Denver-based CH2M Hill said it will set up its portable "Controlled Detonation Chamber" technology at Schofield, provide technical support during operations, and disassemble and remove the system once the project is completed.

In early 2006, the Army said it destroyed six rounds containing chloropicrin, an asphyxiator used in World War I. Army officials said 152 rounds with chloropicrin and phosgene, another choking agent, were discovered during the cleanup of an old range that was to be used for the Stryker brigade.

The reason for the old weapons' presence was a mystery, but Kendrick Washington, a spokesman at the time, said, "We suspect that these rounds were used for military training or quality control testing during World War II.

Schofield officials could not immediately be reached for comment this morning.

The unexploded ordnance cleanup also yielded other potentially dangerous surprises for the Army, including depleted uranium used in aiming rounds from a 1960s nuclear weapon system called the Davy Crockett.

CH2M Hill said its system is the only transportable detonation chamber approved by the Defense Department's Explosives Safety Board for the destruction of munitions, including those labeled "Munitions and Explosives of Concern."

The company said more than 1,500 sites across the United States, encompassing an estimated 15 million acres, may contain such munitions, and growing concern about traditional open-burn and open-detonation destruction led to the "environmentally friendly" detonation chamber system.

Initial X-rays of some of the old chemical weapons found at Schofield showed they were filled with liquid and had unstable fuses that made some unsafe to move.

Experts from the 22nd Chemical Battalion's Technical Escort Unit made the identification using a portable isotopic neutron spectroscopy system that used gamma rays to identify a chemical signature.

The unit's early assessment found 4.2-inch mortars; 155 mm projectiles; 81 mm mortars; 75 mm projectiles; 4-inch Stokes mortars; a Livens Projector; and a 105 mm projectile.

The Army in August confirmed that depleted uranium from the Davy Crockett weapons system was found at Pohakuloa Training Area on the Big Island.

How much of the material was detected still is unclear. The Army said initial testing was done to determine the presence of depleted uranium, or DU, not the quantity of it. There is no public access to the area where the heavy metal was found.

In January 2006, the Army said it had found 15 projectile tailfin assemblies that contained depleted uranium at the Schofield Barracks munitions impact range.

The depleted uranium was used in XM-101 aiming rounds that simulated the trajectory of the Davy Crockett, a formerly classified recoilless rifle that could fire a 76-pound nuclear bomb.

The Army said the DU at Pohakuloa Training Area is the same type of material found at Schofield.

Earlier this summer, the Army said it had found more depleted uranium fragments at Schofield, and that the aiming rounds also may have been fired at Makua Valley and Pohakuloa.

Contractor Cabrera Services conducted an aerial survey of the impact area at Pohakuloa as part of the Army's efforts to determine the extent of DU use in Hawai'i and the best way to remove or mitigate it.

The Army also previously said it was unaware of the presence of the weakly radioactive element until a contractor removing unexploded ordnance for the Stryker brigade discovered it in 2005 at Schofield.