PUBLIC HEALTH ASSESSMENT
FORT WAINWRIGHT
FORT WAINWRIGHT, FAIRBANKS NORTH STAR BOROUGH, ALASKA
The Agency for Toxic Substances and Disease Registry (ATSDR) prepared this public health assessment (PHA) to evaluate exposure pathways and to respond to community members' concerns about past and current exposures to contaminants originating at Fort Wainwright, Alaska. On the basis of available information, ATSDR found that people who live or work at Fort Wainwright or the neighboring area are not at risk of exposure to harmful levels of contaminants from the post.
Fort Wainwright was activated in 1938 and is an active U.S. Army installation consisting of 915,000 acres in Fairbanks, North Star Borough, Alaska. Accidents and/or waste management practices over the years have resulted in spills or releases of industrial materials onto the soil or the underlying groundwater of the installation. The most common contaminants at the post are volatile organic compounds (VOCs); pesticides; polychlorinated biphenyls (PCBs); and petroleum, oils, and lubricants.
In coordination with the Alaska Department of Environmental Conservation and the U. S. Environmental Protection Agency (EPA), the Army has been investigating and remediating all known sources of on-post environmental contamination. Using data obtained from these efforts, ATSDR has assessed potential exposure pathways (via groundwater, soil, and air) at the site. ATSDR did not identify public health hazards associated with the majority of the on-post contaminated sites because (1) they are not widely accessible by the public, (2) they contain only low levels of contamination, or (3) remedial activities to remove contaminants were completed.
ATSDR identified three situations in which people were or could have been exposed to site-related contamination in the past: (1) drinking water containing low-level contaminants from the Shannon Park Baptist Church well (1985-1991) and the Church of Latter Day Saints' Steese Chapel Hall well (before 1991); (2) inhalation of pollutants emitted from the Fort Wainwright coal-fired power plant and soil vapor extraction and air sparging systems (SVE/AS); and (3) incidental exposures (via dermal contact, ingestion, or inhalation) to coal ash used as road grit. ATSDR concluded that exposures to contaminants in the water, road grit, or emissions from the SVE/AS would not have exposed local community members, base residents, or base workers to contaminants often enough or at high enough levels for there to be a health concern. Since exposure to the contaminated groundwater and road grit has stopped, these situations pose no current or future public health hazards. ATSDR concluded that ambient air concentrations of pollutants released by the coal-fired power plant could have exceeded National Ambient Air Quality Standards while the power plant was burning coal sprayed with waste oil or operating without appropriate pollution control equipment. The nearby school and residential units could have been within the affected area when they were downwind of the plant's stacks. No measurements are available to confirm whether exposures have occurred.
ATSDR also identified several possible current exposure situations.
Fort Wainwright is an active installation covering approximately 915,000 acres in the Fairbanks North Star Borough, Alaska. It is approximately 120 miles south of the Arctic Circle, and 350 miles north of Anchorage, in the interior part of the state (Figure 1). Fort Wainwright lies within the flood plain of the Chena River, which is a tributary of the Tanana River. The Chena River meanders westward through the main post area, forming several oxbows. The Chena River drains approximately 2,000 square miles and flows into the Tanana River approximately 8 miles west-southwest of Fort Wainwright (Harding Lawson 1997).
Fort Wainwright is divided roughly into four noncontiguous areas: the Main Post, Tanana Flats Training Area, Fort Wainwright (Yukon) Maneuver Area, and a range complex. The Main Post Area (figure 2) covers 4,473 acres, which are divided by the Fort Wainwright Army Airfield. The Tanana Flats Training Area (also known as the Blair Lakes Maneuver Area) is a 642,215-acre training area located south of the main post. The area is laced with creeks and marshland. The Fort Wainwright (Yukon) Maneuver Area covers about 261,000 acres. It is located southeast of the main post, adjacent to Eielson Air Force Base. In addition, the range complex covers about 8,825 acres between the main post and the Tanana Flats Training Area (Harding Lawson 1994a).
Fort Wainwright, originally referred to as Ladd Army Airfield and Ladd Air Force Base, has been in continuous service by the military since 1938. During World War II, Ladd Field was the transfer point for the U.S.-Soviet Lend Lease program. From 1942 to 1945, almost 8,000 aircraft were transferred to Soviet aircrews at Ladd Field. Following World War II, the military began conducting large-scale, winter-weather training in Alaska, as well as defending Alaska from the Soviet Cold War threat. In January 1961, the Army assumed control of Ladd Air Force Base and renamed it Fort Wainwright. During the 1967 Chena River flood and in its aftermath, Fort Wainwright soldiers provided equipment and manpower for evacuation, protection, and cleanup of the devastated area. Fort Wainwright was also the site of a Defense Fuel Support Point, which served as a transfer station for military fuel supplies in central Alaska.
Currently, the primary mission of the installation is to train U.S. Army infantry soldiers in the arctic environment and to prepare troops for rapid deployment worldwide (ADEC and EPA 1990). Industrial operations at the installation are limited to maintenance of fixed-wing aircraft, helicopters, and vehicles, as well as support activities necessary for operation. The Fairbanks-Eielson Pipeline (FEP), that provided fuel to the base until July 1992, runs through the northern part of the main cantonment area (HartCrowser 1997c).
Over the decades of military use, routine operations and storage practices resulted in accidental releases of chemicals to the ground. Some chemicals also seeped into the underlying groundwater or entered nearby surface water. Former waste disposal practices are also responsible for releases to the environment. Disposal of most non-hazardous waste was in the sanitary landfill, located north of the Chena River. Initially, waste material was burned in trenches and then covered with fill. During the 1960s, the standard operation changed to the current practice of compacting waste material and covering it with fill. Naturally occurring surface depressions were used for disposal of waste construction material and covered with fill. Other waste disposal practices at Fort Wainwright included using waste oils on post roads for dust control and for fire-fighting drills; collecting hazardous waste in waste oil tanks and burning it for energy recovery in the power plant; and discharging or dispersing used oils, solvents, or fuel spills into floor drains in buildings across the installation (Harding Lawson 1992).
Fort Wainwright generated hazardous waste material in the past, including pesticides; polychlorinated biphenyls (PCBs); petroleum, oils, and lubricants (POLs); and battery fluids. Such chemicals were largely associated with spent solvents and ignitable wastes from aircraft and vehicle maintenance shops; contaminated motor vehicle and aviation fuels; painting waste; and spent non-recyclable vehicle batteries. Fort Wainwright received small quantities of radioactive tritium waste and low-level radioactive materials (e.g., radium dials). Disposal of these materials was at the Birch Hill radioactive waste site. Small quantities of bacteriological waste also are generated from the hospital and medical laboratories on site (ADEC and EPA 1990). ATSDR was unable to identify the location where this waste was disposed.
