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Home My WebLink About2017-09-20; Planning Commission; ; SUP 06-10X2(A) (DEV06068) – AGUA HEDIONDA OUTER LAGOON MAINTENANCEThe City of CARLSBAD Planning Division A REPORT TO THE PLANNING COMMISSION Item No. Application complete date: August 1, 2016 P.C. AGENDA OF:September 20, 2017 Project Planner: Pam Drew Project Engineer: Jason Geldert SUBJECT: SUP 06-10X2(A) (DEV06068) – AGUA HEDIONDA OUTER LAGOON MAINTENANCE – Request for approval for a retroactive five year extension and amendment of a Floodplain Special Use Permit to allow for periodic maintenance dredging of the Agua Hedionda Outer Lagoon (that portion of the lagoon adjacent to the ocean between Carlsbad Boulevard and the railroad track trestles), and the placement and quantities of the dredged sand, as suitable, to the north and south of the inlet jetty within the Agua Hedionda Segment of the city’s Local Coastal Program, where the California Coastal Commission (CCC) has retained coastal development permitting authority. The sand dredge and receiver sites are located in the city’s Local Facilities Management Zone 1. The City Planner has determined that the project belongs to a class of projects that the State Secretary for Resources has found do not have a significant impact on the environment, and it is therefore categorically exempt from the requirement for the preparation of environmental documents pursuant to Section 15304(g), which specifically exempts maintenance dredging where the spoil is deposited in a spoil area authorized by all applicable state and federal regulatory agencies of the state CEQA Guidelines. I.RECOMMENDATION That the Planning Commission ADOPT Planning Commission Resolution No. 7265 APPROVING a retroactive five year extension from October 18, 2016, through October 18, 2021, and amendment of Special Use Permit SUP 06-10X2(A) based upon the findings and subject to the conditions contained therein. II.BACKGROUND AND DISCUSSION The Planning Commission conducted a public hearing to consider the above-referenced Special Use Permit (SUP) application on September 6, 2017. Members of the public raised concerns that sediments proposed to be dredged from the outer lagoon could potentially contain toxic contaminants. Speakers requested that the Planning Commission add a permit condition to require sediment toxicity testing prior to placement of dredged materials on the beach. After some questions and discussion regarding whether the city or another regulatory agency had the appropriate jurisdiction to require such testing, the Planning Commission voted to continue this item to their September 20, 2017 meeting in order to allow staff and the applicant additional time to gather information to confirm actual sediment toxicity testing requirements. In addition to the city-issued SUP, Cabrillo is subject to separate permits from five state and federal agencies in order to conduct dredging operations: U.S. Army Corps of Engineers (USACE), California Coastal Commission, San Diego Regional Water Quality Control Board (RWQCB), California Department of Parks and Recreation, and State Lands Commission (see Attachment 4 for more details). Among these agency permits, the USACE requires sampling and analysis of sediment prior to each dredge cycle, in coordination with the Environmental Protection Agency (EPA). The testing evaluates grain size and sand 1 SUP 0610X2(A) (DEV 06068) – AGUA HEDIONDA OUTER LAGOON MAINTENANCE September 20, 2017 Page 2 chemistry (see Condition Nos. 5 and 17 in Attachment 3). According to the USACE, additional chemical testing is only required if a chemical exceeds the upper limit of their parameters (see Attachment 4). No prior chemical testing of the outer lagoon has ever exceeded the upper limits. The RWQCB requires weekly total coliform testing during sediment discharge operations. Should there be an exceedance of coliform levels, daily monitoring would then be required and the County Department of Environmental Health would be notified for potential beach closure (Attachment 4). Information provided by NRG, USACE and RWQCB confirms that previously required sediment testing of dredge material from the outer lagoon revealed that “there were very few chemicals of concern detected within the collected sediments; and when detected, concentrations were at low levels, and if available, below established effects range low (ERL) guideline values (see Attachment 4, Sediment Characterization Report, July 2014, p.1).” Given previous conclusions that dredge materials have not had toxic contaminants of concern, and that current USACE permit conditions will require sediment toxicity testing for future dredging operations, staff concludes that a city SUP condition for such testing is unnecessary, and therefore recommends approval of the SUP permit as conditioned in Resolution No. 7265. ATTACHMENTS: 1. Planning Commission Resolution No. 7265 2. Planning Commission Staff Report dated September 6, 2017 without Resolution 3. Department of the Army Permit No. SPL-2001-00328-RRS 4. Correspondence from NRG dated September 12, 2017 5. Correspondence from USACE and RWQCB The City of CARLSBAD Planning Division A REPORT TO THE PLANNING COMMISSION Item No. Application complete date: August 1, 2016 P.C. AGENDA OF:September 6, 2017 Project Planner: Pam Drew Project Engineer: Jason Geldert SUBJECT: SUP 06-10X2(A) (DEV06068) – AGUA HEDIONDA OUTER LAGOON MAINTENANCE – Request for approval for a retroactive five year extension and amendment of a Floodplain Special Use Permit to allow for periodic maintenance dredging of the Agua Hedionda Outer Lagoon (that portion of the lagoon adjacent to the ocean between Carlsbad Boulevard and the railroad track trestles), and the placement and quantities of the dredged sand, as suitable, to the north and south of the inlet jetty within the Agua Hedionda Segment of the city’s Local Coastal Program, where the California Coastal Commission (CCC) has retained coastal development permitting authority. The sand dredge and receiver sites are located in the city’s Local Facilities Management Zone 1. The City Planner has determined that the project belongs to a class of projects that the State Secretary for Resources has found do not have a significant impact on the environment, and it is therefore categorically exempt from the requirement for the preparation of environmental documents pursuant to Section 15304(g), which specifically exempts maintenance dredging where the spoil is deposited in a spoil area authorized by all applicable state and federal regulatory agencies of the state CEQA Guidelines. I.RECOMMENDATION That the Planning Commission ADOPT Planning Commission Resolution No. 7265 APPROVING a retroactive five year extension from October 18, 2016, through October 18, 2021, and amendment of Special Use Permit SUP 06-10X2(A) based upon the findings and subject to the conditions contained therein. II.BACKGROUND AND PROJECT DESCRIPTION Background Dredging operations in the lagoon have been conducted routinely since 1954 – the year SDG&E removed 4,279,000 cubic yards of material from the lagoon, opened the lagoon mouth to a continuous tidal flow and constructed the Encina Power Station. The dredging is performed to remove sediment transported into the lagoon through the existing inlet jetty. The removal of sediment allows a higher volume of water in the lagoon to provide the Encina Power Station with an adequate volume of seawater for cooling purposes and for the Claude “Bud” Lewis Carlsbad Desalination Plant intake. Dredging of the lagoon has occurred in the past under previously issued city permits (SUP 92-04, SUP 01-02, SUP 06-10 and SUP 06- 10X1). The dredging operation has historically consisted of removing varying amounts of sand from the intake channel and the outer lagoon, performed at varying frequencies, and the placement of dredged sand on the beach to the north and south of the inlet. The last dredging of the outer lagoon was completed in April 2015, which resulted in the removal of 294,661 cubic yards of sand. 5 ATTACHMENT 2 SUP 0610X2(A) (DEV 06068) – AGUA HEDIONDA OUTER LAGOON MAINTENANCE September 6, 2017 Page 2 The city has conditionally approved previous dredging projects consisting of the placement of sand on the City of Carlsbad’s beaches in a manner consistent with the recommendations of a study regarding beach sand transport. The report, entitled “Study of Sediment Transport Conditions in the Vicinity of the Agua Hedionda Lagoon” (October 1999), was prepared by an independent coastal engineer in response to a prior CCC requirement of the Encina Power Station owner. The study looked at average historical sedimentation rates and conditions in and around the lagoon and the adjacent beaches. The 1999 study recommended, based on a variety of scientific and public benefit considerations, that 30% of the dredged sand be placed on north beach (between the inlet jetty and Oak Avenue to the north); and the remaining 70% be divided between middle beach (between the inlet and discharge jetties) and south beach (extending 1,600 feet south from the discharge jetty). With the SUP permit extension, the applicant has requested a condition amendment to remove the strict 30%/70% sand placement in favor of a more flexible distribution based on the carrying capacity of north beach. The applicant has asserted that placing more sand in excess of the beach’s capacity near the inlet jetty results in rapid sand loss back into the lagoon in a short period of time. After initial review of the application, staff requested an updated technical report to support the proposed condition amendment. In mid-June 2017, the applicant provided the city with an analysis by Dr. Scott A. Jenkins, Ph.D. titled, “Beach Equilibrium Analysis of North Beach Disposal Options for Dredged Sands from Agua Hedionda Lagoon, Carlsbad, CA, revised June 15, 2017” (Attachment 7). The primary objective of the report was to utilize the latest coastal science to determine the optimal beach fill templates (volume and profile shape) that would maximize the retention time of sand placed on north beach. According to the author, the study focused on the disposal area between the north inlet jetty and Maple Avenue because: 1) sand loss rates are less along this section because the wave cut platform in the bedrock is wider and can hold more sand volume than the sections of north beach further to the north of Maple Avenue; 2) the southern end of north beach is stabilized by the north inlet jetty, which also functions as a "beach groin" shore protection structure. Consequently sand placed in the southern reach of north beach is a longer lasting investment than further north between Cherry and Oak Avenues; 3) more beach visitors and recreational beach use occurs along the southern end of north beach; and 4) there is more beach profile data and more scientific information about the southern end of north beach as compared to the areas further north. The entire Agua Hedionda Lagoon is located within the Agua Hedionda Segment of the city’s Local Coastal Program, where the CCC has retained coastal development permitting authority. That dredging activity was authorized by the CCC in October of 2014 under CDP 6-14-1128. Each dredging cycle requires a new CDP issued by the CCC, once local permits have been secured (i.e., this SUP extension and amendment request). Project Description Cabrillo Power I LLC (Cabrillo), filed for an application requesting a retroactive five year extension and amendment to Floodplain Special Use Permit (SUP 06-10X1) to allow for the continued: 1) periodic maintenance dredging of up to 500,000 cubic yards in any single event at the Agua Hedionda Outer Lagoon, and 2) placement of the dredged sand on Carlsbad beaches. The outer lagoon is that portion of the lagoon adjacent to the ocean between Carlsbad Boulevard and the railroad track trestles, including the ocean water intake channel between the northerly set of jetties. The periodic dredging is necessary to prevent the closure of the lagoon inlet and to ensure that an adequate supply of cooling ocean water is available for the operation of the Encina Power Station and for the Claude "Bud" Lewis Carlsbad Desalination Plant. SUP 0610X2(A) (DEV 06068) – AGUA HEDIONDA OUTER LAGOON MAINTENANCE September 6, 2017 Page 3 This permit would authorize Cabrillo to periodically dredge the lagoon through October 18, 2021. NRG (Carlsbad Energy Center LLC) has started construction of a “peaker” style power plant which is expected to be completed by the end of 2018. The EPS, which relies on the use of ocean water for once-through cooling, is currently scheduled for shutdown by the end of 2017. However, the California Independent System Operator (CaISO), through the Statewide Advisory Committee on Cooling Water Intake Structures (SACCWIS), has requested the State Water Resources Control Board to extend once-through-cooling through the end of 20181. City staff understands that, post-EPS shutdown, dredging responsibility will remain with Cabrillo according to terms of the current lease agreement between Cabrillo and Poseidon Resources. Nourishment projects are designed and constructed to take advantage of natural forces such as waves and currents to move sand offshore. This process is referred to as profile equilibration. This process typically occurs within 12 months following sand replacement (depending on storms). The width of the dry beach above the mean high tide line directly after sand nourishment, appears wider, but is perceived as narrower after a storm event. The sand is redistributed by the current, into the inner and outer surf zones during this natural process. Conventional construction equipment cannot physically place sand below the mean high tide line during the beach nourishment process. As the newly dredged sand is redistributed by the current and waves, it naturally softens the slope of the wet beach, and moves it offshore to fill the deeper parts of the beach profile. The dredged material (slurry) would be pumped through a floating pipeline. For delivery of dredged material to the north beach, the pipe would float on the lagoon, under the Carlsbad Boulevard Bridge, and would connect to above ground, temporary pipes, which would be placed along the beach. For middle and south beach disposal, the slurry would be pumped via a pipe that would float on the outer lagoon and connect to an existing underground pipe under Carlsbad Boulevard located mid-way between the intake and discharge jetties. The pipe would be extended along the surface of Carlsbad State Beach to reach the south side of the Encina Power Station discharge jetty. Temporary dikes and berms would be used to dewater the slurry. Bulldozers and front-end loaders would then be used to spread the sand on the beaches. Equipment and material staging would occur on the north and west shores of the outer lagoon along the shore. North beach (south of Maple Avenue) is very narrow with numerous rocky areas in both the surf zone and where the ocean meets the sand region. These features indicate that this segment of north beach is not well suited to retain large volumes of sand, and will never naturally be a wide flat beach. The narrow horizontal base for beach on North Beach leaves only a limited space on which a beach can be built. Thus, North Beach has a limited carrying capacity for retaining sand from the dredging of the lagoon, and attempts to place more sand on this beach than it can physically hold are not beneficial. Furthermore, putting large amounts of sand or more sand than North Beach is capable of naturally holding can create a “cliff” on the beach due to wave erosion, which makes it unsafe for beach goers and impairs lifeguards’ view of the beach. According to Dr. Jenkin’s report (2017), the North Beach area between the north jetty and Maple Street, has a sand carrying capacity of 79,471 cubic yards. Accordingly, staff recommends that a permit condition be added requiring applicant to submit for the Parks and Recreation Director review a sand deposition plan detailing the cubic yards of sand to be dredged from the outer lagoon and the justification for the 1The State Water Resources Control Board approved the “Proposed Amendment to the Water Quality Control Policy on the use of Coastal and Estuarine Water for Power Plant Cooling – Encina Power Station” at the August 15 Board meeting. SUP 0610X2(A) (DEV 06068) – AGUA HEDIONDA OUTER LAGOON MAINTENANCE September 6, 2017 Page 4 quantities of sand to be placed on the north, middle and south beach segments. For the north beach area between the north inlet jetty and Maple Avenue, the amount of sand to be placed will be determined by calculating the difference between the in-place sand volume and the beach’s optimal sand carrying capacity. The carrying capacity of the beach segment between Maple Avenue and Pine Avenue will be calculated and submitted with the sand deposition plan. The amount of sand to be placed in the Maple Avenue to Pine Avenue segment will be determined by calculating the difference between the in-place sand volume and this segment’s optimal sand carrying capacity consistent with the methodology described in the Jenkins report (2017). The remaining dredged sand will be placed on middle and south beach segments based upon the sand deposition plan and in consideration of the actual condition of the respective beach segments, public benefits, and public safety. Staff also recommends adding a condition to ensure that berming of sand (a back beach dune to hold and release residual sand as the beach profile adjusts to changing wave climate) provide for an adequate path of travel for the beach-going public and safety personnel, be groomed to provide towel space, and be limited to six feet in height for visibility and safety purposes. The next dredging would occur between January 2, 2018 and April 14, 2018, before the beginning of the summer season, consistent with previous permits. III. ANALYSIS This project is subject to the following plans and regulations: 1. General Plan Goals and Policies; 2. Open Space Zone (Chapter 21.33); 3. Floodplain Management Regulations (Chapter 21.110) and Special Use Permit Procedures (Section 21.110.130); and 4. Local Coastal Program and Coastal Resource Protection Overlay Zone (Chapter 21.203). Staff developed its approval recommendation after analyzing the project’s consistency with the applicable city plans and regulations listed above. A discussion on compliance with each follows. The adopted project findings for SUP 06-10, which are contained in Planning Commission Resolution No. 6181, and SUP 06-10X1, which are contained in Planning Commission Resolution No. 6904 are superseded by the following findings: A. City of Carlsbad General Plan 1. The project is consistent with the Open Space, Conservation, and Recreation Element Goals 4-G.5 and 4-G.9 of the General Plan in that the placement of dredged sand on the beach will enhance public recreation opportunities by maintaining or increasing the size (i.e., square footage area) of useable public beach. 2. The project is consistent with the Open Space, Conservation, and Recreation Element Policy 4- P.33 of the General Plan in that dredging the outer lagoon and the intake channel, in particular, will allow for the continued flow of fresh, nutrient-rich ocean waters into the lagoon, thereby maintaining/improving the overall health of the lagoon. SUP 0610X2(A) (DEV 06068) – AGUA HEDIONDA OUTER LAGOON MAINTENANCE September 6, 2017 Page 5 3. The project is consistent with the Public Safety Element Goal 6-G.1 and Policy 6-P.2 of the General Plan in that the placement of dredged sand on the beach will enhance and protect important city open space resources by assisting the buildup of a deteriorating beach profile and by creating a wider beach which will assist in the protection of coastal bluffs from erosion caused by ocean wave action, thereby protecting private and public property in the vicinity of the beach. B. Open Space Zone 1. The project is an allowable activity/use in the Open Space Zone and complies with all its standards in that the dredge activity and placement of sand on the beach will maintain/improve the overall health of the lagoon by a) dredging the intake channel and ensuring the continued flow of fresh, nutrient-rich ocean waters into the lagoon; and b) enhancing the quality of the beach by placing dredged sand on the beach, thereby assisting in the buildup of a deteriorating beach profile. C. Floodplain Management Regulations and Special Use Permit Procedures 1. The proposed lagoon dredge will not create a hazard or adversely impact development, or adjacent and upstream properties and structures; and the cumulative effect of this project and the adjacent approved projects will not significantly raise the level of the 100-year floodplain (base flood elevation) in that the dredge activity will increase the physical capacity of the lagoon and, therefore, the ability of the lagoon to accommodate flood waters. D. Local Coastal Plan and Coastal Resource Protection Overlay Zone Although the required CDP will be processed through the CCC, staff has analyzed the project for compliance with pertinent regulations. The project complies with the Local Coastal Program and Coastal Resource Protection Overlay Zone requirements as discussed below. 1. The project is in conformance with the Certified Local Coastal Program and all applicable policies in that: a. Dredging the outer lagoon and the intake channel, in particular, will allow for the continued flow of fresh, nutrient-rich ocean waters into the lagoon, thereby maintaining/improving the overall health of the lagoon; and the placement of dredged sand on the beach will enhance and protect coastal resources by assisting the buildup of a deteriorating beach profile and by creating a wider beach, which will assist in the protection of coastal bluffs from erosion caused by ocean wave action. b. The project has been conditioned to require pre-construction survey for presence of Caulerpa taxifolia in the project area and, if found, shall be required to isolate, treat, and eliminate the risk of spreading. c. The project has been conditioned to require pre-construction survey for presence of eelgrass in the area, and if found, shall be required to monitor and mitigate for impacts that may occur as a result of the project. SUP 0610X2(A) (DEV 06068) – AGUA HEDIONDA OUTER LAGOON MAINTENANCE September 6, 2017 Page 6 2. The project is in conformity with the public access and recreation policies of Chapter 3 of the Coastal Act in that the placement of dredged sand on the beach will enhance public recreation opportunities by maintaining or increasing the size (square footage area) of useable beach. Dredge operations would not occur during the peak summer season. The adopted project conditions for SUP 06-10, which are contained in Planning Commission Resolution No. 6181, and SUP 06-10X1, which are contained in Planning Commission Resolution No. 6904 are superseded in their entirety by Resolution No. 7265. IV. ENVIRONMENTAL REVIEW Pursuant to Section 15304 of the California Environmental Quality Act (CEQA) Guidelines, the project is categorically exempt from the provisions of CEQA. Section 15304(g) specifically exempts “maintenance dredging where the spoil is deposited in a spoil area authorized by all applicable state and federal regulatory agencies.” A Notice of Exemption will be filed by the City Planner upon project approval. ATTACHMENTS: 1. Planning Commission Resolution No. 7265 2. Location Map 3. Disclosure Form 4. Planning Commission Resolution No. 6181 dated October 18, 2006 5. Planning Commission Resolution No. 6904 dated August 1, 2012 6. Letter from Dr. Scott A. Jenkins, dated June 19, 2017 7. Beach Equilibrium Analysis of North Beach Disposal Options for Dredged Sands from Agua Hedionda Lagoon, Carlsbad, CA, dated revised June 15, 2017 8. Reduced Exhibits 9. Exhibits “A” – “D” dated September 6, 2017 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 A RESOLUTION OF THE PLANNING COMMISSION OF THE CITY OF CARLSBAD, CALIFORNIA, APPROVING A RETROACTIVE FIVE YEAR EXTENSION AND AMENDMENT OF A FLOODPLAIN SPECIAL USE PERMIT TO ALLOW FOR PERIODIC MAINTENANCE DREDGING OF THE AGUA HEDIONDA OUTER LAGOON AND THE PLACEMENT OF DREDGED SAND ON CARLSBAD BEACHES IN LOCAL FACILITIES MANAGEMENT ZONE 1. CASE NAME: AGUA HEDIONDA OUTER LAGOON MAINTENANCE CASE NO: SUP 06-10X2(A) (DEV06068) WHEREAS, Cabrillo Power I, LLC, “Developer/Owner,” has filed a verified application with the City of Carlsbad regarding property described as Portions of Lot “H” of Rancho Agua Hedionda, according to partition Map No. 823, filed in the Office of the County Recorder of San Diego County, November 16, 1896 (APN: 210-010-4500), ("the Property”); and WHEREAS, said verified application constitutes a request for a Floodplain Special Use Permit Extension and Amendment as shown on Exhibits “A” – “D” dated September 6, 2017, on file in the Planning Division, SUP 06-10X2(A) – AGUA HEDIONDA OUTER LAGOON MAINTENANCE, as provided by Chapter 21.110 of the Carlsbad Municipal Code; and WHEREAS, the Planning Commission did on September 6, 2017, hold a duly noticed public hearing as prescribed by law to consider said request; and WHEREAS, at said public hearing, upon hearing and considering all testimony and arguments, if any, of all persons desiring to be heard, said Commission considered all factors relating to the Floodplain Special Use Permit Extension and Amendment. NOW, THEREFORE, BE IT HEREBY RESOLVED by the Planning Commission of the City of Carlsbad as follows: A) That the foregoing recitations are true and correct. B) That based on the evidence presented at the public hearing, the Commission APPROVES SUP 06-10X2(A) – AGUA HEDIONDA OUTER LAGOON MAINTENANCE effective retroactively from October 18, 2016, through October 18, 2021, based on the following findings and subject to the following conditions: PLANNING COMMISSION RESOLUTION NO. 7265 PC RESO NO. 7265 -2- 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 Findings: The adopted project findings for SUP 06-10, which are contained in Planning Commission Resolution No. 6181, and SUP 06-10X1, which are contained in Planning Commission Resolution No. 6904, are superseded by the following findings: 1. The project is consistent with the Open Space, Conservation, and Recreation Element Goals 4-G.5 and 4-G.9 of the General Plan in that the placement of dredged sand on the beach will enhance public recreation opportunities by maintaining or increasing the size (i.e., square footage area) of useable public beach. 2. The project is consistent with the Open Space, Conservation, and Recreation Element Policy 4- P.33 of the General Plan in that dredging the outer lagoon and the intake channel, in particular, will allow for the continued flow of fresh, nutrient-rich ocean waters into the lagoon, thereby maintaining/improving the overall health of the lagoon. 3. The project is consistent with the Public Safety Element Goal 6-G.1 and Policy 6-P.2 of the General Plan in that the placement of dredged sand on the beach will enhance and protect important city open space resources by assisting the buildup of a deteriorating beach profile and by creating a wider beach which will assist in the protection of coastal bluffs from erosion caused by ocean wave action, thereby protecting private and public property in the vicinity of the beach. 4. The project is an allowable activity/use in the Open Space Zone and complies with all its standards in that the dredge activity and placement of sand on the beach will maintain/improve the overall health of the lagoon by a) dredging the intake channel and ensuring the continued flow of fresh, nutrient-rich ocean waters into the lagoon; and b) enhancing the quality of the beach by placing dredged sand on the beach, thereby assisting in the buildup of a deteriorating beach profile. 5. The proposed lagoon dredge will not create a hazard or adversely impact development, or adjacent and upstream properties and structures; and the cumulative effect of this project and the adjacent approved projects will not significantly raise the level of the 100-year floodplain (base flood elevation) in that the dredge activity will increase the physical capacity of the lagoon and, therefore, the ability of the lagoon to accommodate flood waters. 