Tooele Army Depot, Utah — A small cluster of ammunition ``igloos'' on this isolated western Army base symbolize what might be the toughest toxic waste disposal problem in the world. Huddled alone on a valley floor, the igloos contain 42 percent of the US stockpile of obsolete chemical weapons. Behind their concrete doors are shells, rockets, and spray tanks filled with lethal nerve agent or skin-blistering mustard gas - all judged unusable, some leaking.
The Army, prodded by Congress, has long struggled with the issue of how best to get rid of this deadly junk. After years of controversy, the plan now is to burn the weapons on-site here, at seven other smaller storage sites in the US, and at a Pentagon facility on Johnston Island in the Pacific Ocean.
``Nerve agent burns very well,'' said depot head of chemical destruction Stew Paulick during a tour of Tooele earlier this year. ``One type has half the heating value of No. 2 fuel oil.''
A pilot incinerator plant which resembles an insecticide factory has already been built here at Tooele. Inside, machinery drains munitions of their poisons, chops up and scorches metal carcasses, and pumps the chemicals to a central ``clean room.'' A small gray furnace then reduces the nerve agent and mustard to ash.
Tooele officials stress that their operations are safe. Workers near the furnace, for instance, are heat-sealed in large plastic suits. But accidents have happened. The Tooele pilot plant was shut down for most of 1987, after a pipe leaked in the furnace room, and a trace of nerve agent escaped to the outside atmosphere.
Congress originally set a 1994 deadline for destruction of the obsolete chemical weapon stockpile. But wrangling over destruction methods, plus funding cuts and technical changes, now mean the Army won't be done until 1997 at the earliest.
Public opposition to incineration at chemical dumps in relatively densely populated areas, such as the Lexington-Blue Grass Army Depot in Kentucky, was strong.
``They just wanted them moved and destroyed somewhere else,'' says Brig. Gen. David Nydam, Army program manager for chemical demilitarization.
There is no ``ideal answer'' for what to do with these weapons, says Robert Buchheim, a former arms control official who headed a National Research Council panel which analyzed the issue in 1984.
Ocean dumping, once the preferred method of disposal in the US and Western Europe, is now considered environmentally unacceptable. High-temperature incinerators are seen as the only viable option.
Britain and West Germany already have special facilities for burning old chemical munitions, but on a much smaller scale than the network slated to be built in the US.
Construction on a full-scale disposal plant at Tooele is scheduled for 1989. Ground for similar facilities will be broken in 1991 at Anniston Army Depot in Alabama, Pine Bluff Arsenal in Arkansas, and Umatilla Army Depot in Oregon.
Work will begin in 1992 at Aberdeen Proving Ground, Md; Lexington-Blue Grass Depot, Ky; Newport Army Ammunition Plant, Ind.; and Pueblo Army Depot, Colo.
In some ways US Army chemical officers should count themselves fortunate: In Europe, disposal teams are still digging up unexploded chemical munitions left over from previous wars.
The West Germans, who no longer produce or stockpile such weapons, have to X-ray vintage bombs in order to figure out the safest way to cut open and destroy the rusty hulks.