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The Agency for Toxic Substances and Disease Registry (ATSDR) evaluated environmental data and exposure information associated with the Air Force Plant PJKS (AFP PJKS) site and determined that the site poses no apparent public health hazard.

AFP PJKS is located on a 464-acre parcel of land, northwest of Waterton, Colorado, in the foothills 20 miles south-southwest of Denver. The site is surrounded by approximately 5,200 industrially zoned acres owned by Lockheed Martin Astronautics (formerly known as the Martin Marietta Company). Operations conducted at the site include missile assembly, small-engine testing, and fuels development. Between 1957 and 1960, AFP PJKS assembled and tested engines for Titan I missiles, and between 1960 and 1962, the plant supported production of Titan II missiles. Since 1962, the plant has produced Titan III Space Launch Vehicles. The U.S. Environmental Protection Agency (EPA) placed the site on the National Priorities List (NPL) in 1989 because groundwater and soil were contaminated by chlorinated organic solvents (used to rinse contaminated equipment) and hydrazine- and petroleum-based fuels (used to test rockets and heat buildings). Investigations have shown that most of the contamination is contained within the AFP PJKS property, although some contamination has migrated via groundwater to the Lockheed Martin Astronautics (LMA) property.

During the 1980s, elevated levels of chemicals were measured in the alluvium of the South Platte River, which is downgradient from the AFP PJKS and the LMA facilities and near Denver Water's Kassler Water Treatment Plant. In 1983, low levels of trichloroethylene (TCE) and 1,1,1-trichloroethane (1,1,1-TCA) were detected in the plant's infiltration galleries. (The infiltration galleries at the plant were closed the following year.) Although the measured levels in the infiltration were below the EPA's maximum contaminant levels (MCLs), community members expressed concern about potential health effects associated with drinking Denver municipal water originating from the Kassler Water Treatment Plant. Community members also expressed concern about contamination that may have entered nearby surface water bodies, including the South Platte River and Chatfield Reservoir, both of which are used for recreation. Since 1985, several environmental studies have investigated environmental contamination in the infiltration galleries and its potential relation to AFP PJKS. LMA continues to monitor groundwater quality in the area and the Air Force is currently developing a long-term monitoring program for a subset of wells investigated during the remedial investigation.

In response to community concerns, ATSDR visited the AFP PJKS site and met with Colorado Department of Public Health and the Environment representatives in 1991. At that time, no immediate public health hazards were identified. ATSDR revisited the site in 1997 to reconfirm that no immediate public health hazards exist and to further evaluate community health concerns. Throughout this document, ATSDR evaluates these concerns.

Based on a thorough review of the available data, ATSDR concludes that the contaminated groundwater beneath the site poses no public health concerns for AFP PJKS and LMA employees or private well users. Employees receive drinking water from municipal and bottled water sources, and private wells are not located in the immediate vicinity of the site.

ATSDR also evaluated potential human exposures associated with drinking water from the Kassler Water Treatment Plant. Precise water quality monitoring data are not available for the infiltration galleries prior to 1983, when TCE and 1,1,1-TCA were detected. The water quality data collected prior to the 1983, reflective of the testing practices, standards and methodologies commonly in use at the time, were often either qualitative observations or less precise analyses than collected in subsequent years. Data that were collected before the 1983 indicate only low levels of chromium in the plant's infiltration galleries.

Lacking detailed information on past water quality, ATSDR does not know with certainty whether, or to what extent, the volatile organic compounds or other contaminants might have been present in the infiltration galleries before 1983. Because of these limitations, ATSDR conducted an evaluation of past potential human exposure based on conservative assumptions designed to overestimate the amount of contaminants to which people may have been exposed. ATSDR assumed that, in the past, Denver residents drank water supplied by the Kassler Water Treatment Plant containing the highest known levels of chemicals found in the infiltration galleries for long periods of time. ATSDR determined that, even under this highly conservative, yet unlikely scenario, drinking the municipal drinking water supplied by the Kassler Water Treatment Plant would not lead to adverse health effects. As noted, the infiltration galleries were closed in 1984, thereby eliminating the potential for exposure to site-related contaminants in the municipal drinking water supply. No exposures are currently occurring through municipal water, nor are they expected to occur in the future.

