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1. ATSDR > Public Health Assessments & Consultations

PUBLIC HEALTH ASSESSMENT

MUSKEGO SANITARY LANDFILL
MUSKEGO, WAUKESHA COUNTY, WISCONSIN

ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS

The sampling conducted on and around Muskego Sanitary Landfill has included various media. This sampling is summarized in Table 1.

A. On-site Contamination

There are a three areas at Muskego Sanitary Landfill which constitutes the Superfund site. They are: 1) The Old Fill area; 2) The Southeast Fill area; 3) The Non-contiguous Fill area (which includes the Drum Trench, the "L-shaped" area, and two elongated fill areas). The use of the term "On-Site" refers to locations found within one or more of these areas. The hazardous contaminants have been detected on-site in the refuse, leachate, basal soils, ambient air, and groundwater of these areas. Contaminant concentrations in leachate from the Old Fill and the Southeast fill areas are among the highest found on the site (Table 2). Most chemicals found in other media at levels of health concern in were also detected in leachate at higher levels.

One on-site well exhibited the highest concentrations of specific VOCs in any media found on the site. Groundwater from this well (E136), found within the "L-shaped" boundary of the Non-contiguous Fill area, had 12,000 µg/L of toluene, 7,300 µg/L of ethylbenzene, and 39,000 µg/L of xylenes.

Table 1: Summary of Media Sampling
Muskego Sanitary Landfill
Waukesha County, Wisconsin

Media	Date	Sampler	Location	Parameters
Leachate	1982 & 84 1988 & 90	Warzyn34 Warzyn39	a,b a,b	VOC, SVOC, PPCB, Metals, Indicators VOC, SVOC, PPCB, Metals, Indicators
Surface Water	1982	Warzyn34	e	VOC, SVOC, PPCB, Metals, Indicators
Sediment/Sludge	1982 1983 & 85 1986 1988 1990	DNR34 F&VD21,22 Zimpro42 F&VD23 Warzyn39	e e e e d	Indicators Indicators VOC VOC VOC, SVOC, PPCB, Metals
Ambient Air	1988	Warzyn39	d	VOC
Groundwater	1974 & 75 1982 1983 1984 1985, 86 & 87 1988 & 89 1990 1991 1991	EMCON20 Warzyn34 Warzyn34 Warzyn34 Warzyn34 Warzyn39 Warzyn39 Warzyn39 USEPA26	c,d a,b,d,f d,f a,b,d,f d,f d c,d c,d,f f	Indicators Indicators Indicators VOC, SVOC, PPCB, Metals, Indicators Metals, Indicators VOC, SVOC VOC, SVOC, PPCB, Metals, Indicators VOC, SVOC, PPCB, Metals, Indicators VOC

Air

Leachate head/gas vent air samples were collected on-site in 1988. See the discussion of off-site ambient contamination for the analytical results.

B. Off-site Contamination

Groundwater

Groundwater in the general vicinity of the site was described in the Site Evaluation Report as "adequate to meet most domestic, municipal and industrial water needs" [34, p22]. However this report also described water quality as "poor", which was based on the 1982-84 sampling from on-site wells, monitoring wells, and adjacent private wells to the site [34, p36].

Table 2: Chemicals in Leachate
Muskego Sanitary Landfill
Waukesha County, Wisconsin

Thirteen off-site groundwater monitoring wells were installed in 1984 at locations around the site in order to supplement available water quality data [34, p9]. In 1982 and 1984 water samples were collected from monitoring wells and private wells around the site. Samples were analyzed for pH, conductivity, total organic carbon, hardness, alkalinity, and certain inorganic compounds [34, Appendix G]. The results from three private wells (PW-4, PW-5, & PW-6) exhibited signs of decreased water quality. Two of these private wells (PW-5 & PW-6) had elevated lead concentrations (300 µg/L and 100 µg/L), chlorides and conductivity [34, p36]. These two residences now use alternate water supplies, however information is not available about when the wells were abandoned nor who was exposed to contaminated water drawn from these wells.

The two rounds of 1984 private well testing also showed a fourth private well (PW-1) to have a measurable contamination of one VOC (total 1,2-dichloroethylene detected at 14 & 16 µg/L), with trace levels of other VOCs (tetrachloroethylene, and toluene) [34, Appendix G]. This well (PW-1) was abandoned on June 25, 1990 [36, p3-17].

* Exceeds comparison value
a Cancer Risk Evaluation Guide for 10^-6 excess cancer risk
b EPA's Maximum Contaminant Level

Source: Warzyn, Inc. Remedial Investigation/Feasibility Study - Muskego Sanitary Landfill Site, Technical Memorandum No. 1, Report 13527. Madison, Wisconsin: Warzyn, April 1989, Table 24, Groundwater Monitoring Wells Only.

The first stage of the Remedial Investigation was conducted, in part, to identify and characterize the contaminant migration routes [35, p1-2]. Groundwater samples were collected from off-site monitoring wells, which are below the zone of saturation, filtered, and preserved. Samples were analyzed for pH, conductivity, and target VOCs [35, p2-10]. These results are presented in Table 3 and demonstrate the presence of VOCs in groundwater. Three of these compounds (benzene, tetrachloroethylene, and trichloroethylene) were detected at levels which exceed the Wisconsin Public Health Groundwater Enforcement Standards [40]. Results of the analyses were considered estimated because of a reduced level of quality control was employed during the sampling and analyses [35, p3-22].

