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PUBLIC HEALTH ASSESSMENT

TRI-COUNTY LANDFILL WASTE MANAGEMENT OF ILLINOIS
SOUTH ELGIN, KANE COUNTY, ILLINOIS



ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS

The tables for this section list the contaminants of concern. These chemicals will be further evaluated in the remaining sections of this Public Health Assessment to determine if they pose a threat to public health. The listing of a contaminant on the following tables does not necessarily mean that it poses a threat to public health. The selection of these contaminants is based on the following factors:

  1. Concentrations of contaminants in the various on- and off-site media of concern.
  2. Data quality, both in the field and laboratory, as well as the sampling plan design.
  3. Comparison of contaminant concentrations and background levels with health assessment comparison values for both carcinogenic and noncarcinogenic endpoints(discussed further below).
  4. Community health concerns.

Comparison values for the Public Health Assessment are levels that are used to select contaminants for further evaluation. These values, prioritized below, include Environmental Media Evaluation Guides (EMEGs), Cancer Risk Evaluation Guides (CREGs), Reference dose Media Evaluation Guide (RMEGs), Lifetime Health Advisories (LTHAs), and Maximum Contaminant Levels (MCLs). If a site-related contaminant is found at levels above any of these comparison values or if no comparison values exist for the chemical, it will be investigated further in the remaining sections of the Public Health Assessment to determine if it poses a significant threat to public health. Known or suspected carcinogens for which no carcinogenic comparison value exists will also be listed as a contaminant of concern and will be evaluated in the remaining sections of this Public Health Assessment.

EMEGs are comparison values developed for chemicals that are relatively toxic, frequently encountered at NPL sites, and present a potential for human exposure. They are derived to protect the most sensitive members of a population (e.g., children) and are not cut-off values, but rather comparison values. They do not consider carcinogenic effects, chemical interactions, multiple route exposure, or other media-specific routes of exposure. They are conservative values designed to protect the public.

CREGs are estimated contaminant concentrations based on a risk of one excess cancer in a million people exposed to a chemical over their lifetimes (70 years). These are also conservative values designed to protect sensitive members of the population.

RMEGs are estimates of a daily oral or inhalation exposure to a particular chemical that is unlikely to produce any noncarcinogenic adverse health effects over a lifetime. They are conservative values designed to protect sensitive members of the population.

LTHAs are drinking water concentrations an individual consumes for 70 years without experiencing any noncarcinogenic health effects. These numbers contain a margin of safety to protect sensitive members of the population. These values are considered only if no EMEG, CREG, or RMEG are available for the chemical.

MCLs have been established by the USEPA for public water supplies to reduce the chances of adverse health effects from contaminated drinking water. These standards are well below levels for which health effects have been observed and take into account the financial feasibility of achieving specific contaminant levels. These are enforceable limits which public water supplies must meet. These values are considered only if no EMEG, CREG, RMEG, or LTHA are available for the chemical.

A. On-site Contamination

    1.    Air

The concentrations of any on-site airborne contaminants at the Tri-County or Elgin Landfills are unknown. The active Woodland Landfill produces odors which are frequently strong on-site. These odors may confound any study of on-site airborne contaminants.

    2.    Groundwater

On-site groundwater data are available for shallow, intermediate, and deep monitoring wells, as well as on-site private wells (Figures 4 and 6). Some of the monitoring wells are between the Prairie Path and the Woodland Landfill and are technically off-site, however, because of their close proximity to the site boundary (200 feet or less), their data are included with the on-site monitoring results.

    a.    Shallow Monitoring Wells

For June 1989 to December 1990, organic contaminants in shallow monitoring wells are given in Table 1. Volatile organic contaminants of concern include benzene, 2-butanone, dibenzofuran, 1,1-dichloroethene, tetrachloroethene, trichloroethene, and vinyl chloride. Semivolatile organic chemicals of concern include bis(2-ethylhexyl) phthalate, naphthalene, and pentachlorophenol. The pesticide, aldrin, was a contaminant of concern. There are no comparison values for chloroethane, 1,1-dichloroethane, 2-hexanone, 2-methylnaphthalene, 4-methylphenol, and phenanthrene, so these chemicals will also be evaluated further in this document. No PCBs were found in shallow monitoring wells (WW Engineering and Science, 1991a).

For June 1989 to December 1990, the concentrations of inorganic chemicals in shallow monitoring wells are given in Table 2. Antimony, arsenic, barium, beryllium, cadmium, fluoride, lead, manganese, mercury, nickel, thallium, and vanadium were the contaminants of concern. Beryllium, however, was also a chemical of concern in background monitoring wells.

    b.    Intermediate Monitoring Wells

For June 1989 to November 1990, the concentrations of organic chemicals in intermediate monitoring wells are given in Table 3. Benzene, bis(2)ethylhexyl phthalate, 1,2-dichloroethene, and vinyl chloride were the contaminants of concern. There are no comparison values for chloroethane, 1,1-dichloroethane, and 1,1,1-trichloroethane, so these chemicals will be further evaluated in this document. 1,1,1-trichloroethane was found in background monitoring wells at the same concentration found in on-site ones. No PCBs were found in intermediate monitoring wells (WW Engineering and Science, 1991a).

For June 1989 to November 1990, the concentrations of inorganic chemicals in intermediate monitoring wells are given in Table 4. Antimony, arsenic, barium, cadmium, chromium, fluoride, lead, manganese, and nickel were the contaminants of concern. Beryllium was at levels of concern only in background monitoring wells, while fluoride was at levels of concern in background and on-site monitoring wells.

    c.    Deep Monitoring Wells

For June 1989 to September 1990, chloromethane was the only chemical of concern in deep monitoring wells Table 5. No PCBs or pesticides were found in deep monitoring wells (WW Engineering and Science, 1991a).

For June 1989 to November 1990, the concentrations of inorganic chemicals in deep monitoring wells are given in Table 6. Arsenic was a contaminant of concern in background and on-site wells, beryllium was a chemical of concern in background wells, and fluoride was a contaminant of concern in monitoring wells.

    d.    On-site Private Wells

For September to October 1990, the concentrations of organic chemicals in private on-site bedrock wells are given in Table 7. Benzene and 1,2-dichloroethane were the contaminants of concern. Comparison values are not available for chloroethane and 1,1-dichloroethane, and these chemicals will be evaluated further in this Public Health Assessment. No PCBs or pesticides were found in on-site private wells (WW Engineering and Science, 1991a).

For September to October 1990, the concentrations of inorganic chemicals in on-site private wells are given in Table 8. In bedrock wells, nickel and thallium were the contaminants of concern. In the wells of unknown depth (unknown aquifer wells), antimony and thallium were the chemicals of concern.

    3.    Soil

For May 1989 to October 1990, organic chemicals in on-site surface soil (Figure 7) are given in Table 9. No volatile compounds were above the comparison values. Of the semi-volatile compounds, benz(a)anthracene and N-nitroso-di-N-propylamine exceeded their comparison values. No comparison values are available for many of the chemicals in Table 9, and they will be further evaluated in this document. No PCBs were found in on-site surface soils (WW Engineering and Science, 1991a). Many of the chemicals found in surface soil have also been found in on-site groundwater (Tables 1 to 8).

For May 1989 to September 1990, the concentrations of inorganic chemicals in surface soil (Figure 7) are given in Table 10. Antimony, cadmium, and nickel were contaminants of concern in only on-site surface soil, but arsenic, barium, beryllium, chromium, manganese, and selenium were above the comparison values in on-site and background surface soil.

For May 1989 to October 1990, the concentrations of organic chemicals in subsurface soil borings are given in Table 11. Sampling locations are shown in Figure 6. Benz(a)anthracene and beta-benzene hexachloride were above their comparison values in on-site soil, while N-nitrosodiphenylamine was a contaminant of concern only in background soil. For many of the chemicals, no comparison values are available, and they will be further evaluated in this document.

For May 1989 to October 1990, the concentrations of inorganic chemicals in on-site soil borings (Figure 6) are given in Table 12. Antimony and cadmium were above their comparison values only in on-site soil. Arsenic, beryllium, chromium, and manganese were contaminants of concern on-site and background soil. Barium was above its comparison value only in background soil. For some of the chemicals, no comparison values are available, and they will be further evaluated in this document.

