The Army has destroyed 89 percent of the chemical warfare agents formerly stored at the Deseret Chemical Depot near Tooele. But hundreds of thousands of old mortar rounds and other garbage fill dumps on the base, some of them conventional weapons, some of them chemical. Until this Cold War refuse is properly disposed, unacceptable environmental and safety hazards will remain.

The Army's accomplishments at its Tooele Chemical Agent Disposal Facility should not be demeaned. A sophisticated incinerator has burned up much of the nation's chemical warfare arsenal under provisions of an international treaty. That good work has made life safer for all Utahns.

But the cleanup work on the base will not be done until the so-called "nonstockpile" munitions, which do not at present fall within the inventories covered by the chemical weapons treaty, are also properly disposed. These weapons were buried or tossed into surface dumps and are so corroded or damaged (some were burned) that they cannot be used in combat. But some still contain explosives or residual chemical agents or both. The old weapons were tossed aside between 1945 and 1978.

Trouble is, they still pose the hazard of explosion or groundwater contamination. No one knows exactly how many there are, because they have never been properly inventoried. What is known is that there are 48 identified burial sites in Utah.

Another problem is that they may pose a greater risk to human life by trying to dig them up than by leaving them alone. That's part of why the Army hasn't been more aggressive in cleaning up its mess. Plus, if chemical weapons agents are discovered among the debris, they then must be declared as part of the nonstockpile munitions under the treaty and properly destroyed.

The Army has talked about someday using robots to excavate and explore the old weapons garbage, but so far that's mostly just talk. It would be expensive, of course.

But the Army can't be allowed to walk away from the problem. Monitoring wells below some of the dumps reportedly show that water is not flowing toward Tooele or the Wasatch Front. However, the studies arising from the controversy about groundwater below Snake Valley have shown that aquifers below the Great Salt Lake Basin are remarkably interconnected.

Utahns don't want to get an ugly chemical surprise someday.