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PUBLIC HEALTH ASSESSMENT

HILL AIR FORCE BASE
HILL AIR FORCE BASE, DAVIS AND WEBER COUNTIES, UTAH


TABLES

Table 18.

Evaluation of Operable Units at Hill Air Force Base
Base ID Operable Unit Description Investigation Results/ Environmental Monitoring Results Current Status Evaluation of Public Health Hazard
OU-1 This operable unit (OU) is near the eastern end of the base, east of the main runway, and extends into the city of South Weber. OU-1 is a collection of areas including landfills (LFs) 3 and 4, chemical disposal pits (CDPs) 1 and 2, and firefighter training areas (FTAs) 1 and 2. LF 3 was operated from the early 1940s as a "dump and burn" operation. LF 4 was operated from 1967 to 1973 as a "sanitary landfill" (covered with soil daily) operation. Both landfills received municipal and hazardous waste, including sludge from the Industrial Waste Treatment Plant (IWTP). CDP 1 and 2 were operated from 1954 to 1973 and received liquid wastes, including petroleum products and spent solvents. FTA 1 operated from 1958 to 1973 and was replaced by FTA 2, which is still used today. Until recently, liquid fuel was used to set aircraft on fire. FTA 1 had no lining and unburned fuel was allowed to seep into the ground. FTA 2 was lined with concrete in 1984. Indoor Air: Volatile organic compounds (VOCs), predominantly cis-1,2-dichloroethene (DCE), were found in indoor air in homes in South Weber near the OU-1 groundwater plume. The calculated VOC doses were below levels likely to cause adverse health effects.
Surface Water: Semivolatile organic compounds (SVOCs) and pesticides were found at low levels, generally below acceptable drinking water standards.
Groundwater: There is one groundwater plume in this OU that extends into South Weber. VOCs, primarily cis-1,2-DCE, jet fuel and several metals were detected in the plume at concentrations above acceptable drinking water standards.
Soil: VOCs, polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs) were detected, but generally in areas with limited accessibility. Off-base soil contamination was at or below the water table within areas of the groundwater plume.
A preliminary assessment of OU-1 was conducted in 1982. A remedial investigation (RI) of this OU was conducted in 1994. A Record of Decision (ROD) was completed in 1996. Remedial action construction was performed from 1996-1997, and long-term operation has continued from 1998 to the present. New extraction trenches were installed in 2001 to intercept the plume. Off-base seeps and springs will be evaluated soon. The Performance Standard Verification Plan (PSVP) to evaluate the success of the remediation was written in 2000. ATSDR believes that no public health hazard exists as a result of OU-1. The area is not accessible for direct contact with contaminated soil, and no one is drinking contaminated groundwater from beneath the OU. Indoor air in homes above the plume contains low levels of VOCs that have volatilized from the groundwater plumes. The VOC levels detected are far below those that are known to cause a public health problem.
OU-2 OU-2 is just north of OU-1, near the northeastern end of the base and east of the main runway. This OU extends east into the city of South Weber. The only area within OU-2 is CDP 3. CDP 3 consists of two trenches in which thousands of gallons of solvents were dumped during the 1960s and 1970s. These solvents have pooled on a clay layer 50 feet below the surface. The area may also have received sludge from the plating shop in the 1940s. Contamination associated with CDP 3 was discovered off base in 1986. Indoor Air: No indoor air sampling has been done for the groundwater plume at OU-2. The OU-2 plume is not found beneath any homes.
Surface Water: VOCs, SVOCs and pesticides were found in several springs at levels below those that can cause adverse health effects.
Groundwater: There are two groundwater plumes in this OU. The first is composed of VOCs, primarily TCE, 1,1,1-TCA, and tetrachloroethylene (PCE) that have been detected at concentrations above acceptable drinking water standards and below level associated with health effects in the shallow groundwater aquifer. This plume extends into South Weber. The second is entirely within Hill AFB and consists of dense, non-aqueous phase liquids (DNAPL).
Soil: VOCs, SVOCs, and pesticides were detected, but at or below levels that cause adverse health effects.
A preliminary assessment of OU-2 was conducted in 1982. An RI was completed in 1994, and the ROD was finished in 1996.An interim action (Source Recovery System) of extraction wells in the source area was completed in 1993 and has been continuously operated since then. Additionally, several innovative technology studies are underway to evaluate the potential for more effective cleanup. The PSVP plan to evaluate success of remediation was written in 2001. ATSDR believes that no public health hazard exists as a result of OU-2. The area is not accessible for direct contact with contaminated soil, and no one is drinking contaminated groundwater from beneath the OU.
OU-3 OU-3 consists of soil and surface water in the vicinity of Berman Pond, the Sodium Hydroxide Tank Site (SHTS), the IWTP Sludge Drying Beds, Ponds 1 and 3, and the Refueling Vehicle Maintenance Facility (RVMF) that was at Buildings 511 and 514. Contaminated groundwater that was once included in this OU has been reassigned to OU-8. OU-3 is in the southeast of the base, just west of the main runway and north of the South Gate. Before Hill AFB built the IWTP in 1956, industrial wastewater was dumped into Berman Pond. The pond, which existed from 1940-1956, was filled in and is currently a parking lot. From the late 1950s until 1985, the RVMF (Building 514) was used to maintain aircraft refueling vehicles. The SHTS is the former location of two 12,000-gallon underground storage tanks that were used to store sodium hydroxide. During the period the tanks were used, several hundred gallons of solution were lost due to pipeline leakage. Pond 1 is a storm water retention pond that holds surface water during most of the year. Prior to 1956, Pond 1 was connected to Berman Pond. It reportedly received discharge from Berman Pond from 1940-1941. Pond 3 has been used as a storm water retention pond since 1957. It is currently designated as a wildlife habitat area. Pond 3 receives surface water runoff from the southern area of the base. Surface Water: SVOCs and pesticides were found at levels below those that can cause adverse health effects.

