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Record of Decision System (RODS)



Address:  00-ALC/EM 
City & State:  HILL AFB  UT  84056
EPA ID:  UT0571724350
EPA Region:  08
NPL Status:  Currently on the Final NPL
ROD Type:  Record of Decision
ROD ID:  EPA/ROD/R08-95/115
ROD Date:  09/28/1995
Operable Unit(s):  07
Media:  soil
Contaminant:  VOCs, metals, chromium, cadmium, hexavalent chromium, PCBs, mercury, chlorinated dibenzofurans, cyanide, BNAE
Abstract:  Please note that the text in this document summarizes the Record of Decision for the purposes of facilitating searching and retrieving key text on the ROD. It is not the officially approved abstract drafted by the EPA Regional offices. Once EPA Headquarters receives the official abstract, this text will be replaced.

Hill Air Force Base (AFB) is located in northern Utah, about 25 miles north of Salt Lake City and 5 miles south of Ogden, Utah. Hill AFB covers 6,700 acres on the Weber River Delta, a terrace that lies about 300 feet above the surrounding valleys.

Most of the southern part of Hill AFB is occupied by industrial facilities, equipment storage areas, and administration buildings related to the aircraft maintenance mission of the base. By contrast, the northern part of Hill AFB has large open areas with groups of buildings that were constructed as munition manufacturing plants, assembly plants, or storage facilities. Although the use of the old plants and storage facilities has changed in recent years to missile storage, maintenance, and testing, the buildings and facilities remain. Off-base land use includes residential, commercial, and agricultural. This area has undergone rapid residential development over the last 10 to 20 years, and agricultural use has declined. Crop production in the agricultural areas primarily is the cereal grains, wheat and barley, and alfalfa. There is some pasture land, and in some areas livestock are raised. The site was placed on the National Priorities List (NPL) because of several sites where hazardous liquid and solid wastes generated by installation operations were disposed.

Operable Unit 7 (OU7) is a soils-only OU and consists of soil contamination at several source areas in and around Buildings 220 and 225, and some imported fill at Base Supply Well 6. The two buildings lie in the south central portion of the base, west of the main runway in an industrial area that has been used to service aircraft since the 1940s. Base Supply Well 6 is located northwest of the north end of the main runway. Subsurface conditions in these areas are dominated by interbedded silty sand, sandy silt, and clay. Groundwater beneath OU7 is addressed separately in OU 8.

Hill AFB has been the site of military activities since 1920, when the western portion of what is now the base was activated as the Ogden Arsenal, an Army Reserve Depot. In 1940 and 1941, four runways were built and the Ogden Air Depot was activated. During World War II, the Ogden Arsenal manufactured ammunition and was a distribution center for motorized equipment, artillery, and general ordnance. The Ogden Air Depot's primary operation was aircraft rehabilitation. In 1948, the Ogden Air Depot was renamed Hill AFB, and in 1955, the Ogden Arsenal was transferred from the Army to the Air Force. Since 1955, Hill AFB has been a major center for missile assembly and aircraft maintenance.

On-base industrial processes associated with aircraft, missile, vehicle, and railroad engine maintenance and repair include metal plating, degreasing, paint stripping, and painting. These processes use numerous chemicals including chlorinated and non-chlorinated solvents and degreasers, petroleum hydrocarbons, acids, bases, and metals. In the past, chemicals and waste products were disposed of at the Industrial Waste Treatment Plant in chemical disposal pits and landfills and off base. Disposal in chemical pits and landfills was discontinued by 1980. All wastes currently are treated at the ITWP, recycled on base, or sent to off-base treatment or disposal facilities.
Remedy:  The major components of the selected remedy for Hill AFB OU7 include: groundwater quality monitoring in areas upgradient, beneath, and downgradient of the area where contaminant concentrations in soils are approximately at health-based risk levels; soil moisture content monitoring around the perimeter of and within the area of contaminated soils; maintaining and preserving the building and floor slab that overlay the contaminated soils; issuance of a continuing order from the base commander that will restrict worker access to the contaminated soils as long as Hill AFB owns the property; a notice to the deed that will be filed by the Air Force detailing the restrictions of the continuing order; a covenant in the deed that incorporated the restrictions of the continuing order and upon transfer of the property, established the locations and restrictions of use of the contaminated area and retained rights of access for future response actions, if needed (if land use is changed or Building 225 is removed, the Air Force will reevaluate the protectiveness of the selected remedy and perform any necessary remedial actions); and posting warning signs regarding the presence of contaminated soils that could present a threat to human health.
Text:  View full-text ROD [ 138K ]
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