In June 1990 testing of off-site groundwater was conducted to further determine the extent of groundwater contamination along potential migration pathways. Water samples were collected from 23 off-site groundwater monitoring wells adjacent to the Old Fill, Southeastern Fill, and Non-contiguous Fill areas [36, p2-11]. This sampling did not include private wells. Samples were collected from points along potential migration routes [36, p2-11]. Analyses were conducted for VOCs, SVOCs, pesticides, and inorganic chemicals. In January 1991 groundwater samples were collected from 24 off-site monitoring wells (the 23 previously sampled and one additional well).

Table 4: Chemicals of Potential Health Concern in
Off-site Groundwater Monitoring Wells
Muskego Sanitary Landfill
Waukesha County, Wisconsin

* Exceeds comparison value
a Cancer Risk Evaluation Guide for 10^-6 excess cancer risk
b EPA's Drinking Water Lifetime Health Advisory
c Cancer Slope Factor [29]
d EPA's Action Level
e ATSDR's Environmental Media Evaluation Guide
f EPA's Reference Dose

Sources: Warzyn, Inc. Remedial Investigation/Feasibility Study - Muskego Sanitary Landfill Site, Technical Memorandum No. 2, Report 13527. Madison, Wisconsin: Warzyn, January 1991, Appendix J-2 (Groundwater Analytical Results).

Warzyn, Inc. Remedial Investigation/Feasibility Study - Muskego Sanitary Landfill Site, Supplement to Technical Memorandum No. 2, Report 13527. Madison, Wisconsin: June 1991, Appendix B-2.

The results for the 1990 and 1991 groundwater testing detected VOCs, SVOCs, and heavy metals (Table 4). Pesticides and polychlorinated biphenyls were not detected in these results. Contaminants which exceed the Wisconsin Public Health Groundwater Quality Enforcement Standard [40] included benzene, 1,2-dichloroethane, tetrachloroethylene, trichloroethylene, vinyl chloride.

In 1991 private wells adjacent to the site were tested for VOCs three times and no contaminants were detected. Samples were collected in January, May, and August of 1991, by U.S. EPA and WMWI [26, 37, 39]. Two of the wells sampled provide the sole source of water on the property. Four other wells are at locations which are connected to the municipal water system. It is reported that well water at these four locations is not used for drinking, cooking, or bathing. These six wells are apparently in the path of contaminated groundwater. In December 1991 the DNR recommended to the U.S. EPA that groundwater and private well monitoring continue on a cycle of at least twice per year [19].

Sediment

The first round of surface sediment samples were collected in June 1990. Samples were taken at three locations (SD1 to SD3) in drainages east of the Old Fill and Southeast Fill areas (Figure 3). At each location samples were collected from the top one inch of the surface sediment over a one square foot area. Samples were collected with stainless steel spoons and placed in stainless steel bowls from which they were deposited in the sample jars. All samples were analyzed for VOCs, SVOCs, pesticides, and inorganic chemicals. Information was not available concerning field or laboratory blanks collected [36, p2-13].

In 1991 a second round of sediment sampling was conducted because contaminants were found in sediments near the site boundary during the first round [36, p4-16]. Samples were collected from five new locations around the site (SD4 to SD8). Refer to Figure 3 for the location of sampling points. Two sampling locations (SD4 & SD6) were in the eastern wetland. Sample SD8 was intended to be a background sample and was collected from a drainage ditch west of the site and across Crowbar Road [37, p4-16].

The results of sediment sampling found a low level of 1,1-dichloroethane (11 µg/kg) at SD4 and low levels of toluene at SD1, SD3, SD4, and SD8 (190 µg/kg highest level detected). There were trace levels of other VOCs and SVOCs detected in these samples. There were no detections of contaminants in the sample from SD2. Though the results show relatively low levels of these contaminants, Warzyn, the Remedial Investigation/Feasibility Study (RI/FS) contractor, did note that these levels "may represent the potential for off-site migration" of contaminants [36, p3-25]. In round two there were no contaminants detected in samples collected from SD5, SD6, and SD7. Heavy metals, PCBs (polychlorinated biphenyls), and pesticides were not detected in these samples.

Ambient Air

Between October 30 & November 1, 1988, ambient air samples were collected at seven locations around the perimeter of the site [35, p2-20]. The placement of these monitoring stations was not reported. The samples were collected by drawing air through a charcoal resin at a controlled rate of flow over a 24-hour period. These samples were analyzed for VOCs and the results are shown in Table 5. Though testing of the samples were qualified because the analytical laboratory exceeded the specified sample holding times, there was a high frequency of detection for VOC compounds. No information was provided about wind direction, wind speed, temperature, or humidity during the sampling. The RI/FS did report that predominant winds at the site are from the west and the southwest (a 23% and 18% occurrence respectively) [36, Appendix I].

Table 5: Chemicals of Concern in Off-site Ambient Air
November 1988
Muskego Sanitary Landfill
Waukesha County, Wisconsin

* Exceeds comparison value
a Cancer Risk Evaluation Guide for 10^-6 excess cancer risk
b EPA's Maximum Contaminant Level

Source: Warzyn, Inc. Remedial Investigation/Feasibility Study - Muskego Sanitary Landfill Site, Technical Memorandum No. 1, Report 13527. Madison, Wisconsin: Warzyn, April 1989.

Many of the VOCs found in air around the site's perimeter also occur in gases in the on-site fill areas. The concentrations of the VOCs in landfill gases are much higher than their concentrations in air around the site. Vapor samples were collected from a leachate-head well and gas vent, and the results are shown in Table 6.

