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Home > Site Information
Hill AFB
Operable Units:
OU 3
OU 7
OU 11
OU 13
HAFB Project Manager: Mark Roginske
Site Overview
Operable Unit 3 (OU-3) includes four sites located in the southeast portion of Hill AFB near the South Gate entrance and one closed site just outside the southeast base boundary. OU-3 deals only with contaminated soil. Groundwater beneath OU-3 is addressed separately as part of Operable Unit 8 (OU-8) and is discussed in the OU-8 fact sheet. The five sites included in OU-3 are:
- Sodium Hydroxide Tank
- Berman Pond
- IWTP Sludge Drying Beds
- Building 514
- Pond 2
Sodium Hydroxide Spill
In 1950, two 12,000-gallon storage tanks were built to hold a sodium hydroxide solution that was used as part of operations at Hill’s Industrial Waste Treatment Plant (IWTP). In the 1980s, several hundred thousand gallons of the solution leaked into the soil. Both tanks were removed in 1992 in accordance with Utah Department of Environmental Quality (UDEQ) requirements.
Berman Pond
From 1940 to 1956, Berman Pond was operated as an unlined evaporation pond that received storm water runoff and industrial wastewater, which included spent cleaning solvents, heavy metals and hydrocarbons. The pond was taken out of service after the IWTP was constructed in 1958. The abandoned pond was filled with rubble and soil in the mid 1960s. The contaminants at Berman Pond consist of a variety of cleaning solvents, metals used in plating solutions, and petroleum hydrocarbons.
Sludge Drying Beds
Waste sludge from the IWTP, consisting of paint stripping, chrome plating and degreasing wastes, was pumped to two sludge drying bed areas to be stored and dried. Investigations began at the IWTP sludge drying beds in 1985 to determine if there was a potential for soil and groundwater contamination. No contamination was found. Since it was determined that there was no current or future threat to the soils and groundwater beneath the sludge beds, cleanup actions were not necessary, and the site was closed in 1995.
Building 514
Bldg. 514, the Refueling Vehicle Maintenance Facility (RVMF), was used for draining excess fuel from the refueling vehicles until 1985. Cleaning solvents were also used for the maintenance of the refuelers. RVMF activities led to the contamination of the soil which was treated with a soil vapor extraction (SVE) system that was installed in 1997. The site was closed in 2001.
Pond 2
Pond 2 was a storm water pond located outside the southeast base boundary that received occasional runoff from Hill AFB until 1974. Use of the pond was discontinued because the storm water was rerouted to Pond 3 on-base. Samples were collected from the soil in Pond 2, and no contaminants were found. Cleanup remedies were not needed at Pond 2, and the property was placed back into public use. The site was closed in 1995.
Health Risk Issues
The OU-3 contamination has not affected local drinking water supplies due to the subsurface geology at the site. The drinking water for Hill and surrounding communities comes from deep aquifers and mountain reservoirs, not from the contaminated shallow groundwater aquifer. In addition, the deep and shallow aquifers are separated by numerous clay layers that prevent contamination from moving downward.
There are no areas of contamination off the base, therefore, there is no risk to local residents.
Cleanup Actions
Only two of the five sites in OU-3, the Sodium Hydroxide Tank and Berman Pond, require cleanup and have remedies in place. The other three sites have either had remedies that were successfully implemented and since shut down, or required no action based on findings from investigations.
Once the two sodium hydroxide tanks were removed in 1992, the area was backfilled and an asphalt cap was constructed to cover the contaminated soil. The original cap was covered with a more permanent asphalt cap in 1999 and covers an area of approximately 29,000 square feet. The cap is inspected annually to ensure that it continues to perform as designed. Hill is performing an investigation to determine if the Sodium Hydroxide site may be closed.
A soil cap was installed over a portion of Berman Pond in 1984, but it was not effective at preventing water runoff from coming into contact with the contaminated soil because it did not cover the entire area of the pond. In 1986, an additional temporary cap, consisting of clay and silt, was installed over a portion of the pond. Furthermore, as part of the 1995 Record of Decision (ROD), the old cap was removed and the entire pond was capped with a special asphalt layer in 1997 that significantly reduced the potential for infiltration of water. A dewatering system was also placed at the bottom of the former pond with the intent of removing any perched water. This system has been turned off pending additional studies.
Hill is evaluating whether potential contamination from Berman Pond is being captured by the base boundary hydraulic containment system.
The Air Force continues to monitor contamination levels at OU-3.
What’s Ahead
The Air Force will continue maintaining and managing the cleanup remedies in place to be sure they continue to perform as designed. The asphalt caps at the Sodium Hydroxide Tanks and Berman Pond locations are inspected on an annual basis.