In October 1990, several test pits were dug in the northwestern part of the Elgin Landfill, where electromagnetic surveys suggested large amounts of metal, potentially drums of chemicals, may be buried (Figure 8). Large numbers of buried drums were not found, but soil samples were taken from these test pits. Organic chemicals found in this soil are given in Table 13. PCBs and bis(2-ethylhexyl)phthalate were the only chemicals of concern. For many of the compounds, however, no comparison values are available, and they will be further examined in this document.

For October 1990, the concentrations of inorganic chemicals found in the on-site test pits are given in Table 14. The levels of antimony, arsenic, barium, beryllium, cadmium, chromium, lead, manganese, and nickel exceeded their comparison values.

    4.    Surface Water and Sediments
      a.    Surface Water

For May 1989 to September 1990, the concentrations of organic chemicals in on-site surface water (Drainage Ditch and on-site depressions; Figure 9) are given in Table 15. In the Drainage Ditch, which is adjacent to the Prairie Path, carbon disulfide was the only organic contaminant of concern. In on-site depressions, hexachloroethane was the only organic chemical of concern. There is no comparison value for 4-methylphenol (Drainage Ditch), and it will be further evaluated in this document.

For May 1989 to September 1990, the concentrations of inorganic chemicals in on-site surface water (Drainage Ditch and on-site depressions; Figure 9) are given in Table 16. Arsenic, beryllium, and vanadium were contaminants of concern in the Drainage Ditch and on-site depressions. Ammonia, barium, lead, manganese, and nickel were chemicals of concern only in the Drainage Ditch.

      b.    Sediments
For May 1989 to September 1990, the levels of organic chemicals in on-site sediments (Drainage Ditch and on-site depressions; Figure 9) are given in Table 17. Benz(a) anthracene and PCBs were contaminants of concern in on-site depressions, but no organic chemicals exceeded their comparison values in the drainage ditch.

For May 1989 to September 1990, the concentrations of inorganic chemicals in on-site sediments (Drainage Ditch and on-site depressions) are given in Table 18. Arsenic, beryllium, chromium and manganese were contaminants of concern in the Drainage Ditch and on-site depressions. The barium concentration in the Drainage Ditch was above its comparison value, while the same was true for antimony and cadmium in on-site depressions.

B.    Off-site Contamination

    1.    Air

The concentrations of-site airborne chemicals are unknown. The active Woodland Landfill produces odors which can be noticeable in the area and may confound any study of airborne contaminants.

    2.    Groundwater

For September to October 1990, the concentrations of organic compounds in off-site private sand and gravel wells or wells of unknown depth are given in Table 7. Well locations are given in Figure 4. No organic chemicals were found in the wells of unknown depth. In one sand and gravel well, No. 10, bromodichloromethane, chloroform, dibromochloromethane, and bis(2-ethylhexyl)phthalate were above their comparison values. According to WW Engineering and Science (1991a), this well was chlorinated shortly before sampling, which likely accounts for the presence of bromodichloromethane, chloroform, and dibromochloromethane. Phthalates may come from plastic pipes.

For September to October 1990, background and non-background data are available for inorganic chemicals in off-site private sand and gravel wells (Table 19). Beryllium (well 10) and thallium (wells 3, 9, 12, and 17) were contaminants of concern in non-background wells, while nitrate + nitrates exceeded the comparison value in background wells. Lead was at an elevated level in well 6.

For September to October 1990, background and non-background data are available for inorganic chemicals in off-site bedrock wells (Table 19). Arsenic (wells 7, 19, and 21) and thallium (well 21) were contaminants of concern in non-background bedrock wells. Lead was detected at high concentrations in well 7.

For September to October 1990, nonbackground data are available for inorganic chemicals in off-site wells of unknown depth (Table 19). In these wells, no inorganic chemicals were found above their comparison values.

    3.    Soil

It is unknown whether off-site soil has been contaminated by chemicals from the landfill.

    4.    Surface Water and Sediments
      a.    Surface Water

For May 1989 to September 1990, the concentrations of organic compounds in off-site surface water (Unnamed Tributary and Woodland Landfill Pond) are given in Table 15. Sampling locations are given in Figure 9. In the unnamed tributary, no organic chemicals were present above their comparison values upstream or downstream of the site. However, no comparison value is available for 4-methylphenol, and it will be further evaluated in this document. In the Woodland Landfill Pond, hexachloroethane was a contaminant of concern.

For May 1989 to September 1990, the concentrations of inorganic chemicals in off-site surface water are given in Table 16. None of these chemicals exceeded their comparison values in the unnamed tributary or Woodland Landfill Pond.

    b.    Sediments

For May 1989 to September 1990, the levels of organic chemicals in off-site sediments (unnamed tributary, background marsh, and Woodland Landfill Pond) are given in Table 17. Sampling locations are given in Figure 9. No organic chemicals were found above their comparison values in the Woodland Landfill Pond. In general, chemicals were at higher locations upstream of the landfill and in the background marsh than downstream of it. This indicates that there is another unknown source of contamination upstream. Many of the detected chemicals are polycyclic aromatic hydrocarbons, which are common combustion products. Benz(a)anthracene was a contaminant of concern in upstream and downstream samples from the unnamed tributary, as well as in the background marsh. For many of the detected chemicals, no comparison values are available, and they will be further examined in this document.

For May 1989 to September 1990, the concentrations of inorganic chemicals in off-site sediments (unnamed tributary, background marsh, and Woodland Landfill Pond) are given in Table 18. Arsenic, beryllium, and manganese were the contaminants of concern at the unnamed tributary (upstream and downstream), background marsh, and Woodland Landfill Pond. Chromium was a chemical of concern in sediments of the unnamed tributary (upstream and downstream) and background marsh. Antimony was above its comparison value only at the Woodland Landfill pond. Barium and cadmium were contaminants of concern only in the background marsh. Comparison values were not available for many of the chemicals, so they will be further evaluated in this document.

C.    Quality Assurance and Quality Control

WW Engineering and Science (1991a) provided a good description of quality assurance/quality control (QA/QC) methods, which appeared adequate.

In the RI, WW Engineering and Science (1991a) did not examine the geology or groundwater flow off-site, and they also failed to examine the effect of diversion of shallow and intermediate groundwater flow by the clay sidewall of the Woodland Landfill.

This made it more difficult to evaluate the likelihood of potential or further contamination of off-site private and municipal wells. This is discussed further in the pathways section of this document.

On-site and off-site, the RI (WW Engineering and Science, 1991a) did not examine the continuity of the red silty clay layer or the hydrology of the deeper till units. This makes it difficult to evaluate the likelihood of contamination (or further contamination) of deep groundwater.

In the RI (WW Engineering and Science, 1991a), on-site surface soil samples were not taken along the Prairie Path, where public exposure is most likely.

In the baseline risk assessment (WW Engineering and Science, 1991b), the estimated risk of inhaling arsenic in dust was accidently reported as 2/10 instead of 2/10,000. This estimate was based on modeling results. The validity of any model depends on the assumptions used in it. ATSDR does not consider modeling results a substitute for sampling, and the modeling results were not used in this document.

However, the IDPH did rely on the information in other documents. It assumed that adequate QA/QC measures were followed regarding chain-of-custody, laboratory procedures, and data reporting. The analyses, conclusions, and recommendations in this health assessment are valid only if the referenced documents are complete and reliable.

D.    Physical and Other Hazards

There are few obvious physical hazards on the Tri-County Landfill, which consist of some exposed pieces of metal and concrete. Before it was mostly covered, the Elgin Landfill had a considerable amount of exposed construction rubble (primarily concrete), which was a physical hazard.

Fire and explosion dangers on- and off-site have not been evaluated. The landfill produces gas, but its composition and flammability are unknown. Methane is a common component of landfill gas, but it is unknown whether it occurs at explosive concentrations on-site or has migrated off-site. Carbon disulfide has been found on-site, and its vapors are flammable and can be explosive.

PATHWAYS ANALYSES

A hazardous chemical can affect people only if they contact it through an exposure pathway at a sufficient concentration to cause a toxic effect. This requires a source of exposure, an environmental transport medium, a route of exposure, and an exposed population. A pathway is complete if all of its components are present and people were exposed in the past, are currently being exposed, or will be exposed in the future. If (1) parts of a pathway are absent, (2) data are insufficient to determine if it is complete, or (3) exposure may occur at some time (past, present, future), then it is a potential pathway. The exposure pathways at this site are summarized in Table 20.

