Contaminant found is four to nine times higher than public
health goal
San Martin – Higher-than-expected levels of perchlorate have seeped into the groundwater deep below San Martin, water officials reported. But the new evidence shouldn’t delay cleanup plans for road-flare manufacturer Olin Corporation.
Detections of perchlorate at 54 parts per billion at a depth of 386 feet were reported by Olin in August at a well south of Middle Avenue and west of Murphy Avenue in San Martin.
The company also reported detections of 24 parts per billion at a depth of 345 feet at a well further south in San Martin.
Those levels far surpass the new legal state threshold of 6 parts per billon for perchlorate in drinking water that went into effect Thursday.
The new readings are somewhat perplexing, and will require more study, said Hector Hernandez, an engineer for the Central Coast Regional Water Quality Control Board. But existing cleanup plans for Olin should proceed without delay, Hernandez said.
“These readings are higher than they expected and they are going to cause some complications,” Hernandez explained, adding Olin will now need to take more time to map out the extent of perchlorate contamination stemming from its defunct Morgan Hill road flare plant.
The latest draft of Olin’s cleanup order spells out the additional work needed, causing some San Martin residents and local water officials to worry about groundwater cleanup taking longer than expected.
“We’re hoping it won’t,” Hernandez said. “My position is this should not hold up the cleanup in the intermediate aquifer zone (depths of 75 to 220 feet).”
Olin is responsible for a 10-mile plume of perchlorate stretching south of Morgan Hill, where the company operated a road flare plant from 1956 to 1995. State regulators have been directing a massive cleanup effort since perchlorate contamination was discovered at the factory in 2000.
The latest draft of the cleanup order is scheduled to go before the Central Coast Regional Water Quality Control Board Dec. 7.
Perchlorate is a salt believed to harm pregnant women and other members of the population if ingested at high enough quantities.
Dozens of San Martin residents continue to receive bottled water from Olin as the cleanup effort continues.
San Martin resident Sylvia Hamilton, who chairs the Perchlorate Community Advisory Group (PCAG), said the cleanup order should be more to the point.
“The order should spell out all of the deadline dates and what the expectations are,” Hamilton said Wednesday. “This order is critical to the long-term cleanup of the groundwater.”
Hamilton said she would lead a discussion on the draft order at a special PCAG meeting at 7pm, Thursday at the San Martin Lions Hall, 12415 Murphy Ave.
A public comment period on the document ends Nov. 2, and Hamilton said the public is encouraged to attend and provide input for a group letter to water regulators.
“This is our opportunity to have our voices heard before this order is put in place” in December, she said.
Santa Clara Valley Water District official Tracy Hemmeter said she hopes the new cleanup order means Olin will still be required to begin active remediation of the area directly south of Morgan Hill within the original two-year timeline set last year.
“The water district’s general comment is, this order doesn’t meet our goal of a time certain, comprehensive cleanup,” Hemmeter said. “There’s no specific date for the pumps getting turned on.”
Hernandez said while the complete timeline is not included in the order, per se, other documents spell out the general course of action.
At this point, it will take Olin another two years to obtain permits and infrastructure needed to begin extracting water from the ground, cleaning it, and re-injecting it.
“The work is beginning as we speak,” Hernandez said. “Olin completed soil cleanup at the site, and there are 14 domestic wells in San Martin with ion exchange systems. We’re hoping the board will agree with the proposed cleanup order in December so we can keep moving forward.”
