EXPANDING LOCAL WATER SUPPLY
The Regional Brackish Water Reclamation Program (RBWRP) seeks to reclaim the historical brackish water plume in the West Coast Groundwater Basin and create a new local drinking water supply.
This regional effort will use new groundwater extraction wells, desalination and state-of-the-art technology to purify the salty water and use it for distribution through local municipal drinking water systems. The new regional groundwater desalter facility will use reverse osmosis to remove the salts from the water and will provide up to 20,000 acre-feet (over 18 million gallons per day) of high-quality drinking water to local water customers.
The removal of salty groundwater will in turn create available groundwater storage capacity for excess local freshwater and recycled water. Local water providers will be able to store surplus water for use during dry years—thus creating drought-resiliency for generations to come.
THE HISTORY OF BRACKISH WATER IN THE GROUNDWATER BASINS
Groundwater over-pumping in the early 1900s lowered groundwater levels to below sea level along the coast (see the info-graphic below). This resulted in saltwater flowing into, or “intruding” into the groundwater aquifers. As the seawater mixed with the freshwater aquifers, the groundwater became “brackish,” or too salty for drinking.
Groundwater production wells in the West Coast Basin and in the southeastern tip of the Central Basin were affected, and water producers had to consider abandoning their wells.
In response, the courts legally limited groundwater extraction for the basins and LA County constructed seawater barrier injection wells starting in the early 1960s. The wells actively pump freshwater into the ground, thereby creating a water pressure “barrier” to keep seawater out of the aquifers. The Seawater Barrier system now consists of over 100 injection wells located along the coast and effectively protects the aquifers from seawater contamination.
While the Seawater Barrier system was an overall success, saving many wells, it trapped a plume of brackish groundwater inland from the barrier injection wells. This 600,000-acre-foot (20-billion-gallon) plume still exists today, rendering groundwater pumping unfeasible in certain West Coast Basin areas.
TRIED AND TESTED
WRD’s experience in brackish groundwater reclamation started with the Robert W. Goldsworthy Desalter, located in the City of Torrance. The Goldsworthy Desalter was commissioned in 2001 and expanded in 2018. The facility now treats 5 million gallons per day (mgd) of salty groundwater extracted from the brackish plume in the West Coast Groundwater Basin using reverse osmosis technology. The plant is owned by WRD and operated by the City of Torrance. The treated water produced by this facility is added to the water distribution system for the City of Torrance and meets 25% of the city's water needs.
WRD, working in partnership with seven regional stakeholders that pump groundwater or distribute drinking water within the basin will take the best practices and expertise from the small-scale Goldsworthy Desalter project and apply them to the future large-scale Regional Brackish Water Reclamation Program desalter project.
HOW IS BRACKISH GROUNDWATER TREATED?
Groundwater desalination works primarily through the use of reverse osmosis treatment. Salty brackish groundwater extracted from wells is forced through reverse osmosis membranes to remove the salts in the water. The water is then disinfected and the pH level is adjusted to create fresh, potable water.
Program Feasibility Study
WRD has recently completed a Feasibility Study and will be moving into the piloting, permitting, and environmental process in late 2021. A copy of the Final Feasibility Study and two follow-up addenda regarding project refinements and a new project site are available for download below.
- Click here to download The Feasibility Study Report
- Click here to download Addendum No. 1, Project Component Refinements
- Click here to download Addendum No. 2, New Desalter Site Assessment
Next Steps for the Regional Brackish Water Reclamation Program:
- RFP's for Piloting and Environmental Review will be released in 2021; for additional info contact Mario Bautista at Mbautista@wrd.org