PUBLIC HEALTH ASSESSMENT
BOOMSNUB/AIRCO SUPERFUND SITE
(a/k/a BOOMSNUB/AIRCO)
VANCOUVER, CLARK COUNTY, WASHINGTON
The Boomsnub/Airco Superfund site is located in the south end of Hazel Dell, Washington, an unincorporated town in Clark County, Washington. The site consists of the former Boomsnub chrome plating facility where a number of chromium releases occurred to soil and groundwater; BOC Gases (formerly Airco), a gas manufacturing facility where volatile organic compound releases occurred to soil and groundwater; and a commingled plume of metals (primarily chromium) and volatile organic compounds in groundwater within the shallow, Alluvial aquifer and to a lesser extent in the deeper, Upper Troutdale aquifer.
The Washington State Department of Health (WDOH) conducted a public health assessment for the site in 1995 and determined that the site was a public health hazard because it posed a threat to the municipal water supply which draws water from the Upper Troutdale aquifer. WDOH also determined that the Boomsnub facility, prior to its closure in 1994, represented a health hazard to site workers exposed to chromium. As a result of its findings, WDOH made a number of recommendations: reduce or prevent exposure to contaminants; identify sources of contamination; and educate the public about the health implications of the site.
Since 1995, additional soil and groundwater data were collected at the site by the U.S. Environmental Protection Agency (EPA) and BOC Gases. WDOH evaluated this new data as part of an earlier draft of this public health assessment.
Surface soil at the Boomsnub and adjacent properties was further investigated by EPA as part of a remedial investigation at the site. Although a number of metals and organic compounds were detected, the concentrations of the chemicals in surface soil pose no apparent public health hazard.
Subsurface soil investigations were also conducted since 1995 at the Boomsnub and BOC Gases properties. Elevated concentrations of volatile organic compounds were detected in subsurface soil and soil gas at the BOC Gases property. Metals and some organic compounds were detected in subsurface soils at the Boomsnub and adjacent properties and some volatile organic compounds were also detected in soil gas. No one is currently being exposed to these subsurface contaminants and therefore, no health threat exists.
A groundwater pump and treatment system has operated in the shallow Alluvial aquifer at the site since 1990 to treat the chromium and volatile organic contaminated groundwater. Although the chromium and volatile organic compound concentrations have been reduced as a result of the pump and treatment system, the contaminant plume still poses a threat to private wells in the shallow aquifer. The plume also poses a threat to the municipal water supply wells located in the underlying, deeper Upper Troutdale aquifer. The municipal wells serve approximately 135,000 people in the City of Vancouver as well as 22,000 homes in Hazel Dell and other unincorporated areas north of Vancouver.
Metals (primarily chromium), and volatile organic compounds have also been detected at low levels at some monitoring wells and water supply wells in the deeper, Upper Troutdale aquifer in an area that extends downgradient of the BOC Gases and Boomsnub properties. The boundaries of the groundwater contamination in the Upper Troutdale aquifer, however, have not been determined. The detected contaminants pose a potential threat to private wells in the Upper Troutdale aquifer.
The site continues to be a public health hazard because of the groundwater contamination. As a result, WDOH recommends that a number of actions be taken at the site: boundaries of the groundwater contamination in the Alluvial and Upper Troutdale aquifers should continue to be defined; groundwater contaminants should be prevented from spreading further; and groundwater and soil contaminant concentrations should be eliminated or reduced to levels that are protective of human health. WDOH also recommends that abandoned wells in or close to the identified paths of the contaminated groundwater and public and private wells located within and near the areas of contaminated groundwater be closely monitored. A door-to-door survey should be conducted to identify all existing wells in the areas of contaminated groundwater within the Alluvial and Upper Troutdale aquifers. Wells within areas of contaminated groundwater that act as channels for transmitting contaminants should be eliminated.
The Washington State Department of Health (WDOH) has prepared this public health assessment in response to new soil and groundwater data collected at the Boomsnub/Airco Superfund site since 1995 when WDOH conducted its initial public health assessment. The new information was used to further evaluate the health hazards associated with the site.
Groundwater in the vicinity of the site serves as a public and private water supply source. The potential impacts of the site contamination on groundwater remain a significant health concern for the community and the local public water suppliers. Worker exposure to contaminated soils is also a health concern raised by some site workers.
2.1. Site Description and History
The Boomsnub/Airco Superfund site is located in Hazel Dell, an unincorporated town, in Clark County, Washington. The site consists of the Boomsnub and BOC Gases properties which are located south of the intersection of NE 47th Avenue and NE 78th Street as well as two areas of groundwater contamination that extend west of NE 47th Avenue (Figure 1).