The Air Force will complete a Five-Year Review in 2013 as required by environmental clean-up laws. This review is done to verify that treatment systems and ongoing studies are protecting human health and the environment and are meeting clean-up goals. The public has the opportunity to participate in this review.
Hill environmental cleanup documents are available for viewing by the public at the Hill Information Repository located at the Stewart Library on the Weber State University (WSU) campus in Ogden and at WSU’s Davis Campus Library in Layton. For hours of operation at the libraries, call the Stewart Library at (801) 626-6403 or the WSU Davis Library at (801) 395-3472.
Current as of July 2010
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HAFB Project Manager: Mark Roginske
Site Overview
Operable Unit 7 (OU-7) includes a collection of sites, three of which are located in the base’s industrial complex on the southeast portion of the base. The fourth is located in Layton. The four sites associated with OU-7 are:
- Building 225 Chromium Spill
- Building 225 PCB Spill
- Building 220 Underground Storage Tanks
- Layton Farm Property
Building 225 Chromium Spill
From the 1940s through 1972, Bldg. 225 housed a metal plating shop located along the east side of the building. Plating solution tanks were frequently emptied into the floor drain system which then emptied into the industrial waste pipeline. These tanks contained chromic acids and other chemicals used in the plating process. Over time, the plating solutions corroded the clay and concrete pipes and leaked waste liquids into the soil beneath the building, contaminating the groundwater beneath 120 feet. As part of the 1995 Record of Decision that was signed by the Air Force, the Utah Department of Environmental Quality and the Environmental Protection Agency, the building floor was defined as an excellent barrier to prevent water from infiltrating into the contaminated soil and carrying any more contamination to the groundwater below. Groundwater contamination beneath the site is being addressed separately as part of OU-8.
Building 225 PCB Spill
In 1989, unusual odors and discolored soil was discovered during the excavation of a utility trench. The site, approximately 100 feet west of the former metal plating shop beneath Bldg. 225, was found to be contaminated with polychlorinated biphenyls (PCBs). The site was a former transformer storage area that had been removed in the 1960s. After the removal of most of the contaminated soil, it was found that only trace levels of PCBs remained that would not require additional clean-up. The site was closed in 1996.
Building 220 Underground Storage Tanks
Bldg. 220, located east of Bldg. 225 and adjacent to the main runway, has been used as an aircraft painting and paint stripping facility. Up until 1986, underground storage tanks were used to separate paint chips and sludge from the wastewater solutions during paint stripping operations. During the renovation of Bldg. 220 in 1986, soil samples collected near the old storage tanks showed that some of the piping may have leaked paint stripping waste into the soil. After the contaminated soil was removed from the site, soil sampling verified that no additional cleanup actions were needed because the remaining concentrations of contaminants were not significant. The site was closed in 1995.
Layton Farm Property
In 1989, chromium-contaminated soil, taken from Bldg. 225 at Hill AFB during trench excavation for utility installation, was inadvertently placed in two locations on a farm in Layton, approximately one mile south of Hill. This farm was accepting fill material from various sources from throughout North Davis County. All of the contaminated soil originating from the Bldg. 225 site was identified and removed to a hazardous waste landfill west of Salt Lake City. The Utah Department of Health certified the site was clean in 1991, and the site was closed that same year.
Health Risk Issues
The OU-7 contamination has not affected local drinking water supplies because of the subsurface geology at the site. The drinking water for Hill and surrounding communities comes from deep aquifers and mountain reservoirs, not from the contaminated shallow groundwater aquifer. In addition, the deep and shallow aquifers are separated by a thick clay layer that prevents contamination from moving downward.
Since the contamination in Layton has been cleaned up, there is no known risk to Layton residents. The only potential risk is to base workers in Bldg. 225. However, this risk is minimal as the areas of contamination are either below risk-based levels, or they are beneath concrete floor slabs in existing buildings that prevent exposure to people and animals, according to the Baseline Risk Assessment for OU-7. Also, the buildings and surrounding asphalt and concrete covered areas act as a barrier to precipitation and other fluids that could carry the contaminants from the soil to the groundwater below.
Cleanup Actions
The concrete floor in the former Metal Plating Shop currently covers the area of contaminated soil in Bldg. 225. The soil is monitored for moisture within the area of contamination to ensure that water is not coming into contact with the contaminated soil and transporting contaminants to the groundwater. The Air Force has placed digging restrictions on the area in Bldg. 225, limiting worker access to the contaminated soils. Warning signs are also posted to alert everyone about the presence of contaminated soils that could present a threat to human health.
If Bldg. 225 were to be removed, an investigation would occur and any contaminated soil that does not meet appropriate health levels would be treated in place or removed.
After the removal of contaminated soil at the PCB spill site in Bldg. 225 and the underground storage tank area in Bldg. 220, it was found that both sites did not have significant levels of contaminants. No additional cleanup actions were required at these sites because the levels of contaminants were low and they did not pose a future health threat.
