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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). Theuse of the term "On-Site" refers to locations found within one or more of these areas. Thehazardous contaminants have been detected on-site in the refuse, leachate, basal soils,ambient air, and groundwater of these areas. Contaminant concentrations in leachate fromthe 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 inleachate at higher levels.

One on-site well exhibited the highest concentrations of specific VOCs in any media foundon the site. Groundwater from this well (E136), found within the "L-shaped" boundary ofthe 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

Sampler Source of information listed under References
Sampling Locations a - Old Fill Area
b - New Fill Area
c - Non-Contiguous Fill Area
d - Off-Site
e - Anamax Sludge Lagoons
f - Private Wells
Definitions Indicators: A minimum of pH, Conductivity, Alkalinity, Hardness, Dissolved Solids, and certain inorganic compounds.
Metals: Total Heavy Metals
PPCB: Pesticides & Polychlorinated Biphenyls
SVOC: Semi-Volatile Organic Compounds
VOC: Volatile Organic Compounds

Air

Leachate head/gas vent air samples were collected on-site in 1988. See the discussion ofoff-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 Reportas "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.

MChemicals in Leachate Muskego Sanitary Landfill Waukesha County, Wisconsin

Compound Maximum Level
Detected
1990 Analysisa
(µg/l)

Old Fill         SE Fill

Maximum Level
Detected
1989 Analysisb
(µg/l)

Old Fill         SE Fill


Benzene 24 5 1,300 5,000
1,2-Dichloroethylenec - 400 120 420
Methylene Chloride 4,200 3,200 400 3,200
Tetrachloroethylene - - - -
Trichloroethylene - 41 440 440
Vinyl Chloride 12 - - 65
Chromium 816 70 3,610 182
Lead 2,460 297 19,100 323


Sources: a. Warzyn, Inc. Remedial Investigation/Feasibility Study - Muskego Sanitary Landfill Site, Technical Memorandum No. 2, Report 13527. Madison, Wisconsin: Warzyn, January 1991, Appendix J-1 (Leachate Analytical Results).
  b. Warzyn, Inc. Remedial Investigation/Feasibility Study - Muskego Sanitary Landfill Site, Technical Memorandum No. 1, Report 13527. Madison, Wisconsin: Warzyn, April 1989, Table 18 & Table 21.
  c. Concentration reported is total for all isomers.


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) tohave 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, AppendixG]. This well (PW-1) was abandoned on June 25, 1990 [36, p3-17].

Table 3.

Chemicals Detected in Off-Site Groundwater Monitoring Wells December 1988 Muskego Sanitary Landfill Waukesha County, Wisconsin

 
Compound Minimum
Detected
(µg/L)
Maximum
Detected
(µg/L)
Frequency
of
Detection
ComparisonValue
(µg/L)

Benzene 1.2 * 7.8 * 2/5 1.2 a
1,2-Dichloroethane 1.6 * 3.7 * 3/5 0.4 a
Tetrachloroethylene - 8.6 * 1/5 5.0 b
Trichloroethylene - 5.6 * 1/5 5.0 b

        * 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 MemorandumNo. 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 andcharacterize the contaminant migration routes [35, p1-2]. Groundwater samples werecollected 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 ingroundwater. Three of these compounds (benzene, tetrachloroethylene, andtrichloroethylene) were detected at levels which exceed the Wisconsin Public HealthGroundwater Enforcement Standards [40]. Results of the analyses were consideredestimated because of a reduced level of quality control was employed during the samplingand analyses [35, p3-22].

