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The Groundwater Replenishment System
Final Expansion Project

A Report on OCWA’s January 2021 Webinar

By Tim Hogan
OCWA Communications

After all the success and accolades the Orange County Water District has seen for its Groundwater Replenishment System, there seemed only one way left to improve it: make it bigger. And with the expansion project currently underway, the District will realize almost a 33% increase in production of purified water. It will mark a major advancement for an already widely acclaimed system.

To learn more about the status of the expansion, OCWA was honored last month to host the GWRS Program Manager, Sandy Scott-Roberts, PE, for the first of our monthly Industry Insight webinars for 2021. Her presentation was underwritten, in part, by two of our Corporate Sponsors for 2021, Black & Veatch and John Robinson Consulting. Well over 100 people enjoyed the presentation.

Formed by the California Legislature in 1933, and tasked with the responsibility to manage the County’s groundwater basin, OCWD has grown over the years to include 19 municipal and special water districts. It presently provides 77% of the water supply for north and central Orange County, a customer base of more than 2.5 million people.

As part of its commitment to provide reliable, high quality water, OCWD has long sought to ways to increase the supply in the local aquifer. The GWRS was proposed as a cost efficient means to create more water in an environmentally responsible manner. For what could be more beneficial in so many different ways than to process the county’s wastewater into purified water that could be used to replenish the aquifer?

The GWRS accomplishes this by taking highly treated wastewater from the Orange County Sanitation District, then processes it through a series of technologies — micro-filtration, reverse osmosis, and ultraviolet light. The now-potable water is then sent both to recharge basins along the Santa River, and injected through a series of wells to help bolster the country’s seawater barrier.

Currently, the GWRS receives its influent from the adjacent OCSD Plant No. 1. To expand its capabilities, however, a second OCSD Plant is being constructed further downstream on the Santa Ana River. When completed, influent from this plant will be piped upstream for processing at the GWRS.

The water from OCSD Plants 1 and 2 will be of substantially different composition. Where Plant 1 influent is a combination of activated sludge and trickling filter secondary treatment, Plant 2 influent will be trickling filter solids and contactor secondary effluent. Because of this difference with the influent water, the expanded GWRS facility has been designed to address the higher TDS and increased alkalinity and ammonia content of the combined influent.

The design for the expanded facility was completed in February 2019, and construction begun by Shimmick Construction Company in November of that year. Construction is expected to be completed in February 2023. The project budget is expected to come in at around $293 million.



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OCWA was pleased to host this timely presentation by Sandy Scott-Roberts. Her well-received talk continued into the New Year the exceptional standard which OCWA is committed to provide in our Industry Insight webinar series. For despite the disruptions the Covid-19 pandemic has plagued us with, the OCWA Board of Directors remains committed to providing quality, timely information for the Association’s members, as well as the entire Orange County water community.

For those interested, a PDF of Ms Scott-Robert’s PowerPoint presentation is available for download by OCWA’s members only. Yet another great reason to consider becoming a member if you aren’t one already.

The February Industry Insight Webinar promises to be equally enlightening. Rosanne Weston, PMP, Engineering Manager, Yorba Linda Water District, will address the Design of Yorba Linda Water District’s New 19 MGD PFAS Treatment Plant, the first operational facility in Orange County to deal with the emerging issue of PFAS.

Register Now to Ensure You Don’t Forget!
OCWA Members: Free. Non Members: $10.00

So join us, February 17, to learn how to use your assets wisely while you protect their useful life.

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