The former Boomsnub facility was located on less than 1 acre of land; BOC Gases occupies approximately 11 acres. Boomsnub, a relatively flat property, is bordered by a railroad right-of-way to the west; commercial businesses or light industry to the north and south; and NE 47th Avenue to the east. BOC Gases, also a relatively flat property, is bordered by NE 47th Avenue and NE 78th Street to the west and north, respectively; a light industry to the south; and an industrial and residential area to the east.
Boomsnub operated a chrome plating facility at the property from 1967 to June 1994. During its operation, a number of chromium releases occurred that resulted in the contamination of soil and, ultimately, groundwater. Sources of chromium contamination included spills and leaks of chromic acid from an above-ground storage tank, plating pits, and concrete lined floor pits.1, 2 The Washington State Department of Ecology (Ecology) began investigating the chromium contamination at the Boomsnub property in 1987 and installed a groundwater treatment system in the uppermost aquifer at the property in 1990 to collect and remove chromium. Volatile organic compounds were detected by Ecology during its operation of the system. The groundwater treatment system was expanded to treat the additional contaminants.1, 2
BOC Gases, a compressed and liquified gas manufacturing and distributing facility that began operating in 1964, was the suspected source of the volatile organic contamination. BOC Gases began soil and groundwater investigations at its property in 1991. Volatile organic contaminated water and sediment were discovered in a dry well on BOC Gases' property during the investigations. The dry well, located above the Alluvial aquifer, was a shallow well that was used for waste water and storm water infiltration. Water and sediment were removed in March 1994 because they were the likely sources for the volatile organic compounds detected in groundwater.2
In June 1994, the Environmental Protection Agency (EPA) took over as the lead regulatory agency for the Boomsnub/Airco site. EPA excavated and removed approximately two-thirds of the chromium-contaminated soils from the Boomsnub property.2 The removal action was completed in late 1994.
Because of the continuing movement of the contaminant plume in the shallow, Alluvial aquifer and concerns about the quality of the groundwater being used by private well owners in or near the plume, WDOH, in cooperation with the Southwest Washington Health District, the Department of Ecology, the City of Vancouver, Clark Public Utilities, and the EPA issued a news release in July 1994 advising residents who were using private wells in the vicinity of the Boomsnub/Airco site to connect to the public water system.1 This recommendation was made to ensure a continuing safe water supply for people who had wells in or adjacent to the contaminant plume.1
WDOH completed a public health assessment of the site in 1995 and determined that the site was a public health hazard because of the threat it posed to the municipal water supply wells which draw water from the Upper Troutdale aquifer.1 WDOH also determined that the Boomsnub facility, prior to its closure in 1994, represented a health hazard to site workers due to their exposure to chromium.1 As a result of its findings, WDOH made a number of recommendations: reduce or prevent exposure to contaminants; identify sources of contamination; and educate the public about the health implications of the site.1
The groundwater treatment system has continued to operate since EPA took over the site in 1994. The system has been expanded and EPA shares responsibility for the operation and maintenance of the system with BOC Gases.
On March 11, 1999, WDOH staff visited the Boomsnub/Airco site.3 EPA conducted a site tour of the Boomsnub property and pointed out various features on the BOC Gases property from the western-most fence line. Both the Boomsnub and BOC Gases properties are fenced. EPA controls access to the Boomsnub property; BOC Gases controls access to its property.
Surface soils were exposed in some areas of the Boomsnub property; other areas were paved or covered by structures. Some adjoining properties that were affected by Boomsnub's operation or by remediation activities conducted by EPA also had exposed surface soils. Much of the BOC Gases property appears to be paved or gravel covered.
A groundwater treatment system consisting of an ion exchange unit and an air stripping tower is located at the Boomsnub property. The system, operated by EPA and BOC Gases, was designed to remove chromium and volatile organic compounds from a groundwater contaminant plume located in the uppermost aquifer. The plume extends approximately 4,400 feet west of the site. Approximately 100 gallons of groundwater were being treated per minute. The treated groundwater is discharged to the City of Vancouver's sewer system.
In the course of their remedial investigation, EPA determined that the groundwater contaminant plume in the uppermost aquifer had migrated beyond the range of the groundwater extraction system. During the site visit, EPA was completing the installation of two additional extraction wells and three additional monitoring wells east of NE 30th Avenue to contain and monitor the plume. Contaminated groundwater collected near the toe of the plume, east of NE 30th Avenue, was being hauled by tanker truck to the Boomsnub property for treatment.
2.3. Environmental Investigations
When EPA took over the Boomsnub/Airco Superfund site in 1994, the site was divided into three operable units: Boomsnub Soil Operable Unit, BOC Gases Soil Operable Unit, and Site-Wide Groundwater Operable Unit (Figure 1). Environmental investigations were conducted at each of these areas in subsequent years.
