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Record of Decision System (RODS)

HILL AIR FORCE BASE

Abstract

Site Name:  HILL AIR FORCE BASE
Address:  00-ALC/EM 
City & State:  HILL AFB  UT  84056
County:  DAVIS, WEBER
 
EPA ID:  UT0571724350
EPA Region:  08
 
NPL Status:  Currently on the Final NPL
 
ROD Type:  Record of Decision
ROD ID:  EPA/ROD/R08-95/116
ROD Date:  09/28/1995
Operable Unit(s):  03
 
Media:  soil
 
Contaminant:  1,1-dichloroethene, 1,1,1-trichloroethane, tetrachloroethene, toluene, DDT, cadmium, chromium, sodium hydroxide, cyanide, chlorobenzene, benzene, 1,2-dichlorobenzene, 1.4-dichlorobenzene, VOCs, metals, pesticides
 
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 (Hill AFB) is located in northern Utah, about 25 miles north of Salt Lake City and about five miles south of Ogden. Hill AFB covers about 6,700 acres and is located on the Weber Delta, a delta terrace approximately 300 feet above the surrounding valley floors.

Hill AFB has been the site of military activities since 1920 when the western portion of 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 WWII, the Ogden Arsenal manufactured ammunition and was a distribution center for motorized equipment, artillery and general ordnance. The 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 U.S. Army to the U.S. Air Force. Since 1955, Hill AFB has been a major center for missile assembly and aircraft maintenance. Currently, Hill AFB is part of the Air Force Materiel Command.

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 Wastewater Treatment Plant (IWTP), in chemical disposal pits and landfills, and off Base. Disposal in chemical pits and landfills was discontinued by 1980. All waste products are currently treated at the IWTP, recycled on Base, or sent to off-Base treatment or disposal facilities.

Operable Unit 3 (OU3) is a soils-only OU. Operable Unit 3 is located in the southeastern quadrant of Hill AFB, and most of OU3 is located in an industrial area that is used for servicing and maintaining aircraft. In the Layton area south of OU3, the land use varies from residential, to commercial, to 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. Although there is some pastureland, very few livestock are raised on the pastures south of Hill AFB.

The refueling vehicle maintenance facility (RVMC) was used for draining excess fuel from refueling vehicles prior to their maintenance in Building 514. Although the actual source of contaminants in soils under the RVMF is unknown, it is presumed that the drained fuels and any solvents used for parts cleaning in maintenance procedures were collected in a floor drain within RVMF, passed through an oil/water separator, and either disposed of or recycled. The primary contaminants detected in soil at the RVMF include volatile organic compounds (VOCs), base, neutral and acid extractable (BNAE) compounds, pesticides, and metals.

The sodium hydroxide tank site is a former location of two 12,000-gallon underground storage tanks that were used to store a 25 percent by weight solution of sodium hydroxide. During the period the tanks were in use, several hundred thousand gallons of solution were lost, apparently due to leakage. Both tanks were removed in September 1992. Elevated levels of soil pH (resulting from the release of sodium hydroxide solution) were present in subsurface soil. Several metals were also present in concentrations above OU3 background levels.

The Berman Pond site was operated from 1940 to 1956 as an unlined evaporation pond that received stormwater runoff and industrial wastewater, which may have included spent solvents, heavy metals, and hydrocarbons. A cap, consisting of silt and clay, was installed over a portion of the pond in 1986. Soil within and beneath the limits of the former pond is contaminated with VOCs, BNAEs, PCBs, metals, and cyanide.
 
Remedy:  The selected remedy for the refueling vehicle maintenance facility includes the following components: reducing the concentrations of 1,1-dichloroethene in soil using in-situ soil vapor extraction; and implementing institutional controls during the remedial action to prevent human exposure to contaminated soil. These controls include: installing fencing with warning signs to restrict access to the treatment facility; and issuing a continuing order to restrict on-site worker access to the contaminated soil and to restrict or control concrete cutting and excavations in the area unless proper protective equipment is worn.

The selected remedy for the sodium hydroxide tank site includes the following components: an asphalt cap installed over the area of high-pH soil as part of an interim remedial action - the existing cap inspection, maintenance, and repair program will be continued throughout the duration of the action; implementing institutional controls to prevent human exposure to contaminated soil; and limit water seepage through the high-pH soil. These controls will include: issuing a continuing order to restrict on-site worker access to high pH-soil, and restrict or control temporary construction activities unless proper protective equipment is worn; filing a notice to the deed detailing the restrictions of the continuing order; and a covenant to the deed in the event of property transfer.

The selected remedy for Berman Pond includes the following components: extracting perched water contained within the former pond to the extent possible; capping Berman Pond to reduce the potential for exposure to the contaminated soil and minimize water seeping through the soil to groundwater, thereby protecting groundwater quality; implementing a cap inspection, maintenance, and repair program to ensure the long term effectiveness of the cap; and implementing institutional controls to maintain the integrity of the cap. These controls will include: issuing a continuing order to restrict on-site worker access to contaminated soil and restrict construction activities; filing a notice to the deed detailing the restrictions of the continuing order; and a covenant to the deed in the event of property transfer.
 
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