Soil: VOCs, SVOCs, pesticides, and metals were detected, but at or below levels that cause adverse health effects.

A preliminary assessment of OU-3 was conducted in 1982, 1990 and 1991. An RI was completed in 1992 and 1995, and the ROD was finished in 1995. A remedial action design was completed in 1997. Remedial actions were performed from 1997-1998. Ponds 1 and 3 are no further response action planned (NFRAP) areas. The B-514 site was closed in 2001 as NFRAP. The IWTP Sludge Drying Beds were active from 1956-1982 and received sludge materials for temporary storage. The PSVP to evaluate the success of the remediation was written in 2001. ATSDR believes that no public health hazard exists as a result of OU-3. The area is not accessible for direct contact with contaminated soil and surface water.
OU-4 OU-4 consists of a group of areas near the North gate of Hill AFB. OU-4 borders the northeastern boundary of Hill AFB and extends eastward in the cities of Riverdale and South Weber. These areas are LF 1 and 2, the Spoils Pit, the North Gate Dump Site, and the Munitions Dump. LF 1 and 2 received municipal trash between 1955-1967 and 1963-1965, respectively. These landfills might have received hazardous wastes from the Ogden Arsenal. The Spoils Pit received only inert soil and construction debris from 1972-1989. The North Gate Dump Site are believed to have resulted from liquid wastes dumped along the road near the North gate. The Munitions Dump was operated as an above ground storage area during WWII. The North Gate Dump Site, the Munitions Dump, Landfill 2 and the Spoils Pit are now NFRAP areas. Indoor Air: VOCs, including TCE, 1,1,1-TCA, and chloroform were found in indoor air in homes near the OU-4 groundwater plume. The detected VOC levels were below levels likely to cause adverse health effects.
Surface Water: VOCs were found at levels below those which can cause adverse health effects.
Groundwater: There is one groundwater plume in this OU. It is composed primarily of TCE that has been detected at concentrations above acceptable drinking water standards in the shallow groundwater aquifer. This plume extends into South Weber and Riverdale.
Soil: TCE was detected, but at or below levels that cause adverse health effects.
A preliminary assessment of OU-4 was conducted in 1982 and 1990. An RI was completed in 1993, and the ROD was finished in 1994. A remedial action design was completed in 1999. Remedial actions are currently ongoing. The North Gate Dump Site, the Munitions Dump, Landfill 2 and the Spoils Pit are now NFRAP areas. A geosystem review is underway to evaluate the efficacy of required treatment. The airstripper was bypassed in 2001 because influent concentrations fell below the regulatory limit. The PSVP to evaluate the success of the remediation was written in 2001. Hybrid poplars have been planted to evaluate the effect on attenuation of TCE. ATSDR believes that no public health hazard exists as a result of OU-4. The area is not accessible for direct contact with contaminated soil, and no one is drinking contaminated groundwater from beneath the OU. Indoor air is contaminated with low levels of VOCs that have volatilized from the groundwater plumes. The VOC levels detected are far below those that are known to cause a public health problem.
OU-5 OU-5 is on the western side of Hill AFB and extends westward into the communities of Sunset and Clinton. OU-5 consists of two areas: the Tooele Army Rail Shop (TARS) and Zone 16. TARS was constructed in 1942 to support the Ogden Army Arsenal and upgraded in 1944 to service and repair railroad engines for the military. An open area west of the Rail Shop was used for cleaning large train parts, and residual fluids were allowed to drain onto the ground. Solvents, petroleum products, and sodium cyanide solutions were reportedly used at this location. TCE was reportedly used from 1949 to 1964. Prior to 1979, runoff from steam cleaning operations flowed into a drainage gate and connected drain lines which led to an in-ground oil-water separator. Excavations for Building 1712 revealed that the oil-water separator was ineffective and some runoff had drained to the ground west of the steam-cleaning area. The Zone 16 area is series of buildings that are currently used from munitions and missile storage and rocket motor testing. Zone 16 was constructed in about 1940 and was originally used for munitions and fuse manufacturing. A flash pond (no longer in use) immediately south of building 1607 is an area that was presumably used for disposal of small quantities of liquid waste materials. After WWII this area was converted to missile/rocket testing and storage. Indoor Air: VOCs, including TCE, TCA and chloroform were found in indoor air in homes in vicinity of the OU5 groundwater plume, but at concentration that would not be considered hazardous.
Surface Water: VOCs were found at levels below those which can cause adverse health effects.
Groundwater: At OU 5 there are two groundwater water contamination plumes (known as the TARS and Zone 16 plumes) migrating from on-base source areas into the communities of Sunset and Clinton. These two plumes are primarily composed of TCE and contain concentrations that are above levels set by the EPA as being acceptable in drinking water. The TARS plume extends close to 5000 feet off base and covers 113 acres while the Zone 16 plume extends more than 7000 feet off base and covers 236 acres.