A.    Completed Exposure Pathways
  1. Groundwater

Groundwater pathways are complete for only currently contaminated on- and off-site private wells (past, present, future). The number of people exposed to contaminants in private wells is unknown.

The source of contamination for groundwater is the waste in the landfill. Groundwater which contacts this waste can then become polluted. Groundwater can enter the wastes via subsurface flow or infiltration of precipitation. Infiltration of precipitation is most likely in areas where the landfill cap is thin, water tends to accumulate, or areas with sandy soil. The movement of chemicals through groundwater is determined by the geology of the site and surrounding area (Figures 10, 11a-h, 12, and 13). Groundwater flows readily through sand, but clay inhibits its movement. The geology of the area consists of glacial till approximately 100 feet thick overlying dolomite bedrock. The upper portion of the till is sand and gravel approximately 25 feet thick, which was mined and mostly removed from the site. This till forms a shallow aquifer, with water present 15 to 20 feet below the general land surface. Under the sand and gravel is 10 to 20 feet of gray silty clay, which frequently has discontinuous, interbedded, water-bearing sand and gravel lenses and stringers. The layer of gray silty clay thins out near BP33A, and possibly also in the northwestern part of the Tri-County Landfill. Below the gray silty clay is a layer of silt 8 to 20 feet thick, which often has discontinuous lenses of sand and gravel 0 to 10 feet thick above, below, and within it. Under this deposit is 20 to 30 feet of reddish brown silty clay. Although it is continuous under the Woodland Landfill and some geologists believe it also completely underlies the Tri-County and Elgin ones, its continuity is not entirely certain. Thus, it is unknown if it will protect lower aquifers from contamination. Discontinuous, interbedded sand and gravel lenses and stringers also occur in this layer of silty clay. According to Waste Management, Inc., they are less common in this layer than in the lower one; however, according to the Illinois State Geological Survey (ISGS), they are more numerous in the lower layer. The sand layers in the various strata would tend to increase the lateral movement of groundwater. Under the layers of silty clay is sand and gravel 25 to 50 feet thick, which forms the lower till aquifer. The next layer is Silurian dolomite, and approximately the upper 25 feet of this formation is fractured and comprises the shallow bedrock aquifer. It is hydraulically connected to the lower till aquifer.

Just to the west of the Tri-County and Elgin Landfills, and partially under the Woodland one, is the buried Newark Bedrock Valley (Figures 14 and 15). This valley has extensive deposits of sand and gravel on its floor and is an important source of water for many private wells and two nearby communities, South Elgin and Valley View. The water in the Newark Aquifer is believed to move in a southwesterly direction along it, but this is not certain. Furthermore, the direction of groundwater movement may be modified locally by well cones of depression. Northeast of the border of the map in Figure 15, the Newark Bedrock Valley becomes shallow and thins out. It is believed to end one to two miles northeast of the border of the map, in Section 19, T41N, R9E.

Because of suburban sprawl and problems with widely used deep bedrock aquifers, reliance on the Newark Aquifer will likely increase in the future. For example, due to problems with naturally occurring radium in their deep groundwater supplies, the cities of Batavia, Geneva, and St. Charles (Figure 16) cannot expand their interconnected municipal water supply until they find a source of acceptable water. At present, radium cannot be economically removed from water, aside from the 85% reduction given by water treatment, so dilution is the only practical way to solve the problem. St. Charles has drilled one high-yielding well into the Newark Aquifer, and more will probably follow. The other alternative for water is the Fox River, which is being used by Elgin to solve a barium problem and Aurora to dilute radium. Fox River water, however, is high in nitrates, which must be diluted by groundwater. Aurora and Elgin mix Fox River and deep water to obtain acceptable levels of all dissolved substances.

In any case, the Newark Aquifer is important and its possible future contamination is of concern. Well logs also indicate that the two layers of silty clay are thin to absent south of the site (Figures 17 and 18).

Under the Tri-County and Elgin Landfills, the top of the gray silty clay is between 730 and 742 feet in elevation (Figure 19). Under most of the landfills, the water table is above the silty clay, so it is likely in contact with the wastes (Figures 19 and 20). The direction of groundwater flow was determined from water elevation measurements in the shallow monitoring wells, which are screened in the sand and gravel layer or refuse, and are above or at the top of the gray silty clay layer. In the shallow groundwater, the direction of flow is generally to the southwest in the Tri-County Landfill, but near and under the Elgin Landfill, it flows to the north or northwest (Figures 20 and 21). Localized areas of higher water levels often correspond with surface depressions, particularly on the Elgin Landfill and the northwestern part of the Tri-County Landfill. Evidently, surface water accumulates in these depressions and migrates downward into the groundwater, causing a rise in the water table elevation.

About 200 feet west of the Prairie Path, the clay side wall of the Woodland Landfill extends down into the lower reddish-brown silty clay. This will block the westward flow of shallow groundwater. From the groundwater contours (Figures 20 and 21), along most of the Elgin Landfill, the groundwater will flow to the north after being deflected. North of the Elgin Landfill, the sidewall of the Woodland Landfill turns toward the west, which would allow the groundwater to again flow to the northwest. However, the off-site flow of groundwater has not been investigated, so the actual direction of movement is unknown.

Along most of the Tri-County Landfill, the shallow groundwater is deflected toward the south. This is of concern because south of the site, the clay layers under it are thin to absent (Figures 17 and 18). Well levels on-site indicate the groundwater tends to move downward toward the bedrock (WW Engineering and Science, 1991a). Consequently, after being diverted southward by the side wall of the Woodland Landfill, contaminants in the shallow aquifer may move into the area south of the site where sand and gravel predominates. They could then migrate downward into the lower aquifers, contaminating private wells and the Newark Aquifer.

The direction of flow in intermediate groundwater was determined by water elevations in intermediate monitoring wells. These wells are screened in sand and gravel lenses in or near the bottom of the gray silty clay or in the silt layer below. From the information provided in WW Engineering and Science (1991), it was uncertain whether any of the wells penetrated into the reddish-brown silty clay. WW Engineering and Science (1991) found that under most of the site, the direction of intermediate groundwater flow was to the southwest and south-southwest (Figures 22 and 23). Again, water moving toward the southwest will be deflected to the south by the side wall of the Woodland Landfill. This water could then enter the area south of the site that has thin to absent clay confining layers (Figures 17 and 18). The contaminants could then move downward into the deeper aquifers, leading to the contamination of downgradient private wells and the Newark Aquifer. Because there are few intermediate wells north of the Elgin Landfill, the direction of flow under and north of this part of the site is uncertain. The intermediate groundwater in this area may move toward the north or northwest.

The direction of groundwater flow in the shallow dolomite aquifer was determined from deep monitoring wells (Figures 24 and 25). In August 1989, groundwater was flowing to the southwest and south-southwest. In February 1991, the direction of flow had changed to the west and west-northwest. According to WW Engineering and Science (1991), this was caused by dewatering operations at the Woodland Landfill. After these operations are finished, the groundwater flow will presumably return to its previous direction. The flow of water in the shallow dolomite aquifer is not stopped by the side wall of the Woodland Landfill. Instead, the flow will pass under it.

Site contaminants are present in on-site private wells, which serve on-site businesses. Consequently, the clay layers are not sufficiently continuous or confining to prevent contamination of the shallow dolomite aquifer. During construction of the adjacent Woodland Landfill, three abandoned wells were found and plugged. If abandoned wells were present in the Tri-County or Elgin Landfills and were not properly sealed, they could have enabled shallow groundwater contaminants to reach deeper aquifers. Elevated arsenic concentrations in the three wells (wells 7, 19, and 21) and lead levels in one well (well 7) immediately south of the site may have come from on-site contamination in the bedrock aquifer. Alternatively or in addition, arsenic or lead which moved southward in shallow or intermediate groundwater may have reached the area south of the site where the clay layers are thin or absent. The contaminants then could have moved downward into the deeper aquifers. The lead in well 6 is probably not site-related because well 1, between it and the landfills, is unaffected. Lead in water can come from lead pipes or solder.