In June 1990 testing of off-site groundwater was conducted to further determine the extentof groundwater contamination along potential migration pathways. Water samples werecollected 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 includeprivate wells. Samples were collected from points along potential migration routes[36, p2-11]. Analyses were conducted for VOCs, SVOCs, pesticides, and inorganicchemicals. In January 1991 groundwater samples were collected from 24 off-sitemonitoring 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
June 1990 Sampling January 1991 Sampling  
Compound Minimum
Detected
(µg/L)
Maximum
Detected
(µg/L)
Frequency
of
Detection
Minimum
Detected
(µg/L)
Maximum
Detected
(µg/L)
Frequency
of
Detection
Comparison
Value
(µg/L)
Benzene 3 * 21 * 5/23 1 13 * 6/24 1.2 a
1,2-Dichloroethane 1 9 * 6/23 2 4 3/24 5.0 a
1,2-Dichloroethylene 1 9 8/23 2 12 8/24 70.0 b
1,2-Dichloropropane 2 * 5 * 3/23 2 * 5 * 3/24 0.5 c
Methylene Chloride - 2 1/23 1 2 2/24 4.7 a
Trichloroethylene 2 6 * 5/23 1 7 * 5/24 5.0 d
Vinyl Chloride - 7 * 1/23 - 5 * 1/24 0.2 e
Chromium - 0 0/23 - 27 1/24 50.0 f
Lead 1 2 2/23 2 5 8/24 15.0 d

    * 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 heavymetals (Table 4). Pesticides and polychlorinated biphenyls were not detected in these results. Contaminants which exceed the Wisconsin Public Health Groundwater Quality EnforcementStandard [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 nocontaminants were detected. Samples were collected in January, May, and August of 1991,by U.S. EPA and WMWI [263739]. Two of the wells sampled provide the sole source ofwater on the property. Four other wells are at locations which are connected to themunicipal water system. It is reported that well water at these four locations is not used fordrinking, cooking, or bathing. These six wells are apparently in the path of contaminatedgroundwater. In December 1991 the DNR recommended to the U.S. EPA that groundwaterand 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 weretaken at three locations (SD1 to SD3) in drainages east of the Old Fill and Southeast Fillareas (Figure 3). At each location samples were collected from the top one inch of thesurface sediment over a one square foot area. Samples were collected with stainless steelspoons 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 werefound in sediments near the site boundary during the first round [36, p4-16]. Samples werecollected from five new locations around the site (SD4 to SD8). Refer to Figure 3 for thelocation of sampling points. Two sampling locations (SD4 & SD6) were in the easternwetland. Sample SD8 was intended to be a background sample and was collected from adrainage 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 SD4and 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 nodetections of contaminants in the sample from SD2. Though the results show relatively lowlevels 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" ofcontaminants [36, p3-25]. In round two there were no contaminants detected in samplescollected from SD5, SD6, and SD7. Heavy metals, PCBs (polychlorinated biphenyls), andpesticides were not detected in these samples.

Ambient Air

Between October 30 & November 1, 1988, ambient air samples were collected at sevenlocations around the perimeter of the site [35, p2-20]. The placement of these monitoringstations was not reported. The samples were collected by drawing air through a charcoalresin at a controlled rate of flow over a 24-hour period. These samples were analyzed forVOCs and the results are shown in Table 5. Though testing of the samples were qualifiedbecause the analytical laboratory exceeded the specified sample holding times, there was ahigh frequency of detection for VOC compounds. No information was provided about winddirection, wind speed, temperature, or humidity during the sampling. The RI/FS did reportthat 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 1988Muskego Sanitary Landfill Waukesha County, Wisconsin

Compound Minimum
Detected
(µg/m3)
Maximum
Detected
(µg/m3)
Frequency
of
Detection
Comparison
Value
(µg/m3)

Benzene 1.7 * 8.1 * 7/7 0.1 a
Methylene Chloride 3.6 * 50.4 * 7/7 2.1 a
Tetrachloroethylene 0.2 0.6 7/7 4.1 b
Trichloroethylene 0.1 0.4 7/7 n/a

    * 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-sitefill areas. The concentrations of the VOCs in landfill gases are much higher than theirconcentrations in air around the site. Vapor samples were collected from a leachate-headwell and gas vent, and the results are shown in Table 6.



Table 6.