Soil: Lead, total petroleum hydrocarbons (TPH) and arsenic were detected on-base at or below levels that cause adverse health effects. Soil contamination in these communities is not an issue for this investigation.
A preliminary assessment of OU-5 was conducted in 1989. A remedial investigation was completed in 1995. However, additional source areas and groundwater contamination were identified in 1998, and as a result, the RI was reopened and is continuing at this time. The RI will be completed in 2003. Two early remedial actions were installed in 1996 and 1997 in the TARS and a third will be installed and operating by spring of 2003. ATSDR believes that no public health hazard exists as a result of OU-5. The area is not accessible for direct contact with contaminated soil, and no one is drinking contaminated groundwater from beneath the OU. Indoor air in homes above the plume contains low levels of VOCs that have volatilized from the groundwater plumes. The VOC levels detected are far below those that are known to cause a public health problem.
OU-6 OU-6 is on the northern side of Hill AFB. It extends northward into the community of Riverdale. OU-6 was created following the discovery of contamination in the Craigdale subdivision of Riverdale. OU-6 consists of two areas: Building 1915 and the 2000 (Asphalt Pad) Area. Building 1915 was active from 1959 to 1985 as a fuel and waste sludge storage facility and a suspected leach field. The 2000 (Asphalt Pad) Area is an active Class 4 landfill used for clean fill sods and concrete. During the investigation, this area was ruled our as a potential sources area. The buildings to the south in the MAMS II area were identified as the probable source via soil gas, soil samples, and groundwater data. Indoor Air: VOCs, including TCE, TCA, and chloroform were found in indoor air in homes above the OU-6 groundwater plumes at levels below levels causing adverse health effects in laboratory studies.
Surface Water: VOCs were found at levels below those that can cause adverse health effects.
Groundwater: There are two groundwater plumes as a result of contamination from this OU. They are composed primarily of TCE that has been detected at concentrations above acceptable drinking water standards in the shallow groundwater aquifer.
Soil: Dichloroethene (DCE) has been the primary contaminant detected, but at or below levels that cause adverse health effects.
A preliminary assessment of OU-6 was conducted in 1989 and 1990. A base investigation was finished in 1992 and a RI was completed in 1995. Interim remedial actions were instituted in 1996 and a ROD was done in 1997. The Remedial Design was completed in 1998 with actions performed in 1999. The installation of the on-base extraction system has resulted in a very significant reduction in groundwater flow off-base to the Cooley treatment system. The airstrippers at the both Craigdale and Cooley system will be bypassed in 2002 because influent concentrations have dropped below regulatory limits. The PSVP to evaluate success of remediation was written in 2001. Hybrid poplars have been planted to evaluate effect on attenuation of TCE. ATSDR believes that no public health hazard exists as a result of OU-6. The area is not accessible for direct contact with contaminated soil, and no one is drinking contaminated groundwater from beneath the OU. Indoor air in homes above the plume contains low levels of VOCs that have volatilized from the groundwater plumes. The VOC levels detected are far below those that are known to cause a public health problem.
OU-7 OU-7 is in the southeastern area of Hill AFB. OU-7 is a collection of areas in the base's industrial complex and consists of only soil. The primary sources are Buildings 220 and 225. Building 225 housed an electroplating shop. During its operation, chromic acid leaked into the soil beneath the building. In another area of the building, PCBs leaked from a transformer and contaminated soil beneath the building. The contamination was discovered in 1989. In Building 220, underground storage tanks were used to collect paint stripping wastes. Apparently, pipes leading to these tanks leaked some of the solvents and wastes into the soil beneath the building. Soil: Cadmium and hexavalent and total chromium have been found in soil in the OU-7. The contaminated soil is beneath Building 225, which serves as the primary maintenance hangar. A preliminary assessment of OU-7 was conducted in 1988, 1989 and 1990. A base investigation was finished in 1994 and a RI was completed in 1995. A ROD was done in 1995. The Remedial Design was completed in 1996 with actions performed in 1997. The PSVP to evaluate success of remediation was written in 2001. ATSDR believes that no public health hazard exists from OU-7. The area is not accessible for direct contact with contaminated soil.
  OU-8 is in the southern area of Hill AFB and extends south into the cities of Layton and Clearfield. OU-8 was established in 1993 as part of a plan to consolidate all groundwater contamination under the base's industrial complex. It focuses on groundwater that was discovered during the investigations into OU3 and OU7. Indoor Air: Limited sampling data suggest that VOCs, including TCE, TCA, and chloroform were found in indoor air in homes near the OU-8 groundwater plume at levels below levels causing adverse health effects in laboratory studies.