People using contaminated water can be exposed to it via ingestion, inhalation, or dermal contact. Volatile chemicals can evaporate from water, particularly during showering. These volatile compounds can then be inhaled. It is unknown whether any of the contaminated on- or off-site water supplies are used for showering. Volatile organic compounds with low water solubility are the most likely to evaporate at concentrations of concern. Inorganic compounds would not reach levels of concern during showering. It is not known how many people are exposed to water from the contaminated wells, if any of this water is consumed, or how long it has been contaminated. The contaminated wells serve businesses, so the exposure of children is unlikely. However, fetuses could be exposed if pregnant women use the water. Furthermore, in the past, a person lived at an on-site business in an attached apartment (Seely, 1992). Consequently, the past, present, and future exposure of children to contaminated on-site groundwater is possible.

Some private wells have non-site-related contaminants. Nitrates + nitrites can come from a malfunctioning septic system. One well which had recently been chlorinated had bromodichloromethane, chloromethane, and dibromochloromethane, which are common byproducts of chlorination. The concentrations of these three chemicals should decline rapidly with time, so prolonged exposure is not expected. This makes health effects from these three chemicals unlikely. People can be exposed to non-site-related chemicals via the same human exposure pathways (past, present, future).

    2.    Soil

The soil pathways are complete for only surface soil. The source of contamination for surface soil is the waste of the landfill. Chemicals in the wastes can reach surface soil in several ways. As previously described, the wastes can pollute groundwater, which can then reach the surface as leachate seeps, contaminating the soil. In particular, this has occurred on the southern side of the Tri-County Landfill. Surface soil can also be polluted if it is mixed with wastes.

Many chemicals have been found in on-site surface soil. It is difficult to determine what level of any soil contaminant is of health concern because many factors affect the toxicity of chemicals in soil. These factors affect how tightly chemicals are absorbed to soil and include (1) clay content and type, (2) cation exchange capacity, (3) moisture level, (4) organic matter content, (5) pH, (6) soil particle size distribution, (7) temperature, and (8) the water and octanol solubilities of the compound of concern (Harris, 1972; Bailey and White, 1970; Harris, 1966). Chemicals which are tightly bound by soil are not easily absorbed by organisms, and this greatly reduces their toxicity. For example, for crickets, Harris (1966) found that soil organic matter had a large effect on insecticide activity. Heptachlor, diazanon, Memacide, DDT, and parathion were 209, 283, 546, 965, and 1132 times less toxic, respectively, in a muck soil with 64.4% organic matter than in quartz sand (Harris, 1966). This occurred because organic matter adsorbs compounds with low water solubility (e.g., many insecticides, PCBs), reducing their bioactivity. Soils with increased clay content and cation exchange capacity (increased primarily by clay and organic matter content) bind cations such as heavy metals and reduce their availability for uptake by organisms. In soils with high pH, most heavy metals are less soluble and less toxic. However, some metals are more soluble at high pH. In acidic soils (or the stomach), many heavy metals are more soluble and more toxic. Because of these effects, it is difficult to evaluate possible health effects of contaminants in soils and sediments. While ATSDR has established comparison values for soil, they assume 100% absorption after ingestion. This is extremely unlikely, so these comparison values are conservative. However, the soil comparison values do not take dermal absorption into account, which may underestimate health risks. People can be exposed to contaminants in on-site surface soil. Soil pathways are complete for on-site workers for the past, present, and future, because it is known they have been on-site and will be on it in the future. For the public, soil pathways are complete for the past, because it is known they have entered the site. On-site people would be exposed to these contaminants via incidental ingestion and dermal contact. It is not known how many people are or were exposed to contaminated soil.

B.    Potential Exposure Pathways
  1. Air

All air pathways are potential ones because the concentrations of airborne contaminants are unknown (past, present, future). Consequently, it is unknown whether any airborne chemicals have been, are, or will be at levels of concern.

The wastes of the landfills are the source of any airborne contamination. As previously discussed, surface soil can be contaminated, and areas of bare soil can produce airborne dust. The Tri-County Landfill is mostly well-vegetated, which would inhibit the production of airborne dust. Dirt bike and other ATV tracks have been seen on this landfill (Seely, 1992; WW Engineering and Science, 1991b), and these vehicles would increase the production of airborne dust. Any on-site construction (future) would also increase the production of airborne dust. In addition, volatile chemicals could evaporate from leachate, soil, soil gas, or surface water. By exposing more highly contaminated material, on-site construction could increase the evaporation of volatile chemicals (future). Before a cover was placed on the Elgin Landfill, its bare surface would have enhanced the production of airborne dust. Conversely, after it was covered, the production of airborne dust should have been considerably reduced, assuming that the cap material was uncontaminated. Some organic compounds can volatilize from the wastes and become soil gas, which can move through the soil and reach the surface. These compounds can then become airborne. Volatile chemicals can also evaporate from leachate, contaminated surface soil, or polluted surface water (described in the Surface Water subsection). The addition of the cap to the Elgin Landfill probably reduced the volatilization of chemicals from it, particularly if the cap material was clay with low permeability. Any airborne contaminants produced on-site could be carried off-site by wind. Concentrations will decrease with distance downwind of the source.

Exposure to airborne contaminants could occur on- or off-site. People could be exposed to contaminants via the inhalation or dermal absorption of volatile compounds, as well as the ingestion or inhalation of dust. Whether particles are ingested or inhaled depends on where in the respiratory system they are deposited, and this depends on particle size. Inhaled particles over five microns in size tend to deposit in the nasopharyngeal area (nasal passages, throat, and larynx). Particles in the nasal passages drain into the throat, where they are ingested. Particles in the larynx are removed by cilia and ingested. Particles one to five microns in size tend to deposit in the bronchial region of the lung. They are removed from the lung by cilia and ultimately ingested. Particles under one micron in size can penetrate deeply into the alveoli of the lungs and are not easily removed.

People potentially exposed to on-site airborne contaminants include on-site workers, trespassers, and Prairie Path users (past, present, future). People potentially exposed to off-site airborne chemicals include off-site residents, off-site workers, and Prairie Path users (past, present, future).

Landfill gas and volatile chemicals from the soil could enter buildings. Landfill gas is entering Al's Truck Repair, an on-site business (Seely, 1992); however, the concentration of contaminants in it are unknown. Consequently, it is unknown whether workers at the business are exposed to chemicals at levels of health concern. Consequently, this is a potential pathway. While it is more likely that landfill gas will enter on-site buildings, it could also migrate to off-site ones. People inside affected buildings would then inhale the contaminants. In businesses, this exposure would probably be limited to a normal work day and work week, while in residences, it could potentially occur for 24 hours a day - seven days a week. However, in the past, a person lived at an on-site business in an attached apartment (Seely, 1992), so exposure at a business could potentially be for 24 hours a day - seven days a week.

It is not known how many people may be exposed to on- or off-site airborne contaminants.

    2.    Groundwater

In the future, currently uncontaminated downgradient private or municipal wells could be polluted by chemicals from the site. Additional chemicals or higher concentrations of present contaminants could also be transported to currently affected wells. Because the flow of groundwater off-site is largely unknown, it is not certain which wells may become contaminated or more affected. However, those south and southwest of the site are the downgradient ones if water in the shallow dolomite aquifer continues in the same direction off-site. In addition, the north to northwest movement of shallow and intermediate groundwater in the northern portion of the site could potentially contaminate other wells. Because connections between shallow, intermediate, and deep groundwater north and northwest of the site are unknown, the possible future contamination of wells in these directions are uncertain. If more wells become contaminated, people using them could be exposed to these pollutants via ingestion, inhalation, or dermal contact.

In the future, homes or additional businesses could be constructed on-site. If they are served by private wells, people using them could be exposed to site contaminants via ingestion, inhalation, or dermal contact.

It is not known how many people are served by downgradient private wells, so it is uncertain how many people may be affected in the future. Contamination of the South Elgin or Valley View municipal wells would expose about 7223 and 2112 residents, respectively.

