Stormwater Engineering Projects

SEAWATER BARRIER PROJECTS

For more information, please click on a barrier project below.

Picture of West Coast Basin Barrier

ANNOUNCEMENTS

  • Project presented at the Manhattan Beach City Council Meeting on 6/18/19
  • Project presented at the Hermosa Beach City Council Meeting on 7/23/19
  • Community Meeting held in the City of Hermosa Beach on 10/28/19
  • Community Meeting held in the City of Manhattan Beach on 11/6/19
  • Construction started on 04/05/21

BACKGROUND

The West Coast Basin Barrier Project (WCBBP) was designed and constructed in the early 1950's to prevent seawater from intruding into the underlying aquifers of the West Coast Groundwater Basin in the County of Los Angeles. The WCBBP is one of three seawater barriers that Public Works operates to prevent seawater from contaminating the groundwater by injecting freshwater to form a protective pressure ridge. Over five million residents of the Southern California Coastal Plain depend on this groundwater that provides up to 40 percent of the drinking water supply.

PROJECT SUMMARY

Public Works proposes to construct 11 injection wells and one monitoring well to replace and supplement existing WCBBP facilities located within the Cities of Manhattan Beach and Hermosa Beach. Nine injection wells will be constructed to replace existing injection wells that are beyond their useful life and require immediate replacement. Two new injection wells will be constructed at locations in-between existing injection wells along the WCBBP to increase the integrity of the barrier and provide increased protection against seawater intrusion. Prior to constructing the new wells, the existing injection wells will be properly sealed to prevent the possibility of subsidence and/or groundwater cross contamination. Once the new injection wells are brought online, they will help prevent seawater intrusion by creating a freshwater pressure ridge in the underlying aquifers of the West Coast Basin located in the County of Los Angeles. The new observation well facility will increase Public Works' ability to monitor groundwater elevations and chloride concentrations for the region's underground aquifers and will improve overall operational efficiency of the WCBBP.

Construction is currently planned to start April 2021 and finish April 2022.

PROJECT DETAILS

CONTACTS

For more information on the project please contact swb@dpw.lacounty.gov



Picture of West Coast Basin Barrier

ANNOUNCEMENTS

  • Virtual Community Meeting presented to Leisure World Community (City of Seal Beach) on 06/29/21

BACKGROUND

The Alamitos Barrier Project (ABP) was designed and constructed in the early 1960s to prevent seawater from intruding into underlying aquifers of the Central Basin of Los Angeles County and the Coastal Plain of Orange County. The ABP is one of three seawater barriers that is operated by Los Angeles County Public Works to prevent seawater from contaminating the groundwater by injecting freshwater to form a protective pressure ridge. Over six million residents in Los Angeles County and Orange County depend on the groundwater from the Central Basin and Coastal Plain as a source of drinking water supply.

PROJECT SUMMARY

Public Works proposes to construct 5 injection wells and 2 monitoring wells to replace and supplement existing ABP facilities located within the Cities of Long Beach and Seal Beach. The five injection wells will replace existing injection wells that are beyond their useful life. Two of the injection wells will be constructed in the City of Long Beach and the other three injection wells will be constructed in the City of Seal Beach on the Los Angeles Department of Water and Power (LADWP) Haynes Generating Station. Prior to constructing the new wells, the existing injection wells will be properly sealed to prevent the possibility of subsidence and/or groundwater cross contamination. Once the new injection wells are brought online, they will help prevent seawater from intruding into the underlying aquifers of the Central Basin in Los Angeles County and the Coastal Plain of Orange County. The two new monitoring wells in the City of Seal Beach (also on the LADWP Haynes Generating Station) will enhance Public Works' ability to monitor groundwater elevations and chloride concentrations for the region's underground aquifers that are being protected by the ABP. This new groundwater and chloride data will help optimize injection rates at adjacent ABP injection wells.

Construction is currently planned to start February 2022 and finish October 2022.

PROJECT DETAILS

CONTACTS

For more information on the project please contact swb@dpw.lacounty.gov

Updated on: 07/01/2021