Half a century after America's first partial nuclear meltdown, hundreds of radioactive hot spots remain at a former research facility overlooking the west San Fernando Valley, according to a recently released federal study.
The U.S. Environmental Protection Agency's $41-million survey of the facility, now owned by Boeing Co. and NASA, is expected to provide a precise map for state and federal agencies hoping to clean up the site by 2017.
It also sets the stage for determining a final disposition for the 2,850-acre site, which is home to rare plants, great horned owls and four-point bucks.
That won't be easy. Environmentalists and Boeing officials are already clashing over plans to transform the site near the Santa Susana Mountains into public open space.
Boeing spokeswoman Kamara Sams said her company wants to donate the property for use as "open space parkland" available to nature enthusiasts, hikers, bikers, rock climbers and nonprofits such as the Girl Scouts.
Environmentalists, however, are insisting that it first be designated for "unrestricted suburban residential uses," which are held to stricter pollution standards.
"Everyone can agree that it would be lovely for that area to be open space," said Daniel Hirsch, president of the antinuclear group Committee to Bridge the Gap. "But we want to make sure it is fully cleaned up before that happens."
Once home to 10 nuclear reactors and plutonium- and uranium-carbide fabrication plants, the facility also hosted more than 30,000 rocket engine tests as the nearby San Fernando and Simi valleys were experiencing a postwar population boom.
The EPA survey, three years in the making, collected 3,735 soil and sediment samples and 215 groundwater and surface water samples. Each sample was analyzed for 54 radioactive contaminants.
The EPA says 423 of the samples contained man-made radioactive contaminants exceeding background levels. Most of the contaminants were cesium-137 and strontium-90, both powerful carcinogenic substances.
Most samples exceeding background levels were found in the surface soil at locations known to be contaminated, including where the partial meltdown occurred on the morning of July 14, 1959. Details of that incident, which spewed colorless and odorless gases into the atmosphere, were not disclosed until 1979, when a group of UCLA students discovered documents and photographs that referred to a problem at the site involving a "melted blob."
Boeing said in a statement that the EPA survey "overwhelmingly revealed no surprises or health hazards to our employees, neighbors or people in the community."
William Preston Bowling, founder of the Aerospace Contamination Museum of Education in Chatsworth, disagreed.
"The good news is we now know how bad things are on the site," Bowling said. The bad news is that the high levels of contaminants were in an area that drains into the headwaters of the Los Angeles River, he said.
A year ago, Boeing prevailed in a lawsuit filed in U.S. District Court to overturn a 2007 state law that created stricter cleanup standards for the facility. A federal judge ruled that the cleanup of the site should be not treated differently from the cleanup of other polluted areas in California.
The plan is to eliminate man-made radioactive materials within five years. But it may take decades longer to remove trichloroethylene, a chemical that is used to wash rocket motors, from the local aquifer, Boeing spokeswoman Sams said.