PUBLIC HEALTH ASSESSMENT
F.E. WARREN AIR FORCE BASE
CHEYENNE, LARAMIE COUNTY, WYOMING
The Agency for Toxic Substances and Disease Registry (ATSDR) prepared this public healthassessment (PHA) to evaluate exposure pathways and to respond to community concerns aboutpast, current, and potential future exposures to contaminants originating at the F.E. Warren AirForce Base (F.E. Warren). ATSDR reviewed available data and exposure information anddetermined that this site poses no apparent public health hazard.
F.E. Warren is an active military facility located in Laramie County, west of the city ofCheyenne, in southeastern Wyoming. The base encompasses approximately 5,900 acres. Themajority of base facilities and housing, including an 11-acre airfield, are located in the southernportion of the base. The northern portion of the base is characterized by open prairie formerlyused as firing ranges to test artillery. F.E. Warren serves as an U.S. Air Force (USAF) SpaceCommand base. The majority of contamination identified at F.E. Warren resulted from pastwaste and resource management. In February 1990, the U. S. Environmental Protection Agency(EPA) placed F.E. Warren on the National Priority List because of groundwater contamination.
In preparing this PHA, ATSDR reviewed available data from F.E. Warren, EPA, the state ofWyoming, and the city of Cheyenne. ATSDR also spoke with community members about theirhealth concerns. From a review of available data and discussions with community membersabout their health concerns, ATSDR identified dust blowing from the active borrow area (acurrent community concern), contamination of private wells by volatile organic compounds andmetals, and recreational use of Landfills 2 and 3 as the principal possible exposure pathways of concern.
Residents in the Western Hills neighborhood, which abuts the northeastern base boundary, haveexpressed concern about exposure to windblown dust from an area of active excavation. TheUSAF began excavating soil at the active borrow area in April 1997 for use as landfill cappingmaterial. Excavation is scheduled to be complete on or before August 1999. After a detailedreview of soil data collected before and during excavation, ATSDR concluded that contaminantsare not present in soil at levels that are likely to pose a public health hazard. In addition, theUSAF has implemented a dust control program to limit dust generation during excavation. Thisprogram includes wetting the soil, applying a tackifier (a sticky, sugar substance that creates acoating on the soil surface), and ceasing activities in high winds.
Residents in two neighborhoods located along the southern base boundary, Nob Hill and FairAcres, have used or continue to use groundwater pumped from private wells as their primarydrinking water supply. After detailed review of data from private wells in these twoneighborhoods, ATSDR concluded that contaminants present in drinking water do not pose ahealth hazard to residents from past exposure based on conservative estimates of how often andhow long residents may have been exposed. However, private wells within Nob Hill were onlysampled once in 1994. Additional sampling may further support this conclusion. To preventcurrent and potential future exposures, the USAF connected homes in the Nob Hill neighborhoodto the Cheyenne municipal water supply. Residents in the Fair Acres neighborhood continue touse their private wells. Some residents, however, purchase bottled water for their drinking water.In addition, wells were resampled in 1997 and contaminant concentrations were found to bedecreasing. The Wyoming Department of Environmental Quality and local health officialscontinue to work with Fair Acres residents to identify potential contaminant sources and preventharmful exposures.
An on-base family housing area is located proximate to Landfills 2 and 3 in the southern portionof F.E. Warren. Access to these landfills is unrestricted and children have been observed bikingand playing in these areas. Therefore, ATSDR also evaluated surface-soil data from Landfills 2and 3 and surface water and sediment data from an unnamed stream that passes through Landfill2. After detailed review of the data, ATSDR concluded that contaminants present in these mediado not pose a health hazard to past, current, or potential future recreational users from the nearbyhousing area. The USAF has completed or is conducting remedial actions at Landfills 2 and 3,based on 1995 site investigations, to prevent current and future exposures. Landfill 2 iscomposed of three subunits: Landfill 2a, 2b, and 2c. Removal actions, which include partial ortotal excavation of waste, were completed at Landfill 2c and are scheduled to begin at Landfills2a and 2b in April 2000. At Landfill 3, the USAF is scheduled to conduct additional investigations in 1999 and begin construction of a landfill cap in April 2001.