^a Concentration reported is total for all isomers.

Source: Warzyn, Inc. Remedial Investigation/Feasibility Study - Muskego Sanitary Landfill Site, Technical Memorandum No. 1, Report 13527. Madison, Wisconsin: Warzyn, April 1989, Table 15.

C. Toxic Chemical Release Inventory

A Toxic Chemical Release Inventory (TRI) search was conducted by DOH of Muskego and Big Bend zip codes for any previously reported toxic chemicals. The TRI is searched in order to investigate any other sources of environmental contamination near the site. Certain manufacturers are required to report to the U.S. EPA of releases to the environment of over 300 hazardous chemicals. This reported information is entered into the computerized TRI system. The TRI search did not list any reports of hazardous substance releases or transferrances for the Muskego or Big Bend zip codes.

D. Quality Assurance And Quality Control

The DOH assumes that WMWI and Warzyn Engineering (the RI/FS contractor) fully met the objectives described in the Quality Assurance Project Plan (dated 12/87). The ability of the DOH to make valid conclusions is dependent, to some extent, on the amount and quality of data provided. These quality assurance and quality control measures were to be followed during field sampling and measurements, the chain of custody activities, laboratory analytical procedures, and data reporting.

The results of the ambient air sampling were qualified in the RI/FS as "estimated" because the analyzing laboratory exceeded the recommended holding times for the samples. Despite this a number of VOCs were detected in the samples. Other than this exception the remedial investigation met the requirements for the Quality Assurance Project Plan, as approved by the U.S. EPA.

E. Physical And Other Hazards

Landfill Gas

Landfill gas was detected at Muskego Sanitary Landfill in 1984 and controls (extraction and venting system) were installed. Methane, a large constituent of landfill gas, is generated from the decomposition of organic material found in refuse deposited at the site. Landfill gas is a potential hazard because it can migrate away from the site, move into the basements of nearby buildings and homes, and accumulate up to explosive levels. A spark from a furnace, water heater, or a mechanical source could ignite the gas at such a level.

A landfill gas monitoring system (totalling 47 probes and vents) has been installed to monitor the situation. It was reported in 1988 by the RI/FS contractor that the migration of methane gas from the site appears to be controlled by the extraction and venting system [34, p39]. Therefore landfill gas Muskego Sanitary Landfill is not a hazard to nearby buildings and homes.

Other Hazards

DOH representatives did not observe any physical hazards when they visited the site.

Figure 3. Muskego Sanitary Landfill - Sediment Sampling Points

PATHWAYS ANALYSES

Some people living immediately east of Muskego Sanitary Landfill possibly were exposed to VOC contamination carried away from the site by ambient air. However questions about the sampling process and results make it difficult to draw conclusions about these potential human exposures. Three nearby private wells were shown to contain site-related contamination, but these wells are no longer in use. No other nearby private wells have been shown to be contaminated. If the site were not cleaned-up then contaminated groundwater in the vicinity of the site could migrate away and reach these private wells. DOH assumes that direct physical contact with contaminated refuse and leachate is unlikely to occur because each site is covered with fill and is capped. Furthermore there have been no reports of these materials being uncovered at the site. Physical contact with leachate might occur as a result of the extraction process, however its handling and removal is tightly controlled. Direct physical exposure with hazardous substances could result from contact with contaminated ambient air and/or groundwater.

A. Completed Exposure Pathways

Air

In 1988 four VOCs were detected in off-site air at levels of potential health concern. Because prevalent winds blow across the site and toward nearby homes, residents likely breathed VOCs in the air. The VOCs detected were benzene, methylene chloride, tetrachloroethylene, trichloroethylene.

The validity of the ambient air sampling results are questioned because the analyzing laboratory held the samples beyond the recommended holding times. Despite analyzed samples exceeding the holding times, VOCs were still detected. It is possible that samples initially contained higher concentrations of VOCs than the analyses revealed.

The lack of information about locations of the sampling sites and weather conditions during sampling makes it difficult to evaluate how much of the detected airborne contamination was from the site. Using general weather information about the site, predominant winds could carry airborne contaminants toward private residences on Hillendale Road. There are approximately 25 homes directly east of the site that could be affected by contaminants transported by ambient air.

Additional data is necessary to accurately assess the extent of past and present human exposures to ambient air contamination originating from the site. The ambient air sampling results were taken over a single 24-hour period and do not fully characterize the extent of airborne contamination around the site and at nearby homes. Dispersion would probably cause air contamination at nearby homes to be lower than the levels detected at the site perimeter. Sampling of ambient air during various atmospheric conditions at these homes would provide a clearer indication of VOC contamination that people might be experiencing. Such sampling would also help determine the extent of VOC contamination which is not site-related. Past exposures could then be estimated from present exposure.

If nearby residents are being breathing this site-related VOC contamination the possibility of continued exposure is dependent on how the site is cleaned-up. If the proposed U.S. EPA remediation is fully implemented there would likely be a significant reduction in ambient air contamination from the site. This remediation includes an in-situ vapor extraction system at the Non-Contiguous Fill area and active landfill gas control measures at the New and Old Fill areas. If these clean-up measures are not implemented then air could still carry VOCs away from the site and sampling should then be conducted to assess the extent of airborne contamination reaching nearby homes.

Groundwater

Some people were probably exposed in the past to chemicals in drinking water which may have originated from the site. These chemicals may have been carried away and downgradient from the site in groundwater, and were drawn by private wells.

