received 421,000 cy.The
median grain size ofthe material placed in Oceanside was a coarse sand (0.62mm)(Coastal Frontiers,
2019;Noble Consultants,2001).
In 2012,the RBSP ||placed a total of 1.5 million cy of sand onto eight beaches in San Diego County.
Approximately 1 million cy was placed in the Oceanside littoral.Oceanside received 292,000 cy of
Jan. 4, 2022 Item 4 Page 115 of 229
sand between Buccaneer Beach and Hayes Street. The median grain size of the sand placed in
Oceanside was a coarse sand (0.54mm) (Coastal Frontiers, 2019; Webb, 2013).
Since the RBSP I and II, the Oceanside shoreline has shown episodic periods of accretion but continue
to follow a pattern of erosion. By 2008, the average shoreline position had retreated below the Pre-
RBSP I shoreline levels. The RBSP II nourishment in 2012 increased the shoreline width and volume
to Pre-RBSP I conditions. However, the net accretion trend has continued and Oceanside currently
has a sediment deficit.
2.2.2 Buccaneer Beach Ocean Outfall
As part of the La Salina Wastewater ocean outfall pipeline construction, rock was placed shore-
perpendicular to protect the shallow pipeline at Buccaneer Beach. An aerial showing the extent of the
structure in 1971 is shown in Figure 2-7. In function and in design, the protective rock and pipeline
acted similar to a groin and offers site-specific empirical evidence of shoreline response. A small fillet
of sand is observed on the south side of the ocean outfall structure during an observed south swell.
Although a date of the image could not be confirmed, given the wave conditions, the aerial is presumed
to be taken during the south swell season of April-October. The emergent pipeline depicted was
replaced relatively quickly with a pipeline that went underground through the beach and surfzone and
emerged on the seafloor in the nearshore. [Q]sand between Buccaneer Beach and Hayes Street.The median grain size of the sand placed in
Oceanside was a coarse sand (0.54mm)(Coastal Frontiers,2019;Webb,2013).
Since the RBSP |and II,the Oceanside shoreline has shown episodic periods of accretion but continue
to follow a pattern of erosion.By 2008,the average shoreline position had retreated below the Pre-
RBSP |shoreline levels.The RBSP ||nourishment in 2012 increased the shoreline width and volume
to Pre-RBSP |conditions.However,the net accretion trend has continued and Oceanside currently
has a sediment deficit.
2.2.2 Buccaneer Beach Ocean Outfall
As part of the La Salina Wastewater ocean outfall pipeline construction,rock was placed shore-
perpendicular to protect the shallow pipeline at Buccaneer Beach.An aerial showing the extent of the
structure in 1971 is shown in Figure 2-7.In function and in design,the protective rock and pipeline
acted similar to a groin and offers site-specific empirical evidence of shoreline response.A small fillet
of sand is observed on the south side of the ocean outfall structure during an observed south swell.
Although a date of the image could not be confirmed,given the wave conditions,the aerial is presumed
to be taken during the south swell season of April-October.The emergent pipeline depicted was
replaced relatively quickly with a pipeline that went underground through the beach and surfzone and
emerged on the seafloor in the nearshore.
Jan. 4, 2022 Item 4 Page 116 of 229
Figure 2-7. Buccaneer Beach Rock Protected Ocean Outfall in 1971 (Moffatt and
Nichol, 2001)
2.2.3 Oceanside Harbor Experimental Sand Bypassing Pilot Project
Constructed in 1985 and operating from 1989 to 1992, the sand bypassing system utilized an array of
fixed jet pumps, fluidizers, and a portable jet pump system (Figure 2-8) (Moffatt and Nichol, 1982;
Boswood & Murray, 2001). The system was designed to pump 2,000-3,000 cy/day with a net discharge
of 350,000 cy annually (Moffatt and Nichol, 1982 USACE, 1996). Accounting for seasonal variations
in longshore sediment transport patterns, approximately 200,000 cy of sand was proposed to be
pumped from the channel entrance in the summer months and 150,000 cy of sand from the northern
fillet in the winter months (USACE, 1995; USACE, 1996).
This project ultimately had a multitude of issues revolving around maintenance of the pumps and
inadequate funding. With an estimated total cost of $5 million and an actual cost of $15 million, only
the first two phases of the project were completed (Boswood & Murray, 2001). Phase one consisted
of basic installations and phase two covered the installation of two crater fill fluidizers and two jet
pumps at the main channel entrance (USACE, 1996). The overall performance of the sand bypassing
system is summarized in Table 2-2. [Q]Figure 2-7.Buccaneer Beach Rock Protected Ocean Outfall in 1971 (Moffatt and
Nichol,2001)
2.2.3 Oceanside Harbor Experimental Sand Bypassing Pilot Project
Constructed in 1985 and operating from 1989 to 1992,the sand bypassing system utilized an array of
fixed jet pumps,fluidizers,and a portable jet pump system (Figure 2-8)(Moffatt and Nichol,1982;
Boswood &Murray,2001 ).The system was designed to pump 2,000-3,000 cy/day with a net discharge
of 350,000 cy annually (Moffatt and Nichol,1982 USACE,1996).Accounting for seasonal variations
in longshore sediment transport patterns,approximately 200,000 cy of sand was proposed to be
pumped from the channel entrance in the summer months and 150,000 cy of sand from the northern
fillet in the winter months (USACE,1995;USACE,1996).
This project ultimately had a multitude of issues revolving around maintenance of the pumps and
inadequate funding.With an estimated total cost of $5 million and an actual cost of $15 million,only
the first two phases of the project were completed (Boswood &Murray,2001).Phase one consisted
of basic installations and phase two covered the installation of two crater fill fluidizers and two jet
pumps at the main channel entrance (USACE,1996).The overall performance of the sand bypassing
system is summari'in Table 2-2.
Jan. 4, 2022 Item 4 Page 117 of 229
Figure 2-8. Experimental Bypass System Schematic (Moffatt & Nichol, 1982)
Table 2-2. Sand Bypassing Performance (Boswood & Murray, 2001)
Phase Date Total Operating Hours
System Downtime and Maintenance Hours
Averaged Bypassing Rate
Total
Bypassed
Phase I June 1989 to August 1990* 744 - 63 cy/hr ~18,300 cy
Phase II
December 1991 to December 1992 1,128 607 95 cy/hr 106,000 cy
*Excludes January 1990 to April 1990
2.3 Ongoing Projects and Programs
A summary of ongoing coastal management programs and projects were reviewed for potential
opportunities to integrate Project needs with ongoing efforts.
2.3.1 USACE Harbor Dredging Program
Sand is dredged annually from the Oceanside Harbor entrance channel via a cutterhead suction
dredge, transported south in a slurry via a pipe, and placed on City beaches. Dredged sediment is
discharged onto intertidal portions of the beach and dozers, located downdrift of the discharge, scrape
material up from the intertidal to the foreshore or dry beach (Figure 2-9). The gradation of the sediment
dredged from the harbor entrance for six years between 2012 and 2020 is shown in Table 2-3.
Samples taken at the placement sites revealed the dredged sediment to be mainly fine sands, with a
mean median grain size (D50) between 0.11 mm and 0.18 mm. Samples were classified predominantly
as poorly graded, silty-sand (Smith-Emery Laboratories, 2020). The specific sand placement locations
and volumes vary by year based on a variety of factors. The annual dredged sediment quantities from
1942 to 2021 for the Oceanside Harbor are shown in Table 2-4.
[6]OGEAAISIPE
Figure 2-8.Experimental Bypass System Schematic (Moffatt &Nichol,1982)
Table 2-2.Sand Bypassing Performance (Boswood &Murray,2001)
Total System Downtime Averaged Total
Phase Date Operating and Maintenance Bypassing B assed
Hours Hours Rate yp
Phase June 1989 to|August 1990*744 -63 cy/hr ~18,300 cy
Phase December 1991
to December 1,128 607 95 cy/hr 106,000 cy"1992
*Excludes January 1990 to April 1990
2.3 Ongoing Projects and Programs
A summary of ongoing coastal management programs and projects were reviewed for potential
opportunities to integrate Project needs with ongoing efforts.
2.3.1 USACE Harbor Dredging Program
Sand is dredged annually from the Oceanside Harbor entrance channel via a cutterhead suction
dredge,transported south in a slurry via a pipe,and placed on City beaches.Dredged sediment is
discharged onto intertidal portions of the beach and dozers,located downdrift of the discharge,scrape
material up from the intertidal to the foreshore or dry beach (Figure 2—9).The gradation of the sediment
dredged from the harbor entrance for six years between 2012 and 2020 is shown in Table 2—3.
Samples taken at the placement sites revealed the dredged sediment to be mainly fine sands,with a
mean median grain size (D50)between 0.11 mm and 0.18 mm.Samples were classified predominantly
as poorly graded,silty-sand (Smith-Emery Laboratories,2020).The specific sand placement locations
and volumes vary by year based on a variety of factors.The annual dredged sediment quantities from
1942 to 2021 for the Oceanside Harbor are shown in Table 2-4.
Jan. 4, 2022 Item 4 Page 118 of 229
Figure 2-9. Harbor Channels and Typical Discharge Locations
Table 2-3. 2012-2020 Sieve Analysis Data Summary (Smith-Emery Laboratories,
2020)
2012-2020 Harbor Dredging Year
USCS Gradation 2020 2018 2017 2014 2013 2012
Mean % Gravel 0.0 0.0 0.98 0.0 0.0 0.0
Mean % Sand 94.5 95.1 95.7 93.6 94.2 96.3
Mean % Fine 5.52 4.90 3.37 6.37 5.80 3.7
Mean D50 0.13 0.12 0.18 0.11 0.14 0.13
Legend
Navigation Channels
.'Approximate 2015-2020"‘’3“Discharge Locations
1230 1640
5mmLnienoflmlmHun-elm Madmanoi:m1mmcammn?sml=m
Figure 2-9.Harbor Channels and Ty@l Discharge Locations
Table 2-3.2012-2020 Sieve Analysis Data Summary (Smith-Emery Laboratories,
2020)
2012-2020 Harbor
Dredging
SCS Gradation 2020 2018 2017 2014 2013 2012
Mean %Gravel
Mean %Sand 94.5 95.1 95.7 93.6 94.2 96.3
Mean %Fine 5.52 4.90 3.37 6.37 5.80 3.7
Mean D50 0.13 0.12 0.18 0.11 0.14 0.13
Jan. 4, 2022 Item 4 Page 119 of 229
Table 2-4. Harbor Dredging Quantities for Oceanside Harbor (M&N 1982; USACE,
1991; Coastal Frontiers, 2018)
Year Dredge Quantity (cy) Year Dredge Quantity (cy)
1942-1944 1,500,000 1997 130,000
1945 219,000 1998 315,000
1957-1958 800,000 1999 187,000
1960 41,200 2000 327,000
1961 481,150 2001 80,000
1962-1963 3,810,700 2002 400,000
1965 111,400 2003 438,000
1966 684,000 2004 220,000
1967 177,900 2005 275,000
1968 433,900 2006 228,000
1969 353,000 2007 194,000
1971 551,900 2008 160,000
1973 434,100 2009 262,000
1974-1975 559,750 2010 270,000
1976 550,000 2011 180,000
1977-1978 318,550 2012 246,000
1981 463,000 2013 194,000
1984 475,000 2014 275,000
1986 450,000 2015 200,000
1988 220,000 2016 245,000
1990 249,818 2017 435,000
1992 188,345 2018 286,000
1994 483,000 2019 230,000
1995 161,000 2020 252,000
1996 162,000 2021 350,000
Average
Annual Bypass
Rate*
292,674 cy/yr
*Average annual bypass rate from 1945 to 2021, excludes beach nourishment and harbor improvements
2.3.2 Buena Vista Lagoon Restoration Project (AECOM, 2020)
The Buena Vista Lagoon, a State Ecological Reserve, provides habitat to a range of species and
recreation for the public. The project investigated freshwater, saltwater and hybrid approach-solutions
that will benefit the biological and hydrological functions of the lagoon. As dredging is involved in all
alternatives, this provides a potential opportunistic sand source for City beaches.
Our understanding is that the preferred alternative is the “Modified Saltwater Alternative”, which
combines aspects of the Saltwater and Hybrid A options. According to the 2019 Engineering analysis [9]Table 2-4.Harbor Dredging Quantities for Oceanside Harbor (M&N 1982;USAGE,
1991;Coastal Frontiers,2018)
Dredge Quantity (cy)Dredge Quantity (cy)
1942-1944 1,500,000 1997 130,000
1945 219,000 1998 315,000
1957-1958 800,000 1999 187,000
1960 41,200 2000 327,000
1961 481,150 2001 80,000
1962-1963 3,810,700 2002 400,000
1965 1 11,400 2003 438,000
1966 684,000 2004 220,000
1967 177,900 2005 275,000
1968 433,900 2006 228,000
1969 353,000 2007 194,000
1971 551,900 2008 160,000
1973 434,100 2009 262,000
1974-1975 559,750 2010 270,000
1976 550,000 2011 180,000
1977-1978 318,550 2012 246,000
1981 463,000 2013 194,000
1984 475,000 2014 275,000
1986 450,000 2015 200,000
1988 220,000 2016 245,000
1990 249,818 2017 435,000
1992 188,345 E 2018 286,000
1994 483,000 2019 230,000
1995 161,000 2020 252,000
1996 162,000 2021 350,000
Average
Annual Bypass 292,674 cylyr
Rate*
*Average annual bypass rate from 1945 to 2021,excludes beach nourishment and harbor improvements
2.3.2 Buena Vista Lagoon Restoration Project (AECOM,2020)
The Buena Vista Lagoon,a State Ecological Reserve,provides habitat to a range of species and
recreation for the public.The project investigated freshwater,saltwater and hybrid approach-solutions
that will benefit the biological and hydrological functions of the lagoon.As dredging is involved in all
alternatives,this provides a potential opportunistic sand source for City beaches.
Our understanding is that the preferred alternative is the “Modified Saltwater Alternative”,which
combines aspects of the Saltwater and Hybrid A options.According to the 2019 Engineering analysis
Jan. 4, 2022 Item 4 Page 120 of 229
memorandum, a total of 937,000 CY is proposed to be excavated or dredged as part of the
construction of this alternative. The disposal of this material is considered in two approaches:
• Approach 1: Dispose of suitable material on nearby beaches and nearshore, and fine-grained
material offshore.
• Approach 2: Dispose of suitable material on nearby beaches and the nearshore. Fine-grained
material would be disposed of in an on-site overdredge pit where existing material being
replaced is found to be suitable for beneficial reuse within the littoral zone, beach or
nearshore.
It is estimated that 798,000 CY of fine-grained material would be disposed of in the dredge pit under
Alternative 2. The disposal approaches being considered for the preferred alternative are shown in
Table 2-5.
Table 2-5. Disposal Plan for Buena Vista Lagoon Restoration Project
2.3.3 Corps San Luis Rey River Maintenance Dredging (City of Oceanside)
The USACE was tasked with dredging approximately 230,000 CY of sediment from the San Luis River
in 2016. This sand was to be redistributed for the nourishment along Oceanside’s beaches. Due to
issues regarding permits, endangered species habitat and the contractor’s time frame, the project was
delayed and initially rescheduled to the Fall of 2019. Today, this is considered an active, uncompleted
project.
2.4 Previous Sand Retention Concepts
2.4.1 Regional Beach Sand Retention Strategy (M&N, 2001)
The purpose of this report was to evaluate various sand retention strategies based on the needs and
opportunities of various beaches throughout San Diego. The City of Oceanside was assessed based
on the feasibility of an emergent groin field in the vicinity of Buccaneer Beach (Figure 2-10). The [Q]memorandum,a total of 937,000 CY is proposed to be excavated or dredged as part of the
construction of this alternative.The disposal of this material is considered in two approaches:
0 Approach 1:Dispose of suitable material on nearby beaches and nearshore,and fine-grained
material offshore.
0 Approach 2:Dispose of suitable material on nearby beaches and the nearshore.Fine-grained
material would be disposed of in an on-site overdredge pit where existing material being
replaced is found to be suitable for beneficial reuse within the littoral zone,beach or
nearshore.
It is estimated that 798,000 CY of fine-grained material would be disposed of in the dredge pit under
Alternative 2.The disposal approaches being considered for the preferred alternative are shown in
Table 2-5.
Table 2-5.Disposal Plan for Buena Vista Lagoon Etoration Project
I Volume of Disposal (c
Construction Approach Approach 1 Approach 2
Beach
Oceanside 1 19,000 245,000
North Carlsbad 0 0
Nearshore
Oceanside 33,000 692,000
LA-5 785,000 0
Total Export 937,000 931,000
2.3.3 Corps San Luis Rey River Mainterle Dredging (City of Oceanside)
The USACE was tasked with dredging approximately 230,000 CY of sediment from the San Luis River
in 2016.This sand was to be redistributed for the nourishment along Oceanside’s beaches.Due to
issues regarding permits,endangered species habitat and the contractor’s time frame,the project was
delayed and initially rescheduled to the Fall of 2019.Today,this is considered an active,uncompleted
project.
2.4 Previous Sand Retention Concepts
2.4.1 Regional Beach Sand Retention Strategy (M&N,2001)
The purpose of this report was to evaluate various sand retention strategies based on the needs and
opportunities of various beaches throughout San Diego.The City of Oceanside was assessed based
on the feasibility of an emergent groin field in the vicinity of Buccaneer Beach (Figure 2-10).The
Jan. 4, 2022 Item 4 Page 121 of 229
primary objectives of the structures were to minimize down drift impacts while retaining beach width.
Groin design considered cross shore length, pre-fill of sand in the groin fillets, and modification of the
federal sand bypassing program to extend south of the groin field. The conceptual design included
two groins spaced 1,500 feet apart with lengths of 930 feet. A maximum fillet width of 280 feet and
minimum beach width of 150 feet between groins was proposed with a total retained beach area of
750,000 square feet. The structure crest would be at an elevation of +14 feet MLLW at the beach
berm, which will then slope down to be submerged in the nearshore at an elevation of +3 feet MLLW.
Figure 2-10. Conceptual Groin Field Design at Buccaneer Beach (M&N, 2001)
2.4.2 Preliminary Engineering Report for Beach Protection Facilities (Noble Consultants,
1983)
Noble Consultants provided four alternative groin field designs (Figure 2-11) and recommended that
the groins be adjustable in height and length, be wave absorbent, and be constructed in conjunction
with beach nourishment. Additionally, the groins should extent offshore to -10 feet MSL (approximately
500-600 feet length) and be spaced 1,000 feet apart. [Q]primary objectives of the structures were to minimize down drift impacts while retaining beach width.
Groin design considered cross shore length,pre-fill of sand in the groin fillets,and modification of the
federal sand bypassing program to extend south of the groin field.The conceptual design included
two groins spaced 1,500 feet apart with lengths of 930 feet.A maximum fillet width of 280 feet and
minimum beach width of 150 feet between groins was proposed with a total retained beach area of
750,000 square feet.The structure crest would be at an elevation of +14 feet MLLW at the beach
berm,which will then slope down to be submerged in the nearshore at an elevation of +3 feet MLLW.
Equilibrium Shoreline(Net Transport South)
1000 0 1000
Salein Feet
+14feet -,_\‘\.\..\
Extended _
Sand Bypass =
.Discharge xE_IHaimntalScaleinFeet,\\//\l Location
ELEVATION®4
Figure 2-10.Conceptual Groin Field Design at Buccaneer Beach (M&N,2001)
2.4.2 Preliminary Engineering Report for Beach Protection Facilities (Noble Consultants,
1983)
Noble Consultants provided four alternative groin field designs (Figure 2—1 1)and recommended that
the groins be adjustable in height and length,be wave absorbent,and be constructed in conjunction
with beach nourishment.Additionally,the groins should extent offshore to -10 feet MSL (approximately
500-600 feet length)and be spaced 1,000 feet apart.
Jan. 4, 2022 Item 4 Page 122 of 229
• The first alternative design consists of 13 groins spaced 1,000 feet apart between the
Oceanside Pier and Buena Vista Lagoon. The cross-shore length would vary, stating 11
groins be 600 feet, one 400 feet, and one 200 feet.
• The second alternative would consist of 12 groins with varying spacing and length. Ten groins
would be 500 feet long, one 300 feet, and one 200 feet. Three groins would be spaced at
1,500 feet, one at 1,300 feet, six at 1,000 feet, one at 800 feet and one at 600 feet.
• The third alternative consists of 10 groins with varying spacing and length spread between
the Oceanside Pier and Cassidy Street. Eight groins would be 600 feet long, one 400 feet and
one 200 feet. Additionally, eight groins would be spaced 1,000 feet apart with one at 800 feet
and one at 600 feet.
• The fourth alternative consists of 8 groins with varying spacing and length spread between
the Oceanside Pier and the Loma Alta Creek. Six groins would be 650 feet long, one 400 feet
long and one 250 feet long. Six of the groins would be spaced at 650 feet apart and the
remaining two would be spaced 800 feet apart. [Q]The first alternative design consists of 13 groins spaced 1,000 feet apart between the
Oceanside Pier and Buena Vista Lagoon.The cross-shore length would vary,stating 11
groins be 600 feet,one 400 feet,and one 200 feet.
The second alternative would consist of 12 groins with varying spacing and length.Ten groins
would be 500 feet long,one 300 feet,and one 200 feet.Three groins would be spaced at
1,500 feet,one at 1,300 feet,six at 1,000 feet,one at 800 feet and one at 600 feet.
The third alternative consists of 10 groins with varying spacing and length spread between
the Oceanside Pier and Cassidy Street.Eight groins would be 600 feet long,one 400 feet and
one 200 feet.Additionally,eight groins would be spaced 1,000 feet apart with one at 800 feet
and one at 600 feet.
The fourth alternative consists of 8 groins with varying spacing and length spread between
the Oceanside Pier and the Loma Alta Creek.Six groins would be 650 feet long,one 400 feet
long and one 250 feet long.Six of the groins would be spaced at 650 feet apart and the
remaining two would be spaced 800 feet apart.
Jan. 4, 2022 Item 4 Page 123 of 229
Figure 2-11. Alternative groin field designs (Noble Consultants, 1983)
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Figure 2-11.Alternative groin field designs (Noble Consultants,1983)
Jan. 4, 2022 Item 4 Page 124 of 229
2.5 Review Similar Coastal Projects
Relevant project examples throughout the U.S. and internationally were reviewed for design
inspiration for Oceanside. Some of the most relevant projects reviewed are summarized in this section.
2.5.1 Groin Concepts
2.5.1.1 Upham Beach Shoreline Stabilization Project, Pinellas County, Florida
The goal of this project was to stabilize Upham Beach, which is situated downdrift of the Blind Pass
Inlet, with sand retention devices. Given regulatory challenges surrounding potential downdrift and
surfing impacts, the County of Pinellas teamed with a local university to study an easily deployable
and reversible system. The project installed five temporary geotextile T-head groins in 2005, which
are shown in Figure 2-12. The five groins were constructed from 44 geotextile tubes, with three
geotubes in the base layer, two in the center and one on top (Elko & Mann, 2006). After a period of
about five years, the groins were determined successful in retaining an adequate beach width while
minimizing down drift impacts. Given the success, the temporary geotextile groins were replaced with
permanent rock groins within minor alterations in configuration in 2018.
Figure 2-12. Design layout of Upham Beach groins (Elko & Mann, 2006)
2.5.1.2 Lower Newport Beach Groin Field, Newport Beach, California
This region of Newport Beach (Figure 2-13) contains eight rubble mound groins constructed by the
U.S. Army Corps of Engineers between 1969 and 1973 to slow erosion and increase beach widths
along approximately 6,000 linear feet of the City of Newport’s shoreline. The groins are spaced 750 [6]2.5 Review Similar Coastal Projects
Relevant project examples throughout the U.S.and internationally were reviewed for design
inspiration for Oceanside.Some of the most relevant projects reviewed are summarized in this section.
2.5.1 Groin Concepts
2.5.1.1 Upham Beach Shoreline Stabilization Project,Pinellas County,Florida
The goal of this project was to stabilize Upham Beach,which is situated downdrift of the Blind Pass
Inlet,with sand retention devices.Given regulatory challenges surrounding potential downdrift and
surfing impacts,the County of Pinellas teamed with a local university to study an easily deployable
and reversible system.The project installed five temporary geotextile T-head groins in 2005,which
are shown in Figure 2—12.The five groins were constructed from 44 geotextile tubes,with three
geotubes in the base layer,two in the center and one on top (Elko &Mann,2006).After a period of
about five years,the groins were determined successful in retaining an adequate beach width while
minimizing down drift impacts.Given the success,the temporary geotextile groins were replaced with
permanent rock groins within minor alterations in configuration in 2018.
sun-mm-HEAD ’3 0:01am:T-l'EAD
or I._,M9000 'Figure 4.Design of the Upham .x.,Beach project Including nourlshrnent,'\°15°.-
five geotextlle T-grolns,and closure .GRAPHIC:SCALE.m‘of the south jetty/breakwater gap.h 7 ,7 7 ~#494 r 1''
Figure 2-12.Design layout of Upham Beach groins (Elko &Mann,2006)
2.5.1.2 Lower Newport Beach Groin Field,Newport Beach,California
This region of Newport Beach (Figure 2—13)contains eight rubble mound groins constructed by the
U.S.Army Corps of Engineers between 1969 and 1973 to slow erosion and increase beach widths
along approximately 6,000 linear feet of the City of Newport’s shoreline.The groins are spaced 750
Jan. 4, 2022 Item 4 Page 125 of 229
feet to 900 feet apart and vary in length from 400 to 650 feet. Relative to pre-construction, surveys by
the Corps collected from 1978 to 1995 have shown a higher volume of sand retained and a widening
of the beaches (USACE, 1998).
