PUBLIC HEALTH ASSESSMENT
TOOELE ARMY DEPOT (NORTH AREA)
TOOELE, TOOELE COUNTY, UTAH
The Agency for Toxic Substances and Disease Registry (ATSDR) conducted a public health assessment (PHA) to evaluate possible exposures to chemical and physical hazards and to respond to community concerns about past and current exposures to contaminants associated with the Tooele Army Depot (TEAD). TEAD is an active military installation which currently includes an area occupying approximately 25,000 acres in eastern Tooele County, Utah. As part of the PHA process, ATSDR conducted an initial site visit from April 13 to April 17, 1998, and revisited the site from January 17 to January 24, 2001. This document summarizes the site-specific information reviewed by ATSDR, provides an explanation of the process ATSDR uses to conduct a PHA, and presents the results of our analysis and evaluation of public health hazards (i.e., the potential for community members to be exposed to harmful contaminants detected at TEAD).
ATSDR evaluated environmental information for all areas of contamination on site and identified four potential exposure pathways requiring a more comprehensive evaluation. These include: 1) use of on-site drinking supply wells at TEAD; 2) domestic use of groundwater from off-site wells (i.e., municipal and private off site wells) located near the north-east portion of TEAD; 3) potential exposure to air contaminants from open burning/open detonation (OB/OD) activities at TEAD; 4) potential exposure to ordnance and explosive waste on private farm land adjacent to TEAD OB/OD activities, and 5) exposure to lead-contaminated soil from the trap and skeet range. In addition, we reviewed properties to be turned over for non-military use. None of those possible exposures currently poses a public health hazard. In 1999, ATSDR concluded that unexploded debris or shrapnel from the OB/OD operations, which had landed in the agricultural area near the base boundary, posed physical hazards.
The primary goal of this PHA was to evaluate potential sources of contamination associated with TEAD and to identify and evaluate potential exposure pathways in the surrounding communities. The focus is on TEAD sources of contamination that currently, or in the past, release contaminants that might result in exposure to residents who live near TEAD. ATSDR evaluated whether residents surrounding the facility would likely come into contact with those contaminants and, if contact was possible, evaluated the potential exposure.
Potential Exposure to Contaminated Groundwater: No Public Health Hazard
Groundwater is the primary source of drinking water in the Tooele Valley. Most potable drinking water for the Tooele area comes from deep or intermediate alluvial aquifer wells. Some private residences north, northwest, and northeast of TEAD (greater than 2 miles) rely on shallow and intermediate wells for drinking water. ATSDR reviewed available on-site and off-site groundwater data and evaluated potential past and current exposures caused by drinking water from these sources.
Sources of Groundwater Contamination
Two primary groundwater plumes are present at TEAD: the eastern boundary plume (i.e., the main plume) and the northeastern boundary plume. The main plume, approximately 2 miles at its widest extent, was identified in the early 1980s. The presence of the northeastern boundary plume was supported by groundwater investigations conducted in the mid- and late 1990s, but was suspected as early as 1986. TCE has been the most prevalent contaminant in these plumes, both in extent and concentration. In 1993, a groundwater extraction and treatment system, using an air stripper, began operation. This treatment system has helped contain the main plume and has prevented most of the TCE-contaminated groundwater from migrating beyond the TEAD boundary. Characterization of the northeastern boundary plume is ongoing. The most recent sampling shows that the TCE plume (5 ppb contour) extends nearly 1 mile from the northeast boundary of TEAD and is migrating northwest, in the general direction of groundwater flow. Corrective actions for this plume have not been completed.
Two active supply wells (wells #1 and #3) are used to provide drinking water to TEAD. These wells are upgradient from the two primary groundwater plumes located at TEAD (i.e., east boundary [main plume] and northeast boundary plumes). A source-protection plan has been developed for drinking water from each well, and all monitoring results have met both state and federal drinking-water standards. Both wells are screened in the deep alluvial aquifer and are not being impacted by any contaminated source areas on site.
Off-Site Groundwater Use
Four Tooele City municipal drinking-water wells are located east of TEAD and are upgradient of all TEAD contaminant plumes. The city of Grantsville operates a municipal well approximately 2,000 feet from the northwest boundary of TEAD. This well is approximately 4 miles west of the closest TCE-contaminated groundwater monitoring well. Routine monitoring of drinking water from these municipal supply wells, including volatile organic compounds (e.g., TCE) and metals, has met all state and federal standards for safe drinking water. No TEAD contaminants are present in these drinking-water supply wells at levels of concern.