Groundwater: There is one groundwater plume as a result of contamination from this OU. It is composed primarily of TCE that has been detected at concentrations above the acceptable drinking water standards in the shallow groundwater aquifer.

A preliminary assessment of OU-8 was conducted in 1988, 1989 and 1990. A base investigation began in 1988 and is still on-going. Interim remedial actions began in 1997 and are still underway. A RI was completed in December 2001. ATSDR believes that no public health hazard exists as a result of OU-8. The area is not accessible for direct contact with contaminated soil, and no one is drinking contaminated groundwater from beneath the OU. Indoor air in homes above the plume contains low levels of VOCs that have volatilized from the groundwater plumes. The VOC levels detected are far below those that are known to cause a public health problem. Continued indoor air sampling is recommended for homes in Layton and Clearfield.
OU-9 OU 9 investigations began in 1993 when it was realized that there was significant potential for additional unidentified sources, other than those previously identified as part of OU 3 and OU 7, which were contributing contamination to the groundwater beneath the main base industrial area. The initial investigation was eventually expanded to cover the rest of the base in those areas not previously investigated as part of an existing OU. Many of the areas of investigation are in the vicinity of actively used buildings where complete characterization is not possible. These are referred to as deferred sites. The plan is that the investigation process will continue when access becomes available in the future. Currently, there are 180 sites in this category. If a site is found with significant contamination in soils and or groundwater where the groundwater is not already part of another OU, then the option exists for the site (soil and groundwater) to become a new OU. OU 9 also includes Ponds 1 and 3, which are used as storm water retention basins. OU-9 is a soils-only OU. Soil: Petroleum products, PCBs, and pesticides have been detected in soil near Buildings 43 and 45. These have been found at levels below that which cause adverse health effects. A Preliminary Assessment for OU 9 was begun in 1993. Field investigations consisting of soil sampling began in 1995 and continue as sites become accessible. Pond 1 is scheduled for remedial action during the summer and fall of 2002. Pond 3 is currently undergoing field investigation work. Site B-870 and B-914 have been remediated and are under long-term monitoring. Bioventing at site 43 was started in 2002, and a soil vapor extraction system has been installed at site 454. ATSDR believes that no public health hazard exists as a result of OU-9. Access to the areas of contaminated soil is limited.
OU-10 OU-10 consists of groundwater contamination beneath the 1100, 1200 and Defense Reutilization Marketing Office (DRMO) area buildings on base and groundwater contamination off base beneath the cities of Sunset and Clearfield. Groundwater: Groundwater contamination has been detected in OU-10. The primary contaminant is TCE, which has been detected at concentrations above acceptable drinking water standards in the shallow groundwater aquifer. The initial investigation has been completed at the DRMO and 1100 area plumes, but is continuing in the 1200 area on base and in the cities of Sunset and Clearfield. Although contamination is present in OU-10, ATSDR believes that no public health hazard exists. No one is drinking contaminated groundwater from beneath the OU.
OU-11 OU-11 consists of soil and groundwater contamination at former Building 454 and the Base Golf Course near Building 710. OU-11 also consists of the building 800 area where groundwater contamination has been discovered. Soils contamination (solvents, etc.) has not been found at OU-11 other than fuels residuals at Building 454, which is being addressed under the UST program separate from OU-11. Groundwater: VOCs, primarily TCE, have been detected in the shallow aquifer at levels above acceptable drinking water standards. A remedial investigation is on-going. ATSDR believes that no public health hazard exists from OU-11. No one is drinking contaminated groundwater from beneath the OU and access to the areas of contaminated soil is limited.
OU-12 OU-12 is located in an open area of the base, just northwest of the former wastewater treatment plant. It consists of soil and groundwater contamination. The source of contamination at OU-12 appears to be related to miscellaneous dumping of drums containing waste solvents and sludges at several locations in a 2-3 acre area. The source area is currently known as the Aspen Avenue Disposal site. The date(s) when this dumping occurred is completely unknown and is thought to have happened prior to the mid 1970s. Minor amounts of another solvent, carbon tetrachloride, have also been detected in the groundwater near this location and are thought to have originated from activities related to the former wastewater treatment plant. Indoor Air: TCE was found in indoor air samples in 7 of more than 80 homes sampled. The concentrations range from ND to 16 ppbv. The indoor air detections are all located near the toe of the OU-12 groundwater contamination plume where groundwater is very shallow and TCE concentrations at the water table are relatively high.
Groundwater: The OU12 groundwater contamination plume is primarily composed of TCE and contains concentrations that are above levels set by the EPA as being acceptable in drinking water. The OU-12 plume extends more about 8,500 feet off base and covers a little more than 100 acres.
The remedial investigation began in 2000 and will continue through 2003. An early remedial action is currently being constructed at the base boundary and will be completed in fall 2002. This cleanup system is designed to cut off the migration of contaminants off of Hill AFB. Another early action for the toe area of the plume is in the planning stages. A groundwater extraction well system is planned for installation at the base boundary in 2002. ATSDR believes that no public health hazard exists from OU-12. No one is drinking contaminated groundwater from beneath the OU. Indoor air...
Utah Test and Training Range The Utah Test and Training Range (UTTR) is in northwestern Utah and eastern Nevada. It is contained within the Great Salt Lake Desert, approximately 70 miles west of Salt Lake City. Mission Control facilities are off-range at Hill AFB. Several activities performed at UTTR have caused contamination. The Herbicide Orange Test was done from 1972-1974. As a result, herbicide testing has impacted shallow and surface soils. The Test and Training Unit (TTU) Disposal Trenches/EOD Burn Site was active from the 1940s to the 1980s. The trenches were used for disposal of ordnance, missile motors, and munitions residues from detonations and/or burns. Chemical Disposal Pit 4 is at UTTR. CDP 4 was active from 1973-1975 as a location for waste oil, solvents, and diesel fuel disposal. There are several other areas of possible contamination at UTTR. These include the fire training area, sewage lagoons, surface impoundments, and dumps. Soil: Only soil contamination has been suspected or identified. No exposure information has been obtained. Contaminants of concern are being evaluated under preliminary assessment/base inspection programs.

