WITHIN FIVE years, the lethal stockpile of 50-year-old chemical weapons stored at Aberdeen Proving Ground will be dissolved -- with a strong dose of hot water and sewage sludge.

This month the federal Environmental Protection Agency approved plans to build a $306 million complex of buildings on the sprawling Army installation in Harford County, where 1,800 steel canisters of blistering mustard agent would be neutralized by 2004.

EPA approval was essential to proceed with this method of disposing of the chemical warfare elements. Stockpiles meant for World War II use languished at APG and seven other U.S. sites.

Heat and microbial treatment to destroy the stockpiles was proposed for years, backed by scientific studies. But the Army clung to incineration of all chemical weapons, despite community protests, after Congress ordered their disposal. In 1997, the Defense Department finally approved the water neutralization alternative for APG.

The process involves thorough mixing of the syrupy mustard agent in near-boiling water and adding sodium hydroxide (a caustic used in making paper and soap). The resulting solution is treated with bacteria from sewage plant sludge, and the liquid waste is piped to a conventional wastewater treatment plant.

Disposal methods at other chemical-weapon sites will vary. Incineration is used at two sites, and an Indiana arsenal will use a variation of the APG system to neutralize nerve gas. All 30,000 tons of U.S. chemical weapons are to be destroyed by 2007, under international treaty.

The federal (and state) permits for APG allow construction to begin next month on the neutralization facilities.

It's a welcome move that will lift a long-standing cloud of worry from the region.

Pub Date: 3/16/99