HomeMy WebLinkAboutAMEND 2018-0003; COASTLINE COMMUNITY CHURCH - 1ST AMENDMENT; PRELIMINARY STORM WATER QUALITY MANAGEMENT PLAN; 2019-01-16CITY OF CARLSBAD
PRIORITY DEVELOPMENT PROJECT (PDP) PRELIMINARY
STORM WATER QUALITY MANAGEMENT PLAN (SWQMP)
FOR
COASTLINE COMMUNIT CHURCH
PROJECT ID#AMEND2018-0003
ENGINEER OF WORK:
NG, RCE 36083
PREPARED FOR:
COASTLINE COMMUNITY CHURCH
2215 CALLE BARCELONA CARLSBAD,
CA 92009
(760) 753-0886
PREPARED BY:
FUSCOE ENGINEERING, INC.
6390 GREENWICH DRIVE
SAN DIEGO, CA 92122
858-554-1500
DATE:
JANUARY 16, 2019
1
RECEIVED
JAN 1 7 2019
CITY OF CARLSBAD
PLANNING DIVISION
c-
r ..
TABLE OF CONTENTS
Certification Page
Project Vicinity Map
FORM E-34 Storm Water Standard Questionnaire
Site Information
FORM E-36 Standard Project Requirement Checklist
Summary of PDP Structural BMPs
Attachment 1 : Backup for PDP Pollutant Control BMPs
Attachment 1 a: DMA Exhibit
• Existing Impervious Area Exhibit
Attachment 1 b: Tabular Summary of DMAs and Design Capture Volume Calculations
Attachment 1 c: Harvest and Use Feasibility Screening (when applicable)
Attachment 1d: Categorization of Infiltration Feasibility Condition (when applicable)
Attachment 1 e: Pollutant Control BMP Design Worksheets / Calculations:
• Worksheet B.5-1: BMP Sizing Worksheet
• Worksheet B.5-3: County Alternate Minimum Biofiltration Footprint Ratio
• San Diego County Rainfall 30 Year Annual Average Map
• BMP Sizing Spreadsheet V2.0 for Hydromod Sizing
• BMP-1 Volume Size Verification
• BMP Drawdown Calculations
Attachment 2: Backup for PDP Hydromodification Control Measures
Attachment 2a: Hydromodification Management Exhibit
Attachment 2b: Management of Critical Coarse Sediment Yield Areas
Attachment 2c: Geomorphic Assessment of Receiving Channels
Attachment 2d: Flow Control Facility Design
Attachment 3: Structural BMP Maintenance Thresholds and Actions
Attachment 4: Single Sheet BMP (SSBMP) Exhibit
2
C ..
CERTIFICATION PAGE
Project Name: Coastline Community Church
Project ID: AMEND2018-0003
I hereby declare that I am the Engineer in Responsible Charge of design of storm water BMPs for
this project, and that I have exercised responsible charge over the design of the project as defined
in Section 6703 of the Business and Professions Code, and that the design is consistent with the
requirements of the BMP Design Manual, which is based on the requirements of SDRWQCB
Order No. R9-2013-0001 (MS4 Permit) or the current Order.
I have read and understand that the City Engineer has adopted minimum requirements for
managing urban runoff, including storm water, from land development activities, as described in
the BMP Design Manual. I certify that this SWQMP has been completed to the best of my ability
and accurately reflects the project being proposed and the applicable source control and site
design BMPs proposed to minimize the potentially negative impacts of this project's land
development activities on water quality. I understand and acknowledge that the plan check review
of this SWQMP by the City Engineer is confined to a review and does not relieve me, as the
Engineer in Responsible Charge of design of storm water BMPs for this project, of my
responsibilities for pr 1ect design.
ber & Expiration Date
Eric Armstrong, PE
Print Name
Fuscoe Engineering, Inc.
Company
Date
[/17 ft~
3
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PROJECT VICINITY MAP
VICINITY MAP
NOT TO SCALE
CITY Of OCEANSIDE ,..,
PACIFIC
4
SITE
(
[Insert City's Storm Water Standard Questionnaire (Form E-34) here]
..
(
5
{ City of
Carlsbad
STORM WATER STANDARDS
QUESTIONNAIRE
Development Services
Land Development Engineering
1635 Faraday Avenue
(760) 602-2750
www.carlsbadca.gov
E-34
I INSTRUCTIONS:
To address post-development pollutants that may be generated from development projects, the city requires that new
development and significant redevelopment priority projects incorporate Permanent Storm Water Best Management
Practices (BMPs) into the project design per Carlsbad BMP Design Manual (BMP Manual). To view the BMP Manual,
refer to the Engineering Standards (Volume 5).
This questionnaire must be completed by the applicant in advance of submitting for a development application
(subdivision, discretionary permits and/or construction permits). The results of the questionnaire determine the level of
storm water standards that must be applied to a proposed development or redevelopment project. Depending on the
outcome, your project will either be subject to 'STANDARD PROJECT' requirements or be subject to 'PRIORITY
DEVELOPMENT PROJECT' (PDP) requirements.
Your responses to the questionnaire represent an initial assessment of the proposed project conditions and impacts. City
staff has responsibility for making the final assessment after submission of the development application . If staff
determines that the questionnaire was incorrectly filled out and is subject to more stringent storm water standards than
initially assessed by you, this will result in the return of the development application as incomplete. In this case, please
make the changes to the questionnaire and resubmit to the city.
If you are unsure about the meaning of a question or need help in determining how to respond to one or more of the
questions, please seek assistance from Land Development Engineering staff.
completed and signed questionnaire must be submitted with each development project application. Only one
completed and signed questionnaire is required when multiple development applications for the same project are
submitted concurrently.
PROJECT INFORMATION
PROJECT NAME: COASTLINE COMMUNITY CHURCH PROJECT ID: AMEND2018-0003
ADDRESS: 2215 CALLE BARCELONA, CARLSBAD, CA 92009 APN: 255-273-07-00
The project is (check one): D New Development Ill Redevelopment
The total proposed disturbed area is: 125,346 ft2(2.9 ) acres
The total proposed newly created and/or replaced impervious area is: 58,536 ft2 ( 1.344 ) acres
If your project is covered by an approved SWQMP as part of a larger development project, provide the project ID and the
SWQMP # of the larger development project:
Project ID SWQMP#:
Then, go to Step 1 and follow the instructions. When completed, sign the form at the end and submit this with your
application to the city.
E-34 Page 1 of 4 REV 02/16
STEP1
TO BE COMPLETED FOR ALL PROJECTS
1o determine if your project is a "development project", please answer the following question:
YES NO
~Is your project LIMITED TO routine maintenance activity and/or repair/improvements to an existing building
or structure that do not alter the size (See Section 1.3 of the BMP Design Manual for guidance)? □ [l]
If you answered "yes" to the above question, provide justification below then go to Step 5, mark the third box stating "my
project is not a 'development project' and not subject to the requirements of the BMP manual" and complete applicant
information.
Justification/discussion: (e.g. the project includes only interior remodels within an existing building):
If you answered "no" to the above question, the project is a 'development proiect', go to Step 2.
STEP2
TO BE COMPLETED FOR ALL DEVELOPMENT PROJECTS
To determine if your project is exempt from PDP requirements pursuant to MS4 Permit Provision E.3.b.(3), please answer
the following questions:
·~ your project LIMITED to one or more of the following:
YES NO
1. Constructing new or retrofitting paved sidewalks, bicycle lanes or trails that meet the following criteria:
a) Designed and constructed to direct storm water runoff to adjacent vegetated areas, or other non-
erodible permeable areas; □ [l] b) Designed and constructed to be hydraulically disconnected from paved streets or roads;
c) Designed and constructed with permeable pavements or surfaces in accordance with USEPA
Green Streets Quidance?
2. Retrofitting or redeveloping existing paved alleys, streets, or roads that are designed and constructed in □ [l] accordance with the USEPA Green Streets guidance?
3. Ground Mounted Solar Array that meets the criteria provided in section 1.4.2 of the BMP manual? □ [l]
If you answered "yes" to one or more of the above questions, provide discussion/justification below, then go to Step 5, mark
the second box stating "my project is EXEMPT from PDP ... " and complete applicant information.
Discussion to justify exemption ( e.g. the project redeveloping existing road designed and constructed in accordance with
the USEPA Green Street guidance):
The project proposes to construct a building in place of an existing building, and expand the parking lot.
'-
I
11. _rou answered "no" to the above questions, your oroiect is not exempt from PDP, go to Step 3.
E-34 Page 2 of 4 REV 02/16
STEP3
TO BE COMPLETED FOR ALL NEW OR REDEVELOPMENT PROJECTS
To determine if your project is a PDP, please answer the following questions (MS4 Permit Provision E.3.b.(1 )):
YES NO
1. Is your project a new development that creates 10,000 square feet or more of impervious surfaces
collectively over the entire project site? This includes commercial, industrial, residential, mixed-use, □ [l]
and public development projects on public or private land.
2. Is your project a redevelopment project creating and/or replacing 5,000 square feet or more of
impervious surface collectively over the entire project site on an existing site of 10,000 square feet or [l] □ more of impervious surface? This includes commercial, industrial, residential, mixed-use, and public
development projects on public or private land.
3. Is your project a new or redevelopment project that creates and/or replaces 5,000 square feet or more
of impervious surface collectively over the entire project site and supports a restaurant? A restaurant is
a facility that sells prepared foods and drinks for consumption, including stationary lunch counters and □ [l]
refreshment stands selling prepared foods and drinks for immediate consumption (Standard Industrial
Classification (SIC) code 5812).
4. Is your project a new or redevelopment project that creates 5,000 square feet or more of impervious
surface collectively over the entire project site and supports a hillside development project? A hillside □ [l]
development proiect includes development on any natural slope that is twenty-five percent or greater.
5. Is your project a new or redevelopment project that creates and/or replaces 5,000 square feet or more
of impervious surface collectively over the entire project site and supports a parking lot? A parking lot is □ [l] a land area or facility for the temporary parking or storage of motor vehicles used personally for
business or for commerce.
6. Is your project a new or redevelopment project that creates and/or replaces 5,000 square feet or more
of impervious surface collectively over the entire project site and supports a street, road , highway □ [l] freeway or driveway? A street, road, highway, freeway or driveway is any paved impervious surface
used for the transportation of automobiles, trucks, motorcycles, and other vehicles.
7 Is your project a new or redevelopment project that creates and/or replaces 2,500 square feet or more
,,_/
of impervious surface collectively over the entire site, and discharges directly to an Environmentally
Sensitive Area (ESA)? "Discharging Directly to" includes flow that is conveyed overland a distance of □ [l]
200 feet or less from the project to the ESA, or conveyed in a pipe or open channel any distance as an
isolated flow from the project to the ESA (i.e. not commingled with flows from adjacent lands).*
8. Is your project a new development or redevelopment project that creates and/or replaces 5,000 square
feet or more of impervious surface that supports an automotive repair shop? An automotive repair □ [l] shop is a facility that is categorized in any one of the following Standard Industrial Classification (SIC)
codes: 5013, 5014, 5541, 7532-7534, or 7536-7539.
9. Is your project a new development or redevelopment project that creates and/or replaces 5,000 square
feet or more of impervious area that supports a retail gasoline outlet (RGO)? This category includes □ Ill RGO's that meet the following criteria: (a) 5,000 square feet or more or (b) a project Average Daily
Traffic (ADT) of 100 or more vehicles per day.
10. Is your project a new or redevelopment project that results in the disturbance of one or more acres of land Ill □ and are expected to generate pollutants post construction?
11. Is your project located within 200 feet of the Pacific Ocean and (1) creates 2,500 square feet or more of
impervious surface or (2) increases impervious surface on the property by more than 10%? (CMG □ Ill
21.203.040)
If you answered "yes" to one or more of the above questions, your project is a PDP. If your project is a redevelopment
project, go to step 4. If your project is a new project, go to step 5, check the first box stating "My project is a PDP ... "
and complete applicant information.
If you answered "no" to all of the above questions, your project is a 'STANDARD PROJECT.' Go to step 5, check the
second box statinq "My project is a 'STANDARD PROJECT' ... " and complete applicant information.
E-34 Page 3 of 4 REV 02/16
STEP4
TO BE COMPLETED FOR REDEVELOPMENT PROJECTS THAT ARE PRIORITY DEVELOPMENT PROJECTS (PDP)
ONLY
)mplete the questions below regarding your redevelopment project (MS4 Permit Provision E.3.b.(2)): -YES NO
Does the redevelopment project result in the creation or replacement of impervious surface in an amount
of less than 50% of the surface area of the previously existing development? Complete the percent
impervious calculation below:
Existing impervious area (A) = 118,624 sq. ft. Ill □
Total proposed newly created or replaced impervious area (8) = 58,536 sq. ft.
Percent impervious area created or replaced (B/A)*100 = 49·3 %
If you answered "yes", the structural BMPs required for PDP apply only to the creation or replacement of impervious
surface and not the entire development. Go to step 5, check the first box stating "My project is a PDP ... " and complete
applicant information.
If you answered "no," the structural BM P's required for PDP apply to the entire development. Go to step 5, check the
check the first box stating "My project is a PDP ... " and complete aoolicant information.
STEPS
CHECK THE APPROPRIATE BOX AND COMPLETE APPLICANT INFORMATION
Ill My project is a PDP and must comply with PDP stormwater requirements of the BMP Manual. I understand I must
prepare a Storm Water Quality Management Plan (SWQMP) for submittal at time of application.
0 My project is a 'STANDARD PROJECT' OR EXEMPT from PDP and must only comply with 'STANDARD PROJECT'
stormwater requirements of the BMP Manual. As part of these requirements, I will submit a "Standard Project
Requirement Checklist Form E-36" and incorporate low impact development strategies throughout my project.
lllote: For projects that are close to meeting the PDP threshold, staff may require detailed impervious area calculations
d exhibits to verify if 'STANDARD PROJECT' stormwater requirements apply.
0 My Project is NOT a 'development project' and is not subject to the requirements of the BMP Manual.
Applicant Information and Signature Box
Applicant Name: JIM GRANT Applicant Title: PRESIDENT
Applicant Signature: w~ f ~ ~ate: 12/20/2018
.. • Environmentally Sensitive Areas include but are not hm1ted to all Clean Water Act Section 303(d) impaired water bodies; areas designated as Areas of Special
Biological Significance by the State Water Resources Control Board (Water Quality Control Plan for the San Diego Basin (1 994) and amendments); water bodies
designated with the RARE beneficial use by the State Water Resources Control Board (Water Quality Control Plan for the San Diego Basin (1994) and
amendments); areas designated as preserves or their equivalent under the Multi Species Conservation Program within the Cities and County of San Diego; Habitat
Management Plan; and any other equivalent environmentally sensitive areas which have been identified by the City.
Th" B fi c·t U O I IS ox or 1:y se nry
YES NO
City Concurrence: □ □
By:
Date:
Project ID:
E-34 Page 4 of 4 REV 02/16
SITE INFORMATION CHECKLIST
Project Summary Information
Project Name Coastline Community Church
Project ID xxxx
Project Address 2215 Calle Barcelona
Carlsbad, CA 92009
Assessor's Parcel Number(s) (APN(s)) 255-273-07-00
Project Watershed (Hydrologic Unit) Carlsbad 904
Parcel Area
6.43 Acres (280,090 Square Feet)
Existing Impervious Area 2.72 Acres (1 18,624 Square Feet) (subset of Parcel Area)
Area to be disturbed by the project
2.88 Acres ( 125,346 Square Feet) (Project Area)
Project Proposed Impervious Area
1.344 Acres (58,536 Square Feet) (subset of Project Area)
Project Proposed Pervious Area
1.52 Acres ( 66,810 Square Feet) (subset of Project Area)
Note: Proposed Impervious Area + Proposed Pervious Area = Area to be Disturbed by the
Project.
This may be less than the Parcel Area.
6
Description of Existing Site Condition and Drainage Patterns
Current Status of the Site (select all that apply):
x Existing development
J Previously graded but not built out
J Agricultural or other non-impervious use
J Vacant, undeveloped/natural
Description / Additional Information:
The project area currently consists of existing buildings, parking, and a playground. The site is
currently zoned for religious purposes.
Existing Land Cover Includes (select all that apply):
x Vegetative Cover
J Non-Vegetated Pervious Areas
x Impervious Areas
Description / Additional Information:
Existing pervious features of the site include landscape, vegetated areas, playground, and
compacted native material. Impervious features of the site include buildings, sidewalks, roadway,
and parking.
Underlying Soil belongs to Hydrologic Soil Group (select all that apply):
J NRCS Type A
J NRCS Type B
J NRCS Type C
x NRCS Type D
The site consists mainly of Type D Soils, and a small portion of the northeast corner of the site
consists of Type B Soils. Type D Soil will be used for design of the BMPs.
Approximate Depth to Groundwater (GW):
J GW Depth < 5 feet
J 5 feet < GW Depth < 1 0 feet
J 1 0 feet < GW Depth < 20 feet
x GW Depth > 20 feet
Existing Natural Hydrologic Features (select all that apply):
J Watercourses
J Seeps
J Springs
J Wetlands
x None
Description / Additional Information:
The site has been previously graded and developed, and there are no natural hydrologic features
within the site.
7
Description of Existing Site Topography and Drainage [How is storm water runoff conveyed from
the site? At a minimum, this description should answer (1) whether existing drainage
conveyance is natural or urban; (2) describe existing constructed storm water conveyance
systems, if applicable; and (3) is runoff from offsite conveyed through the site? if so, describe]:
The existing (graded) topography slopes generally to the north and northeast. Runoff flows to
the north via concrete brow ditches, swales, and a channel, and is collected in an existing
desilting basin located at the northwes corner of the site. A portion of runoff flows via surface
flow and gutter flow towards the northeast portion of the site, where it is collected by two catch
basins. It flows slightly northwest via a 24" RCP storm drain pipe to a cleanout modified to serve
as a low flow separator. Runoff then flows under Calle Barcelona via 24" and 36" RCP, and into
the tract to the Arroya La Costa development.
Offsite runoff from the south flows into a brow ditch that flows east to west along the southern
boundary of the site, and then flows north into the existing northwest detention basin, the flow is
then collected conveyed to the Arroya La Costa development via the existing 24" RCP.
8
Description of Proposed Site Development and Drainage Patterns
Project Description / Proposed Land Use and/or Activities:
The project proposes to construct buildings for services and classrooms, and parking.