    3.    Sediments

The source of contamination for sediments is the wastes of the landfill. Landfill contaminants can reach sediments through leachate seeps (from contaminated groundwater), erosion of contaminated soil, or deposition from surface water. In addition, the unnamed tributary and background marsh have non-site-related contaminants of unknown origin. While surface water may move sediments of the Drainage Ditch and unnamed tributary, those of the on-site depressions and Woodland Landfill Pond will most likely remain in-place.

People can be exposed to contaminants in on-site sediments. This exposure is potential because it is unknown whether it has occurred. On-site workers and trespassers could be exposed to contaminants in sediments via incidental ingestion and dermal contact. Airborne exposure to contaminated dust or chemicals that volatilized from sediments is a potential pathway which was discussed in the Air subsection above.

People could be exposed to contaminants in off-site sediments in the unnamed tributary and background marsh. Children playing in the stream or marsh would be the people most likely exposed. Exposure could occur via ingestion or dermal contact.

The number of people who may be exposed to on- or off-site sediments is unknown.

    4.    Soil

Trespassers could be exposed to chemicals in on-site soil via incidental ingestion or dermal contact. The inhalation of airborne dust was discussed in the air subsection above. Some young children (usually six years old or less) exhibit pica behavior and eat dirt. However, the site is currently far enough away from homes that it is unlikely such small children would enter it. The one exception is parents with small children using the Prairie Path may stop along it and their kids may eat dirt. However, with the adjacent active Woodland Landfill, this part of the Prairie Path is not an attractive place to stop. Consequently, this exposure may be negligible (past, present, future until the Woodland Landfill is closed). Farmland in the vicinity is being developed at a rather rapid rate. Consequently, in the future, it is probable that the farmland east and north of the landfills will be used for homes. This would make trespassing, especially by children, more likely. In the future, on-site homes may be constructed. The construction may bring deep contaminants to the surface, where exposure could occur. The exposure of small children to soil contaminants in on-site homes would be likely and would be highest in areas with bare soil.

It is unknown whether off-site soils have been contaminated. This contamination could occur from airborne deposition or erosion and surface water transport. People could be exposed to off-site soil contamination via ingestion or dermal contact. The area to the east of the site is mostly farmland and most of the land south of it is marsh. Consequently, daily exposure to any chemicals in these soils is unlikely. If the farmland became contaminated, chemicals could be translocated into crops. If the soil of the farmland is contaminated and homes are built on it, their yards may have elevated levels of any such compounds.

The number of people who may be exposed to known or potential contaminants in on- or off-site soil is unknown.

Surface water can dissolve chemicals and move suspended sediments. Some chemicals are more easily dissolved and carried by water, while others are less soluble and tend to be carried on suspended sediments. The surface contours of the site are shown in Figure 10. The ravine shown on the Elgin Landfill has been filled, and its cap is now relatively flat on top of the landfill. On the eastern side of the Tri-County Landfill, water flows into a shallow ditch. On the western side of this landfill, surface water flows into a low area just east of the Prairie Path. The slope in both areas is relatively flat, with a general, gradual slope to the south. Along most of the site, this slope is so gradual that little runoff probably occurs. Because of the sandy soil, most of the surface water probably infiltrates. The southern slope of the Tri-County Landfill is steep and eroded. Water in this area goes into the marsh and drainage ditch in the southern part of the site. The drainage ditch empties into the unnamed tributary, which could then become contaminated (sediments and surface water).

On-site workers and trespassers could be exposed to on-site surface water in on-site depressions or the drainage ditch via ingestion or dermal contact, with dermal contact more likely for on-site workers. While surface water of the unnamed tributary has not been affected by the site, it could be affected in the future if the amount of leachate flowing through the drainage ditch increased. This could occur if erosion of the cap causes increased leachate production. Consequently, exposure to contaminants in off-site surface water could occur in the future. Children playing in the unnamed tributary would be the most likely affected. However, ingestion of surface water would probably be infrequent, making health effects from exposure to surface water unlikely.

The number of people potentially exposed to contaminants in on- or off-site surface water is unknown.

PUBLIC HEALTH IMPLICATIONS

A.    Toxicological Evaluation

To evaluate potential health effects, the estimated exposure doses to site-related compounds have been compared with health effects information in the literature, primarily ATSDR Toxicological Profiles. ATSDR and USEPA have developed chemical-specific guidelines for evaluating the potential for adverse health effects of chemicals in air, water, and soil. ATSDR has developed Minimum Risk Levels (MRLs) to evaluate non-cancerous health effects. A MRL is an estimate of the daily human exposure to a contaminant below which non-cancerous adverse health effects are unlikely to occur. The exposure is expressed as milligrams of chemical per kilogram of body weight per day (mg/kg/d). MRLs are developed for both the oral and inhalation routes of exposure. They are also developed for different lengths of exposure, such as acute (14 days or less), intermediate (15 to 365 days), and chronic (over 365 days). An USEPA Reference Dose (RfD) is an estimate of the daily exposure (mg/kg/d) to the general public that is likely to be without an appreciable risk of deleterious noncancerous effects during a lifetime. The USEPA has also developed health advisories for exposure to drinking water for periods of one-day, ten-day, longer-term, and lifetime exposures to non-carcinogens. The USEPA also evaluates the potential of a chemical to cause carcinogenic (cancer) effects over a lifetime. To do this, they have estimated cancer slope factors for certain chemicals with sufficient toxicological information on cancerous effects. These cancer slope factors are estimates of the potency of a chemical to cause cancer and are used to estimate the cancer risk of specific doses. These risk estimates, however, are extremely conservative and are meant to protect susceptible members of the public. There is a 95% probability the actual risk is no higher, it is probably lower, and it may be zero. Furthermore, cancer risk estimates are extrapolated to low doses from high dose animal or human (usually occupational exposure) studies. This approach is somewhat controversial. Some researchers believe body repair mechanisms can handle low doses, and that higher ones are needed to cause cancer. Some people also question the validity of high to low dose extrapolation. Until more information on carcinogenesis becomes available, USEPA takes the conservative approach that there is no threshold and any exposure to a carcinogen carries a finite risk.

In the exposure estimate calculations, for drinking water, consumption was one liter per day for children and two liters per day for adults. Soil ingestion rates were 5000 milligrams per day for pica children and 100 milligrams per day for adults. Body weights were 10 kilograms for children and 70 kilograms for adults. For residents, daily exposure was assumed.

    1.   Organic Compounds
      Aldrin

Aldrin is an insecticide which was a chemical of concern in only on-site shallow monitoring wells. It can be absorbed after ingestion, inhalation, or dermal contact. Noncancerous effects are not expected from the concentrations present on-site. In mice, chronic oral exposure to aldrin increased the incidence of liver cancer. In rats, cancer of the adrenal and thyroid glands have been observed after oral exposure (ATSDR, April 1994a). Using the available toxicological information, USEPA has developed a cancer slope factor for aldrin, which can be used to estimate the cancer risk from a given dose. The estimated lifetime risk of drinking water with 0.05 ppb, the maximum on-site concentration, is less than that of drinking water from a chlorinated municipal water supply. Consequently, consuming aldrin on-site would not result in an unacceptable risk. Furthermore, as previously discussed, these risk estimates are extremely conservative.

    Benzene

Benzene was a chemical of concern in on-site monitoring and private bedrock wells. It can be absorbed after inhalation, ingestion, or dermal contact. Most of the observed health effects have been observed after inhalation exposure, and, unfortunately, little information is available after exposure via other routes. Non-cancerous effects would not be expected at the concentrations found on-site. There is sufficient evidence that benzene can cause leukemia after inhalation, but it is uncertain whether it can cause cancer after oral or dermal exposure (ATSDR, April 1994b). While leukemia has been seen in rats after oral/gavage exposure, the type of leukemia is different from the one observed in humans. The kind of leukemia observed in humans is rare in rodents (ATSDR, April 1994b). Using the animal data, USEPA derived a cancer slope factor which can be used for estimating cancer risk. For the maximum concentration in on-site groundwater, the estimated lifetime risk from ingestion would be less than the cancer risk of drinking from a chlorinated public water supply. Consequently, drinking on-site water should not result in an unacceptable cancer risk. Furthermore, as previously discussed, these risk estimates are conservative and may overestimate the actual risk.

    bis(2-Chloroethyl)ether

This compound was a chemical of concern in only on-site shallow monitoring wells. It can enter the body after ingestion, inhalation, or dermal contact. It can cause liver cancer in mice (ATSDR, August 1990a), so it may also be able to cause it in people. Based on the animal data, USEPA has developed a slope factor which can be used to estimate cancer risk at a given dose. The estimated lifetime risk of drinking water with the maximum on-site concentration, 8 ppb, is greater than the risk of drinking from a municipal water supply. Consequently, drinking shallow on-site groundwater may result in an unacceptable cancer risk. However, as previously discussed, these risk estimates are extremely conservative, and the actual risk may be lower.