Figure 2-13. West Newport Beach Groins - South (DBW & SCC, 2002)
2.5.1.3 Chevron Groin, El Segundo Beach, California
In response to high rates of erosion along the shoreline fronting the Chevron facility in 1982-1983,
Chevron proposed a 900 ft long, 65 to 100 ft wide groin with beach fill to protect exposed pipes and
its facility. This struck a large debate between Chevron and Surfrider, in that the groin would have
adverse effects on the surf conditions at El Segundo Beach and specifically at the updrift groin.
Chevron was granted approval for the groin by the CCC so long as surfing monitoring efforts were
carried out for a period of five years. Should surfing impacts be realized during this period, Chevron
would be responsible to mitigate for those impacts. Following the construction of the Chevron groin
and monitoring period, it was concluded that the surf at the updrift groin had been negatively impacted.
It was determined that mitigation for these impacts would take the form of a surfing reef, ultimately
called Pratt’s Reef, and was constructed in 2000. The reef was constructed of geotextile bags that
degraded in the marine environment quickly. The reef was also small and placed in shallow water; the
scale was a function of the limited Project funding (about $1M). The reef was ultimately deemed
unsuccessful in creating surf-able waves and was removed in 2008. [Q]feet to 900 feet apart and vary in length from 400 ta?feet.Relative to pre-construction,surveys by
igher volume of sand retained and a wideningtheCorpscollectedfrom1978 to 1995 have show
of the beaches (USACE,1998).
Figure 2-13.West Newport Beach Groins -South (DBW &$66,2002)
2.5.1.3 Chevron Groin,El Segundo Beach,California
In response to high rates of erosion along the shoreline fronting the Chevron facility in 1982-1983,
Chevron proposed a 900 ft long,65 to 100 ft wide groin with beach fill to protect exposed pipes and
its facility.This struck a large debate between Chevron and Surfrider,in that the groin would have
adverse effects on the surf conditions at El Segundo Beach and specifically at the updrift groin.
Chevron was granted approval for the groin by the CCC so long as surfing monitoring efforts were
carried out for a period of five years.Should surfing impacts be realized during this period,Chevron
would be responsible to mitigate for those impacts.Following the construction of the Chevron groin
and monitoring period,it was concluded that the surfat the updrift groin had been negatively impacted.
It was determined that mitigation for these impacts would take the form of a surfing reef,ultimately
called Pratt’s Reef,and was constructed in 2000.The reef was constructed of geotextile bags that
degraded in the marine environment quickly.The reef was also small and placed in shallow water;the
scale was a function of the limited Project funding (about $1 M).The reef was ultimately deemed
unsuccessful in creating surf-able waves and was removed in 2008.
Jan. 4, 2022 Item 4 Page 126 of 229
2.5.1.4 Imperial Beach Groins, Imperial Beach, California (Curren, C. & Chatham, C., 1997)
In response to high rates of erosion in the 1950’s, the U.S. Army Corps of Engineers constructed two
groins between 1959 and 1963. The groins are 400-feet and 740-feet long, spaced approximately
1,325 ft apart (Figure 2-14). The first groin was 400-feet long and was constructed in 1959. It was
deemed unsuccessful at retaining adequate beach widths, which led to the construction of the second
groin in the early 1960’s. The second groin was 300-feet longer than the first and was still deemed
ineffective at retaining beach width at that time. From a review of aerial images, these groins appeared
effective at retaining the coarse gradation sand from the RBSP II Project in 2012. These structures
were a part of an original five groin plan, which was further evaluated in a 1977 hydraulic modeling
study.
Figure 2-14. Imperial Beach Groins (Google Earth, 2021)
2.5.1.5 Agua Hedionda Jetties, Carlsbad, California
The Agua Hedionda jetties were constructed in 1954 to stabilize the lagoon inlet and allow for
continuous flow of cool water for the power plant (M&N, 2001). Two twin jetties systems were
constructed, one to the north at Tamarack Beach and one to the south fronting the powerplant (Figure
2-15). These structures have an approximate fillet angle of 2.5 degrees and a blocking distance of
150-ft for the northside and 250-ft for the southside (M&N, 2001). The inlet channel between the
northern system is approximate 200-ft wide and approximately 70-ft wide for the southern system.
These structures were evaluated in regard to sediment retention and blocking. [Q]2.5.1.4 Imperial Beach Groins,Imperial Beach,California (Curren,C.&Chatham,C.,1997)
In response to high rates of erosion in the 1950's,the U.S.Army Corps of Engineers constructed two
groins between 1959 and 1963.The groins are 400—feet and 740-feet long,spaced approximately
1,325 ft apart (Figure 2-14).The first groin was 400—feet long and was constructed in 1959.It was
deemed unsuccessful at retaining adequate beach widths,which led to the construction of the second
groin in the early 1960's.The second groin was 300—feet longer than the first and was still deemed
ineffective at retaining beach width at that time.From a review of aerial images,these groins appeared
effective at retaining the coarse gradation sand from the RBSP II Project in 2012.These structures
were a part of an original five groin plan,which was further evaluated in a 1977 hydraulic modeling
study.
is .it -~2 32?....
Figure 2-14.Imperial Beach Groins (Google Earth,2021)
2.5.1.5 Agua Hedionda Jetties,Carlsbad,California
The Agua Hedionda jetties were constructed in 1954 to stabilize the lagoon inlet and allow for
continuous flow of cool water for the power plant (M&N,2001).Two twin jetties systems were
constructed,one to the north at Tamarack Beach and one to the south fronting the powerplant (Figure
2—15).These structures have an approximate fillet angle of 2.5 degrees and a blocking distance of
150-ft for the northside and 250-ft for the southside (M&N,2001).The inlet channel between the
northern system is approximate 200-ft wide and approximately 70—ft wide for the southern system.
These structures were evaluated in regard to sediment retention and blocking.
Jan. 4, 2022 Item 4 Page 127 of 229
Figure 2-15. Agua Hedionda Jetties (Google Earth, 2021)
2.5.2 Artificial Reefs
2.5.2.1 Palm Beach Artificial Reef, Gold Coast, Australia
The Palm Beach Artificial Reef was constructed from 2017 to 2019 in accordance with the City of Gold
Coast Ocean Beach Strategy. It cost $12.5M and is approximately 160 meters (~525 feet) long, 80
meters (262.5 feet) wide and is located 270 meters (~886 feet) offshore (Figure 2-16) (City of Gold
Coast, 2019). It consists of 80,000 CY of 5 to 8-ton armor rock and was supplied with 615,000 CY of
pre-fill beach nourishment. It was designed to protect the shoreline south of the reef by dissipating
incoming waves and surrounding currents, while also providing a surfing resource. [6]___,h ..'..“'-o -,'sg
Figure 2-15.Agua Hedionda Jetties (Google Earth,2021)
2.5.2 Artificial Reefs
2.5.2.1 Palm Beach Artificial Reef,Gold Coast,Australia
The Palm Beach Artificial Reef was constructed from 2017 to 2019 in accordance with the City of Gold
Coast Ocean Beach Strategy.It cost $12.5M and is approximately 160 meters (~525 feet)long,80
meters (262.5 feet)wide and is located 270 meters (~886 feet)offshore (Figure 2-16)(City of Gold
Coast,2019).It consists of 80,000 CY of 5 to 8-ton armor rock and was supplied with 615,000 CY of
pre-fill beach nourishment.It was designed to protect the shoreline south of the reef by dissipating
incoming waves and surrounding currents,while also providing a surfing resource.
Jan. 4, 2022 Item 4 Page 128 of 229
Figure 2-16. Palm Beach Artificial Surf Reef (Source: City of Gold Coast, 2019)
2.5.3 Sand Bypassing
2.5.3.1 Tweed River Sand Bypassing, Gold Coast, Australia
Of the 35 regular sand bypass and transfer systems operating in Australia, the bypass operating at
the mouth of the Tweed River is one of the largest, transferring around 500,000m3 each year at an
average annual cost of $7.6M AUD. Of the many bypass operations, the Tweed Sand Bypass (TSB)
has been selected as a relevant example given its proximity to world class surf breaks and its role in
modifying surf conditions. The TSB also demonstrates how bypass systems can work with natural
processes to accommodate multiple, and sometimes competing, priorities for coasts and beaches.
The TSB was constructed in 2001 to establish and maintain a navigable entrance to the Tweed River
and to restore and maintain coastal sand supply along the southern Gold Coast beaches (refer to
Figure 2-17). The project was designed and constructed under a 24-year ‘build, own, operate and
transfer’ contract with the state government partners, a form of Public-Private Partnership (PPP).
/5 ‘5 am.-_,‘_...
Figure 2-16.Palm Beach Artificial Surf Reef (Source:City of Gold Coast,2019)
2.5.3 Sand Bypassing
2.5.3.1 Tweed River Sand Bypassing,Gold Coast,Australia
Of the 35 regular sand bypass and transfer systems operating in Australia,the bypass operating at
the mouth of the Tweed River is one of the largest,transferring around 500,000m3 each year at an
average annual cost of $7.6M AUD.Of the many bypass operations,the Tweed Sand Bypass (TSB)
has been selected as a relevant example given its proximity to world class surf breaks and its role in
modifying surf conditions.The TSB also demonstrates how bypass systems can work with natural
processes to accommodate multiple,and sometimes competing,priorities for coasts and beaches.
The TSB was constructed in 2001 to establish and maintain a navigable entrance to the Tweed River
and to restore and maintain coastal sand supply along the southern Gold Coast beaches (refer to
Figure 2—17).The project was designed and constructed under a 24-year ‘build,own,operate and
transfer’contract with the state government partners,a form of Public-Private Partnership (PPP).
Jan. 4, 2022 Item 4 Page 129 of 229
Figure 2-17. Tweed Sand Bypass Overview (TSB, 2020)
Under the agreement, the Tweed River Entrance Sand Bypassing Company operates a sand
bypassing jetty facility comprised of a 450 m (~1,500 ft) long permanent fixed jetty structure that is
sited around 250 m (~820 ft) south of the Tweed River entrance and extends offshore to the -5.0m(~16
ft) Indian Spring Low Water (ISLW) contour. The jetty supports ten jet pumps installed in series that
are buried beneath the seabed (refer to Figure 2-18). When operational, the jet pumps create cones
in the sand that intersect each other to form a trench at right angles to the beach alignment which
captures the sand moved by waves and currents along the more active portion of the beach profile. [6]TWEEDSANDBYPASSING
Viv.Pll
Mm SandTmflll allm
-Iempwary SuflTmlier Pbei'ne
Figure 2-17.Tw ed Sand Bypass Overview (T53,2020)
Under the agreement,the Tweed River Entrance Sand Bypassing Company operates a sand
bypassing jetty facility comprised of a 450 m (~1,500 ft)long permanent fixed jetty structure that is
sited around 250 m (~820 ft)south ofthe Tweed River entrance and extends offshore to the -5.0m(~16
ft)Indian Spring Low Water (ISLW)contour.The jetty supports ten jet pumps installed in series that
are buried beneath the seabed (refer to Figure 2-18).When operational,the jet pumps create cones
in the sand that intersect each other to form a trench at right angles to the beach alignment which
captures the sand moved by waves and currents along the more active portion of the beach profile.
Jan. 4, 2022 Item 4 Page 130 of 229
Figure 2-18. Tweed Sand Bypass Intake System (GHD, 2011)
The sand is pumped hydraulically to a sump located at the onshore end of the structure from where it
is again pumped via a slurry pump into a 400 mm (~16-inche) diameter discharge pipeline. The
discharge pipeline crosses under the Tweed River and directs sand slurry to outlets located at
Duranbah beach, Snapper Rocks (East and West) and Kirra Point, as shown in Figure 2-17. Once
discharged the sand is reworked northwards by natural coastal processes across and along the beach
profile.
Amongst the global surf community, the project is famous for the development of a long continuous
surfing bank from Snapper Rocks to Coolangatta known as the ‘Superbank’.
It is important to note that due to the large number of different beach users, the project hasn’t been
considered a success by all. Given the varied preferences of beach users, debates have arisen about
which stakeholder’s interests should be prioritized.
Sand and water mixtuntomainpumpstation
Wave action pushes Jet pump at the bottom ofandintothecondo-op the cone collects theeonotrappedand
Figure 2-18.Tweed Sand Bypass Intake System (GHD,2011)
The sand is pumped hydraulically to a sump located at the onshore end of the structure from where it
is again pumped via a slurry pump into a 400 mm (~16-inche)diameter discharge pipeline.The
discharge pipeline crosses under the Tweed River and directs sand slurry to outlets located at
Duranbah beach,Snapper Rocks (East and West)and Kirra Point,as shown in Figure 2-17.Once
discharged the sand is reworked northwards by natural coastal processes across and along the beach
profile.
Amongst the global surf community,the project is famous for the development of a long continuous
surfing bank from Snapper Rocks to Coolangatta known as the ‘Superbank’.
It is important to note that due to the large number of different beach users,the project hasn’t been
considered a success by all.Given the varied preferences of beach users,debates have arisen about
which stakeholder’s interests should be prioritized.
Jan. 4, 2022 Item 4 Page 131 of 229
Excess sand quantities were of particular concern at Kirra, where the offshore reef was significantly
impacted by increased sand levels, raising ecological issues and limiting the recreation potential of
the reef for SCUBA diving and fishing (Castelle et al., 2006, Lazarow, 2007). In addition, the once
world class surf break to the west of Kirra Point groin suffered as the previously well aligned sandbanks
were buried by excess sand and as a result became poorly aligned to the predominant swells
(Lazarow, 2007).
Another key lesson learned from the TSB project has been the involvement of key stakeholders since
the project’s inception. The Community Advisory Committee has included representatives of local
universities, commercial and recreational fishers, divers, boardriders clubs, surf lifesaving clubs and
marine rescue organizations. This has enabled the design, construction and operation of the TSB to
be tailored as far as practicable to suit the varied preferences of beach users. Regular communication
has also ensured that debates are well informed using the best available data.
2.5.3.2 Mobile Sand Backpassing System, Noosa, Australia
Noosa Main Beach is a prime holiday destination, situated on the Sunshine Coast, approx. 90-minute
drive north from Brisbane. Noosa Main Beach has a history of erosion during cyclones and storm
events, which has a detrimental effect on the amenity of the beach.
Noosa Main Beach is directly adjacent to the Noosa river mouth which is highly mobile by nature.
Southerly movement of the river entrance at the northern end of the main beach is constrained by a
rock groin and another groin is located approximately half way along the beach, between the surf club
and the river entrance. The littoral drift along the main beach is from south to north, with sand able to
be captured against the most northern groin (Figure 2-19).
Figure 2-19. Sandshifters on Noosa Beach, Queensland
In 2005, a sand recycling system was piloted to capture sand at the northern end of the beach and
recycle or backpass sand 1.5km south to the Surf Club. The system implemented was a diesel
powered Sandshifter, which remained in place for approximately three years and was capable of
recycling 30,000m3/yr.
Following the success of this trial, approval was given for a permanent electrically powered installation,
the installation and commissioning of which was completed in January 2012. The system is semi-
automated and is capable of being operated from Slurry Systems office in Gippsland, Victoria. The
new system is capable of recycling 60,000m3/yr and had a capital cost of approximately $1.5M. [Q]Excess sand quantities were of particular concern at Kirra,where the offshore reef was significantly
impacted by increased sand levels,raising ecological issues and limiting the recreation potential of
the reef for SCUBA diving and fishing (Castelle et al.,2006,Lazarow,2007).In addition,the once
world class surf break to the west of Kirra Point groin suffered as the previously well aligned sandbanks
were buried by excess sand and as a result became poorly aligned to the predominant swells
(Lazarow,2007).
Another key lesson learned from the TSB project has been the involvement of key stakeholders since
the project’s inception.The Community Advisory Committee has included representatives of local
universities,commercial and recreational fishers,divers,boardriders clubs,surf lifesaving clubs and
marine rescue organizations.This has enabled the design,construction and operation of the TSB to
be tailored as far as practicable to suit the varied preferences of beach users.Regular communication
has also ensured that debates are well informed using the best available data.
2.5.3.2 Mobile Sand Backpassing System,Noosa,Australia
Noosa Main Beach is a prime holiday destination,situated on the Sunshine Coast,approx.90-minute
drive north from Brisbane.Noosa Main Beach has a history of erosion during cyclones and storm
events,which has a detrimental effect on the amenity of the beach.
Noosa Main Beach is directly adjacent to the Noosa river mouth which is highly mobile by nature.
Southerly movement of the river entrance at the northern end of the main beach is constrained by a
rock groin and another groin is located approximately half way along the beach,between the surf club
and the river entrance.The littoral drift along the main beach is from south to north,with sand able to
be captured against the most northern groin (Figure 2-19).
Figure 2-19.Sandshifters on Noosa Beach,Queensland
In 2005,a sand recycling system was piloted to capture sand at the northern end of the beach and
recycle or backpass sand 1.5km south to the Surf Club.The system implemented was a diesel
powered Sandshifter,which remained in place for approximately three years and was capable of
recycling 30,000m3/yr.
Following the success of this trial,approval was given for a permanent electrically powered installation,
the installation and commissioning of which was completed in January 2012.The system is semi-
automated and is capable of being operated from Slurry Systems office in Gippsland,Victoria.The
new system is capable of recycling 60,000m3/yr and had a capital cost of approximately $1.5M.
Jan. 4, 2022 Item 4 Page 132 of 229
The Sunshine Coast Regional Council have a 10-year lease on the equipment and pay Slurry Systems
$11,000/month for the lease and to maintain the equipment. In addition, Slurry Systems receive
payment per cubic meter of sand pumped through the system ($3.50/m3). A densitometer has been
installed to measure the amount of sand which passes through the pipeline as a means of calculating
payment.
Discussions with Sunshine Coast Regional Council noted that the densitometer caused significant
delays in the commissioning of the system due to Customs and approvals processes related to its
nuclear components and overseas manufacture (Germany). This is an item with a long lead time and
permitting requirements which need to be considered if entering into a construction contract.
As the beach is a highly utilized public facility, the system only operates at night and during off peak
periods. From a public safety perspective, care needs to be taken at the outfall to ensure it is clear of
people and obstructions prior to pumping commencing.
Outfall flexibility has been allowed for with multiple outlets provided in the pipeline which runs under a
boardwalk at the back of the beach.
A pump house has been constructed behind the back dune which houses the pumps and electrical
automation equipment. A slurry trap is also included, which screens any debris before the sediment
moves through to the slurry transfer pumps. These features are shown in Figure 2-20.
[Q]The Sunshine Coast Regional Council have a 10-year lease on the equipment and pay Slurry Systems
$11,000/month for the lease and to maintain the equipment.In addition,Slurry Systems receive
payment per cubic meter of sand pumped through the system ($3.50/m3).A densitometer has been
installed to measure the amount of sand which passes through the pipeline as a means of calculating
payment.
Discussions with Sunshine Coast Regional Council noted that the densitometer caused significant
delays in the commissioning of the system due to Customs and approvals processes related to its
nuclear components and overseas manufacture (Germany).This is an item with a long lead time and
permitting requirements which need to be considered if entering into a construction contract.
As the beach is a highly utilized public facility,the system only operates at night and during off peak
periods.From a public safety perspective,care needs to be taken at the outfall to ensure it is clear of
people and obstructions prior to pumping commencing.
Outfall flexibility has been allowed for with multiple outlets provided in the pipeline which runs under a
boardwalk at the back of the beach.
A pump house has been constructed behind the back dune which houses the pumps and electrical
automation equipment.A slurry trap is also included,which screens any debris before the sediment
moves through to the slurry transfer pumps.These features are shown in Figure 2-20.
ill
L‘.'
\lfi
Jan. 4, 2022 Item 4 Page 133 of 229
Figure 2-20. Clockwise from top left: Pump Station; Slurry Sump; Electric Motors
2.5.3.3 Indian River Inlet, Delaware
The Indian River Inlet, located in Bethany Beach, Delaware, operates annual sand bypassing from
the south side of the inlet to the north side. The inlet is stabilized by a system of two parallel jetties
which were constructed in 1938-1939 (Gerbert et al., 1992). Since the construction of these jetties,
the beach on the north side of the inlet began to retreat. The littoral drift pattern for this portion of the
coastline reflects 110,000 CY of sediment moving to the north annually (Gerbert et al., 1992).
A sand bypassing system was designed to bypass the annual quantity of 110,000 CY and began
operation in 1990 (Gerbert et al., 1992). The system consists of a crawler crane mounted jet pump
operating on the south side beach, a pump house adjacent to the south jetty, and piping across the
highway bridge to transport sediment (Figure 2-21) (Boswood & Murray, 2001). The jet pump system
creates an 18-ft deep, 48-ft diameter crater in the intertidal zone and is designed to pump at a rate of
200 CY/hr (Boswood & Murray, 2001). This final cost for this bypass system was $1.7 million and
annual operating and maintenance costs are estimated to be $290,000 (Boswood & Murray, 2001). [Q]Figure 2-20.Clockwise from top left:Pump Station;Slurry Sump;Electric Motors
2.5.3.3 Indian River Inlet,Delaware
The Indian River Inlet,located in Bethany Beach,Delaware,operates annual sand bypassing from
the south side of the inlet to the north side.The inlet is stabilized by a system of two parallel jetties
which were constructed in 1938-1939 (Gerbert et al.,1992).Since the construction of these jetties,
the beach on the north side of the inlet began to retreat.The littoral drift pattern for this portion of the
coastline reflects 110,000 CY of sediment moving to the north annually (Gerbert et al.,1992).
A sand bypassing system was designed to bypass the annual quantity of 110,000 CY and began
operation in 1990 (Gerbert et al.,1992).The system consists of a crawler crane mounted jet pump
operating on the south side beach,a pump house adjacent to the south jetty,and piping across the
highway bridge to transport sediment (Figure 2-21)(Boswood &Murray,2001).The jet pump system
creates an 18-ft deep,48-ft diameter crater in the intertidal zone and is designed to pump at a rate of
200 CY/hr (Boswood &Murray,2001).This final cost for this bypass system was $1.7 million and
annual operating and maintenance costs are estimated to be $290,000 (Boswood &Murray,2001 ).
Jan. 4, 2022 Item 4 Page 134 of 229
Figure 2-21. Indian River Inlet Sand Bypass System (USACE, 2020)
[Q]Figure 2-21.Indian River Inlet Sand Bypass System (USAGE,2020)
Jan. 4, 2022 Item 4 Page 135 of 229
3. References
1. Boswood, P.K. & Murray R.J. 2001. World-wide Sand Bypassing Systems: Data report.
Conservation Technical Report No. 15. Queensland Government. Retrieved from:
https://tamug-
ir.tdl.org/bitstream/handle/1969.3/28472/US%20ACE%20Report.on.Bypass.Systems..pdf?seq
uence=1
2. California Department of Boating and Waterways and State Coastal Conservancy, 2002.
California Beach Restoration Study. Sacramento, California.
3. Curren, C. & Chatham C. 1977. Imperial Beach, California. Design of Structures for Beach
Erosion Control. Hydrualic Model Investigation. Technical report H-77-15.
4. Coastal Frontiers Corporation. 2019. Regional Beach Monitoring Program Annual Report.
Retrieved from: https://www.sandag.org/index.asp?projectid=298&fuseaction=projects.detail
5. Elko, N.A., & Mann D.W. 2006. Implementation of Geotextile T-groins in Pinellas County
Florida. Shore and Beach. Volume 75, No. 2. Retrieved from:
https://pdfs.semanticscholar.org/a1fe/ccbbd073749af8abb2afe832c1bffe984783.pdf
6. Environmental Science Associates (ESA). 2018. Coastal Hazard Vulnerability Assessment,
City of Oceanside. Retrieved from:
https://www.ci.oceanside.ca.us/civicax/filebank/blobdload.aspx?blobid=48346
7. Gerbert, J.A., Watson, K., & Rambo, A. 1992. 57 Years of Coastal Engineering Practice at a
Problem Inlet: Indian River Inlet, Delaware.
8. Moffatt & Nichol Engineers. (1982). Experimental Sand Bypass System at Oceanside Harbor,
California.
9. Moffatt & Nichol Engineers. (1990). Sediment Budget Report Oceanside Littoral Cell. Coast of
California Storm and Tidal Waves Study, CCSTWS 90-2.
10. Moffatt & Nichol Engineers. (2001). Regional Beach Sand retention Strategy. Retrieved from:
https://www.sandag.org/uploads/publicationid/publicationid_2036_20694.pdf
11. Moffatt & Nichol Engineers. (2016) San Diego County Shoreline Protection Feasibility Study,
Final Sampling Analysis Plan Results Report.
12. NOAA CO-OPS, 2020. https://tidesandcurrents.noaa.gov/met.html?id=9410230 . Date
accessed: 07/30/2020.
13. Noble Consultants, Inc. 1983. Preliminary Engineering Report. Beach Protection Facilities:
Oceanside, California.
14. Noble Consultants, Inc. 2001. Final Construction Management Documents, San Diego
Regional Beach Sand Project. Irvine, CA.
15. Patsch K. & Griggs, G. 2007. Development of Sand Budgets for California’s Major Littoral
Cells. Retrieved from:
https://dbw.parks.ca.gov/pages/28702/files/Sand_Budgets_Major_Littoral_Cells.pdf "’[3]References
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ir.td|.org/bitstream/handle/1969.3/28472/US%20ACE%20Report.on.Bypass.Systems..pdf?seq
uence=1
California Department of Boating and WatenNays and State Coastal Conservancy,2002.
California Beach Restoration Study.Sacramento,California.
Curren,C.&Chatham C.1977.Imperial Beach,California.Design of Structures for Beach
Erosion Control.Hydrualic Model Investigation.Technical report H-77-15.
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Retrieved from:https://www.sandag.org/index.asp?projectid=298&fuseaction=projects.detail
Elko, N.A.,&Mann D.W.2006.Implementation of Geotextile T-groins in Pinellas County
Florida.Shore and Beach.Volume 75,No.2.Retrieved from:
https://pdfs.semanticscholar.org/a1fe/ccbbd073749af8abb2afe832c1 bffe984783.pdf
Environmental Science Associates (ESA).2018.Coastal Hazard Vulnerability Assessment,
City of Oceanside.Retrieved from:
https://www.ci.oceanside.ca.us/civicax/filebank/blobdload.aspx?blobid=48346
Gerbert,J.A.,Watson,K.,&Rambo,A.1992.57 Years of Coastal Engineering Practice at a
Problem Inlet:Indian River Inlet,Delaware.
