Final Expansion of OCWD’s Groundwater Replenishment System Underway

As the world’s largest advanced water purification system for potable reuse the Groundwater Replenishment System (GWRS), a joint project of the Orange County Water District (OCWD) and the Orange County Sanitation District (OCSD), is currently treating some 100,000 acre-feet per year (AFY) of wastewater to create new water supplies to serve north and central Orange County. Last week the OCWD’s Board of Directors awarded the contract for construction of the final expansion of 30-million gallon per day (mgd) of the world-renowned GWRS to Shimmick Construction Company Inc. of Irvine, CA.

The final expansion will bring the total production of the GWRS to 134,000 AFY, enough water for one million people. Construction is estimated to be completed in 2023 at a cost of more than $200 million.

“OCWD continues to invest in expanding the GWRS because it significantly increases local water reliability and quality for the 2.5 million people we serve in north and central Orange County,” said OCWD President Vicente Sarmiento. “The GWRS has helped weather multi-year droughts and has decreased the region’s dependence on imported supplies. Prior to coming online, the 19 water retailers OCWD serves could pump 62 percent of their water supply from OCWD’s groundwater basin and, today, because of the GWRS they pump 77 percent. Our investment in this drought-resilient water supply project continues to pay off, while also serving as a model project for the rest of the world.”

The initial 70-mgd GWRS project came online in 2008, followed by a 30-mgd expansion in 2015. To create the potable water OCSD first treats the incoming wastewater and produces water clean enough to undergo purification at the GWRS. Were it not for this process the wastewater would instead of be discharged into the Pacific Ocean.

The water is then purified at the GWRS using a three-step advanced process of microfiltration, reverse osmosis and ultraviolet light with hydrogen peroxide. This cleansed water meets and exceeds state and federal drinking water standards. This purified water is then injected into a seawater barrier and pumped to recharge basins where it naturally percolates into the Orange County Groundwater Basin. The basin is managed by OCWD and the purified water supplements Orange County’s drinking water supplies for one-third of the water that is put into the basin.

“We are proud of our partnership with OCWD, which has been in place for more than 40 years,” said OCSD Chairperson David Shawver. “Our two agencies have made history together and continue to do so with the GWRS Final Expansion. This expansion will allow us to recycle 100 percent of OCSD’s reclaimable wastewater, which will be yet another first in the wastewater and water recycling industry.”

Funding for the final expansion of the GWRS comes from several grants and low-interest loans for capital projects. OCWD secured $135 million from the Environmental Protection Agency’s Water Infrastructure Finance and Innovation Act (WIFIA) program. The project also received $1.1 million in grants from the U.S. Department of the Interior Bureau of Reclamation Title XVI Water Infrastructure Improvements for the Nation (WIIN) program. The GWRS’s Final Expansion was honored to receive the highest ratings for all North Orange County projects submitted through the Integrated Regional Water Management (IRWM) program for Prop 1 grant funding. This program is managed by the California Department of Water Resources and the project is slated to receive $3.6 million in grants through the IRWM program.

The Clean Water State Revolving Fund (SRF) Loan program is expected to provide the remaining $186 million needed by the GWRS Final Expansion. OCWD anticipates it will receive the final agreement for the SRF Loan by mid to late October and prior to issuing the Notice to Proceed for the project.

The internationally renowned GWRS has earned more than 50 awards as a celebrated engineering project. It is a tribute to the partnership of OCWD and OCSD, their people and their contracted partners.

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