    Benzyl Alcohol

Benzyl alcohol was found in on-site surface soil. There is no MRL, RfD, or cancer slope factor for this compound. IDPH could not find any information on chronic health effects of low level exposure to this chemical using TOXNET (1992), an on-line computer data base.

    bis(2-Ethylhexyl)phthalate

This compound was a chemical of concern in on-site monitoring wells, off-site private sand and gravel wells, and on-site surface soil. It is readily absorbed after inhalation or ingestion, and some is also absorbed after dermal contact (ATSDR, April 1993f). After absorption, most of it is converted into monoethylhexyl phthalate and 2-ethylhexanol. These compounds go to the kidneys, liver, testes, and small amounts are stored in fats. Most of these chemicals are eliminated from the body within 24 hours (ATSDR, April 1993f).

 

There is little information on the effects of bis(2-ethylhexyl)phthalate in humans, and most of the information on this chemical comes from animal studies. Developmental effects in animals include cardiological, neurological, and skeletal malformations in developing fetuses, as well as increased fetal deaths and resorptions. Other effects in animals include decreased fertility, kidney changes, lower birthweights, and liver cancer. It is unknown whether any of these effects may occur in humans (ATSDR, April 1993f). There is no MRL, RfD, or cancer slope factor available for this compound, so the possible risks of on- or off-site exposure cannot be evaluated.

    2-Butanone

2-Butanone was a contaminant of concern in only on-site shallow groundwater. It can be absorbed after inhalation, ingestion, or dermal contact (Sittig, 1985). There is no MRL, RfD, or cancer slope factor for this compound. It can cause irritation of the eyes and nose, dizziness, headaches, and vomiting (Sittig, 1985); however, these symptoms may or may not occur at the concentrations found on-site.

    Chloroethane

Chloroethane was found in on-site monitoring and private wells, as well as in subsurface soil. It can be absorbed after inhalation, ingestion, or dermal contact (ATSDR, August 1990b). There is no MRL, RfD, or cancer slope factor for this compound. While high doses can cause cancer in animals, it is unknown whether low doses of chloroethane can cause it. It is also unknown whether it can cause cancer in humans. There is little information on the effects of long-term exposure to chloroethane. Only one study was performed, and no health effects were observed in rabbits given higher doses than found on-site. However, the organs examined were not listed in the article (ATSDR, August 1990b).

    Chloromethane

Chloromethane was a contaminant of concern in only on-site bedrock monitoring wells. It can readily enter the body after ingestion and inhalation, and it can also be absorbed after dermal contact. There is no MRL, RfD, or cancer slope factor for this compound. There are no animal or human studies of health effects following chronic low dose exposure to chloromethane (ATSDR, June 1991a).

    Dibenzofuran

Dibenzofuran was found in on-site shallow groundwater and surface soil. There is no MRL, RfD, or cancer slope factor for this compound. IDPH could not find any information on noncarcinogenic effects of dibenzofuran using TOXNET (1992). There have been no animal or human studies of the possible carcinogenicity of dibenzofuran, and it has not caused mutations in experiments with bacteria (TOXNET, 1992).

    1,4-Dichlorobenzene

1,4-Dichlorobenzene was a contaminant of concern in only on-site surface soil. It can be absorbed after ingestion or inhalation, but it is unknown whether it can be absorbed after dermal contact (ATSDR, April 1993e). There is no MRL, RfD, or cancer slope factor for this compound, so the risks of on-site exposure cannot be fully evaluated. Noncancerous health effects in animals and humans (ATSDR, April 1991h) have been observed at much higher doses than those found on-site. After oral administration of 1,4-dichlorobenzene, liver cancer has been observed in male, but not female rats. In addition, kidney cancer has been observed in mice. It is unknown whether 1,4-dichlorobenzene can cause cancer in humans (ATSDR, April 1993e).

    1,1-Dichloroethane

1,1-Dichloroethane was found in on-site monitoring and private wells, as well as in subsurface soil. It can be absorbed after inhalation or ingestion, and probably also after dermal contact (ATSDR, June 1991b). There is little toxicological information on chronic, low-level exposure to this compound, and there is no MRL, RfD, or cancer slope factor for it. One study suggested 1,1-dichloroethane may cause cancer in animals, while another experiment came up with the opposite conclusion (ATSDR, June 1991b). Consequently, it is uncertain whether it may cause cancer.

    1,2-Dichloroethane

1,2-Dichloroethane was a contaminant of concern in only on-site private bedrock wells. It can enter the body after ingestion, inhalation, or dermal contact (ATSDR, May 1994a). Consumption of on-site water would not exceed the MRL, so noncancerous health effects are not expected. In one study, people exposed to 1,2-dichloroethane in drinking water exhibited increased rates of colon and rectal cancer; however, other chemicals were likely present and may have contributed to the observed effects. In rats and mice, oral exposure to this compound can cause cancer of the adrenal gland, liver, pancreas, skin, and spleen. Consequently, it may be able to cause cancer in people (ATSDR, May 1994a). Using the USEPA cancer slope factor, the estimated lifetime cancer risk of drinking the highest concentration found on-site, 2 ppb, is less than that of drinking from a chlorinated public water supply. Consequently, drinking on-site water should not result in an unacceptable cancer risk.

    1,2-Dichloroethene

This compound (isomer unknown) was at chemical of concern in only on-site shallow and intermediate monitoring wells. It can be absorbed after ingestion, inhalation, or dermal contact (ATSDR, August 1994). Ingestion of the highest on-site concentration would not exceed the MRL, so noncancerous effects are unlikely. The effects of long-term exposure to 1,2-dichloroethene are unknown (ATSDR, August 1994).

    Diethyl phthalate

This compound was found in only on-site subsurface soil. There is no MRL, RfD, or cancer slope factor for diethyl phthalate. In rats, it can cause birth defects, fetal toxicity, and fetal resorptions. It can cause mutations in bacteria, but there is no evidence it can cause cancer (Sittig, 1985).

    Beta-Hexachlorocyclohexane (or benzene hexachloride)

This compound was a chemical of concern in only on-site soil borings. Ingestion of this soil by a pica child would not exceed the intermediate MRL, so noncancerous health effects are not expected. In rats and mice, it is a liver carcinogen; however, it is unknown whether it can cause cancer in people (ATSDR, May 1994b). Using the USEPA cancer slope factor, the ingestion of on-site soil would result in an estimated lifetime cancer risk much less than the risk of drinking from a chlorinated public water supply. Consequently, ingestion of beta-hexachlorocyclohexane in on-site soil should not result in an unacceptable cancer risk.

    2-Hexanone

2-Hexanone was found in only on-site shallow groundwater. No MRL, RfD, or cancer slope factor is available for this compound. It can be absorbed after inhalation, ingestion, or dermal contact (ATSDR, March 1993c).

There is little information on the health effects of exposure to low concentrations of this chemical. The observed health effects (ATSDR, March 1993c) occurred at much higher concentrations than were found in on-site shallow groundwater.

    2-Methylnaphthalene

2-Methylnaphthalene was found in on-site shallow groundwater, as well as in surface and subsurface soil. It can be absorbed after inhalation, ingestion, or dermal contact (ATSDR, October 1993b). There is no MRL, RfD, or cancer slope factor for this compound. There have been no studies of health effects of 2-methylnaphthalene administered alone in animals or humans. In one mouse study, a mixture containing 2-methylnaphthalene, naphthalene, and ten other methylated and ethylated naphthalenes appeared to inhibit the development of benzo(a)pyrene-induced skin tumors (ATSDR, October 1993b).