Moffatt &Nichol Engineers.(1982).Experimental Sand Bypass System at Oceanside Harbor,
California.
Moffatt &Nichol Engineers.(1990).Sediment Budget Report Oceanside Littoral Cell.Coast of
California Storm and Tidal Waves Study,CCSTWS 90-2.
Moffatt &Nichol Engineers.(2001).Regional Beach Sand retention Strategy.Retrieved from:
https://www.sandag.org/uploads/publicationid/publicationid_2036_20694.pdf
Moffatt &Nichol Engineers.(2016)San Diego County Shoreline Protection Feasibility Study,
Final Sampling Analysis Plan Results Report.
NOAA CO-OPS,2020.https://tidesandcurrents.noaa.gov/met.html?id=9410230 .Date
accessed:07/30/2020.
Noble Consultants,Inc.1983.Preliminary Engineering Report.Beach Protection Facilities:
Oceanside,California.
Noble Consultants,Inc.2001.Final Construction Management Documents,San Diego
Regional Beach Sand Project.Irvine,CA.
Patsch K.&Griggs,G.2007.Development of Sand Budgets for California’s Major Littoral
Cells.Retrieved from:
https://dbw.parks.ca.gov/pages/28702/fiIes/Sand_Budgets_Major_Littoral_CelIs.pdf
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16. SANDAG, 2019. Regional Shoreline Monitoring Program.
https://www.sandag.org/index.asp?projectid=298&fuseaction=projects.detail. Date accessed:
06/01/2021.
17. Sea Surveyor Inc.1999. San Diego Regional Beach Sand Project Final Report, Offshore
Sand Investigations.
18. Smith-Emery Laboratories. 2020. Oceanside Harbor Maintenance Dredging, Sieve Analysis
Data Summary.
19. TekMarine, Inc. 1987. Oceanside Littoral Cell Preliminary Sediment Budget Report. Coast of
California Storm and Tidal Waves Study, CCSTWS 87-4.
20. United States Army Corps of Engineers (USACE). 1991. California Coastal Storm and Tidal
Waves Study for San Diego.
21. United States Army Corps of Engineers (USACE). 1994. Oceanside Shoreline
Reconnaissance Report.
22. United States Army Corps of Engineers (USACE). 1995. Sand Bypass System-Phase III
Oceanside Harbor. Construction Solicitation and Specifications. RFP No. DACW09-95-R-
0013.
23. United States Army Corps of Engineers (USACE). 1996. Oceanside Sand Bypass Removal.
Construction Solicitation and Specifications. IFB No. DACW09-96-B-0024.
24. United States Army Corps of Engineers (USACE). 1998. San Gabriel to Newport Bay Erosion
Control Project, Orange County, California, 30 Years of Periodic beach Replenishment.
25. United States Army Corps of Engineers (USACE). 2016. San Diego County Shoreline
Feasibility Study, City of Oceanside, Report Synopsis.
26. United States Army Corps of Engineers (USACE). 2020. Wave Information Studies.
http://wis.usace.army.mil. Date accessed: 07/28/20.
27. United States Army Corps of Engineers (USACE). 2020. Delaware Coast Protection, Sand
Bypass Plant, Indian River Inlet. https://www.nap.usace.army.mil/Missions/Factsheets/Fact-
Sheet-Article-View/Article/490790/delaware-coast-protection-sand-bypass-plant-indian-river-
inlet/ [Q]16.
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SANDAG,2019.Regional Shoreline Monitoring Program.
https://www.sandag.org/index.asp?projectid=298&fuseaction=projects.detail.Date accessed:
06/01/2021.
Sea Surveyor Inc.1999.San Diego Regional Beach Sand Project Final Report,Offshore
Sand Investigations.
Smith-Emery Laboratories.2020.Oceanside Harbor Maintenance Dredging,Sieve Analysis
Data Summary.
TekMarine,Inc.1987.Oceanside Littoral Cell Preliminary Sediment Budget Report.Coast of
California Storm and Tidal Waves Study,CCSTWS 87-4.
United States Army Corps of Engineers (USACE).1991.California Coastal Storm and Tidal
Waves Study for San Diego.
United States Army Corps of Engineers (USACE).1994.Oceanside Shoreline
Reconnaissance Report.
United States Army Corps of Engineers (USACE).1995.Sand Bypass System-Phase III
Oceanside Harbor.Construction Solicitation and Specifications.RFP No.DACW09-95-R—
0013.
United States Army Corps of Engineers (USACE).1996.Oceanside Sand Bypass Removal.
Construction Solicitation and Specifications.IFB No.DACW09—96-B-0024.
United States Army Corps of Engineers (USACE).1998.San Gabriel to Newport Bay Erosion
Control Project,Orange County,California,30 Years of Periodic beach Replenishment.
United States Army Corps of Engineers (USACE).2016.San Diego County Shoreline
Feasibility Study,City of Oceanside,Report Synopsis.
United States Army Corps of Engineers (USACE).2020.Wave Information Studies.
http://wis.usace.army.mil.Date accessed:07/28/20.
United States Army Corps of Engineers (USACE).2020.Delaware Coast Protection,Sand
Bypass Plant,Indian River Inlet.https://www.nap.usace.army.mil/Missions/Factsheets/Fact—
Sheet—Article-View/Article/490790/delaware-coast-protection-sand-bypass-plant—indian-river—
inlet/
Jan. 4, 2022 Item 4 Page 137 of 229
APPENDIX B
Technical Report: Numerical Modeling of Alternatives
APPENDIX B
Technical Report:Numerical Modeling of Alternatives
Jan. 4, 2022 Item 4 Page 138 of 229
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APPENDIX B
Numerical Modeling Technical Report
This appendix presents the technical inputs and findings from the numerical modeling of Project alternatives.
1. Model Selection
The numerical model chosen to evaluate the effectiveness of each concept option was the Littoral Processes
and Coastline Kinetics (LITPACK), part of the MIKE suite of modeling applications developed by Delft Hydraulic
Institute (DHI). LITPACK is designed to model long term shoreline evolution for the purpose of optimizing and
evaluating the design and development of coastal works. This model is regularly updated, and the most recent
version (2020) is used for the project. The model is known as a 1-contour line model and requires that the
beach profile shape remains relatively constant as is moves seaward or shoreward seasonally so that change
in beach volume is directly related to shoreline change (USACE, 2014). The model couples hydrodynamic and
sediment transport models to calculate littoral drift rates and the coastline position across the model domain
over the simulation period.
To assess long term effects of sediment movement effectively for this project, a model that could resolve
transport and hydrodynamic conditions around offshore and nearshore structures such as groins and detached
breakwaters was needed. LITPACK allows for offshore breakwaters, groins, and revetments to be included in
the model, and resolves transport around them better than other 1-line models for a long simulation period
(USACE, 2014).
[Q]APPENDIX B
Numerical Modeling Technical Report
This appendix presents the technical inputs and findings from the numerical modeling of Project alternatives.
1.Model Selection
The numerical model chosen to evaluate the effectiveness of each concept option was the Littoral Processes
and Coastline Kinetics (LITPACK),part ofthe MIKE suite of modeling applications developed by Delft Hydraulic
Institute (DHI).LITPACK is designed to model long term shoreline evolution for the purpose of optimizing and
evaluating the design and development of coastal works.This model is regularly updated,and the most recent
version (2020)is used for the project.The model is known as a 1-contour line model and requires that the
beach profile shape remains relatively constant as is moves seaward or shoreward seasonally so that change
in beach volume is directly related to shoreline change (USACE,2014).The model couples hydrodynamic and
sediment transport models to calculate littoral drift rates and the coastline position across the model domain
over the simulation period.
To assess long term effects of sediment movement effectively for this project,a model that could resolve
transport and hydrodynamic conditions around offshore and nearshore structures such as groins and detached
breakwaters was needed.LITPACK allows for offshore breakwaters,groins,and revetments to be included in
the model,and resolves transport around them better than other 1-line models for a long simulation period
(USACE,2014).
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GHD | City of Oceanside Beach Sand Replenishment and Retention Device Project| Page 2
1. Introduction
A numerical model was developed to aide in the selection of a preferred beach nourishment and sand retention
alternative for the City of Oceanside. A primary objective of the modeling effort was to evaluate the ability of
sand retention structures to retain and prolong the performance of beach fills. The 2012 Regional Sand Beach
Project II (RSBP II) nourishments that occurred in Oceanside and Carlsbad were used to validate the model
and evaluate effectiveness of sand retention structures. Using site-specific data, the integrated hydrodynamic,
wave and sediment transport model was set up to encompass the entire Project Area and nearshore
environment. Using the coupled model, multiple configurations of groins and artificial reefs were simulated.
1.1 Challenges with Modeling Shoreline Morphology
Numerical modeling of shoreline morphology is imprecise because of the difficultly of mathematically
describing the complicated dynamics of coastal processes. Modern computing power does not have the ability
to resolve the fundamental physics behind coastal processes, and thus approximations are made for nearshore
sediment dynamics based on broad and consequential assumptions like the 1-contour line model. While
regions like the Project area can fit those assumptions reasonably well, inherent error in coastal modeling
remains. The results of this model are intended to provide generalized long-term trends of accretion or erosion
across the project area, not precise site-specific shoreline movement. The results of this model are one of
many factors that will be considered in selecting the preferred sand retention system.
Successful shoreline modeling requires a robust model with highly accurate site-specific data that can capture
the effects of a highly dynamic and variable area. California is also a highly complex and energetic coastline
that has proved historically difficult to model due to lack of precise site-specific longshore transport values. The
majority of California’s coastline is characterized by significant bi-directional longshore transport in response
to a seasonal wave climate. Numerical models applied to California’s coastline have been employed at various
locations with limited accuracy due to the challenges previously discussed.
A scaled 1:100 physical model of Oceanside was built and tested in 1980 by the USACE to study shoaling and
wave conditions with sand retention devices installed in the model (USACE, 1980). While the model was
meticulously created to mimic the conditions at Oceanside, it was unable to fully capture the entirety of the
systems’ complexities and its results were presented as general outcomes. The approach taken to the task of
validating and running the LITPACK model over the Project shoreline is to come as close as possible to the
physical conditions in the Project area while recognizing the inherent limitations of the model. The results
presented in this report should be used only as one of many tools in choosing a preferred design option to
move forward with.
1.2 Model Domain
The model domain stretches from the Southern side of the Oceanside Harbor to the Agua Hedionda Lagoon
north jetty as shown in Figure 1. This encapsulates the entire project area and is limited by the model’s ability
to simulate the effects of the Harbor.
1 .Introduction
A numerical model was developed to aide in the selection of a preferred beach nourishment and sand retention
alternative for the City of Oceanside.A primary objective of the modeling effort was to evaluate the ability of
sand retention structures to retain and prolong the performance of beach fills.The 2012 Regional Sand Beach
Project II (RSBP ll)nourishments that occurred in Oceanside and Carlsbad were used to validate the model
and evaluate effectiveness of sand retention structures.Using site-specific data,the integrated hydrodynamic,
wave and sediment transport model was set up to encompass the entire Project Area and nearshore
environment.Using the coupled model,multiple configurations of groins and artificial reefs were simulated.
1.1 Challenges with Modeling Shoreline Morphology
Numerical modeling of shoreline morphology is imprecise because of the difficultly of mathematically
describing the complicated dynamics of coastal processes.Modern computing power does not have the ability
to resolve the fundamental physics behind coastal processes,and thus approximations are made for nearshore
sediment dynamics based on broad and consequential assumptions like the 1-contour line model.While
regions like the Project area can fit those assumptions reasonably well,inherent error in coastal modeling
remains.The results of this model are intended to provide generalized long-term trends of accretion or erosion
across the project area,not precise site-specific shoreline movement.The results of this model are one of
many factors that will be considered in selecting the preferred sand retention system.
Successful shoreline modeling requires a robust model with highly accurate site-specific data that can capture
the effects of a highly dynamic and variable area.California is also a highly complex and energetic coastline
that has proved historically difficult to model due to lack of precise site-specific longshore transport values.The
majority of California’s coastline is characterized by significant bi-directional longshore transport in response
to a seasonal wave climate.Numerical models applied to California’s coastline have been employed at various
locations with limited accuracy due to the challenges previously discussed.
A scaled 1:100 physical model of Oceanside was built and tested in 1980 by the USACE to study shoaling and
wave conditions with sand retention devices installed in the model (USACE,1980).While the model was
meticulously created to mimic the conditions at Oceanside,it was unable to fully capture the entirety of the
systems’complexities and its results were presented as general outcomes.The approach taken to the task of
validating and running the LlTPACK model over the Project shoreline is to come as close as possible to the
physical conditions in the Project area while recognizing the inherent limitations of the model.The results
presented in this report should be used only as one of many tools in choosing a preferred design option to
move fonNard with.
1.2 Model Domain
The model domain stretches from the Southern side of the Oceanside Harbor to the Agua Hedionda Lagoon
north jetty as shown in Figure 1.This encapsulates the entire project area and is limited by the model’s ability
to simulate the effects of the Harbor.
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Jan. 4, 2022 Item 4 Page 140 of 229
GHD | City of Oceanside Beach Sand Replenishment and Retention Device Project| Page 3
Figure 1 Project and Model Domain Area
Approximate ModelI:|
Contour (NAVD88)10'
M;Frugal:LiriertCMkln’fllCallieHw'zallilflalillr Mm199:mmmmmmwProject and Model Domain AreaFigure1
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2. Model Setup
2.1 Waves
LITPACK allows for waves measured in deep water to be used in the model. LITPACK computes a wave
transformation to the nearshore internally, provided the coastline is relatively straight and the offshore contours
are quasi-parallel. For this model, the Coastal Data Information Program’s (CDIP) offshore wave buoy data
was used. The Oceanside buoy (Station 045) is located at a water depth of 238 m (780ft) and provides a
continuous measured dataset from May 1997 through to present day. Another potential source of wave data
is the Wave Information Studies (WIS) hindcast dataset provided by the USACE. The locations of both stations
are shown in Figure 2. There are some differences between the wave directions of these two data sources;
WIS data suggests that waves coming from the west are more frequent, while CDIP has recorded that swells
from the southwest are more common. The team chose to use the CDIP data set for the model over the WIS
hindcast data as it measures waves in real time and is closer to the project shoreline as shown in Figure 2.
The CDIP dataset contains mean wave direction, peak wave period, and significant wave height every thirty
minutes. The dataset contains holes of hours or days interspersed within the dataset where maintenance work
was done, or data was not recorded. To resolve the larger data gaps, missing values were averaged to the
nearest neighbor, which is acceptable as the typical long period swells on the west coast take many hours or
days to decay as they originate far from the coastline. Discrete isolated data gaps over the course of the years
of data used were deemed too small to affect the long-term sediment transport rates, as the seasonal changes
were still captured, and only small portions of swell events were excluded from the data. A wave rose for CDIP
Station 045 over the simulation period is shown below in Figure 3.
The waves internally transformed by LITPACK to the nearshore are treated as a representative wave climate
for the model domain, which is appropriate due to the project area’s straight coastline and nearshore parallel
bathymetry contours. This provides for the wave climate being relatively homogenous across the project area.
2.Model Setup
2.1 Waves
LITPACK allows for waves measured in deep water to be used in the model.LITPACK computes a wave
transformation to the nearshore internally,provided the coastline is relatively straight and the offshore contours
are quasi-parallel.For this model,the Coastal Data Information Program’s (CDIP)offshore wave buoy data
was used.The Oceanside buoy (Station 045)is located at a water depth of 238 m (780ft)and provides a
continuous measured dataset from May 1997 through to present day.Another potential source of wave data
is the Wave Information Studies (WIS)hindcast dataset provided by the USACE.The locations of both stations
are shown in Figure 2.There are some differences between the wave directions of these two data sources;
WIS data suggests that waves coming from the west are more frequent,while CDIP has recorded that swells
from the southwest are more common.The team chose to use the CDIP data set for the model over the WIS
hindcast data as it measures waves in real time and is closer to the project shoreline as shown in Figure 2.
The CDIP dataset contains mean wave direction,peak wave period,and significant wave height every thirty
minutes.The dataset contains holes of hours or days interspersed within the dataset where maintenance work
was done,or data was not recorded.To resolve the larger data gaps,missing values were averaged to the
nearest neighbor,which is acceptable as the typical long period swells on the west coast take many hours or
days to decay as they originate far from the coastline.Discrete isolated data gaps over the course of the years
of data used were deemed too small to affect the long-term sediment transport rates,as the seasonal changes
were still captured,and only small portions of swell events were excluded from the data.A wave rose for CDIP
Station 045 over the simulation period is shown below in Figure 3.
The waves internally transformed by LITPACK to the nearshore are treated as a representative wave climate
for the model domain,which is appropriate due to the project area’s straight coastline and nearshore parallel
bathymetry contours.This provides for the wave climate being relatively homogenous across the project area.
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Jan. 4, 2022 Item 4 Page 142 of 229
GHD | City of Oceanside Beach Sand Replenishment and Retention Device Project| Page 5
Figure 2 Offshore wave buoys and project area
Legend
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D Offshore OceanSIde (045:
Project Shorehne
2.75 5.5 N
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MapProjeqim:Mel’camrAuxllarySphere ..‘u E3.fl _oFAD:H Damn:was193!mm 1&1".W WCoordinatemmzwes19MWeouemAuxi'aySphere mwmmuse?“
Figure 2 Offshore wave buoys and project area
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GHD | City of Oceanside Beach Sand Replenishment and Retention Device Project| Page 6
Figure 3 CDIP Station 045 Wave Rose for Model Simulation Period 2012-2016
2.2 Water Levels
Water levels were described by a six-minute interval time series of tide data pulled from the La Jolla tide buoy,
NOAA Station #9410230, shown in Figure 2. The water levels do not vary significantly between the project
area and the buoy and are assumed to be constant over the project domain. All water levels use North
American Vertical Datum of 1988 (NAVD88) as their datum to be consistent with all other spatially referenced
data used.
2.3 Bathymetry
The model relies on nearshore bathymetry data to calculate hydrodynamic conditions and longshore sediment
transport rates (DHI 2020) along the study area. Beach profile shape and shoreline orientation are the primary
factors used to describe nearshore bathymetry.
2.3.1 Beach Profiles
Nearshore bathymetry profiles perpendicular to the coast were specified for areas of significant erosion and
accretion according to historical shoreline positions. Bathymetry profiles were extracted from a topobathy
digital elevation model (DEM) created from lidar and imagery datasets by the California Coastal Conservancy
collected from 2009 to 2011. The vertical and horizontal accuracy were reported to be 15 and 300 cm;
Station 045 0 2012101“”-201 5’1 2’31WaveRose225Records:69987
801SignficantWaveHeight(ft)
0 3 6 9 12 15 18 21 24 27 30 33
Figure 3 CDIP Station 045 Wave Rose for Model Simulation Period 2012-2016
2.2 Water Levels
Water levels were described by a six-minute interval time series of tide data pulled from the La Jolla tide buoy,
NOAA Station #9410230,shown in Figure 2.The water levels do not vary significantly between the project
area and the buoy and are assumed to be constant over the project domain.All water levels use North
American Vertical Datum of 1988 (NAVD88)as their datum to be consistent with all other spatially referenced
data used.
2.3 Bathymetry
The model relies on nearshore bathymetry data to calculate hydrodynamic conditions and longshore sediment
transport rates (DHI 2020)along the study area.Beach profile shape and shoreline orientation are the primary
factors used to describe nearshore bathymetry.
2.3.1 Beach Profiles
Nearshore bathymetry profiles perpendicular to the coast were specified for areas of significant erosion and
accretion according to historical shoreline positions.Bathymetry profiles were extracted from a topobathy
digital elevation model (DEM)created from Iidar and imagery datasets by the California Coastal Conservancy
collected from 2009 to 2011.The vertical and horizontal accuracy were reported to be 15 and 300 cm;
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Jan. 4, 2022 Item 4 Page 144 of 229
GHD | City of Oceanside Beach Sand Replenishment and Retention Device Project| Page 7
respectively. The vertical datum used was NAVD88. The profiles extend seaward to 150 feet of depth, and
landward to around +12 feet NAVD88 at a 5 ft resolution. 150 feet of depth corresponds to intermediate depth
for the largest waves in the simulation time, where refraction begins to occur. The extracted data was smoothed
using a moving average to minimize model error in sediment transport and refraction due to sudden profile
changes. Profiles were taken out to the intermediate depths for the largest waves during the simulation time
so that the model could accurately refract waves to the coast from deep water. The angle at which the profiles
were set was taken as perpendicular from the traced shoreline. A figure of the profile locations is shown below
in Figure 5. The profile angles and orientation definition as defined by the LITPACK User Manual (DHI 2020)
are shown below in Figure 6 and Table 3.1. Figure 8 shows the profiles’ position along the coastline.
Figure 4 Definition of Coastline orientation 𝜶𝜶𝟎𝟎 and cross-shore profile alignment (DHI
2020)
Table 1.1. Bathymetry Profile Angles
Profile Number Profile Angle 𝛼𝛼0 (clockwise from True North)
Profile 1 238.38
Profile 2 237.38
Profile 3 236.37
Profile 4 235.37
Profile 5 235.37
Profile 6 234.36
Profile 7 234.36
Profile 8 233.35
respectively.The vertical datum used was NAVD88.The profiles extend seaward to 150 feet of depth,and
landward to around +12 feet NAVD88 at a 5 ft resolution.150 feet of depth corresponds to intermediate depth
forthe largestwaves in the simulation time,where refraction begins to occur.The extracted data was smoothed
using a moving average to minimize model error in sediment transport and refraction due to sudden profile
changes.Profiles were taken out to the intermediate depths for the largest waves during the simulation time
so that the model could accurately refract waves to the coast from deep water.The angle at which the profiles
were set was taken as perpendicular from the traced shoreline.A figure of the profile locations is shown below
in Figure 5.The profile angles and orientation definition as defined by the LITPACK User Manual (DHI 2020)
are shown below in Figure 6 and Table 3.1.Figure 8 shows the profiles’position along the coastline.
N
Figure 4 Definition of Coastline orientation a0 and cross-shore profile alignment (DHI
2020)
Table 1.1.Bathymetry Profile Angles
Profile Number Profile Angle a0 (clockwise
from True North)
Profile 1 238.38
Profile 2 237.38
Profile 3 236.37
Profile 4 235.37
Profile 5 235.37
Profile 6 234.36
Profile 7 234.36
Profile 8 233.35
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2.3.2 Shoreline Baseline
The coastline in LITPACK is specified in relation to a baseline which has a fixed position and orientation. The
shoreline position is then described as a series of perpendicular distances from the baseline. The baseline
must be near shore-parallel to the coastline’s general orientation as shown in Figure 7 (DHI 2020).
The shoreline used in the model was traced in ArcMap using historical imagery pulled from the NOAA Data
Access Viewer. Several shoreline years were traced to understand erosional and accretional patterns in the
study area. The 8/23/2010 shoreline year was chosen as the start of the simulation for a number of reasons,
but most notably its position in relation to two large scale regional beach nourishment projects. The sediment
from the 2001 RSBP beach nourishment had eroded away, and the RSBP II project was set to begin in the
Fall and Winter of 2012. This is described in further detail in Section 4. Once traced, the shoreline was brought
into MIKE Zero’s bathymetry editor to extract perpendicular distances from a set baseline, shown in Figure 8.
Figure 5 LITPACK definition of a shoreline position (DHI 2020)
2.3.2 Shoreline Baseline
The coastline in LITPACK is specified in relation to a baseline which has a fixed position and orientation.The
shoreline position is then described as a series of perpendicular distances from the baseline.The baseline
must be near shore-parallel to the coastline’s general orientation as shown in Figure 7 (DHI 2020).
The shoreline used in the model was traced in ArcMap using historical imagery pulled from the NOAA Data
Access Viewer.Several shoreline years were traced to understand erosional and accretional patterns in the
study area.The 8/23/2010 shoreline year was chosen as the start of the simulation for a number of reasons,
but most notably its position in relation to two large scale regional beach nourishment projects.The sediment
from the 2001 RSBP beach nourishment had eroded away,and the RSBP II project was set to begin in the
Fall and Winter of 2012.This is described in further detail in Section 4.Once traced,the shoreline was brought
into MIKE Zero’s bathymetry editor to extract perpendicular distances from a set baseline,shown in Figure 8.
Figure 5 LITPACK definition of a shoreline position (DHI 2020)
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Jan. 4, 2022 Item 4 Page 146 of 229
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Figure 6 Coastline and beach profile position relative to baseline
2.4 Sediment
2.4.1 Sediment Properties
The median grain diameter (D50) of the sediment varies along the cross-shore profiles in the project area, with
larger diameters (~0.5 mm) found close to shore and finer grained (~0.1 mm) sand deposited near the depth
of closure (USACE 2018). Grain size is assumed to remain relatively constant over time as the wave climate
and sand sources have not changed over the past decade, so there is no major mechanism to change the
gradation in the nearshore. The grain size varies slightly over the longshore and that is reflected in the data as
the USACE sampled in 2018 at multiple transects in the project area. This was also shown in the Moffat &
Nichol Sampling Analysis Plan Results Report (M&N 2016). The results of this are shown in Table 3.2 and
Figure 6. The sediment sampling done by the USACE and M&N showed the sediment to be poorly graded/well
sorted, and thus the sediment was defined as uniform sand for each point along the profile.
