PUBLIC HEALTH ASSESSMENT
ANNISTON ARMY DEPOT
The Agency for Toxic Substances and Disease Registry (ATSDR) evaluated available environmental data and exposure information associated with the Anniston Army Depot (ANAD) and concludes that the ANAD site poses no apparent public health hazards, but that additional efforts are needed to more fully characterize the path and extent of groundwater contamination migrating from the ANAD site.
ANAD is an active facility occupying 15,200 acres in Calhoun County, Alabama. The depot was built as an ammunition storage facility in the early 1940s; however, ANAD's mission was expanded during World War II to include combat equipment storage and tank rebuilding. The southeast industrial area of the ANAD site was placed on the National Priorities List in 1989 because waste from the facility's industrial processes had contaminated groundwater and on-site soil. The primary contaminants detected in environmental media at ANAD are metals, chlorinated organic solvents, and explosive compounds.
ATSDR prepared a preliminary public health assessment for the ANAD site in 1989 and conducted site visits in 1991 and 1994. At the time of the 1994 site visit, definitive data on several potential exposure pathways did not exist. ATSDR identified the potential exposure pathway of principal concern as consumption of trichloroethylene (TCE)-contaminated groundwater. Of lesser concern are potential exposure pathways associated with on-site soil and with surface water and sediment contamination in Dry Creek, a small creek that forms the southeastern border of ANAD.
Since ATSDR's 1994 site visit, ANAD has conducted additional environmental investigations. Using data from these efforts, ATSDR has now completed a more thorough assessment of potential exposure pathways at the site. ATSDR did not identify any public health hazards associated with on-site soil or with recreational use of Dry Creek. The areas are either: (1) not widely used or accessible to the public, or (2) contamination was detected only at low levels, or (3) the contamination has been removed from the site.
Groundwater monitoring revealed that concentrations of TCE in a number of on-site monitoring
wells greatly exceeded the maximum contaminant level (MCL), an enforceable drinking water
standard considered protective of public health by the U.S. Environmental Protection Agency.
Due to the karst nature of the site's limestone bedrock, it is difficult to make an accurate
prediction of groundwater flow from the site and possible contaminant migration. ANAD
identified and tested private wells near the site. TCE was detected on one occasion in a private
well at a concentration above the MCL. ANAD has also tested Coldwater Spring, a source of
water for the Anniston Water Works, and detected TCE at levels below the MCL. Despite these
detections, drinking water from all of these sources is considered to be safe to drink. ANAD is
continuing its groundwater monitoring and public outreach efforts, as well as undertaking other
studies to better define groundwater movement and to clarify the extent of possible TCE
groundwater contamination associated with ANAD. ATSDR recommends that ANAD continue
efforts to identify and test private wells in the potentially contaminated areas.
Anniston Army Depot (ANAD) is an active facility occupying 15,200 acres in Calhoun County, Alabama, about 8 miles west of the city of Anniston (see Figure 1) and south of Fort McClellan's Pelham Range. The depot consists of an ammunition storage area (ASA), an industrial area, and an administrative and housing facility (see Figure 2). The ASA, which occupies over 90% of the depot, contains 1,300 storage magazines and an ammunition maintenance workshop complex (Jacobs Engineering Group, Inc., 1994). The industrial area, located on 520 acres in the southeast corner of the depot and known as the southeast industrial area (SIA) (see Figure 3), contains the majority of the depot's industrial processing facilities. Currently, access to the depot is restricted by a perimeter fence.
ANAD was built over 50 years ago as an ammunition storage depot, but its mission has expanded to include rebuilding and maintaining equipment such as tanks, missiles, and small arms. The majority of these industrial activities were conducted in the SIA. During site operations, a variety of hazardous wastes were generated and disposed of within the SIA boundaries. Until 1981, ANAD disposed of most of its hazardous waste (including heavy metals, chlorinated organic solvents, and explosive compounds) in unlined lagoons, trenches, landfills, and sumps. As a result of normal operations and a number of spills involving hazardous materials, environmental media may have been contaminated. Since 1981, ANAD has disposed of its hazardous waste in licensed off-site landfills.