List/describe proposed impervious features of the project (e.g., buildings, roadways, parking
lots, courtyards, athletic courts, other impervious features):
Proposed impervious features of the site include buildings, retaining wall, sidewalks, and parking.
List/describe proposed pervious features of the project (e.g., landscape areas):
Proposed pervious features of the site include permeable pavers, landscape, playground, and
the proposed water quality basin.
Does the project include grading and changes to site topography?
x Yes
J No
Description/ Additional Information:
The project will include grading for the parking lot and the new building, and proposed drainage
will remain similar to the current drainage patterns.
Does the project include changes to site drainage (e.g., installation of new storm water
conveyance systems)?
x Yes
J No
Description / Additional Information:
The project proposes to add storm drain, catch basins, and biofiltration basins.
9
Identify whether any of the following features, activities, and/or pollutant source areas will be
present (select all that apply):
x On-site storm drain inlets
J Interior floor drains and elevator shaft sump pumps
J Interior parking garages
J Need for future indoor & structural pest control
x Landscape/Outdoor Pesticide Use
J Pools, spas, ponds, decorative fountains, and other water features
J Food service
J Refuse areas
J Industrial processes
Outdoor storage of equipment or materials
J Vehicle and Equipment Cleaning
J Vehicle/Equipment Repair and Maintenance
J Fuel Dispensing Areas
J Loading Docks
J Fire Sprinkler Test Water
J Miscellaneous Drain or Wash Water
x Plazas, sidewalks, and parking lots
10
Identification of Receiving Water Pollutants of Concern
Describe path of storm water from the project site to the Pacific Ocean ( or bay, lagoon, lake or
reservoir, as applicable):
Runoff from the site flows to Batiquitos Lagoon, which then drains to the Pacific Ocean.
List any 303(d) impaired water bodies within the path of storm water from the project site to the
Pacific Ocean (or bay, lagoon, lake or reservoir, as applicable), identify the
pollutant(s)/stressor(s) causing impairment, and identify any TMDLs for the impaired water
bodies:
303(d) Impaired Water Body Pollutant( s )/Stressor( s) TMDLs
Encinitas Creek Benthic Commun ity Effects TMDL req'd
Phosphorous, Selenium, Toxicity rl"MDL req'd
Batiquitos Lagoon Toxicity TMDL req'd
Identification of Project Site Pollutants
Identify pollutants anticipated from the project site based on all proposed use(s) of the site (see
BMP Desiqn Manual Aooendix B.6):
Also a Receiving
Not Applicable to Anticipated from the Water Pollutant of
Pollutant the Project Site Project Site Concern
X
Sediment
X
Nutrients
X X
Heavv Metals
X
Orqanic Compounds
X
Trash & Debris
Oxygen Demanding X
Substances
X
Oil & Grease
X
Bacteria & Viruses .. X
Pesticides
11
Hydromodlficatlon Management Requirements
Do hydromodification management requirements apply (see Section 1.6 of the BMP Design
Manual)?
x Yes, hydromodification management flow control structural BMPs required.
J No, the project will discharge runoff directly to existing underground storm drains discharging
directly to water storage reservoirs, lakes, enclosed embayments, or the Pacific Ocean.
J No, the project will discharge runoff directly to conveyance channels whose bed and bank are
concrete-lined all the way from the point of discharge to water storage reservoirs, lakes,
enclosed embayments, or the Pacific Ocean.
J No, the project will discharge runoff directly to an area identified as appropriate for an
exemption by the WMAA for the watershed in which the project resides.
Description/ Additional Information (to be provided if a 'No' answer has been selected above):
Critical Coarse Sediment Yield Areas*
*This Section onlv reauired If hvdromodlflcation manaaement reaulrements annlv
Based on the maps provided within the WMAA, do potential critical coarse sediment yield areas
exist within the project drainage boundaries?
J Yes
x No: No critical coarse sediment yield areas to be protected based on WMAA maps
If yes, have any of the optional analyses presented in Section 6.2 of the BMP Design Manual
been performed?
J 6.2.1 Verification of Geomorphic Landscape Units (GLUs) Onsite
J 6.2.2 Downstream Systems Sensitivity to Coarse Sediment
J 6.2.3 Optional Additional Analysis of Potential Critical Coarse Sediment Yield Areas Onsite
J No optional analyses performed, the project will avoid critical coarse sediment yield areas
identified based on WMAA maps
If optional analyses were performed, what is the final result?
J No critical coarse sediment yield areas to be protected based on verification of GLUs onsite
J Critical coarse sediment yield areas exist but additional analysis has determined that
protection is not required. Documentation attached in Attachment 8 of the SWQMP.
J Critical coarse sediment yield areas exist and require protection. The project will implement
management measures described in Sections 6.2.4 and 6.2.5 as applicable, and the areas
are identified on the SWQMP Exhibit.
Discussion/ Additional Information:
NO CCSYAs exist within the project drainage boundary.
12
Flow Control for Post-Project Runoff"
*This Section only required If hydromodificatlon management requirements aooly
List and describe point(s) of compliance (POCs) for flow control for hydromodification
management (see Section 6.3.1 ). For each POC, provide a POC identification name or number
correlating to the project's HMP Exhibit and a receiving channel identification name or number
correlating to the project's HMP Exhibit.
There will be three POCs for hydromodification management. POC-1 will be located at the
northwest corner of the site. POC-1 is the discharge point of the proposed biofiltration basin to
the existing 24" storm drain running north of the site.
POC-2 will be located at the BMP-2 discharge point, and POC-3 will be located at the BMP-3
discharge point.
Has a geomorphic assessment been performed for the receiving channel(s)?
No, the low flow threshold is 0.102 (default low flow threshold)
J Yes, the result is the low flow threshold is 0.102
J Yes, the result is the low flow threshold is 0.302
X Yes, the result is the low flow threshold is 0.502
If a geomorphic assessment has been performed, provide title, date, and preparer:
Hydromodification Screening for La Costa Valley School Site Development,
!July 8, 2014, prepared by Chang Consultants
Discussion/ Additional Information: (optional)
The geomorphic assessment was prepared for the La Costa Valley School, located adjacent to
the project site (immediately east of the site). Both projects discharge to the channel, and the
results of the assessment indicate the low flow threshold is 0.502.
13
Other Site Requirements and Constraints
When applicable, list other site requirements or constraints that will influence storm water
management design, such as zoning requirements including setbacks and open space, or City
codes governing minimum street width, sidewalk construction, allowable pavement types, and
drainage requirements.
Optional Additional Information or Continuation of Previous Sections As Needed
This space provided for additional information or continuation of information from previous
sections as needed.
14
[Insert City's Standard Project Requirement Checklist Form E-36 (here)]
15
\(city of
Carlsbad
STANDARD PROJECT·
REQUIREMENT
CHECKLIST
E-36
Project lnfonnatlon
Project Name: COASTLINE COMMUNITY CHURCH
Project ID: AMEND2018-0003
DWG No. or Building Permit No.:
Source Control BMPs
Development Services
Land Development Engineering
1635 Faraday Avenue
(760) 602-2750
www.carlsbadca.gov
All development projects must implement source control BMPs SC-1 through SC-6 where applicable and feasible. See
Chapter 4 and Appendix E.1 of the BMP Design Manual for information to implement source control BMPs shown in this
checklist.
Answer each category below pursuant to the following.
• "Yes" means the project will implement the source control BMP as described in Chapter 4 and/or Appendix E.1 of the
Model BMP Design Manual. Discussion/justification is not required.
• "No" means the BMP is applicable to the project but it is not feasible to implement.
provided. Please add attachments if more space is needed.
Discussion/justification must be
• "N/A" means the BMP is not applicable at the project site because the project does not include the feature that is
addressed by the BMP (e.g., the project has no outdoor materials storage areas).
provided.
Discussion/justification may be
Source Control Requirement Applied?
L.sC-1 Prevention of Illicit Discharges into the MS4 Ill Yes □ No □ N/A
Jiscussion/justification if SC-1 not implemented:
SC-2 Storm Drain Stenciling or Signage Ill Yes □ No □ N/A
Discussion/justification if SC-2 not implemented:
SC-3 Protect Outdoor Materials Storage Areas from Rainfall, Run-On, Runoff, and Wind Ill Yes 0 No ON/A Dispersal
Discussion/justification if SC-3 not implemented:
E-36 Page 1 of 4 Revised 03/16
Source Control Reaulrement (continued) Annlled?
SC-4 Protect Materials Stored in Outdoor Work Areas from Rainfall, Run-On, Runoff, and
Wind Dispersal Ill Yes D No D N/A
Discussion/justification if SC-4 not implemented:
SC-5 Protect Trash Storage Areas from Rainfall, Run-On, Runoff, and Wind Dispersal Ill Yes D No D NIA
Discussion/justification if SC-5 not implemented:
SC-6 Additional BMPs based on Potential Sources of Runoff Pollutants must answer for each source listed below and
identify additional BMPs. (See Table in Appendix E.1 of BMP Manual for Quidance).
Ill On-site storm drain inlets 12!Yes D No D N/A
D Interior floor drains and elevator shaft sump pumps D Yes D No Ill N/A
D Interior parking garages D Yes D No Ill NIA
D Need for future indoor & structural pest control □ Yes D No Ill NIA
Ill Landscape/Outdoor Pesticide Use 121 Yes D No D NIA
D Pools, spas, ponds, decorative fountains, and other water features D Yes D No Ill N/A
(_) D Food service □ Yes D No Ill NIA
D Refuse areas □Yes D No Ill N/A
D Industrial processes D Yes D No Ill N/A
D Outdoor storage of equipment or materials D Yes D No Ill N/A
D Vehicle and Equipment Cleaning D Yes D No Ill NIA
D Vehicle/Equipment Repair and Maintenance D Yes D No Ill NIA
D Fuel Dispensing Areas D Yes D No Ill N/A
D Loading Docks D Yes D No Ill N/A
D Fire Sprinkler Test Water D Yes D No Ill NIA
D Miscellaneous Drain or Wash Water D Yes D No Ill N/A
121 Plazas, sidewalks, and parkinq lots 121Yes □ No □ N/A
For "Yes" answers, identify the additional BMP per Appendix E.1. Provide justification for "No" answers.
*For landscape/outdoor pesticide use, use CASQA BMP SC-41 , Building and Grounds Maintenance
*For plazas, sidewalks, and parking lots -areas will be swept regularly to prevent accumulation of debris and litter. Debris
from power washing shall be collected and washwater containing cleaning agent or degreaser shall be collected and
discharged into a sanitary sewer and not a storm drain .
....
E-36 Page 2 of 4 Revised 03/16
Site Design BMPs
All development projects must implement site design BMPs SD-1 through SD-8 where applicable and feasible. See
Chapter 4 and Appendix E.2 thru E.6 of the BMP Design Manual for information to implement site design BMPs shown in
this checklist.
-\nswer each category below pursuant to the following.
• "Yes" means the project will implement the site design BMPs as described in Chapter 4 and/or Appendix E.2 thru E.6 of
the Model BMP Design Manual. Discussion / justification is not required.
• "No" means the BMPs is applicable to the project but it is not feasible to implement. Discussion/justification must be
provided. Please add attachments if more space is needed.
• "N/A" means the BMPs is not applicable at the project site because the project does not include the feature that is
addressed by the BMPs (e.g., the project site has no existing natural areas to conserve). Discussion/justification may be
provided.
Source Control Requirement I Applied?
SD-1 Maintain Natural Drainaqe Pathways and Hydrologic Features I IZl Yes I □ No I □ N/A
Discussion/justification if SD-1 not implemented:
SD-2 Conserve Natural Areas, Soils, and Vegetation I IZl Yes I □ No I □ N/A
Discussion/justification if SD-2 not implemented:
~
SD-3 Minimize Impervious Area I IZl Yes I □ No I □ N/A
Discussion/justification if SD-3 not implemented:
SD-4 Minimize Soil Compaction I IZl Yes I □ No I D NIA
Discussion/justification if SD-4 not implemented:
SD-5 Impervious Area Dispersion I IZl Yes I □ No I □ N/A
Discussion/justification if SD-5 not implemented:
)
-
E-36 Page 3 of 4 Revised 03/16
Source Control Reaulrement (continued) I Annlled?
SD-6 Runoff Collection I IZI Yes I D No ID N/A
Discussion/justification if SD-6 not implemented:
SD-7 Landscaping with Native or Drought Tolerant Species I D Yes I D No I 1Z1 NIA
Discussion/justification if SD-7 not implemented:
SD-8 Harvesting and Using Precipitation I D Yes I D No I IZI N/A
Discussion/justification if SD-8 not implemented:
E-36 Page 4 of 4 Revised 03/16
SUMMARY OF PDP STRUCTURAL BMPS
PDP Structural BMPs
All PDPs must implement structural BMPs for storm water pollutant control (see Chapter 5 of
the BMP Design Manual). Selection of PDP structural BMPs for storm water pollutant control
must be based on the selection process described in Chapter 5. PDPs subject to
hydromodification management requirements must also implement structural BMPs for flow
control for hydromodification management (see Chapter 6 of the BMP Design Manual). Both
storm water pollutant control and flow control for hydromodification management can be
achieved within the same structural BMP(s).
PDP structural BMPs must be verified by the City at the completion of construction. This may
include requiring the project owner or project owner's representative to certify construction of
the structural BMPs (see Section 1.12 of the BMP Design Manual). PDP structural BMPs must
be maintained into perpetuity, and the City must confirm the maintenance (see Section 7 of the
BMP Design Manual).
Use this form to provide narrative description of the general strategy for structural BMP
implementation at the project site in the box below. Then complete the PDP structural BMP
summary information sheet for each structural BMP within the project (copy the BMP summary
information page as many times as needed to provide summary information for each individual
structural BMP).
Describe the general strategy for structural BMP implementation at the site. This information
must describe how the steps for selecting and designing storm water pollutant control BMPs
presented in Section 5.1 of the BMP Design Manual were followed, and the results (type of
BMPs selected). For projects requiring hydromodification flow control BMPs, indicate whether
pollutant control and flow control BMPs are integrated together or separate.
The Coastline Community Church project proposes to limit the amount of impervious area that will
be newly created or replaced, in order to reduce the footprint of the structural BMP. Biofiltration
basins will be utilized to provide both pollutant control and flow control. Harvest and reuse of storm
~ater is considered infeasible due to lack of indoor demand, and the infeasibility of modifying the
iexisting irrigation system to integrate storm water reuse.
Infiltration is partially feasible due to the low infiltration characteristics of Hydrologic Group D soils.
Therefore the most effective and feasible BMP for this site is a biofiltration basin (BF-1 }, which will
be shown as BMP-1, BMP-2, and BMP-3 on the plans. BMP-1 will be located at the northwest
K;orner of the site, and will have lined sides and an open bottom to allow for partial infiltration.
BMP-2 and BMP-3 are located near the center of the site, and the bottom and sides will be lined
~o prevent infiltration due to proximity to retaining walls.The BMPs have been sized using the BMP
Sizing Spreadsheet V2.0, and shall be used to meet both pollutant control and hydromodification
requirements.
Additionally, the site creates and/or replaces less than 50% of the existing impervious area,
therefore the BMP has been sized to treat only new and replaced impervious area. See Page 6 of
this report for quantified area.
16
[Continued from previous page -This page is reserved for continuation of description of general strategy for structural
BMP implementation at the site.]
BMP-1 Strategy:
8MP-1 has been sized to meet hydromodification and pollutant control requirements for the runoff
generated by the new project. 8MP-1 also treats the design capture volume (OCV) collected from a
portion of existing roof runoff (OMA-1 E), an existing 6" low-flow pipe (OMA-10). Via the existing 6" low-
flow pipe, 8MP-1 receives runoff from approximately 3.76 acres of the existing project and all areas
tributary to 8MP-2 and 8MP-3. The area tributary to the low-flow pipe is quantified as OMA-10 on the
OMA Exhibit, and the existing roof runoff tributary to 8MP-1 is quantified as OMA-1 E.
8MP-1 has been designed to store the hydromod volume generated by portions of the new project (OMA-
1 A, 18, and 1 C), as well as 75% of the OCV (per Option 2 of Section 8 .5 of Carlsbad 8MP Manual):
B.5 Biofiltration BMPs
Biofiltration BMPs shall be sizccl by one of the following s~ing methods:
Option 1: Treat 1.5 times the portion of the DCV not reliably retained onsite, OR
Option 2: Treat t .0 times the portion of the DCV not reliably retained onsite; and additionally check
that the systt>ffi has a tot1I static (i.e., non-routed) storage volume, including pore spaces and pre-filter
detention volume, equal to ar least 0.75 times the portion of the DCV not reliably retainc.-d on.site.
The required hydromod volume generated by the project for 8MP-1 is 2900 cubic feet, and the pollutant
control volume generated from the existing roof runoff and 6" low-flow pipe is 4433 cubic feet. Therefore,
the total required storage volume of 8MP-1 is 6,225 cubic feet (2900+ (0.75x4433)=6225 CF). The total
volume provided in 8MP-1 is 7,013 cubic feet. Volume calculations are tabulated in Appendix 1 e.
The OCV from the existing roof runoff and existing 6" low-flow pipe is calculated using the design capture
volume (OCV) equation in Appendix 8, Section 8 .1 of the 8MP Manual. Please see below, Attachment 1 a-
OMA Exhibit, and hydromod spreadsheets in Appendix 1e.
Per B.1 of Carlsbad BMP Manual
DCV=3630 x C x d x A
C=
d=
A=
0.56
0.58
3.76
C Factor Calculations:
Area tributary
sf
Impervious 93,600
Pervious 70,050
Total sf 163,650
Total Acres 3.76
Runoff factor per Section B.1.1
85th percentile, 24-hr storm depth (inches)
Tributary Area in Acres
C factor Weighted Area Weighted C
0.9 84,240
0.1 7,005 0.56
DCV= 3630x 0.56 X 0.58 3.76= 4433 cubic feet
Where ,
Area= OMA 10 + OMA 1 E= 3. 70 + 0.504= 3. 76 acres
Impervious Area= OMA 10 + OMA 1 E= 91,250 + 2,350= 93,600 sf
Pervious Area= OMA 10 + OMA 1 E= 70,050 + O= 70,050 sf
Please see Attachment 1 a-OMA Exhibit, for area breakdowns.
17
[Continued from previous page -This page is reserved for continuation of description of general strategy for structural
BMP implementation at the site.]