Based on the 1990 census, Hazel Dell has a population of approximately 15,000 residents.1 Vancouver, which is adjacent to and south of Hazel Dell, has a population of approximately 135,000 residents.4 Approximately 95 percent of the area population are white; Asians or Pacific Islanders account for 2.3 percent of the population and 2.2 percent of the population are of Hispanic origin (persons of Hispanic origin may be of any race).1
The Boomsnub and BOC Gases properties are located in a predominantly mixed commercial and light industrial area. However, some private residences are located in the vicinity of the site. The contaminated groundwater plumes are located in an area that is mixed commercial, light industrial, residential, and agricultural.2
The City of Vancouver and the Clark Public Utilities own and operate water supply wells west of the site. There are also several private wells in the area.
The primary source of public and private potable water for the Vancouver and Hazel Dell area is the Upper Troutdale aquifer which is located approximately 150 feet below ground surface.1, 2, 5 Groundwater in the Upper Troutdale aquifer appears to flow to the southwest (Figure 1). Much of Hazel Dell and other unincorporated areas north of the City of Vancouver are serviced by Clark Public Utilities, whose nearest well is located approximately 1 mile west of the Boomsnub and BOC Gases properties in the Upper Troutdale aquifer.2 Clark Public Utilities currently services 22,000 homes.4 The City of Vancouver also has a water supply well approximately 1 mile west of the Boomsnub and BOC Gases properties in the Upper Troutdale aquifer. The City of Vancouver well services approximately 135,000 residents in Vancouver.4
The Upper Troutdale aquifer underlies an alluvial aquifer which is also a source of potable water for private wells near the site.2, 5 The Alluvial aquifer is relatively shallow, unconfined, and separated from the Upper Troutdale aquifer by a silty, clay aquitard of varying thickness. Groundwater in the Alluvial aquifer flows west/northwest from the Boomsnub and BOC Gases properties.2
2.7. Quality Assurance and Quality Control
In preparing the Public Health Assessment, the Washington State Department of Health relies on the information provided in the referenced documents and assumes that adequate quality assurance and quality control measures were followed with regard to sampling procedures, chain-of-custody, laboratory procedures, and data reporting. The validity of the analyses and the conclusions drawn for this Public Health Assessment are determined by the availability and reliability of the referenced information.
The public health effects associated with a site depend on two factors: the contaminants of concern and how people come into contact with the contaminant (i.e., exposure pathways).
Contaminants of concern are those chemicals found at a site that may cause health effects. However, not all chemicals found at a site are chemicals of concern and not all chemicals of concern are a health hazard.
In order for an exposure to a contaminant of concern to occur, all the elements of an exposure pathway must be in place. Exposure pathways are divided into completed and potential pathways and can be current, past, or future exposures. A completed exposure pathway consists of five elements: a contaminant source; environmental media that transport contaminants from the source (e.g., soil, groundwater, air); a point where people contact contaminated media (e.g., tap water); route of exposure by which a contaminant enters the human body (e.g., inhalation, ingestion, dermal contact or absorption); and a receptor population that is exposed to contaminants. A potential exposure pathway exists when some, but not all, of the five elements are present and the potential exists that the missing element(s) have been present, are present, or will be present in the future.
The completed and potential exposure pathways for each operable unit at the Boomsnub/Airco Superfund site are described below and summarized in Tables 1 and 2, respectively. The contaminants of concern for the completed exposure pathways are presented in Table 3. Appendix A summarizes how chemicals of concern were selected. Appendix B provides exposure assumptions that were used to calculate exposure doses. Appendix C describes how non-cancer adverse health effects and cancer risks are evaluated for each chemical of concern.
3.2. Boomsnub Soil Operable Unit
The Boomsnub Soil Operable Unit consists of the Boomsnub property where the chromium releases occurred; adjacent properties that were affected by releases from Boomsnub's operations (northern portion of the LaValley property adjacent to the Boomsnub property); or by releases that occurred during EPA's soil removal activities at the Boomsnub site in 1994 (Voorhies and eastern portion of the Heuvel properties and the railroad right-of-way) (Figure 2). The properties within the operable unit are either light industrial or commercial facilities and contain elevated levels of organic and inorganic contaminants.
The present receptor population includes commercial and industrial workers at the LaValley, Voorhies, Heuvel, and railroad right-of-way properties who may have contact with soils and can be exposed to contaminants through incidental ingestion, dermal contact, or through inhalation of fugitive dust. Remedial workers at the Boomsnub property were not considered a receptor population for this public health assessment because site activities at the Boomsnub property are conducted under a site-specific health and safety plan which is designed to reduce or prevent remedial worker exposure to contaminants. Although some scattered residences are located within the vicinity of the operable unit, they are unlikely to be exposed to the contaminants because the properties within the operable unit are fenced or access is otherwise limited. It is anticipated that future exposure to contaminants will also be limited to commercial and industrial site workers since the operable unit is surrounded by light industrial/commercial businesses.