Investigations are ongoing. Remedial activities to be determined.

ATSDR believes that no public health hazard exists from UTTR. UTTR is highly restricted. As such, no access by individuals without authorization is expected.
Little Mountain Test Annex The Little Mountain Test Annex is on the northeastern border of the Great Salt Lake, north of Hill AFB. There are two areas of concern at the Little Mountain Test Annex. The Sludge Drying Beds were operated from 1958 to the 1970s. The drying beds consisted of two shallow unlined pits that received industrial wastes from engine testing and missile hardness testing operations. In the 1960s, the beds received water from the adjacent water treatment plants. In the 1970s, the beds received phenolic paint strippers from Hill AFB. The Magnesium-Thorium Scrap Material Disposal Area was operated from 1958 to the 1970s as a receipt point for scrap material from the manufacture of thorium-painted navigational dials. Surface soil: Metals and SVOCs have been detected in surface soil and residual sludge.
Solids: The bedrock underlying the sludge drying beds is contaminated with VOCs and SVOCs. Bedrock occurs between 3 and 10 feet below ground surface.
Groundwater: Groundwater is contaminated with VOCs (mainly TCE, DCE, acetone, and methylene chloride). Some SVOC and TPH contamination is also present.
Remedial investigations of the Sludge Drying Beds began in 1988 and were completed in 1990. The remedial investigation into the beds was reopened in 1998 to investigate the nature and extent of contamination. The Magnesium-Thorium Scrap Material Disposal Area is not an IRP area. It was investigated from 1993-1994. It currently is a NFRAP area. A fence has been installed and institutional controls implemented. ATSDR believes that no public health hazard exists from Little Mountain Test Annex. Little Mountain Test Annex has security and gates restricting access.
Wendover Field Wendover Air Force Auxiliary Field consists of a landfill and other maintenance facilities. It has been in operation since the 1940s. Contamination suspected at the area includes solid waste, spent munitions, waste solvents, and suspected ordnance. In August 1961 the Air Force inactivated Wendover Air Force Auxiliary Field, with Hill AFB assigned "caretaker status" for the installation. Then in August 1977 Hill AFB turned over most of Wendover Air Force Auxiliary Field to the town of Wendover, Utah, retaining only a 164-acre radar area on the old base. Groundwater: Benzene contamination has been detected.