6. The project is in conformance with the Certified Local Coastal Program and all applicable policies in that: a. Dredging the outer lagoon and the intake channel, in particular, will allow for the continued flow of fresh, nutrient-rich ocean waters into the lagoon, thereby maintaining/improving the overall health of the lagoon; and the placement of dredged sand on the beach will enhance and protect coastal resources by assisting the buildup of a deteriorating beach profile and by creating a wider beach, which will assist in the protection of coastal bluffs from erosion caused by ocean wave action. b. The project has been conditioned to require pre-construction survey for presence of Caulerpa taxifolia in the project area and, if found, shall be required to isolate, treat, and eliminate the risk of spreading. c. The project has been conditioned to require pre-construction survey for presence of eelgrass in the area, and if found, shall be required to monitor and mitigate for impacts that may occur as a result of the project. PC RESO NO. 7265 -3- 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 7. The project is in conformity with the public access and recreation policies of Chapter 3 of the Coastal Act in that the placement of dredged sand on the beach will enhance public recreation opportunities by maintaining or increasing the size (square footage area) of useable beach. Conditions: The adopted project conditions for SUP 06-10, which are contained in Planning Commission Resolution No. 6181, and SUP 06-10X1, which are contained in Planning Commission Resolution No. 6904 are superseded in their entirety by the following conditions: 1. If any of the following conditions fail to occur, or if they are, by their terms, to be implemented and maintained over time, if any of such conditions fail to be so implemented and maintained according to their terms, the city shall have the right to revoke or modify all approvals herein granted; deny or further condition issuance of all future building permits; deny, revoke, or further condition all certificates of occupancy issued under the authority of approvals herein granted; record a notice of violation on the property title; institute and prosecute litigation to compel their compliance with said conditions or seek damages for their violation. No vested rights are gained by Developer or a successor in interest by the city’s approval of this Special Use Permit Extension. 2. Developer shall comply with all applicable provisions of federal, state, and local laws and regulations in effect at the time of project commencement. 3. If any condition for construction of any public improvements or facilities, or the payment of any fees in-lieu thereof, imposed by this approval or imposed by law on this Project are challenged, this approval shall be suspended as provided in Government Code Section 66020. If any such condition is determined to be invalid, this approval shall be invalid unless the City Council determines that the project without the condition complies with all requirements of law. 4. Staff is authorized and directed to make, or require Developer to make, all corrections and modifications to the Special Use Permit document(s) necessary to make them internally consistent and in conformity with final action on the project. Development shall occur substantially as shown in the approved Exhibits. Any proposed development, different from this approval, shall require an amendment to this approval. 5. This project shall comply with all conditions and mitigation measures which are required as part of the Zone 1 Local Facilities Management Plan and any amendments made to that Plan prior to any dredging activities. Developer shall also pay any applicable Local Facilities Management Plan fee for Zone 1, pursuant to Chapter 21.90. All such taxes/fees shall be paid prior to any dredging activities. If the taxes/fees are not paid, this approval will not be consistent with the General Plan and shall become void. 6. This Special Use Permit is granted retroactively for a period of 5 years from October 18, 2016, through October 18, 2021. This permit may be revoked at any time after a public hearing, if it is found that the use has a substantial detrimental effect on surrounding land uses and the public’s health and welfare, or the conditions imposed herein have not been met. This permit may be extended for a reasonable period of time not to exceed 5 years upon written application of the permittee made no less than 90 days prior to the expiration date. The Planning Commission may not grant such extension, unless it finds that there are no substantial negative effects on surrounding land uses or the public’s health and welfare. If a substantial negative effect on surrounding land uses or the public’s health and welfare is found, the extension shall be denied or granted with conditions which will eliminate or substantially reduce such effects. There is no limit to the number of extensions the Planning Commission may grant. PC RESO NO. 7265 -4- 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 7. At least three months (3) prior to any dredging activity, the Developer shall provide written notice to the City Engineer of such activity. The request shall include the following: i. The Developer shall provide a brief project description of the proposed dredging activity. The description shall include a schedule identifying the beginning and ending dates of the dredging operation, the hours and days of the week for the dredging activity, the anticipated total dredge quantity, the location and quantity for the deposition of sand, the anticipated beginning dates for the deposition on north, middle, and south beaches, and contact information including phone numbers of personnel responsible for the dredging activity. ii. A sand deposition plan describing the methods and equipment needed to deposit and move the sand on the beach reaches. The plan should include best management practices for the maximum retention of sand material on the beach. This could include such practices as creating a dike parallel to the shoreline to allow the material to fall out of the slurry mix, the methods the construction equipment would be utilized to move the material, and other methods to ensure the maximum amount of sand is placed for beach building. iii. The Developer shall provide the City Engineer a plan for interim pedestrian circulation control, to include public information signage describing the project. 8. To determine the proper amount of sand to be placed on the beach during any maintenance dredging cycle, north, middle and south beach segments shall be surveyed no earlier than 45 days prior to commencement of a dredging cycle. No later than 30 days prior to any dredging activity, Developer shall incorporate the survey results into the sand deposition plan and submit for review to the satisfaction of the city’s Parks and Recreation Director, or designee. The current sand volume shall be calculated from the pre-dredge survey and used to guide distribution of dredged sand among the north, middle and south beaches. The amount of sand to be placed on the north beach segment between the north jetty and Maple Avenue shall be limited to the optimal carrying capacity of 79,471 cubic yards, as calculated in the report entitled “Beach Equilibrium Analysis of North Beach Disposal Options for Dredged Sands from Agua Hedionda Lagoon, Carlsbad, CA, dated June 15, 2017”. If the calculation indicates that the in- place sand volume equals or exceeds the optimal carrying capacity, then no additional dredged sand shall be placed on north beach between the north jetty to Maple Avenue during the cycle, unless mutually agreed upon by the city and the Developer. The carrying capacity of the beach segment between Maple Avenue and Pine Avenue will be calculated and submitted with the sand deposition plan. The amount of sand to be placed in the Maple Avenue to Pine Avenue segment will be determined by calculating the difference between the in-place sand volume and this segment’s optimal sand carrying capacity consistent with the methodology described in the Beach Equilibrium Analysis (2017). The remaining dredged sand shall be placed on middle and south beach segments based upon the sand deposition plan and in consideration of the actual condition of the respective beach segments, public benefits, and public safety. 9. Contractor shall place beach nourishment sand in such a manner that there is a minimum 5’-0” Path of Travel between both public and residential sea walls, to allow for both lifeguard and pedestrian access in between the sea walls and the back sand berm. Back berm shall be no taller than 6’-0” on the eastern aspect of the berm, and shall be groomed and flattened on the top to provide towel space on the north, middle and south beaches, at the end of each dredge event, to the satisfaction of the Parks and Recreation Director, or designee. The constructed beach fill shall be graded on the western side of the beach nourishment in such a manner that does not provide a shelf, but rather a gradual slope into the surf zone. In the event that storm PC RESO NO. 7265 -5- 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 events begin to relocate the front aspect of the graded sand slope during the equilibration process, the berm and slope shall be regraded for public safety purposes. All sand shall be placed in such a manner so as not to block or clog existing drainage unnecessarily. 10. A pre-construction survey of the project area for Caulerpa taxifolia (Caulerpa) shall be conducted in accordance with the Caulerpa Control Protocol (see http://swr.nmfs.noaa.gov/hcd/caulerpa/ccp.pdf) not earlier than 90 calendar days prior to planned dredging and not later than 30 calendar days prior to dredging. The results of that survey shall be provided to the Corps Regulatory Division, NOAA Fisheries, the California Department of Fish and Wildlife and the City Planner at least 5 calendar days prior to initiation of dredging activities. In the event that Caulerpa is detected within the project area, the Developer shall not commence work until such time as the infestation has been isolated, treated, and the risk of spread is eliminated as confirmed in writing by the Corps Regulatory Division, in consultation with NOAA Fisheries, CDFG and the city. 11. Prior to construction, a pre-project eelgrass survey shall be conducted in accordance with the Southern California Eelgrass Mitigation Policy (SCEMP) (http://swr.nmfs.noaa.gov/hcd/eelpol.htm). The results of that survey shall be provided to the City Planner at least 15 calendar days prior to initiation of dredging activities. If the pre-project survey demonstrates eelgrass presence within the project vicinity, a post-project survey should be conducted and impacts mitigated in accordance with the SCEMP. 12. The Developer shall provide copies of current and pending resource agency permits prior to the request to conduct maintenance dredging. 13. The City Planner shall reserve the authority to review and approve the timing of the dredging operation consistent with the time limits outlined in other agency permits. The City Planner’s review and approval shall not be unreasonably withheld. 14. Developer shall submit to the city a Notice of Restriction executed by the owner of the real property to be developed. Said notice is to be filed in the office of the County Recorder, subject to the satisfaction of the City Planner, notifying all interested parties and successors in interest that the City of Carlsbad has issued a Special Use Permit Extension and Amendment by Resolution No. 7265 on the property. Said Notice of Restriction shall note the property description, location of the file containing complete project details and all conditions of approval as well as any conditions or restrictions specified for inclusion in the Notice of Restriction. The City Planner has the authority to execute and record an amendment to the notice which modifies or terminates said notice upon a showing of good cause by the Developer or successor in interest. 15. Developer/Operator shall and does hereby agree to indemnify, protect, defend, and hold harmless the City of Carlsbad, its Council members, officers, employees, agents, and representatives, from and against any and all liabilities, losses, damages, demands, claims and costs, including court costs and attorney’s fees incurred by the city arising, directly or indirectly, from (a) city’s approval and issuance of this Special Use Permit, (b) city’s approval or issuance of any permit or action, whether discretionary or nondiscretionary, in connection with the use contemplated herein, and (c) Developer/Operator’s installation and operation of the facility permitted hereby, including without limitation, any and all liabilities arising from the emission by the facility of electromagnetic fields or other energy waves or emissions. This obligation survives until all legal proceedings have been concluded and continues even if the city’s approval is not validated. PC RESO NO. 7265 -6- 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 16. Developer shall comply with the city's Stormwater Regulations, latest version, and shall implement best management practices at all times. Best management practices include but are not limited to pollution control practices or devices, erosion control to prevent silt runoff during construction, general housekeeping practices, pollution prevention and educational practices, maintenance procedures, and other management practices or devices to prevent or reduce the discharge of pollutants to stormwater, receiving water or stormwater conveyance system to the maximum extent practicable. Code Reminder: 17. Approval of this request shall not excuse compliance with all applicable sections of the Zoning Ordinance and all other applicable city ordinances in effect at time of maintenance dredging, except as otherwise specifically provided herein. NOTICE TO APPLICANT An appeal of this decision to the City Council must be filed with the City Clerk at 1200 Carlsbad Village Drive, Carlsbad, California, 92008, by 5:00 p.m. on September 18, 2017. Pursuant to Carlsbad Municipal Code Chapter 21.54, section 21.54.150, the appeal must be in writing and state the reason(s) for the appeal. The City Council must make a determination on the appeal prior to any judicial review. NOTICE Please take NOTICE that approval of your project includes the “imposition” of fees, dedications, reservations, or other exactions hereafter collectively referred to for convenience as “fees/exactions.” You have 90 days from date of final approval to protest imposition of these fees/exactions. If you protest them, you must follow the protest procedure set forth in Government Code Section 66020(a), and file the protest and any other required information with the City Manager for processing in accordance with Carlsbad Municipal Code Section 3.32.030. Failure to timely follow that procedure will bar any subsequent legal action to attack, review, set aside, void, or annul their imposition. You are hereby FURTHER NOTIFIED that your right to protest the specified fees/exactions DOES NOT APPLY to water and sewer connection fees and capacity charges, nor planning, zoning, grading, or other similar application processing or service fees in connection with this project; NOR DOES IT APPLY to any fees/exactions of which you have previously been given a NOTICE similar to this, or as to which the statute of limitations has previously otherwise expired. . . . . . . . . . . . . . . . . . . PC RESO NO. 7265 -7- 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 PASSED, APPROVED, AND ADOPTED at a regular meeting of the planning Commission of the City of Carlsbad, California, held on September 6, 2017 by the following vote, to wit: AYES: NOES: ABSENT: ABSTAIN: JEFF SEGALL, Chairperson CARLSBAD PLANNING COMMISSION ATTEST: DON NEU City Planner SITE I-5ADAMS ST CANNON R DHARDINGSTPIOPICODRJAMESDRJE FFERSON ST LI N C O L N S T ACACI A A V JUNIPE R A V CARLSBAD BLHOOVER STHI GHL ANDDRSYMEDRVILLAGEDR PACIFIC OCEAN AGUA HEDIONDA LAGOON E L C AMINO R E ALLA COSTA AV A L G A R DCARLSBAD BL SUP 06-10x2A AGUA HEDONDA OUTER LAGOON MAINTENANCE SITE MAP SITE 1 PLANNING COMMISSION RESOLUTION NO. 6181 2 A RESOLUTION OF THE PLANNING COMMISSION OF THE 3 CITY OF CARLSBAD, CALIFORNIA, APPROVING A FLOODPLAIN SPECIAL USE PERMIT TO ALLOW PERIODIC 4 MAINTENANCE DREDGING OF THE AGUA HEDIONDA 5 OUTER LAGOON AND THE PLACEMENT OF DREDGED SAND ON CARLSBAD BEACHES IN LOCAL FACILITIES 6 MANAGEMENT ZONE 1. CASE NAME: AGUA HEDIONDA OUTER LAGOON 7 MAINTENANCE CASE NO: SUP 06-10 o 9 WHEREAS, Cabrillo Power I LLC, "Developer/Owner," has filed a verified 10 application with the City of Carlsbad regarding property described as 11 Portions of Lot "H" of Rancho Agua Hedionda, according to 12 partition Map No. 823, filed November 16,1896 13 ('the Property"); and 14 WHEREAS, said verified application constitutes a request for a Floodplain 15 Special Use Permit as shown on Exhibits "A" - "G" dated October 18, 2006, on file in the 16 Planning Department, AGUA HEDIONDA OUTER LAGOON MAINTENANCE - 17 SUP 06-10, as provided by Chapter 21.110 of the Carlsbad Municipal Code; and18 19 WHEREAS, the Planning Commission did on the 18th day of October, 2006, 20 hold a duly noticed public hearing as prescribed by law to consider said request; and 21 WHEREAS, at said public hearing, upon hearing and considering all testimony 22 and arguments, if any, of all persons desiring to be heard, said Commission considered all factors 23 relating to the Floodplain Special Use Permit. 24 NOW, THEREFORE, BE IT HEREBY RESOLVED by the Planning jL^J 26 Commission of the City of Carlsbad as follows: 27 A) That the foregoing recitations are true and correct. 28 B) That based on the evidence presented at the public hearing, the Commission APPROVES AGUA HEDIONDA OUTER LAGOON MAINTENANCE - SUP 06-10, based on the following findings and subject to the following 2 conditions: 3 Findings: The project is consistent with the Parks and Recreation Element (i.e., Goals, Objectives, r and Policies B.6 and C.I 1) of the General Plan in that the placement of dredged sand on the beach, and the construction of trail improvements along the north shore of 6 the outer lagoon, will enhance public recreation opportunities by increasing the size (i.e., square footage area) of useable public beach and by formalizing a public trail 7 along the north shore of the outer lagoon. 2. The project is consistent with the Open Space and Conservation Element (i.e., Goals, 9 Objectives, and Policies A.I, A.2, A.3, and A.4) of the General Plan in that dredging the outer lagoon and the intake channel, in particular, will allow for the continued flow 10 of fresh, nutrient-rich ocean waters into the lagoon, thereby maintaining/improving the overall health of the lagoon, and the placement of dredged sand on the beach will enhance and protect important City open space resources by assisting the buildup of a deteriorating beach profile and by creating a wider beach which will assist in the protection of coastal bluffs from erosion caused by ocean wave action. 13 3. The project is consistent with the Public Safety Element (Goal A) of the General Plan in that the placement of dredged sand on the beach will increase beach width, which . c will assist in the protection of coastal bluffs from erosion caused by ocean wave action, thereby protecting private and public property in the vicinity of the beach. 16 4. The project is an allowable activity/use in the Open Space Zone and complies with all its 17 standards in that the dredge activity, placement of sand on the beach, and trail improvements along the north shore of the outer lagoon will maintain/improve the overall health of the lagoon by a) dredging the intake channel and ensuring the 19 continued flow of fresh, nutrient-rich ocean waters into the lagoon; b) enhancing the quality of the beach by placing dredged sand on the beach, thereby assisting in the 20 buildup of a deteriorating beach profile; and c) formalizing public access to open space areas through installation of trail improvements. 21 »- 5. The proposed lagoon dredge will not create a hazard or adversely impact development, or adjacent and upstream properties and structures; and the cumulative effect of this project 23 and the adjacent approved projects will not significantly raise the level of the 100-year floodplain (base flood elevation) in that the dredge activity will increase the physical 24 capacity of the lagoon and, therefore, the ability of the lagoon to accommodate flood waters. 26 Conditions; 27 1. If any of the following conditions fail to occur, or if they are, by their terms, to be implemented and maintained over time, if any of such conditions fail to be so implemented and maintained according to their terms, the City shall have the right to revoke or modify all approvals herein granted; deny or further condition issuance of all PCRESONO. 6181 -2- future building permits; deny, revoke, or further condition all certificates of occupancy 2 issued under the authority of approvals herein granted; record a notice of violation on the property title; institute and prosecute litigation to compel their compliance with said 3 conditions or seek damages for their violation. No vested rights are gained by Developer or a successor in interest by the City's approval of this Special Use Permit. 4 2. Staff is authorized and directed to make, or require the Developer to make, all corrections and modifications to the Special Use Permit documents, as necessary to make them 6 internally consistent and in conformity with the final action on the project. Development shall occur substantially as shown on the approved Exhibits. Any proposed development 7 different from this approval shall require an amendment to this approval. 3. Developer shall comply with all applicable provisions of federal, state, and local laws and 9 regulations in effect at the time of building permit issuance. 10 4. If any condition for construction of any public improvements or facilities, or the payment of any fees in-lieu thereof, imposed by this approval or imposed by law on this Project are challenged, this approval shall be suspended as provided in Government Code Section 12 66020. If any such condition is determined to be invalid, this approval shall be invalid unless the City Council determines that the project without the condition complies with 13 all requirements of law. 5. Developer/Operator shall and does hereby agree to indemnify, protect, defend, and hold . _ harmless the City of Carlsbad, its Council members, officers, employees, agents, and representatives, from and against any and all liabilities, losses, damages, demands, claims 16 and costs, including court costs and attorney's fees incurred by the City arising, directly or indirectly, from (a) City's approval and issuance of this Special Use Permit, (b) City's 17 approval or issuance of any permit or action, whether discretionary or nondiscretionary, in connection with the use contemplated herein, and (c) Developer/Operator's installation and operation of the facility permitted hereby, including without limitation, any and all 19 liabilities arising from the emission by the facility of electromagnetic fields or other energy waves or emissions. This obligation survives until all legal proceedings have been 20 concluded and continues even if the City's approval is not validated. 6. Developer shall submit to the Planning Director a reproducible 24" x 36" mylar copy of ~~ the Site Plan reflecting the conditions approved by the final decision making body. 23 7. This project shall comply with all conditions and mitigation measures which are required as part of the Zone 1 Local Facilities Management Plan and any amendments made to that 24 plan prior to any dredging activities. Developer shall also pay any applicable Local Facilities Management Plan fee for Zone 1, pursuant to Chapter 21.90. All such taxes/fees shall be paid prior to any dredging activities. If the taxes/fees are not paid, this 26 approval will not be consistent with the General Plan and shall become void. 27 8. Prior to the issuance of the Special Use Permit, Developer shall submit to the City a Notice of Restriction executed by the owner of the real property to be developed. Said notice is to be filed in the office of the County Recorder, subject to the satisfaction of the Planning Director, notifying all interested parties and successors in interest that the City PCRESONO. 6181 -3- of Carlsbad has issued a Special Use Permit by Resolution No. 6181 on the property. 2 Said Notice of Restriction shall note the property description, location of the file containing complete project details and all conditions of approval, as well as any 3 conditions or restrictions specified for inclusion in the Notice of Restriction. The Planning Director has the authority to execute and record an amendment to the notice which modifies or terminates said notice upon a showing of good cause by the Developer <- or successor in interest. 9. Prior to the start of the dredging project, the Developer shall pay to the City a Trail Plan Check fee and inspection fee in accordance with the current city fee schedule. 7 10. Prior to initiating dredging operations, Developer shall execute a City standard ° Development Improvement Agreement to install and secure with appropriate security as n provided by law public trail improvements including trail signage along the north shore of Agua Hedionda Lagoon from Carlsbad Boulevard to the North County Transit District 10 Railroad right-of-way to City Standards and to the satisfaction of the City Engineer. This condition is contingent upon the City of Carlsbad or other public agency or approved environmental conservancy group accepting on behalf of the public the public trail easement offered for dedication pursuant to prior coastal development permit number 6-93-113 approved by the California Coastal Commission on February 17, 1994. 13 11. This permit authorizes the dredging operation for a period of five (5) years from the 14 date of the Planning Commission approval of this permit. Prior to the permit expiration date, an extension request shall be submitted for consideration by the Planning Commission or a new permit will be required. The Planning Commission will determine whether it is appropriate to extend the permit request and for what period of time. 17 „ . .Engineering: 18 12. The City shall reserve the authority to review and approve the timing of the 19 dredging operation consistent with the time limits outlined in other agency permits. The City's review and approval shall not be unreasonably withheld. 13. At least three (3) months prior to any dredging activity, the applicant shall provide written notice to the City Engineer of such activity. The request shall include the 22 following: 23 a. The applicant shall provide a brief project description of the proposed dredging activity. The description shall include a schedule identifying the beginning and ending dates of the dredging operation, the hours and days of the week for the dredging activity, the anticipated total dredge quantity, the location and quantity for the deposition of sand, the anticipated beginning dates for the 26 deposition on north, middle, and south beaches, and contact information including phone numbers of personnel responsible for the dredging activity. 27 b. A sand deposition plan describing the methods and equipment needed to deposit and move the sand on the beach reaches. The plan should include best management practices for the maximum retention of sand material on the beach. PCRESONO. 6181 -4- This could include such practices as creating a dike parallel to the shoreline to 2 allow the material to fall out of the slurry mix, the methods the construction equipment would be utilized to move the material, and other methods to ensure 3 the maximum amount of sand is placed for beach building. 4 c. The applicant shall provide the City Engineer a plan for interim pedestrian <- circulation control, to include public information signage describing the project. 6 14. Upon receipt of handwritten notice from the applicant, the City Engineer shall forward this notice to the Carlsbad Beach Preservation Committee (BPC). The BPC 7 shall review this notice to ensure the ultimate location for the deposition of the dredged sand is consistent with the recommendations contained in the study of Sediment Transport Condition in the vicinity of the Agua Hedionda Lagoon 9 (December 30, 1998), which states 30% of the dredged sand shall be placed on "North Beach" (as identified in the study) and the remaining sand be placed on 10 "Middle and South Beaches." This requirement represents the minimum amount of sand to be placed on North Beach and does not preclude the placement of any amount of sand more than 30% on North Beach as mutually agreed upon by the , 2 City and the applicant. The limit of sand deposition analysis area begins at the northerly city limit and extends a similar distance south of the outlet jetty. 13 15. The applicant shall provide copies of current and pending resource agency permits prior to the request to conduct maintenance dredging. Code Reminders: 16 16. Approval of this request shall not excuse compliance with all applicable sections of the 17 Zoning Ordinance and all other applicable City ordinances in effect at time of building permit issuance, except as otherwise specifically provided herein.18 17. Any signs proposed for this development shall at a minimum be designed in conformance with the City's Sign Ordinance and shall require review and approval of the Planning 20 Director prior to installation of such signs. 21 22 23 24 25 26 27 28 PCRESONO. 