TEAD drinking-water well #2 was transferred to Tooele City. This is believed to be the drinking-water well closest to the groundwater plumes. Tooele City used it for irrigation during the summer of 2002 and is considering using this well to help meet the city's water needs. ATSDR recommends that if this well is used domestically, it be tested semi-annually for contamination by volatile organic compounds, especially TCE.
Potential Exposure to Air Contaminants: No Public Health Hazard
Since the 1940s, the OB/OD unit of the Tooele Army Depot has been in operation to destroy obsolete munitions. Activities include open detonation of munitions, open burning of propellant, and static firing of rocket motors--all conducted in a controlled environment and under specific meteorologic conditions to minimize the impact on the surrounding communities. The OB/OD unit is in a remote part of the southwest portion of the depot, with no residential areas in close proximity to the operation. The northern base boundary is approximately 4 miles north of the OB/OD site, and downtown Grantsville, the closest community, is about 6 miles north of the OB/OD unit.
Munitions selected for destruction are loaded onto pallets and buried 7 to 10 feet deep in hillside pits. Previously, up to 5,000 pounds of net explosive weight were allowed per pit. During the early 1990s, the maximum net explosive weight was reduced to 1,500 pounds. Since 1996, TEAD has limited it to 750 pounds of net explosive weight per detonation. Open detonation operations are typically performed about 120 days each year, with multiple detonations occurring each day. Most of those days are between late spring and early fall.
Each detonation generates a large plume of smoke and dust from combustion and cover soil. Research shows that water vapor, carbon dioxide (CO2), carbon monoxide (CO), and particulate matter with aerodynamic diameters of 10 microns or less (PM10) are the major by-products of the munition detonations. Other chemicals are also released, but at much lower levels. Visual observations of the plume, dilution calculations, atmospheric transport models and air monitoring all suggest that the concentrations of chemicals are rapidly diluted as the plume travels downwind.
Air-monitoring measurements were taken from Grantsville every 6 days between 1993 and 1997. Results indicate that the ambient air quality of Grantsville, as measured by PM10, was not affected by OB/OD activities. Other chemicals released from open detonation are at significantly lower levels, perhaps as much as 100 to 1,000 times less than the PM10 levels. Because the PM10 concentration in Grantsville did not change as a result of open detonation, we would not expect to see the presence of other chemicals in Grantsville as a result of open detonation operations.
Before 1990, detonations as much as 7 times greater (by weight) were allowed at TEAD. Therefore, actual air concentrations in Grantsville for open detonation operations before 1990 are indeterminate. Results indicate that since 1993, Grantsville residents have not been, and are not currently, exposed to contaminants from OB/OD operations that would be expected to cause adverse health effects.
Physical Hazard Associated With OB/OD Off Depot: Public Health Hazard
In 1993, the Army Corps of Engineers identified ordnance and explosive waste (OEW) present on an active, privately owned agricultural area adjacent to the OB/OD unit. This OEW resulted from previous OD operations when higher amounts of net explosive weight were used. Occasionally, unexploded debris or shrapnel would land in the agricultural area near the base boundary. Although the Army cleared most of the land, some uncleared sections remain. After evaluating this issue, ATSDR released a health consultation in February 1999 concluding that use of the property was a public health hazard because OEW was likely present on uncleared land and the potential for detonation, however remote, from the land use could possibly result in a health impact. Although no accidents on this property are known to have resulted from OEW, and the likelihood of an incident is very small, OEW on private land still represents a public health hazard. This property has been included in the Military Munitions Response Program and the remaining uncleared land will be cleared using this program. ATSDR recommends that the uncleared portion of the land not be farmed until clearance actions are complete.
Properties Turned Over for Non-Military Use
Several TEAD areas have been transferred to Tooele City, including portions of the industrial area and the skeet range. The former skeet range, which may be used for future residential housing, had lead concentrations that exceeded EPA limits for residential use. The Army performed a soil removal remediation action in the fall of 2002. Following approval by DEQ this area will be suitable for residential use. Thus, no areas exist where community members would likely come into contact with soil contaminants from TEAD.
The Tooele Army Depot (TEAD) is an active military installation which currently includes an area occupying approximately 25,000 acres in eastern Tooele County, Utah. TEAD began operations in 1942 and was originally referred to as the Tooele Ordnance Depot (TOD). The original facility functioned as a storage depot during World War II for supplies, ammunition, and combat vehicles.