617000 _
6160005
615000 E
614000 {
6130005
612000 f
E Bathymetry611000:-BaselineI|:|Coastline610000:-32=7_6609000:-5:=4-3600000:-2
:-1
$71“)-I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I E Undefinw Valle1692000 1694000 1896000 1898000 1900000["1]
Figure 6 Coastline and beach profile position relative to baseline
2.4 Sediment
2.4.1 Sediment Properties
The median grain diameter (D50)of the sediment varies along the cross-shore profiles in the project area,with
larger diameters (~0.5 mm)found close to shore and finer grained (~O.1 mm)sand deposited near the depth
of closure (USACE 2018).Grain size is assumed to remain relatively constant over time as the wave climate
and sand sources have not changed over the past decade,so there is no major mechanism to change the
gradation in the nearshore.The grain size varies slightly over the longshore and that is reflected in the data as
the USACE sampled in 2018 at multiple transects in the project area.This was also shown in the Moffat &
Nichol Sampling Analysis Plan Results Report (M&N 2016).The results of this are shown in Table 3.2 and
Figure 6.The sediment sampling done by the USACE and M&N showed the sediment to be poorly graded/well
sorted,and thus the sediment was defined as uniform sand for each point along the profile.
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GHD | City of Oceanside Beach Sand Replenishment and Retention Device Project| Page 10
Table 3.2. Oceanside Sediment Characteristics (M&N, 2016)
Reach
Sediment
Characteristics A B C D E F G Santa
Margarita
D50 Range (mm) 0.1 to
0.5
0.1 to
0.4
0.1 to
0.3
0.1 to
0.3
0.1 to
0.2
0.1 to
0.2
0.1 to
0.2 0.1 to 0.2
% Fines 0.6 to
54.7
0.7 to
64.2
0.4 to
67.6
0.4 to
73.3
0.7 to
79.6
1.2 to
53.9
1.4 to
78.9 1.0 to 77.7
Figure 7 2016 SAPR Shoreline Reaches (M&N, 2016)
2.4.2 Bed Parameters
Bed parameters describe the processes near the bed (DHI 2020) such as porosity ripples, critical shield’s
parameter, and inertial coefficients. These were left as default values as they covered the range of sediment
properties in the project area.
Table 3.2.Oceanside Sediment Characteristics (M&N,2016)
Sediment Santa
0.1 to 0.1 to 0.1 to 0.1 to 0.1 to 0.1 to 0.1 to 0.1 to 0.2D50Range(mm)0.5 0.4 0.3 0.3 0.2 0.2 0.2
.0.6 to 0.7 to 0.4 to 0.4 to 0.7 to 1.2 to 1.4 to0A’fines 54.7 64.2 67.6 73.3 79.6 53.9 78.9 1'0 t°77'7
StudyReaches
Reacrm
“each 5”each 6
Ranch 0
.Reach E
Reach F
Ranch (3mmm MA‘I 1.250 2.500 5.000Fec-5....Hum-I-n-u-mh-n'nlIRI-M.“.muq—w-Ammufiu...“
Figure 7 2016 SAPR Shoreline Reaches (M&N,2016)
2.4.2 Bed Parameters
Bed parameters describe the processes near the bed (DHI 2020)such as porosity ripples,critical shield's
parameter,and inertial coefficients.These were left as default values as they covered the range of sediment
properties in the project area.
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GHD | City of Oceanside Beach Sand Replenishment and Retention Device Project| Page 11
3. Model Validation
Validation of a model is an important step to evaluate the model’s ability to simulate observed shoreline
changes. Validating a model is achieved by running a simulation of a past event and comparing the results to
existing measured data of the same event with the purpose of verifying that the model can reasonably predict
outcomes of future events. Once the validation model is set up and run, calibration of the input parameters
may be needed to align the validation results to the measured results.
3.1 Calibrating Littoral Drift
Littoral drift rates across the project area were calibrated to get within the range of values displayed below in
Table 4.1. The values shown in the table were not measured specifically in the project area domain, but rather
for the whole littoral cell, which spans 60 miles (Patsch & Griggs, 2006). The large range and uncertainty
associated with measured and estimated littoral drift rates necessitated an iterative approach to calibrating the
model. A set of parameters would be run, and the model shoreline would be compared to the measured
shoreline, at which point the parameters would be reassessed and rerun.
Table 4.1. Longshore Sediment Transport Estimates
Location Net Drift Direction Source
Oceanside Littoral Cell
146,000 South Patsch & Griggs, 2006
254,000 South Inman & Jenkins (1983)
102,000 South Hales (1978)
175,000 South USACE, 2016
215,000 South Marine Advisors (1961)
250,000 South Inman (1976)
194,000 South Hales (1979); Inman & Jenkins (1985); Dolan et al. (1987)
Oceanside Harbor Southside 106,000 South USACE, (1991); Tekmarine, Inc., (1978)
The coastline orientation was also calibrated for each profile to test sensitivity of the model to this parameter
and get accurate transport rates. Because the mean wave direction was 228 degrees, and the coastline is
nearly perpendicular to this direction, the sediment transport rate and direction were highly dependent on the
coastline orientation. The profile orientations (measured clockwise in degrees from True North) ranged from
239 degrees on the southern end of the project area to 233 degrees on the northern end. The differences in
coastline orientation caused an increase of net southern transport from the northern to the southern end of the
project area. The model predicted longshore net transport rates of 68,000 cubic yards per year (cyy) on the
Northern end of the project area to 130,000 cyy on the southern end.
3.2 Validating Model
The shoreline changes due to the 2012 Regional Sand Beach Project II (RSBP II) were used validate the
model. RSBP II was a sand replenishment project that delivered sand to select beaches in San Diego county.
Oceanside received a total of 293,000 cubic yards from 10/05/2012 to 10/20/2012 distributed from Buccaneer
3.Model Validation
Validation of a model is an important step to evaluate the model’s ability to simulate observed shoreline
changes.Validating a model is achieved by running a simulation of a past event and comparing the results to
existing measured data of the same event with the purpose of verifying that the model can reasonably predict
outcomes of future events.Once the validation model is set up and run,calibration of the input parameters
may be needed to align the validation results to the measured results.
3.1 Calibrating Littoral Drift
Littoral drift rates across the project area were calibrated to get within the range of values displayed below in
Table 4.1.The values shown in the table were not measured specifically in the project area domain,but rather
for the whole littoral cell,which spans 60 miles (Patsch &Griggs,2006).The large range and uncertainty
associated with measured and estimated littoral drift rates necessitated an iterative approach to calibrating the
model.A set of parameters would be run,and the model shoreline would be compared to the measured
shoreline,at which point the parameters would be reassessed and rerun.
Table 4.1.Longshore Sediment Transport Estimates
146,000 South Patsch &Griggs,2006
254,000 South lnman &Jenkins (1983)
102,000 South Hales (1978)
Oceanside Littoral Cell 175’000 SOUth USACE’2016215,000 South Marine Advisors (1961)
250,000 South lnman (1976)
South Hales (1979);lnman &Jenkins (1985);194'000 Dolan et al.(1987)
oceanf'de Ham”106,000 S°Uth USACE,(1991);Tekmarine,Inc.,(1978)Southsrde
The coastline orientation was also calibrated for each profile to test sensitivity of the model to this parameter
and get accurate transport rates.Because the mean wave direction was 228 degrees,and the coastline is
nearly perpendicular to this direction,the sediment transport rate and direction were highly dependent on the
coastline orientation.The profile orientations (measured clockwise in degrees from True North)ranged from
239 degrees on the southern end of the project area to 233 degrees on the northern end.The differences in
coastline orientation caused an increase of net southern transport from the northern to the southern end of the
project area.The model predicted longshore net transport rates of 68,000 cubic yards per year (cyy)on the
Northern end of the project area to 130,000 cyy on the southern end.
3.2 Validating Model
The shoreline changes due to the 2012 Regional Sand Beach Project II (RSBP II)were used validate the
model.RSBP II was a sand replenishment project that delivered sand to select beaches in San Diego county.
Oceanside received a total of 293,000 cubic yards from 10/05/2012 to 10/20/2012 distributed from Buccaneer
GHD |City of Oceanside Beach Sand Replenishment and Retention Device Projectl Page 11
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GHD | City of Oceanside Beach Sand Replenishment and Retention Device Project| Page 12
Beach to Hayes Street. North Carlsbad received 218,000 cubic yards from 11/24/2012 to 12/07/2013
distributed from the Buena Vista Lagoon mouth to Carlsbad Village Drive (SANDAG 2012) as shown in Figures
10 and 11. Using georeferenced aerial imagery, it was verified that the RSBP II sand stayed within the project
area until about 2016 as shown in Figure 11. The same period was modeled in the simulation to try and match
the general trends of erosion and accretion within the project area with the measured trends. The LITPACK
model simulation starts on January 1st, 2012 and runs until March 22nd, 2016.
The measured shoreline change shows accretion along the southern end of the project shoreline, Reach E in
Figure 12. From Reach D until the southern half of Reach A the shoreline is largely erosional. The northern
half of Reach A is accretional.
The LITPACK model was run using the calibrated littoral drift rates and simulated sand sources at the same
rates and locations as the RSPB II beach fill. The LITPACK model shows accretion from the Northern half of
Reach E to Reach B. This is due to the RSBP II fill in the LITPACK model eroding much slower than the
measured shorelines show. To improve agreement with the measured shoreline, the LITPACK model
parameters were recalibrated with the following changes shown in Table 4.2 below.
Figure 8 2012-2016 Measured Shoreline Positions and RSBP II Fill Locations
Beach to Hayes Street.North Carlsbad received 218,000 cubic yards from 11/24/2012 to 12/07/2013
distributed from the Buena Vista Lagoon mouth to Carlsbad Village Drive (SANDAG 2012)as shown in Figures
10 and 11.Using georeferenced aerial imagery,it was verified that the RSBP ||sand stayed within the project
area until about 2016 as shown in Figure 11.The same period was modeled in the simulation to try and match
the general trends of erosion and accretion within the project area with the measured trends.The LlTPACK
model simulation starts on January 15*,2012 and runs until March 22nd,2016.
The measured shoreline change shows accretion along the southern end of the project shoreline,Reach E in
Figure 12.From Reach D until the southern half of Reach A the shoreline is largely erosional.The northern
half of Reach A is accretional.
The LlTPACK model was run using the calibrated littoral drift rates and simulated sand sources at the same
rates and locations as the RSPB ||beach fill.The LlTPACK model shows accretion from the Northern half of
Reach E to Reach B.This is due to the RSBP ||fill in the LlTPACK model eroding much slower than the
measured shorelines show.To improve agreement with the measured shoreline,the LlTPACK model
parameters were recalibrated with the following changes shown in Table 4.2 below.
2012-2016 Shoreline Positions 120
Pier LR HarborlOceansideFill —-77 ~100No 5
.CCarlsF111Lso3H'7:so a
0.E40T]
I-2~20 01
BV Lagoo D
350 300 250 200 150 100 50 0
Transectat
—2012 —2014 —2016 —Harbor —SLRGroin —Pier
Figure 8 2012-2016 Measured Shoreline Positions and RSBP II Fill Locations
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Figure 9 Nourishment Only Scenario: Shoreline Change and Position
Modeled vs.Measured Shoreline Change:NOS800
—MeasuredShoreline 31‘2016
A400_—ModeledShoreline -Nourishment OnlySoena‘-o 1/2014
f —ModeledShoreline -Nourishment Only 1/2015
:2 —ModeledShoreline -Nourishment OnlyScene'0 3/2016toOD.200-Er:5_Ito.5LL
Reach A
200 \0.00 1.06 2.13 3.19 4.25 5.3CrossShoreDistance(Miles)
Legend
Nourishment Only Scenario 3/2016
—Initial Position Shoreline
.WEE “its l-5!:THE STRANDN‘
“‘.V'‘>—,is 9003::_S .2 NPAClFIC st;.;.5..g gt w;P g .~"'E ''9 \5 § 3 we“?‘é -é?:Wm“.x-..—fi :55-~0'——————a —-BuenhVi‘sQa—"i 7"‘'tempemaaigomwmr it":I w la!.‘L ».‘r s '
’1w "I it.(mast MONTST i '60 'E g '1‘'"I l!i.RF 0 ,‘9 m .,.1 ...73W 0 u ,1..m(smms ,_VlSTADELmG‘,\8 o Hlseg)‘x 'w MARWAV #w _g S i ‘7 ,4BREW‘ST .5 ,_FREEMANST .lg »'g'xALVABAPOSTlS on SW ‘0 MITCHELLST ..-5 m m 3w.~~-5.a e >o.MMQIS fig 3,;a,.gg,:.§nj‘
'".1,,‘V .»_......,_.3“mama-m".»News.7 g 1 E ‘mmuumunmmuinsmm A CLEMENYINE ST ,5/1 2 ‘n k(
~-’"r,A ;-__3.
Figure 9 Nourishment Only Scenario:Shoreline Change and Position
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Table 4.1 List of parameters changed to improve validation
Parameter Notes
Bathymetry - Profiles extended from 50 to 150 ft depth - Shoreline resolution increased from 25 to 10 meters - Profile 4 used as representative bathymetry profile
- Smoothed bathymetry using a moving average
Sediment Data - Sediment data for Profile 4 used as representative sediment
distribution
Wave Data - Waves internally transformed to 150 ft depth
Structures - San Luis Rey groin and Agua Hedionda jetties excluded from model
- Shoreline protection / Rock revetment resolution increased to 50 points
Baseline Shoreline Position - Increased resolution from 25 meters to 10 meters - Smoothed initial coastline using a moving average
The difficulty in obtaining well validated results with the LITPACK model came from two main sources: the
errors associated with simplifying a complex region down to a 1-line model, and the uncertainty of the available
data describing the project area. The historical source of erosion in the project area is the lack of sediment in
the local littoral cell due to updrift impoundment by the Oceanside Harbor. The model is incapable of resolving
the complicated dynamics of the harbor structures and their effect on sediment supply. The LITPACK model
assumes that the sediment supply is infinite (DHI 2020), resulting in a relatively balanced sediment budget
within the model domain and a more stable shoreline than the actual shoreline.
As described in the previous section, the uncertainty in local littoral transport rates that the model was
calibrated to is a probable source of error. The 100,000 cubic yard per year range in the net longshore transport
estimates is significant and will affect how the model simulates shoreline change.
The boundaries of the model domain proved difficult to model. The model shoreline is bounded by the harbor
to the north and the Agua Hedionda Jetties to the south. Because those structures were not included in the
model, the modeled shoreline behaves differently than the measured results and predicts erosion on both ends
of the domain. As such, the model was calibrated to best reflect measured conditions within the vicinity of the
project study area, from Tyson Street to Buena Vista Lagoon. The model-predicted longshore transport within
this region increases from 88,000 cyy to 114,000 cyy from Tyson Street to the Buena Vista Lagoon respectively
as shown in Figure 10 and was considered appropriate for the purposes of this study.
Table 4.1 List of parameters changed to improve validation
Bathymetry -Profiles extended from 50 to 150 ft depth
-Shoreline resolution increased from 25 to 10 meters
-Profile 4 used as representative bathymetry profile
-Smoothed bathymetry using a moving average
Sediment Data -Sediment data for Profile 4 used as representative sediment
distribution
Wave Data -Waves internally transformed to 150 ft depth
Structures -San Luis Rey groin and Agua Hedionda jetties excluded from
model
-Shoreline protection /Rock revetment resolution increased to 50
points
Baseline Shoreline -Increased resolution from 25 meters to 10 meters
Position -Smoothed initial coastline using a moving average
The difficulty in obtaining well validated results with the LITPACK model came from two main sources:the
errors associated with simplifying a complex region down to a 1-line model,and the uncertainty of the available
data describing the project area.The historical source of erosion in the project area is the lack of sediment in
the local littoral cell due to updrift impoundment by the Oceanside Harbor.The model is incapable of resolving
the complicated dynamics of the harbor structures and their effect on sediment supply.The LITPACK model
assumes that the sediment supply is infinite (DHI 2020),resulting in a relatively balanced sediment budget
within the model domain and a more stable shoreline than the actual shoreline.
As described in the previous section,the uncertainty in local littoral transport rates that the model was
calibrated to is a probable source of error.The 100,000 cubic yard per year range in the net longshore transport
estimates is significant and will affect how the model simulates shoreline change.
The boundaries of the model domain proved difficult to model.The model shoreline is bounded by the harbor
to the north and the Agua Hedionda Jetties to the south.Because those structures were not included in the
model,the modeled shoreline behaves differently than the measured results and predicts erosion on both ends
of the domain.As such,the model was calibrated to best refiect measured conditions within the vicinity of the
project study area,from Tyson Street to Buena Vista Lagoon.The model-predicted longshore transport within
this region increases from 88,000 cyy to 114,000 cyy from Tyson Street to the Buena Vista Lagoon respectively
as shown in Figure 10 and was considered appropriate for the purposes of this study.
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4. LITPACK Sand Retention Device Modeling
In accordance with the scope of services, multiple scenarios were modeled: one “Nourishment Only Scenario”
(NOS) that doubled as the model validation, and two sand retention configurations representing groins and
artificial reefs. The NOS functions as an assessment of the efficacy of a sand replenishment project alone with
the same volume and placement location of the RSBP II. The modeled sand retention devices were simulated
using the same data as the NOS so that the model results could be compared to the NOS’s results. The sand
retention devices were modeled with the same volume of sand as RBSP II, but the placement locations were
modified to reduce downdrift impacts. The sand retention devices modeled were a groin field and artificial reef
field respectively. As the purpose of this study is to recommend an implementable pilot project, the full groin
and artificial reef layouts stretching from Tyson Street to Buena Vista Lagoon were narrowed down to pilot
projects and modeled separately. The position, sizing and model results of the sand retention devices are
described in the sections that follow.
The only existing structure that was included in the model was the section of the revetment that would be
fronted by the sand retention devices. From Tyson Street to Buena Vista Lagoon the model treats the shoreline
as nonerodable. The geospatial position of the revetment was extracted in ArcMap. Although the entire
backshore is armored and can be treated as non-erodible, only the subsection fronting the sand retention
devices was included. This was done to examine the potential extents of shoreline change updrift and downdrift
of the sand retention systems.
4.1 Scenario 1: Full Groin Field Layout
4.1.1 Modeling Approach
The modeled groin field layout was designed using guidance from the 1980 U.S. Army Corp of Engineers
(USACE) study, Design of Structures for Harbor Improvement and Beach Erosion Control, which modeled and
tested different layouts of groins in the area using a scaled down 3-dimensional physical model of the harbor
and surrounding beaches. After testing ten different layouts of groin fields, the study found that ten 800-foot-
long groins spaced 1000 feet apart proved to be the most effective at retaining sand. To cover the entire project
area, the groin layout for the purposes of this study was comprised of twelve 600-foot-long groins spaced at
around 1000 feet. This placement and spacing combined the USACE study findings with guidance on length
to spacing ratios described in the Coastal Engineering Manual (USACE, 2006). The 600-foot length considers
the prefill beach width to be 100 feet, resulting in an active groin length of 500 feet. There is some variation in
spacing of the groins because they were placed at street ends or areas that would not inhibit public beach
access.
The two southernmost groins were tapered to 400 feet and 300 feet long respectively to mitigate downdrift
impacts based on findings from the USACE’s physical modeling study (1980). The southernmost groins were
tapered as the net longshore transport direction is south and more sediment will be able to bypass the groin
system to continue downdrift of the structures to mitigate erosional effects. The spacing of the last two groins
was kept at 1000 feet after sensitivity tests were run on downdrift effects with 600 and 400 foot spacing
respectively, and no significant differences in retention and downdrift impacts were noticed.
4.LITPACK Sand Retention Device Modeling
In accordance with the scope of services,multiple scenarios were modeled:one “Nourishment Only Scenario”
(NOS)that doubled as the model validation,and two sand retention configurations representing groins and
artificial reefs.The NOS functions as an assessment of the efficacy of a sand replenishment project alone with
the same volume and placement location of the RSBP II.The modeled sand retention devices were simulated
using the same data as the NOS so that the model results could be compared to the NOS’s results.The sand
retention devices were modeled with the same volume of sand as RBSP II,but the placement locations were
modified to reduce downdrift impacts.The sand retention devices modeled were a groin field and artificial reef
field respectively.As the purpose of this study is to recommend an implementable pilot project,the full groin
and artificial reef layouts stretching from Tyson Street to Buena Vista Lagoon were narrowed down to pilot
projects and modeled separately.The position,sizing and model results of the sand retention devices are
described in the sections that follow.
The only existing structure that was included in the model was the section of the revetment that would be
fronted by the sand retention devices.From Tyson Street to Buena Vista Lagoon the model treats the shoreline
as nonerodable.The geospatial position of the revetment was extracted in ArcMap.Although the entire
backshore is armored and can be treated as non-erodible,only the subsection fronting the sand retention
devices was included.This was done to examine the potential extents of shoreline change updrift and downdrift
of the sand retention systems.
4.1 Scenario 1:Full Groin Field Layout
4.1.1 Modeling Approach
The modeled groin field layout was designed using guidance from the 1980 US.Army Corp of Engineers
(USACE)study,Design of Structures for Harbor Improvement and Beach Erosion Control,which modeled and
tested different layouts of groins in the area using a scaled down 3-dimensional physical model of the harbor
and surrounding beaches.After testing ten different layouts of groin fields,the study found that ten 800-foot—
long groins spaced 1000 feet apart proved to be the most effective at retaining sand.To cover the entire project
area,the groin layout for the purposes of this study was comprised of twelve 600—foot—long groins spaced at
around 1000 feet.This placement and spacing combined the USACE study findings with guidance on length
to spacing ratios described in the Coastal Engineering Manual (USACE,2006).The GOO-foot length considers
the prefill beach width to be 100 feet,resulting in an active groin length of 500 feet.There is some variation in
spacing of the groins because they were placed at street ends or areas that would not inhibit public beach
access.
The two southernmost groins were tapered to 400 feet and 300 feet long respectively to mitigate downdrift
impacts based on findings from the USACE’s physical modeling study (1980).The southernmost groins were
tapered as the net longshore transport direction is south and more sediment will be able to bypass the groin
system to continue downdrift of the structures to mitigate erosional effects.The spacing of the last two groins
was kept at 1000 feet after sensitivity tests were run on downdrift effects with 600 and 400 foot spacing
respectively,and no significant differences in retention and downdrift impacts were noticed.
GHD |City of Oceanside Beach Sand Replenishment and Retention Device Projectl Page 15
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GHD | City of Oceanside Beach Sand Replenishment and Retention Device Project| Page 16
The Oceanside RSBP II placement volume of 293,000 cy was used as the prefill placement and was distributed
evenly throughout the groin field. Note that the actual prefilling of a groin field would be much larger, on the
order of 1 million cy to adequately fill the entire 12 groin compartments to the desired 100-foot width. The
Oceanside RBSP II volume was used to be able to compare retention performance of the structures against
the NOS. The result of providing a much smaller prefill than would be needed is a less effective groin field, and
more pronounced downdrift impacts because there is less sand available to bypass the groins. Instead of
starting the prefill at the placement dates of RBSP II, the fill was included at the start of the simulation to
accurately portray how the groin field would operate.
The North Carlsbad RSBP II placement volume of 293,000 cy was used as groin bypass placement amount.
The placement location was optimized through sensitivity tests to provide an adequate level of downdrift
protection. The final placement location used was from the southern limits of the Buena Vista Lagoon outlet to
Pacific Avenue in Carlsbad (approximately 900 feet).
4.1.2 Results and Analysis
The model predicted retention of sand throughout the groin field with accretion of sand in fillets on both sides
of each groin. Although spread over a larger area, the Oceanside prefill stayed in the system and was well
retained by the groins. The model simulation indicated a fairly uniform distribution of sand throughout the groin
field, except for the final year of the simulation in which significant accretion occurs updrift of the northernmost
groin. The results illustrated in the final year are likely due to model limitations and do not reflect a realistic
outcome. The final simulation year (2015-2016) had a more energetic wave climate which increased the
modeled sediment transport rates. Since the model does not simulate the Oceanside Harbor structures and
the groins are modeled as impermeable structures, the amount of accretion predicted upcoast of the groin field
is likely overestimated. In reality a more uniform distribution of sand through the groin system would be
expected, similar to what is observed in groin fields along the southern California coast. A more uniform
distribution of sand throughout the groin system would also lessen the potential for downdrift erosion since
more sand would be moving through the system.
LITPACK reports accumulated volume for each point along the shoreline in its outputs. This is useful for
comparison of the full sand retention buildouts of the groins and the breakwaters to the NOS, as they all have
the same fill volumes. When compared to the accumulated volume of the NOS, the full groin layout retained
175% more sand within the fill placement area based on the 2015 predicted shoreline position.
The Oceanside RSBP ll placement volume of293,000 cy was used as the prefill placement and was distributed
evenly throughout the groin field. Note that the actual prefilling of a groin field would be much larger,on the
order of 1 million cy to adequately fill the entire 12 groin compartments to the desired 100-foot width.The
Oceanside RBSP ll volume was used to be able to compare retention performance of the structures against
the N08.The result of providing a much smaller prefill than would be needed is a less effective groin field,and
more pronounced downdrift impacts because there is less sand available to bypass the groins.Instead of
starting the prefill at the placement dates of RBSP II,the fill was included at the start of the simulation to
accurately portray how the groin field would operate.
The North Carlsbad RSBP ll placement volume of 293,000 cy was used as groin bypass placement amount.
The placement location was optimized through sensitivity tests to provide an adequate level of downdrift
protection.The final placement location used was from the southern limits of the Buena Vista Lagoon outlet to
Pacific Avenue in Carlsbad (approximately 900 feet).
4.1.2 Results and Analysis
The model predicted retention of sand throughout the groin field with accretion of sand in fillets on both sides
of each groin.Although spread over a larger area,the Oceanside prefill stayed in the system and was well
retained by the groins.The model simulation indicated a fairly uniform distribution of sand throughout the groin
field,except for the final year of the simulation in which significant accretion occurs updrift of the northernmost
groin.The results illustrated in the final year are likely due to model limitations and do not reflect a realistic
outcome.The final simulation year (2015-2016)had a more energetic wave climate which increased the
modeled sediment transport rates.Since the model does not simulate the Oceanside Harbor structures and
the groins are modeled as impermeable structures,the amount of accretion predicted upcoast of the groin field
is likely overestimated.In reality a more uniform distribution of sand through the groin system would be
expected,similar to what is observed in groin fields along the southern California coast.A more uniform
distribution of sand throughout the groin system would also lessen the potential for downdrift erosion since
more sand would be moving through the system.
