MORGAN HILL
– The company responsible for polluting South County groundwater
will begin to comply with a state water board order to clean up its
former Morgan Hill plant site contaminated with the chemical from
40 years of manufacturing safety flares.
MORGAN HILL – The company responsible for polluting South County groundwater will begin to comply with a state water board order to clean up its former Morgan Hill plant site contaminated with the chemical from 40 years of manufacturing safety flares.
Olin Corp.’s clean-up plan at the Tennant and Railroad avenues site, includes excavating soil with perchlorate levels above 7.8 parts per billion and treating it with perchlorate-eating microorganisms, a process called bioremediation. Soil with levels below 7.8 ppb will not be excavated but will be treated with the microorganisms.
Olin’s statement, issued Friday, predicted the treatment would take about two years to complete.
Cleansing on-site groundwater has been ongoing since March. More than 15 million gallons have been treated to date. Treatment works by extracting water through three wells and running it through an ion exchange system that removes the perchlorate.
Treated water is moved to the Butterfield Retention Pond as permitted by the Regional Water Quality Control Board, the lead government agency in the Olin cleanup.
Olin has installed treatment plants on wells at the West San Martin Water Works and the San Martin County Water District, small municipal systems serving several hundred residents. Water is also treated with an ion exchange system.
Morgan Hill Director of Public Works Jim Ashcraft said Monday that he had no problem with Olin treating its own groundwater and soil but would like to see the company help the city with some off-site wells that show elevated levels of perchlorate contamination.
“The northeast wells are our biggest problem,” Ashcraft said. “Olin says it (the perchlorate in the northeast wells) has nothing to do with them.”
Olin has held fast to the claim that all water flows southeast from its Tennant site and any perchlorate found north of the site is from another source.
While monthly tests have showed perchlorate levels below the detectable 4 ppb at which point the city closes wells, several in the past have spiked and remain shut down leading to occasional serious water shortages.
Olin has paid the City of Morgan Hill $706,000 to replace the Tennant Avenue well, highly contaminated at one time and closed down by the city. A replacement well was built on San Pedro Avenue.
Contaminated water was discovered in January 2003 to have reached into the underground water table and traveled through south Morgan Hill, San Martin east of Monterey Road (largely) and into north Gilroy.
The safe level of perchlorate remains undetermined, but it is known to cause thyroid malfunctions and other serious problems, especially in infants and susceptible adults.
The Perchlorate Citizens Advisory Group (PCAG) will meet from 7 to 9 p.m. tonight at the San Martin Lions Club, 12415 Murphy Ave.