During the same time period, the U.S. Department of Defense also constructed a chemical weapons storage depot referred to as the Deseret Chemical Warfare Depot (DCWD). DCWD is about 20 miles south of Tooele in Rush Valley, which operated independently of TOD. DCWD, which is currently referred to as the Deseret Chemical Depot, is a 19,355- acre area approximately 35 miles southwest of Salt Lake City in north central Utah. It has been used since the 1940s for storage, renovation, disposal, and burial of various chemical agent munitions (Ebasco 1991).
Since its construction in 1942, TEAD has undergone a number of operational changes that have expanded its mission. For example, in 1955, DCWD was renamed the Deseret Chemical Depot (DCD) and was placed under the command of TOD. In 1961, DCD was officially designated the TOD South Area. In 1962, the depot's name was formerly changed from TOD to TEAD to reflect its larger supply mission.
In 1962, TEAD comprised two separate areas: 1) the North Area (TEAD), which borders the city of Tooele (additional site information about TEAD is provided below), and 2) the South Area (TEAD-S), which is approximately 20 miles south of Tooele (USAEC 1994). TEAD-S is located in a remote area which is mostly surrounded by federal land. There are four towns in the vicinity of TEAD-S: Stockton, Rush Valley, Vernon, and Ophir (Figure 1). These towns have a combined population estimated to be 1,000. The primary industries supported by residents in the area are mining and agriculture (Ebasco 1991).
During the early and mid-1970s, TEAD continued to take on additional responsibilities, including assuming command responsibilities of the Umatilla Depot Activity located in northeastern Oregon, Fort Wingate Army Depot Activity located in New Mexico, Navajo Army Depot Activity in Arizona, and Pueblo Army Depot Activity in Colorado. In 1993, TEAD also assumed command of the Sacramento Army Depot (USAEC 1994). In addition to this expansion of command responsibilities, a Chemical Agents Munitions Disposal System (CAMDS) facility, located in TEAD-S, was constructed in 1977. The CAMDS was designed to develop and proof-test technology related to the disposal of chemical-agent-filled munitions. The CAMDS facility continues to dispose of aging chemical munitions (USAEC 1994).
In March 1993, the Base Realignment and Closure (BRAC) Commission made a recommendation to realign a portion of TEAD. As a result of the realignment process, TEAD would retain conventional ammunition storage and maintenance and demilitarization portions of its mission (North Area). As a result of this realignment, the chemical munition storage and demilitarization mission (South Area) was placed under the Chemical and Biological Defense Command and is currently referred to as the Deseret Chemical Depot (DCD) (HOH Associates, Inc., et al. 1995).
Since only TEAD has been placed on EPA'sNational Priorities List (NPL), the focus of this public health assessment (PHA) will be on contamination associated with TEAD. Source areas of contamination at DCD are being addressed under the Resource Conservation and Recovery Act (RCRA) (Larry McFarland, TEAD, personal communication, July 12, 2001).
TEAD is an active ammunition storage and demilitarization facility occupying approximately 25,000 acres in eastern Tooele County, Utah. It is approximately 35 miles southwest of Salt Lake City in northwestern Utah (Kleinfelder 1998a). TEAD is between the Oquirrh Mountains to the east and the Stansbury Mountains to the west. It is bounded on the northeast by State Route 112 and to the southeast by State Route 36. TEAD is adjacent to the city of Tooele and approximately 5 miles southeast of the town of Grantsville (Figure 1) (Kleinfelder 1998a).
TEAD contains 260 buildings for current operations, 259 buildings that have been transferred to private companies (either directly or through a designated redevelopment agency) as part of the BRAC process, and a total of 920 storage igloos, above-ground magazines, and warehouses. The total storage capacity at the Depot is 2,483,000 square feet (Best Manufacturing Survey 1999). Security at TEAD is maintained by a fence around the entire site and unauthorized access is controlled with gates and signs that specify no trespassing. The main gate is only open during normal hours of operation. All other gates are open on an as-needed basis and under supervision. Signs are posted to alert on-site workers about hazardous waste areas and designated areas where open detonation of ordnance takes place.
Prior to the Department of Defense's decision to realign TEAD under the BRAC process, the majority of activities at the depot were associated with four main areas within the TEAD boundaries (SAIC 1997a) (Figures 2):
- Administration Area
- Industrial Maintenance Area
- Open Revetment Area
- Ordnance Area (includes the ammunition storage igloos and magazines)
In the past, the primary missions of TEAD have involved rebuilding and storing military vehicles and equipment, and storage and demilitarization of conventional munitions. Under the BRAC process, the vehicle and equipment maintenance and storage activities were eliminated in 1997 (Montgomery Watson 1997). Most of the environmental contamination due to the hazardous wastes generated at TEAD were from the following sources:
- Ash and dust, potentially containing heavy metals and organic compounds, generated from sandblasting operations and incinerating munitions and packaging materials;
- Ash and debris generated from open burning and open detonation (OB/OD) of propellants and munitions in unlined pits and burn pans;
- The discharge and disposal of solvents and oils used in vehicle and depot maintenance activities; and
- Other wastes associated with activities at TEAD including pesticides and herbicides, radioactive wastes, detergents, polychlorinated biphenyls (PCBs), and industrial and sewage sludge (Montgomery Watson 1997).