3.2.1. Completed Exposure Pathways
A completed exposure pathway exists for workers exposed to surface soils via incidental ingestion, dermal contact, or inhalation of fugitive dust at the Voorhies property, the eastern portion of the Heuvel property, northern portion of the LaValley properties, and the railroad right-of-way located within the Boomsnub Soil Operable Unit (Table 1). It was conservatively assumed that workers were exposed to the contaminants of concern 5 days a week for 30 years. The cancer and non-cancer health effects associated with each contaminant of concern are summarized below.
Chromium
Chromium is present in the environment in several different forms: Chromium(0), chromium(III), and chromium(VI). Chromium(III) occurs naturally in the environment. Chromium (0) and chromium (VI) are generally produced by industrial processes. Because it can occur naturally in the environment, low levels of chromium are generally present in the soil. The natural background concentration of chromium in Clark County is approximately 27 mg/kg.6
Elevated total chromium concentrations were detected in surface soils (0-6 inches) along the northern portion of the LaValley property, the Voorhies property and the eastern portion of the Heuvel property, and the railroad right-of-way.2 Chromium was also detected at the Boomsnub property but as stated above, the Boomsnub property is not being evaluated as part of the public health assessment because work at the property is being done under a health and safety plan which is designed to reduce or prevent remedial worker exposure to contaminants. Figure 4 provides the total chromium concentrations detected in surface soils at all the properties within the Boomsnub Soil Operable Unit.
The maximum concentration of chromium (VI) in surface soils was detected at the Voorhies property. Although neither total chromium nor chromium (VI) was detected in surface soils above human health comparison levels at the northern portion of the LaValley property, the Voorhies property, the eastern portion of the Heuvel property, and the railroad right-of-way (Figure 3), it was carried forward for further evaluation since it was a chemical of concern during the previous public health assessment.
Chromium is an inhalation human carcinogen but is not a carcinogen by the ingestion and dermal exposure routes. However, it can cause non-cancer health effects through the ingestion, inhalation, and dermal exposure routes.
Non-cancer health effects are not anticipated for workers through incidental ingestion or dermal contact with the maximum total chromium and chromium (VI) levels detected at the northern portion of the LaValley property, the Voorhies property, the eastern portion of the Heuvel property, and the railroad right-of-way. Chromium (VI), an inhalation carcinogen and non-carcinogen above soil concentrations of 230 mg/kg, was detected in surface soil samples at those properties but at concentrations below 230 mg/kg.7 Therefore, no adverse health effects or significant cancer risk are expected through inhalation of chromium contaminated fugitive dust.
Arsenic
Arsenic was detected by EPA above soil screening values in only one surface sample along the eastern portion of the railroad right-of-way (32.3 mg/kg) near the Voorhies property. Like chromium, arsenic is also a naturally occurring element. Because it occurs naturally in the environment, low levels of arsenic are generally present in soil. The natural background concentration for arsenic in Clark County is approximately 6 mg/kg.6
Arsenic is normally taken into the body in small amounts through inhalation and ingestion of drinking water and food. Of these, food is the largest source of arsenic.8 If arsenic contaminated dust is inhaled, the dust particles settle onto the lining of the lungs.8 For dermal exposure, only a relatively small amount will go through the skin into the body, so this is not usually a concern.8
Non-cancer health effects for workers are not anticipated to result from incidental ingestion or dermal contact with arsenic at the maximum concentration detected at the railroad right-of-way (32.3 mg/kg). An increased cancer risk through incidental ingestion and dermal contact, however, could result from continual exposure to arsenic at this concentration. The maximum concentration, however, probably represents a "hot spot" and exposure to arsenic at this concentration would probably occur infrequently. WDOH, therefore, considers the cancer risk from exposure to arsenic along the railroad right-of-way insignificant.
The site is located in an area that receives significant rainfall throughout the year. Exposure to arsenic-contaminated dust would therefore be limited to the driest summer months. Neither cancer nor non-cancer health effects are anticipated to result from exposure to arsenic-contaminated fugitive dust during this limited exposure period.
Beryllium
Beryllium was detected from 0.52 to 0.81 mg/kg in a number of surface samples along the northern portion of the LaValley property, the Voorhies property, the eastern portion of the Heuvel property, and the railroad right-of-way.2 The highest concentration was detected at 0.81 mg/kg at the Voorhies property.
