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Record of Decision System (RODS)



City & State:  CHEYENNE  WY  82005
County:  LARAMIE
EPA ID:  WY5571924179
EPA Region:  08
NPL Status:  Currently on the Final NPL
ROD Type:  Record of Decision
ROD ID:  EPA/541/R-98/508
ROD Date:  11/21/1997
Operable Unit(s):  08
Media:  Groundwater
Contaminant:  VOCs, trichloroethylene
Abstract:  F.E. Warren Air Force Base occupies approximately 5,866 acres immediately adjacent to the west side of the City of Cheyenne, Wyoming. Historically, the base has served a number of military functions including cavalry outpost, quartermaster depot, and intercontinental ballistic missile operations base. Operations began at the site in 1867 under the name Fort D.A. Russel. The base was a major training facility during and after World War II. The majority of the Army training facilities were torn down and not replaced after the base underwent extensive renovation after World War II. Construction since that time has centered on facilities for Air Force operations. Beginning in 1958, the base became a Strategic Air Command (SAC) base. Since then the base has served as an operations center for the Atlas Intercontinental Ballistic Missile (ICBM), the Minuteman I and III, and finally, the Peacekeeper ICBMs. Agricultural land and rural or suburban residential areas border F.E. Warren Air Force Base. The base contains 831 residential housing units and several unaccompanied personnel housing units, along with the services required by residents. The nearest residences to Landfill 5A (LF5A) are off-base, approximately 750 feet to the south. LF5A is an area of about 15 acres located directly south of the Weapons Storage Area (WSA), north of Military Road, and west of Cheyenne Road. The estimated volume of fill is 16,200,000 cubic feet, but the exact depth and thickness of landfill contents, and whether the other landfill units were included as part of this estimated volume, are unknown. The landfill has a thin soil and grass cover. A records search in 1985 revealed that the landfill operated from 1960 until 1970, and consisted of three burn pits and a series of trenches. The operation was a burn, trench-and-fill, and cover operation. Refuse from the base shops and housing areas was transported daily to the landfill. The refuse was deposited in one of the pits and burned for volume reduction; the residue was removed and placed in a trench, and covered with soil.Base refuse disposed of at the landfill was reported as domestic waste and shop wastes such as solvents, waste oils, ethylene glycol, silicone oil, hydraulic fluid, waste JP-4, batteries, battery acid, expired pesticides, old paint, asbestos insulation, and incinerator ash. Field reconnaissance observed the presence of ash, cinders, and construction debris on the surface.The landfill is the source of several chemicals found in groundwater at concentrations of Federal drinking water standards. The chemical most frequently detected is trichloroethylene (TCE).
Remedy:  The selected remedy for LF5A is a source control action that includes capping, an active gas venting system, and if needed, a gas control system for volatile organic compounds (VOCs).The function of the interim action is to control the LF5A site as a source of groundwater contamination by reducing infiltration and the downward movement of contaminants to the groundwater, and by reducing the risks associated with exposure to contaminated materials. While the remedy addresses one of the principal threats at the site, the final remedial action will address remediation of the down-gradient contaminant plume. The major components of the selected remedy include: capping LF5A in accordance with relevant and appropriate Resource Conversation and Recovery Act (RCRA) Subtitle D landfill closure requirements; installing an active venting system to control methane production and a control system, if required for VOCs; installing erosion and surface water controls; and conducting environmental monitoring to ensure the effectiveness of the interim action.
Text:  View full-text ROD [ 66K ]
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