6181 -5- 1 NOTICE 2 Please take NOTICE that approval of your project includes the "imposition" of fees, dedications, reservations, or other exactions hereafter collectively referred to for convenience as 4 "fees/exactions." 5 You have 90 days from date of final approval to protest imposition of these fees/exactions. If you protest them, you must follow the protest procedure set forth in Government Code Section 66020(a), and file the protest and any other required information with the City Manager for processing in accordance with Carlsbad Municipal Code Section 3.32.030. Failure to timely follow that procedure will bar any subsequent legal action to attack, review, set aside, void, or g annul their imposition. 9 You are hereby FURTHER NOTIFIED that your right to protest the specified fees/exactions DOES NOT APPLY to water and sewer connection fees and capacity charges, nor planning, zoning, grading, or other similar application processing or service fees in connection with this project; NOR DOES IT APPLY to any fees/exactions of which you have previously been given a NOTICE similar to this, or as to which the statute of limitations has previously otherwise 12 expired. PASSED, APPROVED, AND ADOPTED at a regular meeting of the planning < 4 Commission of the City of Carlsbad, California, held on the 18th day of October, 2006, by the 15 following vote, to wit: 16 AYES: Chairperson Montgomery, Commissioners Baker, Cardosa, Dominguez, Heineman, Segall, and Whitton 18 NOES: 19 ABSENT: 20 ABSTAIN: 21 22 23 MARTIAL B. MONT^OMER^Whairperson CARLSBAD PLANNING COMMISSION24 25 ATTEST: 26" 27 2g DON NEU Assistant Planning Director PCRESONO. 6181 -6- 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 A RESOLUTION OF THE PLANNING COMMISSION OF THE CITY OF CARLSBAD, CALIFORNIA, APPROVING A RETROACTIVE FIVE YEAR EXTENSION OF A FLOODPLAIN SPECIAL USE PERMIT TO ALLOW PERIODIC MAINTENANCE DREDGING OF THE AGUA HEDIONDA OUTER LAGOON AND THE PLACEMENT OF DREDGED SAND ON CARLSBAD BEACHES IN LOCAL FACILITIES MANAGEMENT ZONE 1. CASE NAME: AGUA HEDIONDA OUTER LAGOON MAINTENANCE CASE NO: SUP 06-10x1 WHEREAS, Cabrillo Power I, LLC, “Developer/Developer,” has filed a verified application with the City of Carlsbad regarding property described as Portions of Lot “H” of Rancho Agua Hedionda, according to partition Map No. 823, filed November 16, 1896, (“the Property”); and WHEREAS, said verified application constitutes a request for a Floodplain Special Use Permit as shown on Exhibits “A” – “E” dated August 1, 2012, on file in the Planning Division, AGUA HEDIONDA OUTER LAGOON MAINTENANCE – SUP 06-10x1, as provided by the conditions of approval of SUP 06-10 and by Chapter 21.110 of the Carlsbad Municipal Code; and WHEREAS, the Planning Commission did on August 1, 2012, hold a duly noticed public hearing as prescribed by law to consider said request; and WHEREAS, at said public hearing, upon hearing and considering all testimony and arguments, if any, of all persons desiring to be heard, said Commission considered all factors relating to the Floodplain Special Use Permit. NOW, THEREFORE, BE IT HEREBY RESOLVED by the Planning Commission of the City of Carlsbad as follows: A)That the foregoing recitations are true and correct. PLANNING COMMISSION RESOLUTION NO. 6904 PC RESO NO. 6904 -2- 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 B) That based on the evidence presented at the public hearing, the Commission APPROVES AGUA HEDIONDA OUTER LAGOON MAINTENANCE – SUP 06-10X1 effective retroactively from October 18, 2011, through October 18, 2016, based on the following findings and subject to the following conditions: Findings: 1. The adopted project findings for SUP 06-10, which are contained in Planning Commission Resolution No. 6181, still apply to this project (SUP 06-10x1). Finding No. 1 and 4, in regard to the trail improvements along the north shore of the outer lagoon, which has been completed, will read as follows: a. The project is consistent with the Parks and Recreation Element (i.e., Goals, Objectives, and Policies B.6 and C.11) of the General Plan in that the placement of dredged sand on the beach, and the construction of trail improvements along the north shore of the outer lagoon, - enhance public recreation opportunities by increasing the size (i.e., square footage area) of useable public beach and by formalizing a public trail along the north shore of the outer lagoon. b. The project is an allowable activity/use in the Open Space Zone and complies with all its standards in that the dredge activity, placement of sand on the beach, and trail improvements along the north shore of the outer lagoon maintain/improve the overall health of the lagoon by a) dredging the intake channel and ensuring the continued flow of fresh, nutrient-rich ocean waters into the lagoon; b) enhancing the quality of the beach by placing dredged sand on the beach, thereby assisting in the buildup of a deteriorating beach profile; and c) formalizing public access to open space areas through installation of trail improvements. Conditions: 1. If any of the following conditions fail to occur, or if they are, by their terms, to be implemented and maintained over time, if any of such conditions fail to be so implemented and maintained according to their terms, the City shall have the right to revoke or modify all approvals herein granted; deny or further condition issuance of all future building permits; deny, revoke, or further condition all certificates of occupancy issued under the authority of approvals herein granted; record a notice of violation on the property title; institute and prosecute litigation to compel their compliance with said conditions or seek damages for their violation. No vested rights are gained by Developer or a successor in interest by the City’s approval of this Special Use Permit Extension. 2. The adopted project conditions for SUP 06-10, which are contained in Planning Commission Resolution No. 6181 still apply to this project (SUP 06-10x1) with the exception of Condition No. 9 and 10 which have been satisfied, and Condition No. 11, which is replaced by Condition No. 3 of this Resolution. 3. This Special Use Permit is granted retroactively for a period of 5 years from October 18, 2011, through October 18, 2016. This permit may be revoked at any time after a public hearing, if it is found that the use has a substantial detrimental effect on surrounding land PC RESO NO. 6904 -3- 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 uses and the public’s health and welfare, or the conditions imposed herein have not been met. This permit may be extended for a reasonable period of time not to exceed 5 years upon written application of the permittee made no less than 90 days prior to the expiration date. The Planning Commission may not grant such extension, unless it finds that there are no substantial negative effects on surrounding land uses or the public’s health and welfare. If a substantial negative effect on surrounding land uses or the public’s health and welfare is found, the extension shall be denied or granted with conditions which will eliminate or substantially reduce such effects. There is no limit to the number of extensions the Planning Commission may grant. 4. Developer shall submit to the City a Notice of Restriction executed by the owner of the real property to be developed. Said notice is to be filed in the office of the County Recorder, subject to the satisfaction of the City Planner, notifying all interested parties and successors in interest that the City of Carlsbad has issued a Special Use Permit Extension by Resolution No. 6904 on the property. Said Notice of Restriction shall note the property description, location of the file containing complete project details and all conditions of approval as well as any conditions or restrictions specified for inclusion in the Notice of Restriction. The City Planner has the authority to execute and record an amendment to the notice which modifies or terminates said notice upon a showing of good cause by the Developer or successor in interest. 5. Developer shall comply with the City's Stormwater Regulations, latest version, and shall implement best management practices at all times. Best management practices include but are not limited to pollution treatment practices or devices, general housekeeping practices, pollution prevention and educational practices, maintenance procedures, and other management practices or devices to prevent or reduce the discharge of pollutants to stormwater, receiving water or stormwater conveyance system to the maximum extent practicable. Developer shall notify prospective owners and tenants of the above requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . Beach Equilibrium Analysis of North Beach Disposal Options for Dredged Sands from Agua Hedionda Lagoon, Carlsbad, CA Submitted by: Scott A. Jenkins, Ph.D. Dr Scott A. Jenkins Consulting 14765 Kalapana St Poway, CA 92064 Submitted to: Sheila Henika, P.E. MBA-TM Cabrillo I LLC Encina Power Station 4600 Carlsbad Blvd. Carlsbad, CA 92008 Draft: 19 May 2017; Revised 15 June 2017 Executive Summary: A detailed set of beach profile surveys at North Beach in Carlsbad CA were provided by Cabrillo Power I LLC, delineating beach surfaces before and after the 2104/2015 dredging of Agua Hedionda Lagoon, (AHL), which placed 64,968 yds3 between Maple Avenue and the north inlet jetty to Agua Hedionda Lagoon. The surveys were accurately performed by Noble Engineers using differential GPS and known historic benchmarks. Three-dimensional CAD models were lofted from the measured points along the four (4)North Beach survey range lines (Cab I-07 – Cab I-10) to delineate the beach surfaces immediately before North Beach dredge disposal (based on the 22 December 2014 profile measurements) and immediately after dredge disposal (based on the 17 April 2017 profile measurements). When these two surfaces were lofted together in a common reference frame, it was determined that 13,780 cubic yards of beach fill have been retained after placing 64,968 cubic yards on North Beach between 23 March 2015 and 15 April 2015. This calculates to an average sand loss rate of 1,969 yds3/day and projects a sand retention time for the entire fill volume of only 33 days. To understand the reasons for the poor sand retention characteristics of North Beach, a baseline beach evolution study was conducted using the Coastal Evolution Model (CEM) to hindcast the fate of beach fill placed on North Beach. The CEM was developed at the Scripps Institution of Oceanography with a $1,000,000 grant from the Kavli Foundation, (see http://repositories.cdlib.org/sio/techreport/58/ ), and is based on latest thermodynamic beach equilibrium equations published in the Journal of Geophysical Research. Inputs to the CEM baseline study were based on measured shoaling wave data, grain size data for the dredged sands, and daily beach fill volumes were derived from the dredge monitoring reports to the Regional Water Quality Control Board (Cabrillo, 2015) and from Cabrillo dredging data bases. Between 1998 and 2015 there have been eight (8) different events when Agua Hedionda dredged sands have been disposed as beach fill on North Beach. Historic dredged sand volumes placed on North Beach ranged from 62,030 yds3 to 161,525 yds3. The CEM beach evolution simulations of these events determined that the minimum sand loss rate occurs when North Beach fill volumes equal to the critical mass critV = 79,471 yds3, which is the theoretical maximum carrying capacity of North Beach for supporting a beach profile in equilibrium. The carrying capacity of a beach is limited by the width of the wave-cut platform in the bedrock on which beach sands have accumulated over geologic time scales. The wave-cut platform at North Beach is only 550 ft. to 600 ft. in width. Many of the beaches throughout north San Diego County are perched on narrow wave-cut platforms. The platforms are narrow because they were carved by wave action into erosion resistant bedrock formations during the present high-stand in sea level, and these narrow wave-cut platforms physically cannot hold large quantities of beach sand; and often become fully denuded during periods of high-energy winter waves. Another contributing factor to the limited carrying capacity of North Beach is that it is exposed to a prevailing negative divergence of drift caused by the way the bathymetry surrounding the Carlsbad Submarine Canyon influences wave shoaling at the southern end of North Beach.. The presence of the Carlsbad Submarine Canyon creates a bright spot in the shoaling wave pattern immediately north of the inlet jetties, where wave heights are locally higher than further to the North around Maple Avenue. The prevailing littoral drift transports beach sand southward throughout the entire Oceanside Littoral Cell; but at North Beach, the alongshore imbalance in wave height causes higher southerly longshore transport rates of sand exiting North Beach at the inlet jetties than enters North Beach at Maple Avenue. This inequality in sand transport rates between the north and south ends of North Beach is divergence of drift, and when the sand transport rates are higher at the down-drift end of the beach, it becomes a constant loss system referred to as negative divergence of drift. So, when beach fill volumes exceed the critical mass of North Beach, the excess sand cannot be supported in equilibrium on its narrow wave-cut platform and is quickly lost to the negative divergence of drift. Historically, the CEM baseline study finds that when a standard 1:10 (rise over run) beach fill template is filled to critical mass, the theoretical minimum sand loss rate to negative divergence of drift is 1,495 yds3/day, and the sand retention time is 53 days. When beach fill sand volume is increased by 103% over critical mass (as occurred during the 2002/2003 dredge event when 161,525 yds3 were placed on North Beach), the retention time is only increased by 26 % from 0T = 53 days to 0T = 67 days. This is not a good return on doubling the investment in beach fill for North Beach because the sand loss rate increases by 61 % to 2,411 yds3/day, or an increase in sand loss of 916 yds3/day over what would have otherwise occurred if the beach fill volume were limited to critical mass. Unfortunately, such increases in sand loss at North Beach correlate with proportional increases of sand influx rates into Agua Hedionda Lagoon. The 2014/2015 survey data show that AHL sand influx rates also increase when the fill volumes are less than the critical mass. Sand influx rates in 2014/2015 were 1,969 yds3/day when only 64,968 cubic yards were placed on North Beach (14,503 yds3 below critical mass requirements). Bear in mind that the critical mass is the minimum volume of sand required to establish an equilibrium beach profile on a wave-cut platform; and a beach is in its most stable state with an equilibrium profile. But with a prevailing negative divergence of drift along North Beach, equilibrium cannot be achieved due to insufficient sand volume, and consequently sand loss rates increase with a destabilized non-equilibrium profile. The worst example of this in the CEM baseline was the 2010/2011 dredging event when only 62,030 yds3 were placed on North Beach, and sand loss rates rose to 2,050 yds3/day with retention times of only 30 days. Following CEM beach evolution analysis of the North Beach historic baseline, attention was given to finding a more effective beach fill template that could increase sand retention using beach fill from Agua Hedionda Lagoon dredging. Beach fill has typically been placed on Carlsbad beaches using a standard beach fill template with a flat backshore platform and a 1:10 (rise over run) seaward facing beach slope extending down to 0 ft. MLLW. This convention dates back to the Regional Beach Sand Project, (AMEC, 2002). However, stable beach profiles in Nature have a much more gradual, curving profile with slopes that range between 1:50 to 3:100. Formulations of equilibrium beach profiles are found in the U.S. Army Corps of Engineers Shore Protection Manual and later the Coastal Engineering Manual; and the latest most advanced formulation is known as the elliptic cycloids. The elliptic cycloid formulation can account for continuous variations in the equilibrium beach profile due to variability in wave height, period and direction when occurring in combination with variations in beach sediment grain size and beach sand volume. Therefore, a new beach fill template has been proposed here for North Beach referred to as the cycloid-dune template (see Figures ES 1-4). The shape of the template is based on the extremal elliptic cycloid which is the equilibrium profile for the highest wave in the period of record. But the extremal elliptic cycloid extends below the MLLW tide line and earth moving equipment which spread out the beach fill cannot work below MLLW. So, the template truncates the extremal elliptic cycloid at MLLW and places the residual volume of critical mass (totaling 43,200 yds3) in a back-beach dune that stretches 3,200 ft. from the Agua Hedionda north inlet jetty to Maple Avenue. While an elliptic cycloid is an equilibrium beach surface, it does not produce a state of zero sand loss in the presence of a negative divergence of drift, which is the persistent littoral drift state along North Beach. When the divergence of drift is negative, the equilibrium cycloidal beach profile will progressively shift landward as it loses sand to negative divergence of drift, eventually intersecting the basement surface of the critical mass envelope. Once this happens, then the cycloidal shape of the profile is disrupted, and the equilibrium state of the profile is lost. The concept behind the cycloid-dune template is that, as the cycloid begins to approach an intersection with the basement surface of the critical mass envelope, (under the erosional effects of continued negative divergence of drift), it also intersects the base of the dune and receives additional sediment cover as the dune erodes and spreads out downslope across the still intact cycloidal surface. Thus, the dune acts as a restoring mechanism that re-supplies the cycloid with sand lost to negative divergence of drift. The construction method envisioned for the cycloid-dune template begins with building the back-beach dune portion first, starting at the north inlet jetty and adding sections to the dredge pipeline until the build-out of the dune reaches Maple Ave. Building the dune first creates a “safe” reservoir of sand before the template can be fully constructed, and sand from this reservoir is only released to the lower eroded basement surface during periods of the highest tides and waves. After the buildout of the dune to Maple Ave, the cycloid portion of the template is laid out beginning from the toe of the dune and spreading the material down slope to MLLW, and working back towards the north inlet jetty, removing pipeline sections as the cycloids are completed CEM beach evolution simulations of the cycloid-dune template show significant improvements in sand loss rate and retention time relative to the historic baseline. Again, the most efficient use of Agua Hedionda dredged sands occurs when the cycloid-dune template is filled to no more than critical mass (79,471 yds3), which reduces average sand loss rates on North Beach to an absolute minimum of 417 yds3/day, while extending retention time to 190.6 days. This is a 3.6 fold improvement in sand retention time over historical dredge disposal practices at North Beach, which could result in a reduction of sand influx rates into Agua Hedionda Lagoon by a similar factor during the first six (6) months following North Beach disposal. If the cycloid-dune template is filled to more than critical mass by adding more sand to the back-beach dune, then North Beach retention time will increase beyond 190.6 days. If the reserve sand volume in the dune were more than doubled to 95,529 yds3 (achieving a total placement volume of 0V = 175,000 yds3) then retention time could be extended to a maximum of 222 days. But, again, this is not a good return on doubling the investment in reserve beach fill for North Beach because retention time is only increased by an extra month while the sand loss rate increases by 89 % to 787 yds3/day. Furthermore, it is simply not possible to place more sand than the critical mass in the back beach dune and not have much of the dune sand prematurely erode during periods of high waves and high tides, because the enlarged dune encroaches further seaward into the middle bar-berm portion of the profile that is subject to more frequent wave attack. On the other hand, under-filling the cycloid-dune template, (by building a reduced dune), leads to accelerated sand loss rates and reduced retention times. The prevailing negative divergence of drift causes the initial cycloid profile in the lower portion of the template to shift landward, and once intersection with the basement surface of the critical mass envelope occurs, there are insufficient sand reserves in the reduced dune to resupply the cycloid in the presence of continued negative divergence of drift. Once the reserve sand supply in the dune is exhausted, the cycloidal shape of the profile is disrupted, and the equilibrium state of the profile is lost. Even so, if the cycloid-dune template is filled to a volume equivalent to the 2104/2015 North Beach disposal event (0V = 64,968 yds3) by using a dune containing only 28,697 yds3, then sand retention times are still significantly better than what was achieved using the standard 1:10 (rise over run) template. With the cycloid-dune template, retention times with only 64,968 yds3 of beach fill were 0T = 117 days and sand loss rates were still small, 554 yds3/day, or a factor of 2.2 better than what was achieved using standard North Beach disposal practices during the 2104/2015 dredge event. With even smaller beach fill volumes, the cycloid-dune retention times and sand loss rates rapidly degrade, but retention times remain equivalent to those of the 2104/2015 North Beach disposal event for beach fill volumes as low as 37,000 yds3, for which the back beach dune was reduced to vanishingly small. Figure ES-1: Proposed beach fill template for North Beach range Cab-I07, based on the extremal equilibrium profile truncated at 0 ft. MLLW with a back beach dune to hold-and- release residual critical mass as the profile adjusts to changing wave climate. Coordinates of Bench Mark: Northing (ft): 1998772.8 Easting (ft): 6226391.4 Figure ES-2: Proposed beach fill template for North Beach range Cab-I08, based on the extremal equilibrium profile truncated at 0 ft. MLLW with a back beach dune to hold-and- release residual critical mass as the profile adjusts to changing wave climate. Coordinates of Bench Mark: Northing (ft): 1999973.2 Easting (ft): 6225671.9 Figure ES-3: Proposed beach fill template for North Beach range Cab-I09, based on the extremal equilibrium profile truncated at 0 ft. MLLW with a back beach dune to hold-and- release residual critical mass as the profile adjusts to changing wave climate. Coordinates of Bench Mark: Northing (ft): 2000268.7 Easting (ft): 6225483.3 Figure ES-4: Proposed beach fill template for North Beach range Cab-I10, based on the extremal equilibrium profile truncated at 0 ft. MLLW with a back beach dune to hold-and- release residual critical mass as the profile adjusts to changing wave climate. Coordinates of Bench Mark: Northing (ft): 2000741.1 Easting (ft): 6225218.1 Beach Equilibrium Analysis of North Beach Disposal Options for Dredged Sands from Agua Hedionda Lagoon, Carlsbad, CA by: Scott A. Jenkins, Ph.D. 1) Beach Profile Surveys and Dredge Disposal: Four beach profile survey range lines were monitored on North Beach (between Maple Avenue and the north inlet jetty to Agua Hedionda Lagoon) before and after the 2014/15 Agua Hedionda Lagoon dredging event. These surveys are plotted in Figures 1-4, and labeled from south to north as: Cab I-07, Cab I-08, Cab I-09, and Cab I-10. The captions in Figures 1-4 also give the California planar coordinates of the bench mark for each range line. Each range line was surveyed four times, three times prior to the most recent Agua Hedionda beach disposal event, Coordinates of Bench Mark: Northing (ft): 1998772.8 Easting (ft): 6226391.4 Figure 1: Measured beach profiles at survey range Cab I-07 on North Beach, before and after the most recent Agua Hedionda Lagoon dredging, which was begun on 31 December 2014 and completed on 15 April 2015. See Figure 5 for bench mark locations. Coordinates of Bench Mark: Northing (ft): 1999973.2 Easting (ft): 6225671.9 Figure 2: Measured beach profiles at survey range Cab I-08 on North Beach, before and after the most recent Agua Hedionda Lagoon dredging, which was begun on 31 December 2014 and completed on 15 April 2015. See Figure 5 for bench mark locations. Coordinates of Bench Mark: Northing (ft): 2000268.7 Easting (ft): 6225483.3 Figure 3: Measured beach profiles at survey range Cab I-09 on North Beach, before and after the most recent Agua Hedionda Lagoon dredging, which was begun on 31 December 2014 and completed on 15 April 2015. See Figure 5 for bench mark locations. Coordinates of Bench Mark: Northing (ft): 2000741.1 Easting (ft): 6225218.1 Figure 4: Measured beach profiles at survey range Cab I-10 on North Beach, before and after the most recent Agua Hedionda Lagoon dredging, which was begun on 31 December 2014 and completed on 15 April 2015. See Figure 5 for bench mark locations. (5 September 2013, 6 November 2014 and 22 December 2014); and once immediately upon completion of beach disposal on 17 April 2015. The dredge logs indicate that no dredging or beach disposal was begun until 31 December 2014. Since the 22 December 2014 beach surveys were performed just 9 days prior to onset of lagoon dredging, these surveys captured the receiver beaches close their most denuded condition. In fact there had been no placement of new sands on these beaches since April 2011; and inspection of the profile measurements in Figures 1-4 indicates little profile change between the 6 November 2014 and 22 December 2014 surveys because much of the beach surface was exposed hard-bottom substrate (bedrock, cobbles and basal conglomerate, see Figure 7). Middle Beach was the first to receive beach fill from the 2014/15 dredge cycle beginning on 31 December 2014, and received a total of 156,056 cubic yards; followed by South Beach that began receiving 73,637 cubic yards of beach fill beginning on 21 February 2015. Unlike previous dredge events, North Beach was the last to receive beach fill, and 64,968 cubic yards were placed there between 23 March 2015 and 15 April 2015, (cf. Appendix-A). Therefore, the 17 April 2015 beach profile surveys represent the receiver beaches in their most built-out state, because these surveys were performed only two days after the beach disposal of dredged sands from Agua Hedionda was completed. Three-dimensional CAD models were lofted from the measured points along the four (4) North Beach survey range lines (Cab I-07 – Cab I-10) to delineate the beach surfaces immediately before dredge disposal (based on the 22 December 2014 profile measurements) and immediately after dredge disposal (based on the 17 April 2017 profile measurements). When these two surfaces were lofted together in a common reference frame (as determined by the bench marks of each survey range line), places where the 17 April 2015 surface intersected the 22 December 2014 surface identified areas along the receiver beach where sand was not retained. Conversely, places where these two beach surfaces remained separated identified areas where dredged sands were being retained to at least some degree. This is shown in Figure 5 where the fully built-out beach surface (post-dredge disposal, 17 April 2015) is lofted in brown, and the severely eroded beach surface (pre dredge disposal, 22 December 2014) is lofted in silver. It is clear from the large areas of silver in this composite CAD model, that beach fill has been poorly retained on North Beach (cf. Cab I-07 – Cab I-10) despite the fact that this was the last beach to receive beach fill. The eroded silver areas on North Beach between Cab I-07 and Cab I-10 in Figure 5 are especially prominent in the seaward half of the bar-berm section of the beach profile, but also in the upper portions of the profile on the berm itself. The mass properties tool of the SolidWorks 3-D CAD software was invoked to calculate the difference in beach volume between the surfaces defined by the 22 December 2014 and the 17 April 2015 surveys, and determined that 13,780 cubic yards of beach fill have been retained after placing 64,968 cubic yards on North Beach between 23 March 2015 and 15 April 2015. This means that only 21% of the beach fill had been retained over a 3 ½ week period that ended just two days after completion of pumping beach fill to North Beach! Clearly sand was being lost at a high rate (1,969 yds3/day, or about 1/3 to 1/2 daily pumping rates) during placement of sand in the beach fill template. A further concern is that the beach fill placed on North Beach is