Chemicals Detected in Leachate-head Well/Gas Vent Vapor (11/8/88) Muskego Sanitary Landfill Waukesha County, Wisconsin

  
Compound Level
Detected
at LH12
(µg/m3)

Benzene 1,404
1,2-Dichloroethylenea 244
Methylene Chloride 4,871
Tetrachloroethylene 2,292
Trichloroethylene 3,438
Vinyl Chloride 3,438

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 andBig Bend zip codes for any previously reported toxic chemicals. The TRI is searched inorder to investigate any other sources of environmental contamination near the site. Certainmanufacturers are required to report to the U.S. EPA of releases to the environment of over300 hazardous chemicals. This reported information is entered into the computerized TRIsystem. The TRI search did not list any reports of hazardous substance releases ortransferrances 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 theobjectives described in the Quality Assurance Project Plan (dated 12/87). The ability of theDOH to make valid conclusions is dependent, to some extent, on the amount and quality ofdata provided. These quality assurance and quality control measures were to be followedduring field sampling and measurements, the chain of custody activities, laboratoryanalytical procedures, and data reporting.

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

E. Physical And Other Hazards

Landfill Gas

Landfill gas was detected at Muskego Sanitary Landfill in 1984 and controls (extraction andventing system) were installed. Methane, a large constituent of landfill gas, is generatedfrom the decomposition of organic material found in refuse deposited at the site. Landfillgas is a potential hazard because it can migrate away from the site, move into the basementsof nearby buildings and homes, and accumulate up to explosive levels. A spark from afurnace, 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 tomonitor the situation. It was reported in 1988 by the RI/FS contractor that the migration ofmethane 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 nearbybuildings 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 toVOC contamination carried away from the site by ambient air. However questions about thesampling process and results make it difficult to draw conclusions about these potentialhuman exposures. Three nearby private wells were shown to contain site-relatedcontamination, but these wells are no longer in use. No other nearby private wells have beenshown to be contaminated. If the site were not cleaned-up then contaminated groundwater inthe vicinity of the site could migrate away and reach these private wells. DOH assumes thatdirect physical contact with contaminated refuse and leachate is unlikely to occur becauseeach site is covered with fill and is capped. Furthermore there have been no reports of thesematerials being uncovered at the site. Physical contact with leachate might occur as a resultof the extraction process, however its handling and removal is tightly controlled. Directphysical exposure with hazardous substances could result from contact with contaminatedambient 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 likelybreathed 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 analyzinglaboratory held the samples beyond the recommended holding times. Despite analyzedsamples exceeding the holding times, VOCs were still detected. It is possible that samplesinitially contained higher concentrations of VOCs than the analyses revealed.

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

Additional data is necessary to accurately assess the extent of past and present humanexposures to ambient air contamination originating from the site. The ambient air samplingresults were taken over a single 24-hour period and do not fully characterize the extent ofairborne contamination around the site and at nearby homes. Dispersion would probablycause air contamination at nearby homes to be lower than the levels detected at the siteperimeter. Sampling of ambient air during various atmospheric conditions at these homeswould 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 notsite-related. Past exposures could then be estimated from present exposure.

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

Groundwater

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

Three nearby private wells were abandoned after showing contamination. People probablydrank water contaminated with lead in two of these households (PW-5 & PW-6). Peopleliving in one household (PW-6) were probably exposed (ingestion, dermal contact andinhalation) to water contaminated with 1,2-dichloroethylene. No other private wells in thearea 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 becauseall contaminated water supply wells around the site have been abandoned. However thepotential remains for the water supplied by other private wells to become contaminated.

Hazardous chemicals detected in site leachate (VOCs, SVOCs and heavy metals) are theprimary source of contaminants entering the groundwater. Most contaminants observed inoff-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 gravelaquifer, and can carry contamination away from the site [36, p4-1]. However the movement ofcontaminated groundwater in the shallow aquifer under the site is complicated by theimpermeable layers of clay/till and sand/gravel (refer to Site Geology on page 5). Theselayers affect the way contamination leaves each fill area. Migration of contaminants awayfrom the Old Fill area occurs as leachate enters the groundwater which flows northwest overthe impermeable lacustrine clays and glacial tills. As the contaminated groundwater reachesthe edge of the clay and glacial till, it flows down into the outwash sand/gravel aquifer andflows back to the south under the site. At some places within the Old Fill area where theimpermeable clay/till material does not exist, contaminants migrate directly down into theoutwash sand and gravel aquifer. The contaminants at the Non-Contiguous Fill area enterdirectly into the outwash sand and gravel aquifer as no impermeable layer is present. Contaminated groundwater movement away from the Southeast Fill area is impaired bynatural 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]. Thefurthest extent of contamination from the site is 800 feet south (E-135) and 400 feetsoutheast (P-64) away. These 36 private wells may be affected if contaminated groundwatercontinues to move away from the site. WMWI plans to continue quarterly monitoring ofselected nearby private wells.