At the Layton farm site, confirmation testing was conducted to be sure the chromium-contaminated soil had been removed. Since the threat of exposure had been removed, no further action was required or taken at this site.
What’s Ahead
The Air Force will maintain and manage the floor over the contaminated soil at Bldg. 225 to ensure it meets the cleanup requirements.
The Air Force will complete a Five-Year Review in 2013 as required by environmental clean-up laws. This review is done to verify that treatment systems and ongoing studies are protecting human health and the environment and are meeting clean-up goals. The public has the opportunity to participate in this review.
Hill environmental cleanup documents are available for viewing by the public at the Hill Information Repository located at the Stewart Library on the Weber State University (WSU) campus in Ogden and at WSU’s Davis Campus Library in Layton. For hours of operation at the libraries, call the Stewart Library at (801) 626-6403 or the WSU Davis Library at (801) 395-3472.
Current as of July 2010
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HAFB Project Manager: Mark Roginske
September 2011 Update
A feasibility study to determine the best cleanup solution for this site was completed in March 2011; however,
Hill was granted a timeline extension in order to gather more data. Additional data will allow Hill to make better
remedial decisions based on a more complete understanding of all site characteristics. A proposed plan for cleanup
will be presented in December 2012.
Meanwhile, Hill is in the process of removing fuel-related contamination at the base gas station (i.e. source area).
Fuel-related contaminants float on top of the water and can be easily removed by hand or with skimmers.
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Site Overview
Operable Unit 11 (OU-11) consists of one site on Hill AFB where a former gas station and auto parts and repair facility was located. This facility (former Building 454) was located at the corner of 6th Street and E Avenue on Hill until 1999 when it was torn down to allow for construction of a new mini mart and gas station to the northwest.
The variety of contaminants at OU-11 suggests they originated from Building 454’s leaking underground diesel and gasoline tanks, as well as from an oil/water separator and degreasing solvents used during auto maintenance activities. The primary chemicals of concern at OU-11 include:
- Benzene, toluene, ethylbenzene, xylenes, and naphthalene (BTEXN compounds), chemicals associated with gasoline and diesel fuels
- Trichloroethene (TCE), a degreasing solvent
- Methyl tertiary-butyl ether (MTBE), an additive to gasoline
Building 454 was first investigated in 1996 (as part of the Operable Unit 9 Site Investigation) to determine if the oil-water separator in the building had released contaminants into the environment. Three monitoring wells were installed. TCE, a solvent commonly used to clean aircraft and machine parts, was found in one of the wells.
Once TCE was found, it was decided that the contaminated groundwater would be managed under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), and the site became Operable Unit 11.
In 1999, during the installation of additional monitoring wells, a small plume of gasoline was discovered floating on top of the groundwater just downgradient from the former location of the underground storage tanks. The plume of gasoline and the soils contaminated from this release are being addressed under the Leaking Underground Storage Tank program with the Utah Department of Environmental Quality.
Health Risk Issues
The OU-11 contamination has not affected local drinking water supplies due to the subsurface geology at the site. The drinking water for Hill AFB and surrounding communities comes from deep aquifers and mountain reservoirs, not from the contaminated shallow groundwater aquifer. In addition, the deep and shallow aquifers are separated by a thick clay layer that prevents contamination from moving downward.
The contamination in OU-11 is moving southwest toward military family housing areas, but has not yet reached the housing.
According to the Baseline Risk Assessment for OU-11, the only known pathway of exposure for base workers is through inhaling chemical vapors that may enter buildings through floor slabs.
Cleanup Actions
A soil vapor extraction (SVE) system was installed in 2002 to address the contaminated soils and to promote the evaporation of the gasoline floating on the surface of the groundwater at the site so that it can be captured and removed. To date, the SVE system has removed more than 5,000 gallons of contaminants from the soil. In addition, Hill has removed approximately 200 gallons of gasoline floating on the surface of shallow groundwater through manual bailing of monitoring wells.
Since 2008, local groundwater levels have risen more than nine feet, making the SVE system unreliable. Hill AFB is currently investigating alternative technologies and methods to reactivate the SVE system.
Gasoline floating on the surface of the groundwater is continuing to be removed through manual bailing. Passive skimmers were also installed in various monitoring wells to remove more gasoline.
The Air Force will continue to monitor contamination levels at OU-11.
What’s Ahead
The remedial investigation for OU-11 was completed in 2005. The Air Force has begun evaluating potential cleanup actions such as using a pump and treat system to contain the contaminant plumes while allowing them to naturally degrade below cleanup levels. Hill AFB is also evaluating the possibility of using enhanced bioremediation as a more economical and “greener” cleanup alternative at OU-11. The public will be asked to comment on any cleanup actions that are proposed for implementation.