II.C. Remedial and Regulatory History
In August 1990, Fort Wainwright was placed on the National Priorities List (NPL) because of
contaminated areas on the installation. The NPL is a listing maintained by the U.S.
Environmental Protection Agency (EPA) 
in accordance with the provisions of the 1980
Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA, 42 USC
103), commonly known as "Superfund." The contaminated areas initially identified on the post
included (1) a 50-acre sanitary landfill used for hazardous waste disposal since the late 1940s; (2)
the North Post Family Housing Area contaminated from past storage of petroleum products,
solvents, and other chemicals; and (3) disposal of power plant ash and slag containing heavy
metals, such as chromium and mercury (EPA 2002). As a result of being placed on the NPL, the
Army was required to comply with the Army installation restoration program of the U.S.
Department of Defense (DOD). This restoration program calls for an investigation of current and
past waste disposal practices and the nature and extent of contamination at the installation under
IRP (Harding Lawson 1994a).
In March 1992, the U.S. Environmental Protection Agency (EPA), Alaska Department of Environmental Conservation (ADEC), and DOD entered into a Federal Facilities Agreement with Fort Wainwright to develop remedial action plans for environmental contamination at Fort Wainwright (ENSR 1996).
Also in March 1992, the Army and ADEC signed a Two-Party Agreement to define the process by which the Army agreed to investigate and clean up petroleum-contaminated areas. The Two-Party Agreement outlines the Army's commitment to investigate and clean up underground storage tank (UST) sites and surface petroleum contamination (ADEC and U.S. Army Alaska 1992). Petroleum-contaminated sites are not covered under CERCLA or the Federal Facilities Agreement; however, these sites are addressed under the Two-Party Agreement.
Fort Wainwright contains a number of potential sources of contamination (PSCs), where releases of contaminants to the soil might have migrated to the groundwater and, possibly, to surface water (Figure 2). Many of these sites are at varying stages of investigations. In addition to ongoing investigations, Fort Wainwright has implemented measures to reduce and/or control the spread of contamination. These actions include installing groundwater remediation systems (i.e., soil vapor extraction and air sparging (SVE/AS, controlled air injection into the soil to promote contaminant removal and degradation); removing contaminated soil; and locating and removing buried drums, refuse, and other potential contamination sources. By September 2002, remedial actions for the entire post were constructed, operational, and functional (U.S. Army Alaska 2002a; U.S. Army Fort Wainwright 2003). In addition, Ft Wainwright has directions in place that require all project managers and personnel planning any intrusive actions to notify the base Environmental Office of any planned on-base building or digging project. The Environmental Office will help the manager identify if the operational history or environmental data surrounding the proposed location indicates the potential for hazardous materials or environmental contamination. All project managers are also required to report to the Environmental Office any evidence of hazardous materials or environmental contamination (personal communication with Therese Deardorff, June 24, 2003).
As part of the public health assessment process, ATSDR conducted an initial site visit to the installation on July 22-23, 1991. The purpose of the trip was to meet with federal, state, and local environmental and public health officials, as well as concerned citizens, to obtain information to assist in preparing the PHA. ATSDR revisited Fort Wainwright in 1998 and 2001 to gather additional data to assist in its evaluation of public health hazards. During the 1998 visit ATSDR also met with some of the residents of the on-post and nearby off-post communities. Two concerns were identified and evaluated. One individual was concerned about possible exposure to harmful levels of contaminants in lawn-irrigation water drawn from the Shannon Park Baptist Church private well, which was known to contain VOC contamination, and a second citizen was concerned about learning disabilities among children at the post. ATSDR prepared a health consultation on the use of water from the Shannon Park Baptist Church private well for lawn irrigation, and found that no public health hazard existed from contact with this irrigation water (ATSDR 1999a). This public health assessment addresses the concerns in the community about contamination in the church wells and past use of the church wells for drinking water. ATSDR also evaluated concerns about learning disabilities and attention deficit disorders among children attending two schools serving military families at Fort Wainwright. ATSDR prepared a letter of technical assistance regarding learning disabilities and attention deficit disorders among children at these two schools. The results showed that children who attended the two schools did not suffer from a higher incidence of learning disabilities than children statewide (ATSDR 1999b).
During the site visits and following a preliminary review of the data, ATSDR did not find any health threats at Fort Wainwright that required immediate attention. ATSDR, however, noted several possible exposure situations that require further study. ATSDR prepared this public health assessment to further evaluate these exposures scenarios.
ATSDR examines demographic (population) information to identify the presence of sensitive populations, such as young children (aged 6 years or less), the elderly (aged 65 years or more), and women of child bearing age (aged 15 to 44 years). Demographic data also provide details on population mobility and the residential history in a particular area. This information helps ATSDR evaluate how long residents might have been exposed to environmental contaminants.
In June 1999, 4,421 dependents and 1,874 Army personnel lived in on-post housing (McBroom 1999). About 1,400 family housing units are on Fort Wainwright, including both officer grade and enlisted grade units. Post housing includes the 801 Housing Subdivision (also known as Birchwood), located in the western portion of the main cantonment area; and the North Post Housing Subdivision, located in the southwestern portion (EPA 2003). In addition, individual troop quarters can house approximately 300 officers and 3,100 enlisted men (Nakata Planning Group 1987). The post is situated within the Fairbanks city limits, a few miles east of the downtown area. The city of North Pole (population 1,619) is located southeast of the Main Post. The Tanana River separates the city and Fort Wainwright (Nakata Planning Group 1987). Residential subdivisions border the post boundaries to the west and north.
Fort Wainwright has several schools that serve both civilian and military students living on or near Fort Wainwright. These schools are the Auora, Chena, Fort Wainwright Junior High, and a new school that had not yet been named. The Birch School building is no longer used as a school. Two Fairbanks schools, the Ladd Elementary and Tanana Middle Schools, are located on leased land at the post. The installation has three child care centers that offer regular child care services during the week (Fort Wainwright 2001).
Approximately 83,000 persons live in the Fairbanks North Star Borough. The population of the city of Fairbanks is approximately 32,000. The Main Post of Fort Wainwright lies within the Fairbanks city limits, east of the downtown area. Two residential areas, Hamilton Acres and Island Homes, border the west side of the main post area. To the north, Fairweather Heights and Fairhill Subdivisions approach the installation boundary. The city of North Pole (population 900) is southeast of the Main Post.
