PUBLIC HEALTH ASSESSMENT
MOUNTAIN HOME AIR FORCE BASE
MOUNTAIN HOME, ELMORE COUNTY, IDAHO
Mountain Home Air Force Base (Mountain Home AFB) is located approximately 50 miles southeast of Boise and 10 miles southwest of the city of Mountain Home in Elmore County, Idaho. The main base occupies 5,800 acres on the Mountain Home Plateau and 115,019 acres at eight satellite sites. The Mountain Home Plateau is bordered by the Danksin Mountains to the north and by the Snake River to the south.
The U.S. Department of Defense established Mountain Home AFB in 1943 as a training base for bombardment groups during World War II. The base was deactivated in 1945, only to be reactivated as a Strategic Air Command Base (SAC) in 1948, and then deactivated again in 1950. In 1951, the base was assigned to the Military Air Transport Services and was used as a training base for the Aerial Resupply and Communication Wings until 1953. The Bombardment Wing was stationed at Mountain Home AFB between 1953 and 1964 (Air Force, 1997b).
Between 1960 and 1965, three Titan I missile complexes were constructed and operated at Mountain Home AFB. The Tactical Air Command assumed control of the base from the SAC in 1965. Since 1972, the 366th Tactical Fighter Wing and the 390th Electronic Combat Squadron have occupied the base (Air Force, 1997b). In 1992, the Air Combat Command assumed control of Mountain Home Air Force Base.
The U.S. Environmental Protection Agency (EPA) placed Mountain Home AFB on the National Priority List on August 30, 1990, as a result of concerns regarding groundwater contamination throughout the base, and soil contamination at the Fire Training Area and a closed sanitary landfill. Contaminants of potential concern are metals, volatile organic compounds, and petroleum hydrocarbons.
The Agency for Toxic Substances and Disease Registry (ATSDR) conducted a site visit in August 1991 and again in December 1997. No immediate public health hazards or community health concerns were identified during these visits.
Based on an evaluation of available environmental information, ATSDR reached the following conclusions and assigned a public health hazard conclusion category.
On the basis of a review of available information on contamination of soil, groundwater, and
surface water and sediment, ATSDR concludes that Mountain Home AFB should be assigned to
the No Apparent Public Health Hazard category.
Site Description and Operational History
Mountain Home Air Force Base (Mountain Home AFB) is located approximately 50 miles southeast of Boise and 10 miles southwest of the city of Mountain Home in Elmore County, Idaho (Figure 1). The main base occupies 5,800 acres on the Mountain Home Plateau and 115,019 acres at eight satellite sites that were not evaluated in this report. The Mountain Home Plateau is bordered by the Danksin Mountains to the north and by the Snake River to the south.
The U.S. Department of Defense established Mountain Home AFB in 1943 as a training base for bombardment groups during World War II. The base was deactivated in 1945, only to be reactivated as a Strategic Air Command Base (SAC) in 1948, and then deactivated again in 1950. In 1951, the base was assigned to the Military Air Transport Services (MATS) and was used as a training base for the Aerial Resupply and Communication (ARC) Wings until 1953. The Bombardment Wing was stationed at Mountain Home AFB between 1953 and 1964 (Air Force, 1997b).
Between 1960 and 1965, three Titan I missile complexes were constructed and operated at Mountain Home AFB. The Tactical Air Command (TAC) assumed control of the base from the SAC in 1965. Since 1972, the 366th Tactical Fighter Wing and the 390th Electronic Combat Squadron have occupied the base (Air Force, 1997b). In 1992, the Air Combat Command assumed control of Mountain Home Air Force Base.
Past activities involving hazardous materials at Mountain Home AFB include combustion of fuel, oil, and lubricants during fire training exercises; fuel storage and refueling; disposal of waste oil/degreasing solvent; fuel spills from the flight line fuel system and underground storage tanks; storage and use of pesticides and application equipment, and wastewater discharge from cleaning of pesticide application equipment; burial of small amounts of radioactive waste, corker material (boron composite material), and excess World War II supplies; disposal of munitions; disposal of solid waste; and leakage from oil/water separators. The base also contains a sanitary landfill and several wastewater lagoons.
Remedial and Regulatory History
In July 1983, the Air Force initiated an Installation Restoration Program (IRP) to identify, investigate, and cleanup past disposal sites at Mountain Home AFB The program identified 33 sites for investigation (Figure 2). The U.S. Environmental Protection Agency (EPA) placed Mountain Home AFB on the National Priority List (NPL) on August 30, 1990, as a result of concerns regarding groundwater contamination throughout the base, and soil contamination at the Fire Training Area and a closed sanitary landfill. A Federal Facilities Agreement (FFA) was signed on January 16, 1992, by the Air Force, EPA (Region 10), and Idaho Department of Health and Welfare (IDHW), to establish a schedule for investigations, interim actions, and required remedial actions at the sites.
