Date: April 29, 2003

Water district purchasing treatment plant to help ease perchlorate contamination in South Santa Clara County

SAN JOSE - The Santa Clara Valley Water District board of directors today agreed to buy a portable water treatment plant to help remove perchlorate from drinking water supplies in South Santa Clara County's groundwater basin.

Within the next three months, the district expects to install a treatment system that filters water from a well through tanks filled with resin beads - a process known as ion exchange - to rid the water of perchlorate. The treatment plant will be installed initially on an existing municipal well in Morgan Hill that was closed in 2002 when low levels of perchlorate were discovered. The plant could also be relocated to treat water elsewhere in South County.

"We're spending this money as part of a multi-agency effort to provide residents with clean, safe water," Sig Sanchez, chairman of the district board of directors, said referring to a coalition comprised of the district, the cities of Morgan Hill and Gilroy, and the county.

"This will help the city ensure enough water for its residents when demand peaks in the summer. And there's a subsequent benefit to the rest of South County in that the perchlorate we pump from up north results in that much less that can make its way south into San Martin and Gilroy."

The ion-exchange system, manufactured by Calgon Carbon Corp., is expected to cost about $1 million to purchase and install. The board approved an expenditure of as much as $1.05 million for the purchase, installation, start-up and initial operation of the treatment plant.

The self-contained, skid-mounted treatment system consists of two tanks filled with resin beads. As water circulates through the tanks, charged perchlorate ions stick to the resin and pick up chloride. When the resin beads are exhausted, Calgon will remove and dispose of the spent resin and replace it with new beads.

The Calgon ion-exchange system was used in Baldwin Park to clean an eight-mile plume of perchlorate in San Gabriel Valley left over from rocket-testing decades ago by AeroJet. It is also being used elsewhere in California to clean perchlorate from drinking water supplies.

A 7.5-mile-long plume of perchlorate flows from southern Morgan Hill to northern Gilroy, the legacy of a roadside flare-manufacturing firm owned by Olin Corp. that operated from the mid-1950s until 1996 at the northeast corner of Tennant and Railroad avenues.

The board's unanimous vote is based on the expectation that Olin Corp. will eventually reimburse taxpayers for the cost and operation of the ion-exchange treatment plant. Under state law, costs for cleaning up contamination rest with the property owner, Olin.

Investigation of the contamination and cleanup efforts by Olin are proceeding under the direction of the Central Coast Regional Water Quality Control Board. The water district is assisting the Regional Board.

As of April 17, perchlorate has been detected in 389 of 1,006 wells sampled by the water district and by a consultant under contract with Olin Corp. All but a handful of the wells show very low levels of the contaminant.

The coalition of public agencies - known as the City Managers' Working Group - was formed recently to advise the Regional Board as it directs Olin's efforts to clean up perchlorate contamination.

The Santa Clara Valley Water District manages Santa Clara County's wholesale drinking water resources, coordinates flood protection for its 1.7 million residents and provides stewardship for the county's 10 reservoirs and more than 700 miles of streams.