ATSDR examines land use to determine activities that might put people at risk for exposure to contaminants related to Fort Wainwright. Fort Wainwright is divided into four noncontiguous areas, the Main Post, the Tanana Flats Training Area, the Yukon Maneuver Area, and a range complex. Public access is limited. The Main Post is partially fenced and has four access gates. The main gate is open 24 hours a day, two gates (Badger Road and Richardson Highway) are open for morning and evening rush hours, and the Trainer Road gate is used to accommodate the newer family housing units. (Due to security measures, gate access hours fluctuate.) The range complex lies between the Main Post and the Tanana Flats Training Area. Training and maneuver areas are designated as restricted use areas, but only some are fenced (Nakata Planning Group 1987). During the site visit in 2001, ATSDR observed the locations of posted restrictions.
Much of Fort Wainwright's land is open to hunting. Within the Tanana Flats Training Area alone, over 590,000 acres are visited by hunters. Only two areas are permanently closed to the public, the Alpha Impact Area and the Blair Lakes Bombing Range. Individuals, civilian or military, who wish to hunt at Fort Wainwright must obtain a permit and a map of areas of prohibited use (U.S. Army Alaska 2000a).
Fort Wainwright has many outdoor facilities for recreation, including the nine-hole Chena Bend golf course, the Birch Hill ski area, Glass Park on South Post and Engineer Park on North Post (both have picnic facilities), and Birch Lake, which offers military personnel water sports, camping grounds, and fishing (Harding Lawson 1992). The Chena River and Tanana River in the Fairbanks area also are used for recreational swimming, snowmachining, and fishing; however, swimming is quite limited because of the cold climate. People fish year-round in the Fairbanks area, including ice-fishing when the lakes and rivers have frozen over (Harding Lawson 1997). Surface water is not a source of drinking water for Fort Wainwright or for off-post residential areas in the vicinity of Fort Wainwright. Most potable drinking water comes from groundwater.
Natural resources used in the vicinity of Fort Wainwright include groundwater for drinking
water, surface water bodies for recreational uses, and hunting and fishing of local biota (e.g.,
plants and animals). Some key exposure concerns associated with Fort Wainwright concern
chemical contamination in the shallow aquifer (groundwater) and releases to the Chena River.
For information on how contaminants might migrate to and/or accumulate in these media,
ATSDR obtained background information on the local terrain and climate and on the
hydrogeology of local groundwater and surface water.
Fort Wainwright lies above a shallow groundwater aquifer,
the Tanana Basin Alluvium Aquifer. The alluvium, or loose
sediment largely consisting of sand and gravel, is
distributed over a broad area, providing a large water
storage capacity. The aquifer ranges in thickness from a few feet at the base of Birch Hill (in the
northern portion of the post) to at least 300 feet at the Main Post, and possibly as much as 700
feet in other areas of the Tanana River Valley. The depth to water is typically 10 to 20 feet.
Regional groundwater flow is to the west-northwest in the Fairbanks/Fort Wainwright area. The flow pattern at Fort Wainwright is similar to the Chena and Tanana Rivers (Harding Lawson 1996b). Groundwater flow beneath Fort Wainwright, south of the Chena River, is generally to the northwest. The flow is driven primarily by the difference in river stage between the Tanana and Chena Rivers. During most of the year, groundwater flows from the Tanana River toward the Chena River, flowing onto the base from the southern and eastern base boundaries, and exiting on the western border of the base. At some times of the year, however, the groundwater flow paths near the Chena River are essentially reversed. This occurs when the Chena River stage suddenly increases from the increased flow caused by precipitation and snow melt.
Groundwater flow in the area immediately north of the Chena River, from the north-central cantonment area of Fort Wainwright to Birch Hill, is typically toward the south-southwest. Regional groundwater flow data indicate that groundwater enters the base from the northern and eastern boundaries, and then flows toward the south/southwest. Research by Lawson et al. (1998) and McCauley (2000) suggests that local diversions from the regional groundwater flow pattern might be more common in areas north of the Chena River because of areas affected by permafrost (discussed below) and areas with buried bedrock gullies that extend from Birch Hill toward the Chena River. Groundwater flow north of the river does not cross the Chena River, but it exits through the western boundary of the base.
Groundwater flow varies from area to area within Fort Wainwright due to natural differences in the valley surface and subsurface soils. Zones of fine-grain sand and silt are intermingled with zones of coarser-grained sands. Fine-grained materials tend to retard groundwater flow, and the coarser materials are more permeable and typically allow greater amounts of groundwater flow.
II.G.2. Surface Water Hydrology
Fort Wainwright lies entirely within the Tanana River drainage basin. The Tanana River, a major tributary of the Yukon River, flows east to west, approximately 3 miles south of the Fort Wainwright main cantonment area, encircling the northern and eastern boundaries of the Tanana Flats Training Area.
Fort Wainwright also lies within the flood plain of the Chena River, a tributary of the Tanana River. The Chena River drains an area of approximately 2,000 square miles. It meanders westward through the Main Post, forming several oxbows, then flows into the Tanana River approximately 8 miles west-southwest of Fort Wainwright (Harding Lawson 1997). The Chena River is an influent system for most of the year: when the river is at normal and low stages, groundwater is flowing into the river. During high stages, when the melting snow and ice combine with rainfall, the surface water discharges into the groundwater. In August 1967, the Chena River overflowed after 6 days of continuous rain, causing the worst flood in Fairbanks' recorded history. According to the Army Corp of Engineers, the banks of the Chena River have a capacity of 12,000 cubic feet of water per second (cfs). The maximum recorded flow during the flood was 74,480 cfs. The river crested near the 19-foot level (about 7 feet above flood stage), leaving all of Fairbanks, and much of the surrounding area, under water. Notable damage in Fairbanks included clogged sanitary sewers; collapsed sewer cess pools; siltation of personal property; pollution of potable well water; and degredation, failure, and/or implosion of building foundations and basement walls (Alaska State Housing Authority 1996; Gruening 1967).
Many creeks and smaller rivers located on Fort Wainwright eventually flow into the Chena or Tanana Rivers. The post also has a number of lakes, including Birch Lake, Harding Lake, and Blair Lake. Birch Lake, located approximately 60 miles southeast of the main cantonment areas, is used for fishing and other recreational purposes during the warm season. Another on-post lake, Monterey Lake, is located in the main cantonment area, but it is a flooded borrow pit (a pit that remains after dirt has been "borrowed" from that area) and the lake is not used for recreation.
Fort Wainwright is located in two different topographical areas, the Tanana-Kuskokwim Lowlands and the Yukon-Tanana Uplands of Central Alaska. The Main Post is primarily located on relatively flat terrain, with a typical elevation about 450 feet above mean sea level. The northern portion of the Main Post has higher terrain, with elevations rising to above 1,000 feet above mean sea level (Ecology and Environment 1993). The climate in the central part of Alaska is characterized by summer temperatures that range from 65 to 90 degrees (Wainwright 2003).