Past waste disposal practices included wastewater discharges to the former Industrial Wastewater Lagoon (IWL) and other unlined wastewater ditches, as well as disposal of solid wastes at various pits and storage areas on site. These practices have resulted in the release of contaminants into the soil, surface water, and groundwater (Kleinfelder 1998a; Montgomery Watson 1997).
An initial environmental assessment of TEAD, completed in 1979, found that a potential for contamination existed on portions of the depot where explosives were burned or detonated in the open (USATHAMA 1979). Additional environmental investigations identified contamination in soils and groundwater resulting from activities associated with equipment maintenance, munitions disposal, and other industrial activities. Contaminants of concern included explosives, lead, cadmium, solvents, waste oils, and PCBs.
In October 1984, the U.S. Environmental Protection Agency (EPA) proposed that TEAD be included on the NPL as a result of groundwater contamination from the IWL and explosives washout facility. The EPA conducted an environmental assessment of the site in August 1987 and completed a groundwater evaluation in May 1988. In October 1990, TEAD was placed on the EPA's NPL (Tooele Army Depot 1994).
As a result, and in accordance with the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), the Army was required to investigate current and past waste disposal practices and the nature and extent of contamination at TEAD. In accordance with a 1991 federal facilities agreement between the Army, EPA, and the Utah Department of Environmental Quality (DEQ), the requirements and schedules for the investigation and remediation of hazardous substances and solid and hazardous waste sites at TEAD were outlined. Several known and potential waste sites at TEAD were designated as sites for environmental study and possible cleanup under CERCLA and some other known or potential sites are being addressed under RCRA, with the state of Utah acting as the lead agency (Tooele Army Depot 1994; US Army 1998).
TEAD contains a number of source areas, referred to as solid waste management units (SWMUs), that are known to or may have released contaminants into the soil and groundwater. Fifty-seven SWMUs have been identified at TEAD. Seventeen of the SWMUs are regulated under the Superfund program, which is part of CERCLA. The remaining 40 SWMUs are being addressed under a RCRA Corrective Action permit. These 40 SWMUs are further divided into 30 SWMUs with suspected releases and 9 SWMUs with known releases, and the Northeast Boundary plume and source area (SWMU 58) (Rust 1994) (Figures 2a, 2b, and 2c).
The 17 SWMUs at TEAD that are being investigated under Superfund have been divided into seven operable units (OUs). The OUs (OU4-OU10) and the corresponding SWMUs are listed below. OUs 1, 2, and 3 are used by EPA to track RCRA Corrective Action sites, but are not investigated under Superfund. OU 1 consists of SWMU 2 (the IWL), OU 2 contains the Known Release SWMUs described below, and OU 3 contains the Suspected Release SWMUs (Larry McFarland, TEAD, personal communications, August 29, 2001).
- OU 4 consists of two SWMUs located in the southeastern portion of TEAD, west and south of the Industrial Maintenance Area:
- The Former Transformer Boxing Area (SWMU 31);
- The PCB Spill Site (SWMU 32); and
- The Former Transformer Storage Area (SWMU 17); and
- PCB Storage Building 659 (SWMU 33).
- The Drummed Radioactive Waste Area (SWMU 9); and
- The Radioactive Waste Storage Building (SWMU 18).
- The Old Burn Area (SWMU 6);
- The Small Arms Firing Range (SWMU 8);
- The Tire Disposal Area (SWMU 13);
- The Building 1303 Washout Pond (SWMU 22); and
- The Old Burn Staging Area (SWMU 36).
- The Chemical Range (SWMU 7);
- The Bomb and Shell Reconditioning Building (SWMU 23);
- Wastewater Spreading Area (SWMU 35); and
- The Ammunition Equipment and Directorate Test Range (SWMU 40).
- The Industrial Waste Lagoon (SWMU 2);
- X-Ray Lagoon (SWMU 3);
- The TNT Washout Facility (SWMU 10);
- The Laundry Effluent Pond (SWMU 11);
- The Sanitary Landfill (SWMU 12);
- The Pesticide Disposal Area (SWMU 15);
- The Battery Pit (SWMU 24);
- The Battery Shop (SWMU 25); and
- The Old Industrial Waste Lagoon (SWMU 30)
All the SWMUs, including the suspected release sites and other areas requiring environmental evaluation, are described in Table 1.