BMP-3 Strategy:
The impervious area of the garden chapel and stairs between the parking lot has been included
in the stormwater analysis. The location of the garden chapel (DMA-68) and stairs between the
parking lots (DMA-6A) make hydromodification and treatment difficult, and therefore an
equivalent amount of existing impervious area (DMA-3D, portion of existing parking lot) will be
diverted to BMP-3 for treatment. Please see the OMA Exhibit in Attachment 1 for further
information.
18
Structural BMP Summary Information
[Copy this page as needed to provide Information for each individual proposed
atr11rt■1ral BIIPl
Structural BMP ID No. BMP-1
DWG AMEND2018-0003 Sheet No. C2.0-C2.2
Type of structural BMP:
J Retention by harvest and use (HU-1)
J Retention by infiltration basin (INF-1)
J Retention by bioretention (INF-2)
J Retention by permeable pavement (INF-3)
X Partial retention by biofiltration with partial retention (PR-1)
Biofiltration (BF-1)
J Flow-thru treatment control included as pre-treatment/forebay for an onsite retention or
biofiltration BMP (provide BMP type/description and indicate which onsite retention or
biofiltration BMP it serves in discussion section below)
J Detention pond or vault for hydromodification management
J Other (describe in discussion section below)
Purpose:
J Pollutant control only
J Hydromodification control only
x Combined pollutant control and hydromodification control
J Pre-treatment/forebay for another structural BMP
J Other (describe in discussion section below)
Discussion (as needed):
18
Structural BMP Summary Information
[Copy this page as needed to provide Information for each individual proposed
structural BMP]
Structural BMP ID No. BMP-2
DWG AMEND2018-0003 Sheet No . C2.0-C2.2
Type of structural BMP:
J Retention by harvest and use (HU-1)
J Retention by infiltration basin (I NF-1 )
J Retention by bioretention (INF-2)
J Retention by permeable pavement (INF-3)
Partial retention by biofiltration with partial retention (PR-1)
X Biofiltration (BF-1)
J Flow-thru treatment control included as pre-treatment/forebay for an onsite retention or
biofiltration BMP (provide BMP type/description and indicate which onsite retention or
biofiltration BMP it serves in discussion section below)
J Detention pond or vault for hydromodification management
J Other (describe in discussion section below)
Purpose:
J Pollutant control only
J Hydromodification control only
x Combined pollutant control and hydromodification control
J Pre-treatment/forebay for another structural BMP
J Other (describe in discussion section below)
Discussion (as needed):
19
Structural BMP Summary Information
[Copy this page as needed to provide Information for each Individual proposed
idr11rt■■-1 BMPl
Structural BMP ID No. BMP-1
DWG AMEND2018-0003 Sheet No. C2.0-C2.2
Type of structural BMP:
J Retention by harvest and use (HU-1)
J Retention by infiltration basin (I NF-1)
J Retention by bioretention (INF-2)
J Retention by permeable pavement (INF-3)
X Partial retention by biofiltration with partial retention (PR-1)
Biofiltration (BF-1)
J Flow-thru treatment control included as pre-treatment/forebay for an onsite retention or
biofiltration BMP (provide BMP type/description and indicate which onsite retention or
biofiltration BMP it serves in discussion section below)
J Detention pond or vault for hydromodification management
J Other (describe in discussion section below)
Purpose:
J Pollutant control only
J Hydromodification control only
x Combined pollutant control and hydromodification control
J Pre-treatment/forebay for another structural BMP
J Other (describe in discussion section below)
Discussion (as needed):
20
ATTACHMENT 1
BACKUP FOR PDP POLLUTANT CONTROL BMPS
This is the cover sheet for Attachment 1 .
Check which Items are Included behind this cover sheet:
Attachment Contents Checklist
Sequence
Attachment 1 a OMA Exhibit (Required) 181 Included
See OMA Exhibit Checklist on the back !Also Included:
of this Attachment cover sheet. • Existing Impervious Area Exhibit
(24"x36" Exhibit typically required)
Attachment 1 b Tabular Summary of DMAs Showing 181 Included on OMA Exhibit in
OMA ID matching OMA Exhibit, OMA !Attachment 1 a
Attachment 1 c
Attachment 1 d
Area, and OMA Type (Required)* J Included as Attachment 1 b,
*Provide table in this Attachment OR
on OMA Exhibit in Attachment 1 a
Form 1-7, Harvest and Use Feasibility
Screening Checklist (Required unless
the entire project will use infiltration
8MPs)
Refer to Appendix 8 .3-1 of the 8MP
Design Manual to complete Form 1-7.
Form 1-8, Categorization of Infiltration
Feasibility Condition (Required unless
the project will use harvest and use
8MPs)
Refer to Appendices C and D of the
8MP Design Manual to complete Form
1-8.
separate from OMA Exhibit
181 Included
J Not included because the entire project
will use infiltration 8MPs
181 Included
J Not included because the entire project
will use harvest and use 8MPs
Attachment 1e Pollutant Control BMP Design 181 Included:
Worksheets / Calculations (Required)
Refer to Appendices B and E of the
8MP Design Manual for structural
pollutant control 8MP design
guidelines
21
• Worksheet 8.5-1 : 8MP Sizing Worksheet
• Worksheet 8 .5-3: County Alternate Minimum
8iofiltration Footprint Ratio
• San Diego County Rainfall 30 Year Annual
Average Map
• 8MP Sizing Spreadsheet V2.0 for
Hydromod Sizing
• 8MP-1 Volume Size Verification
• 8MP Drawdown Calculations
Use this checklist to ensure the required information has been included on the OMA
Exhibit:
The OMA Exhibit must identify:
J ~ Underlying hydrologic soil group
J ~ Approximate depth to groundwater
J ~ Existing natural hydrologic features (watercourses, seeps, springs, wetlands)
J ~ Critical coarse sediment yield areas to be protected (if present)
J ~ Existing topography and impervious areas
J ~ Existing and proposed site drainage network and connections to drainage offsite
J ~ Proposed grading
J ~ Proposed impervious features
J ~ Proposed design features and surface treatments used to minimize imperviousness
J ~ Drainage management area (OMA) boundaries, OMA ID numbers, and OMA areas
(square footage or acreage), and OMA type (i.e., drains to BMP, self-retaining, orself-
mitigating)
~ Structural BMPs (identify location and type of BMP)
22
Appendix B: Storm Water Pollutant Control Hydrologic Calculat ions and Sizing Methods
Worksheet B.5-1 Simple Sizing Method for Biofiltration BMPs
L,r,-,1,u~ 111 : -• •J••TtJIK • :·•;1u . :i.•,1!.I.., ~
Tributary area 5.17
Adjusted runoff factor for drainage area 0.58
85th percentile, 24-hr storm even rainfall depth 0.58
1 Remaining DCV after lmplementlong retention BMPs 1 6,317
Partial Retention
2 Infiltration rate if partial infiltration is feasible 0.024
3 Allowable drawdown time for auregate stoarage below the undredrain 36
4 Death of runoff that can be infiltrated (Line 2 x Line 3) 0.864
5 Aareaate pore soace 0.40
6 Required depth of gravel below the underdrain (Line 4 x Line SJ 2
7 Assumed surface area of the biofiltration BMP 2,875
8 Media retained pore soace 0.1
9 Volume retained by BMP [[Une 4 + (Line 12 x Line 8)V12l x Line 7 638.25
10 DCV that reauires bloflltration [Line 1-Line 9) 5,679
BMP Parameters
11 Surface Ponding (6"-12") 24
12 Media Thickness (18" min) Add mulch layer thickness 18
13 Aggregate Storage above underdrain invert (12" typ) 27
14 Freelv drained pore storage 0.2
15 Media filtration rate to be used for sizing 0.17
Baseline Calculations
16 Allowable Routing Time for sizina 6
17 Depth filtered during storm (Line 15 x Line 16] 1.02
18 Depth of Detention Storaae [Une 11 + (Une 12 x Une 14) + (Une 13 x Une 5)1 38.40
19 Total Depth Treated [Line 17 + Line 18) 39.42
Option 1 -Biofilter 1.5 times the DCV
20 Required bloflltered volume (1.5 x Line 10) 8,518
21 Required Footprint [Line 20/ Line 19) x 12 2,593
Option 2 -Store 0.75 of remaining DCV in pores and ponding
22 Reauired Stora1e (surface+ DOres) Volume (0.7S x Line 10)
23 Reauired Footprint [Line 22/ Line 18) x 12
Footprint of the BMP
24 Area draining to the BMP
25 Adjusted Runoff Factor for draina11e area
BMI" Footprtnt Sizing Factor 1uerau1t o.o3 or an a1temat1ve minimum TOOtpr1nt
26 sizing factor from County Worksheet 8.5-3, Line 22) 2
27 Minimum BMP Footprint [Line 24x Line 25 x Line 26)
28 Footprint of the BMP= Maxium (Minimum(Une 21, 23), Line 27)
1 DCV Calculated per Appendix B, Section B.1 of Carlsbad BMP Manual:
DCV=3630 x C x d x A, where:
C= _ (Runoff factor per Section B.1.1. Pleose see OMA Exhibit in
Attachment la for C calculations)
d= 0.58 (85th Percentile, 24-hr storm depth in inches)
A= (Tributary Area in Acres)
4,259
1,331
225,337
0.58
0.022
2,875
2,875
~
0.10
0.8
0.58
168
-
36
-
0.40
-
240
0.1
36.00
132
12
18
15
0.2
0.01
6
0.08
21.60
21.68
199
110
99
55
4,356
0.80
0.03
105
105
I~ l!filI1.l
0.50 acres
0.75
0.58 inches
790 cubic-feet
-in/hr.
36 hours
-inches
0.40 in/In
-inches
915 sq-ft
0.1 in/in
137.25 cubic-feet
652 cubic-feet
12 inches
18 inches
15 inches
0.2 In/In
0.06 in/hr.
6 hours
0.37 inches
21.60 inches
21.97 inches
978 cubic-feet
535 sq-ft
489 cubic-feet
272 SQ-ft
21,780 SQ-ft
0.75
0.03
490 SQ-ft
490 sq-ft
2BMP-1 has been sized with an alternative minimum footprint sizing factor. Please see Worksheet B.5-3 in SWQMP Attachment l e for
supporting calculations.
Page 1 of 1
Appendix H: Guidance for Investigation Potential Critical Coarse Sediment Yield Areas
Harvest and Use Feasibility Checklist Form 1-7
1. Is there a demand for harvested water (check all that apply) at the project site that is reliably present
during the wet season? Harvest and reuse is infeasible due to lack of indoor demand
D Toilet and ~r~al flushing and the infeasibility of modifying the existing irrigation syst~m
D Landscape u-ngation to integrate storm water reuse.
~ Other:
2. If there is a demand; estimate the anticipated average wet season demand over a period of 36 hours.
Guidance for planning level demand calculations for toilet/urinal flushing and landscape irrigation is
provided in Section B.3.2.
[Provide a swnmary of calculations here]
3. Calculate the D CV using worksheet B-2.1.
D CV = ( cubic feet)
3a. Is the 36 hour demand greater
than or egual to the DCV?
D Yes / □No ~
-0,
Harvest and use appears to be
feasible. Conduct more detailed
evaluation and sizing calculations
to confu-m that D CV can be used
at an adequate rate to meet
clrawdown criteria.
36. Is the 36 hour demand greater than 0.25DCV
but less than the full DCV?
D Yes / D No
.0.
Harvest and use may be feasible. Conduct more
detailed evaluation and sizing calculations to
determine feasibility. Harvest and use may only be
able to be used for a portion of the site, or
(optionally) the storage may need to be upsized to
meet long term capture targets while draining in
longer than 36 hours.
Is harvest and use feasible based on further evaluation?
D Yes, refer to Appendix E to select and size harvest and use BMPs.
Xl No, select alternate BMPs.
Storm Water Standards
Part 1: BMP Design Manual
January 2016 Edition I-3
3c. Is the 36
hour demand
less than
0.25DCV?
D Yes n
Harvest and
use 1s
considered to
be in feasible.
FORM FOR BMP-1
Appendix I: Forms and Checklists
C . . f I fil . F .b.li C d. . Form 1-8 ategor1zauon o n 1 trauon east 1 ty on 1t10n
Part 1 -Full Infiltration Feasibility Screening Criteria
Would infiltration of the full design volume be feasible from a physical perspective without any undesirable
consequences that cannot be reasonably mitigated?
Criteria Screening Question Yes No
Is the estimated reliable infiltration rate below proposed facility
locations greater than 0.5 inches per hour? The response to this
Screening Question must be based on a comprehensive evaluation of
the factors presented in Appendix C.2 and Appendix D.
X
Provide basis:
The site consists of site class D soils, which have low infiltration rates. A
reliable infiltration rate greater than 0.5 inches per hour is not feasible.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/ data source applicability.
2
Can infiltration greater than 0.5 inches per hour be allowed
without increasing risk of geotechnical hazards (slope stability,
groundwater mounding, utilities, or other factors) that cannot be
mitigated to an acceptable level? The response to this Screening
Q uestion must be based on a comprehensive evaluation of the fac tors
presented in Appendi..x C.2.
X
Provide basis:
BMP-1 is located at the northwest corner of the site, and although slope
stability and ground water mounding are not areas of concern, the infiltration
rate is less than 0.5 inches per hour.
Swnmarize fi11dings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of sn1dy/data source applicability.
1-3 February 26, 2016
Appendix I: Forms and Checklists
,. ,· Form 1-8 Page 2 of4 . .
Criteria
3
Screening Question
Can infiltration greater than 0.5 inches per hour be allowed
without increasing risk of groundwater contamination (shallow
water table, storm water pollutants or other factors) that cannot
be mitigated to an acceptable level? The response to this Screening
Question must be based on a comprehensive evaluation of the factors
presented in Appendix C.3.
Provide basis:
There is no anticipated risk of groundwater contamination.
Yes No
X
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/ data source applicability.
4
Can infiltration greater than 0.5 inches per how be allowed
without causing potential water balance issues such as change of
seasonality of ephemeral streams or increased discharge of
contaminated groundwater to surface waters? The response to this
Screening Question must be based on a comprehensive evaluation of
the factors presented in Appendix C.3.
Provide basis:
There is no anticipated risk of water balance issues.
X
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/ data source applicability.
Part 1
Result
*
If all answers to rows 1 -4 are "Yes" a full infiltration design is potentially feasible. The
feasibility screening category is Full Infiltration
If any answer from row 1-4 is "No", infiltration may be possible to some extent but
would not generally be feasible or desirable to achieve a "full infiltration" design.
Proceed to Part 2
No
"To be completed using gathered site information and best professional judgment considering the definition of MEP in
the lvfS4 Permit. Additional testing and/or studies may be required by Agency/Jurisdictions to substantiate findings
1-4 February 26, 2016
Appendix I: Forms and Checklists
1
l,c Form 1,-8 Page 3 of 4
P art 2 -Partial Infiltration vs. No Infiltration Feasibility Screening Criteria
Would infiltration of water in any appreciable amount be physically feasible without any negative
consequences that cannot be reasonably mitigated?
Criteria Screening Question Yes No
5
Do soil and geologic conditions allow for infiltration in any
appreciable rate or volume? The response to this Screening
Question must be based on a comprehensive evaluation of the factors
presented in Appendix C.2 and Appendix D.
X
Provide basis:
The site is classified as Site Class D soils, and has a very slow infiltration rate.
Per the Geotech Report, partial infiltration is allowable for BMP-1 .
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/ data source applicability and why it was not fe asible to mitigate low infiltration rates.
6
Can Infiltration in any appreciable quantity be allowed without
increasing risk of geotechnical hazards (slope stability,
groundwater mounding, utilities, or other factors) that cannot
be mitigated to an acceptable level? The response to this Screening
Question must be based on a comprehensive evaluation of the factors
presented in Appendix C.2.
X
Provide basis:
The site is classified as Site Class D soils, and has a very slow infiltration rate.
Per the Geotech Report, partial infiltration is allowable for BMP-1. At the
location of BMP-1 , slope stability and groundwater mounting are not areas of
concern.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/ data source applicability and why it was not feasible to mitigate low infiltration rates.
1-5 February 26, 2016
Appendix I: Forms and Checklists
. '
Criteria
7
Form. 1-8 Page ~:·of 4
Screening Question
Can Infiltration in any appreciable quantity be allowed without
posing significant risk for groundwater related concerns
(shallow water table, storm water pollutants or other factors)?
The response to th.is Screening Question must be based on a
comprehensive evaluation of the factors presented in Appencli.x C.3.
Provide basis:
Yes
X
For BMP-1, infiltration can be allowed without posing significant risk
groundwater related concerns.
No
Summarize findings o f studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/data source applicability and why it was not feasible to mitigate low infiltration rates.
8
Can infiltration be allowed without violating downstream water
rights? The response to this Screening Question must be based on a
comprehensive evaluation of the factors presented in Appendix C.3. X
Provide basis:
For BMP-1, infiltration can be allowed without violating downstream water
rights.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/data source applicability and why it was not feasible to mitigate low infiltration rates.
Part 2
Result*
If all answers from row 1-4 are yes then partial infiltration design is potentially feasible.
The feasibility screening category is Partial Infiltration.
If any answer from row 5-8 is no, then infiltration of any volume is considered to be
infeasible within the drainage area. The feasibility screening category is No Infiltration.
Partial
Infiltration
#To be completed using gathered site information and best professional judgment considering the definition of t.1EP in
the MS4 Permit. Additional testing and/or studies may be required by ,-\gency/J urisdictions to substantiate findings
1-6 February 26, 2016
FORM FOR BMP-2 and BMP-3 Appendix I: Forms and Checklists
-
C . . f I fil . F .b.li C d... Form 1-8 ategorizatton o n 1 tratton east 1 ty on 1t10n
Part 1 -Full Infiltration Feasibility Screening Criteria
Would infiltration of the full design volume be feasible from a physical perspective without any undesirable
consequences that cannot be reasonably mitigated?
Criteria Screening Question
Is the estimated reliable infiltration rate below proposed facility
locations greater than 0.5 inches per hour? The response to this
Screening Q uestion must be based on a comprehensive evaluation of
the factors presented in Appendix C.2 and Appendix D.
Yes No
X
Provide basis:
The site consists of site class D soils, which have low infiltration rates. A
reliable infiltration rate greater than 0.5 inches per hour is not feasible.
Summarize findings of studies; provide reference to sn1dies, calculations, maps, data sources, etc. Provide narrative
discussion o f snidy / data source applicability.
