Mark W. Salley
Communications Director
Colorado Department of Public Health and Environment
303-692-2013

Gary Sky
Communications
Tri-County Health Department
303-846-6245

Warren Smith
Community Involvement Manager
Colorado Department of Public Health and Environment
Hazardous Materials and Waste Management Division
303-692-3373

DENVER - The Colorado Department of Public Health and Environment, U.S. Environmental Protection Agency and Tri-County Health Department today approved the Rocky Mountain Arsenal’s work plan to investigate the source of lewisite, a chemical weapon detected Oct. 31 while Army contractors were excavating a trench at the site. Contractors were digging in an area known as the Lime Basins, which were used to treat liquid waste from past lewisite production.

Lewisite is a liquid chemical compound developed by the United States during World War I for use as a poisonous gas. Like mustard gas, lewisite is a blistering agent. Lewisite penetrates ordinary clothing and even rubber, and its absorption through the skin may be fatal. When inhaled, it is a powerful respiratory irritant. Inhalation causes a burning pain, sneezing, coughing, vomiting and possibly swelling in the lungs. It was manufactured at the Arsenal for eight months in 1943.

Tomorrow, technical experts will begin sampling and visually inspecting the soil that was excavated from the trench at the time the lewisite detection occurred. While conducting the investigation, Army contractors wearing protective safety equipment will spray a caustic bleach solution on the soil to suppress dust and neutralize any residual lewisite that may remain. This process is expected to take approximately four days. Air monitoring will continue at the work site throughout the investigation.

The goal is to better identify whether the lewisite detected in the air was the result of leakage from buried lewisite in a container or in the soil from historical liquid disposal practices from the 1940s. The results of the investigation will determine future clean up processes on the excavated soils and completion of the trenching.

The Lime Basins project is located in a restricted area of the arsenal within the central portion of the site. The trench was being excavated around the perimeter of the Lime Basins to prepare for the installation of a 45-foot underground vertical barrier wall and a future cover over the site. The barrier wall and cover are designed to prevent future contamination of groundwater. Since the initial detection, air sampling at the project site has continued to show no new detectable lewisite.

The U.S. Fish and Wildlife Service has decided to keep the Rocky Mountain Arsenal National Wildlife Refuge closed for now as a precautionary measure and will reopen when all the organizations agree that it is safe.

Community members with questions about the ongoing cleanup of the arsenal are encouraged to contact the site’s Community Information Line at 303-289-0136 or the Tri-County Health Department’s Rocky Mountain Arsenal Information Line at 303-286-8032.