In March 1993, a large portion of the Industrial Maintenance and Administration Areas of TEAD (total of 1,663 acres) was placed on the BRAC list. In 1996, the Army transferred 40 acres to the Redevelopment Agency of Tooele City (RDA). In January 1999, 1621 acres were transferred to the RDA. In 2002, the remaining 2 acres was transferred directly to the Tooele Federal Credit Union. In March 1995, a report detailing the TEAD conversion and reuse plan was released (HOH Associates, Inc., et al. 1995). Of the 57 SWMU sites identified at TEAD, 23 are located within the BRAC area. Six of these SWMUs are being investigated under CERCLA, with the remainder being investigated under RCRA. The BRAC SWMUs are described in Table 1.
The BRAC property transferred to RDA is being leased to private sector companies for manufacturing and commercial uses in order to improve economic growth in the Tooele area (Rust 1994; US EPA 1991). Since the decision to realign TEAD was made, the Army has adopted several environmental management decisions. As a result of these decisions, BRAC environmental coordination has been assigned to the environmental management division at TEAD and a BRAC cleanup team consisting of TEAD, State of Utah, and EPA Region VIII staff has been established. In addition, a Restoration Advisory Board has been established in an effort to involve the local community in decisions about cleanup priorities (HOH Associates, Inc., et al. 1995).
Several documents have been prepared to evaluate environmental conditions within the BRAC area of TEAD. An environmental baseline survey (EBS) of the entire BRAC area--including a consolidated maintenance facility (CMF) EBS, which focuses on what is considered the most marketable facility within the BRAC area--has been completed. The CMF EBS, which was completed by the environmental management division at TEAD in January 1994, resulted in a finding of "suitability to lease" for the CMF (HOH Associates, Inc., et al. 1995). The finding of "suitability to lease" means that the CMF area has been cleaned to state and federal standards appropriate for the intended land use and is suitable for transfer. In addition, a "Finding of Suitability for Early Transfer" was completed for the 1,700 acres of the BRAC parcel.
As part of the PHA process, the Agency for Toxic Substances and Disease Registry (ATSDR) conducted an initial site visit from April 13 to April 17, 1998. The purpose of the trip was to meet with federal, state, and local environmental and public health officials, as well as concerned community members, to gather information to assist in preparing the PHA. ATSDR revisited the site from January 17 to January 24, 2001, to meet with site representatives, conduct a tour of the site, attend a restoration advisory board meeting, and meet with state and local health officials.
ATSDR conducted two public availability sessions on October 16, 2001. The purpose of these sessions was to meet with local residents of Grantsville and Tooele City to identify their specific health concerns related to living near TEAD. The Community Health Concerns section presents each of the concerns identified by the community members as well as ATSDR's response.
ATSDR released a health consultation in February 1999 which evaluated off site ordnance and explosive waste (OEW) on a privately owned active agricultural crop area. Based on the available information, ATSDR concluded that the potential for detonation, however remote, from the land use could possible result in a health impact.
A PHA is conducted to evaluate potential sources of contamination associated with a site of concern (e.g., a facility placed on the NPL) and identify potential exposure pathways in the surrounding communities. Portions of TEAD, as a result of the Federal BRAC Commission recommendations, have been transferred, either directly to private companies or indirectly through the Tooele City Redevelopment Agency (RDA). Some of the transferred property is currently being used for industrial operations. While other portions are expected to be used for commercial, recreational, or residential purposes. This PHA will address all of the known TEAD contaminated sites, both those that exist on the transferred property and those that exist on the still active portion of TEAD.
As described in the Environmental Contamination and Potential Exposure Pathways section of this PHA, current and projected use of the property greatly influences the current and future potential for community members to be exposed to site-related contaminants. This PHA was conducted assuming that the land use conditions remain as reported in this document. If substantial changes to the land use were considered, it would be important to reevaluate the environmental data (both existing and new data) and determine whether the public health conclusions need to be modified to account for such changes. If requested, ATSDR can reevaluate additional community concerns when new environmental data are available or land use changes indicate that the exposures could be greater than previously described.
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 site and residential areas surrounding TEAD is presented in this section.