ATSDR also concludes that because site-related contaminants have not been detected in the South Platte River, it is highly unlikely that the water of the South Platte River has posed a health hazards to people swimming or wading in the river. Because about 85% of the water entering the Chatfield Reservoir originates from the South Platte River, the reservoir water is also safe for recreational use.


Site Description and History

Air Force Plant PJKS (AFP PJKS) is located on a 464-acre parcel of land, northwest of Waterton, Colorado, and in the foothills 20 miles south-southwest of Denver (Figure 1; ASC/EMR, 1997). The site is surrounded by approximately 5,000 acres owned by Lockheed Martin Astronautics (formerly known as the Martin Marietta Company; Figure 2; Engineering Science, 1988).

Operations conducted at the site include missile assembly, small-engine testing, and fuels development. Between 1957 and 1960, AFP PJKS assembled and tested engines for Titan I missiles, and between 1960 and 1962, the plant supported production of Titan II missiles. Since 1962, the plant has primarily supported production of Titan III Space Launch Vehicles. Chlorinated organic solvents (used to rinse contaminated equipment) and rinse water containing petroleum-based and hydrazine fuels used in testing and developmental activities have been released to on-site soils and discharged into containment ponds. Also reported were some large releases (perhaps as much as 100,000 gallons) of waste water containing detectable levels of hydrazines, which were totally contained in the deluge containment pond (the T-8A pond) (Bondarewicz, 1996). Hydrazines (referring collectively at this site to hydrazine, monomethylhydrazine, and unsymmetrical dimethyl hydrazine [UDMH]) are clear, colorless liquids used for rocket fuels. Normal operations and waste disposal practices at the LMA property surrounding the AFP PJKS site were also responsible for releases to soil and surface water. Some contaminants at each of these sites have also migrated to the groundwater (Engineering Science, 1988).

Principal site contaminants are trichloroethylene (TCE), 1,1,1-trichloroethane (1,1,1-TCA), vinyl chloride, fuel products, n-nitrosodimethylamine (NDMA)--a breakdown product of UDMH --benzene, and some metals. Most of the contamination reportedly is contained on the AFP PJKS property, though some contamination has migrated via groundwater to surrounding property owned by LMA (Engineering Science, 1988; U.S. Air Force, 1999).

Through the Installation Restoration Program (IRP), the Air Force investigated several sites that were believed to be contaminated from routine operations or accidental spills. In 1984, the Air Force began a Phase I records search and identified several sites that could pose public health hazards. These included the deluge containment pond (the T-8A Pond) that received treated rinse water from rocket tests using hydrazines; the D-1 Landfill that served from 1970 to 1974 as a disposal site for construction debris and solid waste; and other areas that were used for fuel storage. AFP PJKS also conducted several rounds of surface water and groundwater monitoring (Engineering Science, 1988; Chem-Nuclear Geotech, Inc., 1992).

In 1986, the Air Force completed a confirmation/quantification study that included a preliminary site investigation. Based on the results of this study, the Air Force conducted its first remedial investigation/feasibility study (RI/FS), which was completed in 1989. The U.S. Environmental Protection Agency (EPA) placed the site on the National Priorities List in 1989. The Colorado Department of Public Health and the Environment (CDPHE) is providing oversight and negotiating an agreement with the Air Force that will further define their roles in cleanup activities. Under the Resource Conservation and Recovery Act (RCRA), the Air Force remediated underground storage tanks (USTs) and associated contaminated soil. To date, the Air Force has safely removed 14 USTs. In addition, they have removed buried drums from the D-1 landfill containing small quantities of low-level radioactive magnesium-thorium and transported the drums to a regulated disposal facility. The drums were intact, rust-free, and emitted only background levels of radioactivity (U.S. Air Force, 1997; Parsons Engineering, 1998).