Fort Wainwright and Fairbanks are in the Central Alaskan region of discontinuous
permafrost (see text box). Discontinuous permafrost refers
to a region in which some areas are underlain by permafrost and neighboring
areas are not perennially frozen. The unfrozen zones can be isolated or interconnected
(USGS 1999). Groundwater investigations carried out by USACE in the north-central
area of the main cantonment area of the base confirm that permafrost does exist
beneath Fort Wainwright; however, the extent and thickness of the permafrost
varies greatly across the north-central cantonment area (Lawson 1998). In the
Fairbanks vicinity, the uppermost portion of permafrost (the permafrost table)
varies from 1.6 to 65 feet (0.5 to 20 meters [m]) below ground surface. The
base of the permafrost commonly ranges from 3.2 to 164 feet (10 to 50 m) below
the ground's surface (Ferrians 1965, Williams 1970, Lawson 1998).
Permafrost (and seasonally frozen soil) can make it more difficult for rainwater and snow melt to infiltrate to deeper groundwater zones. Even so, unfrozen water will still pass through porous permafrost. Permafrost also can alter groundwater flow patterns, causing erratic and unpredictable movement. Groundwater in areas of permafrost, such as north of Chena River at Fort Wainwright, is most likely to occur in (1) the active layer during the summer (frost-free) season; (2) in taliks (unfrozen zones) within the permafrost; and (3) in unfrozen zones below the permafrost layer. (See Appendix A for detailed information on permafrost.)
Fish in the Chena River. Fishing is the major recreational use of the Fairbanks area rivers. The following are all supported by both rivers: three species of salmon (king, silver, and chum), arctic grayling, burbot, humpback whitefish, sheefish, lake chub, least cisco, northern pike, longnose sucker, slimy sculpin, round whitefish, and arctic lamprey.
Game. Big game animals hunted in the Fort Wainwright area are brown/grizzly bear, black bear, moose, wolf, and wolverine. Occasionally, a caribou wanders onto the Tanana Flats Training Area. Fur animals sought after by hunters and trappers include squirrel, red fox, lynx, and coyote. Small game available are grouse, ptarmigan, hare, and waterfowl (Eielson 2003).
II.H. Quality Assurance and Quality Control
In preparing this public health assessment, ATSDR reviewed and evaluated information provided in the referenced documents. Documents prepared for the CERCLA program must meet standards for quality assurance and control measures for chain-of-custody, laboratory procedures, and data reporting. The environmental data presented in this public health assessment report were provided by Fort Wainwright, EPA, and ADEC. Based on its evaluation, ATSDR determined that the quality of environmental data available in post-related documents for Fort Wainwright is adequate for making public health decisions.
III. SOURCES OF ENVIRONMENTAL CONTAMINATION
Routine operations and waste disposal practices in the past have resulted in accidental spills and releases to the ground surface at various locations at Fort Wainwright. Some examples of these activities include refueling and maintenance of vehicles and aircraft and using fuel in fire-training exercises, landfill operations, and treatment of coal at the coal storage area. Common contaminants released as a result of these former activities are fuel components and cleaning solvents. Following a releases to the ground, a portion of these contaminants is carried in rain water and snow melt that seeps through the soil and, eventually, flows into underlying groundwater and, possibly, the Chena River.
In the discussion that follows, ATSDR describes source areas of contamination at Fort Wainwright and provides information about the source areas that specifically affect groundwater resources, soil, surface water/sediment, and/or ambient air. Table 1 summarizes the types of contaminants found at each source area at Fort Wainwright.
Potential sources of contamination (PSCs) at Fort Wainwright have been divided into five operable units (OUs), OU1-OU5. PSCs were grouped together into OUs on the basis of type of site, potential threat to groundwater from source-area contamination, and effort level required to complete a remedial investigation (RI). Clean-up measures are underway at all OUs and this work will continue until clean-up goals are achieved. Table 2 lists each of the PSCs and the recommended remedial action. Each of the PSC sites is described in greater detail in Table 3 (U.S. Army Alaska 1996a, 1996b, 1997a, 1997b, 1999).
Some of the source areas at Fort Wainwright involve only petroleum-related contamination, which is not monitored by EPA under the Federal Facilities Agreement. These sites are being addressed through the Two-Party Agreement, specifically for sites with petroleum contamination. At the time this PHA was conducted, 13 sites are being followed as part of the State-Army Two Party Agreement (U.S. Army Alaska 2002a; U.S. Army Fort Wainwright 2003).
Three of these sites have active treatment systems in place: Building 2250, Buildings 2111/2112, and Building 2077. However, the Army is currently exploring options to improve the treatment performance of the system in place at Buildings 2111/2112 (U.S. Army Alaska 2002a). The other sites either do not require groundwater treatment or have a SVE/AS system treatment with follow-up through ongoing groundwater monitoring. Groundwater monitoring results indicate that the level of contaminants at these sites are either decreasing or not migrating.
III.B.3.Other Source Areas and Physical Hazards
Several other areas or operations have been suspected of or associated with releases of pollutants to the environment or posing physical hazards.
III.C. Contaminant Sources, by Media
In this section, ATSDR presents an overview of contaminates carried via environmental media (e.g., air, soil, water). In reviewing the environmental data ATSDR selects contaminants for further evaluation by comparing the measured concentration of the contaminant to its health-based comparison value (CV). A CV is the concentration level of a specific chemical that health scientists have determined are not likely to cause adverse health effects. CVs are developed by ATSDR from scientific literature available on exposure and health effects. These CVs are derived for most contaminants and are specific for each of the environmental media. They reflect an estimated concentration for a given chemical that is not expected to cause adverse health effects, assuming a standard body weight and a standard daily contact rate (e.g., amount of water or soil consumed or amount of air breathed). Because CVs are not thresholds of toxicity, environmental levels that exceed CVs would not necessarily produce adverse health effects. By design, CV are very conservative values and are frequently lower than the regulatory standards for a given contaminant. Their conservative nature ensures that ATSDR will identify all contaminants in an environmental media that could possibly cause a health concern. If a chemical is found in the environment at levels exceeding its corresponding CV, ATSDR closely examines the potential exposure variables and toxicology of the contaminant to identify the types of adverse health effects that could be expected to result from that exposure.
III.C.1. Contaminant Sources that Affect Groundwater Resources
The Army established a groundwater monitoring program in the mid-1980s as part of the Installation Restoration Plan (IRP) to identify, investigate, and clean up contaminants in groundwater from former site releases. These investigations have identified primarily volatile organic compounds (VOCs) in the shallow aquifer beneath Fort Wainwright, and to a lesser extent, metals and pesticides. High levels of contaminants were found at sites located south of the Chena River, including the Coal Storage Yard, DRMO yard, the West and East QFS, and the Railroad Off-Loading Facility. Some of the releases were found at operations areas or landfills north of the Chena River, including the Birch Hill Tank Farm, Building 1168, Fort Wainwright Sanitary Landfill, and FEP. The Army is pursuing clean-up measures at several of these sites to reduce contamination levels. The following discussion describes important features of these areas, such as type and concentrations of contaminants in the groundwater and the history of Army and regulatory agencies' efforts to address remedial actions for contamination of groundwater.
