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Home My WebLink About2020-10-06; Beach Preservation Commission; ; 1020-4 REPORT ON MAINTENANCE DREDGING PROJECT FOR AGUA HEDIONDA LAGOON Meeting Date: Oct. 6, 2020 To: Beach Preservation Commission From: Kyle Lancaster, Parks & Recreation Director Staff Contact: Michael Tully, Parks Planner Subject: Maintenance Dredging Project for Agua Hedionda Lagoon Recommended Action Receive a report on the upcoming maintenance dredging project for Agua Hedionda Lagoon, to be conducted by Poseidon Resources – the desalination plant operator. Discussion Background Since 1954, maintenance dredging projects have been conducted at intervals of one to four years to remove a flood-tide shoal that forms in the Agua Hedionda Lagoon outer basin, to maintain tidal exchange throughout the lagoon and provide cooling water flowrates required for Cabrillo Power operations. Cabrillo Power discontinued operations requiring the cooling water in December 2018. However, maintenance dredging of the outer basin continues to be necessary to maintain tidal exchange throughout the lagoon, and to provide seawater to support the operation of the Claude “Bud” Lewis Carlsbad Desalination Plant. The most recent maintenance dredging project was completed in the spring of 2018 and deposited 205,482 cubic yards of sand back onto Carlsbad beaches. Overview Cabrillo Power I LLC and Poseidon Resources LP plan to conduct a maintenance dredging and beach nourishment project in 2020/21 to remove a flood-tide shoal in the outer basin (also referred to as the west basin) of Agua Hedionda Lagoon in order to maintain tidal exchange between the lagoon and ocean. Similar operations have been performed over the last six decades. Range from 159,000 to 429,000 cubic yards (cy) of sand may typically be removed from the lagoon – outer basin. The most recent operation, completed in 2018, accounted for 205,482 cy. In keeping with past projects, the dredged sand will be placed on adjacent beaches: north beach (from the lagoon’s inlet jetty to approximately Pine Avenue), middle beach (between the lagoon’s inlet and outlet jetties), and south beach (from the outlet jetty to approximately the Terramar residential development). The dredging project operations will be conducted between October 2020 and April 2021. Sand placement quantities for each receiver beach is determined based on the conditions reflected in a beach profile survey conducted within 45 days of the commencement of the dredging project. Currently it is anticipated to place approximately 200,000 cy on the north beach, 42,000 cy on the middle beach, and 58,000 cy on the south beach. All dredging work is anticipated to be completed by April 15, 2021. The city is one of several regulatory agencies, including the San Diego Regional Water Quality Control Board, the California Coastal Commission, the California State Lands Commission, the California Department of Parks & Recreation, and the U.S. Army Corps of Engineers, to review plans and issue permits to Cabrillo Power I LLC and Poseidon Resources LP for the dredging work. On Aug. 5, 2020, Community Development staff distributed first review comments to Poseidon Resources LP on the Special Use Permit application for the Agua Hedionda Lagoon - Outer Basin 2020-21 Maintenance Dredge and Beach Nourishment Cycle Sand Disposition Plan. Once the review comments are addressed and the application is returned, staff will resume its standard activities in processing such permits. Cabrillo Power I LLC and Poseidon Resources LP will be responsible for funding, monitoring and inspecting the maintenance dredging project. Public Outreach Poseidon Resources LP held a meeting to present the maintenance dredging project to defined stakeholders on Aug. 26, 2020. To further inform the public of the project, Communications staff has coordinated with Poseidon Resources LP on information to be posted to the city website and distributed via social media. Staff will post and distribute this information - prior to commencement of the dredging project - and will provide updates as needed