CAMU begins on-site treatment of soil from Labs’ Cold War-era Chemical Waste Landfill

When the front-end loader last week thudded its first load — the very first load — of soil from the Chemical Waste Landfill into the hopper of the low temperature thermal desorption (LTTD) soil treatment unit, members of Sandia’s Corrective Action Management Unit (CAMU) team didn’t so much as exchange high-fives.

Instead, assistant CAMU task leader Bob Helgesen (6134) simply nodded across the way to the action at the treatment unit and said, almost casually, "That’s a historic moment there. It took a lot of years to turn that [LTTD unit] on."

The LTTD unit, brought on site and operated for the CAMU by URS Group Inc., heats contaminated soil to from 400 to 700 degrees F to cook off volatile organic compounds. The special machine, the size of a couple of Peterbuilts with their reefers on, captures the resulting particulates and scrubs and neutralizes (through a catalytic process) the acidic gases produced. The final emission coming out of the unit’s exhaust stack contains water vapor, CO2, and CO. The LTTD can handle some 10 tons of contaminated soil per hour. At that rate, says CAMU task lead Mike Irwin (6134), it’ll likely be operating on site 20 hours a day for the next three to six months treating soil from the Chemical Waste Landfill.

Sandia’s Chemical Waste Landfill, tucked away on a bit less than 2 acres in the far southeast corner of Tech Area 3, was the repository of chemical wastes from 1962 till 1985. In the midst of waging the Cold War, Sandia’s — indeed, the nation’s — attention was focused not so much on environmental concerns as on countering the Soviet nuclear threat. As such, sites like the Chemical Waste Landfill weren’t designed or operated with the same level of care for the environment that would apply today. The chemical residue of Sandia’s weapons work went into the landfill. Now, some 9,000 cubic yards of bulk soil from the landfill will be treated with the LTTD unit. An additional 24,000+ yards of soil, contaminated with metals, will be treated via soil stabilization. Among organic compounds in the soil are:

• 1,1,1-trichloroethane, a solvent used for degreasing electronic equipment.
• Aniline, a chemical used in making resins, dyes, and varnishes.
• Bis(2-ethelhexyl)phthalate, a plasticizer for resins.
• Acetone, another solvent for resins, and a degreaser.
• Polychlorinated biphenyls, or PCBs, were banned by the Environmental Protection Agency for most applications in 1979. They were used as plasticizers and as an insulating medium and coolant for large electrical equipment.

In 1989, as the urgencies and expediencies of the Cold War began to be looked at in a different light, attention turned to environmental restoration. Along with several other sites — the Mixed Waste landfill, the Classified Waste landfill, and others, the Chemical Waste Landfill was identified early on for remediation. After initial soil sampling, it was estimated that to excavate the Chemical Waste Landfill and move the contaminated soil — some 37,000 cubic yards of it (that’s enough dirt to bury a football field 30 or so feet deep) — would cost in the neighborhood of $280 million. That cost seemed prohibitively expensive, even for as worthy a task as environmental restoration.

Fortunately, at the time these decisions were being made, the US EPA had approved the establishment of an on-site waste management approach — the CAMU. The CAMU option, which turned out to be perfectly appropriate for Sandia’s Chemical Waste Landfill, will have an estimated lifetime cost of $30 million (the lifetime cost is based on 30 years of EPA-mandated oversight of the CAMU facility).

A series of public hearings about the proposed CAMU has indicated strong public support, David says. "They’re very much behind us on this."

Mike, who assumed the role of task leader after previous leader Scott Schrader passed away after a long bout with cancer (Lab News, Aug. 11, 2000), says the latest CAMU milestone is the culmination of "a lot of work by a lot of people over the past few years."

Despite the palpable sense of accomplishment and satisfaction among the CAMU team as the switch on the LTTD unit is thrown in earnest for the first time, Mike says there won’t be a team celebration just yet.

"We’ve still got a lot of work to do," he says.