As of December 1999, TEAD employed 510 civilian, 2 military, and 163 contractor personnel (Best Manufacturing Survey 1999). There are currently 12 housing units at TEAD located near the front entrance to the depot. Currently these units are leased to a private developer who has managed them as rental property since 1953. TEAD is not directly involved in the day-to-day operations of the housing units. In the past, the average residence time for military personnel stationed in this area and housed in TEAD on-base housing has been approximately 3 years. The Tooele Alternative High School is located in Building 110 at TEAD and has approximately 42 full-time and 100 part-time students. There are no daycare facilities at TEAD (Dames & Moore 1998a; Rust 1997).
Based on the results of the 2000 census, approximately 40,735 persons live in Tooele County. Most of these people (approximately 32,500) live in Tooele Valley, which contains three municipalities: Tooele City (population 22,502), Grantsville (population 6,015), and Stockton (population 443). Tooele County has grown substantially over the past decade (the 1990 population for the county was 26,600) and this trend is expected to continue (Tooele County Chamber of Commerce 2001).
Tooele Valley, located in the Great Salt Lake Basin, is characterized by large fault blocks that form a series of interior basins bounded by mountain ranges. The mountains range in elevation from just under 5,000 feet to over 11,000 feet. The widest part of Tooele Valley faces the Great Salt Lake and it becomes very narrow at the south end where the two mountain ridges almost come together. Salt Lake City is directly east of the Great Salt Lake on the other side of the eastern mountain ridge (Figure 1). Tooele Valley consists of unconsolidated layers of sand, gravel, and clay. Bedrock beneath the sediment layers consists of alternating quartzite and limestone beds (Earth Tech 1995).
Depths to the bedrock at TEAD range from zero, a result of outcrops in the northeast corner, to more than 2,000 feet in the south central portion of the depot. The depths to the bedrock can be several thousand feet within other portions of Tooele Valley. The highest elevation at TEAD is 5,250 feet near the southwestern boundary and the lowest elevation is 4,435 feet at the north central boundary (CES 1991).
Portions of Tooele Valley, along with the rest of Utah, contain rich mineral deposits. Gold, silver, copper, lead, and zinc have been mined from various locations within Tooele County since the late 1800s. Some mining and smelter operations are still active within Tooele Valley. It is possible that soil and groundwater concentrations of metals may be elevated above typical (e.g, average for Tooele County) background concentrations in certain portions of Tooele County as a result of naturally occurring deposits or from historical mining and smelting activities. However, background concentrations of metals measured in groundwater and soil on TEAD property do not indicate unusually high concentrations of metals (Notarianni 2002).
Most of the land around TEAD is agricultural and is used for livestock grazing and limited cultivation. Three types of land uses currently surround TEAD: 1) low-density residential, 2) industrial or manufacturing, and 3) agricultural. Land west and south of TEAD is controlled by the U.S. Forest Service, the U.S. Bureau of Land Management, or Tooele County and is zoned for agriculture, grazing, or mining. Zoning designations to the north are either rural, residential, or agricultural. Zoning designations to the east are generally residential and industrial or manufacturing (TEAD-N 1998).
With the exception of the city of Tooele, the land immediately adjacent and to the east of TEAD is undeveloped. The land to the north is either residential or used as pasture and the land to the west and south is primarily used for rangeland grazing (TEAD-N 1998). In 2001, the city of Grantsville annexed land from Tooele County which extends south to the northern TEAD border. Two new residential subdivisions have been proposed for the new annexed property. One subdivision has been approved by Grantsville and will contain approximately 450 new homes. Another subdivision has been proposed, but not yet approved, for an area just east of the approved 450 home subdivision (Wendy Palmer, City Recorder for Grantsville, Personal Communication, September 5, 2001).
There are no permits for hunting at TEAD. However, controlled cattle grazing is permitted on approximately 20,000 acres of TEAD property from October 15 to May 31 (Rust 1997). A skeet and trap shooting range has been active at TEAD since 1978. Since the range has been active, regulations have been in place to prohibit the use of lead shot at the range. However, the policy was not strictly enforced and lead shot has contaminated some of the soil at the skeet range. As a result of a decline in depot activities, skeet shooting activities decreased in the last few years of operation. Recent activities at the skeet range primarily consisted of occasional shooting competitions and infrequent target practice. The range is currently inactive and there are proposed plans to develop the land for residential use as part of the BRAC process (SAIC 1998).