Three nearby private wells were abandoned after showing contamination. People probably drank water contaminated with lead in two of these households (PW-5 & PW-6). People living in one household (PW-6) were probably exposed (ingestion, dermal contact and inhalation) to water contaminated with 1,2-dichloroethylene. No other private wells in the area are known to have been or currently are drawing contaminated water.

B. Potential Exposure Pathways

Groundwater

Present exposure to hazardous chemicals in groundwater is probably not occurring because all contaminated water supply wells around the site have been abandoned. However the potential remains for the water supplied by other private wells to become contaminated.

Hazardous chemicals detected in site leachate (VOCs, SVOCs and heavy metals) are the primary source of contaminants entering the groundwater. Most contaminants observed in off-site groundwater monitoring wells were also detected at higher levels in on-site leachate.

Groundwater in the vicinity of the site generally flows to the southeast in the sand and gravel aquifer, and can carry contamination away from the site [36, p4-1]. However the movement of contaminated groundwater in the shallow aquifer under the site is complicated by the impermeable layers of clay/till and sand/gravel (refer to Site Geology on page 5). These layers affect the way contamination leaves each fill area. Migration of contaminants away from the Old Fill area occurs as leachate enters the groundwater which flows northwest over the impermeable lacustrine clays and glacial tills. As the contaminated groundwater reaches the edge of the clay and glacial till, it flows down into the outwash sand/gravel aquifer and flows back to the south under the site. At some places within the Old Fill area where the impermeable clay/till material does not exist, contaminants migrate directly down into the outwash sand and gravel aquifer. The contaminants at the Non-Contiguous Fill area enter directly into the outwash sand and gravel aquifer as no impermeable layer is present. Contaminated groundwater movement away from the Southeast Fill area is impaired by natural clay soils under the site and the active leachate extraction process [36, p4-1].

Six private wells tested for VOCs in August 1991 showed no contamination [26]. The furthest extent of contamination from the site is 800 feet south (E-135) and 400 feet southeast (P-64) away. These 36 private wells may be affected if contaminated groundwater continues to move away from the site. WMWI plans to continue quarterly monitoring of selected nearby private wells.

Despite the availability of municipal water, private wells are still used in the immediate vicinity of the site. There are 35 private wells east, southeast, and south of the site which draw water from the outwash sand and gravel aquifer. Ten of these homes continue to obtain all drinking water from private wells. Fifteen of nearby homes are connected to municipal water and the owners have not abandoned their wells. The well water at these homes is reportedly used for agricultural and/or livestock purposes and is not drank by people or used for domestic purposes. DNR regulations prohibit new well drilling within 1,200 feet of a landfill as part of an "isolation distance", though it may be difficult to enforce this regulation [41]. Consequently, no new wells are likely to be drilled in the vicinity of the potentially affected wells.

An estimated 25 people could be exposed to hazardous chemicals if contaminated groundwater was to reach the ten households that still use private wells as their sole source of water (assuming 2.5 people per home). The chemicals detected in groundwater monitoring wells of potential health concern are VOCs (benzene, 1,2,-dichloroethane, 1,2-dichloropropane, tetrachloroethylene, trichloroethylene, and vinyl chloride). The people could be exposed by ingesting contaminated water, breathing from vapors released during the use of water, and/or contact the skin of people bathing or washing.

Sediment

There is no evidence that people have come in contact with contaminants carried away from the site in sediment, but a potential pathway exists for human exposure. Contaminated soils could be carried off-site in sediment media. The RI/FS contractor stated that "sediment is a potential migration pathway for contaminants" originating from the site which entered drainages during landfilling, leachate seeps, or during prior Anamax operations [37, p4-22]. Surface water runoff from the site apparently has carried sediment into one of two wetlands: one along the southern border and another in the southeast corner of the site. A WMWI representative stated during the October 1991 site visit that runoff tends to remain on property owned by either WMWI or the Anamax Rendering Company. However, some runoff originating from the site probably flows from the southeastern wetland, though a culvert under Janesville Road, and into a separate wetland on private property south of Janesville road. While contaminated sediment and/or surface water may travel south of Janesville Road, neither sediment nor surface water from this private wetland has been tested.

Contaminants were detected in sediment collected from the off-site wetland located southeast of the site and the drainways leading to the wetland. Low-levels of toluene and 1,1-dichloroethane, and trace levels of other VOCs and SVOCs were detected. Though the testing of wetland surface water for contaminants has not been conducted, it is unlikely that the low-level contaminants in sediment could migrate into surface water and have a substantial affect on water concentrations.

One household adjacent to the site reported using water from the southeastern wetland to irrigate their orchard during dry summer months [16]. Contaminated sediment could be taken up with surface water during pumping and watering of the fruit trees. These two VOCs could be released into the air during watering or taken up by fruit trees. A person watering the trees might breath these vapors. However these two VOCs were detected at such low levels that even if large amounts of sediment was drawn while watering the trees and all VOCs were released, the highest possible exposure would not be of a health concern. It is unlikely that the trees would absorb VOCs through the roots and it would affect the fruit.

Sediments at Muskego Sanitary Landfill represent a potential human exposure pathway because a pathway for exposure exists, however contaminants detected in sediment are not at a level of health concern.

PUBLIC HEALTH IMPLICATIONS

A. Toxicological Evaluation

The chemicals of concern at Muskego Sanitary Landfill site are summarized below, in Table 7.