up-drift of the lagoon inlet in the prevailing southerly littoral drift, particularly during the winter season when the large waves that erode the beach are from the northwest. Consequently, when beach fill is not retained it is immediately ingested by Agua Hedionda Lagoon, where it provides no useful function in protecting the shoreline against erosion and wave overtopping, and where it restricts the tidal prism of the lagoon and degrades the lagoon water quality. Figure 5: Three-dimensional composite CAD model of two overlaid beach surfaces on North Beach, 1) immediately before dredge disposal (as delineated in silver from the 22 December 2014 profile measurements) and 2) immediately after dredge disposal (as delineated in brown by the 17 April 2015 profile measurements). CAD model shown with 10 to 1 vertical exaggeration 2) North Beach Sand Retention Issues: The poor sand retention characteristics of North Beach (the receiver beach of back-passing sands) are due to several factors including: the timing of placement of back- passing sands, non-equilibrium distribution of those sands, unfavorable geomorphology, and placing more sand than the geomorphology can support in equilibrium. Beginning with timing, the largest fraction of sand that is lost from the beach fill placed on North Beach occurs in the first few months after placement. Because the least tern nesting season restricts Agua Hedionda Lagoon dredging to the winter season, placement of the beach fill typically occurs in the midst of the onslaught of the largest winter waves. However, during the period when sands from the 2014/15 dredge event were being placed on North Beach, (23 March 2015 – 15 April 2015) the winter waves were not unusually intense, with the highest waves reach Hmax = 1.94 m while average significant wave heights were <H> = 1.1 m, with an average wave period of <T> = 13.8 sec and a typical northwesterly wave direction averaging <> = 2790, (cf Figure 6b). But even these rather ordinary winter waves can exert significant erosional effects due to the way waves refract and shoal at North Beach. The presence of the Carlsbad Submarine Canyon immediately south of Agua Hedionda Lagoon creates a bright spot in the shoaling wave pattern immediately north of the inlet jetties, where wave heights are locally higher than further to the North around Maple Ave. This alongshore imbalance in wave energy leads to a negative divergence of drift in the longshore transport rates, which in turn causes higher southerly longshore transport rates of sand exiting North Beach at the inlet jetties than enters North Beach at Maple Ave, (see Section 5 for more detail). So we turn our attention to how the North Beach fill has been placed and what quantities. Engineered beach fill has typically been placed on Carlsbad beaches with a 1:10 (rise over run) slope. This convention dates back to the Regional Beach Sand Project, (AMEC, 2002). However, stable beach profiles in Nature have a much more gradual, curving profile with slopes that range between 1:50 or 3:100, (Inman et al., 1993). The theory on equilibrium beach profiles began with Dean (1977) and Bowen (1980) who developed formulations for an equilibrium profile having the form, mAxh, where h is the local water depth, x is the horizontal distance offshore, m = 2/3, and A is an empirical factor. Later Dean (1991) developed analytic approximations for the empirical factor, A , and that formulation was incorporated into the U.S. Army Corps of Engineers Shore Protection Manual and later the Coastal Engineering Manual. However, recently Jenkins and Inman, (2006), proved that the Dean (1977 and 1991) solutions are not unique, and represent only one of a family of equilibrium beach profiles known as elliptic cycloids. The elliptic cycloid formulation can account for continuous variations in the equilibrium beach profile due to variability in wave height, period and direction when occurring in combination with variations in beach sediment grain size and beach sand volume. Equilibrium beach profiles obey the maximum entropy production formulation of the second law of thermodynamics, and are the most efficient shape for a beach profile because it adjusts itself to dissipate all of the available wave energy. When the waves encounter an inefficient, non-equilibrium beach shape, such as a steeply sloping beach fill templates, then the wave energy is not fully dissipated and the excess wave energy begins eroding and moving that beach fill around until an equilibrium profile is finally achieved. While this is occurring, the beach fill can be highly mobile, particularly in large winter waves; and at Carlsbad, the net southward flowing longshore currents (particularly in Figure 6a: Shoaled significant wave heights, periods and directions at Carlsbad State Beach based on back refraction of wave monitoring data from CDIP Station 043 at Camp Pendleton during the beach survey period. Data shown in black occurred during the 2014/15 Agua Hedionda Lagoon dredging event. Figure 6b: Shoaled significant wave heights, periods and directions at Carlsbad State Beach based on back refraction of wave monitoring data from CDIP Station 043 at Camp Pendleton during the North Beach disposal period, 23 March – 15 April 2015. winter) will rapidly transport the eroded beach fill from North Beach toward the south and the inlet to Agua Hedionda Lagoon. There are also geomorphic factors that contribute to poor retention of Agua Hedionda dredge sands at the North Beach disposal site. A sandy beach cannot be supported in equilibrium against wave forces without a wave-cut platform in the bed rock to provide a foundation. Wave cut platforms are notches that have been eroded in the bed rock during protracted still-stands in sea level. Once formed, sediment collects in these notches forming a beach which is subsequently molded into an equilibrium shape by wave action. Figure 7a shows an annotated seismic reflection profile measured by USGS across the continental shelf off Carlsbad CA on range 223X of the 1991 Kolpack surveys, (Kolpack, 1991). It shows a series of wave-cut platforms that were formed at present and earlier still-stands of sea level, and subsequently covered with sediment. The most striking feature in Figure 7a is how much more pronounced the paleo wave-cut platforms are than the modern platform; and how very thin the sediment cover is over the modern wave-cut platform, as compared with the thickness of Holocene sediment over the paleo platforms. Although the paleo platforms have been subjected to longer periods of sedimentation, the geometric constraints imposed by small wave-cut platforms prevent them from retaining thick layers of sediment cover. Many of the beaches throughout north San Diego County are perched on narrow wave-cut platforms. The platforms are narrow because they were carved by wave action from erosion resistant Del Mar formation during the present high-stand in sea level, and these narrow wave-cut platforms physically cannot hold large quantities of beach sand; and often become fully denuded during periods of high-energy winter waves, as shown in Figure 7b. Sub-bottom surveys by Elwany, et al., (1999) discovered narrow wave cut platforms and exposed hard bottom substrate in the surfzone and nearshore at North Beach and South Beach (Figure 8) while 1884 railroad surveys reveal beach cobble ridges before the influence of Mankind at Agua Hedionda Slough, (e.g. HWY 101 and the deep water lagoon). When beach cobble ridges and hard-bottom features are found this close to shore, it indicates that these beaches (particularly, North Beach and South Beach) are not geomorphically well suited to retain large volumes of sand. In the particular case of North Beach, attempts to back-pass and place more sand there than its carrying capacity will simply result in low retention time and increased sand influx into Agua Hedionda Lagoon. The remainder of this report focuses on determination of the carrying capacity at North Beach and the optimal distribution of that carrying capacity within a beach fill template in order to maximize sand retention time of dredged sands. 3) Critical Mass and North Beach Equilibrium Profiles: The critical mass is the minimum volume of sediment cover required to maintain equilibrium beach profiles and represents the nominal carrying capacity of a particular beach. When a long term collection of beach profiles are plotted together over a broad range of wave heights, a well-defined envelope of variability becomes apparent, (Figure 9a). This envelope of profile variability is referred to as the critical mass envelope, and the volume of sand within critical mass envelope, cV , increases with increasing wave height and period but decreases with increasing beach grain size, as shown in Figure 9b. The critical mass envelope is always limited by the breadth of the wave cut platform, a) b) Figure 7: Wave-cut platforms in North San Diego County: a) Annotation of USGS Geopulse sub- bottom seismic profile along range line 223-X in the inner shelf off Carlsbad showing present and ancient wave cut platforms (after Kolpack, 1991); b) exposed wave cut platform in Solana Beach during the 1983 El-Nino winter. Figure 8: Nearshore survey (left) showing exposed rocky reefs, outcrops and other hard bottom substrate; and (right) 1884 railroad survey map showing beach cobble ridge, both indicating minimal sediment cover on the beaches around Agua Hedionda Lagoon. Figure 9: Features of the critical mass of sand: a) critical mass envelope for waves ranging from 1m to 5m in height; b) volume of critical mass as a function of wave height and sediment grain size; c) variation in the thickness of the critical mass as a function of distance offshore. which forms a hard-bottom boundary condition on the critical mass envelope. The best way to calculate the critical mass is to find the volume between the wave cut platform (or its layer of basal conglomerate) and the elliptic cycloid equilibrium profile that corresponds to the native beach grain size in combination with the wave height and period of the extreme event wave in the period of record. The volume integral between the surfaces of the wave cut platform and the extremal event elliptic cycloid then give the critical mass volume. In the case of North Beach, the sub-bottom reflection data is too spotty between Maple Avenue and the north inlet jetty of Agua Hedionda Lagoon to resolve the complete surface of the wave-cut platform along the 3,200 ft. length of the North Beach disposal site (between north inlet jetty to Maple Avenue). Therefore we will use the surface given by the 22 December 2014 beach surveys as a surrogate bottom of the critical mass envelope. This is a reasonable approximation because there has been no placement of new sands on North Beach since the 2010/11 dredge event, which only placed 62,030 cubic yards on North Beach in April 2011 (cf. Appendix-A). Inspection of the profile measurements in Figures 1-4 indicates little profile change between the 6 November 2014 and 22 December 2014 surveys because much of the beach surface was exposed hard-bottom substrate (bedrock, cobbles and basal conglomerate). The extremal elliptic cycloid equilibrium profile is a curve that is traced by a point on the circumference of a rolling ellipse, see Figure 10b. It is calculated from Jenkins and Inman (2006) using the following: 1)2(sin cos1 2 ZI xh e       (1) Here Z1 is the elevation of the berm crest (cf. Figure 10a) given by Hunt’s Formula [Hunt, 1959; Guza and Thornton, 1985; Raubenheimer and Guza, 1996]: b1HZ (2) In equation (2), is the runup factor taken herein as 76.0, and bH is the breaking wave height. The cycloid in (1) is based on the elliptic integral of the second kind that has an analytic approximation, 2/)2(2)2(eIe, where e is the eccentricity of the ellipse given by 22/1 abe, with, semi-major and semi-minor axes are a, b, (cf. Figure 10b). The wave parameter,, in equation (1) is given by: 5/2 5/1 5/42/1 2        g H g Hb (3) here /period2is radian frequency,H is incident wave height, g is the acceleration of gravity, and is the wave breaking criteria taken as = 0.8. The rolling angle of the ellipse is:             ch H21arccos (4) Figure 10. Equilibrium beach profile theory: a) nomenclature, b) mathematical basis for an elliptic cycloid, c) Typical range of elliptic cycloids on a 700 m wide wave-cut platform. Cycloids with eccentricity e = 0 are the same basic formulation as the original Dean (1977 and 1991) solutions in the U.S. Army Corps of Engineers Coastal Engineering Manual where  is the shoaling factor relating breaker height to incident wave height, = H / Hb, which for shoaling Airy waves, becomes 5/125/15/22   gH . The closure depth, ch in equation (4) is grain size and wave period dependent and is given by:       50 0 c ecsinh D D kh HKh (5) where cghk/is the shallow water form of the wave number, Ke and ~ 2.0 are non- dimensional empirical parameters, set at Ke = 2.0 and ~ 0.33; 50D is the median grain size; and D0 is a reference grain size taken as 0D = 100 m. Equation (5) is transcendental and is solved numerically within the CEM. Calculation of the extremal elliptic cycloid equilibrium profile at North Beach requires knowledge of the characteristic median grain size, 50D, of the dredged sediments to be placed there. Recent sediment grain size analyses by Merkel, (2008) based on three sampling locations on the flood tide bar in the West Basin of Agua Hedionda Lagoon (Samples L1 – L3) were compared against native sediments on the three receiver beaches (RB1-RB3). These grain size distributions are plotted in Figure 11. Note North Beach is represented by samples RB1. Grain sizes at the lagoon sample sites and beach sites were similar with median grain sizes of 0.32 millimeters (320 microns) on the flood tide bar in the West Basin of Agua Hedionda, while residual sediments that still remained on North Beach prior to disposal of material from the 2008/09 dredging averaged 0.374 millimeters (374 microns). To determine the highest waves to effect North Beach disposal, the waves measured at ½ hour sampling intervals at CDIP Station 043 were back refracted into deep water from the monitoring location off Camp Pendleton, and then forward refracted into North Beach. An example of this procedure is shown in Figure 12 for a wave occurring 8 January 2002. This effort produced a continuous wave record throughout the historic period when North Beach disposal of Agua Hedionda Lagoon dredged sands was practiced, (1998-2015). The highest energy wave (extremal) event occurred in January 2007, when a Gulf of Alaska storm brought 4.8 m high waves approaching Carlsbad at 276 0 with a 15 second periods. This extreme event wave was used to calculate the extremal elliptic cycloids on North Beach. To calculate the critical mass of North Beach, we combine the extremal waves with the 50D grain size values from Figure 11 to solve equations (1) – (5) for the extremal elliptic cycloid profile. These profiles are plotted on the North Beach Range survey range lines (Cab-I-07 – Cab I-10) in Figures 14 – 17. These profiles represent the beach shape that can be sustained in an equilibrium state during the most severe wave events of the 1998-2015 North Beach disposal period. These profiles form the top of the critical mass envelope, while the most eroded profile (from the 22 December 2014 surveys) to have occurred in that same period of record defines the bottom of critical mass envelope. When lofted in the 3-D CAD SolidWorks software, the SolidWorks volume tool calculates the critical mass envelope to hold of 79,471 cubic yards Figure 11: Grain size distributions form Agua Hedionda Lagoon (Samples L1 – L3) and from the receiver beaches (RB1-RB3). Note North Beach is represented by samples RB1, (from Merkel, 2008). Figure 13: Shoaled significant wave heights, periods and directions at Carlsbad State Beach based on back refraction of wave monitoring data from CDIP Station 043 at Camp Pendleton for the period of record of North Beach disposal, 1998-2016. Figure 14: Critical mass envelope at range line Cab I-07 on North Beach based on the extremal elliptic cycloid solution using a 4.8 m high design wave height with 15 second wave period. Figure 15: Critical mass envelope at range line Cab I-08 on North Beach based on the extremal elliptic cycloid solution using a 4.8 m high design wave height with 15 second wave period. Figure 16: Critical mass envelope at range line Cab I-09 on North Beach based on the extremal elliptic cycloid solution using a 4.8 m high design wave height with 15 second wave period. Figure 17: Critical mass envelope at range line Cab I-10 on North Beach based on the extremal elliptic cycloid solution using a 4.8 m high design wave height with 15 second wave period. along the entire 3,200 ft of the North Beach disposal site. This volume represents the optimal carrying capacity of the North Beach disposal site. Lesser amounts of beach fill will not be able to sustain an equilibrium profile during the highest energy wave events; and without an equilibrium profile, the beach will not dissipate all the incident wave energy, and the excess wave energy will erode the beach. If North Beach is over-nourished with more than the critical mass of sand, then two processes will intervene: a) the excess sand will spill off the wave cut platform (which is 500 ft. to 600 ft. wide) and be re-suspended over the rocky outcrops and hard bottom substrate at North Beach (cf. Figure 8); and/or b) the excess sand will be swept away by the net longshore transport (littoral drift) which flows from north to south throughout the Oceanside Littoral Cell. Figure 18: Oceanside Littoral Cell showing net north-to-south littoral drift, (from Inman and Brush, 1970) 4) Cycloid Beach-Fill Template Design: Ideally the optimal beach fill templates for North Beach would duplicate the critical mass envelope in Figures 14-17, as these would prescribe an adequate amount of sand to support an equilibrium profile in the presence of extreme event waves without exceeding the carrying capacity of the otherwise limited wave cut platform that exists there. However, Figures 14-17 indicate that the critical mass envelope extends well below mean lower low water (MLLW) to depths ranging from -4 ft. MLLW to -8 ft. MLLW. With present beach fill construction methods, it is not possible to build a template that extends below the waterline. Beach fill is pumped to North Beach via a hydraulic dredge pipeline and initially deposited as slurry. After the slurry dewaters, the sands are spread out across the beach using conventional earth-moving equipment, (Figure 19) which cannot effectively operate in anything deeper than ankle deep water. Therefore, we must pose a beach-fill template that adapts to this construction constraint. We begin by examining the percentage of time that a dry beach is available for construction operations at the lower end of the beach profile during in the months of September to mid-April, (the months during which dredge disposal is permitted in order to avoid impacting the least tern nesting season). Figure 19 plots the relationship between ocean water level and percent time a given elevation remains dry, (referred to as the hydroperiod function), based on ocean water levels measured at the nearby Scripps Pier tide gage (NOAA # 9410230). Figure 19 indicates that the beach fill construction operations can proceed down to elevations as low as 0 ft. MLLW at least 7% of the time, or during about 50 hours in a given month. These times are clustered during the spring tides that occur twice each month. If the beach fill template is filled from the top down (ie, spreading sand at the highest elevations of the template first, and then proceeding downslope towards the lowest end), then 50 hours should be adequate to allow filling the lowest portion of a template that terminates at 0 ft. MLLW. A significant fraction of the critical mass envelope in Figures 14-17 lies below the 0 ft. MLLW water level, and if the extremal cycloid profile is terminated at that elevation in the beach fill template design, then additional sand must be added elsewhere to the template in order to achieve the critical mass volume along the entire 3,200 ft. reach of the North Beach disposal site. The additional sand is provided by combining a back-beach dune with the elliptic cycloid that has been truncated at 0 ft. MLLW. The back-beach dune placement strategy was first implemented in Carpinteria by Bailard and Jenkins (1980 and 1983) and later during the replacement of seawalls at Mission Beach Sea (Jenkins 2014) and Del Mar (cf Figure 19a.). These previous implementations of the back-beach dune strategy involved very popular beach sites, yet no adverse recreational incidences were encountered. The back beach dune is a conservation/storage mechanism that prevents rapid sand loss from over-builds of the intertidal portion of the beach profile, yet still allows the fill site to receive its full allocation of critical mass, and provides gradual re-nourishment as the dune erodes during brief periods of spring tides and/or high waves. The dune proposed for the North Beach disposal site is shown in Figure 19b, and is roughly 9 ft high and 55 ft. wide, with a reserve storage capacity of 13.5 cubic yards per running ft. of beach. When built along the 3,200 ft. length of the North Beach disposal site, this dune will provide 43,200 yds3 sand perched in the upper portion of the truncated equilibrium cycloid profile. The beach fill templates that result from this strategy are shown in Figures 21-24 for North Beach survey range lines Cab I07 – Cab I-10. When lofted over the entire 3,200 ft of the North Beach disposal site yields using the SolidWorks 3-D CAD software, calculates that these templates will provide 79,455 cubic yards of disposal volume, which compares almost exactly with the required critical mass of 79,471 cubic yards, (the optimal carrying capacity of the North Beach disposal site.) Figure 19: Hydroperiod function of ocean water levels during the months of September-April, based on the Scripps Pier tide gage (NOAA # 9410230; based on the 1983-2001 tidal epoch, (from Jenkins and Taylor 2015; and Jenkins and Wasyl, 2011) a) b) Figure 20: The back-beach dune beach fill placement strategy, a) as implemented in Del Mar during seawall replacement; and b) as proposed at North beach in combination with a truncated elliptic cycloid beach profile. Figure 21: Proposed beach fill template for North Beach range Cab-I07, based on the extremal equilibrium profile truncated at 0 ft. MLLW with a back beach dune to hold-and-release residual critical mass as the profile adjusts to changing wave climate. Coordinates of Bench Mark: Northing (ft): 1998772.8 Easting (ft): 6226391.4 Figure 22: Proposed beach fill template for North Beach range Cab-I08, based on the extremal equilibrium profile truncated at 0 ft. MLLW with a back beach dune to hold-and-release residual critical mass as the profile adjusts to changing wave climate. Coordinates of Bench Mark: Northing (ft): 1999973.2 Easting (ft): 6225671.9 Figure 23: Proposed beach fill template for North Beach range Cab-I09, based on the extremal equilibrium profile truncated at 0 ft. MLLW with a back beach dune to hold-and-release residual critical mass as the profile adjusts to changing wave climate. Coordinates of Bench Mark: Northing (ft): 2000268.7 Easting (ft): 6225483.3 Figure 24: Proposed beach fill template for North Beach range Cab-I10, based on the extremal equilibrium profile truncated at 0 ft. MLLW with a back beach dune to hold-and-release residual critical mass as the profile adjusts to changing wave climate. Coordinates of Bench Mark: Northing (ft): 2000741.1 Easting (ft): 6225218.1 Figure 25: Three-dimensional CAD model of the proposed composite cycloid/dune beach fill template on North Beach, where the silver surfaces indicate the beach surface on which the template is built (from the 22 December 2014 profile measurements) and brown represents the beach surface resulting from the proposed beach fill template. 5) Beach and Shoreline Evolution Analysis of North Beach Disposal Options The potential benefits of the cycloid beach fill templates for North Beach disposal of dredged sands from Agua Hedionda Lagoon are evaluated with Coastal Evolution Model (CEM) whose architecture is shown in Figure 26 with computer code detailed in Jenkins and Wasyl, 2005, which is available on-line from the Digital Library of the University of California at (http://repositories.cdlib.org/sio/techreport/58/). In the work described herein, the CEM is driven by the CDIP wave measurements in Figures 6a & 6b and calibrated with beach profile measurements and dredge disposal volumes preceding and following the most recent Agua Hedionda Lagoon dredging, December 2014 – April 2015. The Coastal Evolution Model (CEM) is a process-based numerical model. It consists of a Littoral Cell Model (LCM) and a Bedrock Cutting Model (BCM), (Figure 26), both coupled and operating in varying time and space domains determined by sea level and the coastal boundaries of the littoral cell at that particular sea level and time. Over the time scales of this study, the LCM is the relevant module. At any given sea level and time, it accounts for transport of mobile sediment along the coast by waves and currents. The BCM accounts for the cutting of bedrock once the sediment cover is denuded by wave erosion. However bedrock cutting, and notching of the bedrock to form a wave cut platform is a process that occurs over decadal to millennial time scales. Figure 26: Architecture of the Coastal Evolution Model (CEM); from Jenkins and Wasyl, (2005). In the LCM, the coastline of the far-field computational cell is divided into a series of coupled control cells, as illustrated schematically in Figure 27b. Each control cell is a small coastal unit of uniform geometry where a balance is obtained between shoreline change and the inputs and outputs of mass and momentum. The model sequentially integrates over the control cells in a down-drift direction so that the shoreline response of each cell is dependent on the exchanges of mass and momentum between cells, giving continuity of coastal form in the down- drift direction. While the overall computational domain of the far-field cell remains constant throughout time, the beach profile within the individual control cells can change shape or shift on or offshore, as shown in Figure 27c, in response to changes in wave height or longshore transport rates, or due to the introduction of new sediment from dredge disposal as shown in Figure 27a. These changes are computed from time-stepped solutions to the sediment continuity equation (otherwise known as the sediment budget) applied to the boundary conditions of the coupled control cell mesh for the larger scale region (farfield) round Agua Hedionda Lagoon, as in Figure 28. The sediment continuity equation is written (Jenkins, et al, 2007): )()(tRtJy vUy v ytd vd l         (5) Where v is the beach volume per unit length of shoreline (m3/m),  is the mass diffusivity, lU is the longshore current, J(t) is the flux of new sediment into the control cell from dredge disposal and R(t) is the flux of sediment lost from the control cell due to the tidal influx of sediment into Agua Hedionda Lagoon. The first term in (1) is the surf diffusion while the second is divergence of drift. For any given control cell that does not enclose the lagoon inlet, equation (5) may be discretized in terms of the rate of change of beach volume, V, in time, t , given by: )(tJqqdt dV outin  (6) and dttJqqVoutin)]([ Over any given period of time, tnT, comprised of n number of time steps of interval t, the volume change of the beach can be computed by discretizing equations (6) according to: tnnJqqVoutin n )]([1 (7) Referring to the control cell schematic in Figure 27c, sediment is supplied to the control cell by dredged beach fill,)(tJ , or by the influx littoral drift from up-coast sources, 1Linqq, (where Lq is the longshore transport rate on the updrift side of the control cell). Sediment is lost from the control cell due to the action of wave erosion and expelled from the control cell by exiting Figure 27: Computational approach for modeling shoreline change after Jenkins, et. al., (2007). Figure 28: Coupled control cell mesh used to in the CEM to model the beach evolution during Agua Hedionda dredge disposal operations . littoral drift, 2Loutqq, or by becoming ingested by the lagoon’s tidal inlet, )(tR . Here fluxes into the control cell (J(t) and 1Lq) are positive and fluxes out of the control cell (2Lq and tideq ) are negative. The beach sand volume change, dV/dt, is related to the change in shoreline position, dX/dt, according to: lZdt dX dt dV  (8) where chZh1 Here, h is the height of the shoreline flux surface equal to the sum of the closure depth below mean sea level, hc, and the height of the berm crest, Z1, above mean sea level (from Hunt’s Formula.); and l is the length of the shoreline flux surface (see Figure 1b). Hence, beaches and the local shoreline position remain stable if a mass balance is maintained such that the flux terms on the right-hand side of equation (2) sum to zero; otherwise the shoreline within each control cell will move during any time step increment as: n outinoutin tnnJqqyhdttJqqyhx 1 )(1)(1 (9) When dredge disposal produces a large episodic increase in J, an accretionary bulge in the shoreline (like a river delta) is initially formed (cf. 1tin Figure 27a). Over time the accretionary bulge will widen and reduce in amplitude under the influence of surf diffusion and advect down-coast with the longshore current, forming an accretion- erosion wave (cf. 2t & 3t in Figure 27a). The local sediment volume varies in response to the net change of the volume fluxes, between any given control cell and its neighbors, referred to as divergence of drift = outinqq , see Figure 27c. The mass balance of the control cell responds to a non-zero divergence of drift with a compensating shift,x, in the position of the equilibrium profile whose shape is calculated from equations (1) – (4) after Jenkins and Inman, (2006). This is equivalent to a net change in the beach entropy of the equilibrium state. The divergence of drift is given by the continuity equation of volume flux, requiring that dq/dt on the left hand side of equation (5), is the net resultant of advective and diffusive fluxes of sediment plus the influx of new sediment, J, from dredge disposal, per the right hand side of equation (1). In response to the rate of change of volume flux through the control cell, the equilibrium profile will shift in time according to equation (9). If the divergence of drift is positive because more sand fluxes into the control cell due to longshore transport than leaves the cell, (021LLoutinqqqq ), then the equilibrium beach profile in that cell will shift seaward. Conversely, if the divergence of drift is negative because less sand fluxes into the control cell than is expelled from the cell by longshore transport, (021LLoutinqqqq ), then the equilibrium beach profile in that cell will shift landward, as diagramed schematically in Figure 27c. If a negative divergence of drift causes the equilibrium profile to shift sufficiently landward that it intersects the basement surface of the critical mass envelope, then the cycloidal shape of the profile is disrupted, and the equilibrium state of the profile is lost. The formulation for the longshore transport rate Lq is taken from the work of Komar and Inman (1970) according to:  byxnLSCKq (10) where Lq is the local potential longshore transport rate; Cn is the phase velocity of the waves; bbyxEScossinis the radiation stress component; b is the breaker angle relative to the shoreline normal; 28/1 bgHE is the wave energy density; ρ is the density of water; g is the acceleration of gravity; bH is the breaking wave height; and, K is the transport efficiency equal to: rbcK2.2 (11) 2 2tan2   b rb H gc (12) Here rbc is the reflection coefficient which is calculated from the mean bottom slope,  (which is known either from the measured profiles or from the elliptic cycloids); and,  is the radian frequency = 2π/T, where T is the wave period. These equations relate longshore transport rate to the longshore flux of energy at the break point which is proportional to the square of the breaking wave height and breaker angle. By this formulation, the CEM computer code calculates a local longshore transport rate for at the up-drift and down-drift sides of each side of each control cells of the mesh in Figure 28. 