LlTPACK reports accumulated volume for each point along the shoreline in its outputs.This is useful for
comparison of the full sand retention buildouts of the groins and the breakwaters to the NOS,as they all have
the same fill volumes.When compared to the accumulated volume of the NOS,the full groin layout retained
175%more sand within the fill placement area based on the 2015 predicted shoreline position.
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GHD | City of Oceanside Beach Sand Replenishment and Retention Device Project| Page 17
Figure 10 Groin Field: Shoreline Change and Position
4.2 Scenario 2: Groin Field Pilot
4.2.1 Modeling Approach
The groin field pilot was laid out with the goal of showing an effective sand retention project that could be
expanded over time. A series of four groins were modeled to capture the effects in three compartments. The
middle compartment in the four-groin system can be analyzed semi-independently of the boundary effects,
which is why the pilot was not comprised of two or three groins. The boundary compartments invariably will
show changes due solely to being located at the boundaries, whereas the middle compartment is somewhat
shielded from these effects. Retention performance of a larger groin field could be reasonably assessed from
this pilot configuration.
The length and spacing of the groins were the same as the full groin layout, since the goal is that the structures
can remain, if successful, and be expandable to the full groin field discussed above. The downdrift groin in the
pilot was not tapered for this same reason. The pilot groins and downdrift area were prefilled with the same
Modeled Shoreline Change:Groin Layout vs.NOS800I
—ModeledGroin Layout 112014
A400-—ModeledGroin Layout 112015a:.‘E —ModeledGroin Layout312016
:3 —NourishmentOnlyScenario3/2016
0'6:200-Ef:E_vE'u:°'
Reach E ch D Reach C Reach B Reach A
-200 \
0.00 1.06 2.13 3.19 4.25 531CrossShoreDistance(Miles)
Legend
—Groin Crest
—Modeled Groins Shoreline Position 3/2016
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Figure 10 Groin Field:Shoreline Change and Position
4.2 Scenario 2:Groin Field Pilot
4.2.1 Modeling Approach
The groin field pilot was laid out with the goal of showing an effective sand retention project that could be
expanded over time.A series of four groins were modeled to capture the effects in three compartments.The
middle compartment in the four-groin system can be analyzed semi-independently of the boundary effects,
which is why the pilot was not comprised of two or three groins.The boundary compartments invariably will
show changes due solely to being located at the boundaries,whereas the middle compartment is somewhat
shielded from these effects.Retention performance of a larger groin field could be reasonably assessed from
this pilot configuration.
The length and spacing of the groins were the same as the full groin layout,since the goal is that the structures
can remain,if successful,and be expandable to the full groin field discussed above.The downdrift groin in the
pilot was not tapered for this same reason.The pilot groins and downdrift area were prefilled with the same
GHD |City of Oceanside Beach Sand Replenishment and Retention Device Projectl Page 17
Jan. 4, 2022 Item 4 Page 155 of 229
GHD | City of Oceanside Beach Sand Replenishment and Retention Device Project| Page 18
293,000 cy placement volume as the Oceanside fill in RSBP II. The prefill was distributed evenly from Tyson
Street at the northernmost groin to Forster Street just downdrift of the southernmost groin. Of the total prefill
amount, the 3,000-foot-long groin prefill area received 235,000 cy of prefill and the 750 feet of downdrift area
received 58,000 cy of prefill within the model.
4.2.2 Results and Analysis
Like the modeling of the full groin layout, the model predicts uniform retention of sediment throughout the groin
field. The initial fill volume was largely retained within the pilot groin system with accretion of sand in fillets
upcoast of each groin. The beach area retained remained relatively stable throughout the model simulation
with significant increases in beach width in each groin compartment relative to the initial shoreline. Downdrift
erosion was predicted to extend roughly a half mile south of the groin field indicating the importance of a
monitoring and management plan to mitigate these potential impacts.
The model results indicate the pilot configuration would retain a much larger beach area within the initial
placement zone in comparison to a Beach Nourishment only scenario (i.e. RBSP II). The beach width gained
from RBSP II in the original placement area was about 50 feet when averaged over the three-year period
following initial placement. The model results suggest 100-150 feet of beach width gains when averaged over
the model simulation.
While these results are promising, the model limitations must be acknowledged including the inability to
simulate the Oceanside Harbor structures and their influence on sediment supply to the study reach. The
groins are also simulated as impervious structures which may result in more retention than would occur in
reality if these structures are comprised of larger diameter armor stone. These model limitations (infinite supply
of sand and impervious groins) likely result in an overestimate of the beach width retained within the pilot
system. Additional analysis of the groin field pilot would involve sensitivity analyses on the placement of initial
fill and subsequent fill in the vicinity of the groin field along with variations in groin length and spacing.
293,000 cy placement volume as the Oceanside fill in RSBP II.The prefill was distributed evenly from Tyson
Street at the northernmost groin to Forster Street just downdrift of the southernmost groin.Of the total prefill
amount,the 3,000-foot—long groin prefill area received 235,000 cy of prefill and the 750 feet of downdrift area
received 58,000 cy of prefill within the model.
4.2.2 Results and Analysis
Like the modeling ofthe full groin layout,the model predicts uniform retention of sediment throughout the groin
field.The initial fill volume was largely retained within the pilot groin system with accretion of sand in fillets
upcoast of each groin.The beach area retained remained relatively stable throughout the model simulation
with significant increases in beach width in each groin compartment relative to the initial shoreline.Downdrift
erosion was predicted to extend roughly a half mile south of the groin field indicating the importance of a
monitoring and management plan to mitigate these potential impacts.
The model results indicate the pilot configuration would retain a much larger beach area within the initial
placement zone in comparison to a Beach Nourishment only scenario (i.e.RBSP II).The beach width gained
from RBSP II in the original placement area was about 50 feet when averaged over the three-year period
following initial placement.The model results suggest 100-150 feet of beach width gains when averaged over
the model simulation.
While these results are promising,the model limitations must be acknowledged including the inability to
simulate the Oceanside Harbor structures and their influence on sediment supply to the study reach.The
groins are also simulated as impervious structures which may result in more retention than would occur in
reality if these structures are comprised of larger diameter armor stone.These model limitations (infinite supply
of sand and impervious groins)likely result in an overestimate of the beach width retained within the pilot
system.Additional analysis of the groin field pilot would involve sensitivity analyses on the placement of initial
fill and subsequent fill in the vicinity of the groin field along with variations in groin length and spacing.
GHD |City of Oceanside Beach Sand Replenishment and Retention Device Projectl Page 18
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GHD | City of Oceanside Beach Sand Replenishment and Retention Device Project| Page 19
Figure 11 Groin Field Pilot: Shoreline Change and Position
4.3 Scenario 3: Artificial Reef Buildout
4.3.1 Modeling Approach
The basis for design and placement of the artificial reefs came from guidance from the Coastal Engineering
Manual (CEM) as well as the USACE study referenced in section 6.1. The USACE study tested offshore
breakwater placements off Oceanside beach and reported positive results with a series of detached offshore
breakwaters. Length, spacing and distance from shore were based on CEM guidance for detached offshore
breakwaters. From Tyson Street to Buena Vista Lagoon, six reefs with 600-foot-long crests, spaced at 1,200
feet alongshore and placed 1,000 feet offshore. They were designed to attain a salient in the lee of the
structures, to allow for sand bypassing in the longshore direction. While the formation of a tombolo may result
Modeled Shoreline Change:Groin Pilot500|
40“‘_F'ilutModeled Pilut Groin 1:201:
E —FilmModeled Pilot Groin 117014v300-g —PilotModeled Pilot Groin 142015
8 200 -n.EHE 100 -.(—6.ELI.0 .W
.100 .Reach E Rear‘h f“'2:t—Reach A
0.00 1.06 2.13 3.19 4.25 5'31CrossShoreDistance(Miles)
Legend
Modeled Groin PilotShoreline Position 14'2015
—Groin PilotCrest
W
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Figure 11 Groin Field Pilot:Shoreline Change and Position
4.3 Scenario 3:Artificial Reef Buildout
4.3.1 Modeling Approach
The basis for design and placement of the artificial reefs came from guidance from the Coastal Engineering
Manual (CEM)as well as the USACE study referenced in section 6.1.The USACE study tested offshore
breakwater placements off Oceanside beach and reported positive results with a series of detached offshore
breakwaters.Length,spacing and distance from shore were based on CEM guidance for detached offshore
breakwaters.From Tyson Street to Buena Vista Lagoon,six reefs with 600-foot—long crests,spaced at 1,200
feet alongshore and placed 1,000 feet offshore.They were designed to attain a salient in the lee of the
structures,to allow for sand bypassing in the longshore direction.While the formation of a tombolo may result
GHD |City of Oceanside Beach Sand Replenishment and Retention Device Projectl Page 19
Jan. 4, 2022 Item 4 Page 157 of 229
GHD | City of Oceanside Beach Sand Replenishment and Retention Device Project| Page 20
in larger increases of beach width immediately behind the structure, it would impede the flow of entrained
sediment downdrift of the structures. The artificial reefs proposed are functionally the same as detached
breakwaters, but with design elements to enhance the likelihood of surfable waves breaking off the structure.
LITPACK only has the capability to model offshore breakwaters, so the artificial reefs were modeled as such.
This was found to be acceptable as the hydrodynamics are similar enough for the purposes of assessing
shoreline response.
The prefills used within the LITPACK model were the same amount and placement as the full groin layout
described in section 6.1.1. Both the North Carlsbad and Oceanside RBSP II fill amounts were used as a
downdrift prefill and project area prefill; respectively. This was done to provide a basis of comparison between
the two model runs.
Figure 12 Artificial Reef Full Layout Position
4.3.2 Results and Analysis
The model showed the formation of salient in the lee of each of the artificial breakwaters, with erosional effects
between the structures as expected. The model simulation indicated a fairly uniform salient behind each reef
structure with maximum predicted beach widths of 100-150 feet. Similar to the groin simulation, results in the
final year suggest significant accretion occurs at each structure, especially updrift of the northernmost reef.
The results illustrated in the final year are likely due to model limitations and may not reflect a realistic outcome.
The final simulation year (2015-2016) had a more energetic wave climate which increased the modeled
sediment transport rates. Since the model does not simulate the Oceanside Harbor structures and their effect
on littoral sediment supply, the amount of accretion predicted in this final year is likely overestimated. The
in larger increases of beach width immediately behind the structure,it would impede the flow of entrained
sediment downdrift of the structures.The artificial reefs proposed are functionally the same as detached
breakwaters,but with design elements to enhance the likelihood of surfable waves breaking off the structure.
LITPACK only has the capability to model offshore breakwaters,so the artificial reefs were modeled as such.
This was found to be acceptable as the hydrodynamics are similar enough for the purposes of assessing
shoreline response.
The prefills used within the LITPACK model were the same amount and placement as the full groin layout
described in section 6.1.1.Both the North Carlsbad and Oceanside RBSP ll fill amounts were used as a
downdrift prefill and project area prefill;respectively.This was done to provide a basis of comparison between
the two model runs.
Laud
WI may Layout
—Bleakwaer Crest
Figure 12 Artificial Reef Full Layout Position
4.3.2 Results and Analysis
The model showed the formation of salient in the lee of each of the artificial breakwaters,with erosional effects
between the structures as expected.The model simulation indicated a fairly uniform salient behind each reef
structure with maximum predicted beach widths of 100-150 feet.Similar to the groin simulation,results in the
final year suggest significant accretion occurs at each structure,especially updrift of the northernmost reef.
The results illustrated in the final year are likely due to model limitations and may not reflect a realistic outcome.
The final simulation year (2015-2016)had a more energetic wave climate which increased the modeled
sediment transport rates.Since the model does not simulate the Oceanside Harbor structures and their effect
on littoral sediment supply,the amount of accretion predicted in this final year is likely overestimated.The
GHD |City of Oceanside Beach Sand Replenishment and Retention Device Projectl Page 20
Jan. 4, 2022 Item 4 Page 158 of 229
GHD | City of Oceanside Beach Sand Replenishment and Retention Device Project| Page 21
updrift salient retained more sand than those of the downdrift, potentially blocking some of the bypassing of
the salient. Downdrift of the reef structures, the model predicted some erosion, but to a lesser extent than
predicted for the groin field. Similar to Groins, the volume of sand accumulated within the artificial reefs (based
on the 2015 model output), was 175% more than the NOS within the fill placement area.
Figure 13 Artificial Reefs: Shoreline Change and Position
4.4 Scenario 4: Artificial Reef Pilot
4.4.1 Modeling Approach
The artificial reef pilot project consisted of the northern two artificial reefs, spaced and sized the same as the
full layout. Two reefs were modeled as opposed to one to show effects on the shoreline between the two reefs.
A downdrift/prefill of the same amount and placement as the groin pilot was included in the LITPACK model
updrift salient retained more sand than those of the downdrift,potentially blocking some of the bypassing of
the salient.Downdrift of the reef structures,the model predicted some erosion,but to a lesser extent than
predicted for the groin field.Similar to Groins,the volume of sand accumulated within the artificial reefs (based
on the 2015 model output),was 175%more than the NOS within the fill placement area.
Modeled Shoreline Change:Art.Reef Layout vs.NOS
5“”I
—Modeled Art.RearLam 112014
—Modeled An.ReefLayout 112015E‘400-
‘E —ModeledAn.ReefLayout3/2016 /
g —Nourishment Only Scenario3/2016 /
8n.200-EgEE"E 0
Reach E R1 Reach C Reach A
-200 .0.00 1.06 2.13 3.19 4.25 5.3GrossShoreDistance(Miles)
Legend
—Artificial Reef Crest
Modeled Art.Reef Shoreline Position 3/2016
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Figure 13 Artificial Reefs:Shoreline Change and Position
4.4 Scenario 4:Artificial Reef Pilot
4.4.1 Modeling Approach
The artificial reef pilot project consisted of the northern two artificial reefs,spaced and sized the same as the
full layout.Two reefs were modeled as opposed to one to show effects on the shoreline between the two reefs.
A downdrift/prefill of the same amount and placement as the groin pilot was included in the LlTPACK model
GHD |City of Oceanside Beach Sand Replenishment and Retention Device Projectl Page 21
Jan. 4, 2022 Item 4 Page 159 of 229
GHD | City of Oceanside Beach Sand Replenishment and Retention Device Project| Page 22
(i.e. 293,000 cy placed from Tyson Street to Forster St. at the beginning of the model simulation). Of the total
prefill amount, the 3,000-foot-long artificial reef prefill area received 235,000 cy of prefill and the 750 feet of
downdrift area received 58,000 cy of prefill within the model. The distribution of prefill and downdrift fill was
optimized to minimize downdrift impacts via sensitivity tests of placement extent.
Figure 14 Artificial Reef Pilot Position
4.4.2 Results and Analysis
The model predicted large salient formation in the lee of each reef structure, with retention benefits extending
upcoast well beyond the influence of the offshore structures. As a result, the beach in between the reefs also
experiences significant accretion. More downdrift erosion was predicted for the pilot configuration extending
about a half mile past the structures in Reach C (Figure 18).
These model results suggest the reef structures would retain a much larger beach within the original placement
area in comparison to a Beach Nourishment only scenario. The amount of beach area retained throughout the
model simulation was comparable to the Groin Field Pilot results, except the planform distribution of sand
(i.e.293,000 cy placed from Tyson Street to Forster St.at the beginning of the model simulation).Of the total
prefill amount,the 3,000-foot-long artificial reef prefill area received 235,000 cy of prefill and the 750 feet of
downdrift area received 58,000 cy of prefill within the model.The distribution of prefill and downdrift fill was
optimized to minimize downdrift impacts via sensitivity tests of placement extent.
WWII!
—Rnitclu
—Rnit5hpe
-——RnckTo-e
Antieipaladsmdimflespuae
Salient
unwary-nu:I—-_l nu“unmhmummu
Figure 14 Artificial Reef Pilot Position
4.4.2 Results and Analysis
The model predicted large salient formation in the lee of each reef structure,with retention benefits extending
upcoast well beyond the influence of the offshore structures.As a result,the beach in between the reefs also
experiences significant accretion.More downdrift erosion was predicted for the pilot configuration extending
about a half mile past the structures in Reach C (Figure 18).
These model results suggest the reef structures would retain a much larger beach within the original placement
area in comparison to a Beach Nourishment only scenario.The amount of beach area retained throughout the
model simulation was comparable to the Groin Field Pilot results,except the planform distribution of sand
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GHD | City of Oceanside Beach Sand Replenishment and Retention Device Project| Page 23
would be different. Although the model predicted beach widths are quite large, these are subject to similar
model limitations which may be contributing to an overestimate of the potential retention benefits.
Since these offshore reef structures have not been widely implemented in the Southern California region there
is limited real world observations of how this system would function. Additional analysis of the Artificial Reef
Pilot may involve two-dimensional modeling to simulate the complicated hydrodynamics that may result from
these structures. This would provide another tool for estimating their ability to retain a sandy beach and the
interaction between two or more artificial reef structures placed in series along the pilot study area.
Figure 15 Artificial Reef Pilot: Shoreline Change and Position
would be different.Although the model predicted beach widths are quite large,these are subject to similar
model limitations which may be contributing to an overestimate of the potential retention benefits.
Since these offshore reef structures have not been widely implemented in the Southern California region there
is limited real world observations of how this system would function.Additional analysis of the Artificial Reef
Pilot may involve two-dimensional modeling to simulate the complicated hydrodynamics that may result from
these structures.This would provide another tool for estimating their ability to retain a sandy beach and the
interaction between two or more artificial reef structures placed in series along the pilot study area.
Modeled Shoreline Change:Art.Reef Pilot
—Modeled PilotArt.Reef Layout19013
400-
—Modeled PilotArt Reef |awut137014
—Modeled PilotArt.Reef Layout ”2015
200'Final-InitialPosition(fl)0IW
Reach E Rea Raph C Reach AKeisha
2.13 3.19CrossShoreDistance(Miles)
Legend
—Pilot Artificial Reef Crest
ModeledArt.ReefShoreline Position 112015
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Figure 1 5 Artificial Reef Pilot:Shoreline Change and Position
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Jan. 4, 2022 Item 4 Page 161 of 229
GHD | City of Oceanside Beach Sand Replenishment and Retention Device Project| Page 24
5. References
1.Coastal Frontiers Corporation. 2019. Regional Beach Monitoring Program Annual Report. Retrieved from:
https://www.sandag.org/index.asp?projectid=298&fuseaction=projects.detail
2.Moffatt & Nichol Engineers. (1982). Experimental Sand Bypass System at Oceanside Harbor, California.
3.Moffatt & Nichol Engineers. (1990). Sediment Budget Report Oceanside Littoral Cell. Coast of California
Storm and Tidal Waves Study, CCSTWS 90-2.
4.Moffatt & Nichol Engineers. (2001). Regional Beach Sand retention Strategy. Retrieved from:
https://www.sandag.org/uploads/publicationid/publicationid_2036_20694.pdf
5.Moffatt & Nichol Engineers. (2016) San Diego County Shoreline Protection Feasibility Study, Final
Sampling Analysis Plan Results Report.
6.NOAA CO-OPS, 2020. https://tidesandcurrents.noaa.gov/met.html?id=9410230 . Date accessed:
07/30/2020.
7.Noble Consultants, Inc. 1983. Preliminary Engineering Report. Beach Protection Facilities: Oceanside,
California.
8.Patsch K. & Griggs, G. 2007. Development of Sand Budgets for California’s Major Littoral Cells.
Retrieved from: https://dbw.parks.ca.gov/pages/28702/files/Sand_Budgets_Major_Littoral_Cells.pdf
9. TekMarine, Inc. 1987. Oceanside Littoral Cell Preliminary Sediment Budget Report. Coast of California
Storm and Tidal Waves Study, CCSTWS 87-4.
10.USACE, 2020. Wave Information Studies. http://wis.usace.army.mil. Date accessed: 07/28/20.
5.References
1.Coastal Frontiers Corporation.2019.Regional Beach Monitoring Program Annual Report.Retrieved from:
https://www.sandag.org/index.asp?projectid=298&fuseaction=projects.detail
2.Moffatt &Nichol Engineers.(1982).Experimental Sand Bypass System at Oceanside Harbor,California.
3.Moffatt &Nichol Engineers.(1990).Sediment Budget Report Oceanside Littoral Cell.Coast of California
Storm and Tidal Waves Study,CCSTWS 90-2.
4.Moffatt &Nichol Engineers.(2001).Regional Beach Sand retention Strategy.Retrieved from:
https://www.sandag.org/uploads/publicationid/publicationid_2036_20694.pdf
5.Moffatt &Nichol Engineers.(2016)San Diego County Shoreline Protection Feasibility Study,Final
Sampling Analysis Plan Results Report.
6.NOAA CO-OPS,2020.https://tidesandcurrents.noaa.gov/met.html?id=9410230 .Date accessed:
07/30/2020.
7.Noble Consultants,Inc.1983.Preliminary Engineering Report.Beach Protection Facilities:Oceanside,
California.
8.Patsch K.&Griggs,G.2007.Development of Sand Budgets for California’s Major Littoral Cells.
Retrieved from:https://dbw.parks.ca.gov/pages/28702/files/Sand_Budgets_Major_Littoral_CelIs.pdf
9.TekMarine,Inc.1987.Oceanside Littoral Cell Preliminary Sediment Budget Report.Coast of California
Storm and Tidal Waves Study,CCSTWS 87-4.
10.USACE,2020.Wave Information Studies.http://wis.usace.army.mil.Date accessed:07/28/20.
GHD |City of Oceanside Beach Sand Replenishment and Retention Device Projectl Page 24
Jan. 4, 2022 Item 4 Page 162 of 229
APPENDIX C
Detailed Multi-Criteria Analysis Results Table and Opinion of Probable Costs for Conceptual Alternatives
APPENDIX C
Detailed Multi-Criteria Analysis Results Table
and Opinion of Probable Costs for
Conceptual Alternatives
Jan. 4, 2022 Item 4 Page 163 of 229
OSIDE Assessment matrix
City Of Oceanside
Feasibility Analysis for Beach Sand Replenishment and Retention Device Project 1 2 3 4 5
Multi Criteria Analysis Weighted Scoring Matrix Low Average High
Score
(out of 5)
Weighted
Score
Score
(out of 5)
Weighted
Score
Score
(out of 5)
Weighted
Score
Score
(out of 5)
Weighted
Score
Score
(out of 5)
Weighted
Score
40%TECHNICAL PERFORMANCE
25%Creation/Restoration of Beach Overall performance of the system, pertaining to the long-term
creation/restoration of a beach. (1= poor performance/no beach
retained, 5 = Wide dry beach retained)
1 2%2 4%5 10%2 4%4 8%Reefs & groins provide most dry beach width added
within Oceanside. BN offers some temporary benefits
but longevity & width added (locally) are less reliable.
25%Down Drift Impacts Ability to mitigate adjacent shoreline changes. (1= down drift erosion, 5
= increased sediment to down drift systems)1 2%5 10%3 6%5 10%3 6%BN w/o structures improves down drift sediment supply.
SR alts also improve downdrift sediment supply by could
result in some localized down drift erosion which could
be mitigated through sediment management measures.
NP provides no reliable supply of coarse sand, so
downdrift erosion will continue.
25%Public Safety Ability to preserve safety of beach and ocean recreation through
improved lifeguard access. (1= exisiting conditions, 5 = Project
improves public safety)
1 2%3 6%3 6%3 6%3 6%Reefs provide stable beach width w/o lateral access
issues. Groins pose some challenges to lateral access
and would require additional lifeguard towers. Groins &
reefs introduce potential hazards/currents which pose
new risks for beach & ocean recreation. BN improves
beach width but only temporarily, leaving long stretches
of shoreline inaccessible. Pros & cons balance out
between alternatives. Public safety concerns could be
managed through design features and operational
measures (not a significant differentiator).
25%Sea Level Rise Adaptability Ability to be effective for up to 2ft of SLR. (1=not effective, 3=requires
some adaptive measures, 5=effective, easily accommodate 2ft of SLR)1 2%2 4%4 8%2 4%5 10%Reefs most effective in accomodating 2 ft SLR due to
wave energy dissipation alongshore. Groins & BN
provide some buffer to SLR due to incresed beach
widths. 100%8%24%30%24%30%
20%FINANCIAL
70%Life-cycle Costs Ensure the capital investment, O&M costs and adaptation costs
provides the best value for the amount. (1 = highest life-cycle cost, 5 =
lowest lifecycle cost)
5 14%5 14%4 11%4 11%1 3%Based on graduated scoring categories between highest
and lowest ranked alternatives.
30%In-direct economic benefits Indirect economic value provided by dry beach area available for
coastal access and recreation (1 = no economic benefit from increased
beach width, 5 = highest economic benefit from increased beach width)
1 1%2 2%5 6%2 2%4 5%Related to amount of sand retained within City of
Oceanside and increased opportunities for tourism &
beach visits
100%15%16%17%14%8%
40%ENVIRONMENTAL
20%Biological Resources Ability to preserve and/or enhance marine biological resources. (1=
negative, 5 = increased bio. Resources)1 2%3 5%4 6%3 5%5 8%SR alternatives provide a more stable intertidal beach
area. Groins and reefs occupy sandy sub-tidal habitat
but also provide some rocky substrate to support marine
bio habitat diversity.
20%Surfing Resources Ability to preserve or enhance exisiting surfing resources (1= Does not
preserve existing resources, 5 = Preserves and enhances surfing
resources).
1 2%3 5%4 6%3 5%4 6%Groins & reefs scored higher because of potential to
preserve and possibly enhance surfing resources.
