Company behind South County perchlorate contamination wants to
clean groundwater basin to 11 parts per billion
– double the state’s health goal
Morgan Hill – The Olin Corp. has proposed a cleanup goal for South County’s groundwater basin that is nearly twice the state’s public health goal for perchlorate and higher than the cleanup level demanded by the state water code.
In a report to the Central Coast Regional Water Quality Control Board, Olin stated that a perchlorate “concentration of 11 ppb is most certainly protective of all members of the population including the most sensitive receptor, the pregnant woman and her fetus.” California’s health goal for the contaminant, a salt known to interfere with thyroid activity, is 6 parts per billion.
“It’s a valid number, based on scientifically sound and technically competent analysis,” Olin project manager Rick McClure said Wednesday of his company’s cleanup goal. “According to the calculations, that number is protective of human health and the environment.”
McClure added that 11 ppb is a preliminary figure that will change based on the logistics and expense of cleaning the groundwater, the water board’s enforcement efforts, and a drinking water standard for perchlorate due to be set by the California Department of Health Services.
He said the company can’t comply with the water code requirement to clean pollution to background levels because it’s not clear how much perchlorate was in the groundwater basin before it was contaminated by Olin’s now-closed road-flare factory in Morgan Hill. Olin operated the plant from 1955 to 1987.
By the time the factory closed in 1995, more than 1,000 wells had been polluted. The water supply for Morgan Hill’s 36,000 residents is also contaminated, though Olin has not assumed responsibility for that pollution and has not been ordered to clean what’s known as the northeast flow.
“It is a preliminary number because there are requirements we can’t fully comply with because a background level has not been established,” McClure said. “It’s likely to change, and in fact, could go up.”
Olin’s cleanup goal is based largely on a January 2005 report by the National Academy of Sciences that set a safe perchlorate reference dose that translates to roughly 24 parts per billion. Weeks later, the U.S. Environmental Protection Agency changed its maximum contaminant level for perchlorate from 1 ppb to 24.5 ppb.
“I’m not surprised that Olin would leverage the NAS study to support a cleanup level,” said Tom Mohr, perchlorate project manager for the Santa Clara Valley Water District. “[The level] will seem outrageous to people who have only heard about 6 ppb, but it’s the middle of the road between the EPA and the California public health goal. I’m afraid this will lead to a lot of controversy and outrage; we still believe Olin should clean up to background levels.”
Sylvia Hamilton, chairwoman of the Perchlorate Community Advisory Group, a committee of water experts, real estate agents, farmers and residents that convened to guide cleanup efforts, had sharp criticism for Olin’s report.
“I’m not going to say I’m surprised, but I don’t like it,” Hamilton said. “The people in this community did not contaminate their groundwater. They did not do this. The background level before this took place was nowhere near 11 ppb. It’s only fair that this gets cleaned up and things get back to where they were before the contamination.”
Last week, the EPA set a federal cleanup standard of 24.5 ppb, but the Olin site is subject to California law, which is much stricter.
Last year, the State Water Resources Control Board, in a ruling that allowed Olin to suspend bottled water to residents whose well water tested at or below the health goal, said the health goal should not supercede a background cleanup level. Hector Hernandez, the regional water board engineer overseeing cleanup of the Llagas sub-basin, said he will press Olin to comply with the water code.
“The cleanup level will be based on groundwater quality,” Hernandez said. “Not on health-based standards, but on degradation of water quality. The goal is background.”
While the background level is still an open question, it seems unlikely, based on current evidence that it was 11 ppb or higher. In recent testing only 34 of 850 wells were contaminated above 6 ppb, and the handful of wells that tested above 10 ppb were within a mile or so of the Railroad Avenue factory site. The company has already installed cleaning systems on the supply wells most affected.
“Based on the information we have available at this time, I would say no,” Hernandez said of the 11 ppb mark. “If they can demonstrate that, I’d like to see it.”
Hernandez said his agency will reserve final judgment on the cleanup level until at least this summer, when Olin must a submit a cleanup feasibility report, detailing the technological and financial constraints on cleaning the groundwater. Current technology can detect perchlorate below 1 part per billion and clean water to non-detect levels.
“At this point the strongest argument for proposing something higher than non-detect would be economics,” Hernandez said. “They have to follow the clean up process of the water code. They can propose whatever they want, but until they go through the process, we won’t accept it.”