Table 7: Chemicals of Concern
Muskego Sanitary Landfill
Waukesha County, Wisconsin

Benzene

Human exposure to benzene may have occurred through ambient air contamination, but is unlikely to have happened as the result of contaminated groundwater.

Ambient Air

Workers at the site and nearby residents may be breathing low-level benzene in the air. Ambient air testing at Muskego detected benzene at all seven sampling locations around the perimeter of the site. Concentrations ranged from 1.7 to 8.1 µg/m³. Though ambient air sampling has not been performed adjacent to private residences, airborne contamination has likely followed the prevalent wind direction, reaching homes to the east of the site. The range of benzene levels found in air at the site are slightly above [1, p110] the average typically found in suburban and urban areas (1.8 µg/m³).

A person inhaling the highest detected level of benzene (8.1 µg/m³) over a long period could suppress the immune system [1, p25]. The immune system is reported to be one of the most sensitive human organs to benzene toxicity [1, p13]. The U.S. EPA classifies benzene as a known human carcinogen [28]. People who breath air contaminated with benzene at 8.1 µg/m³ for a lifetime could face a low-increased risk of cancer. Benzene is known to cause leukemia in workers exposed over several years to low levels in air, and has been shown to cause several types of cancer in laboratory animals [28].

Groundwater

If contaminated groundwater reaches nearby private water supplies, people could be exposed to benzene in drinking water and indoor air. Benzene has not been detected in any private wells but has reached number of off-site monitoring wells on WMWI and Anamax property. The highest level of benzene detected was 21 µg/L in an off-site groundwater monitoring wells. Though benzene contaminated groundwater has been found only adjacent to the site, the possibility exists that this contamination may reach private wells.

People drinking water for a lifetime contaminated with a benzene level of 21 µg/L would face no apparent increased risk of cancer. Though inhaled benzene is classified as a known human carcinogen, there is little information available about the human cancer effects of ingesting benzene. The U.S. EPA determined that ingesting benzene causes cancer in people based on studies of people who inhaled benzene and on studies of laboratory animals that ingested benzene [1, p75]. Cancer studies in animals link benzene to leukemia in rodents and various organ carcinomas in rats [1, p45]. There are no other health effects expected from such levels of benzene in groundwater.

The normal household use (washing, bathing, etc.) of water contaminated with benzene at level of 21 µg/L would result in benzene vapors being released. A person inhaling these benzene-contaminated vapors for a lifetime would have a low increased risk of cancer. The relevant health effects from inhaling benzene are covered above under the ambient air discussion.

1,2-Dichloroethane

If groundwater contaminated with 1,2-dichloroethane (1,2-DCA) reaches nearby private water supplies, people could be exposed to 1,2-DCA in drinking water, indoor air and bath water. Human exposure to 1,2-dichloroethane probably has not occurred around the site, as it has not been detected in any nearby private wells.

Monitoring wells around the site show that groundwater has limited contamination from 1,2-DCA. This VOC was detected in 6 of 23 wells during the June 1990 off-site groundwater monitoring and in 3 of 24 wells during the January 1991 groundwater monitoring. The highest level of 1,2-DCA detected in monitoring wells was 9 µg/L, which exceeds the Wisconsin Public Health Groundwater Enforcement Standard of 5 µg/L [40].

People drinking water contaminated with these levels of 1,2-DCA face no apparent, measurable increased cancer risk. Ingesting 1,2-DCA is thought to increase cancer risk in people because oral exposures have been shown to cause cancer in laboratory animals. Studies of laboratory rats and mice exposed to 1,2-DCA have shown increased levels of specific tumors [3, p30]. There are no other health effects associated with the levels of 1,2-DCA found in groundwater around the site.

1,2-Dichloroethylene (1,2-DCE)

Human exposure to 1,2-dichloroethylene (total or both isomers) from a water supply probably happened at one private residence near the site. People were likely exposed to 1,2-dichloroethylene (1,2-DCE) in drinking water and indoor air. The number of individuals affected and length of 1,2-DCE exposure is not known. The home was torn down and the well was abandoned in 1990. The levels of 1,2-DCE detected are not of a health concern.

Contaminated well water was found at this residence (PW-1) during both rounds of the 1984 groundwater testing. These 1984 test results showed 1,2-DCE levels at 14 and 16 µg/L. There was no further testing of this well for contaminants. It is possible that 1,2-DCE contamination may have been higher before the water supply was tested. Therefore it is not feasible to plot levels of contamination or human exposure through time.

No other private wells around the site have shown contamination from 1,2-DCE. However the chemical was detected in eight monitoring wells during the June 1990 and January 1991 off-site groundwater testing. The 1,2-DCE levels in these monitoring wells was in the range of 1 to 12.5 µg/L.

The long-term health effects on humans and animals from ingesting low levels of 1,2-DCE are unknown. There have been no reports of adverse effects to health in humans or animals exposed to low concentrations of 1,2-DCE [4]. If 1,2-DCE were to reach other water supplies, no health effects are likely to occur because the concentrations are so low.

1,2-Dichloropropane

If groundwater contaminated with 1,2-dichloropropane reaches a nearby residence people could be exposed to the chemical in drinking water, indoor air, and bath water. People around the site have probably not been exposed to 1,2-dichloropropane as it has not been detected in any private wells. 1,2-Dichloropropane has been found in monitoring wells around the site and the contaminated groundwater is probably moving away from the site.

1,2-Dichloropropane was detected in 3 of 23 wells during the June 1990 off-site groundwater monitoring and in 3 of 24 wells during the January 1991 monitoring. The level detected ranged 2 to 5 µg/L for both rounds of monitoring.

