250 Buried Chemical Weapons Sites Across 40 U.S. States Remain Uncleared

The U.S. Department of Defense has identified approximately 250 sites across 40 states, the District of Columbia, and three territories where chemical warfare materiel remains buried underground from World War I and II-era production, testing, and disposal. These are not remote military ranges -- many sit beneath residential neighborhoods, university campuses, and commercial developments that were built decades after burial without anyone knowing what was underneath. The Spring Valley neighborhood in Washington, D.C. is the most vivid example of why this matters. The U.S. Army used American University as a chemical weapons experiment station during World War I, and when the station closed, leftover munitions and chemicals were buried in what was then rural farmland. Homes were built on top. When the contamination was discovered in 1993, excavators found over 2,000 pounds of laboratory debris, 53 glass containers still filled with chemical agents, 7,500 tons of contaminated soil, and more than 550 munitions beneath a single property. The cleanup took over two decades and cost approximately $270 million. Meanwhile, residents lived next to active excavation of mustard gas shells. The Redstone Arsenal in Alabama alone is estimated to contain 20,000 to 25,000 buried chemical weapons that are relatively stable in the ground but volatile once disturbed -- meaning every construction project in the area is a potential trigger. This problem persists because the original burial records are incomplete or lost. The military buried weapons hastily during wartime using methods that seemed adequate in the 1910s-1940s: open pits, shallow trenches, backfilled with dirt and forgotten. Decades of land-use changes, property transfers, and urban expansion erased institutional memory. The Army Corps of Engineers lacks funding to systematically survey all 250 sites, so most are discovered reactively -- during construction, flooding, or property transactions -- rather than proactively. Each discovery triggers a multi-year, multi-million-dollar remediation that disrupts communities and craters property values, but there is no national program to get ahead of the problem.