2
Can infiltration greater than 0.5 inches per hour be allowed
without increasing risk of geotechnical hazards (slope stability,
groundwater mounding, utilities, or other factors) that cannot be
mitigated to an acceptable level? The response to this Screening
Question must be based on a comprehensive evaluation of the factors
presented in Appendix C.2.
X
Provide basis:
The infiltration rate is less than 0.5 inches per hour, and BMP-2 and BMP-3
are located in areas of fill. Per the geotechnical report, adequate site drainage
is required to reduce the potential for differential soil movement, erosion, and
subsurface seepage.
Summarize findings of studies; provide reference to snidies, calculations, maps, data sources, etc. Provide narrative
discussion of snidy / data source applicability.
1-3 February 26, 2016
Appendix I: Forms and Checklists
' ~ Form 1-8 Page 2 of 4
Criteria
3
Screening Question
Can infiltration greater than 0.5 inches per hour be allowed
without increasing risk of groundwater contamination (shallow
water table, storm water pollutants or other factors) that cannot
be mitigated to an acceptable level? 111e response to this Screening
Question must be based on a comprehensive evaluation of the factors
presented in Appendix C.3.
Provide basis:
There is no anticipated risk of groundwater contamination.
Yes No
X
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/ data source applicability.
4
Can infiltration greater than 0.5 inches per hour be allowed
without causing potential water balance issues such as change of
seasonality of ephemeral streams or increased discharge of
contaminated groundwater to surface waters? The response to th.is
Screening Question must be based on a comprehensive evaluation of
the factors presented in Appendix C.3.
Provide basis:
There is no anticipated risk of water balance issues.
X
Swnmarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/ data source applicability.
Part 1
Result
*
If all answers to rows 1 -4 are "Yes" a full infiltration design is potentially feasible. The
feasibility screening category is Full Infiltration
If any answer from row 1-4 is "No", infiltration may be possible to some extent but
would not generally be feasible or desirable to achieve a "full infiltration" design.
Proceed to Part 2
No
.-To be completed usillg gathered site information and best professional judgment considering the definition of l\IEP in
the l\IS4 Permit. Additional testing and/or sn1dies may be required by .-\gency/Jurisdictions ro substantiate filldings
1-4 February 26, 2016
Appendix I : Forms and Checklists
J'"l r Form 1-8 Page 3 of 4
Part 2 -Partial Infiltration vs. No Infiltration Feasibility Screening Criteria
Would infiltration of water in any appreciable amount be physically feasible without any negative
consequences that cannot be reasonably mitigated? ..
Criteria
5
Screening Question
Do soil and geologic conditions allow for infiltration in any
appreciable rate or volume? The response to this Screening
Question must be based on a comprehensive evaluation of the factors
presented in Appendix C.2 and Appendix D .
Yes No
X
Provide basis:
The site is classified as Site Class D soils, and has a very slow infiltration rate.
The infiltration rate is less than 0.5 inches per hour, and BMP-2 and BMP-3
are located in areas of fill. Per the geotechnical report, adequate site drainage
is required to reduce the potential for differential soil movement, erosion, and
subsurface seepage.
Summarize findings of snidies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/ data source applicability and why it was not feasible to mitigate low infiltration rates.
6
Can Infiltration in any appreciable quantity be allowed without
increasing risk of geotechnical hazards (slope stability,
groundwater mounding, utilities, or other factors) that cannot
be mitigated to an acceptable level? The response to this Screening
Question must be based on a comprehensive evaluation of the factors
presented in Appendix C.2.
X
Provide basis:
BMP-2 and BMP-3 are located in areas of previous fill , and they will be located
adjacent to parking lot and retaining walls. Per the geotechnical report,
adequate site drainage is required to reduce the potential for differential soil
movement, erosion, and subsurface seepage. The geotechnical report also
states that under no circumstances should water be allowed to pond adjacent
to footings.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/ data source applicability and why it was not feasible to mitigate low infiltration rates.
1-5 February 26, 2016
Appendix I: Forms and Checklists
I • ,_. : .--: • ,--,.; ••~-• •
Fo_rn:i I-~ Page~ of 4
Criteria Screening Question Yes No
7
Can Infiltration in any appreciable quantity be allowed without
posing significant risk for groundwater related concerns
(shallow water table, storm water pollutants or other factors)?
The response to this Screening Question must be based on a
comprehensive evaluation of the factors presented in Appendix C.3.
X
Provide basis:
Infiltration can be allowed without posing significant risk groundwater related
concerns, however infiltration is not allowed due to soil movement and erosion
concerns.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of sn1dy / data source applicability and why it was not fea sible to mitigate low infiltration rates.
8
Can infiltration be allowed without violating downstream water
rights? The response to this Screening Question must be based on a
comprehensive evaluation of the factors presented in Appendix C.3. X
Provide basis:
Infiltration can be allowed without violating downstream water rights, however
infiltration is not allowed due to soil movement and erosion concerns.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/ data source applicability and why it was not feasible to mitigate low infiltration rates.
Part 2
Result*
If all answers from row 1-4 are yes then partial infiltration design is potentiall)' feasible.
The feasibility screening category is Partial Infiltration.
If any answer from row 5-8 is no, then infiltration of any volume is considered to be
infeasible within the drainage area. The feasibility screening category is No Infiltration.
No
Infiltration
:r--ro be completed usmg gathered site information and best professional Judgment cons1denng the definition of NfEP u1
the .l'v1S4 Permit. Additional testing and/ or studies may be required by Agency /Jurisdictions to substantiate findings
1-6 February 26, 2016
0
Category
Drainage Basin
Info
Biofiltration
Clogging
Inputs
Minimum
Footprint
Calculations
# -
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
Worksheet B.5-3 General Notes:
Automated Worksheet B.5-3: Alternate Minimum Biofiltration Foot
mm P1l ,m m
Drainage Basin ID or Name I BMP-1
Drains to following BMP Type Bio filtration ---
Final Effective Tributary _-\rea 130,698 ---
Is Proposed Biofiltration BMP <3% of Effective Tributary .-\rea Desired? Yes No No No
.-\ verage _-\nnual Precipitation 12.7
Load to Clog (default =2.0) 3.0
.-\llowable Period to .-\ccumulate Clogging Load (default =10) 10
Pretreatment Measures Included? No
Commercial: TSS=128 mg/L, C= 0.80
Education: TSS=132 mg/L, C= 0.50 107,869
Industrial: TSS=125 mg/L, C= 0.90
Low Traffic .-\reas: TSS=S0 mg/L, C= 0.50
Multi-Family Residential: TSS=40 mg/L, C= 0.60
Roof ,-\reas: TSS=14 mg/L, C= 0.90 22,829
Single Family Residential: TSS=123 mg/L, C= 0.40
Transportation: TSS=78 mg/L, C= 0.90
Vacant/Open Space: TSS=216 mg/L, C= 0.10
Effective-.-\rea Based on Specified Land Use Coefficients 74,480 0 0 0
.-\verage TSS Concentration for Tributary 99 0 0 0
.-\ verage .-\nnual Runoff 138,322 0 0 0
,-\verage .-\nnual TSS Load 855 0 0 0
.-\verage .-\nnual TSS Load ,-\fter Pretreatment Measures 855 0 0 0
J\finimum .-\llowable Biofiltration Footprint Ratio 0.022 ---
onnt R atrn
V Ill l11ll Vlll ,n X Units
------unitless
------sq-ft
No No No No No No yes/no
inches
lb/sq-ft
years
yes/no
sq-ft
sq-ft
sq-ft
sq-ft
sq-ft
sq-ft
sq-ft
sq-ft
sq-ft
0 0 0 0 0 0 sq-ft
0 0 0 0 0 0 mg/L
0 0 0 0 0 0 cubic-feet
0 0 0 0 0 0 lb/yr
0 0 0 0 0 0 lb/yr
------ratio
.-\ .. -\pplicants may use this worksheet to calculate .-\lternate J\finimum Biofiltration Footprint Ratios for up to 10 basins. User input must be provided for yellow shaded cells, values for blue cells are automatically populated based on user inputs from previous worksheets, values
for all other cells will be automatically generated, errors/notifications will be highlighted in red and summarized below. Inputs for Lines 4-7 (precipitation, load to clog, clogging period, and pretreatment measures) must be supported through supplemental documentation.
DISCUSSION:
Alternative sizing is based on combined total of DMA-1A (portion of new project) and DMA-1 D (existing area tributary to 6" low-flow pipe). Line 2, "Final Effective Tributary Area" is
calculated by AX C, where A is total area tributary to BMP (225,342 sf) and C is the weighted C Factor (0.58). Therefore AxC= 225,342 X 0.58 = 130,698 sf. See OMA Exhibit for
Area and C factor calculations.
Average Annual Precipitation data obtained from San Diego County Flood Control Website; "San Diego County Rainfall-30 year Annual Average Map" pdf:
https://www.sandiegocounty.gov/content/dam/sdc/dpw/FLOOD_CONTR0Ufloodcontroldocuments/Average%20Annual%20Rainfall.pdf
BMP-1 will have a vegetated cover of at least 75%, generating a "Load to Clog" Factor of 3. (Per Table B.5-3 of 2016 County BMP Manual)
Roof Runoff based on approximately 25,365 sf of roof area over existing and proposed project site. (25 ,365 sf * 0.9 c factor= 22,829 sf)
BMP Sizing Spreadsheet V2.0
Project Name: Coastline Community Church
Project Applicant:
Jurisdiction: City of Carlsbad
Parcel (APN}: 255-273-07-00
Hydrologic Unit: Carlsbad
Rain Gauge: Oceanside
Total Project Area (sf):
Channel Susceptibility: Low
BMP Sizing Spreadsheet V2.0
Project Name: Coastline Community Church Hydrologic Unit: Carlsbad
Project Applicant: Rain Gauge: oceanside
Jurisdiction: City of carlsbad Total Project Area:
Parcel (APN): 255-273-07-00 Low Flow Threshold: 0.502
BMP Name: BMP-1 BMPType: 8iofiltrat1on w/ Partial Retention & Biofiltration w/o Impermeable Liner
BMP Native Soil Type: 0 BMP Infiltration Rate (in/hr): 0.024
Areas Draining to BMP HMP Sizing Factors Minimum BMP Size
OMA Post Project Runoff Factor Bioretention Bioretention Surface Volume
Name Area (sf) Soil Type Pre-project Slope Surface Type (Table G.2-1)' Surface Area Surface Volume Subsurface Volume Surface Area (sf) (cf) N/A
OMA-lA (Impervious) 37,012 0 Steep Impervious 1.0 0.05 0.0417 0.03 1851 1543 1110
OMA-lA (Landscape) 4,463 D Steep Pervious 0.1 0.05 0.0417 0.03 22 19 13
DMA-1B (Playground) 10,575 D Steep PervKlus 0.1 0.05 0.0417 0.03 53 44 32
OMA-lC (Pavers) 9,642 D Steep Perv1ous (Perm. Pave) 0.2 0.05 0.0417 0.03 96 80 58
Total BMP Area 61,692 Minimum BMP Size 2022.21 1687 1213
Proposed BMP Size• 2080 4160 1248
Soil Matrix Depth 18.00 in
Minimum Ponding Depth 9.73 in
Maximum Ponding Depth 324.66 in
Selected Ponding Depth 24.00 in
Notes:
1. Runoff factors which are used for hydromodification management flow control (Table G.2-1) are different from the runoff factors used for pollutant control BMP sizing (Table 8.1-1). Table references are taken from the san Diego Region Model BMP Design Mani
Describe the BMP's in sufficient detail in your POP SWQMP to demonstrate the area, volume, and other criteria can be met within the constraints of the site.
BM P's must be adapted and applied to the conditions specific to the development project such as unstable slopes or the lack of available head.
Designated Staff have final review and approval authority over the project design.
This BMP Sizing Spreadsheet has been updated in conformance with the San Diego Region Model BMP Design Manual, February 2016. For questions or concerns please contact the jurisdiction in which your project is located.
BMP Sizing Spreadsheet V2.0
Project Name: astline Community Chu, Hydrologic Unit: Carlsbad
Project Applicant: Rain Gauge: Oceanside
Jurisdiction: City of Carlsbad Total Project Area:
Parcel (APN): 255-273-07-00 Low Flow Threshold: 0.5Q2
BMP Name BMP-1 BMPType: Biofiltration w/ Partial Retention & Biofiltration w/o Impermeable Liner
OMA Rain Gauge Pre-developed Condition Q2 Sizing Factor OMA Area (ac) Orifice Flow -%Q2 Orifice Area
Name Soil Type Cover Slope (cfs/ac) (cfs) (in2)
DMA-lA (Impervious) Oceanside D Scrub Steep 0.244 0.850 0.104 2.53
DMA-lA (Landscape) Oceanside D Scrub Steep 0.244 0.102 0.012 0.31
DMA-18 (Playground) Oceanside D Scrub Steep 0.244 0.243 0.030 0.72
DMA-lC (Pavers) Oceanside D Scrub Steep 0.244 0.221 0.027 0.66
Scrub
Scrub
Scrub
Scrub
Scrub
Scrub
Scrub
Scrub
Scrub
Scrub
Scrub
0.173 4.22 2.32
Tot. Allowable Tot. Allowable Max Orifice
Orifice Flow Orifice Area Diameter
(cfs) (in2) (in)
0.163 3.98 2.25
Actual Orifice Flow Actual Orifice Area Selected
Orifice Diameter
(cfs) (in2) (in)
Drawdown (Hrs) 7.1
BMP Sizing Spreadsheet V2.0
Project Name: Coastline Community Church Hydrologic Unit: Carlsbad
Proiect Applicant: Rain Gauge: Oceanside
Jurisdiction: City of Carlsbad Total Project Area:
Parcel (APN): 255-273-07-00 low Flow Threshold: 0.5Q2
BMP Name: BMP-2 BMPType, Biofiltration w/ Impermeable liner
BMP Native Soil Type: D BMP Infiltration Rate (in/hr): 0.024
Areas Draining to BMP HMP Sizing Factors Minimum BMP Size
DMA Post Project Runoff Factor Surface Volume Subsurface Volume
Name Area (sf) Soil Type Pre·project Slope Surface Type (Table G.2-1)1 Surface Area Surface Volume Subsurface Volume Surface Area (sf) (cf) (cf)
DMA-2 (Parking Lot) 3,976 D Steep Impervious 1.0 0.05 0.0417 0.03 199 166 119
OMA-2 (Basin) 240 0 Steep lmperv10us 0.1 0.05 0.0417 0.03 1 I 1
DMA-2 (Landscape) 354 0 Steep Pervious 0.1 0.05 0.0417 0.03 2 I 1
Total SMP Area 4,570 Minimum BMP Size 201.77 168 121
Proposed BMP Size• 240 240 144
Soil Matrix Depth 18.00 in
Minimum Ponding Depth 8.41 in
Maximum Ponding Depth 138.95 in
Selected Ponding Depth 12.00 in
Notes:
1. Runoff factors which are used for hydromodlficatK>n management flow control (Table G.2·1) are different from the runoff factors used for pollutant control BMP sizing (Table 8.1-1). Table references are taken from the San Diego Region Model BMP Design Mant
Describe the BMP's in sufficient detail in your POP SWQMP to demonstrate the area, volume, and other criteria can be met w ithin the constraints of the site.
BM P's must be adapted and applied to the conditions specific to the development project such as unstable slopes or the lack of available head.
Designated Staff have final review and approval authority over the project design.
This SMP Sizing Spreadsheet has been updated in conformance with the San Diego Region Model BMP Design Manual, February 2016. For questions or concerns please contact the jurisdiction in which your project is located.
BMP Sizing Spreadsheet V2.0
Project Name: astline Community Chu Hydrologic Unit: Carlsbad
Project Applicant: Rain Gauge: Oceanside
Jurisdiction: City of Carlsbad Total Project Area:
Parcel {APN): 255-273-07-00 Low Flow Threshold: 0.5Q2
BMP Name BMP-2 BMPType: Biofiltration w/ Impermeable Liner
OMA Rain Gauge Pre-developed Condition Q2 Sizing Factor OMA Area (ac) Orifice Flow -%Q2 Orifice Area
Name Soil Type Cover Slope (cfs/ac) (cfs) (in2)
OMA-2 (Parking Lot) Oceanside 0 Scrub Steep 0.244 0.091 0.011 0.27
OMA-2 (Basin) Oceanside 0 Scrub Steep 0.244 0.006 0.001 0.02
OMA-2 (Landscape) Oceanside 0 Scrub Steep 0.244 0.008 0.001 0.02
Scrub
Scrub
Scrub
Scrub
Scrub
Scrub
Scrub
Scrub
Scrub
Scrub
Scrub
Scrub
0.013 0.31 0.63
Tot. Allowable Tot. Allowable Max Orifice
Orifice Flow Orifice Area Diameter
(ds) (in2) (in)
0.008 0.20 0.50
Actual Orifice Flow Actual Orifice Area Selected
Orifice Diameter
(cfs) (in2) (in)
Orawdown (Hrs) 8.3
BMP Sizing Spreadsheet V2.0
Project Name: Coastline Community Church Hydrologic Unit: Carlsbad
Project Applicant: Rain Gauge: Oceanside
Jurisdiction: City of Carlsbad Total Project Area:
Parcel (APN): 255-273-07-00 Low Flow Threshold: 0.5Q2
BMPName: BMP-3 BMPType: Biofittration w/ Impermeable Liner
BMP Native Soil Type: D BMP Infiltration Rate (in/hr): 0.024
Areas Draining to BMP HMP Sizing Factors Minimum BMP Size
OMA Post Project Runoff Factor Surface Volume Subsurface Volume
Name Area (sf) Soil Type Pre-project Slope Surface Type (Table G.2-1)' Surface Area Surface Volume Subsurface Volume Surface Area (sf) (cf) (cf)
DMA·3A (Parking) 10,955 D Steep Impervious 1.0 0.05 0.D417 0.03 548 457 329
DMA-3A (Basin) 915 D Steep Pervious 0.1 0.05 O.D417 0.03 5 4 3
DMA-3A {Landscape) 2,823 D Steep Perv10us 0.1 0.05 O.D417 0.03 14 12 8
DMA-3B {Parking) 3,002 D Steep Impervious 1.0 0.05 O.D417 0.03 150 125 90
DMA-3B (Walkway) 1,589 D Steep Impervious 1.0 0.05 O.D417 0.03 79 66 48
DMA-3B (Landscape) 470 D Steep Pervtous 0.1 0.05 O.D417 0.03 2 2 1
DMA-3C (Building) 1,247 D Steep lmpervK>us 1,0 0.05 O.D417 0.03 62 52 37
DMA-3D (Ex1Sting Area) 790 D Steep Existing Impervious 1.0 0.05 O.D417 0.03 40 33 24
Total BMP Area 21,791 Minimum BMP Size 900.19 751 540
Proposed BMP Size• 915 915 549
Soil Matrix Depth 18.00 in
Minimum Ponding Depth 9.85 in
Maximum Ponding Depth 209.92 in
Selected Ponding Depth 12.00 in
Notes:
1. Runoff factors which are used for hydromodification management flow control {Table G.2-1} are different from the runoff factors used for pollutant control BMP sizing (Table B.1-1). Table references are taken from the san Diego Region Model BMP Design Mam
Describe the BM P's in sufficient detail in your PDP SWQMP to demonstrate the area, volume, and other criteria can be met within the constraints of the site.