Source Areas South of the Chena River
Coal Storage Yard (OU4): The Coal Plant Storage Yard, located west of Meridian Road, supplies coal to the post's power plant. The yard contains an active coal pile stored directly on the ground and an auxiliary pile for use when the active pile is depleted. Before 1993, coal stored in the yard was sprayed with waste oils, solvents, and fuel to increase the heating capacity of the coal. This practice contaminated the groundwater underneath the Coal Storage Yard (Fort Wainwright 1995). In 1994, monitoring revealed the groundwater beneath the storage yard contained high levels of VOCs. Maximum concentrations of VOCs and other organic compounds detected at levels above their CVs since 1994 are TCE (56 ppb), benzene (3 ppb), chloroform (10 ppb), bis(2-ethylhexyl) phthalate (110 ppb), dieldrin (0.03 ppb), and heptachlor (0.08 ppb). One metal, arsenic, was detected above its CV (12 ppb) (Ecology and Environment 1995). Groundwater flows northwest from the coal pile. The contaminants migrated in a plume that was limited to the area under the active coal pile and extending to the fenced storage yard. No contamination was found in downgradient wells (Ecology and Environment 1997). Contaminant migration from the active coal piles does not appear to extend beyond the storage yard.
Remedial measures taken to prevent the spread of groundwater contamination include installation of SVE/AS systems for groundwater treatment, which began in August 1997, and groundwater monitoring to determine if expansion of the AS is necessary to prevent contaminant migration (U.S. Army Alaska 1998a). Sampling conducted in 1998, showed that TCE concentrations declined from 56 parts per billion (ppb) in 1994 to 6 ppb in April 1998. TCE was not detected during sampling conducted in October 1998 (DOWL/Ogden 1999a).
The Defense Reutilization and Marketing Office (DRMO) Sub-Areas (OU 2)
Located on the east boundary of Fort Wainwright, the DRMO is a fenced area of 25 acres. The Army used the area as a vehicle storage area and maintenance shop, beginning in the 1940s. In 1961, it was converted to the DRMO, the post's salvage yard and hazardous material transfer point. This site is still an active DRMO facility; a transfer point for equipment and hazardous material. Obsolete, surplus, and unserviceable equipment is stored here until it is transferred to another post, sold at auction, or destroyed.
Hazardous materials stored in the area included waste oil, pesticides, solvents, vehicle fluids, and electrical transformers (some containing PCBs). Many drums containing these material reportedly leaked. Residents in three nearby subdivisions use the groundwater as a drinking water source. Private wells in the residential area are located in the same aquifer as the DRMO Salvage Yard contamination. Groundwater flows west to northwest, and away from these residences.
The area has been subdivided into six subareas (DRMO1-DRMO6). DRMO-1 contains PCE and TCE at levels above the MCL of 5 ppb. A well-defined groundwater plume, with levels up to 190 ppb and 17 ppb for PCE and TCE, respectively, has been identified. PCE has migrated to the northwest and extends beyond the DRMO salvage yard's boundary. PCE-saturated soils, which appear to be the source of groundwater contamination, are being treated. A plume of TCE in groundwater has migrated from DRMO-4 to the west-northwest to the central part of the DRMO site. This plume is not moving off site or in a direction that threatens either off-site wells or the post's drinking water supply wells (Harding Lawson 1993a). The other DRMO subareas, DRMO-2, DRMO-3, and DRMO-5, contained constituents from petroleum and fuel products from buried underground storage tanks that have not been removed.
Groundwater remediation systems, including SVE/AS, have been in place at the DRMO Yard since 1997 and will continue until VOC contaminants in groundwater are reduced to their respective EPA-established maximum contaminant levels (MCLs) (U.S. Army Alaska 1997b, U.S. Army Alaska 2002b). MCLs are enforceable drinking water regulations developed by EPA to protect public health. DRMO-2, DRM0-3, and DRMO-5 did not contain VOCs in groundwater above CVs and are being remediated under the State-Army Two-Party Agreement. Groundwater wells (and nearby drinking water wells) also are monitored as part of a long-term monitoring program. More recent sampling in 1998 and 1999 showed decreased levels of VOCs, including benzene (1.31 ppb) and TCE (3.08 ppb). PCE was not detected in the DRMO-4 subarea in April 1999 (HartCrowser 1999a). No migration of VOC contamination has been detected moving toward Channel B (i.e., away from the site). Periodic groundwater sampling is conducted to evaluate the effectiveness of treatment systems. The Army also is currently considering expanding the on-site treatment systems at the DRMO-1 and DRMO-5. Analytical results indicate that the treatment systems currently in place at these subareas do not adequately address the diesel range organic contamination. The systems appear to be too small (U.S. Alaska Army 2002a).
East and West Sections of the Quartermaster Fueling Systems (OU 5): The East and West Sections of the Quartermaster Fueling Systems (QFS) are located along the southern bank of the Chena River.
None of the plumes associated with the QFS are moving off site or in a direction that threatens either off-site wells or post drinking water wells. The plumes, however, are moving in the direction of the Chena River, prompting efforts to prevent contaminants from reaching the river. Groundwater remediation, including SVE/AS, was initiated in the mid-1990s to treat the contamination and will continue until contaminants in groundwater are reduced to their respective MCLs. In 1997, horizontal air sparging wells were installed in the West QFS area. In 1998, an air sparge "curtain" (a line of air sparging wells) was installed between the contaminant plume in West QFS and the Chena River to prevent any further contaminants from reaching the river (U.S. Army Alaska 1999). The Army enhanced the AS treatment system by adding more wells along the Chena River in 2001, after monitoring results indicated that the groundwater contamination was still moving toward the river (U.S. Army Alaska 2001b, 2001c). The Army continues to monitor groundwater in the QFS on a quarterly basis (U.S. Army Alaska 2002b).
Railroad Off-Loading Facility (ROLF) (OU 3): The ROLF was built in 1939, to receive fuel from railcars. It was located across from the Tank Farm Facility, on the other side of the Chena River, and pipes connected the two facilities. The facility is no longer used. While operational, petroleum leaks resulting in petroleum contamination of groundwater occurred at Valve Pits B and C along Front Street, and at the center of OU 3. Groundwater beneath areas of the ROLF contained VOCs (benzene [to 5,800 ppb], toluene [to 4,700 ppb], and 1,2-DCA [to 6 ppb]) at levels exceeding their respective ATSDR Cvs. These contaminants do not threaten any off-site on on-site drinking water wells.