ANAD began the process of site characterization and remediation in the 1980s under the Army's Installation Restoration Program (IRP) and has continued these tasks under an agreement with the U.S. Environmental Protection Agency (EPA) Region IV and Alabama Department of Environmental Management (ADEM). Most of the ANAD environmental investigations have focused on the SIA area. As a result of contamination detected on site, EPA placed the SIA on the National Priorities List (NPL) in 1989. ANAD completed a Phase I remedial investigation (RI) in 1994 and its Phase II RI of the SIA in May 1998. ANAD submitted a final report of the Phase II RI to EPA and the state of Alabama in June 1998 (Ware, 1998). Through these investigations, ANAD confirmed that contaminants had migrated into on-site groundwater. ANAD completed RI field work for the ASA in the June 1998. Information gathered through this effort will provide information on the extent of contamination in this area.
EPA has designated 44 solid waste management units (SWMUs) at ANAD: 29 SWMUs in the SIA and 15 in the ASA. SWMUs are identified under the Resource Conservation and Recovery Act (RCRA) as various on-site disposal areas and locations of spills or releases that contain, or are suspected to contain, contamination or waste. Table 1 summarizes the waste disposal history, investigation results, current status, and the Agency for Toxic Substances and Disease Registry's (ATSDR's) evaluation of public health hazards for each SWMU. For regulatory and remedial purposes, the SWMUs in the SIA have been grouped into three broader areas of contamination, or operable units (OUs), having geographic similarities: the on-site soil OU, the on-site groundwater OU, and the off-site groundwater OU (ANAD, 1997). The on-site groundwater OU includes the shallow aquifer beneath the site, while the off-site OU includes all other groundwater that may be affected by on-site contamination, including the deep on-site aquifer and the shallow and deep off-site groundwater. Clean-up measures for the ASA will be addressed following completion of the RI/feasibility study (FS) for that area.
Since characterizing contamination at the SIA, ANAD has implemented a number of early clean-up measures, including the dredging/excavation and off-site disposal of contaminated soil and sludge from the chemical sludge waste pits (SWMU 1), the old lagoons (SWMU 12), and the Building 130 sump (SWMU 25). In addition, ANAD implemented a pump-and-treatment system in 1990 and continued operation of the Building 114 Dewatering and Treatment System. This measure was taken to control the spread of groundwater contaminated with volatile organic compounds (VOCs) at concentrations above EPA's maximum contaminant level (MCL), to treat contaminated groundwater captured beneath the Trench, the Landfill, and the Northeast areas of the SIA, and to monitor contaminant response to remediation. Because this was an interim action (through the interim ROD of 1991), ANAD will implement additional measures to treat the full extent of the on-site groundwater contamination problem. Furthermore, ANAD initiated the ecological risk assessment of the off-site groundwater RI in 1998.
In addition to characterizing contamination at the site, ANAD continues to study groundwater
flow and possible contaminant migration from the site. ANAD completed a dye tracer study in the
Trench, the Landfill, and the Northeast areas of the SIA in 1994 (EWC, 1994). Results from the
study suggest that a hydraulic connection exists between on-site areas and off-site groundwater. A
more comprehensive dye tracer study, completed in July 1997, suggested that the area
surrounding the SIA lacks features such as sinkholes and disappearing streams associated with
conduit porosity in the bedrock that is common to karstic systems and known for rapid movement
(SAIC, 1997a). ANAD continues to monitor the groundwater movement. As a next step, ANAD
is continuing a geophysical study, which should provide information on the complex geologic
systems beneath the SIA that influence groundwater and contaminant movement.
ATSDR examines demographic information, or population information, to identify the presence of sensitive populations, such as young children and the elderly, in the vicinity of a site. Demographics also provide details on residential history in a particular area--information that helps ATSDR assess time frames of potential human exposure to contaminants. The following presents demographic information for the area surrounding ANAD.
Calhoun County is predominantly rural, especially to the north and west. The county, which has a total population of 115,000, encompasses an area of 610 square miles. The city of Anniston, an industrial and agricultural area of approximately 26,000 residents, is located roughly 8 miles east of ANAD (Haskew, 1996; US ACE, 1991; QST Environmental, Inc., 1998). Several other small communities border ANAD to the south and east, with the larger towns of Oxford and Coldwater located even further to the south and east (Figure 1). Approximately 4,217 people live within a 1-mile buffer of the site, including 362 children ages 6 and younger and 628 people ages 65 and older (ATSDR, 1996a). ANAD employs approximately 3,000 people and is the largest employer in Calhoun County (ANAD, 1998). In addition, three military staff members and their families live in the housing complex at ANAD. Fort McClellan's Pelham Range, which borders ANAD to the north, is scheduled to close under the Department of Defense's (DOD) Base Realignment and Closure program; plans for its reuse are currently being developed (QST Environmental, Inc., 1998).
