The 6,000-acre F.E. Warren Air Force Base site is located in Laramie County, immediately west of Cheyenne. Historically, the base has served as a cavalry outpost, quartermaster depot and intercontinental ballistic missile operations base. Past operations and disposal practices contaminated soil and groundwater with hazardous chemicals on base and at some adjacent private residences. Cleanup is complete at many areas. Operation and maintenance activities and monitoring are ongoing at these areas. Investigation and cleanup activities continue at the remaining areas.