Groundwater demineralization plant recognized as 'Membrane Plant of the Year'

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CONCORD, CA, Mar. 7, 2012 -- The Zone 7 Water Agency (Livermore, CA) recently received the "2012 Membrane Plant of the Year" Award from The Southwest Membrane Operator Association (SWMOA) for their Mocho Groundwater Demineralization Plant. The facility, which began operating in 2009, uses reverse osmosis to reduce salt and mineral buildup in the Livermore-Amador Valley Main Groundwater Basin.

Water-related engineering firm Carollo Engineers worked alongside the Zone 7 Water Agency to construct the plant. As part of the project, Carollo also designed a 28-inch diameter high-density polyethylene pipeline which was constructed to convey water from four separate wells into the Mocho Groundwater Demineralization Plant.

During the treatment process, the agency employs reverse osmosis, a method used to remove dissolved salts from water. After, the treatment process produces a very soft permeate water which is further treated by a decarbonation process before being disinfected and chemically treated to prevent corrosion. The process also produces a rejected brine stream (containing the removed salts), which is collected for disposal.

Currently, the Mocho plant operates at 80 percent efficiency, turning 6.1 of the 7.7 mgd raw water pumped through its system into softened permeate. Eventually, the facility will be able to increase its efficiency to 85 percent. This unique process was a vital piece to the agency's award submission.

SWMOA's Membrane Plant of the Year award honors public or private facilities providing water, wastewater or reclaimed water which show exemplary safety records and clean premises, possess minimal permit violations, utilize their plant to educate the public and have at least 1 million gallons per day (mgd) of membrane based treatment processes.

"SWMOA is a Membrane Plant Operators Association, so the award is really about the terrific job that the plant staff does," said Tom Seacord, Associate Vice-President, Carollo Engineers Inc. "It was a great pleasure working with the Zone 7 staff during the design and construction of this facility. For a design to be successful, you need the input of the owner and operations staff. This allows the design to be the most responsive to their needs. Zone 7's staff gave our design team this integral support."

Both Carollo and the Zone 7 Water Agency are committed to improve water and wastewater sustainability. With this joint effort, the plant is able to continuously provide a sustainable supply of high-quality drinking water to Livermore Valley through demineralization -- a process which will soften about 29 percent of the zone's groundwater pumping capacity and remove 4,000 tons of salt per year -- and enable the use of recycled water for irrigation purposes.

"We are thrilled about being named SWMOA's 'Plant of the Year'," says Rich Gould, Water Production Superintendent, Zone 7 Water Agency. "But most importantly, we are excited to be able to successfully provide all of our communities with high-quality and safe drinking water. We look forward to increasing our efficiency at the Mocho Groundwater Demineralization Plant and to continue using cutting-edge techniques to effectively manage water resources."

As an affiliate of the American Membrane Technology Association, SWMOA is dedicated to serving the Southwest United States and improving the quality of water supplies through desalting, reuse and other water sciences. For more information on the award, please visit

About Zone 7 Water Agency
Zone 7 Water Agency is one of the 10 active zones of the Alameda County Flood Control and Water Conservation District. The District was established by the State Legislature in October 1949 to solve problems of flooding, drainage, channel erosion and water supply and conservation in Alameda County. In 1957, by popular vote, Zone 7 became a special district governed by a seven-member board of directors. Along with flood protection, Zone 7 supplies water to all of eastern Alameda County and a population of more than 200,000. Treated water is sold wholesale to local retailers, including the cities of Livermore and Pleasanton, the Dublin San Ramon Services District and the California Water Service Company. Zone 7 also distributes untreated water to local agriculture operations and golf courses.

About Carollo Engineers
For more than 75 years, Carollo Engineers has provided a full range of innovative planning, design and construction management services to meet the water and wastewater needs of municipalities, public agencies, private developers and industrial firms. To learn more about how Carollo is Working Wonders With Water®, call (800)523-5826 or visit


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