Despite the availability of municipal water, private wells are still used in the immediatevicinity of the site. There are 35 private wells east, southeast, and south of the site whichdraw water from the outwash sand and gravel aquifer. Ten of these homes continue to obtainall drinking water from private wells. Fifteen of nearby homes are connected to municipalwater and the owners have not abandoned their wells. The well water at these homes isreportedly used for agricultural and/or livestock purposes and is not drank by people or usedfor domestic purposes. DNR regulations prohibit new well drilling within 1,200 feet of alandfill 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 potentiallyaffected wells.

An estimated 25 people could be exposed to hazardous chemicals if contaminatedgroundwater was to reach the ten households that still use private wells as their sole sourceof water (assuming 2.5 people per home). The chemicals detected in groundwatermonitoring wells of potential health concern are VOCs (benzene, 1,2,-dichloroethane,1,2-dichloropropane, tetrachloroethylene, trichloroethylene, and vinyl chloride). The peoplecould be exposed by ingesting contaminated water, breathing from vapors released duringthe 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 fromthe site in sediment, but a potential pathway exists for human exposure. Contaminated soilscould be carried off-site in sediment media. The RI/FS contractor stated that "sediment is apotential migration pathway for contaminants" originating from the site which entereddrainages 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 WMWIrepresentative stated during the October 1991 site visit that runoff tends to remain onproperty owned by either WMWI or the Anamax Rendering Company. However, somerunoff originating from the site probably flows from the southeastern wetland, though aculvert under Janesville Road, and into a separate wetland on private property south ofJanesville road. While contaminated sediment and/or surface water may travel south ofJanesville Road, neither sediment nor surface water from this private wetland has beentested.

Contaminants were detected in sediment collected from the off-site wetland located southeastof the site and the drainways leading to the wetland. Low-levels of toluene and1,1-dichloroethane, and trace levels of other VOCs and SVOCs were detected. Though thetesting of wetland surface water for contaminants has not been conducted, it is unlikely thatthe low-level contaminants in sediment could migrate into surface water and have asubstantial affect on water concentrations.

One household adjacent to the site reported using water from the southeastern wetland toirrigate their orchard during dry summer months [16]. Contaminated sediment could be takenup with surface water during pumping and watering of the fruit trees. These two VOCscould be released into the air during watering or taken up by fruit trees. A person wateringthe trees might breath these vapors. However these two VOCs were detected at such lowlevels that even if large amounts of sediment was drawn while watering the trees and allVOCs were released, the highest possible exposure would not be of a health concern. It isunlikely 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 pathwaybecause a pathway for exposure exists, however contaminants detected in sediment are not ata 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

  Groundwater Ambient Air
Chemical Has Human
Contact
Occurred?
Maximum
Level
Detected
(µg/l)
Has Human
Contact
Occurred?
Maximum
Level
Detected
(µg/m3)

Benzene No 21 Likely 8.1
1,2-Dichloroethane No 9  
1,2-Dichloroethylene Yes 16  
1,2-Dichloropropane No 5  
Methylene Chloride No 2 Likely 50.4
Tetrachloroethylene No 1 Likely 0.6
Trichloroethylene No 7 Likely 0.4
Vinyl Chloride No 7  
Chromium No 27  
Lead Yes 300  