Beryllium is also a naturally occurring element. Because it occurs naturally in the environment, low levels of beryllium are generally present in the soil. The natural background concentration for beryllium in Clark County is 2 mg/kg, approximately two and one half times greater than the maximum concentration detected at the four properties.6 Beryllium occurs as an impurity in coal and fuel oil and is emitted into the air through chimneys.9
Beryllium can enter the body through inhalation of dust particles suspended in the air or by eating food or drinking water which contains it.9 If it is swallowed, it leaves the body in a few days.9 However, if it is inhaled, it may take months or years before the body rids itself of the beryllium.9 Beryllium can be harmful when you breathe it. The effects depend on how much and how long a person is exposed to it. Beryllium does not enter the body from skin contact unless the skin is scraped or cut and beryllium particles become embedded in the wound.9
Non-cancer health effects are not anticipated for workers who may be exposed to beryllium at the maximum concentration (0.81 mg/kg) through incidental ingestion or dermal contact. This is consistent with findings from studies done on humans and animals exposed to beryllium. The estimated risk to site workers exposed to beryllium at the maximum concentration would not result in a cancer risk that the WDOH considers significant. This is also consistent with studies on beryllium exposure.
The four properties are located in an area that receives significant rainfall throughout the year. Exposure to beryllium-contaminated dust would therefore be limited to the driest summer months. Neither cancer nor non-cancer health effects are anticipated to result from exposure to beryllium-contaminated fugitive dust at the maximum concentration (0.81 mg/kg) during this limited exposure period.
Carcinogenic Polynuclear Aromatic Hydrocarbons (CPAHs)
Carcinogenic polynuclear aromatic hydrocarbons (CPAHs) were detected in surface soil at the Voorhies property, and the railroad right-of-way. CPAHs were also detected behind the buildings at the LaValley property, just south of the Boomsnub property. The highest CPAH concentrations (9.7 mg/kg) occurred along the east side of the railroad right-of-way.
CPAHs are products of incomplete burning of fossil fuels, wood, garbage, fuels, and other organic substances and are ubiquitous in the environment. CPAHs can enter the body if skin comes into contact with soil that contains CPAHs.10 However, they do not tend to be stored in the body for a long time.10 CPAHs that enter the body are excreted within a few days.10 CPAHs can also enter the body through the lungs when a person breathes air that contains CPAH-contaminated dust or through incidental ingestion of CPAH contaminated soil.10
Benzo(a) pyrene, a CPAH with the highest potential risk, was selected as a conservative surrogate comparison value for evaluating CPAHs. Based on this very conservative comparison value, it was determined that four additional cancers would occur in a population of 10,000 site workers through incidental ingestion and dermal contact with the maximum CPAH concentration (9.7 mg/kg). The actual risk posed by the CPAHs at the properties, however, would be significantly lower than calculated because benzo(a) pyrene only makes up a small portion of the CPAHs detected and likely would not exceed a level WDOH considers significant.
The site is located in an area that receives significant rainfall throughout the year. Exposure to CPAH-contaminated dust would therefore be limited to the driest summer months. Neither cancer nor non-cancer health effects are anticipated to result from exposure to CPAH-contaminated fugitive dust at the maximum concentration (9.7 mg/kg) during this limited exposure period.
Chlordane
Chlordane was detected at 0.071 mg/kg in one surface soil sample along the eastside of the railroad right-of-way, adjacent to the Voorhies property. Chlordane is a man-made chemical that was used as a pesticide in the U.S. from 1948 to 1988. In soil, it attaches strongly to soil particles in the upper layers of soil and is unlikely to enter groundwater. It can remain in soil for over 20 years.11 Chlordane is sufficiently persistent that it may travel long distances and be deposited on land or in water far from its source.11
The most common chlordane exposure occurs from ingesting contaminated food.11 However, chlordane can enter the body through dermal contact with contaminated soil.11 Non-cancer health effects for workers are not anticipated to result from incidental ingestion or dermal contact with chlordane at the maximum concentration detected at the railroad right-of-way (0.071 mg/kg). An increased cancer risk through incidental ingestion and dermal contact could result from continual exposure to chlordane at this concentration. However, because this is a railroad right-of-way and only one sample had significant chlordane concentrations, workers are unlikely to be exposed to these concentrations on a continual basis. Therefore, the cancer risk associated with the maximum concentration is not anticipated to exceed a level WDOH considers significant.
No apparent public health hazard exists for workers exposed to the contaminants of concern in surface soil along the northern portion of the LaValley property, the Voorhies property, the eastern portion of the Heuvel property, or the railroad right-of-way at the Boomsnub Soil Operable Unit. It was conservatively assumed that workers were exposed to the contaminants of concern 5 days a week for 30 years. Actual exposure is probably significantly less since activities associated with the properties within the Operable Unit would result in less frequent contact with surface soils.
To reduce the chance of exposure, workers should continue to limit their exposure to surface soils along the northern portion of the LaValley property, the Voorhies property, the eastern portion of the Heuvel property, and the railroad right-of-way at the Boomsnub Soil Operable Unit.
3.2.4. Potential Exposure Pathways
Metals and organic compounds have been detected above soil screening levels in subsurface soils along the northern portion of the LaValley property, the Voorhies property, the eastern portion of the Heuvel property, and the railroad right-of-way at the Boomsnub Soil Operable Unit (Table 3). They have also been detected in subsurface soils at the Boomsnub property. Volatile organic compounds that appear to be related to releases at the BOC Gases property have been detected in soil gas above air screening values at the operable unit.