Treatment began in 1996, with SVE/AS and was expanded in 1997 (U.S. Army Alaska-June 1998). Groundwater monitoring results indicated the groundwater contaminant levels are being reduced at the Eight-Car Header, Former Building 1144, Central Header, and Valve Pits A, B, and C at the ROLFs (U.S. Army Alaska 2001c). Samples collected from the majority of the areas indicate contaminant levels are below MCLs. The SVE system in those areas will no longer be in operation (U.S. Army Alaska 2002c).
Source Areas North of the Chena River
Birch Hill Tank Farm (OU 3): The Birch Hill Tank Farm, located north of the main cantonment area, housed fuel tanks that were used to store fuel for Fort Wainwright and Eielson Air Force Base. Fuels stored at the site included arctic-grade diesel fuel, aviation-grade leaded gasoline, aircraft turbine and jet engine fuel (JP-4), leaded vehicle motor gasoline, and unleaded and regular motor fuel (EPA 2003). Monitoring during the 1994 RI indicated that groundwater beneath the tank-farm area contained the following VOCs: 1,2,4-trimethylbenzene (1,400 ppb), 1,3,5-trimethylbenzene (1,700 ppb), benzene (1,700 ppb), ethylbenzene (1,600 ppb), toluene (12,000 ppb), xylenes (6,400 ppb) and 1,2-dichloroethane (DCA) (8.6 ppb) (Ecology and Environment 1994). Lead was detected at levels of 300 ppb (EPA's Action Level for drinking water systems is 15 ppb).
Between August 1992 and June 1997, 15 groundwater samples were collected from a deep monitoring well (AP-5782) and from a shallow monitoring well (AP-5783). Both wells are located along the post's western boundary. The samples were analyzed for post-related VOCs and the results showed that 1,2-DCA and/or benzene were present in about a third of the samples collected from the deep well. Some of the detections exceeded ATSDR's CVs and EPA's MCLs. Three shallow well samples contained lower concentrations of 1,2-DCA at levels above ATSDR's CVs but below EPA's MCLs.
In June 1997, U.S. Geological Survey (USGS) sampled three monitoring wells located approximately ¼ mile from the Birch Hill Tank Farm. These wells are located along the east edge of the alley that borders the Steese Chapel Hall and Shannon Park Baptist Church properties, between the post boundary and the church buildings. No contaminants were detected in the USGS wells at levels above ATSDR's screening CVs (HartCrowser 1998b).
Sampling of the church's "deep" drinking water wells started in 1991. Analyses indicated the presence of 1,2-DCA. After the initial detection of contamination, the church wells were no longer used for drinking water. The sampling results for the church wells and potential exposure to contamination via this drinking water are discussed further in the "Evaluation of Exposure Pathway" section of this public health assessment report.
The Army has operated a product recovery system since 2000 that consists of 12 extraction wells, a dual-phase pump, and an oil-water separator that removes the petroleum free-product from the groundwater. An additional AS treatment system at the tank farm became operational in January 2001. The system, which operates year-round within a heated building, is intended to reduce groundwater contamination before it migrates beyond post boundaries. Since operations began, the Army made some modifications to counter the effects of a buildup of iron in the carbon filters and periodic reductions in product recovery. Currently, about 8 gallons of product are removed each day, then stored in drums at the Tank Farm until it is collected by the Army's hazardous waste disposal unit. The Army is continuing to monitor groundwater at the Shannon Park Baptist Church, a private property near the Tank Farm (U.S. Army Alaska 2001a, 2001b, 2002a).
Fort Wainwright Sanitary Landfill (OU 4): This site has served as a landfill since the 1950s. Sampling from 20 monitoring wells in 1993, and 17 monitoring wells in 1994, revealed high levels of VOC contaminants in the groundwater beneath this site. VOCs and other organic compounds detected above their CVs include the following: 1,2- DCA (5.1 ppb), 1,1,2,2-tetrachloroethane (1,300 ppb), 1,1,2-trichloroethane (8.1 ppb), benzene (4.4 ppb), bis (2-ethylhexyl) phthalate (620 ppb), bromodichloromethane (2.9 ppb), chloroform (33 ppb), cis-1,2-dichloroethene (470 ppb), total 1,2-dichloroethene (130 ppb), trichloroethylene (TCE) (170 ppb), and tetrachloroethylene (PCE) (91 ppb). Four metals were detected above their CVs, arsenic (110 ppb), iron (100,000 ppb), lead (23 ppb), and manganese (5,800 ppb) (Ecology and Environment 1995). In June 1997, the following contaminants were detected in groundwater samples (some at levels equal to or higher than those detected in 1993 and 1994): benzene (4.01 ppb), 1,2-DCA (5.06 ppb), 1,1,2,2-tetrachloroethane (1,920 ppb), 1,1,2-trichloroethane (9.92 ppb), cis-1,2-dichloroethylene (DCE) (184 ppb), TCE <(243 ppb), and arsenic (63.3 ppb) (DOWL/Ogden 1999b).
Fourteen acres of an inactive portion of the landfill was capped in September 1997, with an impermeable layer to prevent more contaminants from leaching into the groundwater at the landfill (Ecology and Environment 1997). Closure of the active portion of the landfill will occur after the landfill is full (Siftar, 2003b, personal communication). The groundwater beneath the landfill is sampled twice a year as part of the Army's long-term sampling program (U.S. Army Alaska 2000b, 20001a, 2002a, 2002b). No significant changes in the levels of contaminants in the groundwater were detected since the cap was installed in September 1997 (U.S. Army Alaska 2002b). The underlying groundwater has measurable levels of various VOCs including concentrations of DCE and TCE that range from two to fifty times greater than their respective MCLs. However, this contaminant source does not affect any drinking water wells, and it and is unlikely to affect water quality of the Chena River.
Building 1168 Leach Well (OU 2): Building 1168 was created as a vehicle and lube oil storage area in 1949, and converted into a petroleum test laboratory in 1962. The building is on Trainer Gate Road, north of the 801 Building Area. The building formerly contained a 10,000-gallon lube oil AST, an oil/water separator system, and a 250-gallon UST that discharged to a leach well. The following products are suspected to have entered the leach well: engine and transmission oil, gasoline, diesel fuel, jet fuel, solvents, hydraulic fluid, and engine coolants.
Contamination was found in a well-defined plume downgradient of the leach well. Sampling data indicated the plume consisted primarily of PCE and benzene. The groundwater also contained VOCs, including petroleum hydrocarbons, and metals (arsenic [27 ppb]) and manganese [4,400 ppb]) above CVs (Harding Lawson 1996a).