BM P's must be adapted and applied to the conditions specific to the development project such as unstable slopes or the lack of available head.
Designated Staff have final review and approval authority over the project design.
This BMP Sizing Spreadsheet has been updated in conformance with the San Diego Region Model BMP Design Manual, February 2016. For questions or concerns please contact the jurisdiction in which your project is located.
BMP Sizing Spreadsheet V2.0
Project Name: astline Community Chu, Hydrologic Unit: Carlsbad
Project Applicant: Rain Gauge: Oceanside
Jurisdiction: City of Carlsbad Total Project Area:
Parcel {APN): 255-273-07-00 Low Flow Threshold: 0.502
BMP Name BMP-3 BMPType: Biofiltration w/ Impermeable Liner
OMA Rain Gauge Pre-developed Condition 0 2 Sizing Factor OMA Area (ac) Orifice Flow -%02 Orifice Area
Name Soil Type Cover Slope (cfs/ac) (ds) (in2)
DMA-3A {Parking) Oceanside D Scrub Steep 0.244 0.251 0.031 0.75
DMA-3A (Basin) Oceanside D Scrub Steep 0.244 0.021 0.003 0.06
DMA-3A (Landscape) Oceanside D Scrub Steep 0.244 0.065 0.008 0.19
Scrub
DMA-38 (Parking) Oceanside D Scrub Steep 0.244 0.069 0.008 0.21
DMA-3B {Walkway) Oceanside D Scrub Steep 0.244 0.036 0.004 0.11
DMA-38 (Landscape) Oceanside D Scrub Steep 0.244 0.011 0.001 0.03
Scrub
Scrub
DMA-3C (Building) Oceanside D Scrub Steep 0.244 0.029 0.003 0.09
Scrub
DMA-3D (Existing Area) Oceanside D Scrub Steep 0.244 0.018 0.002 0.05
Scrub
Scrub
Scrub
0.061 1.49 1.38
Tot. Allowable Tot. Allowable Max Orifice
Orifice Flow Orifice Area Diameter
{ds) (in2) (in)
0.046 1.13 1.20
Actual Orifice Flow Actual Orifice Area Selected
Orifice Diameter
(ds) (in2) (in)
Drawdown (Hrs) 5.5
BASIN VOLUME CALCULATIONS
Depth (D) Slope Base (B) Ll Bottom AsMP 2 D adj3 D adj Voids
BMP-1
(D x Slope) (ft) (ft2) ft (in)
water ponding 2 3 6 170 1740 2.586207 31.0 l
soil 1.5 l 1.5 170 1740 1.609914 19.3 0.2
pea qravel + qravel 2.5 l 2.5 170 1740 2.805316 33.7 0.4
Total Provided
Volume Required : cf
DMA-1 A/1 B/1 C 2900 (Hydromod)
DMA-l D and OMA-l E 3324.75 (75% of DCV)
Total Req'd 6224.75
NOTE:
Soil media is a conservative estimate and does not toke into account full soil capacity
l . LsMP= Length of basin perimter at toe of slope.
2. Bottom AsMP= Area at bottom of ponding
3. D ADJ= Adjusted Storoge Dept. Accounts for Storage Volume within slopes = D + ((O.S•B•D)"LBMp)/AsMp)]
4. Volume = AsMP x DADJ x Voids
IL I It ' )~;g--~· )= SIDES OF BASIN TO BE , .. ,,41),. ",h ., . A/.,Ji. · · LINED WITH
IMPERMEABLE LINER,
_ JO MIL THICK HDPE I J-I~. ·~ ·r 1:1 SLOPE (FOR ;<~;._~~ =>AEDIA LAYE:RS)
,. ~~ t:> 2~ ,, .,~~ 6-/NCH THICK LA YER OF
•etRDSEY£" WASHED PEA
GRA \IEL -CHOKER STONE
LAYER
~ ~u.~o.s-J...~-J..o. :::.
D ~o .i; )Le,it D)x L_
J"
2.25" ORIFICE PLAT£
76.86 IE (
po.~)~
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Ft t.to ¥\~
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1
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2 S I=-\ , Co ,c; x. 1Sn 1£. '2.St'-T) x. n-o FT ::: is tO,¾S'"o//2, ~OS::: DCt.d.j \
Ir '-ID n-z..
BMP 1 Drawdown Calculations
Media Depth
Choker Depth
Gravel Layer Depth
Orifice Offset
Orifice Diameter
Orifice Elevation
Co, Orifice Coefficient
D0, Dia (in)
H0, Effective Head (ft)1
Q, Discharge (cfs)
Ponding Volume (cf)
Drawdown Time (hr)
Co, Orifice Coefficient
D0, Dia (in)
H0, Effective Head (ft)1
Q, Discharge (cfs)
Co, Orifice Coefficient
D0, Di a (in)
H0, Effective Head (ft)1
I
Choker Volume {cf)
Drawdown Time (hr)
C0, Orifice Coefficient
D0, Dia (in)
H0, Effective Head (ft)1
Q, Discharge (cfs)
torage Layer (cf)
wn Time (hr)
r
1.5 ft
0.5 ft
2 ft
0.25 ft
2.25 inch
76.95 ft
0.6
2.25
5.66
0.32
Total Drawdown (hr)
80. 1
79.11
0.6
2.25
3.66
0.25
Total Drawdown (hr)
79.11
7 . 1
0.6
2.25
2.16
Total Drawdown (hr)
7 .61
76.
0.6
2.25
1.66
0.171
Total Drawdown (hr)
1 Effective Head is measured from centerline of the orifice to WS elevation
3.95
4.56
5.17
7.65
BMP 2 Drawdown Calculations
Media Depth
Choker Depth
Gravel Layer Depth
Orifice Offset
Orifice Diameter
Orifice Elevation
Co, Orifice Coefficient
D0, Dia (in)
H0, Effective Head (ft)1
Q, Discharge (cfs)
Ponding Volume (cf)
Drawdown Time (hr)
1.5
0.5
1
0.25
0.5
118.77
22.5
2 .5
0.6
0.5
3.73
4 .00
---------------------
120
Co, Orifice Coefficient 0.6
D0, Dia (in) 0.5
H0, Effective Head (ft)1 2.73
12
119.5
Co, Orifice Coefficient 0.6
D0, Dia (in) 0.5
H0, Effective Head (ft)1 1.23
Q, Discharge (cfs)
oker Volume (cf)
awdown Time (hr)
119.50
11 .77
r
Co, Orifice Coefficient 0.6
D0, Dia (in) 0.5
H0, Effective Hea d (ft)1 0.73
Q, Discharge (cfs) 0.006
yer (cf) 96.00
hr) 4.75
Total Drawdown (hr) 5.26
Total Drawdown (hr) 7.10
Total Drawdown (hr) 8.93
Total Drawdown (hr) 13.69
1 Effective Head is measured from centerline of the orifice to WS elevation
BMP 3 Drawdown Calculations
Media Depth
Choker Depth
Gravel Layer Depth
Orifice Offset
Orifice Diameter
Orifice Elevation
rf ce Elevat"on
Co, Orifice Coefficient
D0, Dia (in)
H0 , Effective Head (ft)1
Co, Orifice Coefficient
D0, Dia (in)
H0, Effective Head (ft)1
Soil Mix Volume (cf)
Drawdown Time (hr)
Co, Orifice Coefficient
D0, Dia (in)
H0, Effective Head (ft)1
Q, Discharge (cfs)
Choker Volume (cf)
Drawdown Time (hr)
Co, Orifice Coefficient
D0, Dia (in)
H0, Effective Head (ft)1
r f
1.5
0.5
1
0.25
1.2
109.6
11 .3
.3
0.6
1.2
3.7
15.
Total Drawdown (hr)
11 .
0.
0.6
1.2
2.70
274.
1.
Total Drawdown (hr)
110.
10.30
0.6
1.2
1.20
183.00
1.23
Total Drawdown (hr)
11 .
1 9.6
0.6
1.2
0.70
0.032
3
Total Drawdown (hr)
1Effective Head is measured from centerline of the orifice to WS elevation
3.49
4.72
5.95
9.16
ATTACHMENT 2
BACKUP FOR PDP HYDROMODIFICATION CONTROL MEASURES
[This is the cover sheet for Attachment 2.)
Indicate which Items are Included behind this cover sheet:
Attachment Contents Checklist
Sequence
Attachment 2a Hydromodification Management 0 Included
Exhibit (Required)
See Hydromodification Management
Exhibit Checklist on the back of this
Attachment cover sheet.
Attachment 2b Management of Critical Coarse 0 Exhibit showing project
Sediment Yield Areas (WMAA Exhibit drainage boundaries marked on
is required, additional analyses are WMAA Critical Coarse Sediment
optional) Yield Area Map (Required)
See Section 6.2 of the BMP Design Optional analyses for Critical Coarse
Manual. Sediment Yield Area Determination
J 6.2.1 Verification of Geomorphic
Landscape Units Onsite
J 6.2.2 Downstream Systems
Sensitivity to Coarse Sediment
J 6.2.3 Optional Additional Analysis
of Potential Critical Coarse
Sediment Yield Areas Onsite
Attachment 2c Geomorphic Assessment of Receiving 0 Not performed
Channels (Optional) J Included
See Section 6.3.4 of the BMP Design
Manual.
Attachment 2d Flow Control Facility Design and 0 Included as Part of Attachment 1
Structural BMP Drawdown
Calculations (Required)
See Chapter 6 and Appendix G of the
BMP Design Manual
23
Use this checklist to ensure the required information has been included on the
Hydromodification Management Exhibit:
The Hydromodification Management Exhibit must identify:
J 0 Underlying hydrologic soil group
J 0 Approximate depth to groundwater
J 0 Existing natural hydrologic features ( watercourses, seeps, springs, wetlands)
J 0 Critical coarse sediment yield areas to be protected (if present)
J 0 Existing topography
J 0 Existing and proposed site drainage network and connections to drainage offsite
J 0 Proposed grading
J 0 Proposed impervious features
J 0 Proposed design features and surface treatments used to minimize imperviousness
J 0 Point(s) of Compliance (POC) for Hydromodification Management
J 0 Existing and proposed drainage boundary and drainage area to each POC (when
necessary, create separate exhibits for pre-development and post-project conditions)
J 0 Structural BMPs for hydromodification management (identify location, type of BMP,
and size/detail)
24
ATTACHMENT 2b
\ \,
\ \ \ I \ \ \_ \
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Coastline Community Church
Storm Water Quality Management
WMAA Map with Potential Critical Coarse Sediment Areas
and Project Boundary
\ '1 -; \:.--------. --------
\
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I
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I
I I
I
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I I
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m
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March 2018
C HYDROMODIFICATION SCREENING
FOR
LA COSTA VALLEY SCHOOL SITE DEVELOPMENT
(SAN DIEGUITO UNION HIGH SCHOOL DISTRICT)
July 8, 2014
Wayne W. Chang, MS, PE 46548
c11111(B([[@1]Uili1Irn
Civil Engineering O Hydrology O Hydraulics O Sedimentation
P .0. Box 9496
Rancho Santa Fe, CA 92067
(858) 692-0760
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-TABLE OF CONTENTS -
Introduction ................................................................................................................................... 1
Domain of Analysis ...................................................................................................................... 2
Initial Desktop Analysis ................................................................................................................ 5
Field Screening ............................................................................................................................. 5
Conclusion .................................................................................................................................. 10
Figures ......................................................................................................................................... 11
APPENDICES
A. SCCWRP Initial Desktop Analysis
B. SCCWRP Field Screening Data
MAPPOCKET
Study Area Exhibit
As-Built Drawings
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INTRODUCTION
The City of Carlsbad's January 14, 2011, Standard Urban Storm Water Management Plan
(SUSMP) outlines low flow thresholds for hydromodification analyses. The thresholds are based
on a percentage of the pre-project 2-year flow (Q2), i.e., 0.1 Q2 (low flow threshold and high
susceptibility to erosion), 0.3Q2 (medium flow threshold and medium susceptibility to erosion),
or 0.5Q2 (high flow threshold and low susceptibility to erosion). A threshold of 0.1 Q2 represents
a downstream receiving conveyance system with a high susceptibility to erosion. This is the
default value used for hydromodification analyses and will result in the most conservative
(greatest) on-site facility sizing. A threshold of 0.3Q2 or 0.5Q2 represents downstream receiving
conveyance systems with a medium or low susceptibility to erosion, respectively. In order to
qualify for a medium or low susceptibility rating, a project must perform a channel screening
analysis based on a "hydromodification screening tool" procedure developed by the Southern
California Coastal Water Research Project (SCCWRP). The SCCWRP results are compared with
the critical shear stress calculator results from the County of San Diego's BMP Sizing Calculator
to establish the appropriate susceptibility threshold of low, medium, or high.
VICINITY
CITY OF' OCEANSIDE
PACIFIC
OCEAN
18
CITY
MAP
Vicinity Map
SITE
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This report provides hydromodification screening analyses for the La Costa Valley School Site
Development project by the San Dieguito Union High School District. The project is being
designed by Fuscoe Engineering, San Diego, Inc. (Fuscoe) and is located on the south side of
Calle Barcelona approximately 900 feet east of Paseo Aliso (see the Vicinity Map and the Study
Area Exhibit in the map pocket).
The site is currently mass-graded and undeveloped with the exception of three public storm drain
laterals and a public 42" RCP storm drain. The three laterals were installed during the prior
mass-grading to serve temporary on-site desilting basins. The existing 42" RCP storm drain at
the western edge of the site conveys run-on from a fourth on-site desilting basin as well as from
the residential development south of the site. All of the storm drains generally convey flow in a
northerly direction and outlet at one of two locations on the north side of Calle Barcelona. The
receiving waterbody just north of Calle Barcelona is a natural drainage course that flows in a
westerly direction.
The La Costa Valley School Site Development project proposes to construct an access road,
three buildings, athletic fields, and associated parking. The proposed buildings are a gymnasium,
electrical equipment room, and restrooms. The 28.03 acre project will include the demolition and
removal of an existing asphalt pedestrian path, existing desilting basins, and associated
infrastructure. The proposed improvements will include new landscaping, flow-through planters,
pervious pavement, permeable pavers, sidewalk, maintenance access road, storm drain
infrastructure and other improvements. The project's storm runoff will be captured by the
aforementioned laterals and 42" RCP storm drain. Consequently, the runoff will be discharged
into the natural downstream channel from one of the two existing outlet locations.
The SCCWRP screening tool requires both office and field work to establish the vertical and
lateral susceptibility of a natural downstream receiving channel to erosion. The vertical and
lateral assessments are performed independently of each other although the lateral results can be
affected by the vertical rating. A screening analysis was performed to assess the low flow
threshold for the project's points of compliance, which are at each of the two existing storm
drain outlets into the natural channel.
The initial step in performing the SCCWRP screening analysis is to establish the domain of
analysis and the study reaches within the domain. This is followed by office and field
components of the screening tool along with the associated analyses and results. The following
sections cover these procedures in sequence.
DOMAIN OF ANALYSIS
SCCWRP defines an upstream and downstream domain of analysis, which establish the study
limits. The County of San Diego's HMP specifies the downstream domain of analysis based on
the SCCWRP criteria. The HMP indicates that the downstream domain is the first point where
one of these is reached:
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• at least one reach downstream of the first grade control point (preferably second
downstream grade control location)
• tidal backwater/lentic waterbody
• equal order tributary
• accumulation of 50 percent drainage area for stream systems or 100 percent drainage area
for urban conveyance systems (storm drains, hardened channels, etc.)
The upstream limit is defined as:
• proceed upstream for 20 channel top widths or to the first grade control point, whichever
comes first. Identify hard points that can check headward migration and evidence of
active headcutting.
SCCWRP defines the maximum spatial unit, or reach (a reach is circa 20 channel widths), for
assigning a susceptibility rating within the domain of analysis to be 200 meters (656 feet). If the
domain of analysis is greater than 200 meters, the study area should be subdivided into smaller
reaches of less than 200 meters for analysis. Most of the units in the HMP' s SCCWRP analysis
are metric. Metric units are used in this report only where given so in the HMP. Otherwise
English units are used.
Downstream Domain of Analysis
The downstream domain of analysis for a study area is determined by assessing and comparing
the four bullet items above. As discussed in the Introduction, the project has a point of
compliance (POC) at each of the two storm drain outlets into the receiving natural channel along
the north side of Calle Barcelona. Therefore, a downstream domain of analysis location will be
selected below the downstream-most (westerly) POC.
Per the first bullet item, the first permanent grade control point was located below the westerly
POC through a site investigation and review of aerial photographs and as-built drawings. The
first permanent grade control occurs at the Paseo Aliso roadway crossing of the channel, which is
approximately 900 feet downstream of the westerly POC. According to as-built drawing 325-lA
for Arroyo La Costa Unit 2 sheet 16 (see map pocket), a 48-inch RCP conveys the channel flow
across Paseo Aliso. This culvert was observed in the field. Since Paseo Aliso is a public road
with a non-erodible culvert, it is considered a permanent grade control. The roadway
embankment and culvert will prevent erosion (i.e., control the grade) of the upstream channel
bed.
The second bullet item is the tidal backwater or lentic ( standing or still water such as ponds,
pools, marshes, lakes, etc.) waterbody location. The nearest significant tidal backwater or lentic
waterbody is Batiquitos Lagoon, which, from Google Earth, is over a mile northwest from the
site. Since the lagoon is considerably downstream of the grade control, the lagoon will not
govern for establishing the downstream domain of analysis location.