The hazardous waste sites at Mountain Home AFB are grouped into six operable units (OU): OU-1 consists of 20 sites that were determined not to pose a health risk and required no further action; OU-2 consists of two former landfills; OU-3 consists of basewide groundwater; OU-4 consists of the Fire Training Area 8; OU-5 consists of a low-level radioactive waste disposal area; and OU-6 consists of sites which were determined as part of OU-1 to pose a potential risk to human health and required further evaluation.
Thirty-one (31) of the 33 sites identified by the IRP (Table 1) are considered Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) Superfund sites while the other two were addressed under the Resource Conservation and Recovery Act (RCRA); one has monitoring requirements and the other has been closed and is considered to be "clean." A Record of Decision (ROD) was reached for OUs 1, 3, 5, and 6 in October 1995. Two previous RODs had been signed in June 1992 (OU 4) and in May 1993 (OU 2). Of the thirty-one CERCLA Superfund sites, thirty were classified as requiring "No Remedial Action" (NRA) and the remaining site was classified as requiring Limited Action Long Term Monitoring (LTM). LTM was also required for the groundwater at all the NRA sites.
In 1995, investigations began at the eight satellite RCRA sites, under a Corrective Action Plan. The results of the RCRA Facilities Assessment indicated that for seven of the eight sites no further action was required. The eighth site, the basewide oil/water separators, has been decommissioned and associated underground storage tanks have been removed. A final Oil/Water Decommissioning Report recommended no further action and comments on the report are pending from participating agencies.
The Agency for Toxic Substances and Disease Registry (ATSDR) conducted an initial site visit in August 1991 and met with representatives from the Air Force and IDHW to determine whether any potential health hazards were associated with the site. There were no community health concerns reported by the base health officials or IDHW (ATSDR, 1991). ATSDR conducted another site visit in December 1997 to confirm that there are no immediate public health threats and to identify community health concerns.
Concerns solicited by community interviews conducted by the Air Force as part of their community relations plan were limited to jet aircraft noise, range expansion, exposure to asbestos-containing materials, and lead-based paint issues (Air Force, 1997c).
The population of Mountain Home AFB is approximately 6,024, of which 56.5 % is male. The population of the base is primarily white (84%) and English-speaking (75%) (Figure 3, U.S. Census, 1990). There are 1,522 families with 2,340 children living on the base (U.S. Census, 1990). The average tour of duty at Mountain Home AFB is three years (Air Force, 1997c).
An additional 9,100 residents live in the city of Mountain Home and surrounding areas (Air Force, 1997b). The off-base population density averages about two people per square mile.
The Mountain Home Plateau, on which the Mountain Home AFB is located, is a rolling upland plain covered with lava and windblown sediment. Surface water run-off is limited to the winter snowmelt. There are no naturally occurring surface water bodies on the base. The climate is arid and the average annual precipitation is about 8 inches. There is very little water in the soil as most of the precipitation is lost to evaporation. Due to the limited precipitation, irrigation is necessary for agricultural production. The base's drinking water supply is obtained from the regional groundwater aquifer and is a separate system from the municipal drinking water supply for the town of Mountain Home.
The majority of the land around the base is owned by the federal government and is managed by the Bureau of Land Management (BLM). This land is used primarily for grazing cattle. Private land borders the western, eastern, and southern boundaries of Mountain Home AFB. The nearest surface water bodies to the base are the Snake River (2.5 miles south), Canyon Creek (4 miles west), and Rattlesnake Creek (> 4 miles east). Large blocks of privately owned land are located around the Rattlesnake and Canyon Creeks as well as the Snake River. The land use is predominantly agricultural, with the major crops consisting of hay, alfalfa, sugar beets, wheat, and potatoes. A feedlot and a hazardous waste receiving facility are located 10 miles and 16 miles east of the base, respectively. It is assumed that the future land use of this area will remain agricultural. The soils in the area are wind-blown silt and sand.
Quality Assurance and Quality Control
In preparing this public health assessment (PHA), ATSDR relied on information provided in the referenced documents and contacts. The agency assumes adequate quality control assurance and control measures were followed with regard to chain of custody, laboratory procedures, and data reporting. The validity of the analyses and conclusions drawn in this document are determined by the reliability of the referenced information.
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