MORGAN HILL
– It’s not ours, the Olin Corporation says of perchlorate found
north of its former road-flare plant on Tennant Avenue.
MORGAN HILL – It’s not ours, the Olin Corporation says of perchlorate found north of its former road-flare plant on Tennant Avenue.
Nevertheless, under orders from the Central Coast Regional Water Quality Control Board, Olin submitted a plan on Friday to investigate how the northern perchlorate might have gotten there.
Olin has accepted responsibility for perchlorate in groundwater south of Tennant Avenue but contends that, since water is known to flow south in that area, 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 cleanup. “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.”
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.
“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,” McClure said. “We also will investigate whether historical groundwater pumped from the aquifer southeast of the site was used to irrigate land north of the site.”
Olin also has to identify all wells located between the Tennant Avenue site and the city’s Nordstrom well – which tested above 4 parts per billion. for perchlorate – at East Dunne and Murphy avenues. Further, Olin has to propose a monitoring and sampling program that will define the extent of the perchlorate plume in the northern area.
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.
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.