It is anticipated that future site use at the Boomsnub Soil Operable Unit will remain commercial or light industrial. The subsurface contamination, therefore, may pose a threat to workers through ingestion, dermal contact, and inhalation if activities at the properties involve contact with contaminated subsurface soils.
Contact with subsurface soils at the Boomsnub Soil Operable Unit may result in health effects if significantly high concentrations of soil contaminants are encountered during activities at the properties. Soil gas may also pose a threat to human health if it is encountered through exposure to subsurface soils.
Contact with subsurface soils should be minimized to prevent potential health effects. The WDOH should be notified by property owners, tenants, or public agencies that may be involved in the development of the properties about significant changes at the properties that may result in worker exposure to contaminated subsurface soils or soil gas. If site conditions change, WDOH can evaluate whether human health effects may occur.
3.3. BOC Gases Soil Operable Unit
The BOC Gases Soil Operable Unit consists of the BOC Gases property, an industrial facility located east of the Boomsnub Soil Operable Unit. Based on environmental investigations conducted at the BOC Gases property, it was determined that the property was the source of volatile organic compounds detected in groundwater since the mid-1990s.2, 12, 13, 14 Past and current exposure to contaminated soils at the property are limited to workers. It is anticipated that future exposure to contaminants at the Operable Unit will also be limited to workers since the property is located in a predominantly light industrial/commercial business area.
Limited data collected from the property indicates that the only chemical of concern detected in surface soils was trichloroethylene (TCE) which was detected at a maximum concentration of 250 mg/kg in sediments at a small dry well located in the western portion of the BOC Gases property. Most of the sediment in the dry well was subsequently removed in 1994. Sediments remaining in the dry well were retested for TCE after the removal was completed. The residual TCE concentration after removal was 6.9 mg/kg in the dry well which is below the 60 mg/kg human health comparison value for TCE.15
BOC Gases also collected and analyzed subsurface soils and soil gas for volatile organic compounds during its environmental investigations in an attempt to identify sources of the volatile organic contaminants at the site.2, 16 Subsurface soils and soil gas contained elevated levels of volatile organic compounds.
3.3.1. Complete Exposure Pathways
No completed exposure pathways exist at the BOC Gases Soil Operable Unit. Workers at the BOC Gases property are exposed to surface soils. However, there are no contaminants of concern in surface soils. Much of the BOC Gases property is paved or covered with structures. This prevents or greatly reduces volatile organic compounds in soil gas from discharging into the air.
3.3.2. Potential Exposure Pathways
As described above, volatile organic compounds have been detected in subsurface soils and soil gas at the BOC Gases Soil Operable Unit.
It is anticipated that future property use at the BOC Gases Soil Operable Unit will remain commercial or light industrial. The subsurface contamination, therefore, may pose a threat to workers through ingestion, dermal contact, and inhalation if site activities involve contact with the contaminated subsurface soil or exposure occurs to workers through contact with soil gas in subsurface soils.
Contact with subsurface soils at the BOC Gases Soil Operable Unit may result in health effects if significantly high concentrations of soil contaminants are encountered during site activities. Soil gas may also pose a threat to human health if it is encountered through exposure to subsurface soils.
Contact with subsurface soils should be minimized to prevent potential health effects. The WDOH should be notified by property owners or tenants or public agencies that may be involved in the cleanup or the development of the property about significant changes at the property that may result in exposure to contaminated subsurface soils or soil gas so it can evaluate whether human health effects may occur.
3.4. Site-Wide Groundwater Operating Unit
A number of groundwater investigations have been conducted at the site by Ecology, EPA, and BOC Gases since the late 1980s. The information collected from these investigations was used by EPA to determine the nature and extent of a commingled plume of groundwater contamination in the Alluvial aquifer (Figure 1). The information was also used to determine whether contamination had migrated into the underlying Upper Troutdale aquifer (Figure 1).
The contaminated groundwater identified in the Alluvial and Upper Troutdale aquifers during the investigation makes up the Site-Wide Groundwater Operable Unit. The Site-Wide Groundwater Operable Unit covers a significant area to the west of the Boomsnub and BOC Gases Soil Operable Units and consists of groundwater contaminated with metals (primarily chromium) and volatile organic compounds.
Alluvial Aquifer
A commingled plume of metals (primarily chromium) and volatile organic contaminated groundwater is located in the Alluvial aquifer. It was determined from the remedial investigation that the Alluvial aquifer plume is approximately 4,400 feet in length and approximately 900 feet wide.2 The contamination in the Alluvial aquifer originates at the Boomsnub/Airco site and moves west/northwest toward NE 30th Avenue.2 Based on analytical results from new monitoring and extraction wells, EPA has determined that the plume extends to just east of 30th Avenue NE (Figure 1).