during the dredging project. Exhibits 1. Power Point Presentation on maintenance dredging project for Agua Hedionda Lagoon Agua Hedionda Lagoon Outer Basin – Maintenance Dredge and Beach Nourishment 2020/2021 •INTRODUCTIONS ‒Cabrillo in partnership with Poseidon will perform the Agua Hedionda Lagoon (Lagoon) –Outer Basin Maintenance Dredge and Beach Nourishment (AHL-OB MD/BN) ‒Poseidon will manage the AGL-OB MD/BN •Background •Permits •Dredge Volume and Sand Placement •Schedule •Outreach Agenda •Location –City of Carlsbad •Owner of Lagoon –Cabrillo Power I LLC •Lagoon Dredged in 1954 •Outer Basin has been dredged 30 times •Carlsbad Beach Nourishment -North Beach -Middle Beach -South Beach Background •Maintenance Dredge to remove a flood-tide shoal in the Agua Hedionda Lagoon – Outer Basin inlet is needed in order to maintain: The lagoon environment; and Intake water flow for the Claude “Bud” Lewis Carlsbad Desalination Plant. ‒Since 2018, Cabrillo no longer intakes water from the lagoon. Open Inlet Is Critical To A Healthy Lagoon Why Is It Important to Preserve & Protect the Agua Hedionda Lagoon? •Dredge and Beach Nourishment ‒Similar operations have been performed over the last six decades. Dredge and Beach Nourishment quantities have ranged from 159,000 to 429,000 cy. The most recent operation, completed in 2018, accounted for 205,482 cy. ‒All Dredging and Beach Nourishment activities occurs between September 15th thru April 15th, outside the nesting and high beach usage season. Background and Project Overview July 1, 2020 •The work will be performed in accordance with the stipulations in the following permits: ‒City of Carlsbad Special Use Permit (SUP) 06-10X2(A) ‒US Army Corps of Engineers Permit SPL-2001-00328-RRS ‒California Coastal Commission Coastal Development Permit ‒San Diego Regional Water Quality Control Board 401 Water Quality Certification ‒California Department of Parks and Recreation Right of Entry Permit ‒California State Lands Commission Lease PRC 932.1 and PRC 8721.1 Permits July 1, 2020 Sand Deposition Plan –July 2020 ‒Beach Profile Surveys –May 2020 ‒Sand Placement o Re-Establish Sand Equilibrium Profiles o Replace Sand Erosion Since 2018 –295,274 cy o Maximize Recreational Widths in Proportion to Use o Avoid Impact to Sensitive Hard Bottom Habitat Dredge Volume and Sand Placement Dredge Volume, Sand Placement and Schedule Receiver Site Approximate Placement Quantity Approximate Schedule North Beach 200,000 cy November 2020 to December 2020 No.Inlet Jetty to Maple Ave 125,000 cy Maple Ave to Pine Ave 75,000 cy Middle Beach 42,000 cy January 2021 to February 15,2021 South Beach 58,000 cy February 15,2021 to March 20211 Total up to 300,000 cy 1Sand placement operations my extend beyond March 2021 if adverse weather conditions or equipment issues are encountered.No sand will be placed on beaches after April 15,2021. Survey, Plans and Monitoring ‒Pre-and Post-dredge bathymetric surveys & beach profiles: US-ACOE, CofC, CCC ‒Pre-dredge Sand Deposition Plan: CofC ‒Pre-dredge Sampling and Analysis Plan: US-ACOE, CCC, SLC ‒Pre-dredge Caulerpa taxifolia: US-ACOE, CofC, CCC ‒Pre-and Post-dredge eelgrass: US-ACOE, CofC, CCC ‒Pre-and Post-dredge Nearshore Habitat Mapping: US-ACOE ‒Grunion: US-ACOE, CCC ‒Sea Turtle: US-ACOE, NMFS ‒Water Quality Monitoring Plan: SD-RWQCB Surveys, Plans and Monitoring ‒Pre-Project Monitoring Plan; US-ACOE ‒Dredging and Disposal Operations Plan: US-ACOE ‒BMPs: CofC, CA PR ‒Pre-and Post-Notifications and various reports: all agencies ‒Public safety postings and other protections: CofC, CA PR, CCC ‒Timing: Sept. 15 to Apr. 15 cycle for Least Tern nesting season, recreational benefit, etc. •August 26, 2020 -Zoom Stakeholder’s Meeting •Attendees: . •Regulatory Agencies: City of Carlsbad, CADPR, SLC, US-ACOE, CCC •Surfrider Foundation, •HUBBS Seaworld Research Institute, •Carlsbad Aquafarm, YMCA, •California Water Sports, •Agua Hedionda Lagoon Foundation, and •Mary Ann Vinery. No comments were received from the meeting attendees. Outreach •Please send your comments to: ‒Josie McKinley at JMcKinley@Poseidonwater.com Comments