Toxin Detected in Simi Ground Water

State investigators have found a highly toxic chemical used in rocket fuel in 18 water wells in Simi Valley, but the contamination has not been traced to the nearby Rocketdyne testing site.

The chemical perchlorate, which has been linked to thyroid problems, has also been found in wells at the Santa Susana Field Lab, but there is no evidence that contamination in the city migrated from there, according to a new report by the state Department of Toxic Substances Control.

Drinking water supplies are not contaminated or threatened, officials said, because most of Simi Valley’s tap water is imported from Northern California.

With the latest findings, perchlorate has now been detected in ground water at three locations on the Rocketdyne site, and in lower concentrations in wells to the north, south and east of the hilltop lab.

The highest state reading was 19.2 parts per billion -- nearly five times the allowable limit of 4 ppb -- at a monitoring well at a gas station in Simi Valley. The readings were taken earlier this year.

State investigators could not determine the chemical’s source, but they noted that Rocketdyne is the nearest known location with perchlorate contamination. Solid rocket fuel “is the main source of perchlorate contamination found in ground water” across the nation, they said.

Rocketdyne officials said there is no proof the chemical comes from the lab, noting that perchlorate has not been detected in springs in the undeveloped area around the site.

“The data from the state is very compelling and shows it’s not coming from Rocketdyne,” said Art Lenox, an environmental scientist at the lab. “But activists continue to want to use the data to point fingers at Rocketdyne.”

The company has tested wells of various depths around the lab’s perimeter, and no seepage was detected, Lenox said.

The perchlorate discovered in Simi Valley more likely came from firecrackers, fertilizer or road flares, all of which contain the chemical in concentrations high enough to trigger the findings, he said.

The geology of the field lab, with its bedrock faults and sandstone, would absorb contaminants and minimize migration, Lenox said. What’s more, he said, a large part of the work conducted at Santa Susana involved kerosene or liquid oxygen, not heavy rocket fuel containing perchlorate.

The closest structure on the lab site is about a mile south of Simi Valley city limits and about 1 1/2 miles from the nearest housing subdivision. Several contaminated wells are within 2 1/2 miles of the closest building at the rocket-testing site.

From January to August, state officials took water or soil samples from 76 wells -- 68 shallow and eight deep -- 25 springs and 30 drainage ditches between Rocketdyne and Simi Valley.

The state detected perchlorate in ground water less than 20 feet below the surface in wells north of the field lab. Perchlorate also was found this year south of the lab, near the proposed Ahmanson Ranch housing development, and it was detected in a well east of the site last year.

Activists said they are concerned not only about perchlorate but other chemicals that may be migrating behind it. Perchlorate tends to lead contaminant plumes.

“There was a large amount of perchlorate usage [at the lab], with heavy contamination,” said environmental activist Dan Hirsch. “It’s the only known perchlorate source nearby. Where else could the stuff have been coming from?”

Assistant City Manager Laura Magelnicki said that although the findings pose no immediate health concern, residents and city officials want to know the source of the toxic chemical.

“If these results don’t give us any definitive answers, then we’ll continue to work with the state about doing further analysis to get an answer,” she said.

State officials will discuss their findings during a meeting Wednesday in Simi Valley sponsored by the federal Environmental Protection Agency. It will be held from 6:30 p.m. to 10 p.m. at the Grand Vista Hotel, 999 Enchanted Way.

Rocketdyne, a division of Boeing, conducted nuclear energy research at the lab for decades until chemical and nuclear contamination was found in 1989. The lab is now undergoing a federally funded $186-million cleanup, but rocket testing continues at the site.