Soil: Trace organics and metals have been detected. Additionally, unexploded ordnance poses a problem.

Investigations were conducted from 1992-1994. None of 18 areas at Wendover present a quantifiable risk. Long-term groundwater monitoring has been on-going since 1995. Currently, only long term monitoring is planned. ATSDR believes that no public health hazard exists from Wendover Air Force Auxiliary Field. Wendover Air Force Auxiliary Field is highly restricted. As such, no access by individuals without authorization is expected. Additionally, Wendover Air Force Auxiliary Field is outside the current range boundary for Hill AFB and falls under the Corps of Engineers Formerly Used Defense Sites (FUDS) program.

Key:

ATSDR = Agency for Toxic Substances and Disease Registry
CDP = Chemical Disposal Pit
DCE = dichloroethene
DNAPL = dense, non-aqueous phase liquid
EPA = Environmental Protection Agency
FTA = Fire Training Area
Hill AFB = Hill Air Force Base
IWTP = Industrial Waste Treatment Plant
LF = landfill
MCL = Maximum Contaminant Level
NFRAP = no further response action planned
OU = operable unit
PAHs = polycyclic aromatic hydrocarbons
PCBs = polychlorinated biphenyls
PCE = tetrachloroethene
RI = remedial investigation
RVMF = Refueling Vehicle Maintenance Area
SHTS = Sodium Hydroxide Tank Site
SVOCs = semivolatile organic compounds
TARS = Tooele Army Rail Shop
TCA = 1,1,1-trichloroethane
TCE = trichloroethene
TPH = total petroleum hydrocarbons
UST = underground storage tank
UTTR = Utah Test and Training Range
VOCs = volatile organic compounds


Table 19.

Exposure Pathways Table
Pathway Name Exposure Pathway Elements Comments
Source of Contamination Environmental Medium Point of Exposure Route of Exposure Potentially Exposed Population
Completed Exposure Pathway
Inhalation of Indoor Air Contaminants Organic compounds in groundwater plumes from Hill AFB have volatilized and seeped into basements of homes in the on-base Patriots Hill Housing area and in homes in adjacent communities of Sunset, Clinton, Roy, Layton, Clearfield, Riverdale, and South Weber Indoor Air Homes in the on-base Patriots Hill Housing Area and homes in the communities of Sunset, Clinton, Roy, Layton, Clearfield, Riverdale, and South Weber Inhalation Certain residents of the Patriots Hill Housing area, as well as certain residents of Sunset, Clinton, Roy, Layton, Clearfield, Riverdale, and South Weber Past, Current, Future: People who live in homes above the groundwater plumes may have been exposed to low levels of contaminants that have volatilized from the plumes. Tests have shown that the contaminants exist in tested homes, but at levels generally below nationwide means and below levels associated with adverse health effects. Continued indoor air monitoring is planned for Roy and is recommended for Layton, Clearfield because of limited, preliminary sampling.
Potential Exposure Pathways
Groundwater Hill AFB activities have affected groundwater underlying the base contaminants, primarily volatile organic compounds (VOCs), Groundwater None. Groundwater underlying Hill AFB or in the areas of the plumes has never been used as a source of public drinking water supplies. None. None. Past, Current and Future: Residents of Hill AFB receive their water from base water supply and neighboring communities receive drinking water from municipal sources. These supplies obtain water from the deep, uncontaminated aquifers. Suppliers also conduct test to ensure that the water meets federal (i.e., EPA's maximum contaminants levels) and state drinking water standards. No private wells in the area are used for drinking water.
Surface Soil Hill AFB activities have contaminated on-base soil. Contaminants include VOCs, metals, polycyclic aromatic hydrocarbons and polychlorinated biphenyls (PCBs). Exposure to contaminated soil at other Hill AFB IRP areas is largely prevented because the majority of the area is inaccessible and/or lie in restricted land use locations. Soil Surface soil at Hill AFB IRP areas Dermal contact and incidental ingestion Hill AFB personnel and base residents Past: People may have contacted low levels of contaminants in surface soil. Sporadic contact with or incidental ingestion of the contaminants detected in the surface soil is not expected to have resulted in harmful effects.

Current and Future: No public health hazards are occurring or are expected to occur.

