Olin Corp. has issued possible explanations of its Oct. 10 plan
to investigate why perchlorate has been found north of its former
road flare plant on Tennant Avenue. The state Central Coast
Regional Water Quality Control Board ordered the company to submit
the plan.
Olin Corp. has issued possible explanations of its Oct. 10 plan to investigate why perchlorate has been found north of its former road flare plant on Tennant Avenue. The state Central Coast Regional Water Quality Control Board ordered the company to submit the plan.
The Regional Board is the state agency in charge of the Olin-caused contamination of more than 400 wells from Morgan Hill, through San Martin to north Gilroy, discovered in January to have spread widely throughout the area.
Olin is to identify all wells within one-fourth mile of either side of a line between the Tennant Avenue site and the city’s Nordstrom well at East Dunne and Murphy avenues. Further, Olin is to provide data from those wells within the line that have been tested for perchlorate and propose a monitoring and sampling program that will define the extent of the perchlorate plume in the northern area.
Olin has accepted responsibility for perchlorate in groundwater south of Tennant Avenue where its now-closed flare plant was located but has maintained that, since water is known to flow south, northern perchlorate must come from elsewhere.
“After extensive investigation of our property and the surrounding area, no information indicates that groundwater from our property has gone in a northeast direction,” said Rick McClure, Olin project manager for the Tennant Avenue clean-up.
“All the information we have indicates a south/southeast groundwater flow pattern. In the interest of putting this issue to rest, Olin has developed a plan to further investigate groundwater flows in the area to the northeast of Olin’s property,” McClure said.
“Among other things, the plan provides for an investigation of whether past or current pumping of groundwater occurred in a magnitude and duration sufficient to have caused groundwater to move in a northeast direction, rather than to the south-southeast as it normally flows. We also will investigate whether historical groundwater pumped from the aquifer southeast of the site was used to irrigate land north of the site.”
The work plan will evaluate hydrogeologic data from the Santa Clara Valley Water District and the state Department of Water Resources to see if there are circumstances under which the chemical would move north from the Olin site.
The company has 90 days after the Regional Board’s approval of the work plan to report its findings. Olin also expects to report, by Oct. 30, on findings from its study of perchlorate in the underground aquifers south of the site, through southeastern Morgan Hill and San Martin.
Olin continues to provide bottled water to close to 1,400 residents who get their water from wells with perchlorate levels above 4 parts per billion.