Beach nourishment will help preserve surfing resources
but only temporarily and dependent on performance of
each nourishment. BN may also cause temporary surfing
impacts dependent on volume and grain size placed (i.e.
Imperial Beach in RBSP II).
20%Aesthetics Ability to preserve view corridors throughout Oceanside. (1= negative
aesthetic, 5 = positive aesthetics)2 3%3 5%4 6%3 5%4 6%Assuming aesthetics are linked to dry beach area.
Stable sandy beach provides a better aesthetic than a
rock revetment.
20%Beach Recreation Ability to preserve and enhance recreational opportunities, partuicularly
at high-use areas such as the Pier and South Strand reaches. (1= no
project, 5 = increased rec. opportunities)
1 2%3 5%5 8%3 5%5 8%Groins & Reefs score highest due to increased area
available for beach recreation (i.e. towel space) in most
accessible locations
20%Coastal Access Ability to enhance lateral beach access through the creation of stable
dry beach areas. (1= Existing conditions (no beach), 5 = improved
lateral access)
1 2%3 5%4 6%3 5%4 6%Groins & reefs provide stable beach for vertical access.
Lateral access features would need to be incorporated
into groins. BN only proviees both, but only temporarily
and dependent on the performance of each
nourishment. 100%10%24%34%24%35%
33%64%81%62%73%
Alternative 4
Comments
Multi-Purpose Artificial
Reef
SLRR Groin
Modifications
Alternative 3
TOTAL out of 100%
SUBTOTAL out of 40%
SUBTOTAL out of 20%
Alternative 1 Alternative 2
Importance No Project Beach Nourishment
Progam Groins
Scoring
Basis of EvaluationCriteria
SUBTOTAL out of 40%
\\ghdnet\ghd\US\San Diego\Projects\561\11213025\Tech\Report\Oceanside_Multi-Criteria_Analysis_rev3.xlsx OSIDE Assessment matrix 6/28/2021
R OSIDE Assessment matrix
City Of Oceanside
Feasibility Analysis for Beach Sand Replenishment and Retention Device Project Scoring 1 2 3 4 5
Multi Criteria Analysis Weighted Scoring Matrix Low Average High
Alternative 1 Alternative 2 Alternative 3 Alternative 4
.Beach Nourishment .SLRR Groin Multi-Purpose ArtificialNoPI'OJGCt GromsProgam Modifications Reef Comments
Weighted Weighted Weighted Weighted Weighted
Score Score Score Score Score
Importance Criteria Basis of Evaluation
40%TECHNICAL PERFORMANCE
25%Creation/Restoration of Beach Overall performance of the system,pertaining to the long-term 1 2%2 4%5 10%2 4%4 8%Reefs &groins provide most dry beach width added
creation/restoration of a beach.(1:poor performance/no beach within Oceanside.BN offers some temporary benefits
retained,5 =Wide dry beach retained)but longevity &width added (locally)are less reliable.
25%Down Drift Impacts Ability to mitigate adjacent shoreline changes.(1:down drift erosion,5 1 2%5 10%3 6%5 10%3 6%EN w/o structures improves down drift sediment supply.
=increased sediment to down drift systems)SR alts also improve downdrift sediment supply by could
result in some localized down drift erosion which could
be mitigated through sediment management measures.
NP provides no reliable supply of coarse sand,so
downdrift erosion will continue.
25%Public Safety Ability to preserve safety of beach and ocean recreation through 1 2%3 6%3 6%3 6%3 6%Reefs provide stable beach width w/o lateral access
improved lifeguard access.(1:exisiting conditions,5 =Project issues.Groins pose some challenges to lateral access
improves public safety)and would require additional lifeguard towers.Groins &
reefs introduce potential hazards/currents which pose
new risks for beach &ocean recreation.BN improves
beach width but only temporarily,leaving long stretches
of shoreline inaccessible.Pros &cons balance out
between alternatives.Public safety concerns could be
managed through design features and operational
measures (not a significant differentiator).
25%Sea Level Rise Adaptability Ability to be effective for up to 2ft of SLR.(1 =not effective,3=requires 1 2%2 4%4 8%2 4%5 10%Reefs most effective in accomodating 2 ft SLR due to
some adaptive measures,5=effective,easily accommodate 2ft of SLR)wave energy dissipation alongshore.Groins &BN
provide some buffer to SLR due to incresed beach
widths.100%SUBTOTAL out of 40%8%24%30%24%30%
70%Life-cycle Costs Ensure the capital investment,0&M costs and adaptation costs 5 14%5 14%4 1 1%4 1 1%1 3%Based on graduated scoring categories between highest
provides the best value for the amount.(1 =highest life-cycle cost,5 =and lowest ranked alternatives.
lowest lifecycle cost)
30%ln-direct economic benefits Indirect economic value provided by dry beach area available for 1 1%2 2%5 6%2 2%4 5%Related to amount of sand retained within City of
coastal access and recreation (1 =no economic benefit from increased Oceanside and increased opportunities for tourism &
beach width,5 =highest economic benefit from increased beach width)beach visits
100%SUBTOTAL out of 20%15%16%17%14%8%
20%Biological Resources Ability to preserve and/or enhance marine biological resources.(1:1 2%3 5%4 6%3 5%5 8%SR alternatives provide a more stable intertidal beach
negative,5 =increased bio.Resources)area.Groins and reefs occupy sandy sub-tidal habitat
but also provide some rocky substrate to support marine
bio habitat diversity.
20%Surfing Resources Ability to preserve or enhance exisiting surfing resources (1:Does not 1 2%3 5%4 6%3 5%4 6%Groins &reefs scored higher because of potential to
preserve existing resources,5 =Preserves and enhances surfing preserve and possibly enhance surfing resources.
resources).Beach nourishment will help preserve surfing resources
but only temporarily and dependent on performance of
each nourishment.BN may also cause temporary surfing
impacts dependent on volume and grain size placed (i.e.
Imperial Beach in RBSP ll).
20%Aesthetics Ability to preserve view corridors throughout Oceanside.(1:negative 2 3%3 5%4 6%3 5%4 6%Assuming aesthetics are linked to dry beach area.
aesthetic,5 =positive aesthetics)Stable sandy beach provides a better aesthetic than a
rock revetment.
20%Beach Recreation Ability to preserve and enhance recreational opportunities,partuicularly 1 2%3 5%5 8%3 5%5 8%Groins &Reefs score highest due to increased area
at high-use areas such as the Pier and South Strand reaches.(1:no available for beach recreation (i.e.towel space)in most
project,5 =increased rec.opportunities)accessible locations
Coastal Access Ability to enhance lateral beach access through the creation of stable 1 2%3 5%4 6%3 5%4 6%Groins &reefs provide stable beach for vertical access.
dry beach areas.(1:Existing conditions (no beach),5 =improved Lateral access features would need to be incorporated
lateral access)into groins.BN only proviees both,but only temporarily
and dependent on the performance of each
nourishment.SUBTOTAL out of 40%10%24%34%24%35%
TOTAL out of 100%33%64%81%62%73%
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Jan. 4, 2022 Item 4 Page 164 of 229
City of OceansideSand Retention Feasibility StudyOpinion of Probable Cost for AlternativesSummary of Alternatives Opinion of Project CostsDate:6/25/2021Alternative Item DescriptionPhase 1 (Initial ‐ 2030) Phase 2 (2030 ‐ 2035) Phase 3 (2035 ‐ 2040) TotalInitial Cost 1,000,000$ ‐$ ‐$ 1,000,000$ Beach Maintenance‐$ 1,000,000$ 1,000,000$ 2,000,000$ Adaptation‐$ ‐$ ‐$ ‐$ Total1,000,000$ 1,000,000$ 1,000,000$ 3,000,000$ Initial Cost10,000,000$ ‐$ ‐$ 10,000,000$ Beach Maintenance‐$ 9,000,000$ 9,000,000$ 18,000,000$ Adaptation‐$ ‐$ ‐$ ‐$ Total10,000,000$ 9,000,000$ 9,000,000$ 28,000,000$ Initial Cost32,000,000$ ‐$ ‐$ 32,000,000$ Beach Maintenance‐$ 7,000,000$ 7,000,000$ 14,000,000$ Adaptation‐$ ‐$ 5,000,000$ 5,000,000$ Total32,000,000$ 7,000,000$ 12,000,000$ 51,000,000$ Initial Cost16,000,000$ ‐$ ‐$ 16,000,000$ Beach Maintenance‐$ 9,000,000$ 9,000,000$ 18,000,000$ Adaptation‐$ ‐$ 2,000,000$ 2,000,000$ Total16,000,000$ 9,000,000$ 11,000,000$ 36,000,000$ Initial Cost95,000,000$ ‐$ ‐$ 95,000,000$ Beach Maintenance‐$ 7,000,000$ 7,000,000$ 14,000,000$ Adaptation‐$ ‐$ 39,000,000$ 39,000,000$ Total95,000,000$ 7,000,000$ 46,000,000$ 148,000,000$ No Project1 Beach Nourishment2 Groins4 Multi‐purpose Reefs3 SLRR Groin Mods\\ghdnet\ghd\US\San Diego\Projects\561\11213025\Tech\Report\Quantity Calcs\OSide_BN‐SR_Alternatives_OPCC_V2.xlsxCityofOceansideSandRetentionFeasibilityStudyOpinionofProbableCostforAlternativesSummaryofAlternativesOpinionofProjectCostsDate:6/25/2021Phase1(Initial-AlternativeItemDescription2030)Phase2(2030-2035)Phase3(2035-2040)InitialCost$1,000,000$-$-$1,000,000.BeachMaintenanceS-S1,000,000S1,000,000S2,000,000NoProiect,AdaptationS-S-S-5'TotalS1,000,000S1,000,000S1,000,000S3,000,000InitialCostS10,000,000S-S-510,000,000_BeachMaintenanceS—S9,000,000S9,000,000S18,000,0001BeachNourishment_AdaptationS-5-5'5'TotalS10,000,000S9,000,000S9,000,000S28,000,000initialCost532,000,000S-S-532,000,000_BeachMaintenanceS—S7,000,000S7,000,000S14,000,0002Groms_AdaptationS—S—S5,000,000S5,000,000TotalS32,000,000S7,000,000S12,000,000S51,000,000InitialCost516,000,000S-S-516,000,000_BeachMaintenanceS-S9,000,000S9,000,000S18,000,0003SLRRGromMods_AdaptationS—S—S2,000,000S2,000,000TotalS16,000,000S9,000,000S11,000,000S36,000,000InitialCostS95,000,000S-S-595,000,0004Multi—purposeBeachMaintenanceS—S7,000,000S7,000,000S14,000,000ReefsAdaptationS—S—S39,000,000S39,000,000TotalS95,000,000S7,000,000S46,000,000S148,000,000\\ghdnet\ghd\US\SanDiego\Projects\561\11213025\Tech\Report\QuantityCa|cs\OSide_BN—SR_A|ternatives_0PCC_V2.x|sxJan. 4, 2022Item 4 Page 165 of 229
City of Oceanside
Sand Retention Feasibility Study
Opinion of Probable Cost for Alternatives
Opinion of Costs for No Project
Date:6/25/2021
Phase 1 (Initial - 2030)Phase 2 (2030 - 2035)Phase 3 (2035 - 2040)
Item Item Description Qty Unit Rate Amount Qty Unit Rate Amount Qty Unit Rate Amount
Project Construction Costs
1 Mobilization (see note 1)1 LS -$ -$ -$ -$
2 Traffic Control 1 LS -$ -$ -$ -$
3 Beach nourishment 40,000 CY 15$ 600,000$ -$ -$
4 Maint. beach nourishment mobilization - LS 2,500,000$ -$ 0 LS 2,500,000$ -$ 0 LS 2,500,000$ -$
5 Maint. beach nourishment - CY 15$ -$ 40,000 CY 15$ 600,000$ 40,000 CY 15$ 600,000$
6 Adaptation
Project Construction Costs Total 600,000$ 600,000$ 600,000$
Project Professional Services Items
1 Geotechnical Investigations 0 LS 50,000$ -$ 0 LS 25,000$ -$ 0 LS 25,000$ -$
2 Survey 0 LS 25,000$ -$ 0 LS 20,000$ -$ 0 LS 20,000$ -$
3 Design 0%%600,000$ -$ 0%%600,000$ -$ 0%%600,000$ -$
4 Permits 0%%600,000$ -$ 0%%600,000$ -$ 0%%600,000$ -$
5 Construction Management 0%%600,000$ -$ 0%%600,000$ -$ 0%%600,000$ -$
Professional Services Total -$ -$ -$
Contingency 30%%600,000$ 180,000$ 30%%600,000$ 180,000$ 30%%600,000$ 180,000$
Project Total 780,000$ 780,000$ 780,000$
Project Total Rounded 1,000,000$ 1,000,000$ 1,000,000$
Notes:
1 No Project assumes the City contributes $600k for additional harbor dredging once every five years. Work will be performed by USACE contractor so no mobilization cost is included.
2 Quantity and unit price of harbor dredging sand will vary. Assumption of $20/cy used to be consistent with other estimates.
City of Oceanside
Sand Retention Feasibility Study
Opinion of Probable Cost for Alternatives
Opinion of Costs for No Project H
Date:6/25/2021
Phase 1 (Initial -2030)Phase 2 (2030 -2035)Phase 3 (2035 -2040)
Item Description
Project Construction Costs
1 Mobilization (see note 1)1 LS S -S —S -S —
2 Traffic Control 1 LS S -S —S -S —
3 Beach nourishment 40,000 CY S 15 S 600,000 S -S —
4 Maint.beach nourishment mobilization -LS S 2,500,000 S —0 LS S 2,500,000 S -0 LS S 2,500,000 S —
5 Maint.beach nourishment -CY S 15 S —40,000 CY S 15 S 600,000 40,000 CY S 15 S 600,000
6 Adaptation
Project Construction Costs Total S 600,000 S 600,000 S 600,000
Project Professional Services Items
1 Geotechnical Investigations 0 LS S 50,000 S —0 LS S 25,000 S -0 LS S 25,000 S —
2 Survey 0 LS S 25,000 S —0 LS S 20,000 S -0 LS S 20,000 S —
3 Design 0%%S 600,000 S —0%%S 600,000 S -0%%S 600,000 S —
4 Permits 0%%S 600,000 S —0%%S 600,000 S -0%%S 600,000 S —
5 Construction Management 0%%S 600,000 S —0%%S 600,000 S -0%%S 600,000 S —
Professional Services Total $-$-S -
Contingency 30%%S 600,000 S 180,000 30%%S 600,000 S 180,000 30%%S 600,000 S 180,000
Project Total S 780,000 S 780,000 S 780,000
Project Total Rounded S 1,000,000 S 1,000,000 S 1,000,000
Notes:
1 No Project assumes the City contributes S600k for additional harbor dredging once every five years.Work will be performed by USACE contractor so no mobilization cost is included.
2 Quantity and unit price of harbor dredging sand will vary.Assumption of S20/cy used to be consistent with other estimates.
Jan. 4, 2022 Item 4 Page 166 of 229
City of Oceanside
Sand Retention Feasibility Study
Opinion of Probable Cost for Alternatives
Opinion of Costs for Alternative 1 - Beach Nourishment
Date:6/25/2021
Phase 1 (Initial - 2030)Phase 2 (2030 - 2035)Phase 3 (2035 - 2040)
Item Item Description Qty Unit Rate Amount Qty Unit Rate Amount Qty Unit Rate Amount
Project Construction Costs
1 Mobilization (see note 1)1 LS 2,500,000$ 2,500,000$ -$ -$
2 Traffic Control 1 LS 150,000$ 150,000$ -$ -$
3 Beach nourishment 300,000 CY 15$ 4,623,000$ -$ -$
4 Maint. beach nourishment mobilization - LS 2,500,000$ -$ 1 LS 2,500,000$ 2,500,000$ 1 LS 2,500,000$ 2,500,000$
5 Maint. beach nourishment - CY 15$ -$ 300,000 CY 15$ 4,623,000$ 300,000 CY 15$ 4,623,000$
6 Adaptation
Project Construction Costs Total 7,273,000$ 7,123,000$ 7,123,000$
Project Professional Services Items
1 Geotechnical Investigations 1 LS 50,000$ 50,000$ 1 LS 25,000$ 25,000$ 1 LS 25,000$ 25,000$
2 Survey 1 LS 25,000$ 25,000$ 1 LS 20,000$ 20,000$ 1 LS 20,000$ 20,000$
3 Design 5%%7,273,000$ 363,650$ 5%%7,123,000$ 356,150$ 5%%7,123,000$ 356,150$
4 Permits 8%%7,273,000$ 581,840$ 5%%7,123,000$ 356,150$ 5%%7,123,000$ 356,150$
5 Construction Management 5%%7,273,000$ 363,650$ 5%%7,123,000$ 356,150$ 5%%7,123,000$ 356,150$
Professional Services Total 1,384,140$ 1,113,450$ 1,113,450$
Contingency 15%%8,657,140$ 1,298,571$ 15%%8,236,450$ 1,235,468$ 15%%8,236,450$ 1,235,468$
Project Total 9,955,711$ 9,471,918$ 9,471,918$
Project Total Rounded 10,000,000$ 9,000,000$ 9,000,000$
Notes:
1
2
Beach Nourishment mobilization assumed to be lump sum amount of $2.5M but could vary depending on the type of marine equipment used
Beach nourishment assumes 300,000 cy initial plus 2 later individual 300,000 cy renourishment events
City of Oceanside
Sand Retention Feasibility Study
Opinion of Probable Cost for Alternatives
Opinion of Costs for Alternative 1 -Beach Nourishment H
Date:6/25/2021
Phase 1 (Initial -2030)Phase 2 (2030 -2035)Phase 3 (2035 -2040)
Item Description
Project Construction Costs
1 Mobilization (see note 1)1 LS S 2,500,000 S 2,500,000 S -S —
2 Traffic Control 1 LS S 150,000 S 150,000 S -S —
3 Beach nourishment 300,000 CY S 15 S 4,623,000 S -S —
4 Maint.beach nourishment mobilization -LS S 2,500,000 S —1 LS S 2,500,000 S 2,500,000 1 LS S 2,500,000 S 2,500,000
5 Maint.beach nourishment -CY S 15 S —300,000 CY S 15 S 4,623,000 300,000 CY S 15 S 4,623,000
6 Adaptation
Project Construction Costs Total S 7,273,000 S 7,123,000 S 7,123,000
Project Professional Services Items
1 Geotechnical Investigations 1 LS S 50,000 S 50,000 1 LS S 25,000 S 25,000 1 LS S 25,000 S 25,000
2 Survey 1 LS S 25,000 S 25,000 1 LS S 20,000 S 20,000 1 LS S 20,000 S 20,000
3 Design 5%%S 7,273,000 S 363,650 5%%$7,123,000 $356,150 5%%5 7,123,000 $356,150
4 Permits 8%%S 7,273,000 S 581,840 5%%$7,123,000 $356,150 5%%5 7,123,000 $356,150
5 Construction Management 5%%S 7,273,000 S 363,650 5%%$7,123,000 $356,150 5%%5 7,123,000 $356,150
Professional Services Total S 1,384,140 S 1,113,450 S 1,113,450
Contingency 15%%S 8,657,140 S 1,298,571 15%%S 8,236,450 S 1,235,468 15%%S 8,236,450 S 1,235,468
Project Total S 9,955,711 S 9,471,918 S 9,471,918
Project Total Rounded S 10,000,000 S 9,000,000 S 9,000,000
Notes:
1 Beach Nourishment mobilization assumed to be lump sum amount of $2.5M but could vary depending on the type of marine equipment used
2 Beach nourishment assumes 300,000 cy initial plus 2 later individual 300,000 cy renourishment events
Jan. 4, 2022 Item 4 Page 167 of 229
City of Oceanside
Sand Retention Feasibility Study
Opinion of Probable Cost for Alternatives
Opinion of Costs for Alternative 2 - Groins
Date:6/25/2021
Phase 1 (Initial - 2030)Phase 2 (2030 - 2035)Phase 3 (2035 - 2040)
Item Item Description Qty Unit Rate Amount Qty Unit Rate Amount Qty Unit Rate Amount
Project Construction Costs
1 Mobilization (% other items see note 1)5%%13,067,171$ 653,359$ -$ -$
2 Traffic Control 1 LS 150,000$ 150,000$ -$ -$
3 New rock groins 44,128 CY 293$ 12,917,171$ -$ -$
4 Beach nourishment mobilization 1 LS 2,500,000$ 2,500,000$ -$ -$
5 Beach nourishment 300,000 CY 15$ 4,623,000$ -$ -$
6 Maint. beach nourishment mobilization - LS 2,500,000$ -$ 1 LS 2,500,000$ 2,500,000$ 1 LS 2,500,000$ 2,500,000$
7 Maint. beach nourishment - CY 15$ -$ 150,000 CY 15$ 2,311,500$ 150,000 CY 15$ 2,311,500$
8 Adaptation (see note 3)1 LS 3,200,000$ 3,200,000$
Project Construction Costs Total 20,843,529$ 4,811,500$ 8,011,500$
Project Professional Services Items
1 Geotechnical Investigations 1 LS 50,000$ 50,000$ 1 LS 25,000$ 25,000$ 1 LS 25,000$ 25,000$
2 Survey 1 LS 25,000$ 25,000$ 1 LS 20,000$ 20,000$ 1 LS 20,000$ 20,000$
3 Design 5%%20,843,529$ 1,042,176$ 5%%4,811,500$ 240,575$ 5%%8,011,500$ 400,575$
4 Permits 8%%20,843,529$ 1,667,482$ 5%%4,811,500$ 240,575$ 5%%8,011,500$ 400,575$
5 Construction Management 5%%20,843,529$ 1,042,176$ 5%%4,811,500$ 240,575$ 5%%8,011,500$ 400,575$
Professional Services Total 3,826,835$ 766,725$ 1,246,725$
Contingency 30%%24,670,364$ 7,401,109$ 30%%5,578,225$ 1,673,468$ 30%%9,258,225$ 2,777,468$
Project Total 32,071,474$ 7,251,693$ 12,035,693$
Project Total Rounded 32,000,000$ 7,000,000$ 12,000,000$
Notes:
1
2
3
Mobilization is 5% of all items except Beach Nourishment. Beach Nourishment mobilization assumed to be lump sum amount of $2.5M but could vary depending on the type of marine equipment used
Beach nourishment assumes 300,000 cy initial plus 2 later individual 150,000 cy renourishment events
Adaptation of groin structures assumes 25% of the initial line item cost for modifications at end of pilot phase.
City of Oceanside
Sand Retention Feasibility Study
Opinion of Probable Cost for Alternatives
Opinion of Costs for Alternative 2 -Groins
Date:6/25/2021
Phase 1 (Initial -2030)Phase 2 (2030 -2035)Phase 3 (2035 -2040)
Item Description
Project Construction Costs
1 Mobilization (%other items see note 1)5%%S 13,067,171 S 653,359 S —S -
2 Traffic Control 1 LS S 150,000 S 150,000 S —S -
3 New rock groins 44,128 CY S 293 S 12,917,171 S —S -
4 Beach nourishment mobilization 1 LS S 2,500,000 S 2,500,000 S —S -
5 Beach nourishment 300,000 CY S 15 S 4,623,000 S —S -
6 Maint.beach nourishment mobilization —LS S 2,500,000 S —1 LS S 2,500,000 S 2,500,000 1 LS S 2,500,000 S 2,500,000
7 Maint.beach nourishment —CY S 15 S —150,000 CY S 15 S 2,311,500 150,000 CY S 15 S 2,311,500
8 Adaptation (see note 3)1 LS S 3,200,000 S 3,200,000
Project Construction Costs Total S 20,843,529 S 4,811,500 S 8,011,500
Project Professional Services Items
1 Geotechnical Investigations 1 LS S 50,000 S 50,000 1 LS S 25,000 S 25,000 1 LS S 25,000 S 25,000
2 Survey 1 LS S 25,000 S 25,000 1 LS S 20,000 S 20,000 1 LS S 20,000 S 20,000
3 Design 5%%S 20,843,529 $1,042,176 5%%$4,811,500 5 240,575 5%%S 8,011,500 S 400,575
4 Permits 8%%$20,843,529 $1,667,482 5%%$4,811,500 5 240,575 5%%S 8,011,500 S 400,5755ConstructionManagement5%%$20,843,529 $1,042,176 5%%$4,811,500 5 240,575 5%%S 8,011,500 S 400,575
Professional Services Total S 3,826,835 S 766,725 S 1,246,725
Contingency 30%%S 24,670,364 S 7,401,109 30%%S 5,578,225 S 1,673,468 30%%S 9,258,225 S 2,777,468
Project Total S 32,071,474 S 7,251,693 S 12,035,693
Project Total Rounded S 32,000,000 S 7,000,000 S 12,000,000
Notes:
1 Mobilization is 5%of all items except Beach Nourishment.Beach Nourishment mobilization assumed to be lump sum amount of $2.5M but could vary depending on the type of marine equipment used
2 Beach nourishment assumes 300,000 cy initial plus 2 later individual 150,000 cy renourishment events
3 Adaptation of groin structures assumes 25%of the initial line item cost for modifications at end of pilot phase.
Jan. 4, 2022 Item 4 Page 168 of 229
City of Oceanside
Sand Retention Feasibility Study
Opinion of Probable Cost for Alternatives
Opinion of Costs for Alternative 3 - SLRR Groin Mods
Date:6/25/2021
Phase 1 (Initial - 2030)Phase 2 (2030 - 2035)Phase 3 (2035 - 2040)
Item Item Description Qty Unit Rate Amount Qty Unit Rate Amount Qty Unit Rate Amount
Project Construction Costs
1 Mobilization (% other items see note 2)5%%2,784,485$ 139,224$ -$ -$
2 Traffic Control 1 LS 150,000$ 150,000$ -$ -$
3 Beach nourishment mobilization 1 LS 2,500,000$ 2,500,000$ -$ -$
4 Beach nourishment 300,000 CY 15$ 4,623,000$ -$ -$
5 SLR Groin mods (300' ext.)9,000 CY 293$ 2,634,485$ -$ -$
6 Maint. beach nourishment mobilization - LS 2,500,000$ -$ 1 LS 2,500,000$ 2,500,000$ 1 LS 2,500,000$ 2,500,000$
7 Maint. beach nourishment - CY 15$ -$ 300,000 CY 15$ 4,623,000$ 300,000 CY 15$ 4,623,000$
8 Adaptation (see note 3)1 LS 1,300,000$ 1,300,000$
Project Construction Costs Total 10,046,709$ 7,123,000$ 8,423,000$
Project Professional Services Items
1 Geotechnical Investigations 1 LS 50,000$ 50,000$ 1 LS 25,000$ 25,000$ 1 LS 25,000$ 25,000$
2 Survey 1 LS 25,000$ 25,000$ 1 LS 20,000$ 20,000$ 1 LS 20,000$ 20,000$
3 Design 5%%10,046,709$ 502,335$ 5%%7,123,000$ 356,150$ 5%%8,423,000$ 421,150$
4 Permits 8%%10,046,709$ 803,737$ 5%%7,123,000$ 356,150$ 5%%8,423,000$ 421,150$
5 Construction Management 5%%10,046,709$ 502,335$ 5%%7,123,000$ 356,150$ 5%%8,423,000$ 421,150$
Professional Services Total 1,883,408$ 1,113,450$ 1,308,450$
Contingency 30%%11,930,116$ 3,579,035$ 15%%8,236,450$ 1,235,468$ 15%%9,731,450$ 1,459,718$
Project Total 15,509,151$ 9,471,918$ 11,191,168$
Project Total Rounded 16,000,000$ 9,000,000$ 11,000,000$
Notes:
1
2
3
4
Assumes similar head section geometry of groin alternatives applied to end of existing SLR groin.