Many people in Calhoun County, including residents of Anniston, Coldwater, and parts of Oxford, receive their water from the Anniston Water Works, as do the Army depots at ANAD and Fort McClellan. (In addition, Anniston uses the Earl C. Knowlton Treatment Plant for stand-by services. This plant draws its water from Hillabee Lake [Ware, 1998].) The water works draws its water solely from the artesian Coldwater Spring, a groundwater source located between 1 and 2 miles south of ANAD. About 58,000 people (roughly 50% of the Calhoun County community) are served by the Anniston Water Works; other Calhoun County residents are served by four smaller public water supply systems (i.e., Oxford Water System and Sewer Board, Calhoun Water System, Jacksonville Treatment Facility, and Weaver City Water Supply) or by private wells. The four smaller public water supplies also obtain water from groundwater sources. Some private wells exist in the area surrounding ANAD, although the exact number of wells is not known.
The groundwater in the area surrounding ANAD flows in an unconsolidated aquifer and a bedrock aquifer. Groundwater movement in both the unconsolidated and bedrock aquifers is difficult to predict, but it tends predominantly toward the south and west, and to a lesser extent toward the southeast (SAIC, 1997a; Ware, 1998). The unconsolidated aquifer consists of a shallow, low-permeable sandy to silty clay zone and a deeper layer with permeability that ranges between low and high. The underlying bedrock aquifer is characterized by a fracture and karst setting in a limestone formation, but it lacks the well-developed conduit systems common to karst systems that allow rapid water movement (SAIC, 1997a, 1997b). The bedrock aquifer and the deep portion of the unconsolidated zone are the most likely principal water-bearing portions. The water table, or the top of the saturated zone, is seasonally 5 to 10 feet below ground surface in most areas of the SIA.
The major surface water body in the SIA portion of ANAD is Dry Creek, a small perennial creek classified as a fish and wildlife stream by the state of Alabama. Dry Creek originates in the southwest corner of Anniston, passes through the SIA just north of the Chemical Waste Burial Pit, flows along ANAD's southeastern boundary, and eventually flows into Choccolocco Creek, located 3 miles south of ANAD. Most surface water from the SIA portion of ANAD drains into Dry Creek. In the past, four treatment areas directly discharged into Dry Creek, but currently only stormwater outfalls and non-contact cooling waters discharge to the creek (Ware, 1998; Abston, 1998). Most of the ASA is drained by Cane Creek, while drainage in southwest corner of ANAD is divided between the Blue Eye Creek and Eastaboga Creek Drainage Basins (Abston, 1998).
Another industrial facility (Monsanto) in Calhoun County has been identified as a source of
chemical releases. Currently, the ADEM is investigating environmental conditions and overseeing
cleanup at that site. The presence of contamination associated with the other facility, which is
more than 4 miles away, should not adversely affect ANAD's environmental investigations or
cleanup efforts at ANAD.
ATSDR prepared a preliminary public health assessment (PHA) of the ANAD site in 1989 and
conducted site visits in 1991 and 1994 (ATSDR, 1989, 1991, 1995). From these site visits and a
review of the data then available, ATSDR did not identify any completed exposure pathways
posing public health hazards. ATSDR determined that additional data were needed to evaluate
more fully several potential exposure pathways, including the groundwater pathway, and, of
lesser concern, the on-site soil pathway and the potential hazards posed by surface water and
sediment in Dry Creek. (For a definition of completed and potential exposure pathways, see the
Glossary in Appendix A.) As a continuation of it's assessment process, ATSDR reviewed recent
environmental data and prepared this PHA to address potential health hazards at ANAD.
The availability and reliability of information determine the validity of the analyses and conclusions drawn in this document. In preparing this PHA, ATSDR relied on environmental data and on discussions with ANAD representatives and other local and federal agency representatives. The majority of the environmental data presented in this PHA come from monitoring programs and more detailed studies conducted by private contractors under contract with the U.S. Army Environmental Center (USAEC). These include the November 1994 Phase I RI and March 1997 Phase II Draft and May 1998 final RI reports, the June 1994 and May 1998 Groundwater Tracing Studies reports, and quarterly monitoring reports. Quality assurance and quality control measures followed with regard to chain-of-custody, laboratory procedures, and data reporting are identified in the associated reports.