Two civilian residential subdivisions are located adjacent to Fort Wainwright's western boundary, and one military housing area is directly south of the source area and Trainor Gate Road. Groundwater flows from the leach well toward these residences. Most residences are serviced by the Fairbanks municipal water system, although some still use private wells for drinking water. Tanana Junior High School and Ladd Elementary School are 300 feet and 600 feet northwest, respectively, of the source area, but both are on municipal water (E&E 1997).
The SVE/AS system was operated at Building 1168 from 1995 through 1998 and successfully decreased contaminants levels below action levels. The system now operates in a passive mode. The Army conducts annual groundwater monitoring (U.S. Army Alaska October 1999). Sampling in March 2000 indicated benzene and DRO at concentrations above action levels. Additional sampling conducted in September 2000, showed benzene at levels (3.4 ppb) below the ADEC action level (MCL) of 5 ppb (U.S. Army Alaska October 2000; January 2001). Downgradient sentry wells monitor whether benzene is migrating toward the post boundary. Overall, the concentrations detected during routine monitoring have been declining since the SVE/AS remediation was implemented in 1995. No VOCs appear to be moving off site; contaminants have not been detected in downgradient sentry wells through 2000 (HartCrowser 1999b, U.S. Army Alaska 2001c). Contaminants in the groundwater do not threaten off-post residential water wells or on-post residential homes.
Fairbanks-Eielson Pipeline (FEP) (OU 3): The pipeline at Milepost 15.75 ruptured on August 26, 1989. It is estimated that more than 4,200 gallons of fuel were spilled. Approximately half of this spilled fuel was recovered within 2 hours of the rupture. The ruptured portion of the pipeline is located in an off-post residential area at the intersection of Laurance Road and Robyn Drive. Residential wells exist approximately 200 feet from this source area. Petroleum contamination was found in soils within 100 feet northwest of the spill location. Some of the petroleum contamination had leached down through to the area's shallow aquifer. Monitoring wells were installed between the location of the spill and the residential properties. Two VOCs, benzene (34 ppb) and 1,2-DCA (8 ppb), were detected above their CVs in the groundwater monitoring wells. Groundwater remediation by SVE/AS was conducted in 1996 and 1997 (HartCrowser 1997a). Quarterly groundwater monitoring suggests that contaminants are not migrating toward the residential wells.
Two other sites along the pipeline, Milepost 2.7 and Milepost 3.0, have had contaminants identified in the groundwater beneath them. Both sites are located within a military training area in the northeast portion of the main cantonment area, about 1 mile from the northern bank of the Chena River. Sparse residential property exists to the northeast of these sites (EPA 2003). During the 1970s, the pipeline ruptured at Milepost 2.7, releasing contaminants that leached into the underlying groundwater. Groundwater contamination was found at a depth of approximately 2 feet below the ground surface. The following petroleum fuel constituents were detected in the groundwater at Milepost 2.7 at levels above their respective CVs: 1,2,4-trimethylbenzene (240 ppb), 1,3,5-trimethylbenzene (320 ppb), benzene (140 ppb), and toluene (700 ppb). Milepost 3.0 does not have any recorded ruptures or releases, and contamination there could be from Milepost 2.7, or from the nearby Birch Hill Tank Farm. The following VOCs were detected at Milepost 3.0 at levels that were above their CVs: benzene (7,200 ppb), ethylbenzene (1,100 ppb), and toluene (2,300 ppb) (U.S. Army Alaska 1996b). The areal extent of the groundwater contamination is not defined for either source.
Groundwater generally flows southwest across Milepost 2.7 and 3.0. According to information in the ROD for OU 3, the closest drinking water wells to Milepost 2.7 and 3.0 are located 1 mile and 1.25 miles west, respectively, at the Birch Hill Ski Area. The Birch Hill Ski Area well draws water from the Birch Creek Schists Aquifer, which is not directly connected to the alluvial aquifer affected contamination from Milepost 2.7 or 3.0. The Army is using SVE/AS systems at Milepost 2.7 and 3.0 to treat areas of petroleum contamination. Once soil cleanup goals are met, the Army will install new wells to monitor groundwater quality to ensure that the full extent of contamination has been defined and addressed (U.S. Army Alaska 2002c).
III.C.2.Contaminant Sources that Affect Surface Water Resources
The Chena River flows east to west through the northern portion of the Main Post. Both on- and off-post, the river is used predominantly for recreation activities and fishing. The Chena River is not used to supply drinking water for the on- or off-post communities; drinking water is provided from groundwater resources.
The Chena River is the primary receiving body for many of the contaminated source areas at Fort Wainwright. The 801 Drum Burial Site, the North Post Site, ROLF, two Tar Sites, and the East and West Sections of the Quartermaster Fueling Systems (QFS) are all located along the Chena River. In 1980, the Army discovered fuel seeping into the Chena River, north of the main cantonment in the area now part of West Section of the QFS area. At the time, the Army recovered as much free product as possible, and built a retaining wall to block further migration of contaminants into the river. This sheet metal retaining structure was removed in 1998, and replaced with an AS curtain. A seepage face, covering approximately 100 feet of river bank, remained. The Army placed a boom structure in the water around the seepage face to absorb free product that leaked onto the river's surface (ABR and CH2M Hill 1999).
Surface water from the Chena River was sampled during July and October 1994, September 1995, September 1998, and May and June 1999. All samples were analyzed for VOCs and SVOCs; samples collected in 1995 also were analyzed for metals. In 1994, the benzene (1.3 ppb) was detected in 1 of every 10 samples at levels above its CV (Harding Lawson 1995b). Benzene was the only chemical detected during the 1994 sampling event at levels above its CV. In 1995, the metals arsenic (4,400 ppb), lead (69 ppb), and selenium (86 ppb) were detected in the Chena River at levels exceeding the ATSDR drinking water CVs (Harding Lawson 1996b). The reported arsenic concentration is higher than the levels reported for other Alaskan streams; up to 9 ppb in filtered samples and 24 ppb in unfiltered samples (Meyer et al 2002; USGS 2001). Background measurements for the other metals were not described. The chemical bis(2-ethylhexyl)phthalate (4.5 ppb) was detected at a level slightly above its CV in 1995. VOCs or SVOCs were not detected above CVs in 1998 or 1999 (tests for metals were not conducted) (CH2M Hill 1999).
Sediment samples were collected from the WQFS and EQFS areas during the North Airfield Investigation in July and October 1994, during the OU 5 RI in 1995, and during the Chena River Aquatic Assessment in 1997 and 1998. Samples were analyzed for fuel components, associated VOCs and SVOCs, and pesticides. Selected samples also were analyzed for metals. Diesel and gasoline constituents were detected in sediment collected in 1995. All constituents were below their CVs. Low levels of SVOCs and pesticides were detected in sediment samples collected in 1997 and 1998, but no constituents were detected above their CVs (ABR and CH2M Hill 1999; Harding Lawson 1995b, 1996b). Metals also were found in the samples collected in 1995, including arsenic (to 9.5 ppm) and lead (to 450 ppm). The highest concentration of metals was generally found in the EQFS area.