The concentrations of a number of metals and volatile organic compounds in the Alluvial aquifer exceed groundwater screening levels.2 However, according to existing records, there are currently no known public or private wells drawing water from this contaminant plume.2, 5, 17 One private water supply well is located in the plume but the well was decommissioned in 1993 before the metals and volatile organic groundwater contaminants reached the well.5, 18 There are other private wells located adjacent to the Alluvial aquifer contaminant plume. Clark Public Utilities' records indicate that some of the residents with water supply wells near the contaminant plume in the Alluvial aquifer have connected to the public water system.5
Upper Troutdale Aquifer
Metals (primarily chromium) and volatile organic contaminated groundwater have been detected in the Upper Troutdale aquifer. The Upper Troutdale aquifer contamination is located near the eastern end of the Boomsnub/Airco site and extends toward the southwest. The areal extent of the contaminated groundwater in the Upper Troutdale aquifer is unknown (Figure 1). The contaminants of concern consist of low levels of arsenic, lead, chromium, and volatile organic compounds. The contaminant concentrations detected in the Upper Troutdale aquifer are, however, significantly less than found in the Alluvial aquifer.
There are a few private water supply wells located in the contaminated portion of the Upper Troutdale aquifer but the residences are hooked up to the public water supply system.5 There are also other private water supply wells within the area of groundwater contamination in the Alluvial and Upper Troutdale aquifers but they are used for industrial cooling water, irrigation water, or not at all.2, 19 One residence with a private water supply well immediately downgradient of the contaminated area may be using the water for household purposes (drinking water, cooking, and bathing); another Upper Troutdale well located approximately 1,500 feet downgradient of the contaminated area may also be used for household purposes.5
The City of Vancouver and Clark Public Utilities own and operate municipal drinking water supply wells that are located in the Upper Troutdale aquifer. It is unknown whether these wells could potentially be affected by the contamination in the Upper Troutdale aquifer because limited groundwater flow data is available for the Upper Troutdale aquifer.2
3.4.1. Completed Exposure Pathways
Currently, no known water supply wells located in the contaminated portion of the Alluvial and Upper Troutdale aquifers are withdrawing groundwater for potable water use. Therefore, no completed exposure pathways currently exist for the Site-Wide Groundwater Operable Unit.
3.4.2. Potential Exposure Pathways
As described above, the Alluvial and Upper Troutdale Aquifers contain metals (primarily chromium) and volatile organic contaminants of concern above human health comparison values. The contaminated groundwater poses a threat to human health through ingestion, dermal contact, and inhalation if groundwater is used as a potable water supply.
Use of the contaminated groundwater from the Alluvial or Upper Troutdale aquifers could result in exposure to metals and volatile organic compounds at levels of concern.
The Boomsnub/Airco site is categorized as a public health hazard because of the threat posed by the contaminated groundwater in the Alluvial and Upper Troutdale aquifers to municipal and private water supplies. Any new or existing water supply well installed in or adjacent to the area of contaminated groundwater in the aquifers could result in exposure to metals (primarily chromium) and volatile organic compounds via ingestion, inhalation, or dermal contact if the groundwater is not remediated.
EPA should expand its efforts to define and contain the groundwater contamination in the Alluvial and Upper Troutdale aquifers and remove or control the sources of contamination.
Municipal wells threatened by the groundwater contamination should continue to be closely monitored for metals and volatile organic compounds.
A door-to-door survey should be conducted to identify all existing and abandoned wells in or close to the identified path of the contaminated groundwater in the Alluvial and Upper Troutdale aquifers. People with private wells should be encouraged to connect to the municipal water supply. Appropriate steps should be taken to eliminate existing or abandoned wells if they are acting as conduits for contaminant transport.
Private and small public water supply wells located within and near the perimeter of the contaminated groundwater in the Alluvial and Upper Troutdale aquifers that are used for domestic or business purposes should be closely monitored for metals and volatile organic compounds. The WDOH should be notified about any anticipated changes in groundwater use by property owners or tenants or agencies involved in overseeing groundwater use in the area so the WDOH can evaluate whether human health effects will result from exposure to groundwater contaminants.
The potential for exposure and subsequent adverse health effects are often increased for young children when compared with older children or adults. For example, children drink more water per body weight than do adults and, therefore, receive higher exposures than adults. In addition to the potential for higher exposures of young children, the risk of adverse health effects is also increased. ATSDR and WDOH recognize that children are susceptible to developmental toxicity that can occur at levels much lower than those causing other types of toxicity.
Neither current nor past exposure to contaminants has occurred to young children at the site. Future exposures, however, could occur if, for example, land use changes to residential or groundwater within the contaminated areas is used as a potable water supply. WDOH should be contacted by property owners or tenants or agencies so it can evaluate potential health effects associated with such proposed changes.
