Guest Editorial: Critical Success Factors at OCWD’s Groundwater Replenishment System

Mike Markus  OCWD General Manager

Michael Markus OCWD General Manager

The GWRS takes secondary treated wastewater and further treats it using microfiltration, reverse osmosis and ultraviolet light with hydrogen peroxide to produce water that is of near-distilled quality. The process removes any bacteria, protozoa, dissolved minerals, viruses, pharmaceuticals and low molecular weight organics to non-detection levels. At 70 million gallons per day (mgd), this project is the largest planned indirect potable reuse project in the world and its success has led other agencies to look at indirect potable reuse as a means to augment their water supplies.

Two key factors have led to the success of the project. The first being the partnership between OCWD and the Orange County Sanitation District (OCSD) and the second being the OCWD’s public outreach program.

The partnership between the two agencies really began in the 1970’s when OCWD built the Water Factory 21, which was the first plant in the world to use reverse osmosis to purify wastewater. Then in the 1990’s with the GWRS, once again the agencies came together and by jointly constructing the GWRS eliminated the need for OCSD to build a second ocean outfall. The agencies continue to collaborate as demonstrated by OCSD’s commitment to maintaining an aggressive source control program and producing a high quality secondary effluent, which enables OCWD to efficiently produce its highly purified water. Coordination and cooperation between the wastewater and water agencies is essential for the success of these types of projects.


The other key factor for success is an effective public outreach program. These programs are imperative and must be implemented at the very beginning of the project. Our Board had the vision to identify this as a key to success and created an outreach program as a first order of business. By obtaining letters of support from the retail agencies that would be drinking the water and then obtaining support from local, state and federal elected officials, a strong base of support was created early on. Other important stakeholders included the environmental, health, regulatory, business and minority communities. By being open and transparent early and continually through the process, the project went online and continues to operate without any public opposition.

During the first 4 years of operations the facility has operated extremely well. One of the main challenges of operating the plant occurred during the first two years of operations. During this time the GWRS had to be operated to match the diurnal flows from OCSD’s plant because OCSD had not completed a pump station which would divert additional flow at night so that the GWRS could operate at a constant 70 mgd. As a result, the GWRS had to ramp down to 20 mgd at night and then up to 70 mgd during the day. The operators had to pay very close attention to how much flow was available from OCSD and make adjustments to the GWRS output. The ramping up and down of the plant also caused problems with the lime system, but these problems were all handled and the operators squeezed as much production out of the plant as they could. There still is a small nighttime deficit, but the plant consistently operates at 65 mgd and will produce the targeted 72,000 acre-feet of production this year.

The success of the facility has led OCWD to expand the facility after only 4 years of operations. A contract has been awarded for the GWRS Initial Expansion, which will expand the facility from 70 mgd to 100 mgd. The Initial Expansion will be completed in October 2014.

Michael Markus serves as the General Manager for Orange County Water District.