People drinking groundwater contaminated with this level of 1,2-dichloropropane have no apparent, measurable increased cancer risk. 1,2-Dichloropropane has been categorized as a probable human carcinogen by the U.S. EPA. Though 1,2-dichloropropane is not known to cause cancer in people, studies of laboratory mice have shown 1,2-dichloropropane to cause liver tumors [29, p3-13]. There are no other health effects known for the levels of 1,2-dichloropropane detected at the site.

Methylene Chloride

Human exposure to methylene chloride may have occurred though ambient air contamination but is unlikely to have happened as the result of contaminated groundwater.

Ambient Air

Workers at the site and nearby residents may have breathed methylene chloride in the air. Ambient air testing at Muskego Sanitary Landfill detected methylene chloride. Air testing has not been conducted near private residences, though airborne contamination of methylene chloride has probably followed prevalent winds and reached homes to the east of the site.

Off-site ambient air testing at Muskego detected the presence of methylene chloride at all seven sampling locations located around the site perimeter. Ambient air methylene chloride concentrations covered the range from 3.6 to 50.4 µg/m³.

Levels of methylene chloride detected in ambient air around the site are higher than normal. Background levels of methylene chloride in rural and suburban settings [7, p63] are reported to be less than 2 µg/m³.

People breathing methylene chloride contaminated air around the site for a lifetime have a low increased risk of cancer. The U.S. EPA classifies methylene chloride as a probable human carcinogen. Though methylene chloride is not known to cause cancer in people, it has been shown to cause cancer in laboratory animals. Studies showed that breathing of methylene chloride by laboratory rats cause liver and lung cancers [7, p20]. No other health effects are likely for the levels of methylene chloride detected in ambient air around the site.

Groundwater

People living around the site have probably not been exposed to methylene chloride in groundwater as it has not been detected in any of the private wells adjacent to WMWI property. Methylene chloride was detected at low levels in two monitoring wells during the June 1990 and January 1991 off-site groundwater sampling. These levels were 2 and 1 µg/L and do not pose a health risk to people.

If the site was not cleaned up it is possible for methylene chloride levels in off-site groundwater to dramatically increase. On-site leachate was found to have a 4,200 µg/L methylene chloride level. This contamination could leave the site and cause elevated methylene chloride levels in off-site groundwater, and significantly increasing the health risks to residents around the site.

If methylene chloride concentrations in off-site groundwater were to increase to 34 µg/L (1 percent of the highest on-site groundwater concentration), people drinking this water over a lifetime would have a low increased risk of cancer. Ingesting low levels of methylene chloride has not been shown to cause cancer in people. Studies of laboratory animals ingesting methylene chloride have shown increases in liver and mammary cancers. People could also be exposed by inhaling methylene chloride vapors released from using contaminated water for washing and bathing purposes. Inhaling methylene chloride vapors over a lifetime also poses a low increased cancer risk. The health effects of inhaling methylene chloride are described above [7, p25].

Tetrachloroethylene (PCE)

Human exposure to tetrachloroethylene (PCE) may have occurred through ambient air contamination, but is unlikely to have happened as the result of contaminated groundwater.

Ambient Air

Nearby residents and workers at the site have possibly breathed PCE in the air. Ambient air testing around the site detected low levels of PCE. Air testing was not conducted near private residences, though airborne contamination of PCE has probably reached homes to the east of the site by following prevalent winds.

Ambient air testing at Muskego detected PCE at all seven sampling locations, which were taken around the perimeter of the site. Ambient air PCE concentrations detected were from 0.2 to 0.6 µg/m³. This is below typical background levels. Average background levels of PCE for urban and suburban areas are reported to be approximately 5 µg/m³, and 9 µg/m³ near emission sources [8, p80].

There are no known health effects for the level of PCE detected in ambient air around the site.

Groundwater

If PCE contaminated groundwater reaches private wells people could be exposed to the chemical in drinking water and indoor air. PCE has not been detected in any of the private wells adjacent to WMWI and Anamax property. PCE was detected in two wells during second round of off-site groundwater sampling, with a level of 1 µg/L found in both wells. This level of PCE does not pose a health risk.

Yet failure to clean the site might result in PCE contaminated groundwater leaving the site and reaching private water supplies. Levels of PCE in on-site groundwater was detected in one well at 550 µg/L. This level of contamination could have a significant impact on the health of people using this groundwater.

If PCE were to reach a concentration of 55 µg/L in groundwater (10 percent of highest level detected in on-site groundwater) it would pose a low increased risk of cancer to persons drinking contaminated water over a lifetime. This level exceeds the Wisconsin Groundwater Quality Enforcement Standard for PCE of 1 µg/L [40]. This standard was adopted based on the U.S. EPA level of an acceptable lifetime cancer risk [15, p304]. The Department of Health and Social Services determined that PCE "may reasonably be anticipated to be a carcinogen" [8, p4]. There are no conclusive studies concerning the cancer effects of PCE in humans, but studies of laboratory animals ingesting low levels of PCE have shown increases in liver cancer of mice [8, p35]. No other health effects are known for ingesting such a level of PCE.

Trichloroethylene (TCE)

Human exposure to trichloroethylene (TCE) may have occurred though ambient air contamination, but probably did not take place as the result of contaminated groundwater.

Ambient Air

Workers at the site and local residents may have breathed air contaminated with TCE. Air testing has not been conducted at private residences around the site, but airborne contamination of TCE has probably followed prevalent winds and reached homes to the east of the site.

