GWRS final expansion

The Groundwater Replenishment System Final Expansion (GWRSFE) project will increase the system treatment capacity from 100 to 130 million gallons per day (MGD).

Groundwater Replenishment System Final Expansion Project Fact Sheet

In order to produce 130 MGD of purified water through the GWRS, additional secondary effluent from the Orange County Sanitation District (OCSD) is required for source water.  This additional secondary effluent source water must be received from OCSD’s Treatment Plant Number 2 (OCSD P2) which is located in the city of Huntington Beach approximately 3.5 miles south of the GWRS facility.  The GWRSFE project will include expanding the GWRS treatment facilities, constructing new conveyance facilities at OCSD P2, and rehabilitating an existing pipeline between OCSD P2 and the GWRS.

OCWD and OCSD commit to the following items, per the Second Amended and Restated Joint Exercise of Powers Agreement for the Development, Operation and Maintenance of the Groundwater Replenishment System and Green Acres Project, which was approved at the November 16, 2016 board meeting:

  • OCSD will continue to provide secondary effluent for GWRS source water free of charge
  • OCSD will continue to allow OCWD to discharge brine free of charge
  • OCWD will pay for the total estimated cost of $292,118,000 for the GWRSFE project
  • OCSD will manage the OCSD P2 Headworks Segregation Project; OCWD will reimburse OCSD with $50,000,000 for project costs
  • OCSD will lease approximately 10 acres of land to OCWD at $1 per year for the GWRSFE project
  • OCSD will allow OCWD to discharge North and South Basin extraction well flows to OCSD sewers
  • OCSD will continue to complete projects to divert up to approximately 8 MGD from the Santa Ana Regional Interceptor (SARI) line of additional secondary effluent for treatment at the GWRS
  • OCSD will provide power and communications conduit to and from OCSD P2; OCWD will reimburse OCSD for power costs
  • OCWD secured a Water Infrastructure Finance and Innovation Act (WIFIA) loan from the U.S. EPA for $135 million

The table below lists all projects required for the GWRS Final Expansion and their estimated costs: 


Projected Budget







Design Engineering Services (B&V)


Construction Management/Inspection


CM Agreement (Butier/Carollo)         


Specialty/Materials Construction Inspection


Total CM and Inspection 




AWTF Expansion Construction


P2 Effluent Pump Station Construction


P2 Flow Equalization Tank Construction


P2 Pipeline Rehabilitation Construction


Total Construction Phase


Engineering Support, Legal & Administration 


Process Support Agreement (SPI)


Legal/Admin/Engineering Support


Total ELA




Construction Contingency


OCSD Project


OCSD Headworks Modification Project




The GWRSFE project construction contract was awarded at the September 4, 2019 Board of Directors Meeting. Construction is scheduled to begin during fourth quarter 2019.  Please contact Sandy Scott-Roberts or Kathryn Demesa if you have any questions or for additional information on the GWRSFE project.