Benzene

Human exposure to benzene may have occurred through ambient air contamination, but isunlikely 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 aroundthe perimeter of the site. Concentrations ranged from 1.7 to 8.1 µg/m3. Though ambientair sampling has not been performed adjacent to private residences, airbornecontamination has likely followed the prevalent wind direction, reaching homes to theeast 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 periodcould suppress the immune system [1, p25]. The immune system is reported to be one ofthe most sensitive human organs to benzene toxicity [1, p13]. The U.S. EPA classifiesbenzene as a known human carcinogen [28]. People who breath air contaminated withbenzene at 8.1 µg/m3 for a lifetime could face a low-increased risk of cancer. Benzene isknown to cause leukemia in workers exposed over several years to low levels in air, andhas been shown to cause several types of cancer in laboratory animals [28].

Groundwater

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

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

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

1,2-Dichloroethane

If groundwater contaminated with 1,2-dichloroethane (1,2-DCA) reaches nearby privatewater supplies, people could be exposed to 1,2-DCA in drinking water, indoor air and bathwater. Human exposure to 1,2-dichloroethane probably has not occurred around the site, asit 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 groundwatermonitoring and in 3 of 24 wells during the January 1991 groundwater monitoring. Thehighest level of 1,2-DCA detected in monitoring wells was 9 µg/L, which exceeds theWisconsin 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 inpeople 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 ofspecific 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 supplyprobably happened at one private residence near the site. People were likely exposed to1,2-dichloroethylene (1,2-DCE) in drinking water and indoor air. The number of individualsaffected and length of 1,2-DCE exposure is not known. The home was torn down and thewell 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 1984groundwater 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-DCEcontamination may have been higher before the water supply was tested. Therefore it is notfeasible to plot levels of contamination or human exposure through time.

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

The long-term health effects on humans and animals from ingesting low levels of 1,2-DCEare unknown. There have been no reports of adverse effects to health in humans or animalsexposed to low concentrations of 1,2-DCE [4]. If 1,2-DCE were to reach other watersupplies, 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 peoplecould be exposed to the chemical in drinking water, indoor air, and bath water. Peoplearound the site have probably not been exposed to 1,2-dichloropropane as it has not beendetected in any private wells. 1,2-Dichloropropane has been found in monitoring wellsaround 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 groundwatermonitoring and in 3 of 24 wells during the January 1991 monitoring. The level detectedranged 2 to 5 µg/L for both rounds of monitoring.

People drinking groundwater contaminated with this level of 1,2-dichloropropane have noapparent, measurable increased cancer risk. 1,2-Dichloropropane has been categorized as aprobable human carcinogen by the U.S. EPA. Though 1,2-dichloropropane is not known tocause cancer in people, studies of laboratory mice have shown 1,2-dichloropropane to causeliver tumors [29, p3-13]. There are no other health effects known for the levels of1,2-dichloropropane detected at the site.

Methylene Chloride

Human exposure to methylene chloride may have occurred though ambient air contaminationbut 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. Airtesting has not been conducted near private residences, though airborne contamination ofmethylene chloride has probably followed prevalent winds and reached homes to the eastof the site.

Off-site ambient air testing at Muskego detected the presence of methylene chloride at allseven sampling locations located around the site perimeter. Ambient air methylenechloride 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 thannormal. 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 havea low increased risk of cancer. The U.S. EPA classifies methylene chloride as a probablehuman 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 breathingof methylene chloride by laboratory rats cause liver and lung cancers [7, p20]. No otherhealth 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 ingroundwater as it has not been detected in any of the private wells adjacent to WMWIproperty. Methylene chloride was detected at low levels in two monitoring wells duringthe June 1990 and January 1991 off-site groundwater sampling. These levels were 2 and1 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-sitegroundwater to dramatically increase. On-site leachate was found to have a 4,200 µg/Lmethylene chloride level. This contamination could leave the site and cause elevatedmethylene chloride levels in off-site groundwater, and significantly increasing the healthrisks 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 waterover a lifetime would have a low increased risk of cancer. Ingesting low levels ofmethylene chloride has not been shown to cause cancer in people. Studies of laboratoryanimals ingesting methylene chloride have shown increases in liver and mammarycancers. People could also be exposed by inhaling methylene chloride vapors releasedfrom using contaminated water for washing and bathing purposes. Inhaling methylenechloride vapors over a lifetime also poses a low increased cancer risk. The health effectsof inhaling methylene chloride are described above [7, p25].