As a result of the environmental investigations to date, the Air Force has identified 59 IRP sites. The Air Force grouped the IRP sites into six geographic or process-related operable units (OUs) to facilitate the site cleanup process. In addition to the 59 sites, two areas of concern (AOCs) are being investigated under both IRP and RCRA programs. The Air Force has determined that 18 of the 59 sites require no further action either because of no or only low levels of contaminants exist at the site or because of previous corrective action. The Air Force considers 8 of the 59 sites to be "compliance" sites (e.g., active sites, sites regulated by RCRA or the Toxic Substance Control Act) and, as such, currently excludes these from the IRP. Table 1 summarizes the waste disposal history, investigation results, current status, and ATSDR's evaluation of public health hazards for IRP sites and AOCs. The Air Force recently completed additional site characterization activities at the remaining 33 sites and two AOCs, and supplemental RI report was released in the spring of 1999 (ATSDR, 1997a; U.S. Air Force, 1998; U.S. Air Force, 1999).

Site Visits and Community Concerns

As part of the public health assessment process, the Agency for Toxic Substances and Disease Registry (ATSDR) conducted an initial scoping visit and met with representatives from the Air Force, the AFP PJKS facility, EPA, and CDPHE on June 3, 1991 (ATSDR, 1991). ATSDR gathered information regarding potential pathways of human exposure to contaminants and held session(s) with the public to gather information about community health concerns. From these meetings and a review of the data then available, ATSDR determined that no immediate threats to public health existed, but that several potential exposure pathways and community health concerns required further evaluation.

ATSDR revisited the AFP PJKS site on March 13, 1997, to confirm that no situations requiring immediate attention existed and to further evaluate community health concerns. ATSDR met with representatives of CDPHE, LMA, and the Air Force. ATSDR attended a Restoration Advisory Board (RAB) meeting, where ATSDR staff listened to community health concerns and presented an overview of the public health assessment process (ATSDR, 1997a).

During the March 1997 RAB meeting, members of the community and the RAB expressed various concerns regarding AFP PJKS. In addition, a community relations plan prepared by the Air Force in 1992 and updated in 1997 identifies a number of concerns held by community members at that time (these concerns were voiced during community interviews conducted at AFP PJKS) (Chem-Nuclear Geotech, Inc., 1992; ASC/EMR, 1997). On July 23, 1997, ATSDR scheduled public availability meetings to provide an opportunity for the public to express any site-related health concerns. Less than 10 people attended. ATSDR has grouped the concerns expressed in these various forums into the areas of general concern listed below and further evaluates these concerns in this public health assessment:

  • Has groundwater contamination detected at AFP PJKS affected nearby drinking water wells and, if so, has or will that contamination result in adverse human health effects?

  • Was the drinking water supplied by the Kassler Water Treatment Plant safe to drink?

  • Have the South Platte River and Chatfield Reservoir been contaminated to levels that might be harmful to recreational users?

Demographics and Land Use

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. Demographic information for the residential areas surrounding AFP PJKS is presented in this section.

AFP PJKS currently employs approximately 100 individuals. Land in the immediate vicinity of the site is owned by LMA and is used for plant-related industrial development, including designing, developing, and manufacturing of space exploration and defense equipment. Approximately 11,000 workers are employed at the LMA site. Both PJKS and LMA are zoned for industrial use, so no residential property exists on either site. LMA has sponsored environmental studies at their property to investigate the nature and extent of contamination related to these past facility operations and to identify appropriate remedies (Geraghty & Miller, Inc., 1990; Clement Associates, 1990).

Using 1990 U.S. Census data, ATSDR determined that approximately 420 people live within approximately 1 mile of the AFP PJKS site boundary.A majority of this population lives east near the Chatfield Reservoir (Earth Tech, 1996). In the mountains to the west, there are a few scattered homes, primarily in the higher elevations. The nearest privately-owned properties to AFP PJKS are two vacant residences, approximately a quarter of a mile west of the AFP PJKS boundary. Those residences are located both topographically and hydrogeologically upgradient of the site. It is not known when these properties were last inhabited.

