Rocketdyne Denies Fouling Nearby Wells

Finding themselves on the defensive after investigators discovered a highly toxic chemical in Simi Valley and at Ahmanson Ranch, officials with defense contractor Rocketdyne said Thursday that their test site in the Santa Susana Mountains is not responsible.

During a media briefing at the Santa Susana Field Laboratory -- a nuclear testing ground in the 1950s -- Rocketdyne scientists said years of research into the soil, water and geology of the hilltop site between Simi Valley and Chatsworth show that the chemical perchlorate could not have traveled to the valley floor.

Their statement came in response to the discovery by state investigators of the chemical in 18 shallow wells scattered across Simi Valley. Perchlorate, a component of rocket fuel, can cause thyroid dysfunction in humans.

None of the affected monitoring wells provides drinking water to valley residents.

“Scientifically, you would see some type of a trace or fingerprint, and it’s just not there,” said engineer Richard Andrachek, who works with Rocketdyne scientists to measure and monitor contamination at the 2,800-acre site.

The highest concentration found in Simi Valley was 20 parts per billion. Any level above 4 parts per billion is considered dangerous.

The recent discovery by state investigators coincides with a finding of trace amounts of perchlorate in a well at nearby Ahmanson Ranch.

Although there are several “hot spots” of perchlorate contamination in the soil and water at the field lab, data do not support critics’ theory that perchlorate passed from the site to the valley via streams and springs, Rocketdyne officials said.

Experts with the state Department of Toxic Substances Control, which performed the Simi Valley studies, agree that the evidence does not point to Rocketdyne.

If the chemical had come from the Santa Susana site, trace amounts would have been found in the soil and bedrock surrounding the lab, said Gerard Abrams, a state geologist who oversaw the well studies.

“We weren’t able to find any connection to the activities at Rocketdyne,” Abrams said Wednesday night during a public meeting in Simi Valley to discuss contamination cleanup at the site. “If surface release was the source of contamination, there would have to have been an awful lot of perchlorate that moved down the drainage, and it’s not there today. I don’t see how that can be.”

Geological maps of the area show there is no direct drainage system to the Ahmanson well, which is three miles from the nearest Santa Susana well known to contain perchlorate.

However, Ali Tabidian, a professor of hydrogeology at Cal State Northridge who has studied the area for more than a decade, theorizes that the substance was carried down the mountain from Rocketdyne by water trickling through natural drainage systems.

He presented his theory at the meeting Wednesday night, ending his remarks by saying, “Based on the data, there is no reason to believe the source is anywhere but the Santa Susana Field Laboratory.”

Rocketdyne officials suggest a former plant nursery on Ahmanson Ranch may have been the source of the perchlorate there. The chemical is an ingredient of a fertilizer imported from Chile that may have been used at the nursery, they said.