Mobilization is 5% of all items except Beach Nourishment. Beach Nourishment mobilization assumed to be lump sum amount of $2.5M but could vary depending on the type of marine equipment used
Beach nourishment assumes 300,000 cy initial plus 2 later individual 300,000 cy renourishment events
Adaptation of groin structure assumes 50% of the initial line item cost for modifications at end of pilot phase.
City of Oceanside
Sand Retention Feasibility Study
Opinion of Probable Cost for Alternatives
Opinion of Costs for Alternative 3 -SLRR Groin Mods
Date:6/25/2021
Phase 1 (Initial -2030)Phase 2 (2030 -2035)Phase 3 (2035 -2040)
Item Description
Project Construction Costs
1 Mobilization (%other items see note 2)5%%S 2,784,485 S 139,224 S -S -
2 Traffic Control 1 LS S 150,000 S 150,000 S -S -
3 Beach nourishment mobilization 1 LS S 2,500,000 S 2,500,000 S -S -
4 Beach nourishment 300,000 CY S 15 S 4,623,000 S -S -
5 SLR Groin mods (300'ext.)9,000 CY S 293 S 2,634,485 S -S -
6 Maint.beach nourishment mobilization —LS S 2,500,000 S -1 LS S 2,500,000 S 2,500,000 1 LS S 2,500,000 S 2,500,000
7 Maint.beach nourishment —CY S 15 S -300,000 CY S 15 S 4,623,000 300,000 CY S 15 S 4,623,000
8 Adaptation (see note 3)1 LS S 1,300,000 S 1,300,000
Project Construction Costs Total S 10,046,709 S 7,123,000 S 8,423,000
Project Professional Services Items
1 Geotechnical Investigations 1 LS S 50,000 S 50,000 1 LS S 25,000 S 25,000 1 LS S 25,000 S 25,000
2 Survey 1 LS S 25,000 S 25,000 1 LS S 20,000 S 20,000 1 LS S 20,000 S 20,000
3 Design 5%%S 10,046,709 $502,335 5%%S 7,123,000 S 356,150 5%%S 8,423,000 $421,150
4 Permits 8%%$10,046,709 $803,737 5%%S 7,123,000 S 356,150 5%%S 8,423,000 S 421,1505ConstructionManagement5%%$10,046,709 $502,335 5%%S 7,123,000 S 356,150 5%%S 8,423,000 S 421,150
Professional Services Total S 1,883,408 S 1,113,450 S 1,308,450
Contingency 30%%S 11,930,116 S 3,579,035 15%%S 8,236,450 S 1,235,468 15%%S 9,731,450 S 1,459,718
Project Total S 15,509,151 S 9,471,918 S 11,191,168
Project Total Rounded S 16,000,000 S 9,000,000 S 11,000,000
Notes:
1 Assumes similar head section geometry of groin alternatives applied to end of existing SLR groin.
2 Mobilization is 5%of all items except Beach Nourishment.Beach Nourishment mobilization assumed to be lump sum amount of $2.5M but could vary depending on the type of marine equipment used
3 Beach nourishment assumes 300,000 cy initial plus 2 later individual 300,000 cy renourishment events
4 Adaptation of groin structure assumes 50%of the initial line item cost for modifications at end of pilot phase.
Jan. 4, 2022 Item 4 Page 169 of 229
City of Oceanside
Sand Retention Feasibility Study
Opinion of Probable Cost for Alternatives
Opinion of Costs for Alternative 4 - MP Reefs
Date:6/25/2021
Phase 1 (Initial - 2030)Phase 2 (2030 - 2035)Phase 3 (2035 - 2040)
Item Item Description Qty Unit Rate Amount Qty Unit Rate Amount Qty Unit Rate Amount
Project Construction Costs
1 Mobilization (% other items see note 1)5%%51,939,013$ 2,596,951$ -$ -$
2 Traffic Control 1 LS 150,000$ 150,000$ -$ -$
3 MP Reefs armor stone 230,000 CY 225$ 51,789,013$ -$ -$
4 Beach nourishment mobilization 1 LS 2,500,000$ 2,500,000$ -$ -$
5 Beach nourishment 300,000 CY 15$ 4,623,000$ -$ -$
6 Maint. beach nourishment mobilization - LS 2,500,000$ -$ 1 LS 2,500,000$ 2,500,000$ 1 LS 2,500,000$ 2,500,000$
7 Maint. beach nourishment - CY 15$ -$ 150,000 CY 15$ 2,311,500$ 150,000 CY 15$ 2,311,500$
8 Adaptation (see note 3)1 LS 25,900,000$ 25,900,000$
Project Construction Costs Total 61,658,964$ 4,811,500$ 30,711,500$
Project Professional Services Items
1 Geotechnical Investigations 1 LS 50,000$ 50,000$ 1 LS 25,000$ 25,000$ 1 LS 25,000$ 25,000$
2 Survey 1 LS 25,000$ 25,000$ 1 LS 20,000$ 20,000$ 1 LS 20,000$ 20,000$
3 Design 5%%61,658,964$ 3,082,948$ 5%%4,811,500$ 240,575$ 5%%30,711,500$ 1,535,575$
4 Permits 8%%61,658,964$ 4,932,717$ 5%%4,811,500$ 240,575$ 5%%30,711,500$ 1,535,575$
5 Construction Management 5%%61,658,964$ 3,082,948$ 5%%4,811,500$ 240,575$ 5%%30,711,500$ 1,535,575$
Professional Services Total 11,173,613$ 766,725$ 4,651,725$
Contingency 30%%72,832,577$ 21,849,773$ 30%%5,578,225$ 1,673,468$ 30%%35,363,225$ 10,608,968$
Project Total 94,682,350$ 7,251,693$ 45,972,193$
Project Total Rounded 95,000,000$ 7,000,000$ 46,000,000$
Notes:
1
2
3
Mobilization is 5% of all items except Beach Nourishment. Beach Nourishment mobilization assumed to be lump sum amount of $2.5M but could vary depending on the type of marine equipment used
Beach nourishment assumes 300,000 cy initial plus 2 later individual 150,000 cy renourishment events
Adaptation of reef structures assumes 50% of the initial line item cost for modifications at end of pilot phase.
City of Oceanside
Sand Retention Feasibility Study
Opinion of Probable Cost for Alternatives
Opinion of Costs for Alternative 4 -MP Reefs
Date:6/25/2021
H
H
Phase 1 (Initial -2030)Phase 2 (2030 -2035)Phase 3 (2035 -2040)
Item Description Qty Unit Rate Amount Qty Unit Rate Amount Amount
Project Construction Costs
1 Mobilization (%other items see note 1)5%%S 51,939,013 S 2,596,951 S -S —
2 Traffic Control 1 LS S 150,000 S 150,000 S -S —
3 MP Reefs armor stone 230,000 CY S 225 S 51,789,013 S -S —
4 Beach nourishment mobilization 1 LS S 2,500,000 S 2,500,000 S -S —
5 Beach nourishment 300,000 CY S 15 S 4,623,000 S -S —
6 Maint.beach nourishment mobilization -LS S 2,500,000 S -1 LS S 2,500,000 S 2,500,000 1 LS S 2,500,000 S 2,500,000
7 Maint.beach nourishment -CY S 15 S -150,000 CY s 15 $2,311,500 150,000 CY s 15 5 2,311,500
8 Adaptation (see note 3)1 LS S 25,900,000 S 25,900,000
Project Construction Costs Total S 61,658,964 S 4,811,500 S 30,711,500
Project Professional Services Items
1 Geotechnical Investigations 1 LS S 50,000 S 50,000 1 LS S 25,000 S 25,000 1 LS S 25,000 S 25,000
2 Survey 1 LS S 25,000 S 25,000 1 LS S 20,000 S 20,000 1 LS S 20,000 S 20,000
3 Design 5%%S 61,658,964 5 3,082,948 5%%S 4,811,500 $240,575 5%%$30,711,500 $1,535,575
4 Permits 8%%S 61,658,964 5 4,932,717 5%%$4,811,500 $240,575 5%%$30,711,500 $1,535,575
5 Construction Management 5%%S 61,658,964 5 3,082,948 5%%$4,811,500 $240,575 5%%$30,711,500 $1,535,575
Professional Services Total S 11,173,613 S 766,725 S 4,651,725
Contingency 30%%S 72,832,577 S 21,849,773 30%%S 5,578,225 S 1,673,468 30%%S 35,363,225 S 10,608,968
Project Total S 94,682,350 S 7,251,693 S 45,972,193
Project Total Rounded S 95,000,000 S 7,000,000 S 46,000,000
Notes:
1 Mobilization is 5%of all items except Beach Nourishment.Beach Nourishment mobilization assumed to be lump sum amount of $2.5M but could vary depending on the type of marine equipment used
2 Beach nourishment assumes 300,000 cy initial plus 2 later individual 150,000 cy renourishment events
3 Adaptation of reef structures assumes 50%of the initial line item cost for modifications at end of pilot phase.
Jan. 4, 2022 Item 4 Page 170 of 229
APPENDIX D
Scripps Institute of Oceanography Scientific Monitoring Plan
APPENDIX D
Scripps Institute of Oceanography Scientific
Monitoring Plan
Jan. 4, 2022 Item 4 Page 171 of 229
The Power of Commitment
11213025 1
March 08, 2021
Scientific Monitoring Plan – DRAFT Submitted by Dr. Adam Young, Laura Engeman, Scripps Institution of Oceanography
1.Introduction
Our understanding is that the City of Oceanside is considering various sand retention and sand replenishment
strategies to help combat the effects of chronic erosion of their shoreline. These strategies consist of artificial
reefs, groins and various mechanisms to redistribute or deliver sand to southern Oceanside beaches. The
City’s approach for this Project would be to pilot a recommended strategy to show proof of concept before
implementing the full strategy. The pilot project would be carefully monitored for physical, biological and social
performance for a period of time before moving forward. SIO was engaged by GHD to support the Project in
the development of a scientific baseline and monitoring strategy/framework for this Project. A scientific baseline
survey was conducted on January 14, 2021 of both the beach and nearshore profile.
The project area is assumed to extend from the Oceanside Pier to Buena Vista Lagoon where the beach
retention or nourishment strategies are expected to be deployed. Given this reach, our proposed monitoring
area would extend from the Oceanside Harbor to Agua Hedionda Lagoon.
2.Purpose
To develop a suite of scientifically robust monitoring strategies that would help inform the understanding of
beach processes and changing conditions in Oceanside. If implemented, the monitoring program would
evaluate beach response to a sand replenishment or sand retention pilot project and inform management
actions (e.g., structure modification or where to place sand).
The monitoring strategies leverage available data and resources to support the evaluation of the proposed
sand retention and nourishment strategies and are specifically focused on monitoring potential downdrift
impacts (i.e., how any neighboring beaches may be affected by these strategies). The proposed monitoring
plan does not address biological monitoring.
3.Proposed Sand Retention and Nourishment Project
Overview
3.1 Sand Retention Pilot Project:
The proposed sand retention pilot project would install 4 groins or two artificial reefs south of the Oceanside
Pier. (Figure 1).
March 08,2021
Scientific Monitoring Plan —DRAFT
Submitted by Dr.Adam Young,Laura Engeman,Scripps Institution of Oceanography
1.Introduction
Our understanding is that the City of Oceanside is considering various sand retention and sand replenishment
strategies to help combat the effects of chronic erosion of their shoreline.These strategies consist of artificial
reefs,groins and various mechanisms to redistribute or deliver sand to southern Oceanside beaches.The
City’s approach for this Project would be to pilot a recommended strategy to show proof of concept before
implementing the full strategy.The pilot project would be carefully monitored for physical,biological and social
performance for a period of time before moving fonrvard.SIO was engaged by GHD to support the Project in
the development of a scientific baseline and monitoring strategy/framework for this Project.A scientific baseline
survey was conducted on January 14,2021 of both the beach and nearshore profile.
The project area is assumed to extend from the Oceanside Pier to Buena Vista Lagoon where the beach
retention or nourishment strategies are expected to be deployed.Given this reach,our proposed monitoring
area would extend from the Oceanside Harbor to Agua Hedionda Lagoon.
2.Purpose
To develop a suite of scientifically robust monitoring strategies that would help inform the understanding of
beach processes and changing conditions in Oceanside.If implemented,the monitoring program would
evaluate beach response to a sand replenishment or sand retention pilot project and inform management
actions (e.g.,structure modification or where to place sand).
The monitoring strategies leverage available data and resources to support the evaluation of the proposed
sand retention and nourishment strategies and are specifically focused on monitoring potential downdrift
impacts (i.e.,how any neighboring beaches may be affected by these strategies).The proposed monitoring
plan does not address biological monitoring.
3.Proposed Sand Retention and Nourishment Project
Overview
3.1 Sand Retention Pilot Project:
The proposed sand retention pilot project would install 4 groins or two artificial reefs south of the Oceanside
Pier.(Figure 1).
—)The Power of Commitment
11213025 1Jan. 4, 2022 Item 4 Page 172 of 229
The Power of Commitment
11213025 2
Figure 1 Example configuration in Oceanside.
3.2 Sand Replenishment Sediment Management Option:
The proposed sand replenishment project would use a series of underground pipelines with a mobile bypass
system or other method to redistribute sand within the City. This option would source sand from areas where
sand is abundant and transport it to areas of need. The replenishment strategy would also seek to modify the
federal maintenance dredging program placement regime to either 1) place sand further south within the City or
to 2) place sand in the fall when the predominate longshore current is to the south. (Figures 2).
Figure 2 Potential sites for Oceanside sand sourcing
LegendPumGroinuyom-—-RockToeRuckCrest
Figure 1 Example configuration in Oceanside.
3.2 Sand Replenishment Sediment Management Option:
The proposed sand replenishment project would use a series of underground pipelines with a mobile bypass
system or other method to redistribute sand within the City.This option would source sand from areas where
sand is abundant and transport it to areas of need.The replenishment strategy would also seek to modify the
federal maintenance dredging program placement regime to either 1)place sand further south within the City or
to 2)place sand in the fall when the predominate longshore current is to the south.(Figures 2).
Figure 2 Potential sites for Oceanside sand sourcing
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11213025 2Jan. 4, 2022 Item 4 Page 173 of 229
The Power of Commitment
11213025 3
4.Proposed Sand Retention and Replenishment Pilot
Monitoring Plan
4.1 Sand Retention and Replenishment Monitoring Strategy
The proposed monitoring strategies seek to answer the following questions:
1.Pilot sand retention and/or replenishment pilot performance – has the pilot resulted in increased beach
widths and/or sand volume as compared to baseline?
2.Downdrift and sand sources impacts – has the sand retention pilot impacted adjacent or neighboring
beaches as compared to baseline conditions and has the sand replenishment pilot impacted beaches
were sand was sourced?
3.How has the sand retention and/or sand replenishment pilot responded to extreme oceanographic
conditions (waves, tides, sea levels, runup, overtopping) during the study period? (i.e. response to
extreme conditions compared with other nearby beach areas and pilot response to extreme conditions
over time as beach width/volume potentially expands)
4.How has the pilot impacted recreation (passive and active uses of the beach) and public safety?
Each monitoring approach is assigned a relative importance score (ranging low to high) to address the overall
task and objectives. Some monitoring approaches are complementary and/or redundant and the relative
importance score depends on what monitoring approaches are selected.
4.1.1 Routine Monitoring
(Relative importance = High) Topographic surveys should be pre and post construction, and then conducted
monthly or quarterly to capture annual maximum and minimum elevation conditions. Bathymetric surveys
should be conducted quarterly to monitor offshore sand elevations throughout the study area and around the
harbor mouth. These surveys might consist of a combination lidar, jet ski GPS based surveys, ARGUS, etc.
These surveys can be compared to historical survey data to determine regional sediment changes and
effectiveness of the project. Pre and post nourishment surveys could be timed with quarterly or monthly routine
surveys.
(Relative importance = Med-High) Community-conducted surveys: If topographic surveys are run only on a
quarterly basis, it is suggested that monthly community beach surveys be conducted to provide more frequent
assessments of sediment changes.
(Relative importance = low) Seasonal sand sampling (or photo-based grain size analysis) should be
conducted to monitor potential change is grain size distribution than can influence beach morphology, runup,
and surfing conditions.
Routine monitoring should continue for a minimum of 5 years to monitor the site in a range of wave conditions
and evaluate potential long-term impacts.
4.1.2 Extreme Event Monitoring
(Relative importance = med-high) Routine surveys should be supplemented by post storm event surveys to
capture beach storm response and response elevated wave and tide conditions. Backshore flooding and
damage should be documented with field observations.
Topographic surveys should be conducted post storm events. These surveys might consist of a combination
lidar, jet ski GPS based surveys, ARGUS, etc. These surveys can be compared to ongoing survey data to
determine regional sediment changes and effectiveness of the project. CDIP and SIO-MOP data would provide
information on tide/wave/wind conditions to evaluate relative storm intensity.
4.Proposed Sand Retention and Replenishment Pilot
Monitoring Plan
4.1 Sand Retention and Replenishment Monitoring Strategy
The proposed monitoring strategies seek to answer the following questions:
1.Pilot sand retention and/or replenishment pilot performance —has the pilot resulted in increased beach
widths and/or sand volume as compared to baseline?
2.Downdrift and sand sources impacts —has the sand retention pilot impacted adjacent or neighboring
beaches as compared to baseline conditions and has the sand replenishment pilot impacted beaches
were sand was sourced?
3.How has the sand retention and/or sand replenishment pilot responded to extreme oceanographic
conditions (waves,tides,sea levels,runup,overtopping)during the study period?(i.e.response to
extreme conditions compared with other nearby beach areas and pilot response to extreme conditions
over time as beach width/volume potentially expands)
4.How has the pilot impacted recreation (passive and active uses of the beach)and public safety?
Each monitoring approach is assigned a relative importance score (ranging low to high)to address the overall
task and objectives.Some monitoring approaches are complementary and/or redundant and the relative
importance score depends on what monitoring approaches are selected.
4.1.1 Routine Monitoring
(Relative importance =High)Topographic surveys should be pre and post construction,and then conducted
monthly or quarterly to capture annual maximum and minimum elevation conditions.Bathymetric surveys
should be conducted quarterly to monitor offshore sand elevations throughout the study area and around the
harbor mouth.These surveys might consist of a combination lidar,jet ski GPS based surveys,ARGUS,etc.
These surveys can be compared to historical survey data to determine regional sediment changes and
effectiveness of the project.Pre and post nourishment surveys could be timed with quarterly or monthly routine
surveys.
(Relative importance =Med-High)Community-conducted surveys:If topographic surveys are run only on a
quarterly basis,it is suggested that monthly community beach surveys be conducted to provide more frequent
assessments of sediment changes.
(Relative importance =low)Seasonal sand sampling (or photo-based grain size analysis)should be
conducted to monitor potential change is grain size distribution than can influence beach morphology,runup,
and surfing conditions.
Routine monitoring should continue for a minimum of 5 years to monitor the site in a range of wave conditions
and evaluate potential long-term impacts.
4.1.2 Extreme Event Monitoring
(Relative importance =med-high)Routine surveys should be supplemented by post storm event surveys to
capture beach storm response and response elevated wave and tide conditions.Backshore flooding and
damage should be documented with field observations.
Topographic surveys should be conducted post storm events.These surveys might consist of a combination
lidar,jet ski GPS based surveys,ARGUS,etc.These surveys can be compared to ongoing survey data to
determine regional sediment changes and effectiveness of the project.CDIP and SlO-MOP data would provide
information on tide/wave/wind conditions to evaluate relative storm intensity.
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11213025 3Jan. 4, 2022 Item 4 Page 174 of 229
The Power of Commitment
11213025 4
(Relative importance = Med-High) Community-conducted surveys: If topographic surveys are not possible, it
is suggested that community beach surveys be conducted to provide an assessment of post-storm sediment
conditions. Community surveys, lifeguard reports, and surfline cameras could also be used to document post
storm field conditions.
4.1.3 Downdrift and Sand Source Impacts
(Relative importance = High) Detailed analysis and monitoring should be conducted downdrift of project
locations to evaluate impacts to neighboring beaches. Downdrift impacts are particularly important for any sand
retention strategies. For the proposed sand replenishment pilots, detailed analysis and monitoring should also
be conducted at sand removal locations to evaluate impacts.
4.1.4 Oceanographic Analysis
(Relative importance = Med) Potential changes to nearshore wave energy and currents that could impact
sediment dynamics and recreation activities should be monitored. Monitoring could consist of a combination or
offshore and in situ sensors, video monitoring (Argus video), etc.
4.1.5 Recreational Impact
(Relative importance = High) Impacts to recreation such as swimming, surfing, boating, and beach activities
should be documented quantitatively if possible. For example, methods to count the number of people in video
images could be developed for a quantitative metric of beach use. Monitoring should include safety issues such
as rip currents and dangers associated with any new hard structures. Monitoring techniques could include a
combination of field documentation, video monitoring, etc.
Table 1 Monitoring strategies and metrics
Name Monitoring question this helps inform?
Monitoring Goal Metric/ Analysis Monitoring Approach Potential leveraged resources
Routine Monitoring 1,2,4 Compare and evaluate sediment accretion and retention following the implementation of the pilot sand retention strategy (“Baseline and As Built Conditions”) and pre/post sand replenishment conditions
Change in beach sand volume and beach width before and post sand retention structure construction and before and after sand
replenishments.
Changes in sand size distributions
Pre and post baseline surveys of beach topography
Monthly or quarterly topographic beach surveys and quarterly
bathymetry
Monthly community-conducted beach surveys
Sand Sampling
Argus video
SIO LiDAR seasonal surveys (2017-2021) of Oceanside if continued.
SIO quarterly LiDAR (subaerial topography) and jet-ski (nearshore bathymetry) surveys
could be expanded to include Oceanside
The piloted community-led monthly beach width monitoring with GPS if continued.
Historical and ongoing beach surveys (SANDAG’s regional shoreline monitoring program, historical airborne lidar, etc).
(Relative importance =Med-High)Community-conducted surveys:If topographic surveys are not possible,it
is suggested that community beach surveys be conducted to provide an assessment of post-storm sediment
conditions.Community surveys,lifeguard reports,and surfline cameras could also be used to document post
storm field conditions.
4.1.3 Downdrift and Sand Source Impacts
(Relative importance =High)Detailed analysis and monitoring should be conducted downdrift of project
locations to evaluate impacts to neighboring beaches.Downdrift impacts are particularly important for any sand
retention strategies.For the proposed sand replenishment pilots,detailed analysis and monitoring should also
be conducted at sand removal locations to evaluate impacts.
4.1.4 Oceanographic Analysis
(Relative importance =Med)Potential changes to nearshore wave energy and currents that could impact
sediment dynamics and recreation activities should be monitored.Monitoring could consist of a combination or
offshore and in situ sensors,video monitoring (Argus video),etc.
4.1.5 Recreational Impact
(Relative importance =High)Impacts to recreation such as swimming,surfing,boating,and beach activities
should be documented quantitatively if possible.For example,methods to count the number of people in video
images could be developed for a quantitative metric of beach use.Monitoring should include safety issues such
as rip currents and dangers associated with any new hard structures.Monitoring techniques could include a
combination of field documentation,video monitoring,etc.
Table 1 Monitoring strategies and metrics
Monitoring
question
Monitoring Goal Metric/Analysis Monitoring
Approach
Potential leveragedresources
this helps
inform?
the pilot sand
retention strategy sand beach surveys
and quarterly
Routine 1,2,4 Compare and Change in beach Pre and post SIO LiDAR seasonal
Monitoring evaluate sand volume and baseline surveys surveys (2017-2021)
sediment beach width of beach of Oceanside if
accretion and before and post topography continued.
retention sand retention Monthly or
following the structure .implementation of construction and 3::oréerralghic 8'0 quarterly L'DARbeforeandafter(subaerral topography)
and jet-ski (nearshore
bathymetry)surveys(3371882333n replenrshments.bathymetry could be expanded toandpre/post .Include OceansrdesandChangesInsandMonthlyreplenishmentsrzedrstrrbutronscommunity—The piloted
conditions conducted beach community-ledsurveysmonthlybeach width
Sand Sampling
Argus video
monitoring with GPS if
continued.