5.1 Calibration of the Coastal Evolution Model for North Beach: The Coastal Evolution Model (CEM) for North Beach was calibrated using the measured pre- and post-dredging beach profiles for North Beach during the 2014-2015 dredging event, in conjunction with daily beach fill placement volumes as reported in the monitoring report to the Regional Water Quality Control Board, San Diego Region, (Cabrillo, 2015). Wave forcing for the CEM was based on shoaling wave data from Figure 6b, while beach fill grain size was based on Figure 11. Daily beach fill volumes were assumed to be laid out over the 22 December 2014 profiles from Figures 1-4 in a standard beach fill template with a flat backshore platform and a 1:10 (rise over run) seaward facing beach slope extending down to 0 ft. MLLW. Throughout the North Beach disposal period, that began on 23 March 2015 and ended on 15 April 2005, daily beach fill increments ranged from 1,050 yds3/day to 6,060 yds3/day and were successively added to the North Beach control cells in Figure 28, while the wave forcing continued to rearrange those fill volume increments according to flux balance relations in equations (5) – (9). Free parameters in the CEM, including the mass diffusivity in equation (5) and the longshore transport efficiency in equation (10) were adjusted through successive iterative simulations until the change in beach sand volume between 23 March 2015 and 17 April 2015 (when the post dredging beach surveys were done) matched the volumetric changes of the measured profiles in Figures 1-4. These volumetric changes were computed by the SolidWorks 3-D CAD model in Figure 29. Figure 29: SolidWorks 3-D CAD model of a composite surface overlay of the modeled post- disposal North Beach surface (brown) and the pre-disposal North Beach surface (silver). The SolidWorks mass properties tool calculates a volume of 13,780 yds3, representing the volume of sand retained after placing 64,968 yds3 over a 24 day period of beach nourishment. In Figure 29, the CEM modeled beach surface on 17 April 2015 (represented in brown) shows numerous patches where erosion has occurred and the pre-disposal beach surface (represented in silver) is exposed. The mass properties tool in SolidWorks calculates that the volume in the region between the two surfaces (representing the volume of beach fill retained) is 13,780 yds3, which matches the retention calculated directly from the pre- and post dredging beach profile measurements in Figures 1-4. The time stepped CEM wave-driven flux calculations which led to this perfect calibration result are plotted in Figure 30. Initially, as sand was being placed on North Beach, waves were small, short period and approaching from the southwest (cf Figure 6b). Consequently, the calibration simulation begins with weak northward flowing longshore transport, Figure 30a, causing some of the previously placed dredged sands on Middle Beach to be transported around the inlet jetties during ebb tide and arrive at North Beach. During this early period, more sand enters the North Beach control cells at the north inlet jetty, than leaves North Beach from the control cells at Maple Ave, and the difference between the cumulative net transport at the north jetty vs Maple Ave (Figure 30 b) initially creates a positive divergence drift (Figure 30c). Consequently, North Beach gains sand volume during the first 5 days from wave driven transport, irrespective of the additional gains from North Beach dredge disposal. But then, by day 6, circa 28 March 2015, a large west/northwest storm swell arrives with waves reaching 2 m in height prior to breaking (cf. Figure 6b). Coinciding with this large swell, the longshore transport reverses direction toward the south and increases in rate, (Figure 30a) resulting in cumulative net transport toward the south at the north jetty that exceeds cumulative net transport into North Beach at Maple Ave (Figure 30 b). The divergence of drift turns negative and remains that way throughout the remainder of the North Beach disposal activities, resulting in a loss of 51,188 cubic yards of sand by 17 April 2015 due to wave-driven transport (Figure 30 c). Negative divergence of drift is prevalent along North Beach because of the way the prevailing west/northwest swell and wind waves are refracted around the Carlsbad submarine canyon, creating higher shoaled wave heights at the southern end of North Beach than found further north near Maple Ave, where refraction effects of the Carlsbad Submarine Canyon are weaker, (cf. Figure 12). When the net sand loss to divergence of drift is superimposed on the incremental sequence of beach fill being placed on North Beach, we get a look at how the sand retention on North Beach varies throughout the disposal period (Figure 31). It appears from the black line in Figure 30 that sand retention with the standard 1:10 (rise over run) beach fill template reaches a fairly constant level of about 20,000 cubic yards throughout most of the North Beach disposal period, before falling off to 13,780 yds3. The retained sand volume never reaches anything close to the total sand volume placed on North Beach (which was 0V = 64,968 yds3). By the time the post dredging beach surveys were performed on 17 April 2015 (26 days after beach fill placement began), only 21% of the total volume of sand placed on North Beach remained, and the average rate of loss of beach fill was dtdV/= 1,969 yds3/day. Based on this average loss rate, the retention time,0T , for fill placed on North Beach during the 2014/2015 dredging event was 969,1 968,64 / 00 dtdV VT = 33 days (13) Figure 30: Time stepped wave-driven fluxes during the North Beach CEM calibration: a) longshore transport rate, b) cumulative net transport; and, c) cumulative divergence of drift. Figure 31: CEM simulation of temporal variation in beach sand retention on North Beach (black line) as a result of the net between the incremental sequence of beach fill placement (green line) and the wave-driven divergence of drift (red line). It should be remembered that the very low retention time from equation (13) was a consequence of several factors: 1) placement of a fill on a highly eroded North Beach surface, that had probably been eroded to the basement of the critical mass envelope, (since it had been 3 years since previous nourishment was provided by lagoon dredging disposal); and 2) the fill placed in 2015 was less than the critical mass requirement and was laid down in anon-equilibrium profile shape. In the following section, we evaluate potential improvements in beach fill retention time using the composite cycloid-dune beach fill template and the appropriate amounts of beach fill volume. 5.2 Performance Simulations of the Proposed Cycloid Beach Fill Template: In this section, the calibrated Coastal Evolution Model (CEM) is run in long-term simulations of the fate of beach fill placed on North Beach throughout the entire period of record (1998-2015) that Agua Hedionda Lagoon dredged sands have been disposed as beach fill on North Beach. Wave forcing for these simulations was based on shoaling wave data from Figure 11 for the period 1998-2016, while beach fill grain size was based on Figure 11. Daily beach fill volumes were derived from the dredge monitoring reports to the Regional Water Quality Control Board (Cabrillo, 2015) and from the Cabrillo Power dredging data base contained in an Excel spreadsheet < Dredge History.xls>. The spreadsheet contains volumetric time histories for eight (8) separate North Beach disposal events that are summarized in Appendix-A. The CEM was first run for these eight (8) events assuming the beach fill volumes were distributed using the standard 1:10 (rise over run) template laid out over an eroded basement surface that was specified by the 22 December 2014 profiles from Figures 1-4. These runs were used to establish a North Beach baseline performance standard for average sand loss rate,dtdV/, and retention time, 0T . This baseline was then compared against a sensitivity analysis of the proposed composite cycloid-dune beach fill template to determine possible advantages of this new template design and establish the optimal beach fill volume for North Beach, given the limitations of: 1) its small wave-cut platform, and 2) intrinsically high longshore transport rates with negative divergence of drift in the presence of the prevailing west/northwest swell and wind waves. 5.2.1: Historic Sand Retention Baseline: The baseline CEM simulation results are plotted in Figure 32, showing average rate of loss of beach fill dtdV/ (red) and the retention time, 0T , (blue) as a function of the total beach fill volume,0V . Sand loss rates are scaled against the left hand axis in Figure 32, while retention time is plotted relative to the right hand axis. The solution points for the eight (8) historic North Beach dredge disposal events that occurred between 1998 and 2015 are plotted with star symbols that were subsequently connected by cubic spline fitting functions plotted as the red and blue colored lines. The cubic spline best fit curves in Figure 32 show a minimum in the sand loss rate for North Beach fill volumes near the critical mass critV = 79,471 yds3, which is the theoretical maximum carrying capacity of North Beach for supporting a beach profile in equilibrium. The theoretical minimum sand loss rate using the standard 1:10 (rise over run) beach fill template is dtdV/= 1,495 yds3/day. When beach fill volumes are less than critical mass, critVV0 , there is insufficient sand to establish an equilibrium profile. A beach is in its most stable state with an equilibrium profile, but North Beach has a prevailing negative divergence of drift so that when equilibrium cannot be achieved due to insufficient sand volume, sand loss rates increase. For example, the measured sand loss Figure 32: CEM simulation of average rate of loss of beach fill, dtdV/ (red, left hand axis), and the retention time, 0T , (blue, right hand axis), as a function of the total beach fill volume, 0V , for 8 historic North Beach dredge disposal events , 1998-2015. CEM solution points are plotted with star symbols that were connected by cubic spline fitting functions plotted as the colored lines. Simulations based on standard 1:10 (rise over run) beach fill template assumption. rates during the 2014/2015 dredging event (where 0V = 64,968 yds3) were 32% higher than higher the theoretical minimum (theoretical minimum when critVV0 ). Consequently the retention time of 0T = 33 days during the 2014/2015 dredging event would have increased to 0T = 53 days if the beach fill volume placed on North Beach were increased from 0V = 64,968 yds3 to critVV0 = 79,471 yds3. Figure 32 also shows that retention time continues to increase as the disposal volume placed on North Beach exceeds the critical mass volume, but the sand loss rate also increases, which has a negative impact on the sand influx rates into Agua Hedionda Lagoon. For beach fill volumes above critical mass the improvement in retention time is minor, because the excess sand cannot be supported in equilibrium on the limited wave-cut platform, which is only 550 ft. to 600 ft. wide. The excess sand is quickly lost to the negative divergence of drift, (cf. Figures 30 b&c), after which an equilibrium profile can be established, once critVV0 . The initially high loss rate of the excess sand contributes to a higher average sand loss rates than what would have otherwise occurred if the beach fill volume were limited to the critical mass volume. Historically, what we find with the standard beach fill template, is that when beach fill sand volume is increased by 103% over critical mass (as occurred during the 2002/2003 dredge event when 0V = 161,525 yds3), the retention time retention time is only increased by 26 % from 0T = 53 days to 0T = 67 days. This is not a good return on doubling the investment in beach fill for North Beach because the sand loss rate increases by 61 % to dtdV/= 2,411 yds3/day, or an increase in sand loss of 916 yds3/day over what would have otherwise occurred if the beach fill volume were limited to critical mass. 5.2.2: Sand Retention with the Cycloid-Dune Template. The cycloid dune templates proposed in Figures 20-24 are tested in long-term CEM simulations using the same model calibration parameters and the same wave forcing and grain size inputs used in the historic baseline simulations. We also assume that the proposed cycloid-dune template is laid out over an eroded basement surface specified by the 22 December 2014 profiles from Figures 1-4, the same assumption was made for the baseline simulations. Because these cycloid-dune simulations are hypothetical, we do not limit ourselves to a mere handful of options for beach fill volumes, as was the constraint with the historic baseline simulations in Section 5.2.1. Instead, a sensitivity analysis is performed on beach sand loss rates and retention times using beach fill volumes that range from 0V = 36,000 yds3 to 0V = 175,000 yds3. The dune portion of the proposed templates in Figures 20-24 holds DV = 43,200 yds3 which were designed for a fill volume equal to the critical mass, critV = 79,471 yds3. For the modeling scenarios that involved less than critical mass, the dune portion of the template was proportionally reduced in volume until reaching the absolute minimum fill volume scenario of 0V = 36,000 yds3 , for which no dune component remains in the template. For the modeling scenarios where critVV0 , the dune portion of the template was proportionally increased in width until reaching the scenario of 0V = 175,000 yds3. Because we do not have historical guidance on the temporal beach fill placement for these hypothetical scenarios, we have made several additional assumptions. First, we assume that the beach fill is laid down at a constant daily rate of 4,500 yds3 per day on North Beach, which was the average daily placement rate in the dredge monitoring reports to the Regional Water Quality Control Board (Cabrillo, 2015) and in the Cabrillo Power Excel spreadsheet (< Dredge History.xls>). Secondly, we assume that the back-beach dune portion of the composite cycloid- dune template is built first, starting at the north inlet jetty and adding sections to the dredge pipeline until the build-out of the dune reaches Maple Ave. Building the dune first creates a “safe” reservoir of sand before the template can be fully constructed, and sand from this reservoir is only released to the lower eroded basement surface during periods of the highest tides and waves. After the buildout of the dune to Maple Ave, the cycloid portion of the template is laid out beginning from the toe of the dune and spreading the material to down slope to MLLW, and working back towards the north inlet jetty, removing pipeline sections as the cycloids are completed. CEM beach evolution simulations were performed on eighteen (18) different disposal scenarios involving cycloid-dune beach fill placement on North Beach ranging from 0V = 36,000 yds3 to 0V = 175,000 yds3. Each cycloid-dune scenario was repeated 8 times using start dates and wave forcing corresponding to the eight (8) historic North Beach dredge disposal events listed in Appendix A. Selecting these specific start dates in the wave record in Figure 13 eliminates the randomness effects of the historic occurrence of extreme waves, and allows for direct comparisons with the results of the historic baseline in Section 5.2.1. Sand loss rates and retention times for the 8 separate outcomes of each scenario were ensemble averaged to produce the points plotted as crosses in Figure 33, and these solution points were then fitted to cubic splines (plotted in red for sand loss rates relative to the left hand axis; and plotted in blue for retention time relative to the right hand axis). Sand loss rates were calculated from lofting the beach surfaces in SolidWorks 3-D CAD at a given time, itt, during the CEM beach evolution simulations. The mass properties tool in SolidWorks was used to calculate the volume change between the beach surface at itt and the pre-disposal basement surface (represented by the 22 December 2014 surveys). An example of this procedure is illustrated by Figures 34 and 35 for the disposal scenario critVV0 = 79,471 yds3 at time it = 90 days. At 90 days into the CEM beach evolution simulation, the dune has been eroded and re-distributed by extreme wave runup at high tides, leaving a residual volume rV = 41,941 yds3 of sand remaining between the basement surface (silver) and the new beach surface (brown). The new beach surface at it = 90 days conforms closely to an elliptic cycloid profile. Given this residual sand volume the sand loss rate that has occurred between the start of the CEM simulation at 0tt and itt= 90 days is given by: 90 941,41471,79/ 0 0  tt VVdtdV i rtti = 417 yds3/day (14) This gives an estimate of retention time (at it = 90 days) of )941,41471,79( 90471,79 )/(0   itt crit dtdV VT = 190.6 days (15) Four such SolidWorks loftings of the CEM beach surfaces were done at four different times, 432,,,tttttii, during each of the 18 scenario simulations, and the sand loss rates and retention Figure 33: Sensitivity analysis of average rate of loss of beach fill dtdV/ (red, left hand axis) and the retention time, 0T , (blue, right hand axis) as a function of the total beach fill volume, 0V , using the proposed cycloid-dune templates (cf. Figures 20-24 ). Each solution point (crosses) is an ensemble average of 8 modeled outcomes coinciding with the timing of historic North Beach dredge disposal events, relative to the wave forcing in Figure 11. Figure 34: Three-dimensional CAD model of two overlaid surfaces on North Beach, 1) the beach surfaces on North Beach after waves re-work 79,471 yds3 of cycloid-dune beach fill, (brown) at t = +90 days post-dredge disposal; and 2) the bottom of the critical mass envelope or basement surface (as delineated in silver from the 22 December 2014 profile measurements). CAD model shown with 10 to 1 vertical exaggeration Figure 35: Cross-section of 3-D CAD model of two overlaid surfaces on North Beach, 1) the beach surfaces on North Beach after waves re-work cycloid-dune beach fill, (brown) at t = +90 days post-dredge disposal; and 2) the bottom of the critical mass envelope (as delineated in silver from the 22 December 2014 profile measurements). CAD model shown with 10 to 1 vertical exaggeration. times calculated at each of those times were ensemble averaged to give the points and cubic spline curves plotted in Figure 33. While an elliptic cycloid is an equilibrium beach surface, it does not produce a state of zero sand loss in the presence of a negative divergence of drift, which is the persistent littoral drift state along North Beach. Recall from Section 5.0 that when the divergence of drift is negative (because less sand fluxes into North Beach at Maple Ave than is expelled from the North Beach at the inlet jetties, cf. Figure 30c), then the equilibrium cycloidal beach profile will shift landward, eventually intersecting the basement surface of the critical mass envelope, (i.e., the 22 December 2014 profile). Once this happens, then the cycloidal shape of the profile is disrupted, and the equilibrium state of the profile is lost. The concept behind the cycloid-dune template is that, as the cycloid approaches an intersection with the basement surface of the critical mass envelope, (under the erosional effects of continued negative divergence of drift), it also intersects the base of the dune and receives additional sediment cover as the dune erodes and spreads out downslope across the still intact cycloidal surface. So, the dune acts as a restoring mechanism that re-supplies the cycloid with sand lost to negative divergence of drift. Comparing the results in Figure 33 against the historic baseline in Figure 32, the general trends are similar, but the sand loss rates are greatly diminished and retention times significantly increased by using the proposed cycloid-dune template (in Figures 20-24). Again, the most efficient use of Agua Hedionda Lagoon dredged sands occurs when the cycloid-dune template is filled to no more than critical mass (critVV0 = 79,471 yds3), which reduces average sand loss rates on North Beach to an absolute minimum of dtdV/= 417 yds3/day, while extending retention time to 0T = 190.6 days. This is a 3.6 fold improvement in sand retention time over historical dredge disposal practices at North Beach, which could result in a reduction of sand influx rates into Agua Hedionda Lagoon by a similar factor during the months following North Beach disposal. If the cycloid-dune template is filled to more than critical mass (critVV0 ) by adding more sand to the back-beach dune, then North Beach retention time will increase beyond 190.6 days and reach as much as 0T = 222 days if the reserve sand volume in the dune were more than doubled to DV = 95,529 yds3 (achieving a total placement volume of 0V = 175,000 yds3). But, again, this is not a good return on doubling the investment in reserve beach fill for North Beach because retention time is only increased by an extra month while the sand loss rate increases by 89 % to dtdV/= 787 yds3/day, with proportionally higher sand influx rates into Agua Hedionda Lagoon for about 7 months post-North Beach disposal. Furthermore, it is simply not possible to place more sand than the critical mass in the back beach dune and not have much of the dune sand prematurely erode during periods of high waves and high tides, because the enlarged dune encroaches further seaward. Once eroded the excess dune sands that spill out across the active cycloid portion of the beach profile cannot be supported in equilibrium on the limited wave-cut platform, which is only 550 ft. to 600 ft. wide. On the other hand, under-filling the cycloid-dune template (critVV0 ) with a reduced dune, leads to accelerated sand loss rates and reduced retention times. The prevailing negative divergence of drift causes the initial cycloid profile in the lower portion of the template to shift landward, and once intersection with the basement surface of the critical mass envelope occurs, there is insufficient sand reserves in the reduced dune to resupply the cycloid in the presence of continued negative divergence of drift. Once the reserve sand supply in the dune is exhausted, the cycloidal shape of the profile is disrupted, and the equilibrium state of the profile is lost. Even so, Figure 33 shows that if the cycloid-dune template is filled to a volume equivalent to the 2104/2015 North Beach disposal event (0V = 64,968 yds3) by using a dune containing only DV = 28,697 yds3 , then sand retention times are still significantly better than what was achieved using the standard 1:10 (rise over run) template. With the cycloid-dune template, retention times for 0V = 64,968 yds3 of beach fill were 0T = 117 days and sand loss rates were reduced to dtdV/= 554 yds3/day, or a factor of 2.2 better than what was achieved using standard North Beach disposal practices during the 2104/2015 dredge event. With even smaller beach fill volumes, the cycloid-dune retention times and sand loss rates rapidly degrade, but retention times remain equivalent to those of the 2104/2015 North Beach disposal event for beach fill volumes as low as 0V = 37,000 yds3, for which the back beach dune was reduced to vanishingly small (DV 1,000 yds3). 