A $7 million testing program to find the cheapest and safest way to destroy hundreds of thousands of tons of obsolete munitions is under way at the Army's Dugway Proving Ground.

Open burning and open detonation are the least expensive and most efficient methods of disposing of old munitions, according to the Army.But to get burn permits from the Environmental Protection Agency and state regulatory agencies, the military must supply documented proof that such operations will not pollute the environment.

The Dugway research program, which includes disposal of small amounts of old munitions, started in 1986 and will go on for some three years, said Army project manager MacDonald Johnson.

"What the EPA is asking for is a data base that conclusively and scientifically shows there will be no impact on the environment," he said. "We've been trying since 1986 to get to a point where we can say, `This is what will happen if you destroy this type of munition by this method.' "

Dugway was chosen as the test site because of its expertise, data-gathering equipment and remote location in Utah's western desert. It is one of the few testing facilities with ready access to a sophisticated instrument that reads particulate concentrations in parts per billion.

"It's been difficult to trace levels of parts per billion in open burn and detonation situations," Johnson said.

To visualize the tiny amount of parts per billion, he said, equate one second to 31,500 years in time.

Johnson said a testing methodology involving a sampling platform in an aircraft, instrumentation and an analytical system for accurate analysis in the air and soil had been developed, but not a database that will enable the military to specify what can and can't be done when applying for permits.

The United States is not the only country with a munitions disposal problem, according to the Army.

Recently, representatives from the German Ministry of Defense came to Dugway to observe testing. Germany has some 300,000 tons of munitions, some dating back to World War I.

The last test in Phase C was completed at Dugway on Sept. 18 when four common munitions were detonated. Phase A tests were completed in June 1989 and Phase B ended Nov. 1, 1989.

Workers also have monitored open burning of propellants in 24 burns ranging in size from 5,000 to 7,200 pounds each.

The solid propellants are the types most common in both the Army and Navy inventories and were burned in large metal trays to protect soil and achieve accurate results. The tests are coordinated with EPA and local officials, according to the Army.