Tetrachloroethylene (PCE)

Human exposure to tetrachloroethylene (PCE) may have occurred through ambient aircontamination, 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. Ambientair testing around the site detected low levels of PCE. Air testing was not conducted nearprivate residences, though airborne contamination of PCE has probably reached homes tothe east of the site by following prevalent winds.

Ambient air testing at Muskego detected PCE at all seven sampling locations, whichwere taken around the perimeter of the site. Ambient air PCE concentrations detectedwere from 0.2 to 0.6 µg/m3. This is below typical background levels. Averagebackground levels of PCE for urban and suburban areas are reported to be approximately5 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 thechemical in drinking water and indoor air. PCE has not been detected in any of theprivate wells adjacent to WMWI and Anamax property. PCE was detected in two wellsduring second round of off-site groundwater sampling, with a level of 1 µg/L found inboth wells. This level of PCE does not pose a health risk.

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

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

Trichloroethylene (TCE)

Human exposure to trichloroethylene (TCE) may have occurred though ambient aircontamination, 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 airbornecontamination of TCE has probably followed prevalent winds and reached homes to theeast of the site.

Off-site ambient air testing around the site detected the presence of TCE at all sevensampling locations, which were situated around the perimeter of the site. Ambient airTCE 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 asMuskego. Normal background TCE levels for urban and suburban areas are reported as0.47 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 ambientair around the site.

Groundwater

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

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

However, if the site was not cleaned up it is possible for TCE levels in off-sitegroundwater to dramatically increase. On-site leachate was found to have TCE at aconcentration of 440 µg/L. This TCE contamination could be carried away from the siteby groundwater, resulting in contamination of off-site groundwater. This could be drawnby 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 levelfound in on-site groundwater), people drinking this water over the course of a lifetimecould face no apparent increased risk of cancer. This level of TCE exceeds theWisconsin Groundwater Quality Enforcement Standard of 5 µg/L [40], which wasadopted 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 laboratoryanimals, and there is no evidence that TCE causes cancer in people. One mice studyshows high levels of TCE to be associated with liver cancer [9, p35]. The U.S. EPA hassince withdrawn its TCE cancer risk level for further review. There are no known healtheffects in people from exposure to this level of TCE contamination.

Vinyl Chloride

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

Vinyl chloride was detected in a single well (P64C) during both rounds of off-sitegroundwater sampling. During the June 1990 and January 1991 rounds of groundwatermonitoring, this well showed detections of vinyl chloride at 7 and 5 µg/L. Ingesting water atthese 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 7µg/L of vinyl chloride. Vinyl chloride is classified by the U.S. EPA as a known humancarcinogen [29, p3-31]. The risk of vinyl chloride exposure is from both drinking and inhalingvapors released in the domestic use of contaminated water. Increases in human liver cancerhas 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 liverand lung cancers [29, p3-31]. Low levels of vinyl chloride ingested by laboratory rats has thenon-cancer health effect of causing liver changes [10, p36].

Chromium

People around the site were probably not exposed to groundwater contaminated withchromium. Chromium was not detected in groundwater sampled from any of the privatewells adjacent to WMWI property. Both trivalent and hexavalent chromium were detectedin one of 24 monitoring wells during the January 1991 round of off-site groundwatersampling. 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 atype of skin rash or dermatitis. There are no other known health effects from ingestion ofthis level of chromium [2].