Off-site ambient air testing around the site detected the presence of TCE at all seven sampling locations, which were situated around the perimeter of the site. Ambient air TCE concentrations covered the range from 0.1 to 0.4 µg/m³.

The levels of TCE detected in ambient air around the site are typical for a setting such as Muskego. Normal background TCE levels for urban and suburban areas are reported as 0.47 µg/m³, and a range of 0.01 to 2.43 µg/m³ near landfill sites [9, p80].

There are no known health effects for the levels of trichloroethylene detected in ambient air around the site.

Groundwater

People living around the site have not been exposed to groundwater contaminated with trichloroethylene. If contaminated groundwater were to reach nearby private wells people could be exposed to TCE in drinking water and indoor air. TCE has not been detected in any of the private wells adjacent to WMWI property.

TCE was detected during both rounds of off-site groundwater sampling. In the December 1988 round of off-site groundwater monitoring five wells showed a TCE contamination of 5.6 µg/L. In the June 1990 and January 1991 groundwater monitoring results, TCE was detected in five wells, in the range of 1 to 7 µg/L. These levels of TCE are not known to cause adverse health effects.

However, if the site was not cleaned up it is possible for TCE levels in off-site groundwater to dramatically increase. On-site leachate was found to have TCE at a concentration of 440 µg/L. This TCE contamination could be carried away from the site by groundwater, resulting in contamination of off-site groundwater. This could be drawn by private wells, significantly increasing the health risks to nearby residents.

If TCE levels in groundwater were to increase to 44 µg/L (10 percent of the highest level found in on-site groundwater), people drinking this water over the course of a lifetime could face no apparent increased risk of cancer. This level of TCE exceeds the Wisconsin Groundwater Quality Enforcement Standard of 5 µg/L [40], which was adopted in 1985 based on a previous U.S. EPA level of an acceptable lifetime cancer risk [15, p327] for TCE. It is unresolved whether or not TCE causes cancer in laboratory animals, and there is no evidence that TCE causes cancer in people. One mice study shows high levels of TCE to be associated with liver cancer [9, p35]. The U.S. EPA has since withdrawn its TCE cancer risk level for further review. There are no known health effects in people from exposure to this level of TCE contamination.

Vinyl Chloride

People living around the site have not been exposed to vinyl chloride contaminated groundwater as it has not been detected in any of the private wells adjacent to WMWI property. Vinyl Chloride was detected in one off-site groundwater monitoring well. If groundwater contaminated with vinyl chloride reaches private wells, people could be exposed to the chemical in drinking water and indoor air.

Vinyl chloride was detected in a single well (P64C) during both rounds of off-site groundwater sampling. During the June 1990 and January 1991 rounds of groundwater monitoring, this well showed detections of vinyl chloride at 7 and 5 µg/L. Ingesting water at these levels would exceed ATSDR's chronic Minimal Risk Level of 0.00002 mg/kg/day.

A low increased risk of cancer is posed by the lifetime use of water contaminated with 7 µg/L of vinyl chloride. Vinyl chloride is classified by the U.S. EPA as a known human carcinogen [29, p3-31]. The risk of vinyl chloride exposure is from both drinking and inhaling vapors released in the domestic use of contaminated water. Increases in human liver cancer has been attributed to long-term, low-level occupational exposure from vinyl chloride. Laboratory rats studies have shown that inhalation of low-level vinyl chloride causes in liver and lung cancers [29, p3-31]. Low levels of vinyl chloride ingested by laboratory rats has the non-cancer health effect of causing liver changes [10, p36].

Chromium

People around the site were probably not exposed to groundwater contaminated with chromium. Chromium was not detected in groundwater sampled from any of the private wells adjacent to WMWI property. Both trivalent and hexavalent chromium were detected in one of 24 monitoring wells during the January 1991 round of off-site groundwater sampling. The sample from this well showed chromium at 27 µg/L.

People who drank water contaminated with a 27 µg/L level of chromium could develop a type of skin rash or dermatitis. There are no other known health effects from ingestion of this level of chromium [2].

If the site were not cleaned up the potential exists for chromium levels in off-site groundwater to dramatically increase. Chromium was detected in on-site leachate at a level of 3,610 µg/L. Groundwater could carry this contamination off the site, which could significantly impact groundwater quality. This contaminated water could be drawn by nearby private wells, and ingested by household members. If chromium (the hexavalent isomer) in groundwater reached a level of 360 µg/L (10 percent of the leachate level) it could adversely affect the health of people. This level of chromium has been shown in mice to cause liver changes and harm the male reproductive organs and [2, p46 & p43]. There are no other known health effects from this level of chromium in drinking water.

Lead

Lead is a chemical of concern because residents of two nearby households were probably exposed to lead in their drinking water at levels which could affect their health. No other nearby private wells have shown lead contamination. It is not known if the lead found in the water supply of these two households is caused by the site.

People living in two households south of the site probably drank water contaminated with lead. Information is not available to completely assess how lead in drinking water affected the people living in these households.

Groundwater sampled during the 1982 testing of the two private wells (PW-5 & PW-6) was contaminated with lead, 300 µg/L and 100 µg/L, respectively [39, Appendix K2]. These results exceed the Wisconsin Public Health Groundwater Enforcement Standard of 50 µg/L and EPA's Action Level of 15 µg/L [40]. Water from PW-6 was analyzed again in 1984 with no detection of lead. There was no further testing of water from these wells for contaminants. Municipal water was brought to these residences in 1986. The RI/FS indicates these wells were abandoned, however the date of abandonment is not given. Sampling information is unavailable about how and where the samples were collected. It is possible plumbing could have contributed the lead detected in the samples.