6) Summary and Conclusions: A detailed set of beach profile surveys at North Beach in Carlsbad CA were provided by NRG Cabrillo Power Operations Inc delineating beach surfaces before and after the 2104/2015 dredging of Agua Hedionda Lagoon, which placed 64,968 yds3 between Maple Avenue and the north inlet jetty to Agua Hedionda Lagoon. The surveys were accurately performed by Nobel Engineers using differential GPS and known historic benchmarks. Three-dimensional CAD models were lofted from the measured points along the 4 North Beach survey range lines (Cab I-07 – Cab I-10) to delineate the beach surfaces immediately before North Beach dredge disposal (based on the 22 December 2014 profile measurements) and immediately after dredge disposal (based on the 17 April 2017 profile measurements). When these two surfaces were lofted together in a common reference frame, it was determined that 13,780 cubic yards of beach fill have been retained after placing 64,968 cubic yards on North Beach between 23 March 2015 and 15 April 2015. This calculates to an average sand loss rate of 1,969 yds3/day and projects a sand retention time for the entire fill volume of only 33 days. To understand the reasons for the poor sand retention characteristics of North Beach, a baseline beach evolution study was conducted using the Coastal Evolution Model (CEM) to hindcast the fate of beach fill placed on North Beach. The CEM was developed at the Scripps Institution of Oceanography with a $1,000,000 grant from the Kavli Foundation, (see http://repositories.cdlib.org/sio/techreport/58/ ), and is based on latest thermodynamic beach equilibrium equations published in the Journal of Geophysical Research. Inputs to the CEM baseline study were based on measured shoaling wave data, grain size data for the dredged sands, and daily beach fill volumes were derived from the dredge monitoring reports to the Regional Water Quality Control Board (Cabrillo, 2015) and from an Cabrillo Power dredging data base. Between 1998 and 2015 there have been eight (8) different events when Agua Hedionda dredged sands have been disposed as beach fill on North Beach. Historic dredged sand volumes placed on North Beach ranged from 62,030 yds3 to 161,525 yds3. The CEM beach evolution simulations of these events determined that the minimum in the sand loss rate occurs when North Beach fill volumes equal to the critical mass critV = 79,471 yds3, which is the theoretical maximum carrying capacity of North Beach for supporting a beach profile in equilibrium. The carrying capacity of a beach is limited by the width of the wave-cut platform in the bedrock on which beach sands have accumulated over geologic time scales. The wave-cut platform at North Beach is only 550 ft. to 600 ft. in width. Many of the beaches throughout north San Diego County are perched on narrow wave-cut platforms. The platforms are narrow because they were carved by wave action into erosion resistant bedrock formations during the present high-stand in sea level, and these narrow wave-cut platforms physically cannot hold large quantities of beach sand; and often become fully denuded during periods of high-energy winter waves. Another contributing factor to the limited carrying capacity of North Beach is that it is exposed to a prevailing negative divergence of drift caused by the way the bathymetry surrounding the Carlsbad Submarine Canyon influences wave shoaling at the southern end of North Beach.. The presence of the Carlsbad Submarine Canyon creates a bright spot in the shoaling wave pattern immediately north of the inlet jetties, where wave heights are locally higher than further to the North around Maple Avenue. The prevailing littoral drift transports beach sand southward throughout the entire Oceanside Littoral Cell; but at North Beach, the alongshore imbalance in wave height causes higher southerly longshore transport rates of sand exiting North Beach at the inlet jetties than enters North Beach at Maple Avenue. This inequality in sand transport rates between the north and south ends of North Beach is divergence of drift, and when the sand transport rates are higher at the down-drift end of the beach, it becomes a constant loss system referred to as negative divergence of drift. So, when beach fill volumes exceed the critical mass of North Beach, the excess sand cannot be supported in equilibrium on its narrow wave-cut platform and is quickly lost to the negative divergence of drift. Historically, The CEM baseline study finds that when a standard 1:10 (rise over run) beach fill template is filled to critical mass, the theoretical minimum sand loss rate to negative divergence of drift is 1,495 yds3/day, and the sand retention time is 53 days. When beach fill sand volume is increased by 103% over critical mass (as occurred during the 2002/2003 dredge event when 161,525 yds3 were placed on North Beach), the retention time is only increased by 26 % from 0T = 53 days to 0T = 67 days. This is not a good return on doubling the investment in beach fill for North Beach because the sand loss rate increases by 61 % to 2,411 yds3/day, or an increase in sand loss of 916 yds3/day over what would have otherwise occurred if the beach fill volume were limited to critical mass. Unfortunately, such increases in sand loss at North Beach correlate with proportional increases of sand influx rates into Agua Hedionda Lagoon. The 2014/2015 survey data show that AHL sand influx rates also increase when the fill volumes are less than the critical mass. Sand influx rates in 2014/2015 were 1,969 yds3/day when only 64,968 cubic yards were placed on North Beach (14,503 yds3 below critical mass requirements). Bear in mind that the critical mass is the minimum volume of sand required to establish an equilibrium beach profile on a wave-cut platform; and a beach is in its most stable state with an equilibrium profile. But with a prevailing negative divergence of drift along North Beach equilibrium cannot be achieved due to insufficient sand volume, and consequently sand loss rates increase with a destabilized non-equilibrium profile. The worst example of this in the CEM baseline was the 2010/2011 dredging event when only 62,030 yds3 were placed on North Beach, and sand loss rates rose to 2,050 yds3/day with retention times of only 30 days. Following CEM beach evolution analysis of the North Beach historic baseline, attention was given to finding a more effective beach fill template that could increase sand retention using beach fill from Agua Hedionda Lagoon dredging. Beach fill has typically been placed on Carlsbad beaches using a standard beach fill template with a flat backshore platform and a 1:10 (rise over run) seaward facing beach slope extending down to 0 ft. MLLW. This convention dates back to the Regional Beach Sand Project, (AMEC, 2002). However, stable beach profiles in Nature have a much more gradual, curving profile with slopes that range between 1:50 to 3:100. Formulations of equilibrium beach profiles are found in the U.S. Army Corps of Engineers Shore Protection Manual and later the Coastal Engineering Manual; and the latest most advanced formulation is known as the elliptic cycloids. The elliptic cycloid formulation can account for continuous variations in the equilibrium beach profile due to variability in wave height, period and direction when occurring in combination with variations in beach sediment grain size and beach sand volume. Therefore, a new beach fill template has been proposed here for North Beach referred to as the cycloid-dune template (see Figures 20-24). The shape of the template is based on the extremal elliptic cycloid which is the equilibrium profile for the highest wave in the period of record. But the extremal elliptic cycloid extends below the MLLW tide line and earth moving equipment which spread out the beach fill cannot work below MLLW. So, the template truncates the extremal elliptic cycloid at MLLW and places the residual volume of critical mass (totaling 43,200 yds3) in a back-beach dune that stretches 3,200 ft. from the Agua Hedionda Lagoon north inlet jetty to Maple Avenue. While an elliptic cycloid is an equilibrium beach surface, it does not produce a state of zero sand loss in the presence of a negative divergence of drift, which is the persistent littoral drift state along North Beach. When the divergence of drift is negative, the equilibrium cycloidal beach profile will progressively shift landward as it loses sand to negative divergence of drift, eventually intersecting the basement surface of the critical mass envelope. Once this happens, then the cycloidal shape of the profile is disrupted, and the equilibrium state of the profile is lost. The concept behind the cycloid-dune template is that, as the cycloid begins to approach an intersection with the basement surface of the critical mass envelope, (under the erosional effects of continued negative divergence of drift), it also intersects the base of the dune and receives additional sediment cover as the dune erodes and spreads out downslope across the still intact cycloidal surface. Thus, the dune acts as a restoring mechanism that re-supplies the cycloid with sand lost to negative divergence of drift. The construction method envisioned for the cycloid-dune template begins with building the back-beach dune portion first, starting at the north inlet jetty and adding sections to the dredge pipeline until the build-out of the dune reaches Maple Ave. Building the dune first creates a “safe” reservoir of sand before the template can be fully constructed, and sand from this reservoir is only released to the lower eroded basement surface during periods of the highest tides and waves. After the buildout of the dune to Maple Ave, the cycloid portion of the template is laid out beginning from the toe of the dune and spreading the material down slope to MLLW, and working back towards the north inlet jetty, removing pipeline sections as the cycloids are completed CEM beach evolution simulations of the cycloid-dune template show significant improvements in sand loss rate and retention time relative to the historic baseline. Again, the most efficient use of Agua Hedionda dredged sands occurs when the cycloid-dune template is filled to no more than critical mass (79,471 yds3), which reduces average sand loss rates on North Beach to an absolute minimum of 417 yds3/day, while extending retention time to 190.6 days. This is a 3.6 fold improvement in sand retention time over historical dredge disposal practices at North Beach, which could result in a reduction of sand influx rates into Agua Hedionda Lagoon by a similar factor during the first six (6) months following North Beach disposal. If the cycloid-dune template is filled to more than critical mass by adding more sand to the back-beach dune, then North Beach retention time will increase beyond 190.6 days. If the reserve sand volume in the dune were more than doubled to 95,529 yds3 (achieving a total placement volume of 0V = 175,000 yds3) then retention time could be extended to a maximum of 222 days. But, again, this is not a good return on doubling the investment in reserve beach fill for North Beach because retention time is only increased by an extra month while the sand loss rate increases by 89 % to 787 yds3/day. Furthermore, it is simply not possible to place more sand than the critical mass in the back beach dune and not have much of the dune sand prematurely erode during periods of high waves and high tides, because the enlarged dune encroaches further seaward into the middle bar-berm portion of the profile that is subject to more frequent wave attack. On the other hand, under-filling the cycloid-dune template, (by building a reduced dune), leads to accelerated sand loss rates and reduced retention times. The prevailing negative divergence of drift causes the initial cycloid profile in the lower portion of the template to shift landward, and once intersection with the basement surface of the critical mass envelope occurs, there are insufficient sand reserves in the reduced dune to resupply the cycloid in the presence of continued negative divergence of drift. Once the reserve sand supply in the dune is exhausted, the cycloidal shape of the profile is disrupted, and the equilibrium state of the profile is lost. Even so, if the cycloid-dune template is filled to a volume equivalent to the 2104/2015 North Beach disposal event (0V = 64,968 yds3) by using a dune containing only 28,697 yds3 , then sand retention times are still significantly better than what was achieved using the standard 1:10 (rise over run) template. With the cycloid-dune template, retention times with only 64,968 yds3 of beach fill were 0T = 117 days and sand loss rates were still small, 554 yds3/day, or a factor of 2.2 better than what was achieved using standard North Beach disposal practices during the 2104/2015 dredge event. With even smaller beach fill volumes, the cycloid-dune retention times and sand loss rates rapidly degrade, but retention times remain equivalent to those of the 2104/2015 North Beach disposal event for beach fill volumes as low as 37,000 yds3, for which the back beach dune was reduced to vanishingly small. 7) References: AMEC, 2002, “Regional Beach Sand Project Post-construction Monitoring Report for Intertidal, Shallow Subtidal and Kelp Forest Resources”, submitted to SANDAG, http://www.sandag.org. Cabrillo, 2015, ““Order 96-32: First Quarter 2105, Second Quarter 2015 and Final Monitoring Report for Agua Hedionda Lagoon Dredging”, submitted to California Regional Water Quality Control Board, 30 pp. CDIP, 1984-1988, "Coastal data information program, monthly reports," U. S. Army Corps of Engineers, California Department of Boating and Waterways, Monthly Summary Reports #97-#150. CDIP, 1976-1995, "Coastal Data Information Program, Monthly Reports," U. S. Army Corps of Engineers, California Department of Boating and Waterways, SIO Reference Series, 76- 20 through 95-20. CDIP, 1993-1994, "Monthly Summary Report," SIO Reference Series (93-27) through (94-19). CDIP, 2016, “Coastal Data Information Program” http://cdip.ucsd.edu/ Elwany, M. H. S., A. L. Lindquist, R. E. Flick, W. C. O’Reilly, J. Reitzel and W. A. Boyd, 1999, “Study of Sediment Transport Conditions in the Vicinity of Agua Hedionda Lagoon,” submitted to California Coastal Commission, San Diego Gas & Electric, City of Carlsbad. Elwany, M. H. S., R. E. Flick, M. White, and K. Goodell, 2005, “Agua Hedionda Lagoon Hydrodynamic Studies,” prepared for Tenera Environmental, 39 pp. + appens. Ellis, J.D., 1954, “Dredging Final Report, Agua Hedionda Slough Encina Power Station,” San Diego Gas and Electric Co., 44pp. Inman, D. L. and B. Brush, 1970, “The coastal challenge” Science, vol38, no. 5 pp36-45. Inman, D. L. & S. A. Jenkins, 1985, “Erosion and accretion waves from Oceanside Harbor,” p. 591-593, in Oceans '85: Ocean Engineering and the Environment, IEEE and Marine Technology Society, v. 1, 674 pp. Inman, D. L. and Masters, P. M., 1991, "Coastal sediment transport concepts and mechanisms," Chapter 5 (43 pp.) in State of the Coast Report, San Diego Region, Coast of California Storm and Tidal waves Study, U. S. Army Corps of Engineers, Los Angeles District Chapters 1-10, Appen. A-I, 2 v. Inman, D. L., M. H. S. Elwany and S. A. Jenkins, 1993, “Shorerise and bar-berm profiles on ocean beaches,” Jour. Geophys. Res., v. 98, n. C10, p. 18,181-199. Inman, D. L., S. A. Jenkins, and M. H. S. Elwany, 1996, “Wave climate cycles and coastal engineering practice,” Coastal Eng., 1996, Proc. 25th Int. Conf.,(Orlando), Amer. Soc. Civil Eng., Vol. 1, Ch. 25, p. 314327. Inman, D. L. & S. A. Jenkins, 1997, “Changing wave climate and littoral drift along the California coast,” p. 538-549 in O. T. Magoon et al., eds., California and the World Ocean '97, ASCE, Reston, VA, 1756 pp Inman, D. L. & S. A. Jenkins, 1999, “Climate change and the episodicity of sediment flux of small California rivers,” Jour. Geology, v. 107, p. 251270. Inman, D. L. & S. A. Jenkins, 2004, “Scour and burial of objects in shallow water,” p. 10201026 in M. Schwartz, ed., Encyclopedia of Coastal Science, Kluwer Academic Publishers, Dordrecht, Netherlands. Jenkins, S. A. and D. W. Skelly, 1988, "An Evaluation of the Coastal Data Base Pertaining to Seawater Diversion at Encina Power Plant Carlsbad, CA," submitted to San Diego Gas and Electric, Co., 56 pp. Jenkins, S. A., D. W. Skelly, and J. Wasyl, 1989, "Dispersion and Momentum Flux Study of the Cooling Water Outfall at Agua Hedionda," submitted to San Diego Gas and Electric, Co., 36 pp. + appens. Jenkins, S. A. and J. Wasyl, 1993, "Numerical Modeling of Tidal Hydraulics and Inlet Closures at Agua Hedionda Lagoon," submitted to San Diego Gas and Electric, Co., 91 pp. Jenkins, S. A. and J. Wasyl, 1994, "Numerical Modeling of Tidal Hydraulics and Inlet Closures at Agua Hedionda Lagoon Part II: Risk Analysis," submitted to San Diego Gas and Electric, Co., 46 pp. + appens. Jenkins, S. A. and J. Wasyl, 1995, "Optimization of Choke Point Channels at Agua Hedionda Lagoon using Stratford Turbulent Pressure Recovery," submitted to San Diego Gas and Electric, Co., 59 pp. Jenkins, S. A. and J. Wasyl, 1997, "Analysis of inlet closure risks at Agua Hedionda Lagoon, CA and potential remedial measures, Part II," submitted to San Diego Gas and Electric, Co., 152 pp. + appens. Jenkins, S. A. and J. Wasyl, 1998a, Analysis of Coastal Processes Effects Due to the San Dieguito Lagoon Restoration Project: Final Report, submitted to Southern California Edison Co., 333 pp. Jenkins, S. A. and J. 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Wasyl, 2011, “Hydrodynamic Approach to Wetland Restoration by Optimization of Bridge Waterways”, Department of Transportation, District 11 Environmental Division, MS-242, Technical Report # 11A1766, 258 pp. Jenkins, S. A. and S. Taylor, 2015, “Storm and Tidal Conditions Determination for Coastal Drainage Design,” submitted to Office of Highway Drainage Design Division of Design, MS 28, California Department of Transportation Merkel, 2008, “ Agua Hedionda Outer Lagoon Flood Shoal Maintenance Dredging Sediment Characterization Report, Tech Rpt # ACOE-2001100328-SKB, submitted to Cabrillo Power, LLC., 45 pp. NOAA, 1998, AVerified/Historical Water Level Data@ http://www.opsd.nos.noaa.gov/data_res.html NWS, 2009, “National Weather Service Daily Climate Reports,” http://www.wrh.noaa.gov/sgx/obs/rtp/carlsbad.html U.S. Army Corps of Engineers, 1985, “Littoral zone sediments, San Diego Region, October 1983 – June 1984”, Coast of California Storm and Tidal Wave Study, CCSTWS 85-11. U. S. Army, Corps of Engineers (USACE), 1991, “State of the Coast Report, San Diego Region,” Los Angeles District, CA: Coast of California Storm and Tidal Waves Study, Final Report 1. U. S. Army, Corps of Engineers (USACE), 2006, “Coastal Engineering Manual,” Engineering Manual 1110-2-1100, U. S. Army, Corps of Engineers, Washington, DC, (in 6 volumes). U.S. Department of Commerce National Ocean Service, 1986, “Tide tables 1986, high and low water predictions for west coast of North and South America”, 234 pp. USGS, 1997, "USGS Digital Data Series DDS-37 at INTERNET URL," http://wwwrvares.er.usgs.gov/wgn96cd/wgn/wq/region18/hydrologic unit code. Van der Meer, J.W., 2002. Wave Run-up and Overtopping at Dikes. Technical Report, Technical Advisory Committee for Water Retaining Structures (TAW), Delft, the Netherlands. Appendix-A: North Beach Disposal History for Agua Hedionda Outer Lagoon Year Dredging Disposal Comments Date Volume cubic yard Influx Basin Volume cubic yard *Location Start Finish Days Yds3/Day 1998 Dec-97 Feb-98 59,072 92 642 Middle 59,072 M Modification Feb-98 Jul-98 214,509 150 1,430 Inner 120,710 M Modification 93,799 S 1999 Feb-99 May- 99 155,000 304 510 Outer 155,000 N Maintenance 2000- 01 Nov- 00 Apr-01 422,541 701 603 Outer 141,346 N Maintenance 195,930 M 85,265 S 2002-03 Dec-02 Apr-03 354,266 730 485 Outer 161,525 N Maintenance 131,377 M 61,364 S 2004-05 Jan-05 Mar-05 348,151 704 495 Outer 100,487 N Maintenance 170,515 M 77,149 S 2006- 07 Jan-07 Apr-07 333,373 763 437 Outer 149,168 N Maintenance 121,038 M 63,167 S 2008- 09 Dec-08 Apr-09 299,328 733 408 Outer 104,141 N Maintenance 102,000 M 93,185 S 2010-11 Dec-10 Apr-11 226,026 736 307 Outer 62,030 N Maintenance 93,696 M 70,300 S 2014-15 Dec-10 Apr-11 294,661 736 400 Outer 64,968 N Maintenance 156,056 M 73,637 S TOTAL 8,528,842 8,528,840 MAINTENANCE TOTAL 8,255,261 *Location: N= North Beach; M = Middle Beach; S = South Beach PROJECT NO. 1602-1331DATE: AUGUST 2017SHEET NO. 1 Pacific Ocean PROJECT LOCATION LEGEND: Proposed Dredging Limit (37.32 acres) Beach Deposit Area 0 1 2 Miles TITLE SHEET CABRILLO POWER I LLCENCINA POWER STATION FLOOD PLAIN SPECIAL USE PERMIT RENEWAL SUP 06-10-X2A LOCATION MAP: SHEET INDEX Source: NAIP 2014 Image, Noble Consultants 4/2015, Esri Online Basemap, SANDAGCoordinate System: NAD 1983 StatePlane California VI FIPS 0406 FeetNotes: This map was created for informational and display purposes only 0 75150 Feet MAP NOTES: C O A S T E R & A M T R A K R A I L MiddleBeach SouthBeach NorthBeach W A S H I N G T O N S T PARKDRCHINQUAPIN AVE C A R L S B A D B L V D H A R D I N G S T HOOVER STOAKAVECARLSBAD VILLAGE DRPALM AVEC A N N O N R DTAMARACKAVEH ARRIS ON STHI G H L A N D D R J A ME S D RCHESTNUTAVE G A R F I E L D S T PARKSI DEPLPINE AVEA I D A NC IRJEA NNEPL S T A T E S T LON G PLWALNUT AVEP O L L Y L N A D A I R W A Y A L L E Y O C E A N S T Y V E T T E WAY R O O S E V E L T S T V A L L E Y S T MAPLE AVEP RIV A T E R D T Y L E R S T ACACIA AVELI N C O L N S TGRAND AVECHERRY AVEA D A M S S T JUNIPER AVEHEMLOCK AVEM A D I S O N S T S Y MED RWO O D L A N D W A Y OLIVE AVEREDWOOD AVESEQUOIA AVEJ E F F E R S O N S T KA L P A T ICIR HIBIS C USCI R DATE AVESH O R E D R C A N A R I OSTPIO P ICO DRVIL LAG ECIRMAGNOLIA AVE H A R B O R D REUREKA PLA V E NID A E N CIN A S N A U TIC ALD RLI N M A R L N L O S R O B L E S D R BRADY CIR ANCHOR WAY E L A R B O L D RLAYANGLAYANGCIR HILLSIDEDR A G UILAS TPASEODELNORTEV IL L AG EDRTITLE SHEET SITE PLAN OUTER LAGOON BEACH PROFILES SHEET 1 SHEET 2 SHEET 3 SHEET 4 PROJECT LOCATION: PROJECT SITE ADDRESS: CABRILLO POWER I LLC ENCINA POWER STATION 4600 CARLSBAD BOULEVARD CARLSBAD, CA 92008-4301 PROJECT SITE PARCELS: APN: 2100104700, 2100104500 PROJECT SITE LOCATION DESCRIPTION: THE PROJECT SITE IS 37.32AC LOCATED FULLY WITHIN THE WATERS OF THE AGUA HEDIONDA LAGOON, WHICH IS WITHIN THE CITY LIMITS OF THE CITY OF CARLSBAD. THE PROJECT SITE IS LOCATED IN THE PORTION OF THE AGUA HEDIONDA LAGOON BETWEEN CARLSBAD BOULEVARD AND THE AMTRAK AND COASTER RAIL. GENERAL MAP NOTES: MAPS WERE PREPARED USING THE CITY OF CARLSBAD DEVELOPMENT PERMITS REQUIRED PLANS (REVISED 02/16) AS A GUIDE. EFFORTS WERE MADE TO MEET ALL CRITERIA LISTED IN THE REQUIRED PLANS, HOWEVER DUE TO THE NATURE OF THE PROJECT AND ITS TECHNICAL COMPLEXITIES, THE THREE SHEETS LISTED IN THE BELOW TABLE PROVIDE THE APPLICABLE PROJECT DETAILS AND INFORMATION. MAP SHEET INFORMATION: SITE PLAN: THE SITE PLAN SHEET DEPICTS: -PROPOSED DREDGING LIMITS -CURRENT BATHOMETRY -CROSS-SECTION LOCATIONS AND CROSS- SECTIONS SHOWING CURRENT AND PROPOSED BATHOMETRY -CROSS-SECTION LOCATIONS AND CROSS- SECTIONS SHOWING BEACH TOPOGRAPHY AND BATHOMETRY OVER TIME -RECENT AERIAL IMAGERY TO GIVE SITE SETTING CONTEXT -REGIONAL LOCATION OF THE PROJECT SITE OUTER LAGOON: THE OUTER LAGOON DEPICTS: -CROSS-SECTION LOCATIONS AND CROSS- SECTIONS SHOWING CURRENT AND PROPOSED BATHOMETRY -PROJECT, SURVEY AND REVISION HISTORY BEACH PROFILE: THE BEACH PROFILE SHEET DEPICTS: -CROSS-SECTION LOCATIONS AND CROSS- SECTIONS SHOWING BEACH TOPOGRAPHY AND BATHOMETRY OVER TIME -PROJECT, SURVEY AND REVISION HISTORY VICINITY MAP: 0 250 500 Feet C A R L S B A D B L V D C O A S T E R & A M T R A K R A I L - 3 3 -38 -39 -7 -1 4 -6-2-3-6 -3 3 12 -1 -3 -6 -3-7 -17 -19 -21 -13 -14 -16 -16 -17 -18 -19 -21 2 2 2 -3 - 4 -13 -14 - 1 6 1 -1 -1 -1 -2 -18 1 -1 -6 -6-1 4 -17-18-19 -2 1-21-21 -22 -23-8 -9 -11-13 -12-2-7-8 -13-7 -8 -2 -3 -4-22 1 - 1 -171 -1-2-2 -3 -4-4 -4 -6 - 1 3 -1632 -1 -1-2 -4 - 4 -4-6 -6-7-14-16-18-21 -21 -22-223 2 1 -1 -4 -21 -5 -5 -5 0 -5-20 -20 0 0 0 -5-150 -20 0 0 -5 -5 -15 -20 -20 -20-20 -5 -10-5-5 - 1 5 - 15 0 0 0- 5 -10 -1 5 -1 5 -15-15-15 -15-15 -15 -15 -20 -20 -20-2000 -5-5-5-5 -15 -15 -2 0-528+00 24+00 26+00 30+002+006+0022+004+008+0020+0010+0018+00 12+0014+0016+00Cab I-0 4 Cab I- 0 6 Cab I-0 5 MiddleBeach SouthBeach NorthBeach PROJECT NO. 1602-1331DATE: AUGUST 2017SHEET NO. 2 LEGEND: Beach Deposit Area Proposed Dredging Limit (37.32 acres) Beach Profile Transect Location Cross Section Location 5' Elevation Contour (feet, MLLW) 1' Elevation Contour (feet, MLLW) 0 1,500 3,000 Feet SITE PLAN CABRILLO POWER I LLCENCINA POWER STATION FLOOD PLAIN SPECIAL USE PERMIT RENEWAL SUP 06-10-X2A MiddleBeach SouthBeach NorthBeach Cab I-0 1 Cab I-0 2 Cab I-0 7 Cab I-0 9 Cab I-0 8 Cab I-1 0 Cab I-0 3 Cab I- 0 4 Cab I-0 5 Cab I-0 6 0 350 700 Feet REGISTERED CIVIL ENGINEER: CHIA-CHI LU, PH.D., P.E., D.CE.NOBLE CONSULTANTS 2201 DUPONT DRIVE, #830IRVINE, CA 92612-7509 (949) 752-1530 X 104 (PHONE) BEACH PROFILE TRANSECTS AND TRANSECT LOCATION MAP: REGIONAL LOCATOR MAP: CROSS SECTIONS: PROJECT PARCEL INFORMATION TABLE: Source: NAIP 2014 Image, Noble Consultants 4/2015, Esri Online Basemap, SANDAG, City of Carlsbad 2015 Zoning Map and 2013 Land Use MapCoordinate System: NAD 1983 StatePlane California VI FIPS 0406 FeetAbreviations:APN = assessor parcel number; ft = feet; MLLW = mean lower low waterNotes: This map was prepared using April 2015 survey data. The most recent previous revision was December 2014. For additional detail on basemap revision history, please see Agua Hedionda Outer Lagoon drawing dated April 2015 and Agua Hedionda Beach Profiles dated April 2015.This map was created for informational and display purposes only 0 75 150 Feet PROJECT CONTACT INFORMATION: MAP NOTES: OWNER/DEVELOPER:CABRILLO POWER I LLC ENCINA POWER STATION4600 CARLSBAD BOULEVARD CARLSBAD, CA 92008-4301760-268-4000 SHEET 3SUP06-10-X2A SHEET 4SUP06-10-X2A ATTACHMENT 3 nrg. Cabrillo Power I LLC 4600 Carlsbad Blvd. Carlsbad, CA 92008 (760) 268-4000 September 12, 2017 Ms. Pam Drew Planning Department City of Carlsbad 1635 Faraday Ave. Carlsbad, CA 92008 Re: Floodplain Special Use Permit Extension Request, SUP 06-10x2A Response to Planning Commission Comments and Questions Dear Ms. Drew, On September 6, 2017 Cabrillo Power I LLC (Cabrillo), an indirect wholly owned subsidiary of NRG Energy, Inc. (NRG), sought approval from the City of Carlsbad (City) Planning Commission (PC) of the extension of Special Use Permit (SUP) 06-10x2A for Outer Agua Hedionda Lagoon (AHL) Maintenance Dredging. As you know, the PC approved the continuance of the decision on the extension of SUP 06-10x2A to allow City Staff to gather additional information in response to interested community members who have requested that the City add a condition to the SUP addressing sediment toxicity testing associated with the dredging and deposition of dredge material on North, Middle, and South beaches. Cabrillo looks forward to addressing this topic during the PC's September 20th meeting to clarify the logistics for maintenance dredging, including a description of the associated agency permits and approvals, and to clarify the status of AHL with respect to sediment quality and historical toxicity testing. As a preview of that discussion, historical sediment toxicity analyses conducted on behalf of the San Diego Regional Water Quality Control Board (SDRWQCB) from 2003 through 2013 and historical chemical analyses of the Outer AHL dredge material (most recently in 2014 as part of the last dredge cycle) have demonstrated that the Outer AHL is not impaired by sediment toxicity. Furthermore, dredge material characterization is a condition of the United States Army Corps of Engineers (USACE) approval for the Outer AHL maintenance dredging; the required sampling and analysis plan includes analysis of inorganic and organic compounds that includes metals, volatile and semi-volatile organic compounds, polychlorinated biphenyls and pesticides from which sediment toxicity is assessed. Based on the scope and expertise of the USACE, we believe testing requirements for the maintenance dredge permit are properly conditioned in the USACE permit. To support the PC's request for City Staff to gather additional information pertaining to the status of AHL sediment quality, Cabrillo provides the following background information, which includes the description of AHL and the associated permitting and sampling requirements for the maintenance dredging. AHL is a tidal estuary open to the Pacific Ocean on the western ATTACHMENT 4 Ms. Pam Drew City of Carlsbad September 12, 2017 Page 2 boundary and fed by Agua Hedionda Creek (Creek) on the eastern boundary. The lagoon is separated into three basins: Inner is between the Creek delta and Interstate 5; Middle is between Interstate 5 and the North County Transit Railroad Bridge; and Outer is between the North County Transit Railroad Bridge and Carlsbad Boulevard. Each basin has its own ecology based on water source, depth, and resident biota. All three basins of AHL were dredged in 1954 to provide cooling water source to Encina Power Station. The outer basin of AHL has been maintenance dredged 29 times, since 1954. The majority of the sand removed in a dredge cycle has entered the Outer basin from the northerly Carlsbad beaches and the Pacific Ocean via the southbound littoral drift. It is a coarser grain size than the sediment located in the Inner basin. Analytical results from the 2014-2015 Outer basin dredge cycle confirm that the dredge material is coarse grain without appreciable fine grain sediment and that this grain size matches that of the receiving beach locations. Additionally, the chemical analyses of the dredge material indicated no inorganic and organic chemicals above toxicity thresholds.1 Cabrillo is subject to six (6) separate permits and their respective agencies. Following is a listing of these permitting agencies and the historically required environmental and engineering monitoring. These permits also contain numerous qualitative requirements for discharge water quality. Agency and Permit Number if current Monitoring Requirements United States Army Corps of Engineers SPL-2001-00328-RRS • • Sampling and Analysis per the Inland Testing Manual or the Ocean Disposal Manual (SAP) Grunion surveys depending on disposal season • Pre-dredge Caulerpa taxifolia survey per the Caulerpa Control Protocol • Pre- and Post-dredge Eelgrass survey per the Southern California Eelgrass Mitigation Policy • Pre- and Post- dredge Bathymetric Survey • Annual Reef Survey of all three beach segment areas California Coastal Commission Coastal • Requires September 15 to April 15 cycle Development Permit — Pending timing • Grunion monitoring • Pre- and Post-dredge Bathymetric survey • Pre- and Post-dredge Eelgrass survey • Pre-dredge Beach Profiles • Pre-dredge Caulerpa Taxifolia survey • Dredge Plan Ms. Pam Drew City of Carlsbad September 12, 2017 Page 3 Agency and Permit Number if current Monitoring Requirements Regional Water Quality Control Board • Weekly Turbidity during discharge WDR 96-32 — Applicability Pending • Weekly Total Coliform during discharge; should there be an exceedance of limitations, then monitoring goes to daily and San Diego County Department of Environmental Health is notified for