COMMERCE CITY, CO – On Oct. 31 cleanup experts at the Rocky Mountain Arsenal (Arsenal) confirmed the presence of Lewisite through air monitoring results while working on the Lime Basins cleanup project.  As soon as the Lewisite was detected, work on the project and visitation to the Rocky Mountain Arsenal National Wildlife Refuge was immediately suspended.  The Lime Basins project is located in a restricted area within the central portion of the site.

The cleanup project involves digging a trench around the perimeter of the Lime Basins to prepare for the installation of a 45-foot vertical barrier wall and a future cover over the site.  Air monitoring at the trench excavation area confirmed Lewisite, however, the project’s perimeter air monitoring samples continue to be negative.  Crews are approximately 75 percent complete with the trench excavation around the perimeter of the five-acre site.

A work plan is being developed to further investigate the source of the Lewisite detection and will be coordinated with and approved by the regulatory agencies.  In the meantime, the Lime Basins project and visitation to the Refuge is suspended.  The top priority continues to be the safety of our workers and the surrounding communities.

Originally constructed in 1942, the Lime Basins were designed to receive wastewater from the production of Lewisite.  Lewisite is a type of chemical warfare agent and was produced at the Arsenal from April 1943 to November 1943.  The wastewater was treated with lime, which acted as a neutralizer, and also removed arsenic.  Due to the history and former use of the site, experts working on the cleanup project were appropriately trained, prepared and were wearing protective gear including Tyvek suits, respirators and supplied air in case Lewisite or other chemicals were detected.  Air monitoring continues around the project’s perimeter with samples taken every three hours.  The project site remains secured and regulatory officials have been notified.

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.  Information is also available at www.rma.army.mil.

Site History

Currently, the Rocky Mountain Arsenal is more than 75 percent complete with its ongoing, extensive environmental cleanup of the site’s soil, structures and groundwater. Cleanup plans were developed and approved by the U.S. Army, state of Colorado, U.S. Environmental Protection Agency, Shell Oil Co., Tri-County Health Department and U.S. Fish and Wildlife Service.  

Once the remainder of the cleanup is complete, the Arsenal’s vast open spaces will constitute one of the nation’s largest urban wildlife refuges.  By fall 2006, more than 12,000 acres of Arsenal land had been transferred from the U.S. Army to the U.S. Fish and Wildlife Service, officially establishing and later expanding the Rocky Mountain Arsenal National Wildlife Refuge.  After the Arsenal’s remaining cleanup projects are completed and removed from the EPA’s National Priorities List, the Army will transfer about 2,500 acres to the Service to further expand the Refuge.  By 2011, the cleanup program will be finished and the Army will retain approximately 1,100 acres to maintain its landfills and groundwater treatment plants. 

The Refuge now provides environmental education programs, close to 10 miles of trails, wildlife viewing opportunities and site tours for the public, and a sanctuary for more than 330 species of animals, including wild bison, deer, coyotes, bald eagles and burrowing owls.

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