It is difficult to estimate how these people were affected by the potential exposure to lead. We do not know the number and types of individuals who consumed lead-contaminated water. This is important because certain people are more susceptible to lead, particularly young children. Additionally it is not possible to determine the length of time the contaminated water was consumed and if lead concentrations varied with time. We do not know when people began using an alternative water source after lead was detected in their water.

Low-level lead exposures can hinder the development and functioning of the central nervous system, affect blood components, slightly alter liver functions. Lead may also cause harm to the reproductive system. Laboratory animal studies have shown lead to suppress the immune system [6].

If the site were not cleaned up the potential exists for lead levels in off-site groundwater to increase significantly. Off-site groundwater testing found lead in eight wells during the January 1991 round of groundwater monitoring. The highest level detected of lead was 5 µg/L. However, lead was detected in on-site leachate at a level of 19,100 µg/L. Groundwater could carry this lead contamination off the site, which could impact groundwater quality. This contaminated water could be drawn by nearby private wells, and ingested by people using this water.

B. Health Outcome Data Evaluation

A review of health outcome data is appropriate when there is evidence of people who have been exposed to contaminants at levels which could lead to a increase in rates of death or illness. "Health Outcome Data" refers to records of death and/or disease. A review of health outcome data might also be appropriate if there are reports of unusual clusters or higher-than-expected levels of specific diseases near a site.

The levels of exposure to VOC chemicals of concern are too low to initiate any studies of death and illness. The lead detected in two nearby private wells was at a level which could adversely affect the health of those exposed, but at the time these exposures occurred, such health outcomes were probably not reported into a health data collection system. Typically lead exposure is directly determined by analysis of blood of the affected individual. In the event additional Muskego Sanitary Landfill data becomes available which shows local residents exposed to a much higher level of contaminants, such a study may be desirable.

C. Community Health Concerns Evaluation

The health concerns raised by community members, who live adjacent to Muskego Sanitary Landfill, are addressed below.

• Can people become ill from breathing contaminated dust which might be generated if the existing caps are removed during the remediation process?

  Any dust released during the clean-up process would probably not contain contaminants because cover materials would be clean. The remediation alternative proposed by the U.S. EPA includes capping the entire site [27]. The proposed action will upgrade the existing caps. Some of the existing cap material may be removed, stockpiled, and reused on the new cover. Contaminated material will probably not be exposed and dust control measures will probably be implemented.

• Can underground gas from the site and cause an explosive hazard in private buildings?

  Methane gas is being generated at the site, but landfill gas monitoring shows venting and extraction measures are apparently preventing gas migration away from the site. The proposed clean-up will further reduce gas levels on and around the site. The U.S. EPA proposed remediation alternative includes implementing an active landfill gas control system in the Old Fill and Southeast Fill areas and an In-Situ Vapor Extraction system for the Non-contiguous Fill area. The presence and migration of methane gas was first noted at the site in 1984. A gas extraction system has been operating along the western edge of the Old Fill Area since 1984 to alleviate methane gas buildup and migration. There are 47 gas probes and vents installed at various locations around the site to monitor gas levels.

• Will the sampling of existing private wells continue quarterly as planned?

  The U.S. EPA Remedial Project Manager stated that quarterly monitoring of selected private wells will continue.

• Is there the possibility of contamination to any new wells that would be dug in the area?

  There are no existing privave wells around the Muskego Sanitary Landfill drawing contaminated groundwater. If a well was installed near the site it would probably draw clean groundwater. Yet there is the chance that this water could become contaminated in the future. However DNR regulations prohibit the drilling of a new well within 1,200 feet of a landfill [41].

• Is surface water carrying contaminants from the Superfund site to other people's land?

  If surface water were carrying contaminants away from the site, the concentrations would probably be at levels which are not of a health concern. Some surface water leaves the site via the drainage ditch running along the access road to the Anamax facility. It is possible that contaminants could travel along this pathway and leave the site. Sediment from the drainage ditch and nearby wetlands was tested and showed low-levels of contaminants. These contaminants were at levels well below those that would pose a health hazard.

• Can contaminants reach gardens and orchards, particularly when surface water is used for irrigation?

  Surface water from a wetland has been reported to be used for agricultural purposes. One family adjacent to the site occasionally uses water in the wetland to irrigate trees on their property. Based on the drainageway sediment testing, it is possible that some slightly contaminated surface water and/or sediment might be drawn for irrigation purposes. However the results of sediments testing shows these compounds to be at levels which are not of concern.

• Is it possible for contaminants from the site to harm livestock (cows, sheep, poultry) and pets (dogs, cats, horses) and, indirectly, human health?

  The only way livestock and pets may be exposed to off-site contaminants from Muskego Landfill is by breathing contaminated air. The concentrations of VOCs detected in ambient air are too low to pose a threat to the animals. These chemicals are not known to become concentrated in animal's bodies.

• Is there a possibility of contamination to the deep well on Anamax property? (This is a deep, high capacity well drawing from a separate aquifer far below the contaminated aquifers, which the City of Muskego considers as a feasible municipal water supply.)

  The Remedial Investigation does not provide enough information to answer this question. The City of Muskego should consider addressing this matter to a qualified hydrogeological professional for a proper response.

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