Capping McClellan toxics safe, military says

As it promotes a proposal to cap, rather than remove, long-lived radioactive waste at the former McClellan base, the Air Force is issuing assurances that well-maintained seals can hold for thousands of years.

To prevent human contact with the waste, generations of caretakers would have to routinely maintain and periodically rebuild the barriers.

"It's a legacy," said Steve Mayer, who heads the Air Force cleanup. "This remedy is something that will have to be maintained in perpetuity."

The proposal must be approved by the U.S. Environmental Protection Agency.

Air Force officials say they are confident the caps will work and allow for some commercial development at the old waste dumps.

They point to one such cap site, constructed 22 years ago, that covers a series of unlined industrial waste trenches at the northwest corner of McClellan. Wells puncture the cap, extracting toxic vapors from the soil and contaminated groundwater 100 feet below. Yet the barrier has held firm.

"It's been trouble-free," Mayer said. "This has been a good test bed for us."

Still, state health officials wonder whether the barriers can stand the test of centuries.

The pits likely contain long-lived radioisotopes, predominantly radium-226 from luminescent aircraft instruments. McClellan was a major aircraft repair depot and supply base from 1936 through June 2001.

Radium-226 has a half-life of 1,600 years, the time it takes the substance to lose 50 percent of its radioactivity by decay. Plutonium-239, found in one unearthed drum at McClellan, has a half-life of about 24,000 years.

"We don't want someone doing some plumbing or boring in the future to hit bottles of plutonium left here," said Robin Hook, environmental management chief for the state Department of Public Health.

"We don't know whether this is a safe plan until the Air Force gives us a better characterization of what's in those pits," Hook said. "We're still waiting."

Air Force officials say probing the pits could expose excavation workers to hazardous substances and that they believe they already have a good indication of what the pits contain.

Interviews with former McClellan workers and documents of historic base operations have given cleanup managers "a good understanding of what could be in those pits," said Dave Green, radiation safety officer for the Air Force Real Property Agency at McClellan.

At the same time, the agency states in its capping proposal, "There is significant uncertainty on the type and levels of radioactive wastes that may be present in the pits."

That uncertainty gives county redevelopment officials pause.

That's because the Air Force is looking to transfer ownership and cleanup responsibility of the 3,000-acre complex in North Highlands.

On Aug. 27, Gov. Arnold Schwarzenegger and federal environmental officials are scheduled to sign an $11.2 million deal approving the first property transfer: a 62-acre parcel to McClellan Park, the commercial redeveloper at the former base.

The privatization agreement is designed to hasten cleanup and redevelopment. It also may become a template for additional transfers of contaminated lands at McClellan and former military installations across the nation.

The inaugural transfer does not include the sites with radioactive waste proposed for capping, but does contain soil tainted with polychlorinated biphenyls, used as coolants and lubricants.

Federal law requires the Air Force to evaluate the integrity of the barriers every five years, even if the property later changes hands, Mayer said.

"If there is any problem developing, that would be turned back on to the Air Force to correct it," Mayer said. "It's obviously in the best interest of the Air Force to put in the most durable and long-lived technology we can."

Some Sacramento County officials remain unconvinced.

Supervisor Roger Dickinson, whose district includes McClellan, said the opportunity to develop some areas into office buildings might be jeopardized by leaving toxic waste in place. McClellan Park has 170 business tenants with about 13,000 employees.

About the writer:

• The Bee's Chris Bowman can be reached at (916) 321-1069 or cbowman@sacbee.com.