Surface Water Hill AFB IRP areas and possibly other nonpoint and point sources. Contaminants include primarily PCBs in sediment, but also PAHs and metals. Surface water Area irrigation canals, seep, or springs. Dermal contact and incidental ingestion People trespassing into the canals. Past, Current, and Future: No apparent public health hazard is expected for this pathway. The canals are not used for drinking water nor widely accessed. Sporadic contact with contaminants at the levels detected in the surface water in the canals, seeps, or springs are not expected to result in adverse health effects.
Consumption of Locally-Grown Fruits and Crops Contaminants from Hill AFB that have entered irrigation canals or private wells used for irrigation Locally-grown crops Locally-grown crops Ingestion Residents of Hill AFB, Sunset, Clinton, Roy, Riverdale, Layton, Clearfield, and South Weber Past, Current, and Future: No apparent public health hazard is expected for this pathway. Tests have shown that locally grown and irrigated crops do not take up contaminants at levels that could be harmful to consumers.


Table 20.

Patriot Hills Housing Area Estimated Indoor Air Exposure Dose and Health-Guidance Levels
  Moleculr Weight Maximum Concentration (ppb) Maximum Concentration (mg/m3) Ambient Air RBC (mg/m3) Effect EPAs Reference Dose (mg/kg/day) Estimated Noncancer Dose-max (mg/kg/day) ATSDR Conclusion for Based on Ambient Air RBC-max ATSDR Conclusion for Noncancerous Health Effects-max Estimated Cancer Dose-max (mg/kg/day) Cancer Slope Factor Cancer Risk Estimate-max ATSDR Conclusion for Cancer Risk-max LOAEL (ppb)
In-Home Measurements
Benzene 78.1134 2 0.00639 0.00022 C 0.0017 0.00182561   Investigate Further 0.0008 0.0290 2.3E-05 No hazard 780
Toluene 92.1402 10.05 0.03787 0.42 N 0.1140 0.01082102   No hazard          
Ethyl Benzene 106.167 0.85 0.00369 1.1 N 0.2900 0.00105454   No hazard          
m,p-xylenes 212.334 3.2 0.02779 7.3 N   0.00794004 * *          
o-Xylene 106.167 1.73 0.00751 7.3 N   0.00214629 * *          
Xylenes 318.501 4.93 0.0353 7.3 N   0.01008633 No hazard            
Flux Measurement
Benzene 78.1134 18 0.05751 0.00022 C 0.0017 0.01643051   Investigate Further 0.0070 0.0290 0.0002 Investigate Further 780
Toluene 92.1402 43 0.16205 0.42 N 0.1140 0.0462989   No hazard          
Ethyl Benzene 106.167 0.5 0.00217 1.1 N 0.2900 0.00062032   No hazard          
Xylene 106.167 2.17 0.00942 7.3 N   0.00269217 No hazard            
Indoor Air Modeling
Benzene   0.5 0 0.00022 C 0.0017 0   No hazard 0.0000 0.0290 0 No hazard 780

N - Noncancerous
C - Cancerous
RBC - Risk Based Concentration
LOAEL - Lowest Observed Adverse Effect Level
ppb - parts per billion
* - Results combined to form total xylenes


Table 21.

Sunset, Clinton, and Roy Estimated Indoor Air Exposure Doses and Health-Guidance Levels
  Maximum Concentration (ppb) Maximum Concentration (mg/m3) Ambient Air RBC (mg/m3) Effect EPAs Reference Dose (mg/kg/day) Estimated Noncancer Dose-max (mg/kg/day) ATSDR Conclusion for Noncancerous Health Effects-max Estimated Cancer Dose-max (mg/kg/day) Cancer Slope Factor Cancer Risk Estimate-max ATSDR Conclusion for Cancer Risk-max NOAEL (ppb) LOAEL (ppb)
Sunset and Clinton
TCE 2.95 0.0159 0.001 C 0.006000 0.004529 No hazard 0.0019 0.0060 1.16E-05 No hazard   50000
TCA 7.95 0.0434 0.420 N 0.630000 0.012393 No hazard         70000  
Chloroform 1.1 0.0054 0.0001 C 0.000086 0.001535 Investigate Further 0.0007 0.0810 5.33E-05 No hazard   2000
Vinyl Chloride 1.8 0.0046 0.0001 C 0.028000 0.001315 No hazard 0.0006 0.0300 1.69E-05 No hazard   100000
Roy
TCE - first round 13 0.0701 0.001 C 0.006000 0.020036 Investigate Further 0.0086 0.0060 5.15E-05 No hazard   50000
TCE - second round 3 0.0162 0.001 C 0.006000 0.004624 No hazard 0.0020 0.0060 1.19E-05 No hazard   50000

N - Noncancerous
C - Cancerous
RBC - Risk Based Concentration
LOAEL - Lowest Observed Adverse Effect Level
NOAEL - No Observed Adverse Effect Level
ppb - parts per billion


Table 22.

