2011-09-08 / Front Page

Ground water investigation plods along

By Carissa Marsh

Contaminated soil is not the only concern at the Santa Susana Field Lab.

The groundwater that flows beneath the 2,850-acre sandstone mountain, a former rocket engine testing and nuclear research facility, is also tainted.

Just how tainted is a question yet to be answered.

The agencies responsible for the cleanup of the testing site just north of Oak Park have been investigating the contamination since the late 1980s but the Department of Toxic Substances Control (DTSC), the state agency overseeing the cleanup, says more work needs to be done before remediation can begin.

“It’s in the most complicated hydrogeologic environment. . . . They used chemicals out there and did processes out there that just aren’t done anywhere else,” said Tom Seckington, senior engineering geologist for DTSC. “You add that all together and that makes this a very complicated site. It’s a tough nut to crack.”

On Aug. 11 at Simi Valley City Hall, representatives from the DTSC presented a Sitewide Groundwater Remedial Investigation Report.

“We want to fully characterize the nature and extent of the contaminants,” Seckington told the audience, mostly locals who’ve been engaged in the cleanup process for years.

“Characterizing the nature” means determining what kind of contaminants are on the site, where they were released and at what volumes. Also being studied is how far and how deep the contaminants have traveled.

Figuring it all out is like solving a puzzle: DTSC must find the missing pieces to get a clear, complete picture of the site.

Though there is disagreement between DTSC and the responsible parties— Boeing, NASA and the Department of Energy—about how much of that puzzle is still missing, Seckington said all sides agree additional investigation is necessary to find out where the contaminants still exist and where they are moving.

The report details recent investigation activities, such as the sampling of wells and the study of seeps, maps and deep corings.

In addition, the report examines the geology and hydrogeology of the site, the persistence of chemicals and other contaminants in the bedrock and groundwater, and the impact of the groundwater on nearby people and animals.

DTSC must approve the final investigative report before corrective measures can be taken.

Residents at the Simi meeting expressed concern over the amount of work that still needs to be done.

“How much more is going to be needed? Are we talking months, years?” asked San Fernando Valley resident Mark Osokow.

Seckington said his time line allows until 2014 to complete the site characterization.

“It’s hard for me to say how much more. I can say this, they’ve done a lot,” he said. “Before, in the 1980s, 1990s, we didn’t know what we didn’t know about this site. At least now we know what we don’t know, so we can move forward.”

“It’s not going to take another 24 years,” he said.

Others had questions about the methods that would be used in the cleanup.

It is thought that nearly all of the contaminants lie in a relatively safe rock matrix underneath the site.

But Santa Susana Knolls resident Marie Mason disagrees with and worries that the toxic chemicals won’t be fully treated and removed, and could still cause harm.

“If the contamination is coming off the seeps and springs, then it is not being held in the rock,” she said. “Living below (the site) with creeks running through my yard . . . I think we need to be sure,” Mason said.

DTSC representatives said further study will help identify which corrective measures are necessary.

“ We need to get enough information to do an assessment of what technologies will approach the cleanup and be most effective in the cleanup,” said Mark Malinowski, DTSC project manager.

Still others were worried that there are offsite data gaps—in particular, that contamination plumes have migrated to the long-dry Chatsworth Reservoir. They said testing should be done to rule out risk to the surrounding community.

But Seckington said the fears are “unlikely” since plumes tend to dwindle as they move out and that if contaminants were moving off site in large concentrations, that trail would be seen in the network of monitoring wells.

“I can’t say there’s no possibility of anything going off site. Our uncertainty is too high because we don’t have enough information yet,” he said. “But saying that, do I think anything is rushing off site? We don’t have any data to support that.”

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