F.E. Warren Air Force Base (F.E. Warren) is an active military facility located in LaramieCounty, west of the city of Cheyenne, in southeastern Wyoming. The base encompassesapproximately 5,900 acres. The majority of base facilities and housing, including an 11-acreairfield, are located in the southern portion of the base. The northern portion of the base ischaracterized by open prairie formerly used as firing ranges to test artillery. Residentialdevelopment, including the Western Hills neighborhood, and commercial developmentassociated with Cheyenne are located east of F.E. Warren. Open land and the Nob Hill and FairAcres neighborhoods are to the south. Open land is present to the west and north of the site (seeFigure 1) (USGS, 1991a; F.E. Warren, 1998b and 1998d).
Military functions began at the site of F.E. Warren in 1867 when a U. S. Army outpost, namedFort D.A. Russell, was established. The name was changed to Fort F.E. Warren in 1930, and thefacility served as an U. S. Army training facility during and after World War II. In 1947, FortF.E. Warren was transferred to the U. S. Air Force (USAF). Beginning in 1958, F.E. Warrenbecame a Strategic Air Command Base, serving as an operations center first for the Atlasintercontinental ballistic missile, followed by the Minuteman I and III, and finally thePeacekeeper Missile. F.E. Warren is currently a USAF Space Command base and part of the U.S.Strategic Command (F.E. Warren, 1998a). The majority of contamination identified at F.E.Warren resulted from past waste and resource management (F.E. Warren, 1998d).
The Installation Restoration Program (IRP) commenced at F.E. Warren in 1981 with a recordssearch to identify past waste management practices. In addition to reviewing writtendocumentation, the search included contacting community members and past base employees. Asa result of this search, 25 areas of concern were identified at F.E. Warren where hazardousmaterials might have been used, stored, treated, or disposed. The records search identifiedpotential groundwater contamination as a major concern based on reported releases rather thanactual sampling data (F.E. Warren, 1998c).
In February 1990, the U. S. Environmental Protection Agency (EPA) placed F.E. Warren on theNational Priority List because of groundwater contamination. A Federal Facilities Agreement(FFA) was signed between the USAF, EPA, and the Wyoming Department of EnvironmentalQuality (WDEQ) in 1991. The FFA provides the framework for EPA and WDEQ oversight ofongoing investigations and remediation at F.E. Warren (F.E. Warren, 1998c).
A base-wide remedial investigation (RI) was completed by the United States Geological Surveyin 1991. The RI summarized investigations completed under the second phase of the IRP, whichcommenced in 1987. A total of 23 areas of concern and base-wide surface water quality wereevaluated under the RI. Investigations included an initial assessment of contamination and amore comprehensive assessment designed to quantify the extent, direction, and rate ofcontaminant migration. The RI concluded that trichloroethylene (TCE) in groundwater was thegreatest concern at F.E. Warren and recommended groundwater monitoring (USGS, 1991a; F.E. Warren, 1998a).
After the completion of the base-wide RI, potential contamination sites were divided into ten Operable Units (OUs) and more detailed investigations were conducted. F.E. Warren established OUs based on site type, location, and response actions. In summer 1998, F.E. Warren redistributed sites from the established OUs into new zone designations A through E. The zone designations were based on site type, location, and affected media. Ongoing investigations will be conducted by zone versus OU. The zone, OU, and site names are provided in Table 1 and are shown in Figure 2. Investigations are either ongoing or completed at the various sites and zones (F.E. Warren, 1998d). A summary of the sites and associated investigations and remedial actions are provided in Table 2.
|Spill Site 4 |
Spill Site 7
Groundwater TCE Plume A
|D2||5 and 10 |
|Fire Protection Training Area 1 |
Fire Protection Training Area 2
Acid Dry Wells
Groundwater TCE Plumes B and C
|Spill Site 2 |
Groundwater TCE Plumes D and E
|Spill Site 1 |
Spill Site 3
Spill Site 5
Spill Site 6
Open Burn/Open Detonation Area
In December 1998, the Agency for Toxic Substances and Disease Registry (ATSDR) conducted asite visit at F.E. Warren. ATSDR met with representatives of the USAF and reviewed existinginformation. The intent of this visit was to gain an understanding of site conditions and remedialactions and to identify potential community concerns.