Historical and ongoing
beach surveys
(SANDAG’s regional
shoreline monitoring
program,historical
airborne Iidar,etc).
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11213025 4Jan. 4, 2022 Item 4 Page 175 of 229
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11213025 5
Name Monitoring question this helps inform?
Monitoring Goal Metric/ Analysis Monitoring Approach Potential leveraged resources
Extreme Event Monitoring 3 Evaluate beach and backshore response to large coastal events to determine performance of strategies and additional nourishment/ maintenance needs
Change in beach sand volume and/or beach width
Wave runup and overtopping
Comparative response to other north county beaches
Evidence of overtopping, flooding, and backshore damage
Post event topographic survey
Post event community- beach width surveys
Post storm field inspection to document (photos, etc.) overtopping, flooding, backshore erosion, and infrastructure damage
Argus Video
CDIP buoys
SIO-MOP Data
Surfline Cameras
Lifeguard
Logs/Reports
If continued, the piloted community-led program could be expanded to also conduct post-event monitoring of beach width.
Downdrift Impacts 2 Evaluate sediment downdrift impacts
Evaluate sand source impacts (if applicable)
Compare sediment accretion on adjacent beaches, offshore, sand source locations (if applicable), and around the harbor mouth
Monthly or quarterly topographic beach surveys and quarterly bathymetry to evaluate sediment volume changes
Seasonal SIO LiDAR surveys of Carlsbad beaches if continued
Agua Hedionda Lagoon monitoring
Potential Buena Vista Lagoon monitoring
Historical and ongoing beach surveys (SANDAG’s regional shoreline monitoring program, historical airborne lidar, etc).
Oceanographic Analysis 3 Evaluate changes in wave and currents
Waves
Currents
Monitor wave energy and nearshore currents
Argus video
CDIP buoys
SIO MOP Data
Recreational Impacts 4 Evaluate recreational benefits and/or impacts
Surfing conditions
Rip currents
Changes in days beach accessible
Video monitoring of surf conditions, number of people in the water and on beach
Surfline daily reports and cameras
Community monitoring program if continued
Monitoring
question
this helps
inform?
Monitoring Goal Metric/Analysis Monitoring
Approach
Potential leveragedresources
Extreme Event 3 Evaluate beach Change in beach Post event CDIP buoysMonitoringandbackshoresandvolumetopographic
response to large and/or beach survey
coastal events to width SIC—MOP Data
determine Post event
performance Of Wave runup and community-Surfllne Camerasstrateglesand..additional overtopplng beach WIdth
nourishment!surveys Lifeguard
maintenance Comparative Logs/Reports
needs response to other Post storm field
north county inspection to If continued the
beaches dorcutmentt piloted community-led
Eng/e131?!:10)program could beEvidenceoffloodiap9'expanded to also
overtopping,backshore conduct post-event
flooding,and erosion and monitoring of beach
backshore infrastructure WIdth'damage damage
Argus Video
Downdrift 2 Evaluate Compare Monthly or Seasonal SIO LiDAR
Impacts sediment sediment quarterly surveys of Carlsbad
downdrift impacts accretion on topographic beaches if continued
adjacent beach surveys
beaches,and quarterly .Evaluate sand .offshore,sand bathymetry to Agua Hedlon-da-source Impacts (If source locations evaluate Lagoon monltorlng
applicable)(if applicable),sediment volume
and around the Changes Potential Buena VistaharbormouthLagoonmonitoring
Historical and ongoing
beach surveys
(SANDAG’s regional
shoreline monitoring
program,historical
airborne lidar,etc).
Oceanographic 3 Evaluate Waves Monitor wave CDIP buoys
Analysis changes in wave energy and
and currents Currents gfififrflgre SIO MOP Data
Argus video
Recreational 4 Evaluate Surfing Video monitoring Surfline daily reports
Impacts recreational conditions of surf conditions,and cameras
benefits and/or
impacts Rip currents
Changes in days
beach accessible
number of people
in the water and
on beach Community monitoring
program if continued
—)The Power of Commitment
11213025 5Jan. 4, 2022 Item 4 Page 176 of 229
The Power of Commitment
11213025 6
Name Monitoring question this helps inform?
Monitoring Goal Metric/ Analysis Monitoring Approach Potential leveraged resources
Changes in monthly average beach area (towel availability)
Monthly or topographic beach surveys
Lifeguard rip current monitoring
Community-led monthly surveys of beach width and days when beach completely submerged
4.2 Example of Scientific Monitoring Strategies:
4.2.1 Sand Retention Pilot Project:
• Quarterly topographic surveys (lidar) from Oceanside Harbor to Tamarack Beach
• Quarterly bathy Harbor to Buena Vista Lagoon, transects spaced max 200 m apart. Should include
harbor mouth area. (Figure 3)
• Monthly topographic surveys Harbor to Buena Vista Lagoon
• Post storm event topographic monitoring and field inspection
• Offshore in situ current monitoring
• Argus video monitoring
4.2.2 Sand Replenishment Project:
• Quarterly topographic surveys (lidar) from Harbor to Tamarack
• Quarterly topographic surveys (lidar) from Santa Margarita River to Harbor – If sand is sourced from
Camp Pendleton
• Quarterly bathy Harbor to Buena Vista Lagoon, transects spaced max 200 m apart. Should include
harbor mouth area (Figure 3).
• Monthly topographic surveys Harbor to Buena Vista Lagoon
• Post storm event topographic monitoring and field inspection
• Pre and post topographic monitoring during sand shifting operations
• Offshore in situ current monitoring
• Argus video monitoring
Monitoring Monitoring Goal Metric/Analysis Monitoring Potential leveraged
question Approach resources
this helps
inform?
Monthly or
Changes in topographicmonthlyaveragebeachsurveys
beach area
(tovvel __Lifeguard ripavallablllty)current
monitoring
Community-led
monthly surveys
of beach width
and days when
beach completely
submerged
4.2 Example of Scientific Monitoring Strategies:
4.2.1 Sand Retention Pilot Project:
0 Quarterly topographic surveys (Iidar)from Oceanside Harbor to Tamarack Beach
0 Quarterly bathy Harbor to Buena Vista Lagoon,transects spaced max 200 m apart.Should include
harbor mouth area.(Figure 3)
0 Monthly topographic surveys Harbor to Buena Vista Lagoon
0 Post storm event topographic monitoring and field inspection
0 Offshore in situ current monitoring
0 Argus video monitoring
4.2.2 Sand Replenishment Project:
0 Quarterly topographic surveys (Iidar)from Harbor to Tamarack
0 Quarterly topographic surveys (Iidar)from Santa Margarita River to Harbor —If sand is sourced from
Camp Pendleton
0 Quarterly bathy Harbor to Buena Vista Lagoon,transects spaced max 200 m apart.Should include
harbor mouth area (Figure 3).
0 Monthly topographic surveys Harbor to Buena Vista Lagoon
0 Post storm event topographic monitoring and field inspection
0 Pre and post topographic monitoring during sand shifting operations
0 Offshore in situ current monitoring
0 Argus video monitoring
—)The Power of Commitment
11213025 6Jan. 4, 2022 Item 4 Page 177 of 229
The Power of Commitment
11213025 7
Figure 3 Survey transects used for the SIO January 2021 bathymetric survey.
4.3 Annual Harbor Dredging and Additional Considerations:
The US Army Corps of Engineers dredges the Oceanside harbor to maintain safe vessel passage and typically
places the dredged sand on the beaches south of the pier. The volume of dredge material varies but averages
approximately 250,000 cubic yards per year (Figure 4). The City of Oceanside should coordinate with the US
Army Corps of Engineers to develop a strategic approach for sand placement that compliments the potential
groin and sand-shifting projects. For example, dredged sediment could help offset potential negative groin
impacts identified through the monitoring program. Topographic and bathymetric surveys should be
coordinated with the US Army Corps of Engineers dredging schedules to assist in monitoring placed dredged
material and could also help inform dredge operations.
Figure 4 Annual sand bypassing at Oceanside Harbor
Ocsmsld J lube surveyLines,2021
Figure 3 Survey transects used for the SIO January 2021 bathymetric survey.
4.3 Annual Harbor Dredging and Additional Considerations:
The US Army Corps of Engineers dredges the Oceanside harbor to maintain safe vessel passage and typically
places the dredged sand on the beaches south of the pier.The volume of dredge material varies but averages
approximately 250,000 cubic yards per year (Figure 4).The City of Oceanside should coordinate with the US
Army Corps of Engineers to develop a strategic approach for sand placement that compliments the potential
groin and sand-shifting projects.For example,dredged sediment could help offset potential negative groin
impacts identified through the monitoring program.Topographic and bathymetric surveys should be
coordinated with the US Army Corps of Engineers dredging schedules to assist in monitoring placed dredged
material and could also help inform dredge operations.
Annual Oceanside Harbor Sand Bypassing
E:1:\\A
Emmi HIM.M A /\gmml [Vii /\/\\/‘>l_\/V \r v
ezeeeeeeeeeeee%*e%%%%%%%°¢°¢%%%
—AVEIage —Annual Harbor Sand Bypassing Volumes
Avg.”250,000 CY/YR
Figure 4 Annual sand bypassing at Oceanside Harbor
—)The Power of Commitment
11213025 7Jan. 4, 2022 Item 4 Page 178 of 229
August 11, 2021
Jan. 4, 2022 Item 4 Page 179 of 229
Background
Oceanside has a 79-year history of beach
erosion starting with construction of Camp
Pendleton Harbor in 1942.
Oceanside has been losing its shoreline for
years.
Lost shoreline at a rate of 3 feet per year on
average.
Below baseline beach width from 20 years ago.
Sand nourishment alone is not working.
Jan. 4, 2022 Item 4 Page 180 of 229
Background
Study was initiated to identify feasible solutions
to protect the beach from long-term erosion by:
Utilizing re-nourishment projects of beach suitablesands
Construction of retention devices to retain/reducelossofsand
Goal of the study was to identify strategies thatareenvironmentallysensitive,financially feasibleandthathaveareasonablechanceofbeingapprovedthroughtheregulatorypermittingprocess.
Jan. 4, 2022 Item 4 Page 181 of 229
Background
Study was initiated with the review and analysis ofrelevantglobalprojects.
Six concepts were put through a multi-criteriadecisionmatrixandranked.Matrix considered:
Downdrift impacts
Nearshore reef impacts
Sea level rise resilience
Estimated construction costs
Life cycle costs
Surfing impacts
Aesthetic impacts
Concepts were narrowed down to 1 option from eachcategory(retention and replenishment).
Jan. 4, 2022 Item 4 Page 182 of 229
Background
Concerns we’ve heard to date:
Pilot location
Schedule/Phasing
Downdrift impacts
Surfing impacts
Coastal management precedent
Resiliency of project to sea level rise
Jan. 4, 2022 Item 4 Page 183 of 229
Summary
The results shared tonight are not new ideas.
Groins have been considered a viable option for
Oceanside in several previous reports and
publications over the years.
At our 2nd Public Workshop,with ~200 in
attendance,73%were in favor of groins as the
preferred sand retention option.
Jan. 4, 2022 Item 4 Page 184 of 229
Sustaining our communities GHD
Analysis
1.Coastal Challenges
2.Nourishment & Retention Options
3.Option Performance & Scoring
4.Sand Distribution Options
5.Summary of Findings
Jan. 4, 2022 Item 4 Page 185 of 229
Sustaining our communities GHD
Coastal Challenges
1.Harbor Complex & Sediment Gradation
2.Limited Beach Gains from USACE Harbor
Dredging
3.Poor Performance of Regional Beach Fills
4.Difficulty Reaching Social, Political &
Regulatory Consensus
Jan. 4, 2022 Item 4 Page 186 of 229
Challenge 1: Harbor Complex & Sediment Gradation
400
450
500
550
600
650
700
750
800
850
900
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240Shoreline Position (m)
1934 Survey
1998 Survey
2006 Survey
Seawall
Pier SLR Groin Harbor
Erosion Accretion
(Source: USACE 2015)
(Source: Google Inc.)Jan. 4, 2022 Item 4 Page 187 of 229
Challenge 1: Harbor Complex & Sediment Gradation
Jan. 4, 2022 Item 4 Page 188 of 229
Challenge 2: Limited Gains from Harbor Dredging
Jan. 4, 2022 Item 4 Page 189 of 229
Harbor Dredged
March-May
Avg. = 253,000 CY
Sand Placement
Locations
Net Longshore Current
April -October
Challenge 2: Limited Gains from Harbor Dredging
Jan. 4, 2022 Item 4 Page 190 of 229
Challenge 3: Poor Performance of Regional Beach Fills
Warm Water Jetties
Cool Water Jetties
Regional Beach Sand Projects I & II (2001 & 2012)
(source: SANDAG)
Jan. 4, 2022 Item 4 Page 191 of 229
Carlsbad Benefits from Sand Retention Structure
0
50
100
150
200
250
1990 1995 2000 2005 2010 2015 2020MSL Beach WidthYear
Tamarack Beach (Profile CB-840)
Agua Hedionda Lagoon
Tamarack State Beach
Warm Water Jetties
Cool Water Jetties
3.6 ft/yr since 1990
Challenge 3: Poor Performance of Regional Beach Fills
Jan. 4, 2022 Item 4 Page 192 of 229
Challenge #4: Difficulty Reaching Social, Political & Regulatory Consensus
Experimental Sand Bypass
Preferred Groin Option
Jan. 4, 2022 Item 4 Page 193 of 229
Challenge #4: Difficulty Reaching Social, Political & Regulatory Consensus
(Photo: Russ Cunningham)
(Source: ESA 2019)
Jan. 4, 2022 Item 4 Page 194 of 229
Project Phasing
•Start with Pilot Project (location TBD)
•Robust scientific monitoring
•Learn and adapt (if needed)
•Scale with success
Design, permitting and outreach Build phase 1 Adapt & expand
2021 ~2025 ~2030
Jan. 4, 2022 Item 4 Page 195 of 229
Key Components:
•Change in beach width or volume
(compared to baseline conditions)
•Downdrift impacts
•Response to storm events
•Recreation impacts
Monitoring Tools:
•GPS
•Lidar & Nearshore Tools
•Video
•Citizen Science
•Field Inspection & Documentation
Scientific Monitoring Plan
Jan. 4, 2022 Item 4 Page 196 of 229
Project Alternatives
1.Beach Nourishment
2.Groin Pilot
3.South Jetty Extension
4.Reef Pilot
No Project –Used for comparative
purposes
Jan. 4, 2022 Item 4 Page 197 of 229
Pilot Reach TBD
Study assumptions
•4,000 ft shoreline length
•1,200 ft spacing for retention structures
Pilot location based on:
•Community outreach
•Regulatory considerations
•Logistics & economics Representative Pilot Reach Jan. 4, 2022 Item 4 Page 198 of 229
Alt. 1.Beach Nourishment
Features:
•300k CY every 5 years
•Footprint Identical to RBSP II (2012)
•$28M Lifecycle costs (20yr period)
Sand Fillet Considerations:
•Limited creation of a dry beach
•No downdrift impacts
Jan. 4, 2022 Item 4 Page 199 of 229
Alt. 2.Groins
Sand Fillet Sand Fillet Features:
•Four, 600’ long rock groins
•Beach nourishment (300k cy initially,
150k cy renourishment)
•$51M Lifecycle costs (20yr period)
Considerations:
•Downdrift impacts –optimize prefill & bypass
volumes
•Surfing impacts –monitoring surfing
•Lateral access –incorporated into design
•Nearshore currents –rips likely Jan. 4, 2022 Item 4 Page 200 of 229
Alt. 3.South Jetty Extension
Sand Fillet Sand Fillet
Features:
•350’ rock groin extension
•300k CY beach nourishment (300k cy
renourishment cycles)
•$36M Lifecycle costs (20yr period)
Considerations:
•Performance of beach fill
•Sand bypass needed
•Potential for surfing impacts at known resource Jan. 4, 2022 Item 4 Page 201 of 229
Alt. 4 Multi-Purpose Art. Reef
4:1
Emergent Crest
Waves Shoal
on Edges
Submerged Crests
Waves Reflect
in Center
Features:
•2 emergent, rubble mound breakwaters with submerged
edges –1,000 ft long
•Beach nourishment (300k CY pre-fill, 150k CY
renourishment)
•$148M Lifecycle costs (20yr period)
Considerations:
•Unproven design –surfing improvements not
a guarantee
•Downdrift impacts
•Nearshore currents –rips likely Jan. 4, 2022 Item 4 Page 202 of 229
Numerical Modeling Summary
•RBSP II validation
•Key question: How would have
beach performed if retention was
in place?
•Full-scale Scenario
•Beach Nourishment (RBSP II)
•Groins
•Reefs
•Pilot scale
•Groins
•Reefs
4:1
Submerged Crests
+175% volume compared to NOS
+185% volume compared to NOS
Nourishment Only Scenario (NOS)
Avg beach widths
of 100-200 ftJan. 4, 2022 Item 4 Page 203 of 229
Multi-Criteria Analysis (MCA)
4:1
Technical Performance (40%)
Creation/Restoration of
Beach 25%
Downdrift impacts 25%
Public Safety 25%
Sea Level Rise
Adaptability 25%
Financial (20%)
Lifecycle costs 70%
-Capital
-O&M (Renourishment)
-Adaptation (end of pilot)
In-direct economic benefits 30%
Environmental (40%)
Biological Resources 20%
Surfing Resources 20%
Aesthetics 20%
Beach Recreation 20%
Coastal Access 20%
100%0 Total Score
40%20%40%
Technical Performance Financial Environmental
Jan. 4, 2022 Item 4 Page 204 of 229
Overall MCA Score
4:1
Submerged Crests
8%
24%
30%
24%
30%
15%
16%
17%
14%
8%
10%
24%
34%
24%
35%
NO PROJECT
BEACH NOURISHMENT
GROINS
SLR GROIN
MODIFICATIONS
MULTI-PURPOSE REEFS
TECHNICAL PERFORMANCE (40%)FINANCIAL (20%)ENVIRONMENTAL (40%)
81%
33%
64%
62%
73%
Jan. 4, 2022 Item 4 Page 205 of 229
Beach Width -Value Comparison
Jan. 4, 2022 Item 4 Page 206 of 229
Sand Distribution Options
1.Fixed Trestle Sand
Bypass
2.Semi-Fixed Sand
Bypass
3.USACE Piggyback
Jan. 4, 2022 Item 4 Page 207 of 229
Sand Distribution System
Sand Fillet Sand Fillet
Features:
•Multiple input/discharge points
•Reduce mob/de-mob costs for bypassing & dredging
•Improved public safety & beach access (no pipe)
Considerations:
•Difficult designing a one-size-fits-all system
•Capital cost vs. long-term savings
Jan. 4, 2022 Item 4 Page 208 of 229
Evaluation of Sand Distribution
Options
Semi-fixed System Corps Piggyback
Securing high-quality source of sand is key (i.e.MCB Camp Pendleton)
or
Jan. 4, 2022 Item 4 Page 209 of 229
Summary of Findings
Sand Fillet Sand Fillet
Oceanside’s Challenges:
1.Harbor Complex blocks coarse grained sand
2.Limited beach gains from USACE harbor dredging program
3.Poor performance of RBSP projects in Oceanside
4.Difficulty reaching consensus
Sand Retention Alternative Evaluation:
•Groin Pilot scored highest based on MCA analysis
•Recommend Groin option be carried forward to next phase
Sand Distribution Alternatives:
•A sustainable, high-quality source of sand is needed
Source: Surfline.com
Jan. 4, 2022 Item 4 Page 210 of 229
Recommendation
The results shared tonight are not new ideas.
Groins have been considered a viable option for
Oceanside in several previous reports and
publications over the years.
At our 2nd Public Workshop, with ~200 in attendance,
73% were in favor of groins as the preferred sand
retention option.
Jan. 4, 2022 Item 4 Page 211 of 229
Recommendation
Staff recommends that the City Council approve the
beach sand feasibility study report and direct staff to
move to the next phase of the project to include
design, permitting and environmental work for a
groin and bypass system pilot project.
Jan. 4, 2022 Item 4 Page 212 of 229
Extra Slides
Sand Fillet Sand Fillet
Jan. 4, 2022 Item 4 Page 213 of 229
Chronic Beach Erosion
421,000 CY293,000 CY(Source: CFC 2020)
~200,000 CY/YR FROM HARBOR
Jan. 4, 2022 Item 4 Page 214 of 229
The Oceanside Problem:Long-term Erosion
Jan. 4, 2022 Item 4 Page 215 of 229
Numerical Modeling Summary
•Pilot-Scale Model
•4 Groins
•Average beach widths in the
100-150 ft range
•Downdrift impacts
•Monitor & mitigate (Pilot)
•Model predictions limited
Jan. 4, 2022 Item 4 Page 216 of 229
Numerical Modeling Summary
•Pilot-Scale Model
•2 Multi-purpose Reefs
•Significant salient accretion
•Avg beach widths of ~200 ft
behind reefs
•Downdrift impacts
•Monitor & mitigate (Pilot)
•Model predictions limited
Jan. 4, 2022 Item 4 Page 217 of 229
Beach Width –How much?
Jan. 4, 2022 Item 4 Page 218 of 229
Multi-Criteria Analysis (MCA)
4:1
Submerged Crests
•11 criteria organized into 3
categories to reflect public
feedback
•Technical Performance
•Financial
•Environmental
Public Workshop #1 (September 15,2020)
Poll Question 6:
What project impacts are you most concerned
about?(Select up to three)
1. Downdrift erosion (31/65)
2.Sea level rise resilience (30/65)
3. Surfing related impacts (19/65)
4. Costs (17/65)
5. Public safety & access (14/65)
Jan. 4, 2022 Item 4 Page 219 of 229
Technical Performance
4:1
Submerged Crests
No Project
1) Beach Nourishment
2) Groins
3) SLRR Groin Mods
4) Multi-purpose Reefs
8%
24%
30%
24%
30%
Retention alternatives offer
longer-lasting beach width,
improve adaptability to SLR
Beach creation Downdrift Impacts Public Safety SLR Adaptability
0 40%
40% of total
Jan. 4, 2022 Item 4 Page 220 of 229
No Project
1) Beach Nourishment
2) Groins
3) SLRR Groin Mods
4) Multi-purpose Reefs
Financial
4:1
Submerged Crests
4:1
Submerged Crests
15%
16%
17%
14%
8%
Capital Renourishment (O&M)Adaptation In-direct benefits
0 20%
20% of total
In-direct economic benefits
Jan. 4, 2022 Item 4 Page 221 of 229
Environmental
4:1
Submerged Crests
4:1
Submerged Crests
No Project
1) Beach Nourishment
2) Groins
3) SLRR Groin Mods
4) Multi-purpose Reefs
10%
24%
34%
26%
35%
Retention alternatives offer
improved coastal access &
biological resource diversity
Biological Surfing Aesthetics Beach Recreation Coastal Access
0 40%
40% of total
Jan. 4, 2022 Item 4 Page 222 of 229
MCA Sensitivity
4:1
Submerged Crests
0%10%20%30%40%50%60%70%80%90%100%
Technical Performance 40%Financial 20%Environmental 40%
Technical Performance 60%Financial 20%Environmental 20%
Technical Performance 20%Financial 60%Environmental 20%
Technical Performance 20%Financial 20%Environmental 60%
Technical Performance 33.3%Financial 33.3%Environmental 33.3%
No Project
No Project
No Project
No Project
No Project
Beach Nourishment Progam
Beach Nourishment Progam
Beach Nourishment Progam
Beach Nourishment Progam
Beach Nourishment Progam
Groins
Groins
Groins
Groins
Groins
SLRR Groin Modifications
SLRR Groin Modifications
SLRR Groin Modifications
SLRR Groin Modifications
SLRR Groin Modifications
Multi-Purpose Artificial Reef
Multi-Purpose Artificial Reef
Multi-Purpose Artificial Reef
Multi-Purpose Artificial Reef
Multi-Purpose Artificial Reef
CATEGORY WEIGHTING SENSITIVITY ANALYSIS
Multi-Purpose Artificial Reef SLRR Groin Modifications Groins Beach Nourishment Progam No Project
Jan. 4, 2022 Item 4 Page 223 of 229
Alt. 1.Fixed Trestle Bypass
Features:
•Fixed trestle (pier) on MCB Camp Pendleton &
series of underground distribution pipelines
•HDD under known constriction points
•100-300k CY/YR of sand
•Approx. $36M (initial), $5.2M/YR (O&M)
Considerations:
•Expensive to construct & operate
•Construction of infrastructure on MCB Camp
Pendleton
•Risk of low recharge of sand at fixed location
Jan. 4, 2022 Item 4 Page 224 of 229
Alt. 2.Semi-Fixed Bypass
Sand Fillet Sand Fillet Features:
•Sandshifter or crane manipulated hydraulic dredge
system with distribution pipelines
•50-100k CY/YR of sand
•Approx. ~$11M (initial), $0.2M/YR (O&M)
Considerations:
•Scaling of annual sand bypass volume with need
•Ability to move system –mitigate sand recharge risk
•Requires MCB Camp Pendleton Cooperation
Jan. 4, 2022 Item 4 Page 225 of 229
Alt. 3.USACE Piggyback
Sand Fillet Sand Fillet Features:
•Build sand distribution pipelines only for Corps & City
use in dredging projects
•50-100k CY/YR of sand
•Approx. $9M (initial), $0.2M/YR (O&M)
Considerations:
•Save mob/demob costs
•Public safety benefit during construction-limited pipe
•Scaling of annual sand bypass volume with need
•Requires MCB Camp Pendleton Cooperation Jan. 4, 2022 Item 4 Page 226 of 229
Scientific Baseline Survey –Jan. 2021
Jan. 4, 2022 Item 4 Page 227 of 229
Scientific Baseline Survey -Jan. 2021
Jan. 4, 2022 Item 4 Page 228 of 229
Citizen Science
Jan. 4, 2022 Item 4 Page 229 of 229