As a result of growth in the greater Denver area over the past 10 to 15 years, land north of the site has experienced a surge in residential development. Deer Creek Mesa, the closest residential community to the site, consists of approximately 60 homes located 1.5 to 2 miles northwest of AFP PJKS (ASC/EMR, 1997). All but 10 homes at Deer Creek Mesa have been connected to Denver Water (DW) public services. The next closest communities are the Ken Caryl Ranch Development, located 5 to 6 miles northwest of the site, the Roxborough Park and Village subdivisions, located 3 to 4 miles south of the site, and the Friendly Hills subdivision, located approximately 5 miles northeast of AFP PJKS. (Chem-Nuclear Geotech, Inc., 1992). Littleton, 5 miles north of the site, is the nearest incorporated city. The Chatfield State Recreation Area to the east of AFP PJKS is heavily used for hiking, camping, swimming, and boating (Clement Associates, 1990).

DW owns the land to the southeast of the AFP PJKS. The Kassler Water Treatment Plant, located on DW land to the southeast of the AFP PJKS and LMA sites and along the South Platte River, was used until 1985 for drinking water supplies (see Figure 3). The Platte Canyon Reservoir once served as a settling pond supplying water to the Kassler Water Treatment Plant. Since closure of the Kassler Water Treatment Plant, Platte Canyon Reservoir water has not been routed to other water treatment plants (e.g., Foothills Treatment Plant). Instead, the Platte Canyon Reservoir has served only as a water storage facility: the water released in exchange for DW diversions of streamflow elsewhere. Currently, the Platte Canyon Reservoir is fenced and inaccessible to the public (AFP PJKS, 1997).

AFP PJKS is located within the South Platte River basin. The South Platte River originates along the Continental Divide of the Rocky Mountains west of the AFP PJKS (Engineering Science, 1988). The river, which has been used for flood control, fishing, and other recreational activities, flows northeastward through Waterton, Colorado, to the Chatfield Reservoir (Clement Associates, 1990). The Chatfield Reservoir is used for recreational activities, including swimming (CDPHE, 1992). The public beach at the reservoir is open from the end of May to the beginning of September (Chatfield State Park, 1998).

The majority of the AFP PJKS property is drained by the tributaries of Brush Creek, which originate in the foothills to the west of the LMA property (see Figure 2). About 60% of AFP PJKS lies within the upper reaches of the small watershed drained by the East Fork of Brush Creek; other, smaller portions of the site are drained by the West Fork of Brush Creek and by the northward draining Lariat Gulch. The East Fork of Brush Creek is an intermittent stream that typically flows in response to precipitation and snow melt. The West Fork and Lariat Gulch generally flow intermittently and were dry (on AFP PJKS property) during ATSDR's site visits. The East and West Forks flow southeast through AFP PJKS property and eventually converge to become Lower Brush Creek near the southeastern boundary of LMA before emptying into the South Platte River downstream of the Kassler Water Treatment Plant. (Filter Gulch, a transient gully, flows through the LMA property [but not through AFP PJKS property] and empties into the Last Chance Ditch on DW property.) The Lower Brush Creek is designated for recreation (i.e., fishing) and agricultural uses (Engineering Science, 1988). The South Platte River eventually empties into the Chatfield Reservoir; the river accounts for approximately 85% of the water in the reservoir.

Storm water runoff at AFP PJKS flows into a man-made storm water collection system. The system consists of a network of open concrete flumes, culverts, and earthen ditches that eventually empty into T-8A Pond (a concrete containment pond) or Brush Creek (Earth Tech, 1996). The system also has been used to collect water from waste-generating buildings. Today, the state of Colorado permits the system. During a site survey in 1986, CDPHE identified 91 pipes on the AFP PJKS and LMA sites that emptied in either Brush Creek or Filter Gulch. While some pipes may have carried process waste, most pipes were building foundation drains that carried non-wastewater fluids (CDPHE, 1992; Lockheed Martin Astronautics, 1998).

Quality Assurance and Quality Control

In preparing this public health assessment, ATSDR relied on the information provided in the referenced documents. Documents prepared for the IRP program meet specific standards for adequate quality assurance and control measures for chain-of-custody procedures, laboratory procedures, and data reporting. The validity of the analyses and conclusions drawn in this document are dependent upon the availability and reliability of the referenced information. The environmental data presented in this public health assessment are from reports produced by the Air Force, LMA, CDPHE, and DW. The limitations of these data have been identified in the associated reports.

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