The Washington Department of Health (WDOH) participated in the April 22, 1999, Clark County Hazardous Waste Task Force meeting in Vancouver, Washington, in order to present information to the community about the purpose of the current Public Health Assessment and to gather community health concerns about the site. A questionnaire was also made available at the meeting to provide the community with an additional opportunity to submit health concerns to WDOH.
The following health-related questions were posed by the public:
A resident expressed concern about the quality of the drinking water at the First Church of God school because her child is a student at the school. The First Church of God is located above the contaminant plume in the Alluvial aquifer.
The First Church of God obtains its water from the Clark Public Utilities. The Clark Public Utilities' wells are located outside the area of groundwater contamination. The wells are closely monitored by Clark Public Utilities to ensure a safe public water supply.
A person that worked at the Boomsnub property for less than 1 month during some of EPA's remedial activities wanted to know if his exposure to the contaminants could affect his health.
Workers involved in remedial activities at hazardous waste sites are required to conduct their work in compliance with a site-specific health and safety plan. The health and safety plan describes the contaminants found at a site and how workers need to protect themselves from exposure to contaminants. Workers who follow the health and safety plan are unlikely to be exposed to harmful levels of contaminants.
The Public Health Action Plan for the Boomsnub/Airco Superfund site is summarized below. The purpose of the Public Health Action Plan is to ensure that this public health assessment not only identifies public health hazards, but provides a plan of action designed to prevent or mitigate adverse human health effects resulting from exposure to hazardous substances in the environment.
Actions Taken:
Actions Proposed:
Barbara J. Trejo
Public Health Advisor
Washington State Department of Health
Office of Environmental Health Assessments
WA DOH Designated Reviewer
Rob Duff
Program Manager
Washington State Department of Health
Office of Environmental Health Assessments
ATSDR Designated Reviewer
Debra Gable
Technical Project Officer
State Program Section
Agency for Toxic Substances and Disease Registry
Table 1. Completed Exposure Pathways for the Boomsnub/Airco Superfund Site
| Pathway Name | Source | Environmental Media | Point of Exposure | Route of Exposure | Exposed Population | Time |
| Boomsnub Soil Operable Unit | Boomsnub | Surface Soil | Boomsnub and adjacent properties | Inhalation Dermal Ingestion |
Workers | Past Present |
Table 2: Potential Exposure Pathways for the Boomsnub/Airco
Superfund Site
| Pathway Name | Source | Environmental Media | Point of Exposure | Route of Exposure | Exposed Population | Time |
| Boomsnub Soil Operable Unit | Boomsnub | Surface and Subsurface Soil Soil Gas |
None None |
Inhalation Dermal Ingestion Inhalation |
Worker Worker |
Future Future |
| BOC Gases Soil Operable Unit | BOC Gases | Subsurface Soil Soil Gas |
None None |
Inhalation Dermal Ingestion Inhalation |
Worker Worker |
Future Future |
| Site-Wide Groundwater Operable Unit - Alluvial Aquifer | Boomsnub BOC Gases | Groundwater | None | Inhalation Dermal Ingestion |
Residents with Private Wells | Future |
| Site-Wide Groundwater Operable Unit - Upper Troutdale Aquifer | Boomsnub BOC Gases | Groundwater | None | Inhalation Dermal Ingestion |
Vancouver and Hazel Dell Residents | Future |
Table 3: Boomsnub Soil Operable Unit - LaValley, Voorhies,
Railroad Right-of-Way and Heuvel Properties
Maximum Levels of Contaminants of Concern and Human Health Comparison Values
- Soil
| Contaminant | Soil Concentration | Background | Comparison Value | ||
| 0-6" | >6" | Concentration | Ingestion | ||
| mg/kg | mg/kg | mg/kg | mg/kg | Source | |
| Semi-volatile Organics | |||||
| Carcinogenic PAHs (CPAH) | 9.78 | 1.62 | NA | 0.1 | CREG a |
| Pesticides | |||||
| Total Chlordane | 0.71 | 0.0194 | NA | 0.5 | CREG |
| Metals | |||||
| Arsenic | 32.3J | 13.5J | 5.81 | 0.5 | CREG |
| Beryllium | 0.81 | 0.99 | 2.07 | 0.2 | CREG |
| Total Chromium | 1030 | 1010 | 27 | 2000 | RMEG b |
| Hexavalent Chromium | 26 | 40 | NA | 2000 | RMEG |
J = Reported value is an estimate
NA = not applicable
a) Benzo(a) pyrene used as a surrogate for CPAHs
b) Comparison value for Chromium (VI)
Figure 1. Boomsnub/BOC Gases Site Map Location
Figure 2. Site Plan - Boomsnub Soil Operable Unit
Figure 3. Monitoring and Extraction Well Network
Figure 4. Chromium Concentrations - Boomsnub Soil Operable Unit
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