If the site were not cleaned up the potential exists for chromium levels in off-sitegroundwater to dramatically increase. Chromium was detected in on-site leachate at a levelof 3,610 µg/L. Groundwater could carry this contamination off the site, which couldsignificantly impact groundwater quality. This contaminated water could be drawn bynearby private wells, and ingested by household members. If chromium (the hexavalentisomer) in groundwater reached a level of 360 µg/L (10 percent of the leachate level) itcould adversely affect the health of people. This level of chromium has been shown in miceto cause liver changes and harm the male reproductive organs and [2, p46 & p43]. There are noother 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 probablyexposed to lead in their drinking water at levels which could affect their health. No othernearby private wells have shown lead contamination. It is not known if the lead found in thewater supply of these two households is caused by the site.

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

Groundwater sampled during the 1982 testing of the two private wells (PW-5 & PW-6) wascontaminated with lead, 300 µg/L and 100 µg/L, respectively [39, Appendix K2]. These resultsexceed the Wisconsin Public Health Groundwater Enforcement Standard of 50 µg/L andEPA's Action Level of 15 µg/L [40]. Water from PW-6 was analyzed again in 1984 with nodetection 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 wellswere abandoned, however the date of abandonment is not given. Sampling information isunavailable about how and where the samples were collected. It is possible plumbing couldhave 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-contaminatedwater. This is important because certain people are more susceptible to lead, particularlyyoung children. Additionally it is not possible to determine the length of time thecontaminated water was consumed and if lead concentrations varied with time. We do notknow when people began using an alternative water source after lead was detected in theirwater.

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

If the site were not cleaned up the potential exists for lead levels in off-site groundwater toincrease significantly. Off-site groundwater testing found lead in eight wells during theJanuary 1991 round of groundwater monitoring. The highest level detected of lead was 5µg/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 impactgroundwater quality. This contaminated water could be drawn by nearby private wells, andingested 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 havebeen exposed to contaminants at levels which could lead to a increase in rates of death orillness. "Health Outcome Data" refers to records of death and/or disease. A review of healthoutcome 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 ofdeath and illness. The lead detected in two nearby private wells was at a level which couldadversely affect the health of those exposed, but at the time these exposures occurred, suchhealth outcomes were probably not reported into a health data collection system. Typicallylead exposure is directly determined by analysis of blood of the affected individual. In theevent additional Muskego Sanitary Landfill data becomes available which shows localresidents 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 SanitaryLandfill, are addressed below.

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

    Any dust released during the clean-up process would probably not contain contaminantsbecause cover materials would be clean. The remediation alternative proposed by theU.S. EPA includes capping the entire site [27]. The proposed action will upgrade theexisting caps. Some of the existing cap material may be removed, stockpiled, and reusedon the new cover. Contaminated material will probably not be exposed and dust controlmeasures 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 andextraction measures are apparently preventing gas migration away from the site. Theproposed clean-up will further reduce gas levels on and around the site. The U.S. EPAproposed remediation alternative includes implementing an active landfill gas controlsystem in the Old Fill and Southeast Fill areas and an In-Situ Vapor Extraction systemfor the Non-contiguous Fill area. The presence and migration of methane gas was firstnoted at the site in 1984. A gas extraction system has been operating along the westernedge 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 monitorgas levels.

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

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

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

    There are no existing privave wells around the Muskego Sanitary Landfill drawingcontaminated groundwater. If a well was installed near the site it would probably drawclean groundwater. Yet there is the chance that this water could become contaminated inthe future. However DNR regulations prohibit the drilling of a new well within 1,200feet 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 wouldprobably be at levels which are not of a health concern. Some surface water leaves thesite via the drainage ditch running along the access road to the Anamax facility. It ispossible that contaminants could travel along this pathway and leave the site. Sedimentfrom the drainage ditch and nearby wetlands was tested and showed low-levels ofcontaminants. These contaminants were at levels well below those that would pose ahealth hazard.

  • Can contaminants reach gardens and orchards, particularly when surface water isused 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 ontheir property. Based on the drainageway sediment testing, it is possible that someslightly contaminated surface water and/or sediment might be drawn for irrigationpurposes. However the results of sediments testing shows these compounds to be atlevels 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 MuskegoLandfill is by breathing contaminated air. The concentrations of VOCs detected inambient air are too low to pose a threat to the animals. These chemicals are not known tobecome concentrated in animal's bodies.

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

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


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