    4-Methyl-2-pentanone (= methyl isobutyl ketone)

This compound was found in on-site subsurface soil. It can be absorbed after inhalation, ingestion, or dermal contact (Sittig, 1985). There is no MRL, RfD, or cancer slope factor for this chemical. Health effects of 4-methyl-2-pentanone include eye and mucous membrane irritation, dermatitis, and headaches dermatitis (Sittig, 1985); however, it is not known whether any of these symptoms may occur at concentrations found on-site.

    4-Methylphenol (= p-cresol)

4-Methyl phenol was found in on-site shallow groundwater, on- and off-site surface water, and on-site surface and subsurface soil. Ingestion of water with the highest concentration found in shallow groundwater would not exceed the acute or chronic MRL. Ingestion of soil with the highest level of 4-methylphenol found in on-site soil would not exceed the acute or chronic MRL (pica child). Consequently, no noncancerous health effects are expected from exposure to this compound.

    Naphthalene

Naphthalene was a contaminant of concern in only on-site shallow monitoring wells. It can be absorbed after ingestion, inhalation, or dermal contact. After absorption, it is eliminated in the urine over the course of several days (ATSDR, October 1993b). There is no MRL, RfD, or cancer slope factor for this compound. No symptoms have been reported in animals or people exposed to naphthalene at concentrations observed on-site (ATSDR, October 1993b).

    N-Nitrosodi-N-propylamine

This compound was a chemical of concern in on-site surface soil. No information could be found on absorption via different routes of exposure (ATSDR, August 1990c). Ingestion of the maximum concentration found in on-site soil by a pica child would not exceed the acute MRL, so noncancerous health effects are not expected from on-site exposure to this compound. Long-term oral exposure to N-nitrosodi-N-propylamine can cause cancer of the esophagus, liver, and nasal cavities in animals, but there have been no studies of people (ATSDR, August 1990c). Using the USEPA cancer slope factor, the estimated lifetime cancer risk from eating on-site soil is extremely low and not an unacceptable risk. There is no information of health effects in animals or humans after inhalation exposure (ATSDR, August 1990c).

    N-Nitrosodiphenylamine

N-Nitrosodiphenylamine was a contaminant of concern in only background soil borings. Very little is known about the health effects of this chemical in animals (ATSDR, April 1993h). Ingestion of background soil by a pica child would not exceed the chronic MRL, so noncancerous health effects are not expected from exposure to this compound. Long-term (chronic) oral exposure in animals caused bladder cancer. It can also cause genotoxic effects (gene damage) in some cell cultures. It is unknown whether it can cause cancer in people (ATSDR, April 1993h). Using the USEPA cancer slope factor, the estimated lifetime cancer risk of ingesting soil with the maximum detected concentration of this compound is extremely small and would not pose an unacceptable risk.

    Pentachlorophenol

Pentachlorophenol was a chemical of concern in only on-site shallow monitoring wells. It is readily absorbed after inhalation or dermal contact, and it is also absorbed after ingestion. Studies show that after absorption, half of the chemical is eliminated from the body in 33 hours, so it does not accumulate (ATSDR, May 1994c). Ingestion of water with the maximum on-site concentration would not exceed the intermediate MRL, so noncancer health effects are not expected from exposure to pentachlorophenol. In mice and rats, oral exposure to pentachlorophenol has been associated with cancer of the adrenal gland, liver, and spleen (mice only). However, this compound is often contaminated with polychlorinated dioxins, which can cause liver cancer in mice, but not the other cancers (ATSDR, May 1994c). It is not known whether polychlorinated dioxins are present on-site. Based on the animal studies, USEPA has developed a cancer slope factor, which can be used to estimate cancer risks from lifetime exposure. Using this slope factor, lifetime consumption of water with the highest concentration on-site, 9 ppb, would give an estimated risk less than that of drinking from a chlorinated public water supply. Consequently, the on-site levels of pentachlorophenol do not pose an unacceptable cancer risk. Furthermore, as previously discussed, these slope factors are extremely conservative and may overestimate the actual risk.

    Polycyclic Aromatic Hydrocarbons

Many of the contaminants found on- and off-site are polycyclic aromatic hydrocarbons (PAHs), including acenaphthene, benz(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(g,h,i)perylene, benzo(a)pyrene, chrysene, dibenz(a,h)anthracene, indeno(1,2,3-c,d)pyrene, and phenanthrene. For all but benz(a)anthracene, comparison values were not available for the medium of detection. Benz(a)anthracene was a contaminant of concern in on-site surface and subsurface soil, as well as in the sediments of on-site depressions.

PAHs can be absorbed after inhalation or ingestion, but dermal absorption would occur at only much higher concentrations than found on-site (ATSDR, October 1993a). No MRLs, RfDs, or cancer slope factors are available for these chemicals. Many of the PAHs are suspected carcinogens. Benz(a) anthracene has been shown to cause skin cancer in mice, and there is evidence that it may also cause cancer after oral administration (ATSDR, October 1993a). In animals, benzo(a)pyrene can cause many types of tumors, including lung (inhalation exposure), skin (dermal exposure), and mammary cancer (ingestion exposure; ATSDR, October 1993a). Chrysene can cause cancer in animals after dermal administration, but health effects after other routes of exposure have not yet been investigated (ATSDR, October 1993a). Mixtures of PAHs, such as coal tar, can also cause cancer in animals (ATSDR, October 1993a). Anthracene, fluoranthene, and pyrene cannot cause cancer in animals when administered alone (ATSDR, October 1993a). The available toxicological information, however, is insufficient to develop cancer risk estimates for given exposures. Consequently, the possible cancer risks from exposure to on- and off-site PAHs cannot be evaluated.

PAHs can also have other health effects on animals. After oral intake, benzo(a)pyrene can cause decreased fertility, increased sterility in pregnancy, and significantly different pup weight, as well as increased stillbirths, resorptions, and malformations in mice. It is not known whether or not these effects may occur in humans (ATSDR, October 1993a).

    PCBs

PCBs were chemicals of concern in sediments of on-site depressions and soil of Elgin Landfill test pits. PCBs can be absorbed after ingestion or inhalation, and some uptake can occur after dermal contact. It will accumulate in organisms, primarily in fat (ATSDR, April 1993i). Eating soil with the maximum concentrations of PCBs found in the test pits or sediments of on-site depressions would exceed the chronic MRL for pica children, non-pica children, or adults. Young children of women who ate food containing certain concentrations of PCBs before and during pregnancy may have some trouble learning. Animals given PCBs in food for several weeks or months exhibited liver, stomach, and thyroid gland damage, as well as anemia, acne, and damaged reproduction. Mice and rats given PCBs in food exhibited liver cancer, and some other cancers (stomach, intestine) may also be elevated. However, commercial PCB mixtures are generally contaminated with polychlorinated dibenzofurans, which may be at least partially responsible for the observed health effects of PCBs (ATSDR, April 1993i). It is not known whether polychlorinated dioxins are present on-site. Using the USEPA slope factor, the estimated lifetime cancer risk of lifetime ingestion of soil with the maximum on-site concentration of PCBs is less than that of drinking from a chlorinated public water supply. Consequently, on-site PCBs should not pose an unacceptable cancer risk. Absorption of PCBs from the types of sediments and soils found on-site, as well as the frequency of exposure, are unknown; consequently, it is difficult to establish whether any of these health effects are possible from on-site exposure.

    Tetrachloroethene

Tetrachloroethene was a chemical of concern in only on-site shallow monitoring wells. It can be absorbed after ingestion or inhalation (ATSDR, April 1993j). In humans, the health effects from drinking water with low levels of tetrachloroethene are essentially unknown. In one study, people served by a water supply contaminated with organic solvents, including 21 ppb of tetrachloroethene and 267 ppb of trichloroethene (at the wells) exhibited increased respiratory disorders (asthma, bronchitis, pneumonia in children), as well as constipation, decreased blink reflex, diarrhea, immunologic abnormalities, leukemia, nausea, and skin lesions. However, because of uncertainties in the actual levels of exposure at the tap, the length of exposure, and exposure to other chemicals, it is uncertain whether tetrachloroethene caused any of these effects (ATSDR, April 1993j). Drinking water with maximum on-site concentration of tetrachloroethene would not exceed the chronic RfD; consequently, exposure to this chemical should not cause any noncancerous health effects. In animals, it can cause kidney and liver cancer, but these cancers have not been reported in people exposed to tetrachloroethene (ATSDR, April 1993j). The estimated cancer risk from drinking water with the highest concentration of this compound, 13 ppb, would be less than that from consuming water from a chlorinated public water supply. Consequently, drinking on-site water should not result in an unacceptable cancer risk. Furthermore, as previously discussed, these risk estimates are conservative and may overestimate the actual risk.