TEAD is located in the Great Salt Lake Basin, which is part of the Basin and Range Geologic Province. Groundwater flow at TEAD is part of a larger regional groundwater flow system that includes Rush and Tooele Valleys. Groundwater within this system migrates from areas of recharge to areas of discharge. The source of much of the groundwater is from mountain streams and snow melt. The valley is filled with several thousand feet of unconsolidated alluvial sediment underlain by bedrock. Groundwater in Tooele Valley is primarily found in the alluvial valley fill deposits and to a lesser extent in the underlying bedrock. Groundwater underneath TEAD occurs under confined, unconfined, perched, and mounded conditions in either the bedrock or the alluvial aquifers (Ageiss 1994).
In the shallow bedrock aquifer, groundwater flows through fractured sandstone, quartzite, limestone, and dolomite. The depth to the bedrock block containing the shallow aquifer, beneath the eastern portion of TEAD, ranges from the surface layer to around 400 feet below the ground surface. Fractures and weathered rock makeup the groundwater aquifer where the bedrock is shallow. The rate of groundwater movement is primarily controlled by the size and density of fractures within the bedrock, while the orientation of the fracture in the bedrock affects the direction of groundwater movement. The vertical hydraulic conductivity (i.e., the amount of water percolating to the groundwater during a given period of time) in the bedrock aquifer is estimated to range from 2 gallons per day per square foot (gpd/ft2) to 2,000 gpd/ft2 (Kleinfelder 1998b; David Shank, Senior Hydrogeologist, Kleinfelder Inc., personal communication, August 29, 2001).
The alluvial aquifer, which is more than 750 feet thick near the northern boundary of TEAD, is a single aquifer consisting of various sedimentary layers. The aquifer has a wide range of hydraulic conductivity, which was estimated to be from 1 to 5,300 gpd/ft2. Localized perched water zones are present at various depths in the alluvial aquifer and appear to be more prevalent in the central portion of the Tooele Valley (Kleinfelder 1998b).
Groundwater at TEAD is reported to generally migrate from southeast to northwest, flowing towards the center of the valley and eventually toward the Great Salt Lake. Approximately 40 percent of total annual discharge from the groundwater system in the Tooele Valley is through wells. The remaining discharge is attributed to springs, evapotranspiration, and outflow to the Great Salt Lake (CES 1991). Recharge of groundwater primarily occurs along the Tooele Valley margins either as runoff from snow melt or streams or from direct precipitation (David Shank, Senior Hydrogeologist, Kleinfelder Inc., personal communication, August 29, 2001).
There are no major surface water bodies in Tooele Valley. There are five predominant perennial (i.e., permanent) streams or creeks in the valley which originate in the mountains and dissipate as they flow towards the valley floor. Four of the streams originate in the Stansbury Mountains (Davenport, North and South Willow, and Box Elder Canyons) and one flows out of the central Oquirrh Mountains (Settlement Canyon). Water from these streams is usually diverted for irrigation. There are no perennial streams at TEAD itself. Drainage at TEAD typically flows from south to north along natural stream beds and drainage courses during periods of heavy rainfall or rapid snow melt. Water usually is absorbed by soil or vegetation and rarely leaves the depot (Department of the Army 1984). South Willow Creek, which is on the northwestern boundary of TEAD, is the largest of the intermittent streams in the Tooele Valley. Box Elder Wash enters TEAD as an intermittent stream in the southwest portion of the depot. The stream beds located within the depot boundaries are intermittent and carry water from perennial streams originating in the surrounding mountains (Ageiss 1994).
Surface water is not used as a source of drinking water at TEAD or for off-site residential areas. Most of the potable drinking water for the Tooele area comes from deep or intermediate aquifer wells. Potable water at TEAD is drawn from two primary aquifers: 1) the bedrock aquifer and 2) the alluvium aquifer. The depth of potable groundwater underlying TEAD ranges from 200 to greater than 700 feet (Ageiss 1994). Some private residences to the north, northwest, and northeast of TEAD (more than 2 miles away) rely on shallow and intermediate wells for drinking water. Most Tooele and Grantsville residents receive their drinking water from municipal supply wells.