ATSDR held public availability meetings in communities surrounding F.E. Warren duringJanuary 1999. Public availability meetings provide a forum for community members to discusstheir concerns about site contamination issues. ATSDR used information gathered at thesemeetings to complete the public health assessment (PHA).
F.E. Warren and Cheyenne are located in Laramie County in southeastern Wyoming. TheCheyenne population is approximately 50,000 and the county population is approximately68,700. The Cheyenne and county populations are reportedly increasing slowly. The militaryemploys approximately 8.6 percent of the Laramie County population. Cheyenne, residentialneighborhoods, and commercial businesses are located east of F.E. Warren. Open land,agriculture, and low-density residential neighborhoods are located along the remaining baseboundaries (F.E. Warren, 1998c and 1998d).
In 1997, F.E. Warren supported an on-base population of approximately 3,400 residents, adecline from the nearly 3,800 residents in on-base housing in the early 1990s. On-base housingoccupies approximately 280 acres of the base in the southern and central portions of F.E. Warren.Landfills 2 and 3 are located proximate to the southern housing area. The Firing Range is to thenorth and several of the spill sites are to the south of the central housing area. Military personnel,including their families and children, may live in the southern or central housing area. Access tothe landfills and spill sites from the housing areas is not restricted. Access to the firing range isrestricted (F.E. Warren, 1998c, 1998d, and 1998e).
Access to F.E. Warren is restricted to military personnel, on-base residents, and civilianemployees. Members of the general public and contractors, however, may enter the base afterregistering their vehicles and obtaining passes. The base is surrounded by a perimeter fence thatis regularly patrolled. People entering the base must pass through a gate with a security guard.Once within F.E. Warren boundaries, however, access to areas found containing contamination isgenerally not limited (F.E. Warren, 1998d and 1998e).
There are no on-base schools. One day care center is located at the western end of RandallAvenue. This center provides care for pre-school children for both military personnel andcivilians in Laramie County. A Head Start program is located along Randall Avenue across fromthe parade grounds. The Head Start program serves families within Laramie County and operatesmorning and afternoon classes for pre-school children (Urban, 1999). Neither the day care centernor Head Start program is located in an area of contamination. Open space and recreational areas,including a family camping area along Crow Creek, are located throughout F.E. Warren. Nocontamination sites are located in areas designated for recreation (F.E. Warren, 1998f).
Several surface water bodies are located within the base and may be used for recreation. CrowCreek flows through the southern portion of F.E. Warren and is the major perennial stream thatdrains the base. Crow Creek gains flow from groundwater discharge and two tributaries:Diamond Creek and an unnamed stream. Diamond Creek is the second largest stream at F.E.Warren and is also perennial along most its length. The unnamed stream is an interrupted stream,with alternating reaches that are perennial, intermittent, or ephemeral. Both Diamond Creek andthe unnamed stream also gain flow through seeps and groundwater discharge. Dry Creek andseveral other unnamed streams are located in the northern portion of the base. These streams areintermittent and not likely frequented by base employees or residents. Three lakes, NorthPearson, South Pearson, and Centennial Lakes, are located at F.E. Warren. Each of these lakes isused for recreation, including fishing. The USAF stocks North and South Pearson Lakes withfish from the U. S. Fish and Wildlife Service. Full size fish are stocked two or three times a year.Recreational users may use these fish for human consumption. At Centennial Lake, only catchand release fishing is permitted. No areas of contamination were identified in recreational areas (F.E. Warren, 1998d, 1998e, and 1998f).
In preparing this public health assessment (PHA), ATSDR relied on information provided in thereferenced documents. ATSDR assumes that adequate quality assurance and control measureswere followed with chain-of-custody, laboratory procedures, and data reporting. The validity ofthe analyses and conclusions drawn in this document are dependent on the availability and reliability of the referenced information.