During the Summer of 2000, the Army investigated how quickly and to what extent PAHs were entering the Chena River, particularly in the seep areas around the air sparing curtain (U.S. Army Alaska 2001a). PAHs were found to be released from the seep area into the river, primarily when the sediments were disturbed. High levels of PAHs were not observed outside of the seep area. The impact of PAHs and other site contaminants entering the river was further studied by the Army during an assessment of the Chena River in 2002. The Army collected and analyzed surface water and sediment samples for site-related chemicals and for the effects of site-related pollutants on river insect and larvae populations (U.S. Army Alaska 2001c). The study results are expected to help to determine whether (1) any detrimental effects have occurred to the river environment from off-post areas, and (2) whether the treatment systems are effective in reducing/ preventing site contamination from reaching the river (U.S. Army Alaska 2002a).
On the basis of the surface water and sediment sampling data reviewed for the Chena River, no evidence was found of chronic contamination from Fort Wainwright or from upstream releases of VOCs or SVOCs. VOCs and SVOCs have been sporadically detected in river water samples at concentrations above ATSDRs CV but typically below EPA's regulatory limits for drinking water. Sufficient sampling for metals has not been reported to identify if the metal concentrations detected in the 1995 sampling event are representative of a transient event or chronic contamination, or if the metal concentrations were affected by Fort Wainwright or upstream sources. If additional surface water and/or sediment sampling is conducted in the future, it would be prudent to include an analysis of metals to confirm or deny the concentrations measured in the 1995 sampling event. Additional sampling would help determine if the previous measurement was a spurious occurrence or if metal concentrations in the Chena River water are consistently above regulatory standards.
III.C.3.Contaminant Sources that Affect Surface Soil
Surface soil samples were collected and analyzed as part of the environmental investigations for most of the sites to characterize the type and extent of contamination. A number of sites have had contaminated soil excavated to remove the source of groundwater contamination and to prevent hazardous soil exposure, or the sites have been fitted with a soil-vapor-extraction system to reduce the contamination in soil.
A few contaminants were detected at Fort Wainwright above ATSDR CVs for soil. In the main cantonment area, the sites that have contaminants detected above the CVs are mainly in heavily industrialized areas, such as near the airfield. For example, POLs, metals, and/or solvents were measured in high levels in soil at the Birch Hill Tank Farm Facility and the Coal Storage Area; pesticides were found in soils at the 801 Drum Burial area and near Building 1567 (of OU1) and the DRMO area (in OU2); and fuel-related constituents from fuel leaks and spills were found at the East and West Sections of the QFS. Fuel-related compounds also have been reported in soil from spills occurring along sections of the FEP. Table 3 summarizes the type and extent of surface soil contamination and current remedial actions. Note that the discussion focuses on contaminants in surface soil. People are likely to come in contact with contaminants in the first few inches of soil; subsurface soil on the post is generally not accessed by the public.
Fort Wainwright was placed on the NPL, in part, due to concerns about contamination in the 45-acre North Post site that was proposed for housing. While conducting geotechnical investigations in 1985 for construction of a 150-unit housing development at the North Post site, workers reported strong petroleum odors in soil borings that they had collected. Further investigations and a risk assessment in 1986 and 1987, found some contamination along the western and southern boundaries of the North Post site. The source of the contamination is believed to be fuel spills from a former pipeline that ran from the Birch Hill UST Tank Farm until the 1960s. Other areas of the North Post site were free of contamination and considered suitable for housing (Harding and Lawson 1996a). In 1987, 58 housing units were built on the 17 acres along the eastern side of the oxbow, and away from the areas of petroleum contamination. The Army addressed the areas of soil contamination at the North Post site in 1993 and 1996 ( Harding Lawson 1996a, U.S. Army Alaska 1996a).
III.C.4.Contaminant Sources that Affect the Ambient Air
Air quality on Fort Wainwright is affected by a variety of factors, including on-post emission sources and local weather conditions. Several operations at Fort Wainwright have possible releases or documented releases to ambient air. Two significant sources are the coal-fired power plant and VOC emissions from the SVE/AS remediation systems. Atmospheric temperature inversions can exacerbate the effect of these emissions by trapping contaminants near the earth's surface, thereby preventing dispersion. Temperature inversions are common in the Alaskan interior during the winter, and the inversions are often coupled with low wind speed. The combination of a temperature inversion and low wind speed can prevent air pollutants from being dispersed at ground level or carried up into the air. Under these conditions, local ambient air concentrations of contaminants could be higher or lower than those measured at the regional air monitoring location.
The Fort Wainwright coal-fired power plant supplies heat and electricity for the post and burns approximately 300 tons of coal per day during the summer and up to 1,200 tons of coal per day in the winter. ADEC issued notices to Fort Wainwright in 1994 and 1996 for air pollution violations (EPA 1999). EPA issued a Notice of Clean Air Act Violation to the coal-fired power plant on March 10, 1999, because the plant was operating without functioning monitors and without adequate emission controls (EPA 1999). From the 1960s to 1993, coal used at the plant was sprayed with waste petroleum fuel products before it was burned, to improve the energy output of the power plant (EPA 1996).
Beginning in 1994, the Army began operating SVE/AS systems on post as part of the soil and groundwater remediation efforts. Many of the SVE/AS systems came on line in 1997. Much of the contaminants removed by these systems is in gas form. When originally installed, these systems were not equipped to capture all the volatilized chemicals. As a result, Fort Wainwright emitted 54 tons of VOCs in 1997, exceeding its permitted levels (40 tons) of VOC emissions (CH2M Hill 1998a). Emission controls were installed on the SVE/AS systems, bringing VOC emissions back into compliance. Fort Wainwright released 15 tons of VOCs in 1999 (ENSR 2000).
No monitoring data of on-post air or ambient air have been identified for Fort Wainwright. Ambient air monitoring information for carbon monoxide and particulate matter for the city of Fairbanks, west of the post, was available from the EPA Air Data database for the years 1996 through 2001. The measured ambient air concentrations at the nearest station (located 1 mile west of the base) never exceeded the 1-hour EPA Air Quality Standard for carbon monoxide, and exceeded the 8-hour standard only 4 times in 6 years. In the same 6 years, particulate matter never exceeded the EPA 24-hour-average Air Quality Standard or the annual mean air quality standard (EPA 2002). The average wind direction in Fairbanks is southwesterly during the summer (June-August) and northerly during the rest of the year (CH2M Hill 1994).
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