The final two bullet items are based on 50 and 100 percent tributary drainage areas. From the
Watershed Exhibit in Appendix A, the drainage area tributary to the westerly POC covers 329.25
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acres. It is clear from the exhibit that this drainage area does not increase by 50 to 100 percent
between the westerly POC and the permanent grade control. Therefore, none of the tributary
drainage area criteria will govern in establishing the downstream domain of analysis location.
Based on the above information, the downstream domain of analysis is established by the
permanent grade control criteria because this is the first point reached among the various criteria.
Per the first bullet item, the downstream domain of analysis is one reach below the grade control
point or preferably the second grade control location. As-built drawing 325-lA sheet 16 shows
that the second grade control location occurs at the end of the natural channel just east of El
Camino Real at the intersection with Calle Barcelona. The channel transitions into a double 6-
foot by 5-foot box culvert at this location, which forms the second grade control location (see the
Study Area Exhibit). The box culvert was verified in the field. Therefore, the downstream
domain of analysis location was selected to be at the second grade control below the POCs,
which is at the entrance to the box culvert at El Camino Real and Calle Barcelona.
Upstream Domain of Analysis
The upstream domain of analysis must be established for the natural channel. The channel
continues upstream of both POCs to another public road crossing at A venida Helecho, which is
approximately 1,400 feet upstream of the easterly POC (see the Study Area Exhibit). According
to Drawing No. 325-lA for Arroyo La Costa Unit 2 sheet 11 (see map pocket), the road crossing
contains a 42" RCP so it is a permanent grade control. Therefore, the culvert exit at the lower
end A venida Helecho was selected as the upstream domain of analysis location.
Study Reaches within Domain of Analysis
The total domain of analysis ( or overall study reach) extends from the culvert exit at the lower
end of A venida Helecho to the culvert entrance at the intersection of Calle Barcelona and El
Camino Real. The total domain of analysis covers approximately 3,470 feet (1,058 meters). The
domain of analysis was subdivided into four natural study reaches with similar characteristics
(see the Study Area Exhibit). Reach 1 extends 1,495 feet (456 meters) from the upstream domain
of analysis location down to the easterly POC. Reach 2 extends 655 feet (200 meters) from the
easterly POC to the westerly POC. Reach 3 extends 850 feet (259 meters) from the westerly
POC to Paseo Aliso. Reach 4 extends 470 feet (143 meters) from Paseo Aliso to the downstream
domain of analysis location.
Reach 1 and 3 are longer than the 656 feet (200 meters) maximum reach length specified by
SCCWRP. Review of topographic mapping, aerial photographs, and field conditions reveals that
the physical ( channel geometry and longitudinal slope), vegetative, hydraulic, and soil conditions
within these two reaches are relatively uniform. Subdividing the reaches into smaller subreaches
of less than 656 feet will not yield significantly varying results within a reach. Although the
screening tool was applied across the entire length of each study reach, the results will be similar
for shorter subreaches within each reach.
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INITIAL DESKTOP ANALYSIS
After the domain of analysis is established, SCCWRP requires an "initial desktop analysis" that
involves office work. The initial desktop analysis establishes the watershed area, mean annual
precipitation, valley slope, and valley width. These terms are defined in Form 1, which is
included in Appendix A. SCCWRP recommends the use of National Elevation Data (NED) to
determine the watershed area, valley slope, and valley width. The NED data is similar to USGS
mapping. For this report, USGS quadrangle mapping was used to determine the watershed area
tributary to each reach (see the Watershed Exhibit in Appendix A).
The mean annual precipitation is provided by the County of San Diego's BMP Sizing Calculator
(see Appendix A) and is 13.3 inches.
The valley slope of each study reach was determined from the I -foot contour interval mapping
prepared for the project, where available, and the City's 2-foot contour interval topographic
mapping for the remaining area. The valley slope is the longitudinal slope of the channel bed
along the flow line, so it is determined by dividing the elevation difference within a reach by the
flow path. The 1-and 2-foot contour mapping sources were used because they will provide more
precise results than NED data.
The valley width is the bottom width of the main creek channel. The average valley width within
each reach was estimated from the 1-and 2-foot contour interval topographic mapping and as-
built plans. The valley slope and valley width for each reach are summarized in Table 1.
These values were input to a spreadsheet to calculate the simulated peak flow, screening index,
and valley width index outlined in Form 1. The input data and results are tabulated in Appendix
A. This completes the initial desktop analysis.
Reach Tributary Area, sq. mi. Valley Slope, m/m Valley Width, m
-··
1 0.4185 0.0181 6.1
-
2 0.5145 0.0107 12.2
3 0.5583 0.0141 12.2
-
4 0.6552 0.0043 15.2
Table 1. Summary of Valley Slope and Valley Width
FIELD SCREENING
After the initial desktop analysis is complete, a field assessment must be performed. The field
assessment is used to establish a natural channel's vertical and lateral susceptibility to erosion.
SCCWRP states that although they are admittedly linked, vertical and lateral susceptibility are
assessed separately for several reasons. First, vertical and lateral responses are primarily
controlled by different types of resistance, which, when assessed separately, may improve ease
of use and lead to increased repeatability compared to an integrated, cross-dimensional
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assessment. Second, the mechanistic differences between vertical and lateral responses point to
different modeling tools and potentially different management strategies. Having separate
screening ratings may better direct users and managers to the most appropriate tools for
subsequent analyses.
The field screening tool uses combinations of decision trees and checklists. Decision trees are
typically used when a question can be answered fairly definitively and/or quantitatively ( e.g., d50
< 16 mm). Checklists are used where answers are relatively qualitative ( e.g., the condition of a
grade control). Low, medium, high, and very high ratings are applied separately to the vertical
and lateral analyses. When the vertical and lateral analyses return divergent values, the most
conservative value shall be selected as the flow threshold for the hydromodification analyses.
Visual observation reveals that all of the study reaches contain a densely vegetated channel with
mature cover of primarily reeds, scattered trees, and brush (see the figures following the report
text). The vegetative density extends uniformly across the channel bottom and sides. Due to the
vegetative cover, riprap energy dissipaters at each POC, and lack of significant erosion noted
during the site investigation, the vertical and lateral stability was anticipated to have a limited
susceptibility to erosion.
Vertical Stability
The purpose of the vertical stability decision tree (Figure 6-4 in the County of San Diego HMP)
is to assess the state of the channel bed with a particular focus on the risk of incision (i.e., down
cutting). The decision tree is included in Figure 11. The first step is to assess the channel bed
resistance. There are three categories defined as follows:
1. Labile Bed -sand-dominated bed, little resistant substrate.
2. Transitional/Intermediate Bed -bed typically characterized by gravel/small cobble,
Intermediate level of resistance of the substrate and uncertain potential for armoring.
3. Threshold Bed (Coarse/Armored Bed) -armored with large cobbles or larger bed
material or highly-resistant bed substrate (i.e., bedrock).
Channel bed resistance is a function of the bed material and vegetation. The figures after this
report text contain photographs of the natural channels in each study reach. A site investigation
and the figures indicate that the vegetative cover throughout each natural channel within Reaches
1 through 4 is mature, dense, and uniform (see Figures 1 through 9). The vegetation in the
channel areas was so dense that the channel was either difficult to access or for the most part not
possible to access at all. The vegetation consists of a variety of mature grasses, reeds, shrubs, and
trees. Vegetation prevents bed incision because its root structure binds soil and because the
aboveground vegetative growth reduces flow velocities. Table 5-13 from the County of San
Diego's Drainage Design Manual outlines maximum permissible velocities for various channel
linings (see Table 5-13 in Appendix B). Maximum permissible velocity is defined in the manual
as the velocity below which a channel section will remain stable, i.e., not erode. Table 5-13
indicates that a fully-lined channel with unreinforced vegetation has a maximum permissible
velocity of 5 feet per second (fps). Due to the dense cover and mature vegetation, the permissible
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velocity when erosion can initiate is likely greater than 5 fps in the natural channel areas. Table
5-13 indicates that 5 fps is equivalent to an unvegetated channel containing cobbles (grain size
from 64 to 256 mm) and shingles (rounded cobbles). In comparison, coarse gravel (19 to 75 mm)
has a maximum permissible velocity of 4 fps. Based on this information, the uniformly vegetated
channel in Reaches 1 through 4 have an equivalent grain size of at least 64 mm, which is
comparable to a transitional/intermediate bed.
There are several factors that establish the erodibility of a channel such as the flow rate (i.e., size
of the tributary area), grade controls, channel slope, vegetative cover, channel planform, etc. The
Introduction of the SCCWRP Hydromodification Screening Tools: Field Manual identifies
several of these factors. When multiple factors influence erodibility, it is appropriate to perform
the more detailed SCCWRP analysis, which is to analyze a channel according to SCCWRP' s
transitional/intermediate bed procedure. This requires the most rigorous steps and will generate
the appropriate results given the range of factors that define erodibility. The transitional/
intermediate bed procedure takes into account that bed material may fall within the labile
category (the bed material size is used in SCCWRP's Form 3 Figure 4), but other factors may
trend towards a less erodible condition. Dr. Eric Stein from SCCWRP, who co-authored the
Hydromodification Screening Tools: Field Manual in the Final Hydromodification Management
Plan (HMP), indicated that it would be appropriate to analyze channels with multiple factors that
impact erodibility using the transitional/intermediate bed procedure. Consequently, this
procedure was used to produce more accurate results for each study reach.
Transitional/intermediate beds cover a wide susceptibility/potential response range and need to
be assessed in greater detail to develop a weight of evidence for the appropriate screening rating.
The three primary risk factors used to assess vertical susceptibility for channels with
transitional/intermediate bed materials are:
1. Armoring potential -three states (Checklist 1)
2. Grade control -three states (Checklist 2)
3. Proximity to regionally-calibrated incision/braiding threshold (Mobility Index Threshold
-Probability Diagram)
These three risk factors are assessed using checklists and a diagram (see Appendix B), and the
results of each are combined to provide a final vertical susceptibility rating for the
intermediate/transitional bed-material group. Each checklist and diagram contains a Category A,
B, or C rating. Category A is the most resistant to vertical changes while Category C is the most
susceptible.
Checklist 1 determines armoring potential of the channel bed. The channel bed along each of the
four reaches is within category B, which represents intermediate bed material within unknown
armoring potential due to a surface veneer and dense vegetation. The soil was probed and
penetration was relatively difficult through the underlying layer of each reach. Due to the dense
vegetative growth in the reaches, the armoring potential could have been rated higher in those
reaches, but Category B was conservatively (i.e., more potential for channel incision) chosen.
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Checklist 2 determines grade control characteristics of the channel bed. SCCWRP states that
grade controls can be natural. Examples are vegetation or confluences with a larger waterbody.
As indicated above and verified with photographs, Reaches 1 through 4 contain dense vegetation
that was mostly impossible to enter on foot (see Figures 1 through 9). The plant roots and tree
trunks serve as a natural grade control. The spacing of these is much closer than the 50 meters or
2/Sv values identified in the checklist. Further evidence of the effectiveness of the natural grade
controls is the absence of headcutting and mass wasting (large vertical erosion of a channel
bank). Based on this information, Reaches 1 through 4, are within Category A on Checklist 2.
The Screening Index Threshold is a probability diagram that depicts the risk of incising or
braiding based on the potential stream power of the valley relative to the median particle
diameter. The threshold is based on regional data from Dr. Howard Chang of Chang Consultants
and others. The probability diagram is based on d50 as well as the Screening Index determined in
the initial desktop analysis (see Appendix A). d50 is derived from field conditions. Figure 10
contains a photograph of the typical bed material near the center of the study area, which
contains a mix of silt, sand, and some gravel. A gravelometer is included in the photograph for
reference. Each square on the gravelometer indicates grain size in millimeters (the squares range
from 2 mm to 180 mm). As discussed above, the equivalent grain size for the densely-vegetated
channels in Reaches 1 through 4 is at least 64 mm. The Screening Index Threshold diagram
shows that the 50 percent probability of incising or braiding for a d50 of 64 mm has an index of at
least 0.101 (in red rectangle on diagram). The Screening Index for these four reaches calculated
in Appendix A varies from 0.0069 to 0.0240. Since each reach's Screening Index value is less
than the 50 percent value, Reaches 1 through 4 fall within Category A.
The overall vertical rating is determined from the Checklist 1, Checklist 2, and Mobility Index
Threshold results. The scoring is based on the following values:
Category A= 3, Category B = 6, Category C = 9
The vertical rating score for each of the four reaches is based on these values and the equation:
V . 1 R . [( . d 1)112 • • d ]112 ert1ca atmg = armonng x gra e contro x screenmg m ex score
= [(6 x 3)112 x 3]112 (Note: each of the four reaches has similar values)
= 3.6
Since the vertical rating is less than 4.5, each reach has a low vertical susceptibility to erosion.
Lateral Stability
The purpose of the lateral decision tree (Figure 6-5 from County of San Diego HMP included in
Figure 12) is to assess the state of the channel banks with a focus on the risk of widening.
Channels can widen from either bank failure or through fluvial processes such as chute cutoffs,
avulsions, and braiding. Widening through fluvial avulsions/active braiding is a relatively
straightforward observation. If braiding is not already occurring, the next logical step is to assess
the condition of the banks. Banks fail through a variety of mechanisms; however, one of the most
important distinctions is whether they fail in mass (as many particles) or by fluvial detachment of
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individual particles. Although much research is dedicated to the combined effects of weakening,
fluvial erosion, and mass failure, SCCWRP found it valuable to segregate bank types based on
the inference of the dominant failure mechanism ( as the management approach may vary based
on the dominant failure mechanism). A decision tree (Form 4 in Appendix B) is used in
conducting the lateral susceptibility assessment. Definitions and photographic examples are also
provided below for terms used in the lateral susceptibility assessment.
The first step in the decision tree is to determine if lateral adjustments are occurring. The
adjustments can take the form of extensive mass wasting (greater than 50 percent of the banks
are exhibiting planar, slab, or rotational failures and/or scalloping, undermining, and/or tension
cracks). The adjustments can also involve extensive fluvial erosion (significant and frequent
bank cuts on over 50 percent of the banks). Neither mass wasting nor extensive fluvial erosion
was evident within any of the reaches during a field investigation. The banks are intact in the
photographs included in the figures and support mature plants. Due to the dense vegetation in
most areas, photographs representative of the banks were difficult to take. Nonetheless, the dense
vegetation supports the absence oflarge lateral adjustments.
The next step in the Form 4 decision tree is to assess the consolidation of the bank material. The
banks were moderate to well-consolidated. This determination was made because the banks were
difficult to penetrate with a probe. In addition, the banks showed limited evidence of crumbling
and were composed of well-packed particles.
Form 6 (see Appendix B) is used to assess the probability of mass wasting. Form 6 identifies a
10, 50, and 90 percent probability based on the bank angle and bank height. The 2-foot contour
interval topographic mapping indicates that the average natural bank angle is no greater than 2 to
1 (horizontal to vertical) or 26.6 degrees in any of the reaches. Form 6 shows that the probably of
mass wasting and bank failure has less than 10 percent risk for a 26.6 degree bank angle or less
regardless of the bank height.
The final two steps in the Form 4 decision tree are based on the braiding risk determined from
the vertical rating as well as the Valley Width Index (VWI) calculated in Appendix A. If the
vertical rating is high, the braiding risk is considered to be greater than 50 percent. Excessive
braiding can lead to lateral bank failure. For all four study reaches, the vertical rating is low, so
the braiding risk is less than 50 percent. Furthermore, a VWI greater than 2 represents channels
unconfined by bedrock or hillslope and, hence, subject to lateral migration. The VWI
calculations in the spreadsheet in Appendix A show that the VWI for each reach is less than 2.
From the above steps, the lateral susceptibility rating is low for each of the four study reaches
(red circles are included on the Form 4: Lateral Susceptibility Field Sheet decision tree in
Appendix B showing the decision path). A review of aerial photographs and site visit confirms a
lack of braiding or lateral migration throughout the natural channels.
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CONCLUSION
The SCCWRP channel screening tools were used to assess the downstream channel
susceptibility for the La Costa Valley School Site Development project being designed by
Fuscoe Engineering, San Diego, Inc. The project runoff will ultimately be collected by one of
two existing public storm drain systems that outlet into an unnamed natural channel just north of
the site. Each outlet is a point of compliance. Based on the points of compliance, the natural
channel was assessed from Avenida Helecho to El Camino Real (domain of analysis). The
assessment was performed based on office analyses and field work. The results indicate a low
susceptibility for vertical and lateral channel erosion for the entire study area.
The HMP requires that these results be compared with the critical stress calculator results
incorporated in the County of San Diego's BMP Sizing Calculator. The BMP Sizing Calculator
critical stress results are included in Appendix B for all four reaches. Based on these values, the
critical stress results returned a low susceptibility to erosion. Therefore, the SCCWRP analyses
and critical stress calculator demonstrate that the project can be designed assuming a low
susceptibility, i.e., 0.5Q2.
The SCCWRP results are consistent with the physical condition of the natural channel within the
domain of analysis with densely-vegetated throughout. None of the four study reaches exhibit
signs of extensive, ongoing erosion.
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Figure 1. Looking Downstream towards Reach 1
Figure 2. Looking Upstream towards Reach 1 from Easterly POC
1 I
Figure 3. Looking Towards Easterly POC, Reach 1, and Reach 2
Figure 4. Looking Downstream towards Reach 2 from Easterly POC
12
Figure 5. Looking Upstream towards Reach 2 from Westerly POC
Figure 6. Looking towards Westerly POC and Downstream at Reach 3
13
Figure 7. Looking Upstream towards Reach 3 from Paseo Aliso
Figure 8. Looking Downstream towards Reach 4 from Paseo Aliso
14
~ . . ... ;· . . .. ... .. .,.
~.~, l .J ;,-. •
..
