Orange County to Expand Groundwater Replenishment

The Orange County Water District in California awarded Siemens a $14 million contract to supply a hollow-fiber membrane treatment system as part of the Groundwater Replenishment System expansion.

The 48-million-gallons-per-day membrane system, coupled with an existing Siemens' membrane system, will increase the flow to 134 mgd for the reverse osmosis (RO) membranes downstream in the system. Construction could begin as early as late 2010.

The system produces high quality water for less than the cost of future imported water, while using less energy and therefore fewer gas emissions than required to import water from Northern California.

“We were happy with the membrane technology in our existing system,” says Shivaji Deshmukh, GWR System program manager with the water district, “and we felt that staying with this technology for the system expansion was the most efficient, cost-effective way to go.”

With more than 2.3 million inhabitants, the district’s service area is one of the most populous areas in the United States. The GWR System, a joint project of the water district and the Orange County Sanitation District, was established in 1997 to preserve local groundwater resources and to help form a seawater intrusion barrier. The RO pre-treatment system expansion will consist of Memcor CS membrane modules, ancillaries, control system upgrades, and associated electrical work. Siemens will supervise the membrane modules’ installation and the expanded system’s commissioning. At the time it was installed, the original Siemens membrane system was the largest membrane system in the Americas and one of the largest in the world. Because the system was designed for future expansion, with 20 percent extra space in the existing 26 basins, the water district will add 10 more membrane basins.

The Groundwater Replenishment System, which has been operating since January 2008, is the world’s largest water purification project of its kind. Highly treated wastewater, originally destined for the ocean, is pretreated by submerged membrane modules at a rate of 86 mgd before entering the RO units, followed by ultraviolet and hydrogen peroxide disinfection.

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