The Air Force will complete a Five-Year Review in 2013 as required by environmental clean-up laws. This review is done to verify that treatment systems and ongoing studies are protecting human health and the environment and are meeting clean-up goals. The public has the opportunity to participate in this review.
Hill environmental cleanup documents are available for viewing by the public at the Hill Information Repository located at the Stewart Library on the Weber State University (WSU) campus in Ogden and at WSU’s Davis Campus Library in Layton. For hours of operation at the libraries, call the Stewart Library at (801) 626-6403 or the WSU Davis Library at (801) 395-3472.
Current as of July 2010
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HAFB Project Manager: Mark Roginske
Click here to go to the PCB Information Page
September 2011 Update
Polychlorinated biphenyls (PCBs) were removed from the on-base housing area located in the southwest corner of the base
in 2007 and 2010 under a Time Critical Removal Action (TRCA). Due to the nature of the TCRA, the Environmental Protection
Agency initially determined there was no need for the Air Force to do a Feasibility Study, which is a detailed evaluation
of site cleanup options. However, during the regulatory review of the Record of Decision, the EPA decided that a Feasibility
Study was required to satisfy all the requirements of the law. Hill is now preparing a Feasibility Study, which will
evaluate options for cleaning up contamination that was not addressed as part of the TCRA. This includes contaminated soil
under buildings, sidewalks and streets. At the conclusion of the Feasibility Study, the Air Force will present a plan to
address the remaining contamination. As these structures are removed, the contamination will be removed as outlined in the
plan. The plan will be presented for public review and comment in early 2012.
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Site Overview
Operable Unit 13 (OU-13) consists of approximately 100 housing units in Upper Area F of the military family housing area on Hill AFB. Upper Area F is located on the southwest side of the base adjacent to the Southwest Gate. Hill AFB’s military family housing is operated by Boyer Hill Military Housing (BHMH), which assumed ownership of all base housing in 2005.
In February 2007, polychlorinated biphenyls, or PCBs, were discovered in shallow soils near a housing unit. Subsequent samples taken shortly after the discovery identified additional areas of PCB-contamination. PCBs are chemicals commonly found in electrical transformers. They are now banned in the United States.
Once the sampling results were confirmed, the Air Force notified the residents of what was found and began a comprehensive soil investigation in Upper Area F. Over the next four months, approximately 1,400 soil samples were taken in the area. At the conclusion of the investigation, a total of six areas were identified as having PCBs in the soil above the residential clean-up standard of 1 part per million. PCBs were only found in the upper four feet of soil. The source of the PCBs is believed to be an old storage area at the nearby Defense Reutilization and Marketing Office (DRMO). Historical records show that a portion of the housing area was built over this storage area, which stored electrical transformers -- a common source of PCBs. As the housing area was constructed and graded, contaminated soil from the storage area was likely used as part of the backfill.
Cleanup Remedies
In September 2007 the Air Force began a Time-Critical Removal Action (TCRA) under the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA). For sites where contamination can have an impact to the public, immediate action is taken to remove the hazard. The goal of the cleanup was to remove all accessible PCB-contaminated soil above the residential clean-up standard of 1 part per million up to a depth of four feet below the ground surface.
Soil samples taken during the cleanup action determined the exact area and depth of the excavation. All soils with PCB detections above 1 part per million (ppm) were removed. In total, approximately 2,285 cubic yards of contaminated soil were removed. The excavation sites were backfilled with clean soil and the landscaping was restored.
The cleanup performed under the TCRA satisfies all the remedial action objectives, which were set forth by the Air Force and approved by the U.S. Environmental Protection Agency and the Utah Department of Environmental Quality.
What’s Ahead
The proposed plan was released to the public in March 2010. Any public comments received will be included in the Record of Decision (ROD), which is a formal decision document that explains which cleanup remedies will be used to clean up the site. The ROD is signed by the Air Force, EPA, and UDEQ. The OU-13 ROD is expected to be completed in early 2011.
Subsequent excavation of soil with PCBs in excess of 1 ppm will be performed under roads and housing units as the Air Force abandons and demolishes these units.
Until such time as the PCB-contaminated soil can be removed, existing land use controls will be maintained to ensure protectiveness to human health.
The Air Force will complete a Five-Year Review in 2013 as required by environmental clean-up laws. This review is done to verify that treatment systems and ongoing studies are protecting human health and the environment and are meeting clean-up goals. The public has the opportunity to participate in this review.
All Hill environmental cleanup documents are available for viewing by the public at the Hill Information Repository located at the Stewart Library on the Weber State University (WSU) campus in Ogden and at WSU’s Davis Campus Library in Layton. For hours of operation at the libraries, call the Stewart Library at (801) 626-6403 or the WSU Davis Library at (801) 395-3472.
Current as of July 2010
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