HomeMy WebLinkAbout2020-08-20; 2020-21 Agua Hedionda Lagoon Outer Basin Maintenance Dredging Project; |Barberio, Gary| Lancaster, Kyle|To the PTlemlters of the:
CITY COUNC'7 /
Date~A V CC v
CMLACM~M (3)~
Aug.20,2020
Council Memorandum
To:
From:
Via:
Honorable Mayor Hall and Members of the City Council
Gary Barberio, Deputy City Manager, Community Services
Kyle Lancaster, Parks & Recreation Dire~
Geoff Patnoe, Assistant City Manager 0"
{cityof
Carlsbad
Memo ID# 20201 73
Re: 2020-21 Agua Hedionda Lagoon Outer Basin Maintenance Dredging Project
The purpose of this memo is to provide an update on the 2020-21 maintenance dredging of
Agua Hedionda Lagoon (lagoon), to be conducted by Poseidon Resources LP and Cabrillo Power
I LLC.
Background
Since 1994, maintenance dredging projects have been conducted at intervals of one to four
years to remove a flood-tide shoal that forms in the 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 Desal.ination 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.
Discussion
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 the lagoon in order to maintain. tidal exchange between the
lagoon and ocean. Similar operations have been performed over the last six decades.
Approximately 300,000 cubic yards (cy) of sand may typically be removed from the lagoon
outer basin. 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.
Community Services Branch
Parks & Recreation Department
799 Pine Avenue, Suite 200 I Carlsbad, CA 92008 I 760-434-2826 t
Honorable Mayor Hall and Members of the City Council
Aug.20,2020
Page 2
Sand placement quantities for each receiver beach will be determined based on the conditions
reflected in a beach profile survey conducted within 45 days of the commencement of the
dredging project. The results of the survey will be incorporated into the sand deposition plan
for the three beaches (i.e., north, middle and south}, and the maintenance dredging project will
be conducted accordingly. 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, ttie
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
Staff and Poseidon Resources LP will present an informational report on the maintenance
dredging project to the Beach Preservation Commission at its next regular meeting on
Oct. 6, 2020. Additionally, Poseidon Resources LP plans to hold 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.
cc: Scott Chadwick, City Manager
Celia Brewer, City Attorney
Paz Gomez, Deputy City Manager, Public Works
Robby Contreras, Assistant City Attorney
Ronald Kemp, Assistant City Attorney
Allegra Frost, Deputy City Attorney
Jeff Murphy, Community Development Director
Kristina Ray, Communications & Engagement Director
Babaq Taj, Engineering Manager