The Edgewood Chemical Activity (abbreviated ECA) was a U.S. military site located in Maryland that stored chemical weapons. Since 1941, the U.S. Army stored approximately five percent of the nation's original chemical agent in steel ton containers, at the Edgewood Area of Aberdeen Proving Ground. Construction of the Aberdeen Chemical Agent Disposal Facility was completed in 2002, and agent destruction operations began in April 2003. Destruction was completed in February 2006, with 1,622 tons (1,472 metric tons) of agent destroyed. This facility used neutralization followed by bio-treatment to destroy mustard gas agent (HD) drained from ton containers. As of 2006, ABCDF personnel are currently working to safely close the facility.