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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/541/R-97/197
ROD Date:  09/30/1997
Operable Unit(s):  06
Media:  Groundwater,Soil,Surface Water,Subsurface Soil
Contaminant:  Trichloroethene, Polychlorinated Biphenyl
Abstract:  Hill Air Force Base (Hill AFB) is located in northern Utah, approximately 25 miles north of Salt Lake City and about 5 miles south of Ogden. Hill AFB occupies approximately 6,700 acres in Davis and Weber counties. Operable Unit 6 (OU 6), one of the nine OUs at Hill AFB, is located entirely within Weber County.The mission of Hill AFB has generally centered on the maintenance and management of aircraft and missiles assembly. There are many on-base industrial facilities that support aircraft, missile, vehicle, and railroad engine maintenance and repair operations. These industrial operations use numerous chemicals, including solvents and degreasers, fuels, acids, bases, and metals. Historically, these chemicals and their associated waste products were disposed of at the Base Industrial Wastewater Treatment Plant (IWTP) in chemical disposal pits, in waste disposal ponds, or in landfills.Most of the on-base buildings within OU 6 have had a varied history of maintenance and testing operations or of playing a support role for these operations. These operations used various solvents for cleaning purposes and fuels for testing purposes. Underground storage tanks (USTs) and associated piping that contained solvents may have leaked and contaminated the soil and groundwater. The specific cause of the release of solvents to the environment is not known. Prior response actions taken by Hill AFB to prevent exposure to contamination associated with OU 6 including the following: providing an alternate source of clean irrigation water to two homes known to be affected by shallow groundwater contamination; and collecting and treating contaminated water from springs and field drains. The treated water is discharged to a storm sewer; extracting and treating contaminated groundwater in the off-base area is part of a removal action described in the Action Memorandum.The provision of alternate water supplies and collecting and treating contaminated water from springs and field drains were actions taken as part of a base-wide removal to address such releases.
Remedy:  The selected remedy for OU 6 is part of a base-wide effort to clean up contaminated groundwater, surface water, and soil. At Hill AFB, the nine OUs are in different stages of investigation or cleanup.The selected remedy addresses groundwater contamination in on-and off-base areas to reduce concentrations of contaminants and prevent further expansion of the contaminant plume. It also addresses contaminants in the subsurface soil.The selected remedy includes the following components: continued operation of the off-base pump and treat groundwater remediation system; collection and treatment of water from contaminated seeps/springs and discharge to storm sewer; collection and treatment of water from spring U6-303 and Cooley's Pond and discharge to shallow aquifer; continued provision of alternate water supplies; a pump and treat system for the on-base portion of the east groundwater contaminant plume; discharge options for the pump and treat system that include injection wells, infiltration fields, and discharge to publicly owned treatment works; natural attenuation for the west groundwater contaminant plume; a groundwater monitoring program; and institutional controls.
Text:  View full-text ROD [ 82K ]
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