On-Site Drinking Water Wells
TEAD supplies drinking water to approximately 500 employees at the depot. The water supply system originally included a total of four water supply wells, six concrete water storage tanks, and associated water distribution pipelines. The six water storage tanks have a combined storage capacity of 2,375,000 gallons, with the largest tank having a storage capacity of 1,000,000 gallons. Three of the water supply wells are located on the eastern portion of the depot north of the Administration Area (supply wells #1, 2, and 3) and one is located on the southwest portion of TEAD (supply well # 4) (Figure 3). Wells #1, 3, and 4 are currently in operation, however, only two wells, # 1 and 3, are used as a source of potable water. Well #4 is used mainly to provide water for cattle and is not a source of potable water. Ownership of well #2 was transferred from TEAD to the city of Tooele in January 1999. This well has been used by Tooele County for irrigation purposes only. In the summer 2002, TEAD well #2 was used by Tooele County to irrigate a county-operated recreation center. The well was sampled before being used by the county and again 1 month after its initial use. The well was shut down in October 2002. However, Tooele City is interested in resuming use of this well as a source of drinking water for the city (Terracon 1997a; Monty Rashwan, TEAD Engineering, personal communication, April 9, 2001; Gerald Webster, Tooele City Public Works Director, personal communications, October 21, 2002). Two other wells (Wells #5 and 6) have never been connected to the TEAD public water supply system and are currently only used for stock watering. Well #5 is located in the western portion of the Depot and well #6 is located in the Open Revetment Area, approximately 2 miles from the eastern boundary of TEAD (Monty Rashwan, TEAD Engineering, personal communication, April 9, 2001).
Well #1 is drilled to a depth of 763 feet below ground surface (bgs) and the screened interval begins at a depth of 425 feet bgs. The well screen is not continuous and the total screen length is 187 feet. Well #3 is drilled to a total depth of 700 feet bgs and the screened interval begins at a depth of 425 feet bgs. For well #3 the well screen is continuous and the total screen length is 275 feet. Each well has a separate holding tank and the only treatment for the TEAD water system is chlorination (Terracon 1997a, 1997b; Monty Rashwan, TEAD Engineering, personal communication, January 18, 2001). The wells are monitored routinely for bacteriological and chemical contaminants; the monitoring schedule and other monitoring information is outlined in the Drinking Water Source Protection Plan prepared annually for TEAD (Terracon 1997a, 1997b; Monty Rashwan, TEAD Engineering, personal communication, January 18, 2001).
Off-Site Municipal Wells
The city of Tooele draws on 14 municipal wells for its drinking water supply. Four of the fourteen municipal water wells (wells #6, 7, 8, and 9A) are located approximately 1,300 to 1,600 feet to the east of the eastern boundary of TEAD. These wells are screened approximately 1,000 feet bgs. The other municipal wells are not in close proximity to TEAD. There are approximately 24,000 Tooele residents who are served by the municipal drinking water system (Paul Hanson, City Engineer for the Tooele Public Works Department, personal communication, May 4, 2001).
The city of Grantsville, which is located north and northwest of the depot, maintains four municipal wells that serve approximately 5,200 individuals. One of the municipal wells closest to the TEAD boundary (approximately 2,000 feet from the northern boundary), which currently serves about 100 people, is going to provide potable water for new residential developments near the northwest border of the depot. As a result of the new subdivisions, it is estimated, about 1,000 individuals will eventually be served by this well (Joel Kertames, Public Works Director for the City of Grantsville, personal communication, September 5, 2001). The drinking water from these municipal wells is monitored routinely and has met state and federal safe drinking water standards.
Off-Site Private Wells
According to a Toole City public works official, a city ordnance prohibits residents from using private wells for their drinking water supply. Outside of the city limits, however, there are potentially a few private residential wells within 1 mile of the TEAD boundary. Most of the land to the north of the depot is used for agriculture or for livestock and the land to the west, south, and southeast is primarily uninhabited mountainous terrain.
There are some private wells used for irrigation and for livestock north of the TEAD boundary, and one supply well just north of the northeastern boundary of TEAD is used for manufacturing. This supply well, referred to as the Bolinder well, currently provides water to an asphalt manufacturing facility operated by Staker/JB Parsons. The well supplies two small holding tanks of about 10,000 gallons each and pumps at a rate of about 8 gallons per minute. The water from this well is used for industrial operations only and not for drinking or showering (Gary Bolinder, Staker/JB Parsons, personal communication, August 27, 2001; Dames & Moore 1998b).
ATSDR reviewed and evaluated information provided in the referenced documents and databases. Documents prepared for CERCLA and RCRA programs must meet specific standards for adequate quality assurance and control measures for chain-of-custody procedures, laboratory procedures, and data reporting. The environmental data presented in this PHA are from site characterization, remedial investigation, and groundwater monitoring reports or databases prepared by the U.S. Army under CERCLA and RCRA. The validity of the analyses and conclusions drawn in this document are dependent on the availability and reliability of the referenced information. ATSDR reviews data from site-related reports and evaluates whether detection limits are set at levels that are protective of public health. ATSDR also notes any inconsistencies or problems with data collection or reporting and evaluates whether the information is adequate to be used for making public health decisions. From this evaluation, ATSDR determined that the quality of environmental data available for the site-related documents for Tooele Army Depot is adequate to make public health decisions.