Figure 9. Looking Upstream towards Reach 4
Figure 10. Gravelometer Near Middle of Study Area
15
LABILE BED
• San<klorninElled
•cir.ii< 18mm
• 'Iii, aurfsce pnd ,. 25%
• I..OOHly-i)aCbd
HIGtl
CHANNEL BED RESISTA.NCE
INTERMEDIATE BED
• MQderately-lO looe,ely-
ped(ed colll>le J g'8'11el
• Hardpan of uncertain
Clapll'I, .emnt arocmilly
EXAMINE RISK FACTQRS
I Qrade 00n'1!1
• ermoon11 JDOt«itiel
• proidmity to incision llnehold
COARSE/ARMORED BED
•<lsii > 128mm
• Boulder J Iii~ cobble
• tighll~-packed
• <6% sand
• Conllnuou, t)edrock
• Continuous cancJ1ll9
90 to bed &r'Odibiity
checklists and incision
diagram check list
Fil out SCCWRP ~
Ctfterla to determine If 1he
receiving cti1111nel ti. e l-UGH,
MEDIU r.t. or LOW 11uacaptibility
Figure 6-4. SCCWRP Vertical Susceptibility
Figure 11. SCCWRP Vertical Channel Susceptibility Matrix
16
b) ~lrnlly IQ
bnuda,q
JJm. NO
• Fuly ll'Tll(Jrecl I bedrocll: IMlllk
1118bllut,:i,, In ~ c:onc1,o,,
• l'tc, 1Mdll'loe d lftllll
t;lrmlrlllln I a""'l!llllnt
• Fully CO!f'rneQ. diflll:II~
conneca.d ID hjllld& w.i-1
Briheq,I
,.10'1',.los,llc
l'llk IDr angle
MIIDYWl>2
LAIEAALL Y AOJU6TABI.E"I
i'f01111,, or Mal cr,I, lmted lo
bellldl end ~
AU BANK STRATA
CONSOLIDATED
NO.UDINOT(IE?
Corl•/
,-1a11a,d
>84mm
Figure 6-5. Lateral Channel Susceptibility
Fine
un0111'110id-.l
I\NOVWU2
Figure 12. SCCWRP Lateral Channel Susceptibility Matrix
17
Fine
unco""" Ida led
ANll\M'l >2
APPENDIX A
SCCWRP INITIAL DESKTOP ANALYSIS
FORM 1: INITIAL DESKTOP ANALYSIS
Complete all shaded sections.
IF required at multiple locations, circle one of the following site types:
Applicant Site / Upstream Extent / Downstream Extent
Location: Latitude: __ 3_3_.0_7_4_1 ____ _ Longitude: __ -1_1_7_.2_5_4_9 ___ _
Description (river name, crossing streets, etc.): La Costa Valley School Site Development
south of Calle Barcelona, west of Paseo Aliso.
GIS Parameters: The International System of Units (SI) is used throughout the assessment as the field
standard and for consistency with the broader scientific community. However, as the singular exception, US
Customary units are used for contributing drainage area (A) and mean annual precipitation (P) to apply regional flow
equations after the USGS. See SCCWRP Technical Report 607 for example measurements and "Screening Tool
Data Entry.xis" for automated calculations.
Form 1 Table 1. Initial desktop analysis in GIS.
Symbol
A
en ~ V, :t:!'
(I) (I) C: .c ·-::I ~ ai .c .l!l 0.,!!1 p ~ e °' a. C: ~
Sv
<I) (I) :e -(I) .l!l a.·-0 C: w. '-::I a.-~~
u5
Variable
Area
(mi2)
Mean annual
precipitation
(in)
Valley slope
(m/m)
Valley width
(m)
Description and Source
Contributing drainage area to screening location via published
Hydrologic Unit Codes (HUCs) and/ors 30 m National Elevation Data
(NED), USGS seamless server
Area-weighted annual precipitation via USGS delineated polygons using
records from 1900 to 1960 (which was more significant in hydrologic
models than polygons delineated from shorter record lengths)
Valley slope at site via NED, measured over a relatively homogenous
valley segment as dictated by hillslope configuration, tributary
confluences, etc., over a distance of up to ~500 m or 10% of the main-
channel length from site to drainage divide
Valley bottom width at site between natural valley walls as dictated by
clear breaks in hillslope on NED raster, irrespective of potential
armoring from floodplain encroachment, levees, etc. (imprecise
measurements have negligible effect on rating in wide valleys where
VWI is » 2, as defined in lateral decision tree)
Value
See attached
Form 1 table
on next page
for calculated
values for each
reach.
Form 1 Table 2. Simplif ied peak flow, screening index, and valley width index. Values for this
table should be calculated in the sequence shown in this table, using values from Form 1 Table 1.
Symbol Dependent Variable Equation Required Units Value
O1oc1s 10-yr peak flow (ft3/s) O10cts = 18.2 * A 0·87 * P 0·77 A (mi2)
P (in) See attached
010 10-yr peak flow (m3/s) 0 10 = 0.0283 . O1oc1s O,octs (ft3/s) Form 1 table
INDEX 10-yr screening index (m 15/s05) INDEX= Sv*O,o 0.5 Sv (m/m) on next page 0 10 (m3/s) for calculated
Wref Reference width (m) Wref = 6.99 • 0 10 0.438 0 10 (m3/s) values for each
VWI Valley width index (m/m) VWI = WvMlret Wv(m) reach.
W,et (m)
(Sheet 1 of 1)
B-3
SCCWRP FORM 1 ANALYSES
Area Mean Annual Precip. Valley Slope Valley Width 10-Year Flow 10-Year Flow
Reach A, sq. mi. P, inches Sv, m/m Wv,m QlOcfs, cfs QlO, ems
1 0.4185 13.3 0.0181 6.1 63 1.8
2 0.5145 13.3 0.0107 12.2 75 2.1
3 0.5583 13.3 0.0141 12.2 80 2.3
4 0.6552 13.3 0.0043 15.2 92 2.6
10-Year Screening Index Reference Width Valley Width Index
Reach INDEX Wref, m VWI, m/m
1 0.024 9.0 0.68
2 0.016 9.7 1.26
3 0.021 10.0 1.22
4 0.007 10.6 1.43
Notes:
The areas were obtained from the Watershed Exhibit.
The mean annual preci pitation was obtained from the County of San Diego's BMP Calculator.
The valley slope was determined from the elevations and flow lengths from the Study Area Exhibit.
The valley width was estimated from the topographic mapping on the Study Area Exhibit and a site investigation.
The 10-year flow, screening index, reference w idth, and valley width index are calculated from the equations on Form 1.
0 0 0 -
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Result View
Define Drainage Basins Basin Agua Hedionda Watershed Pro1ect Ranch Castera & El Camino Real Widening
L Basin
Manage Your Basins I Name
Create a new Basin by clicking the New button and scroll down to view
entry_ Alternatively, select an existing Basin from table and view
properties below_ Click Edit button to change Basin properties then
press Save to commit changes.
IM1& NfijN AA
Description: [Rancho Costera & ECR Drainage Basn;
Design Go.ii: I Treatment + Row Control G
Rainf.111 Basin: !Oceanside ~-B
Agua Hed1onda Watershed
Point of Compliance: ~arious Storm Drain Outfals
Project Ba.sin Area (ac}: j1 ◄ 29 I Mean Annual Precipition (in): j13.3
MEAN ANNUAL PRECIPITATION FROM COUNTY BMP SIZING CALCULATOR
Chapter 5. Open Channels
Table 5-13 Maximum Permissible Velocities for Lined and Unlined Channels
Material or Lining
Natural and Improved Unlined Channels
Maximum Permissible
Average Velocity* (ft/sec)
Fine Sand, Colloidal .................................................................................................................... 1.50
Sandy Loam, Noncolloidal .......................................................................................................... 1.75
Silt Loam, Noncolloidal. ............................................................................................................... 2.00
Alluvial Silts, Noncolloidal ........................................................................................................... 2.00
Ordinary Firm Loam .................................................................................................................... 2.50
Volcanic Ash ............................................................................................................................... 2.50
Stiff Clay, Very Colloidal.. ............................................................................................................ 3.75
Alluvial Silts, CollO'dal ................................................................................................................. 3.75
Shales And Hardpans ................................................................................................................. 6.00
Fine Gravel .................................................................................................................................. 2.50
Graded Loam To Cobbles When Noncolloidal ........................................................................... 3.75
G1cn.ltH.I Sill:; To CulJIJle:; Wilen Colloitlc1l... ................................................................................. 4 .00
Coarse Gravel, Noncolloidal ....................................................................................................... 4.00
Cobbles And Shingles.·-----···~----····-····--···························· .................................. 5.00
Sandy Silt ................................................................................................................................... 2.00
Silty Clay ..................................................................................................................................... 2.50
Clay ............................................................................................................................................. 6.00
Poor Sedimentary Rock .............................................................................................................. 10.0
Fully-Lined Channels
Unreinforced Vegetation _______________ ······-··············-·· ___ ·-····---··--· 5.0
Reinforced Turf .......................................................................................................................... 10.0
Loose Riprap ................................................................................................................ per Table 5-2
Grouted Riprap ........................................................................................................................... 25.0
Gabions ...................................................................................................................................... '15.0
Soil Cement ................................................................................................................................ 15.0
Concrete ..................................................................................................................................... 35.0
• Maximum permissible velocity listed /Jere Is basic guideline; higher design velocities may be used, provided approprtate
technical documentatio1 rrom manuracturer.
San Diego County Drainage Design Manual
July 2005
Page 5-43
D
X
D
Form 3 Support Materials
Form 3 Checklists 1 and 2, along with information recording in Form 3 Table 1,
are intended to support the decisions pathways illustrated in
Form 3 Overall Vertical Rating for Intermediate/Transitional Bed.
A
B
C
Form 3 Checklist 1: Armoring Potential
A mix of coarse gravels and cobbles that are tightly packed with <5%
surface material of diameter <2 mm
Intermediate to A and C or hardpan of unknown resistance, spatial extent
(longitudinal and depth), or unknown armoring potential due to surface
veneer covering gravel or coarser layer encountered with probe
Gravels/cobbles that are loosely packed or >25% surface material of
diameter <2 mm
Form 3 Figure 2. Armoring potential photographic supplement for assessing intermediate beds
(16 < d50 < 128 mm) to be used in conjunction with Form 3 Checklist 1.
(Sheet 2 of 4)
REACH 1 THROUGH 4 RESULTS
8-7
X A
D B
D C
Form 3 Checklist 2: Grade Control
Grade control is present with spacing <50 m or 2/Sv m
• No evidence of failure/ineffectiveness, e.g., no headcutting (>30 cm), no
active mass wasting (analyst cannot say grade control sufficient if mass-
wasting checklist indicates presence of bank failure), no exposed bridge
pilings, no culverts/structures undermined
• Hard points in serviceable condition at decadal time scale, e.g., no apparent
undermining, flanking, failing grout
• If geologic grade control, rock should be resistant igneous and/or
metamorphic; For sedimentary/hardpan to be classified as 'grade control', it
should be of demonstrable strength as indicated by field testing such as
hammer tesUborings and/or inspected by appropriate stakeholder
Intermediate to A and C -artificial or geologic grade control present but
spaced 2/Sv m to 4/Sv m or potential evidence of failure or hardpan of
uncertain resistance
Grade control absent, spaced >100 m or >4/Sv m, or clear evidence
of ineffectiveness
Form 3 Figure 3. Grade-control (condition) photographic supplement for assessing intermediate
beds (16 < d50 < 128 mm) to be used in conjunction with Form 3 Checklist 2.
(Sheet 3 of 4)
REACH 1 THROUGH 4 RESULTS
8 -8
Note: the equivalent d50 in each reach taking dense vegetation into account is 64 mm. The Screening
Index Values from the Appendix A spreadsheet (0.0069 to 0.0240) for each reach are less than the 50%
Risk values for 64 mm (0.101 ), so the risk of incising is less than 50%.
Regionally-Calibrated Screening Index Threshold for Incising/Braiding
For transitional bed channels (d50 between 16 and 128 mm) or labile beds (channel not incised
past critical bank height), use Form 3 Figure 3 to determine Screening Index Score and complete
Form 3 Table 1.
-1 .,.,
0 ~ 1'.ti : o .S 0.1
Z "" -o 0 q 0.01
Cl) •
0.001
0.1 1 dso (mm) 10
♦ Stable x Braided
10% risk --50% risk
X
100
+ Incising
900/o risk
GIS-derived: 1 O-y1 flow & volley slope
Field-derived: d50 ( l 00-pebble count)
128 0.145
C: 96 0.125 0 "iii E VI 80 0.114 ~ E
Cl CD 64 0.101 ~ ...
0 f,J
:c J 48 0.087 VI '6,
0 32 0.070 ..J
16 0.049
8 0.031 0) E 4) E 4 0.026 0::
0 CD
:c ... 2 0.022 .!!! V .3 J 0.018
0.5 0.015
Form 3 Figure 4. Probability of incising/braiding based on logistic regression of Screening Index
and dso to be used in conjunction with Form 3 Table 1.
Form 3 Table 1. Values for Screening Index Threshold (probability of incising/braiding) to be used
in conjunction w ith Form 3 Figure 4 (above) to complete Form 3 Overall Vertical Rating for
Intermediate/Transitional Bed (below) .. Screening Index Score: A = <50% probability of incision
for current 0 10, valley slope, and d50; B = Hardpan/d50 indeterminate; and C = 2:,50% probability of
incising/braiding for current 010, valley slope, and dso-
dso (mm)
From Form 2
S/O10o.s (m1.s,so.s)
From Form 1
Sv *010 o.s (m 1.s,so.s)
50% risk of incising/braiding
from table in Form 3 Figure 3 above
Screening Index Score
(A, B, C)
Overall Vertical Rating for Intermediate/Transitional Bed
Calculate the overall Vertical Rating for Transitional Bed channels using the formula below.
Numeric values for responses to Form 3 Checklists and Table 1 as follows: A = 3, B = 6, C = 9.
Vertical Rating= {(✓armoring• grade control)~ screening index score}
Vertical Susceptibility based on Vertical Rating: <4.5 = LOW; 4.5 to 7 = MEDIUM; and >7 = HIGH.
(Sheet 4 of 4)
REACH 1 THROUGH 4 RESULTS
8 -9
FORM 4: LATERAL SUSCEPTIBIL TY FIELD SHEET
Circle appropriate nodes/pathway for proposed site
OR use sequence of questions provided in Form 5.
LOW
•Fully armored f
bedrock bank .
stabilization in good
condition
•No evidence of
chute ,formation l
avulSIOflS • ·
•Fully conAried,,,Qtrectly
connect,ed to _tiiUs~ope,
VWI ~ 1
Vertical Vertical HIGH
·:? high < high Vertical
~high
(Sheet 1 of 1)
REACH 1 THROUGH 4 RESULTS
B -10
FORM 6: PROBABILITY OF MASS WASTING BANK FAILURE
If mass wasting is not currently extensive and the banks are moderately-to well-consolidated, measure
bank height and angle at several locations (i.e., at least three locations that capture the range of
conditions present in the study reach) to estimate representative values for the reach. Use Form 6 Figure
1 below to determine if risk of bank failure is >10% and complete Form 6 Table 1. Support your results
with photographs that include a protractor/rod/tape/person for scale.
Bank Angle Bank Height Corresponding Bank Height for
(degrees) (m) 10% Risk of Mass Wasting (m)
(from Field) (from Field} (from Form 6 Figure 1 below)
Left Bank <26.6 (2: 1) Varies Any
Right Bank <26.6 {2:1} Varies Any_
probability of mass wasting 1c
in moderately /well consolidated banks "9
30
0 Stable 10% Risk -50% Risk 90%Risk X Unstable 35
4 40 X \ 45 0 )( 0 X 50
3 )( 55 E X X ... 0 0 60 .r=
cP°' 0 X QO 2 0 65 'iii J: X
~ o oo 0 x>< X 70 C:
~
o~o'8 o
X
~ 1 X 80
"8 ~Co cJ> 0 oO 0 Oo 0 ~
t
: t .-• • t
• •• • • • •
30 • I 40 I so 60 • I 70 I 80 :I • I . • .. • .. ! ..
Bank Failure Risk
(<10% Risk)
(>10% Risk)
<10% Risk
<10% Risk
1>Ri of
)
7.6
4.7
3.7
2.1
1.5
1.1
0.85
0.66
0.52
0.34
Bank height and angle
schematic
Form 6 Figure 1. Probability Mass Wasting diagram, Bank Angle:Height/% Risk table, and
Band Height:Angle schematic.
Probability is less than 10% for the existing bank angles (2:1 = 26.6 degrees) in Reaches 1 -5.
(Sheet 1 of 1)
REACH 1 THROUGH 4 RESULTS
B -12
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ResultV-aew CRITICAL STRESS CALCULATOR RESULTS FOR REACH 1
Define Drainage Basins Basin. Unnamed Tributary
POC lJ ----I
Manage Your Point of Compliance (POC)
Analyze the receiving water at the 'Point of Compliance' by completing
this form. Click Edit and enter the appropriate fields, then dick the
Update button to calculate the critical flow and low-flow threshold
condition. Finally, click Save to commit the changes. [
Channel Susceptibility:
Low Flow Threshold: .,.!i_5Q2 ___ _.._..,.4:[
55-i:Hil Ef 11¥ Adi
Channel Assessed: j ves
Watershed Area (ac}: 1267.8-4
Material: !vegetation
Roughness: lo.100
Channel Top Width (ft): lao.o
Channel Bottom Width (ft): 120.0
Channel Height {ft): 110.0
Channel Slope: jo.0181
B Vertical I . Susceptibility: Low (Vertical)
Lateral Susceptibility: I Low (Lateral)
l...lrgeView
El
3
a
ProJect La Costa Valley School Site Development
J------------------0 ----
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Define Drainage Basins Basin. Unnamed Tributary ProJect La Costa Valley School Site Development
_J u POC u~lF~'.J--J_ _________ _
Manage Your Point of Compliance (POC)
Analyze ttle receiving water at lhe 'Point of Compliance· by completing
tflis form. Click Edit and enter the appropriate fields, then elide the
Update button to calcu.late the affical flow and low-flow threshold
condition. Finally, click Save to commit the changes.
lii:IH• Miki Adi
El
Channel Susc.eptibility:
Low Flow Threshold:
Vertical I . Susceptibility: Low (Ve.rtical) Channel Assessed: Ives
Watershed Area (ac): 1329.25 Lateral Susceptibility: I Low (Lateral)
Material: !vegetation
Roughness: lo.100
Channel Top Width (ft): 1100.0
Channel Bottom Width (ft): 140.0
Channel Height (ft): 110.0
Channel Slope: lo.0107
G
large View
B
EJ
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CRITICAL STRESS CALCULATOR RESULTS FOR REACH 3
~ Define Drainage Basins Basin. Unnamed Tributary ProJect· La Costa Valley School Site Development
Q_r POC 7......,.1_-~~-__._! ________________ _
Manage Your Point of Compliance (POC)
Analyze the receiving water at the 'Point of Compliance' by completing
this form. Click Ecflt and enter tfle appropriate fields, then click the
Update button to calculate the critical flow and low-flow threshold
condition. Finally, click Save to commit the changes.