potential beach closure • Daily spoils discharge logs California Department of Parks and Recreation • None Right of Entry Permit — pending California State Lands Commission Lease • None PRC 932.1 City of Carlsbad Special Use Permit • Dredge Plan, including pedestrian and SUP 06-10-x2A pending signage plan • Sand Deposition Plan • Pre-dredge Caulerpa Survey • Pre- and Post-dredge Eelgrass Survey • Compliance with storm water Best Management Practices To clarify the status of AHL with respect to sediment toxicity, the California State Water Resources Control Board (SWRCB) is required to comply with the Clean Water Act (CWA) conditions as they pertain to water quality in water bodies of the State. "CWA section 303(d) requires states to identify waters that do not meet, or are not expected to meet by the next listing cycle, applicable water quality standards after the application of certain technology- based controls and schedule such waters for development of Total Maximum Daily Loads (TMDLs) [40 Code of Federal Regulations (CFR) 130.7(c) and (d)r2 Per the 2012 303(d) list - the currently active list - AHL is not a listed water body for any pollutant.3 In July 2016 as part of the subsequent review and update of the 303(d) list, the SDRWQCB recommended to the SWRCB to list AHL for sediment toxicity based on studies conducted in 2003, 2004, 2005, and 2008.4 Eight samples were collected of which three samples indicated sediment toxicity above thresholds (i.e., less than 80% survival of targeted biological species exposed to the subject sediment samples). These three samples were collected from Inner AHL; five passing results were from samples collected from Middle and Outer AHL. In August 2016, Cabrillo sent comments to the SWRCB regarding the proposed listing of AHL and noted that sediment toxicity was not observed in the Outer AHL or the Middle AHL. Cabrillo also noted in its comment letter that based on the results of three sediment toxicity samples collected in 2013 from the Inner, Middle and Outer AHL, neither segment of AHL demonstrated sediment toxicity above thresholds (i.e., greater than 80% survival of target biological species was observed), which indicates improving sediment quality since the 2003 to 2008 sample events. Cabrillo therefore requested that SWRCB remove from consideration listing of AHL for sediment toxicity, but if the SWRCB further pursues a 303(d) listing for AHL, that the SWRCB Ms. Pam Drew City of Carlsbad September 12, 2017 Page 4 consider separating AHL into three basins for the purposes of 303(d) listing based on the significant ecological differences between the Inner, Middle, and Outer Agua Hedionda Lagoon basins.5 In the Draft Staff Report — 2014 and 2016 California Integrated Report Clean Water Act Sections 303(d) and 305(b), the SWRCB staff made the following recommendation for the listing of Agua Hedionda Lagoon for Sediment Toxicity: The data from this listing pre-dates the Sediment Quality Objectives and will be re- assessed in the future in accordance with the Sediment Quality Objectives which requires analysis of chemistry, toxicity and biological data. This waterbody may be divided into two segments, the eastern lagoon which is composed of the inner lagoon, and the western lagoon, which is composed of the outer and middle lagoons. This waterbody segmentation will be proposed for the next Listing Cycle based on an analysis of land use and hydrology consistent with Section 6.1.5.4 of the Listing Policy. The current impairment due to Toxicity in sediment is localized to the eastern portion of the lagoon. Data collected from the outer and middle portions of the lagoon do not indicate impairment.6 While the updated 303(d) listing for AHL has not been issued, Cabrillo asserts that the sediment characterization data from 2003 through 2013 and the evaluation of the SWRCB in the Draft Staff Report supports that Outer AHL has not been a source for sediment toxicity. Accordingly, any further requirements in the SUP for the maintenance dredging are not warranted. Based on the foregoing, the City should not add a condition into the extension of the SUP that requires sediment toxicity monitoring If you have any questions or concerns, please contact Ms. Sheila Henika, P.E. at (760) 268-4018 or sheila.henika@nrg.com. Sincerely, Cabrillo Power I LLC /4-er --47F-417 George L. Piantka, PE Sr. Director, Regulatory Environmental Services NRG Energy, West Region cc: Jerry Carter, Cabrillo Power I LLC Sheila Henika, NRG West Region Tim Sisk, NRG West Region Dave Gibson, San Diego Regional Water Quality Control Board Robert Smith, United States Army Corps of Engineers Erin Prahler, California Coastal Commission Ms. Pam Drew City of Carlsbad September 12,2017 Page 5 References: 1 Cabrillo Power I LLC, Agua Hedionda Lagoon Flood Shoal Maintenance Dredging Sediment Characterization Report; July 2014; Merkel & Associates, Inc. 2 Water Quality Control Policy for Developing California's Clean Water Act Section 303(d) List; State Water Resources Control Board; February 3, 2015; page 1; http://www.waterboards.ca.gov/board decisions/adopted orders/resolutions/2015/02031 5 8 amendment clean version.pdf 3 Impaired Water Bodies; http://www.waterboards.ca.gov/water issues/programs/tmdl/integrated2012.shtml 4 2014 Water Quality Assessment; http://www.waterboards.ca.gov/sandiego/water issues/programs/303d list/index.shtml 5 Letter to SWRCB by Cabrillo Power I LLC, dated August 12, 2016; 6 Draft Staff Report — 2014 and 2016 California Integrated Report Clean Water Act Sections 303(d) and 305(b); June 9, 2017; http://www.waterboards.ca.gov/water issues/programs/tmdl/integrated2014 2016/staff report integrated.pdfLand http://www.waterboards.ca.gov/water issues/programs/tmdl/integrated2014 2016/categ ory5 report.shtml rirg. Cabrillo Power I LLC 4600 Carlsbad Blvd. Carlsbad, CA 92008 (760) 268-4000 August 12, 2016 San Diego Regional Water Quality Control Board Attention: Xueyuan Yu 2375 Northside Dr., Suite 100 San Diego, CA 92108 Subject: Comment — CWA Section 305(b)/303(d) Integrated Report, Attn: Xueyuan Yu Ms. Yu, Cabrillo Power I LLC (Cabrillo) has reviewed the San Diego Regional Water Quality Control Board's (SD RWQCB) draft Clean Water Act Sections 305(b) and 303(d) Integrated Report for the San Diego Region (Integrated Report) dated July 2016. Cabrillo also attended the public workshop that provided an overview of the procedures used to develop the Integrated Report on July 19,2016. Cabrillo is the owner of the Agua Hedionda Lagoon (AHL) and discharges stormwater in accordance with its Industrial General Permit to the outer and middle basins of the AHL. Cabrillo discharges associated with the operation of the Emilia Power Station, in accordance to its individual Industrial National Pollutant Discharge Elimination Permit (NPDES) NO. CA0001350, are directed to a discharge basin connected to the ocean (i.e., direct ocean discharge). Cabrillo understands that the SD RWQCB has recommended listing the AHL on the 303(d) list for Toxicity based on sediment results from studies conducted in 2003, 2004, 2005 and 2008. Cabrillo understands the procedures followed in developing the Toxicity recommendation; however, we disagree with the recommendation and provide the following comments. Comment #1: Toxicity results 2003, 2004, 2005, and 2008 The AHL has been recommended to be added to the 303(d) list for "toxicity," and this is assumed to be sediment toxicity based on the results of the County of San Diego Ambient Bay and Lagoon Monitoring (ABLM) Project 2003-2005 — Chemistry, Pathogens, Toxicity and Benthic Infauna, and the San Diego County Municipal Copermittees Bight 2008 Sediment Chemistry, Toxicity and Benthic Infauna Data (08 Bight) studies. The two studies yielded eight unique results for sediment toxicity for four years of testing over a six year period. Of the eight results, three tests reported survival endpoints below 80 percent and five results reported greater than 80 percent. The Draft 303(d) Fact Sheet provides the AHL summary of the Line of Evidence (LOE) for toxicity as record 47577, and LOE' s 72909 for the 08 Bight study and 72914 for the ABLM study. LOE 72909 reports five samples with one toxicity exceedance. LOE 72914 reports three samples with three exceedances. The data were reviewed in the referenced reports and is summarized in the following tables. As mentioned above, the exceedance criteria is considered survival endpoints of less than 80 percent (State Water Resource Control Board, June 2012); however, the ABLM report has only two results below 80 Page 1 of 4 percent and one result above 80 percent. Cabrillo recommends revising the LOB records 47577 to reflect three of eight samples reporting exceedances, and LOB 72914 to reflect two of three samples reporting exceedances. County of San Diego Ambient Bay and Lagoon Monitoring (ABLM) Project 2003-2005 — Chemistry, Pathogens, Toxicity and Benthic Infauna Lagoon Station Code Latitude Lon gitude Portion of the AHL Sample Composite Identification 904_AHL2M_2003 33.14337 -117.33153 Inner lagoon 904AHL_2003 904 AHL3L 2003 33.13972 -117.32448 Inner lagoon 904AHL_2003 904 AHL3M_2003 33.14092 -117.32435 Inner lagoon 904AHL 2003 904 AH L2 L2_2004 33.14169 -117.33084 Inner lagoon 904AHL 2004 904_AHL3L1 2004 33.13990 -117.32367 Inner lagoon 904AHL_2004 904 AHL3R1 2004 33.13968 -117.31826 Inner lagoon 904AHL 2004 904_AHL3L1_2005 33.14028 -117.32638 Inner lagoon 904AHL_2005 904_AHL3M1 2005 33.14228 -117.32652 Inner lagoon 904AHL_2005 904 AHL3R1 2005 33.14230 -117.32293 Inner lagoon 904AHL_2005 ABLM Toxicit Results Lagoon Station Code Toxicity Results Portion of the AHL 904AHL 2003 45% Inner lagoon 904AHL_2004 85% Inner lagoon 904AHL_2005 62% Inner lagoon San Diego County Municipal Copermittees Bight 2008 Sediment Chemistry, Toxicity and Benthic Infauna Data (08 Bight) Lagoon Station Code Latitude Longitude Toxicity Results Portion of the AHL 904_6269 33.13925 -117.33775 83% Outer Lagoon 904_6270 33.13962 -117.31861 92% Inner lagoon 904_6271 33.14016 -117.3251 61% Inner lagoon 904_6280 33.14456 -117.32811 81% Inner lagoon 904_6282 33.1451 -117.33565 87% Middle Lagoon Comment #2: Toxicity Evaluation The State Water Quality Control Policy for Developing California's Clean Water Act 303(d) List (Policy) (State Water Resources Control Board, September 2004), section 6.1.1 states that the RWQCBs should consider all readily available data when making a determination. The Policy section 6.1.5.3 also states that, "If the implementation of a management practice(s) has resulted in a change in the water body segment, only recently collected data [since the implementation of the management measure(s)] should be considered." The most recent sediment toxicity testing of the AHL was performed in 2013 and reported in December 2015 (SCCWRP Technical Report 899, December 2015). The results of the testing reported three results for AHL. One sample was collected from the outer lagoon and two samples from the inner lagoon. All samples reported greater than 80 percent survival. In addition, the 2015 evaluation methodology meets the requirements of California's sediment quality objectives (SQ0) policy for bays and estuaries (Draft Proposed Amendments to the Water Quality Control Plan for Enclosed Bays and Estuaries Plan, Part I: Sediment Quality, SWRCB, January 2011) for having both short term survival and sublethal toxicity evaluation methods. The 2015 study used both Eohaustorius Page 2 of 4 estuaries and Mytilus galloprovincialis species to test each sample. The previous studies only used Eohaustorius estuaries to determine toxicity. Considering that the ABLM and 08 Bight studies were performed over a six year period, and when combined with the most recent 2013 results (decade temporal range), the cumulative data set may indicate improving sediment quality (Policy section 3.10). It is also Cabrillo's understanding that ideally, sediment toxicity be associated with a specific pollutant (Policy section 3.6); however, we acknowledge that a water body can be listed for toxicity alone. Based solely on the results of the ABLM and 08 Bight studies, there does not seem to be any association or correlation with a specific pollutant that would explain the toxicity observed in both studies. In addition, recent changes in State policies for banning the use of certain pesticides, improved storm water runoff programs (new General Permits for industrial and construction storm water runoff), and the recent local management plan aimed at improving water quality and habitat in the Agua Hedionda watershed (City of Vista, 2008), Cabrillo requests that the SD RWQCB consider postponing the addition of AHL to the 303(d) list for sediment toxicity. Comment #3 AHL Water Body Description and Beneficial Uses The AHL is described in the Water Quality Control Plan for the San Diego Basin (Basin Plan) Region describes as, "Agua Hedionda Lagoon, at the mouth of Agua Hedionda Creek, is within the city of Carlsbad. The lagoon is routinely dredged to keep it open to the ocean. The lagoon Serves as an integral part of a utility's power plant cooling water intake system and also provides a reserve cooling water supply. The easterly portion of the lagoon is used for water oriented recreation." The AHL is listed as having the following uses: industrial (IND), contact and non- contact recreation 1 and 2 (REC1 and REC2), commercial and sport fishing (COMM), biological habitats of special significance (BIOL), estuary (EST), wildlife habitat (WILD), rare species habitat (RARE), marine (MAR), aquaculture (AQUA), migration of aquatic organisms habitat (MIGR), spawning and reproduction habitats (SPWN), and shellfish harvesting area (SHELL). The AHL comprises approximately 247 acres consisting of three distinct lagoon areas. The outer lagoon is approximately 52 acres, the middle lagoon is approximately 19 acres, and the inner lagoon is approximately 176 acres. The lagoon areas are connected by narrow channels that run under major transportation corridors. All three basins of the AHL experience tidal influence, and to a lesser extent drainage from the Agua Hedionda Creek. Each of these portions of the AHL has different physical characteristics (tidal flushing and receiving waters) and uses. The outer lagoon currently supports the industrial uses for power plant intake of once- through cooling water, and desalination plant intake; and shellfish harvesting; and commercial fishery; and public access is restricted. Dredging of the outer lagoon is expected to continue to occur periodically, as needed, to maintain the power plant cooling and desalination plant intake systems. The dredging occurs in the most outer lagoon. The outer lagoon receives storm water runoff from the Encina Power Station western facilities, and runoff from the various City of Carlsbad streets and open areas, surrounding businesses. The middle lagoon is used for recreational contact and non-contact recreational activities (sporty fishing, YMCA Camp, etc.) with public access. The middle lagoon receives Page 3 of 4 storm water runoff from the Carlsbad Energy Center Project site (eastern portion of the BPS), the City of Carlsbad sewer lift station, Caltrans 1-5 freeway, and the North County Transit District (NCTD) rail facility. • The inner lagoon is utilized for contact and non-contact recreation and sport fishing with several public access points. The inner lagoon receives surface water from the Agua Hedionda Creek at the eastern end of the lagoon, and storm water runoff from various City of Carlsbad storm drains and the Caltrans 1-5 freeway. The Policy Section 6.1.5.4 recommends the RWQCB consider water body differences in land use, tributary inflow, or discharge input. The chemical and toxicity results from the ABLM and 08 Bight studies support the different water quality characteristics. The ABLM and 08 Bight studies also are consistent in that the reported failing toxicity results are all in the inner lagoon area. The outer and middle lagoon sections experience greater tidal flushing and the outer lagoon has significant sediment influx which requires periodic dredging events. In addition, if the AHL basins were treated as separate segments then the middle and outer lagoon would pass the toxicity evaluation criteria having no failing results reported. Cabrillo respectfully requests SD RWQCB consider the different attributes and uses of AHL as described above, consider the respective toxicity data summarized above, and remove the recommendation to place AHL on the 303(d) list. If the SD RWQCB determines that the recommendation stands, Cabrillo requests the SD RWQCB consider breaking up the AHL into separate segments and only recommend listing the AHL inner lagoon for toxicity in the final report. Cabrillo appreciates the opportunity to participate in the SD RWQCB's evaluation and 303(d) listing process. Should you have any questions regarding the enclosed you may contact Ms. Sheila Henika, RE. at (760) 268-4018 or sheila.henika@nrg.com. Regards, Cabrillo Power I LLC By: Its Authorized Agent, By: NRG Cabrillo Operations Inc. Jerry Carter Plant Manager cc: Ellan Lukey, City of Carlsbad Peter. MacLaggan, Poseidon Water Don Kent, Hubbs Seaworld Page 4 of 4 CABRILLO POWER I LLC, AGUA HEDIONDA LAGOON OUTER LAGOON FLOOD SHOAL MAINTENANCE DREDGING SEDIMENT SAMPLING AND ANALYSIS PLAN ACOE #2001100328-SKB Prepared for: Cabrillo Power I LLC 4600 Carlsbad Boulevard Carlsbad, CA 92009-4301 Prepared by: Merkel & Associates, Inc. 5434 Ruffin Road San Diego, CA 92123 Phone: (858) 560-5465 Fax: (858) 560-7779 October 2014 . October 2014 Merkel & Associates, Inc. #14-051-01 i TABLE OF CONTENTS 1.0 INTRODUCTION...........................................................................................................1 2.0 Background.....................................................................................................................1 3.0 Testing Program..............................................................................................................7 3.1 Core Logging and Sample Handling ...........................................................................9 3.2 Physical Analyses......................................................................................................11 4.0 REPORT PREPARATION...........................................................................................11 5.0 REFERENCES..............................................................................................................12 LIST OF FIGURES Figure 1. Proposed Beach and Lagoon Sampling Stations.......................................................8 LIST OF TABLES Table 1. Percent sand composition from prior shoal pre-dredging testing programs...............2 Table 2. Grain size and TOC results.........................................................................................2 Table 3. Sediment chemistry results.........................................................................................3 Table 4. Proposed sample locations at tidal basin and receiver location..................................9 . October 2014 Merkel & Associates, Inc. #14-051-01 1 CABRILLO POWER I LLC, AGUA HEDIONDA LAGOON OUTER LAGOON FLOOD SHOAL MAINTENANCE DREDGING SEDIMENT SAMPLING AND ANALYSIS PLAN ACOE #2001100328-SKB October 2014 1.0 INTRODUCTION This Sampling and Analysis Plan (SAP) is for the characterization of flood shoal sediment deposits within the outer basin of Agua Hedionda Lagoon. Maintenance shoal removal and beach replenishment are proposed to occur under ACOE IP #2001100328-SKB and are part of an on-going maintenance dredging program at the site. Dredging is completed every two to three years as required by shoal development. Under permit, up to 500,000 cubic yards of sediment may be dredged per maintenance interval. The dredging is all maintenance littoral sand removal with no cuts into native sediments. The material is to be cut by electric cutterhead dredge and replaced on coastal beaches on North Middle, and South Carlsbad State Beaches (sites are both up and down drift of the Agua Hedionda Lagoon tidal inlet). This SAP details the sediment collection and testing program to be conducted on the proposed dredged material in accordance with the standard procedures outlined in conditions of ACOE IP #2001100328-SKB, Evaluation of Dredged Material Proposed for Discharge in Waters of the U.S. (Inland Testing Manual [ITM]) (EPA/USACE 1998) and regional guidance of the USACE regulatory branch (USACE 1991). These guidance documents apply to inland waters, near-coastal waters, and surrounding environs. 2.0 BACKGROUND The outer basin (Outer Lagoon) of Agua Hedionda Lagoon is an efficient sediment trap for entrained littoral sand that is brought into the lagoon through the combined influence of tidal circulation and cooling water flows. Sediment accumulation in the flood shoal of the lagoon degrades the tidal prism and tidal flushing within the lagoon and also reduces the operational efficiency of the power plant located on the outer basin. Since initial lagoon dredging in 1954, the accumulated flood shoal sand has been dredged out every one to three years to maintain an open tidal connection with limited muting of the lagoon. Previous testing of the flood shoal has indicated that the shoal is comprised exclusively of beach sand (Table 1). During the most recent dredging sediment-testing program (2010), grain size analyses indicated the material was composed of 97.2 to 98.5 percent (%) sand (Table 1) and total organic carbon (TOC) values ranged from non-detectable (ND = 0.05 %) to 0.08%. Coincident with this, receiver beaches were found to have a sand content ranging from 95.1 to 99.5% across the various sampling years. Receiver beach TOC samples in 2010 were all below the 0.05% reporting limit (M&A 2010). . October 2014 Merkel & Associates, Inc. #14-051-01 2 Table 1. Percent sand composition from prior shoal pre-dredging testing programs. Year Percent Sand Source 1993 95.5%-97.5% MEC 1993 1995 96.0%-98.9% MEC 1995 1997 93.8%-98.0% MEC 1997 2000 98.4%-98.7% MEC 2000 2002 90.0%-97.1% MEC 2002 2004 97.4%-98.9% MEC-Weston 2004 2006 97.9%-98.7% Weston 2006 2008 97.7%-99.2% M&A 2008 2010 97.2%-98.5% M&A 2010 Most recently, in 2014 the California State Lands Commission requested a verification testing of the shoal sand chemistry in conjunction with issuance of a new long-term lease (Lease No. 932.1) allowing the placement of Agua Hedionda Lagoon maintenance dredged materials on to the beach. While the nature of the source material and physical characteristics of the sand are not conducive to be carriers of contaminants, testing was conducted for this verification purpose in July 2014. The same shoal area as has been recurrently dredged was tested using the same sampling stations distributed through the shoal (L-1 through L-3). In addition for beach compatibility, grain size and TOC was determined for the receiver beach (RB-1 through RB-3). Sediment grain size characteristics and TOC continued to reveal the littoral sand nature of the shoal (Table 2). Table 2. Grain size and TOC results. Sample Location Gravel (%) Sand (%) Silt (%) Clay (%) Mean Particle Size (mm) TOC (%) L-1 0.0 99.3 0.5 0.2 0.45 0.04% L-2 0.0 98.9 0.8 0.3 0.37 0.03% L-3 0.0 98.1 1.6 0.4 0.27 0.04% Average 0.0 98.8 1.0 0.3 0.36 0.04% RB-1 0.0 100.0 0.0 0.0 0.35 0.03% RB-2 0.0 98.9 0.8 0.3 0.38 0.02% RB-3 0.0 99.1 0.6 0.3 0.26 ND Average 0.0 99.4 0.4 0.1 0.33 -- ND = Not Detected There were very few chemicals of concern detected within the collected sediments; and when detected, concentrations were at low levels falling below established effects range median (ERM) and effects range low (ERL) guideline values, where such levels have been determined (Table 3). ERL and ERM values were developed as sediment quality guidelines to determine the potential for chemical contaminants in the sediment to cause adverse environmental effects (Buchman 2008; Long et al. 1995). The ERL is the lowest tenth percentile concentration of the available sediment toxicity data, and represents a concentration below which effects to sensitive species are not expected to occur. The ERM is the median effects concentration, above which adverse effects are likely to occur. . October 2014 Merkel & Associates, Inc. #14-051-01 3 Table 3. Sediment chemistry results. Compound Parameter Units ERL ERM L-1 L-2 L-3 Antimony mg/kg ND ND ND Arsenic mg/kg 8.2 70 0.785 0.673 1.06 Barium mg/kg 11.2 15.7 31.9 Beryllium mg/kg ND ND ND Cadmium mg/kg 1.2 9.6 ND ND ND Chromium mg/kg 81 370 2.42 3.39 6.51 Cobalt mg/kg 0.737 1.06 1.92 Copper mg/kg 34 270 1.17 1.7 3.05 Lead mg/kg 46.7 218 0.536 0.697 0.925 Mercury mg/kg 0.15 0.71 ND ND ND Molybdenum mg/kg ND ND ND Nickel mg/kg 20.9 51.6 0.992 1.45 2.33 Selenium mg/kg ND ND ND Silver mg/kg 1 3.7 ND ND ND Thallium mg/kg ND 0.037 0.087 Vanadium mg/kg 5.33 7.73 13.9 Metals Zinc mg/kg 150 410 8.82 13.5 20.0 Aldrin μg/kg ND ND ND Alpha-BHC μg/kg ND ND ND Beta-BHC μg/kg ND ND ND Delta-BHC μg/kg ND ND ND Gamma-BHC μg/kg ND ND ND Chlordane μg/kg ND ND ND Dieldrin μg/kg 0.02 8 ND ND ND Trans-nonachlor μg/kg ND ND ND 2,4'-DDD μg/kg ND ND ND 2,4'-DDE μg/kg ND ND ND 2,4'-DDT μg/kg ND ND ND 4,4'-DDD μg/kg 2 20 ND ND ND 4,4'-DDE μg/kg 2.2 27 ND ND ND 4,4'-DDT μg/kg 1 7 ND ND ND Total Detectable DDTs μg/kg 1.58 46.1 Endosulfan I μg/kg ND ND ND Endosulfan II μg/kg ND ND ND Endosulfan Sulfate μg/kg ND ND ND Endrin μg/kg ND ND ND Endrin Aldehyde μg/kg ND ND ND Chlorinated Pesticides Endrin Ketone μg/kg ND ND ND . October 2014 Merkel & Associates, Inc. #14-051-01 4 Table 3. Sediment chemistry results (continued). Compound Parameter Units ERL ERM L-1 L-2 L-3 Heptachlor μg/kg ND ND ND Heptachlor Epoxide μg/kg ND ND ND Methoxychlor μg/kg ND ND ND Toxaphene μg/kg ND ND ND Alpha Chlordane μg/kg ND ND ND Gamma Chlordane μg/kg ND ND ND Cis-nonachlor μg/kg ND ND ND Chlorinated Pesticides Oxychlordane μg/kg ND ND ND 1,6,7- Trimethylnaphthalene μg/kg ND ND ND 1-Methylnaphthalene μg/kg ND ND ND 1-Methylphenanthrene μg/kg ND ND ND 2-Methylnaphthalene μg/kg 70 670 ND ND ND 2,6- Dimethylnaphthalene μg/kg ND ND ND Acenaphthene μg/kg 16 500 ND ND ND Acenaphthylene μg/kg 44 640 ND ND ND Anthracene μg/kg 85.3 1100 ND ND ND Benzo (a) Anthracene μg/kg 261 1600 ND ND ND Benzo (a) Pyrene μg/kg 430 1600 ND ND ND Benzo (b) Fluoranthene μg/kg ND ND ND Benzo (e) Pyrene μg/kg ND ND ND Benzo (g,h,i) Perylene μg/kg ND ND ND Benzo (k) Fluoranthene μg/kg ND ND ND Benzoic Acid μg/kg ND ND ND Biphenyl μg/kg ND ND ND Chrysene μg/kg 384 2800 ND ND ND DCPA μg/kg ND ND ND Dibenz (a,h) Anthracene μg/kg 63.4 260 ND ND ND Dibenzothiophene μg/kg ND ND ND Fluoranthene μg/kg 600 5100 ND ND ND Fluorene μg/kg 19 540 ND ND ND Indeno (1,2,3-c,d) Pyrene μg/kg ND ND ND Isophorone μg/kg ND ND ND Naphthalene μg/kg 160 2100 ND ND ND Perthane μg/kg ND ND ND Perylene μg/kg ND ND ND PAHs Phenanthrene μg/kg 240 1500 ND ND ND . October 2014 Merkel & Associates, Inc. #14-051-01 5 Table 3. Sediment chemistry results (continued). Compound Parameter Units ERL ERM L-1 L-2 L-3 Pyrene μg/kg 665 2600 ND ND ND PAHs Total PAHs μg/kg 4022 44792 2,3,4,6- Tetrachlorophenol μg/kg ND ND ND 2,4,5-Trichlorophenol μg/kg ND ND ND 2,4,6-Trichlorophenol μg/kg ND ND ND 2,4-Dichlorophenol μg/kg ND ND ND 2,4-Dimethylphenol μg/kg ND ND ND 2,4-Dinitrophenol μg/kg ND ND ND 2,6-Dichlorophenol μg/kg ND ND ND 2-Chlorophenol μg/kg ND ND ND 2-Methylphenol μg/kg ND ND ND 2-Nitrophenol μg/kg ND ND ND 3/4-Methylphenol μg/kg ND ND ND 4,6-Dinitro-2- Methylphenol μg/kg ND ND ND 4-Chloro-3- Methylphenol μg/kg ND ND ND 4-Nitrophenol μg/kg ND ND ND Pentachlorophenol μg/kg ND ND ND Phenols Phenol μg/kg ND ND ND Bis(2-Ethylhexyl) Phthalate μg/kg 13 11 14 Butyl Benzyl Phthalate μg/kg 6.6 6.1 18 Diethyl Phthalate μg/kg ND ND ND Dimethyl Phthalate μg/kg 240 370 400 Di-n-Butyl Phthalate μg/kg ND ND ND Phtalates Di-n-Octyl Phthalate μg/kg ND ND ND PCB003 μg/kg ND ND ND PCB008 μg/kg ND ND ND PCB018 μg/kg ND ND ND PCB028 μg/kg ND ND ND PCB031 μg/kg ND ND ND PCB033 μg/kg ND ND ND PCB037 μg/kg ND ND ND PCB044 μg/kg ND ND ND PCB049 μg/kg ND ND ND PCB052 μg/kg ND ND ND PCB056 μg/kg ND ND ND PCBs PCB060 μg/kg ND ND ND . October 2014 Merkel & Associates, Inc. #14-051-01 6 Table 3. Sediment chemistry results (continued). Compound Parameter Units ERL ERM L-1 L-2 L-3 PCB066 μg/kg ND ND ND PCB070 μg/kg ND ND ND PCB074 μg/kg ND ND ND PCB077 μg/kg ND ND ND PCB081 μg/kg ND ND ND PCB087 μg/kg ND ND ND PCB095 μg/kg ND ND ND PCB097 μg/kg ND ND ND PCB099 μg/kg ND ND ND PCB101 μg/kg ND ND ND PCB105 μg/kg ND ND ND PCB110 μg/kg ND ND ND PCB114 μg/kg ND ND ND PCB118 μg/kg ND ND ND PCB119 μg/kg ND ND ND PCB123 μg/kg ND ND ND PCB126 μg/kg ND ND ND PCB128 μg/kg ND ND ND PCB132 μg/kg ND ND ND PCB138/158 μg/kg ND ND ND PCB141 μg/kg ND ND ND PCB149 μg/kg ND ND ND PCB151 μg/kg ND ND ND PCB153 μg/kg ND ND ND PCB156 μg/kg ND ND ND PCB157 μg/kg ND ND ND PCB167 μg/kg ND ND ND PCB168 μg/kg ND ND ND PCB169 μg/kg ND ND ND PCB170 μg/kg ND ND ND PCB174 μg/kg ND ND ND PCB177 μg/kg ND ND ND PCB180 μg/kg ND ND ND PCB183 μg/kg ND ND ND PCB184 μg/kg ND ND ND PCB187 μg/kg ND ND ND PCB189 μg/kg ND ND ND PCBs PCB194 μg/kg ND ND ND . October 2014 Merkel & Associates, Inc. #14-051-01 7 Table 3. Sediment chemistry results (continued). Compound Parameter Units ERL ERM L-1 L-2 L-3 PCB195 μg/kg ND ND ND PCB200 μg/kg ND ND ND PCB201 μg/kg ND ND ND PCB203 μg/kg ND ND ND PCB206 μg/kg ND ND ND PCB209 μg/kg ND ND ND PCBs Total PCB Congeners μg/kg 22.7 180 Notes: All results reported as dry weight. Bold Text – Exceeds ERL Bold and Underlined Text – Exceeds ERM ND = not detected above the reporting limit. Some analytes are reported that were detected at a concentration below the reporting limit and above the laboratory method detection limit. See Eurofins report in Appendix C for all estimated values. mg/kg - milligram per kilogram, μg/kg - micrograms per kilogram, ERL - Effects Range Low, ERM - Effects Range Median, DDT – dichlorodiphenyltrichloroethane, PAH - polycyclic aromatic hydrocarbons, PCB - polychlorinated biphenyls As would be expected, the conditions of the lagoon remain substantively unchanged from those existing during the 2010 sediment-testing program and the chemical testing performed provided a refreshed verification that the sand in the shoal is clean sediment. In addition, M&A has worked extensively within Agua Hedionda Lagoon in association with the recent eradication of the invasive alga, Caulerpa taxifolia from the system and subsequent eelgrass surveys. As a result, M&A staff members have first hand information regarding lagoon conditions and believe there is no reason to suspect any change in sediment conditions from those occurring in prior sampling events. 