Layton Estimated Indoor Air Exposure Doses and Health-Guidance Levels
  Maximum Concentration (ppb) Maximum Concentration (mg/m3) Ambient Air RBC (mg/m3) Effect EPAs Reference Dose (mg/kg/day) Estimated Noncancer Dose (mg/kg/day) ATSDR Conclusion Based on Ambient Air RBC ATSDR Conclusion for Noncancerous Health Effects Estimated Cancer Dose (mg/kg/day) Cancer Slope Factor Cancer Risk Estimate ATSDR Conclusion for Cancer Risk LOAEL (ppb)
Layton 1997
Acetone 11 0.02613 0.3700 N   0.007466 No hazard            
Benzene 6 0.019169 0.0002 C 0.001700 0.005477   Investigate Further 0.0023 0.0290 0.000068 No hazard 780
Toluene 14 0.052759 0.4200 N 0.114000 0.015074   No hazard          
Xylenes 9.5 0.066152 7.3000 N   0.0189 No hazard            
TCE 2.2 0.011822 0.0010 C 0.006000 0.003378   No hazard 0.0014 0.0060 0.000009 No hazard 50000
Layton 2000
TCE 0.32 0.00172 0.0010 C 0.006000 0.000491   No hazard 0.0002 0.0060 0.000001 No hazard 50000
Vinyl Chloride 0.45 0.00115 0.0001 C 0.028000 0.000329   No hazard 0.0001 0.0300 0.000004 No hazard 100000
Chloroform 6.3 0.03076 0.0001 C 0.000086 0.008789   Investigate Further 0.0038 0.0810 0.000305 Investigate Further 2000
1,2-DCA 0.12 0.000486 0.0001 C 0.0014 0.000139   No hazard 0.0001 0.0910 0.000005 No hazard  

N - Noncancerous
C - Cancerous
RBC - Risk Based Concentration
LOAEL - Lowest Observed Adverse Effect Level
ppb - parts per billion


Table 23.

Riverdale Estimated Indoor Air Exposure Doses and Health-Guidance Levels
  Maximum Concentration (ppb) Maximum Concentration (mg/m3) Ambient Air RBC (mg/m3) Effect EPAs Reference Dose (mg/kg/day) Estimated Noncancer Dose-max (mg/kg/day) ATSDR Conclusion for Noncancerous Health Effects-max Estimated Cancer Dose-max (mg/kg/day) Cancer Slope Factor Cancer Risk Estimate-max ATSDR Conclusion for Cancer Risk-max NOAEL (ppb) LOAEL (ppb)
                           
TCE 0.65 0.003493 0.001 C 0.006000 0.000998 No hazard 0.0004 0.0060 2.57E-06 No hazard   50000
TCA 41.35 0.225615 0.420 N 0.630000 0.064462 No hazard         70000  
Chloroform 5 0.024413 0.0001 C 0.000086 0.006975 Investigate Further 0.0030 0.0810 0.000242 Investigate Further   2000

N - Noncancerous
C - Cancerous
RBC - Risk Based Concentration
LOAEL - Lowest Observed Adverse Effect Level
NOAEL - No Observed Adverse Effect Level
ppb - parts per billion


Table 24.

South Weber Estimated Indoor Air Exposure Doses and Health-Guidance Levels
  Maximum Concentration (ppb) Maximum Concentration (mg/m3) Ambient Air RBC (mg/m3) Effect EPAs Reference Dose (mg/kg/day) Estimated Noncancer Dose (mg/kg/day) ATSDR Conclusion for Based on Ambient Air RBC ATSDR Conclusion for Noncancerous Health Effects Estimated Cancer Dose (mg/kg/day) Cancer Slope Factor Cancer Risk Estimate ATSDR Conclusion for Cancer Risk NOAEL (ppb) LOAEL (ppb)
1990
TCA 0.004 2.18E-05 0.420 N 0.630000 6.24E-06   No hazard            
1993
TCE 0.74 0.003977 0.001 C 0.006000 0.001136   No hazard 0.0005 0.0060 0.000003 No hazard   50000
TCA 18 0.098212 0.420 N 0.630000 0.028061   No hazard         70000 100000
Chloroform 0.23 0.001123 0.000 C 0.000086 0.000321   Investigate Further 0.0001 0.0810 0.000011 No hazard   2000
1994-1995
TCE 0.4 0.00215 0.001 C 0.006000 0.000614   No hazard 0.0003 0.0060 0.000002 No hazard   50000
TCA 0.89 0.004856 0.420 N 0.630000 0.001387   No hazard         70000 100000
Chloroform 0.08 0.000391 0.000 C 0.000086 0.000112   Investigate Further 0.0000 0.0810 0.000004 No hazard   2000
cis-1,2-DCE 0.29 0.00115 0.037 N   0.000329 No hazard              

N - Noncancerous
C - Cancerous
RBC - Risk Based Concentration
LOAEL - Lowest Observed Adverse Effect Level
NOAEL - No Observed Adverse Effect Level
ppb - parts per billion


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