Adi
B
l Channel Susceptibility: !Low -~ I
Low FtowThreshold: [o~ ~
Vertical I . Susceptibility: Low (Vertical) Channel Assessed: !Yes
Watershed Area (ac): 1357 .28 Lateral Susceptibility: I Low (Lateral)
B
B
Material: !vegetation
Roughness: (0.100
Channel Top Width (ft}: 1100.0
Channel Bottom Width (ft}: 140.0
Channel Height (ft): j10.o
Channel Slope: jo.01411 X
l..asge~
G
--0 ~ n. ------------...---
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M Define Drainage Basins Basin: Unnamed Tributary
poc l l -I
Manage Your Point of compliance (POC)
Analyze the receiving water at the 'Point of Compliance' by completing
th.is form. Click Edit and enter the appropriate fields, then click the
Update button to calculate the critical flow and low-flow threshold
condition. Finally, click Save to commit the changes.
jChannel Susceptibility: ..--------, L Low Flow Threshold:
Ffm@f WMI
Channel Assessed: Ives
Watershed Area (ac): 1419.35
Material: !vegetation
Roughness: jo.100
Channel Top Width (ft): 190.0
Channel Bottom Width (ft): lso.o
Channel Height (ft): ls.o
Channel Slope: lo.0043
B Vertical I . Susceptibility: Low (VertJcal)
Lateral Susceptibility: I Low (Lateral)
large View
G
El
El
Project: La Costa Valley School Site Development
2-&·xs· RCS AT CALLE
BARCELONA AND EL
CAMINO REAL
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AEFDIOIC( QTY OF CMlS8AD D'IIC.
NO. 322--!A
Project Design~
701 'II' S'h'Nf:, .SUU. IIOO. S•11 Owp. C.c IZIOt ..,._,..,_..,,,,u°'~
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BENCHMARK: ~ EltCINWIINC llD'ARTMENT .39
l.OCA TlON: El. CAialO REAL GltAlllNG NII[) EJI090N C0NTIIOl Pl.ANS f'0lt:
OE$CR!P110H: ~~-cx:::o ARROYO LA COSTA
CENTER!H IIONIJMEIH
W:VATlON: 79.716 FU:T u.s.c.s. CT 88-~2 UNIT 2
11.S.L DATUM
A£fEJllllCE:
COUNTY OF SAH DIEGO
9EIIC!illARIC 8001< PAGE: 1&4, DATE: APRll 19811
CON1l!Ol P091T DESICHATlON: e1+n INT.
CAL COORDIIIAlE N)(X 116-4252 _(HAD 83)
~I I I I ~ I II~~ -12->l ... 71 I--+--+---------:-+--+--•+---+-~-~ 11-Z-{jlt-. Def INITIAL DAlENTI; DATENTIAL D~ BY: ,D~ I PROJECT NO. 11 DIIA-NO.
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S1CAI.E: HOAIZ: ,·-40': 't(JIT: , ....
11
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AVENIDA HELECHO
Project Design Consultants
701 a• .$"t,w1;, Svia• IJOO, Son DWf10. CA 1%101 .,.......,,., ,u -,-osn -ft
s, ;;;iJc
"f 0 -40 110 PRIVA lI: CONlRACT ~ -DATE
BENCHMARK: ~ -I ~ 11 CITY Of' CARLSBAD I ISHmS I ENGINEERING 0£1'ARlllENT 39
LOCATial: £1.CAMNOREAL AHO OU-ROAi> GIIAl»IG ~ EIIOSl0II CONTRQ. Pl.ANS FOR:
~"=~~\O ARROYO LA COST A DESCl!PllON:
ruYAllON: ~~;{~' lJr,..u.s.c.s. CT 88-03-2 UNIT 2 !~ ~iv;-•' I REraEIC£:
COUHTY OF SAN DIEGO IIE)jQIMARK BOOK
PAC£ 164, OATE: APRll 19811
CONTRQ. POINT OESIGNATlON: 81+ 72 INT.
C/ll. ~IE NO I~ OIAI> SJ'.
REVISION DESCRIPTION
_,..,. UA I I ....,,.,._,_ ~--•
11
UKA'MNC NO.
325-1A
J.M. a,0.1 I
ATTACHMENT 3
Structural BMP Maintenance Information
Use this checklist to ensure the required information has been included in the Structural
BMP Maintenance Information Attachment:
Preliminary Design/Planning/CEQA level submittal:
Attachment 3 must identify:
181 Typical maintenance indicators and actions for proposed structural BMP(s)
based on Section 7. 7 of the BMP Design Manual
Final Design level submittal:
Attachment 3 must identify:
J Specific maintenance indicators and actions for proposed structural BMP(s). This
shall be based on Section 7. 7 of the BMP Design Manual and enhanced to reflect
actual proposed components of the structural BMP(s)
How to access the structural BMP(s) to inspect and perform maintenance
Features that are provided to facilitate inspection (e.g., observation ports,
cleanouts, silt posts, or other features that allow the inspector to view necessary
components of the structural BMP and compare to maintenance thresholds)
J Manufacturer and part number for proprietary parts of structural BMP(s) when
applicable
Maintenance thresholds for BMPs subject to siltation or heavy trash(e.g., silt level
posts or other markings shall be included in all BMP components that will trap and
store sediment, trash, and/or debris, so that the inspector may determine how full
the BMP is, and the maintenance personnel may determine where the bottom of
the BMP is . If required, posts or other markings shall be indicated and described
on structural BMP plans.)
Recommended equipment to perform maintenance
When applicable, necessary special training or certification requirements for
inspection and maintenance personnel such as confined space entry or
hazardous waste management
25
APPENDIX 3 -BMP MAINTENANCE PLAN BIOFILTRA TION PLANTER
MAINTENANCE PLAN FOR BIOFILTRATION PLANTER
1. INSPECTION FREQUENCY
Inspections of the Biofiltration Planters will occur at a minimum per ta ble A.1-10 in
appendix A of the San Diego County LID Handbook 2014 (see below).
Table A.1·10. lnspettion and maintenance tasks
Indicator maintenance is
Task Frequency needed Maintenance notes
Catchment Weekty-or brweekly with Excessive sediment, trash, or Permanently stabilize any
inspection routine property debris accumulation on the exposed soil and remCNe any
maintenance surface of bioretention accumulated sediment. Adjacent
pervious areas might need to be
r&graded.
Inlet inspection Weekty-or brweekly with Internal erosion or excessive Check for sediment accumulation
routine property sediment, trash, and debris to ensure that flow into the
maintenance accumulation bioretention is as designed.
Remove any accumulated
sediment.
Trash and leaf Weekty-or brweekly with Accumulation of litter and leafy Utt er and leaves should be
litter re mova I routine property debris within bioretention area remCNed to reduce the risk of
maintenance outlet clogging, reduce nutrient
inputs to the bioretention area,
and to improve facility aesthetics.
Pruning One to two times per Overgrown vegetation that Nutrients in runoff often cause
year interferes with access, lines of bioretention vegetation to flourish.
sight, or safety
Mowing two to twelve times per Overgrown vegetation that Frequency depends on location
year interferes with access, lines of and desired aesthetic appeal.
sight, or safety
Mulch removal One time every 2 to 3 213 of mulch has decomposed Mulch accumulation reduces
and replacement years available surface water storage
volume. Removal of decomposed
mulch also increases surface
infiltration rate of fill soil. RemCNe
decomposed fraction and top off
with fresh mulch to a total depth of
3 inches
Temporary One time every 2 to 3 Until established and during Watering after the initial year
watering days for first 1 to 2 severe droughts might be required.
months, sporadically
after established
Fertilization One time inltialty-Upon planting One-time spot fertilization for first
year of vegetation.
Remove and One time per year Dead plants Within the first year, 1 O percent of
replace dead plants can die. Survival rates
plants increase Vvith time.
Outlet inspection Once after first rain oft he Erosion at outlet Remove any accumulated mulch
season, then monthly or sediment Ensure IMP
during the rainy season maintains a drain-down time of
less than 72 hours.
Miscellaneous Twelve times per year Tasks include trash collection, plant health, spot weeding, removing
upkeep invasive species, and removing mulch from the overflow device.
Page 1 of 6
FUSCOE ENGINEERING, SAN DIEGO
6390 Greenwich Drive, Suite 170, Son Diego, CA 92122
APPENDIX 3 -BMP MAINTENANCE PLAN BIOFILTRATION PLANTER
2. PREVENTATIVE ACTIONS
The following is a list of actions that will help prevent problems from occurring. They
should be done on a routine basis throughout the duration of the project.
VEGETATION CONTROL
Vegetation in the basin should be trimmed and mowed to keep a maximum height of
18 inches. All vegetation clippings should be removed from the basin when trimming
and mowing is conducted. Trimming and mowing prevents marsh vegetation from
overtaking the basin and creating faunal habitats. It also prevents areas of water
stagnation which con create a vector and health problem.
BIOFILTRATION PLANTER CLEANING
Trash and debris should be removed from the planter. Special attention should be
given to the inlet and outlet structures. A build up of trash and debris in these areas
con decrease the efficiency of the basin or make it inoperable during storms.
VECTOR CONTROL
Sediments deposited at the inlet structures should be managed to prevent areas of
ponding and possible vector problems. Sediment grading con be accomplished by
manually raking the deposits.
FILTER MEDIA AND SEDIMENT REMOVAL
The planter shall be excavated and cleaned, and grovel or soil shall be replaced to
correct low infiltration rotes. Holes that ore not consistent with the design and allow
water to fl ow directly through the planter to the ground shall be plugged. Sediment
accumulation shall be hand removed with minimum damage to vegetation using
proper erosion control measures. Sediment shall be removed if it is more than 2
inches thick or so thick as to damage or kill vegetation.
EQUIPMENT INSPECTION
All physical components of the Biofiltrotion Planter should be regularly inspected for
operability.
GENERAL CLEANUP
Weeds will be removed around fences and gross trimmed. All landscape clippings
and cleaning solvents used to remove graffiti should be properly removed from the
planter ofter cleanup.
Page 2 of 6
FUSCOE ENGINEERING, SAN DIEGO
6390 Greenwich Drive, Suite 170, Son Diego, CA 92122
APPENDIX 3 -BMP MAINTENANCE PLAN BIOFILTRATION PLANTER
3. MAINTENANCE INDICATORS AND CORRECTIVE ACTIONS
The following is a list of indicators that would trigger immediate corrective actions to
be taken. Corrective action should be taken within l O days to ensure that damage
does not occur from the Biofiltration Planter not operating efficiently.
BLOCKAGE O F INLETS/OUTLETS
Any blockages from sediment, debris, or vegetation that keep the Biofiltration
Planter from operating effectively will be removed immediately and properly
disposed of. The Biofiltration Planter should be able to completely drain
within 3-4 hours of a storm event.
STRUCTURAL DAMAGE
If any damage to the structural components of the Biofiltration Planter is
found, repairs will be made promptly. Designers and contractors will conduct
repairs where structural damage has occurred.
EMBANKMENT DAMAGE
Any damage to the embankments and slopes will be repaired quickly so that no
erosion will occur.
EROSION DAMAGE
If there is damage due to erosion such as siltation, steps will be taken to prevent
further loss of soil and repair any conditions that may cause the Biofiltration Planter to
not operate effectively. Possible corrective steps include erosion control blankets,
riprap, sodding, or reduced flow through the area. Design engineers will be consulted
to address erosion problems if the solution is not evident.
FENCE DAMAGE
Timely repair of fences will be done to maintain the security of the site and
the safety of residents.
INVASIVE VEGETATION
If necessary, elimination of trees and woody vegetation will be required.
Woody vegetation will be removed from embankments.
ANIMAL BURROWS
Animal burrows will be filled and compacted. Further steps may be needed
to physically remove the animals if the problem persists. Vector control
specialists will be consulted regarding possible solutions. Th is consulting is
necessary as the threat of rabies in some areas may necessitate the animals
being destroyed rather than relocated.
Page 3 of 6
FUSCOE ENGINEERING, SAN DIEGO
6390 Greenwich Drive, Suite 170, Son Diego, CA 92122
APPENDIX 3 -BMP MAINTENANCE PlAN BIOFILTRATION PlANTER
EQUIPMENT DAMAGE
General corrective maintenance will be done to fix any damage done to the
Biofiltration Planter or related components. If corrective maintenance is being done to
one component, other components will be inspected to see if ma intenance is needed.
4. PROPOSED METHOD OF DISPOSING OF SEDIMENT AND
POLLUTANTS
Removed sediment materials are not considered hazardous waste and can be
disposed of as landscaping material. If it is determined that hazardous waste has been
deposited into the Biofiltration Planter, the suspected waste will be analyzed to
determine proper disposal options.
Page 4 of 6
FUSCOE ENGINEERING, SAN DIEGO
6390 Greenwich Drive, Suite 170, San Diego, CA 92122
APPENDIX 3 -BMP MAINTENANCE PLAN BIOFILTRATION PLANTER
Inspected By: ________ _ Inspection Date: --------
Biofiltration Planter Location/ID: --------
MAINTENANCE ACTIVITY CHECKLIST
D Has trash and debris been removed from the Biofiltration Planter?
D Has the outlet been inspected and debris and sediment removed from it?
D Is the sediment 2" deep? If so, have the accumulated materials been
removed?
D Is Vegetation in the basin taller than 18 inches? If so, was it trimmed and
mowed?
D Were the banks of the basin inspected for vegetative stabilization?
D Do the banks need replanting?
D Are there signs of severe erosion in the form of ruts or sediment deposits?
D Have the banks been inspected for structural integrity?
D Have the fences been inspected?
D Is there graffiti? Has it been removed?
D Has the grass been trimmed around fences, the basin, outlet structures, and
sampling structures?
D Have weeds been removed?
D Have alluvial deposits created zones of ponded water? If so, were the
sediments manually raked to eliminate the ponding zones?
D Have all the valves, fence gates, locks, and access hatches been inspected?
0 Are there any trees or woody vegetation on the embankments? Hove they
been removed?
D Are there any animal burrows? Were they filled and compacted?
D Does the Biofiltration Planter completely within 3-4 hours of the storm event? If
not was the soil/filter medium replaced o r amended to allow the basin to drain within
3-4 hours?
Page 5 of 6
FUSCOE ENGINEERING, SAN DIEGO
6390 Greenwich Drive, Suite 170, Son Diego, CA 92122
APPENDIX 3 -BMP MAINTENANCE PLAN BIOFILTRATION PLANTER
Items Repaired or Replaced
Page 6 of 6
FUSCOE ENGINEERING, SAN DIEGO
6390 Greenwich Drive, Suite 170, Son Diego, CA 92 122
ATTACHMENT 4
City standard Single Sheet BMP (SSBMP) Exhibit
[Use the City's standard Single Sheet BMP Plan.]
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PARTY l£SPONSl!l£ FOIi MAH113W1Ce
NAM£: COA5n.JN£ COUMVMTY CHVROI
A/JOR[SS 2215 CALLE BARCflONA
C,TY, STA Tf CARLSBAD CA 92009
Tf1£PHON[, 760-75J 0886
CONTACT NAM£
PLAN PIEPAIE> BY,
FIRM: FUSCO£ ENGINE£RINC
ADDRfSS: 6J.9Q GRffN\MCH QR/~ SU/1£ 170
CJTY. STA Tf· $AN Ql[GO CALlfORNIA 92122
TfLEPHONf. (858) 554-150() DATE· ______ _
BY. -----("£~R,~c~,~R~11s~1R~ON=G~)-----
R,C,[ NO,,~J6=08~J~-----------
REGISTRATION fXPIRATION OATf-Q§-JQ-2020
BlrNOTBI
1 THESE BMPS ARE MANDATORY TO BE INSTALl.£0 PER MANUFACTURER'S
RECOMMENDATIONS OR THESE PLANS,
2. NO CHANGES TO THE PROPOSED BMPS ON THIS SHEET WITHOlJT PRIOR APPROVAL FROM THE CITY ENGINEER.
3. NO SUBSTITlJTIONS TO THE MATERIAL OR n'PES OR PLANTING TYPES
WITHOUT PRIOR APPROVAL FROM THE CITY ENGINEER
4. NO OCCUPANCY WIU BE GRANTED UNTIL THE CITY INSPECTION STAF'F
HAS INSPECTED THIS PRO.JECT FOR APPROPRIATE BMP CONSTRUCTION AND INSTAUATION.
5. REFER TO MAINTENANCE AGREEMENT DOCUMENT. 6. SEE PRO.JECT SWMP FOR ADDmONAL INFORMATION.
BMP TABLE
IDH \ BMP TYPE \ SYMBOL \CASQA #\ QUANTITY \ DRAWING NO.
HYDROMODIF!CATION & POLLUTANT CONTROL
CD BIOFILTRATIO, TC-32 2875 SF A'-Oll2018--0003 AREA ......
0 BIOFILTIRATIO, TC-32 240 SF AMDD2018-0003 AREA ......
Q) BIOFILTRATIO, TC-32 915 SF A'-Oll20 ! B--0003 AREA ......
SOURCE CONTROL
0 I INLET STENC~ S0-13 I 9 EA I A'-Oll2018--0003 I
COASTLINE COMMUNITY CHURCH
BMP EXHIBIT
NOTES:
LEGEND
PROJECT BOUNDARY
PROPCSED CONTOUR w.JOR
PROPOSED CONTOUR MINOR
EXISTING STORM DRAN
PROPOSED PAVING
PROPOSED RETAINING WAU
BIOFlLIRATION BASIN
~"":~·~ r········
BMP-1, BMP-2, AND BMP-3 SHALL HAVE
VEGETATIVE COVER OF AT LEAST 75%.
BMP MAINTENANCE SHALL BE ONCE EVERY 10
YEARS.
SHEET(S) NO.
Cl .O-C2.2 QUARTERLY SEIi I -AfNJAU. Y IX PER 10 YEARS
Cl .0-C2.2 OUARTERL.Y SEMI -»KJALL Y 1X PER 10 YEARS
c, O-C2.2 WARTERLY-SEMI-At,NJAl..l..Y 1X PER 10 YEARS
c, .O-C2 2 OUARTERL Y I OUARTERL Y
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SCALE I. • 50'
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6390 Greenwich Df • Sui,. 170, Son Diego, Colitomio 92122 ~
tel 858 S5-4 1500 • fax858 597 0335 o ...,_~•com I L_ _____________________________________________________________________ ____, t