3.0 TESTING PROGRAM Sediment testing is proposed in accordance with the requirements of regulatory permits and the “Evaluation of Dredge Material Proposed for Discharge in Waters of the U.S. – Testing Manual” (Inland Testing Manual) (Environmental Protection Agency (EPA)/U.S. Army Corps of Engineers (USACE) 1998). Merkel & Associates, Inc. (M&A), under contract to Cabrillo Power I LLC, will manage the sediment collection and testing study. This study will include the following elements: • Preparation of this SAP; • Collection of sediment core samples to project depth according to the procedures outlined in the SAP; • Physical analyses on test sediment composites for the flood shoal to be dredged and receiver beach, and; • Data analysis and report preparation. Sampling locations for the maintenance dredging of the outer lagoon and the receiver beaches follow the distribution of effort for prior testing events (Figure 1). Beach and Lagoon Sampling Stations Figure 1 M&A #14-051-02 !( !( !( #* #* #* L3 L2 L1 RB3 RB2 RB1 Merkel & Associates, Inc.µ 0 500 1,000 1,500250Feet !(Lagoon Station #*Beach Receiving Station AGUA HEDIONDALAGOON . October 2014 Merkel & Associates, Inc. #14-051-01 9 Samples are to be collected by continuous core through the accumulated sands. Samples will be taken to the proposed dredge depth plus 2-feet of over dredge to a depth of –19 ft MLLW. The target core depth will be –19 ft to –20 ft from a top elevation of the flood shoal at 0 to +1 foot MLLW. Cores will be taken to the target depth or depth of refusal. Lagoon core sample distribution (L1-L3) has been determined such that each continuous core represents approximately one third of the dredge material volume to be removed. Coordinates and target penetration is shown for each proposed sampling site in Table 2. Actual sampled locations shall be recorded to a ±3 meter accuracy using GPS. Receiver beaches are to be sampled at high (+5 to +7 feet MLLW) and low (-2 to +1 feet MLLW) intertidal elevations. Samples shall consist of surface sands collected by using a 6- inch deep hand core. Beach samples shall be collected from Carlsbad State Beach at the north (RB1), middle (RB2), and south (RB3) beaches where material is to be placed. Proposed sampling coordinates for beach sites are provided in Table 4. Table 4. Proposed sample locations at tidal basin and receiver location. Site Approx. Volume (yd3) Sample Location Longitude Latitude Target Penetration (ft) L-1 117o 20’33” 33o 08’45” 19 L-2 117o 20’29” 33o 08’41” 19 Shoal (Outer Lagoon ) 350,000 L-3 117o 20’24” 33o 08’38” 19 RB-1 117o 20’55” 33o 08’59” 0.5 RB-2 117o 20’29” 33o 08’30” 0.5 Receiver Site (Beach) RB-3 117o 20’19” 33o 08’13” 0.5 There is no reason to suspect contamination or deviation from prior sediment sampling conditions. Sediments in the maintenance dredging area have accumulated over a very short time period and from high-energy littoral sand sources. It is anticipated that grain size of the lagoon sediments to be dredged will far exceed 90% sand fraction and will hold very low TOC as they have done for all prior maintenance cycles. Sediments of this character typically do not retain contaminants and thus there is no reason to suspect contamination of the maintenance dredging area. Based on this condition it is suggested that proposed dredging of these sediments for beach replenishment purposes meets the ITM Tier 1 exclusion criteria and therefore do not warrant testing or analysis beyond beach compatibility assessments. For this reason, it is proposed that testing be completed to confirm grain size distribution and TOC. 3.1 CORE LOGGING AND SAMPLE HANDLING Core samples will be carefully extruded onto clean, plastic trays, photographed, and observed for unique strata, color, odors, etc. These observations, along with information on weather, currents, tides, winds, and other site conditions, will be recorded in the field log. . October 2014 Merkel & Associates, Inc. #14-051-01 10 The following information will be recorded during the sediment collection program in a project-specific field log: • Date and time of collection • Sample identification code • Sampling location (latitude/longitude to within a 3-meter accuracy) • Water depth or elevation (± 0.1 ft) • Tidal stage and currents • Climatic conditions • Sampling method and any problems encountered • Core penetration/core recovery • Description of the material type obtained in the samples (color, odor, etc.) • Description of any vertical stratification in each core • Description of sediment subsampling methods if any required Sediment stratification has not been observed in any of the prior characterizations of the flood shoal and as such no stratification is anticipated in the present effort. As a result, a composite sample will be collected from the entire core length. If distinct stratification greater than 2 feet is detected, then a separate sample will be taken from the strata although will not be analyzed until results from the composite sample are available and appears warranted. Each core sample will be thoroughly homogenized in clean, non-contaminating stainless steel mixing vessels and subsampled for archive purposes. Collected sediments shall be kept separate in individual sample containers labeled with individual sample identification, date and time of collection and samples will be stored with ice packs at approximately 4ºC until analyzed by the laboratory. Archived samples will be put into labeled 16 oz (500 ml) glass jars with teflon-lined lids and frozen. Samples will be held for a period of three months following submittal of the testing report. At which point they will be disposed of unless the client requests transfer of the sample. The integrity of each sample from the time of collection to the point of data reporting must be maintained throughout the study. Proper record keeping and chain-of-custody procedures will be implemented to allow samples to be traced from collection to their final disposition. After collection of sediment, documentation on various logs and forms will be required to adequately identify and catalog station and sample information. Field log entries will be completed at the time that observations are made. Sample container identification information will be recorded on the chain-of-custody form. The chain-of-custody forms will also identify the sampling organization, point of contact, sample collection date and time, type of sample, and project. The form will also serve as a sample analysis request form. Samples will be sent to the laboratory along with a chain-of- custody form specifying the sample identification and the analyses to be conducted (by referencing a list of specific analyses or the statement of work for the laboratory). These forms will be prepared in triplicate; the field supervisor will retain one copy, and the other 2 copies will accompany the shipment. Proper completion of all chain-of-custody documentation will be the responsibility of the field manager. Chain-of-custody forms will be completed and signed before the end of each . October 2014 Merkel & Associates, Inc. #14-051-01 11 sampling day and before the samples are removed from the vessel or pass from the control of the field supervisor. Chain-of-custody forms will be signed at each additional point of transfer of samples between the field and the laboratory as well as within the laboratory. Receiver beach sediments are to be collected and processed similarly to the dredge site sediments for compatibility assessment. High and low beach samples at each site are to be composited to create a characterization of the individual site. All samples will be processed as bulk samples with no subsampling or stratified sampling. 3.2 PHYSICAL ANALYSES The analyses for the proposed study are as follows: • Grain size analyses will be performed on the test composite and receiver site samples following the EPA/USACE-approved method (ASTM 1967). Percent sand, silt, and clay will be reported to 0.1 percent, along with the corresponding millimeter and phi sizes and a cumulative grain size distribution diagram. • Total Organic Carbon (TOC) will be determined in accordance with ASTM D2579. TOC will be tabulated as percent carbon by sample weight. All six samples (L1-L3 and RB1-RB-3) will be analyzed for TOC and grain size distribution. Tabular data shall be presented as individual samples and mean of the results for the lagoon dredging area and the receiver beach areas. Grain size distribution data for the dredge and receiver areas will be used to evaluate sediment compatibility. 4.0 REPORT PREPARATION The draft and final study reports will contain the following information: • Introduction – Includes a project description and a history of the site, historical uses, results of previous toxicity or sediment work, known contamination or discharges, and other relevant information • Site Maps – Shows the test sediment collection locations • Core Log – Includes core collection coordinates, target/actual penetration, and sediment characteristics (e.g., strata, color, odor) • Methods and Materials – Includes all information pertaining to test sediment collection, handling, and analyses • Results – Includes results from any physical and chemical testing • Discussion – Includes a detailed description of any chemical and physical characteristics of the test sediments • References • Photographic Documentation • Quality Assurance/Quality Control Information . October 2014 Merkel & Associates, Inc. #14-051-01 12 5.0 REFERENCES American Society for Testing and Materials (ASTM). 1967. Standard Methods for Grain- Size Analysis of Soils. ASTM Designation D422- 63, Part II. Buchman, M.F. 2008. NOAA Screening Quick Reference Tables, NOAA OR&R Report 08-1, Seattle WA, Office of Response and Restoration Division, National Oceanic and Atmospheric Administration, 34 pages. Environmental Protection Agency (EPA)/U.S. Army Corps of Engineers (USACE). 1998. Evaluation of Dredged Material Proposed for Discharge in Waters of the U.S., Testing Manual: Inland Testing Manual. EPA Reference 823-B-98-004. February. Long, E.R., D.L. MacDonald, S.L. Smith, and F.D. Calder. 1995. Incidence of Adverse Biological Effects within Ranges of Chemical Concentration in Marine and Estuarine Sediments. Environmental Management 19 (1): 81-97. MEC-Weston, Inc. 2004. Cabrillo Power 1 LLC Agua Hedionda Lagoon Field Investigations for Outer Lagoon Dredging, Data Report November 2004. MEC. 2002. Agua Hedionda Lagoon, Field investigations for outer lagoon dredging. Submitted to Cabrillo Power, October 2002. MEC. 2002. Cabrillo Power 1 LLC Agua Hedionda Lagoon 2002 Outer Lagoon/Beach Sediment Sampling and Analysis Plan. MEC. 2000. Agua Hedionda Lagoon, Field investigations for outer lagoon dredging. Submitted to Cabrillo Power, September 2000. MEC. 1997a. Agua Hedionda Lagoon, Field investigations for middle lagoon dredging. Submitted to SDG&E, April 1997. MEC. 1997b. Environmental Conditions and Potential Impacts Associated With Dredging the Inner Section of Agua Hedionda Lagoon. Submitted to SDG&E, May 1997. MEC. 1995. SDG&E Encina Power Plant, Agua Hedionda Lagoon dredge sediment analysis. Submitted to SDG&E, June 1995. MEC. 1993. Field investigations for lagoon dredging. Submitted to SDG&E, November 1993. Merkel & Associates, Inc. (M&A). 2010. Cabrillo Power I LLC, Agua Hedionda Lagoon Outer Lagoon Flood Shoal Maintenance Dredging Sediment Characterization Report. December 2010. Merkel & Associates, Inc. (M&A). 2008. Cabrillo Power I LLC, Agua Hedionda Lagoon Outer Lagoon Flood Shoal Maintenance Dredging Sediment Characterization Report. December 2008. Pam Drew From: Smith, Robert R Jr CIV CESPL CESPD (US) <Robert.R.Smith@usace.army.mil > Sent: Tuesday, September 12, 2017 6:44 AM To: Pam Drew; Monji, Alan@Waterboards; Ota, Allan; Henika, Sheila Cc: James Wood; Tim Murphy; Jeremy Riddle; Jason Geldert Subject: RE: Agua Hedionda Lagoon Dredging Permits Pam, The Corps in coordination with EPA makes testing determinations in accordance with procedures per the Inland Testing Manual and a Corps Regulatory Guidance Letter 06-02 for any proposed activity where dredged material is to be discharged into waters of the U.S. If ocean disposal is involved at an approved ocean disposal site (LA-5) then the Ocean Testing Manual is involved. It is quite complex and depends on lots of factors. Call me if you need more specific information. Original Message From: Pam Drew [mailto:Pam.Drew@carlsbadca.gov] Sent: Monday, September 11, 2017 5:33 PM To: Monji, Alan@Waterboards <Alan.Monji@waterboards.ca.gov>; Smith, Robert R Jr CIV CESPL CESPD (US) <Robert.R.Smith@usace.army.mil> Cc: James Wood <James.Wood@carlsbadca.gov>; Tim Murphy <Tim.Murphy@carlsbadca.gov>; Jeremy Riddle <Jerenny.Riddle@carlsbadca.gov>; Jason Geldert <Jason.Geldert@carlsbadca.gov> Subject: [EXTERNAL] RE: Agua Hedionda Lagoon Dredging Permits Thank you Alan for the quick and thorough response. Just to clarify it would be your agencies responsibility to require, or not require, testing not the Army Corps? Or, does the Army Corps also have the ability to require testing? This was one of the questions we need answered. Thank you so much, From: Monji, Alan@Waterboards [mailto:Alan.Monji@waterboards.ca.gov] Sent: Monday, September 11, 2017 5:06 PM To: Pam Drew <Pam.Drew@carlsbadca.gov>; Robert.r.smith@usace.army.mil Cc: James Wood <James.Wood@carlsbadca.gov>; Tim Murphy <Tim.Murphy@carlsbadca.gov>; Jeremy Riddle <Jeremy.Riddle@carlsbadca.gov>; Jason Geldert <Jason.Geldert@carlsbadca.gov> Subject: RE: Agua Hedionda Lagoon Dredging Permits Hi Pam: Yes we are aware of Mary Anne's concerns. She has been in contact with Helen Yu from my office concerning the 303d listing and sent us emails last week expressing her concerns for the lagoon. From the data I saw, the toxicity listing was ATTACHMENT 5 for the area east of the 5 based on samples collected in 2003, 2004, 2005, and 2008. Data SCCWRP collected in 2013 show little or no sediment toxicity in the eastern lagoon. Sediment chemistry data from 2014 dredging of the lagoon near the power plant show mostly non detect contaminants or levels below ERLs. See attached emails. We have a meeting schedule with NRG to discuss the dredging project next week. We haven't really discussed her request for additional sediment toxicity testing but the sediment chemistry results from 2014 don't seem to support the need for toxicity testing unless there have been significant changes/spills/unauthorized discharges to the lagoon since 2014. Aran <Blockedhttps://www.facebook.com/San-Diego-Regional-Water-Quality-Control-Board-141716669201479/> <Blockedhttps://twitter.com/SDWaterBoard?lang=en> ><((((-9->s-. From: Pam Drew [mailto:Pam.Drew@carlsbadca.gov] Sent: Monday, September 11, 2017 4:18 PM To: Robert.r.snnith@usace.army.mil <mailto:Robert.r.smith@usace.army.mil>; Monji, Alan@Waterboards <Alan.Monji@waterboards.ca.gov <mailto:Alan.Monji@waterboards.ca.gov> > Cc: James Wood <James.Wood@carlsbadca.gov <mailto:James.Wood@carlsbadca.gov> >; Tim Murphy <Tim.Murphy@carlsbadca.gov <mailto:Tim.Murphy@carlsbadca.gov> >; Jeremy Riddle <Jeremy.Riddle@carlsbadca.gov <mailto:Jeremy.Riddle@carlsbadca.gov> >; Jason Geldert <Jason.Geldert@carlsbadca.gov <mailto:Jason.Geldert@carlsbadca.gov> > Subject: Agua Hedionda Lagoon Dredging Permits Hi Robert and Alan, You may already be aware of this, but NRG went before the city's Planning Commission last week for approval of a floodplain Special Use Permit to dredge the outer lagoon beginning in January of 2018. A resident, Mary Anne Viney, spoke during the item and said that the Lagoon has tested positive in the past for toxins and that the Lagoon may get on the 303d list the Board keeps. The Planning Commissioners were very hesitant to approve the permit without guarantees that other resource agencies would require the soil to be tested for contaminants prior to the sand being put on the beach. What information can you give me about testing of the water in the lagoon, the 303d listing, and conditions your agency includes on permits for dredging the lagoon? Also, which agencies purview is it to require the soil to be tested? If you are not the person to answer these questions, please forward this email to the right person. I hope I can get your responses soon as I have to prepare a staff report for the next PC meeting, which is scheduled for September 20. 2 Pam Drew From: Yu, Helen@Waterboards <Helen.Yu@waterboards.ca.gov> Sent: Friday, September 08, 2017 9:23 AM To: Becker, Eric@Waterboards; Gorham, Cynthia@Waterboards; Monji, Alan@Waterboards; Neill, Ben@Waterboards Subject: FW: Toxicity samples evaluated in 2014 IR Attachments: 899_1313SedToxReport.pdf Sorry for sending this again. I just noticed a typo in my previous email, I meant based on the sediment data we have, there hasn't been any toxicity detected from outer lagoon... Xueyuan (Helen) Yu San Diego Regional Water Quality Control Board (619)521-5893 From: Yu, Helen@Waterboards Sent: Friday, September 08, 2017 9:12 AM to: Becker, Eric@Waterboards <eric.becker@waterboards.ca.gov>; Gorham, Cynthia@Waterboards <cynthia.gorham@waterboards.ca.gov>; Neill, Ben@Waterboards <ben.neill@waterboards.ca.gov>; Monji, Alan@Waterboards <alan.monji@waterboards.ca.gov> Subject: RE: Toxicity samples evaluated in 2014 IR I think it's safe to say based on the sediment data we have, there hasn't been any samples in the outer lagoon showing toxicity. Attached is the Bight 13 report for sediment toxicity, as shown in the two interactive maps of Appendix C and D, there hasn't been any toxicity in sediment in the outer lagoon. However, I vaguely remember that Ben once forwarded an email about detecting toxicity in in-take waters by the Power Plant/desalt plant. I don't know the follow up of that email. I've included Ben in this email to shed some light on this... Xueyuan (Helen) Yu San Diego Regional Water Quality Control Board (619)521-5893 From: Becker, Eric@Waterboards Sent: Friday, September 08, 2017 8:57 AM To: Yu, Helen@Waterboards <Helen.Yu@waterboards.ca.gov>; Gorham, Cynthia@Waterboards <Cynthia.Gorham@waterboards.ca.gov>; Monji, Alan@Waterboards <Alan.Monii@waterboards.ca.gov> Subject: RE: Toxicity samples evaluated in 2014 IR So can we tell the reporter that we have no samples showing toxicity in the outer lagoon? From: Yu, Helen@Waterboards Sent: Thursday, September 07, 2017 7:29 PM To: Gorham, Cynthia@Waterboards <Cynthia.Gorham@waterboards.ca.gov>; Monji, Alan@Waterboards <Alan.Monii@waterboards.ca.gov> 1 Cc: Becker, Eric@Waterboards <Eric.Becker@waterboards.ca.gov> Subject: Re: Toxicity samples evaluated in 2014 IR All three were composite samples from the east lagoon. None from the outer (western) lagoon. Helen From: Gorham, Cynthia@Waterboards Sent: Thursday, September 7, 2017 4:06:20 PM To: Monji, Alan@Waterboards; Yu, Helen@Waterboards Cc: Becker, Eric@Waterboards Subject: RE: Toxicity samples evaluated in 2014 IR Where are they located? From: Monji, Alan@Waterboards Sent: Thursday, September 07, 2017 3:58 PM To: Gorham, Cynthia@Waterboards <Cynthia.Gorham@waterboards.ca.gov>; Yu, Helen@Waterboards <Helen.Yu@waterboards.ca.gov> Cc: Becker, Eric@Waterboards <Eric.Becker@waterboards.ca.gov> Subject: RE: Toxicity samples evaluated in 2014 IR 904AHL_2003 904AHL_2004 904AHL_2005 Alan Like Us On f facebook ><((((°>'.. ><((((2> ><((((2>s.• ><((((2> From: Gorham, Cynthia@Waterboards Sent: Thursday, September 07, 2017 3:57 PM To: Monji, Alan@Waterboards <Alan.Monji@waterboards.ca.gov>; Yu, Helen@Waterboards <Helen.Yu@waterboards.ca.gov> Cc: Becker, Eric@Waterboards <Eric.Becker@waterboards.ca.gov> Subject: RE: Toxicity samples evaluated in 2014 IR Where is the ABLM sampling station? All three samples are toxic here. From: Monji, Alan@Waterboards Sent: Thursday, September 07, 2017 3:05 PM To: Gorham, Cynthia@Waterboards <Cvnthia.Gorham@waterboards.ca.gov>; Becker, Eric@Waterboards <Eric.Becker@waterboards.ca.gov> Subject: FW: Toxicity samples evaluated in 2014 IR Amphipod testing data from Helen for Agua Hedionda Lagoon. Alan cs us On facebtx) ><((((°>'-• S. ><((((2> ><((((9>'.. s• ><((((°> From: Yu, Helen@Waterboards Sent: Thursday, September 07, 2017 2:44 PM To: Monji, Alan@Waterboards <Alan.Monii@waterboards.ca.gov> Subject: Toxicity samples evaluated in 2014 IR Hi Alan, The failed toxicity test of sediment from Agua Hedionda Lagoon in Bight 08 is about Eohaustorius estuaries. (Station Number 6271) . Composite samples from county's ABLM program also show toxicity on this species. The location of samples are in the attached figure. Let me know if you have other questions. Thanks, Xueyuan (Helen) Yu San Diego Regional Water Quality Control Board (619)521-5893 3 Pam Drew From: Smith, Robert R Jr CIV CESPL CESPD (US) <Robert.R.Smith@usace.army.mil> Sent: Thursday, September 07, 2017 3:04 PM To: Monji, Alan@Waterboards Cc: Ota, Allan Subject: FW: [EXTERNAL] Sediment Toxicity Testing Condition for Agua Hedionda Lagoon 2018 Dredging Event: City of Carlsbad Special Use Permit (UNCLASSIFIED) Attachments: 14-051-01 Agua Hedionda Sediment Report_Final.pdf; 14-051-02_2014 Sediment SAP_ACOE.pdf; 2014 Sediment SAP_CSLC_Final.pdf CLASSIFICATION: UNCLASSIFIED Alan, Here are the Aqua Hedionda lagoon SAPs. Call me next week if you want to discuss. Original Message From: Henika, Sheila [nnailto:Sheila.Henika@nrg.com] Sent: Thursday, September 7, 2017 2:59 PM To: Smith, Robert R Jr CIV CESPL CESPD (US) <Robert.R.Smith@usace.army.mil> Cc: Ota, Allan <Ota.Allan@epa.gov>; Piantka, George <George.Piantka@nrg.com>; Sisk, Tim <Tim.Sisk@nrg.com> Subject: RE: [EXTERNAL] Sediment Toxicity Testing Condition for Agua Hedionda Lagoon 2018 Dredging Event: City of Carlsbad Special Use Permit (UNCLASSIFIED) Army Corps (yourself), City of Carlsbad, RWQCB, California Department of Fish and Wildlife, and California Coastal Commission have all been approached by either Ms. Viney or Ms. Wright about their concerns. SAP and Analytical Reports attached. I had intended to repeat the same analysis for this dredge cycle. Please let me know when you are available to discuss next week. Sheila Henika, P.E., MBA-TM Environmental Supervisor NRG Energy, West Development Permitting & Compliance 5790 Fleet Street, Suite 200 Carlsbad, CA 92008 (760) 268-4018 (o) (760) 535-2705 (c) sheila.henika@nrg.com Note: The information contained in this e-mail and any accompanying documents may contain information that is confidential or otherwise protected from disclosure. If you are not the intended recipient of this message, or if this message has been addressed to you in error, please immediately alert the sender by reply e-mail and then delete this message, including any attachments. Any dissemination, distribution or other use of the contents of this message by anyone other than the intended recipient is strictly prohibited. 1 Original Message From: Smith, Robert R Jr CIV CESPL CESPD (US) [mailto:Robert.R.Smith@usace.army.mil] Sent: Thursday, September 07, 2017 2:52 PM To: Henika, Sheila Cc: Ota, Allan Subject: RE: [EXTERNAL] Sediment Toxicity Testing Condition for Agua Hedionda Lagoon 2018 Dredging Event: City of Carlsbad Special Use Permit (UNCLASSIFIED) CLASSIFICATION: UNCLASSIFIED FYI do you have the SAP report that EPA and myself looked at back in October 2014? Can you resend it? I lost it in my hard drive crash but I believe its in our hard copy file. Are we to do both grain size and bulk chemistry testing (at last Tier II) in the next SAP ( I think we should at least do Tier II)? Both Regional Board and myself are getting inquiries as to the next round of testing. Please confirm. Thanks. Original Message From: Henika, Sheila [mailto:Sheila.Henika@nrg.conn] Sent: Thursday, September 7, 2017 2:39 PM To: Smith, Robert R Jr CIV CESPL CESPD (US) <Robert.R.Smith@usace.army.mil> Cc: Ota, Allan <Ota.Allan@epa.gov>; Piantka, George <George.Piantka@nrg.com>; Sisk, Tim <Tim.Sisk@nrg.com> Subject: RE: [EXTERNAL] Sediment Toxicity Testing Condition for Agua Hedionda Lagoon 2018 Dredging Event: City of Carlsbad Special Use Permit (UNCLASSIFIED) Robert, Yes, we should discuss. Yes, we will be doing a SAP and subsequent analysis. By the way, the 2012 303(d) list is the most current list with the State Water Resources Control Board. Agua Hedionda Lagoon is NOT listed on the 2012 303(d) list for any pollutant. The sediment toxicity issues Ms. Viney is discusses are only proposals under the pending updated list and therefore not currently subject to regulation by the SWRCB. Thank you for forwarding her note. BlockedBlockedhttp://www.waterboards.ca.gov/water_issues/progranns/water_quality_assessmentMimpaired Regards, Sheila Sheila Henika, P.E., MBA-TM Environmental Supervisor NRG Energy, West Development Permitting & Compliance 5790 Fleet Street, Suite 200 Carlsbad, CA 92008 (760) 268-4018 (o) (760) 535-2705 (c) sheila.henika@nrg.com Note: The information contained in this e-mail and any accompanying documents may contain information that is confidential or otherwise protected from disclosure. If you are not the intended recipient of this message, or if this message has been addressed to you in error, please immediately alert the sender by reply e-mail and then delete this 2 message, including any attachments. Any dissemination, distribution or other use of the contents of this message by anyone other than the intended recipient is strictly prohibited. Original Message From: Smith, Robert R Jr CIV CESPL CESPD (US) [mailto:Robert.R.Smith@usace.army.mil] Sent: Thursday, September 07, 2017 2:29 PM To: Henika, Sheila Cc: Ota, Allan Subject: FW: [EXTERNAL] Sediment Toxicity Testing Condition for Agua Hedionda Lagoon 2018 Dredging Event: City of Carlsbad Special Use Permit (UNCLASSIFIED) CLASSIFICATION: UNCLASSIFIED Sheila, FYI Sheila here is an email from Mary Anne Viney, and next week if you want we can discuss with me. Based on our last telcon this lady sent this response below. I am assuming per our telcon yesterday we are doing a full SAP for the next dredging cycle (grain size and bulk chemistry) but if otherwise we can discuss. I am out tomorrow but we can discuss next week. The EPA POC Allan Ota may be this month. Thanks for keeping a good track record of the emails. Original Message From: maryanneviney@dslextreme.conn [nnailto:maryanneviney@dslextreme.com] Sent: Thursday, September 7, 2017 11:52 AM To: Smith, Robert R Jr CIV CESPL CESPD (US) <Robert.R.Smith@usace.army.mil> Cc: Alan.Monji@waterboards.ca.gov Subject: [EXTERNAL] Sediment Toxicity Testing Condition for Agua Hedionda Lagoon 2018 Dredging Event: City of Carlsbad Special Use Permit Hi Robert, It was nice to speak with you this morning. This is a follow-up email to our phone call conversation this morning, and I would like to meet at your earliest convenience regarding the following: The City of Carlsbad Planning Commission met last night to approve a special use permit for January 2018 dredging of the Aqua Hedionda Lagoon. Because the Aqua Hedionda Lagoon is 303(d) listed as impaired for sediment toxicity, I requested that the permit be conditioned for NRG to test for sediment toxicity before the dredged materials are disposed of on the public Carlsbad beaches. The Planning Commission then decided to postpone the vote for the permit until Wednesday, September 20, 2017. I respectfully request the AOE's support for this condition and appreciate any assistance in this matter. Please let me know if there is any other information concerning this matter I can provide. Thank you. 3 With kind regards Mary Anne Viney 760-710-1425 CLASSIFICATION: UNCLASSIFIED CLASSIFICATION: UNCLASSIFIED CLASSIFICATION: UNCLASSIFIED 4