    1,2,4-Trichlorobenzene

This compound was found in only on-site surface soil. Ingestion of soil with the maximum on-site concentration found on-site by a pica child would not exceed the RfD; consequently, non-cancerous health effects are not expected from exposure to this chemical.

    1,1,1-Trichloroethane

1,1,1-Trichloroethane (1,1,1-TCA) was found in background and on-site intermediate monitoring wells, as well as in on-site subsurface soil. It can be absorbed after inhalation or ingestion, and some can also enter the body after dermal contact. Once absorbed, it is rapidly eliminated from the body through the lungs (ATSDR, October 1993c). There is no MRL, RfD, or cancer slope factor for this compound. The possible health effects of long-term, low level exposure to 1,1,1-TCA are unknown (ATSDR, October 1993c).

    Trichloroethene

Trichloroethene was a contaminant of concern in only on-site shallow monitoring wells. It can be absorbed after inhalation or ingestion, but skin absorption is unlikely at the concentrations present on-site. In one study, people served by a water supply contaminated with organic solvents, including 267 ppb of trichloroethene and 21 ppb of tetrachloroethene (at the wells) exhibited increased respiratory disorders (asthma, bronchitis, pneumonia in children), as well as constipation, decreased blink reflex, diarrhea, immunologic abnormalities, leukemia, nausea, and skin lesions. However, because of uncertainties in the actual levels of exposure at the tap, the length of exposure, and the exposure to other chemicals, it is uncertain whether trichloroethene caused any of these effects (ATSDR, April 1993k). Consumption of on-site ground water would result in a dose less than the MRL, so noncancerous health effects are not expected from this compound. In animals, trichloroethene can cause liver cancer, but this effect has not been reported in humans (ATSDR, April 1993k). The estimated cancer risk of drinking groundwater with the maximum concentration of this compound, 24 ppb, is less than that of drinking from a chlorinated public water supply. Consequently, drinking on-site water should not result in an unacceptable cancer risk. Furthermore, as previously discussed, these risk estimates are conservative and may overestimate the actual risk.

    2,4,5-Trichlorophenol

This compound was found in only on-site surface soil. Ingestion of soil with the maximum on-site concentration by a pica child would not exceed the RfD, so noncancerous health effects are not expected from exposure to this compound.

    Vinyl Chloride

Vinyl chloride was a chemical of concern in on-site shallow and intermediate monitoring wells. It can enter the body after inhalation or ingestion. After absorption, most of it is eliminated from the body within one day. However, some is converted into other chemicals, which are often more toxic and are eliminated more slowly (ATSDR, April 1993L). Consumption of water with the maximum concentration of vinyl chloride would exceed the chronic MRL for adults and children, so noncancerous health effects may occur. In animals, chronic oral exposure to vinyl chloride can cause liver damage and liver cancer. Consequently, it may be able to cause cancer in people after oral exposure (ATSDR, April 1993L). The available data are insufficient to estimate the possible cancer risk of vinyl chloride on-site.

    2.    Inorganic Chemicals
      Antimony

Antimony was a contaminant of concern in on-site and background monitoring and private wells, as well as in on-site sediments, surface soil, and subsurface soil. It can enter the body after ingestion or inhalation (ATSDR, March 1993a). Ingestion of water with the maximum on-site concentration would exceed the RfD for adults and children, so noncancerous health effects may occur from antimony exposure. Consumption of soil with the maximum on-site concentration by a pica child would not exceed the RfD, so exposure to antimony in soil should not cause any noncancerous health effects. Chronic antimony exposure in air can irritate the eyes, lungs, and skin, and it can also cause diarrhea, heart problems, and vomiting (ATSDR, March 1993a). However, these symptoms occurred at higher concentrations than expected on-site. Animals have contracted lung cancer after breathing antimony dust, and the cancer risk may depend on particle size. However, airborne concentrations of antimony are unknown, so cancer risks cannot be evaluated. There are no animal or human studies of chronic ingestion exposure to antimony (ATSDR, March 1993a).

    Arsenic

Arsenic was a chemical of concern in on-site and background monitoring wells, on- and off-site private wells, background and on-site surface and subsurface soil, and background, on-site, and background sediments. Arsenic can be absorbed after inhalation or ingestion. Inhalation of arsenic increases the risk of lung cancer (ATSDR, April 1993a). However, airborne concentrations are unknown, so this risk cannot be examined. Oral exposure to arsenic has been linked to increased incidence of skin cancer in people (ATSDR, April 1993a). For ingestion, the available data are insufficient to estimate the cancer risks of specific doses. The ingestion of on-site groundwater by children would result in an intake greater than the RfD. Consumption of surface or subsurface soil with the highest arsenic concentration by a pica child would exceed the RfD, but incidental ingestion by an adult would not. This RfD is based on studies that showed ingestion of arsenic can cause areas of skin pigmentation. This RfD is currently being reviewed by USEPA (ATSDR, April 1993a). In the body, arsenic is converted into methyl arsenic or dimethyl arsenic by enzymes, and these latter compounds are less toxic and more easily excreted. It is uncertain what intake of arsenic can be detoxified by this process, but limited data indicate the enzymes may begin to be saturated (i.e., cannot convert at a faster rate) at doses of 0.003 to 0.015 milligrams per kilogram per day. Consequently, doses below 0.001 milligrams per kilogram per day are likely to pose little risk of noncancer health effects (ATSDR, April 1993a). Using the maximum arsenic level found in a private well, 28.4 ppb, the intakes of an adult or a child drinking the water would be 0.0008 milligrams per kilogram per day and 0.0028 milligrams per kilograms per day, respectively. Consequently, drinking water from the private well with the highest arsenic concentration should not result in any noncancer health effects in adults. While it is possible effects could occur in children, it is unlikely they would be drinking the water of a business on a regular basis.

    Barium

Barium was a chemical of concern in on-site groundwater, soil, and sediment, as well as in off-site surface water. Ingestion of on-site groundwater by children would result in a dose over the USEPA RfD. Health effects seen in people exposed to barium include difficulty breathing, increased blood pressure, changes in heart rhythm, stomach irritation, minor changes in blood, muscle weakness, changes in nerve reflexes, swelling of the brain, and damage to the liver, kidney, heart, and spleen (ATSDR, March 1993b).

    Beryllium

Beryllium was a chemical of concern in on-site groundwater and off-site private sand and gravel wells, as well as in on- and off-site soil and sediment. Beryllium can be absorbed after inhalation, but absorption after ingestion is negligible. Inhaled beryllium can cause lung damage, and some people can develop allergies to airborne beryllium (ATSDR, April 1993b). Airborne concentrations of beryllium are unknown, so these risks cannot be evaluated. No health effects have been reported in humans after ingestion exposure (ATSDR, April 1993b). Drinking on-site groundwater with the highest detected level of beryllium, 0.7 ppb, would not result in an intake above the RfD. The consumption of surface soil with the highest concentration of beryllium by a pica child would also not exceed the RfD.

    Cadmium

Cadmium was a chemical of concern in on-site monitoring wells, on-site surface and subsurface soil, on-site sediments, and sediments of the background marsh. Cadmium is readily absorbed after inhalation or ingestion, but little enters the body after dermal contact. Once absorbed, it accumulates in the body, particularly in the kidney and liver. It can also bioaccumulate in fish, livestock, and plants. Ingestion of on-site shallow groundwater with the maximum detected concentration of cadmium would exceed the chronic MRL for children and adults. Ingestion of surface or subsurface soil with the maximum cadmium concentration by a pica child would also exceed the chronic MRL. Chronic exposure to low levels of cadmium can result in enough accumulation to cause toxic effects, including kidney damage, and possibly also anemia, endocrine alterations, high blood pressure, immunosuppression, and loss of smell. Cadmium exposure in pregnant women may result in lower birth weights, but birth defects have not been observed in humans (ATSDR, April 1993c).

    Chromium

Chromium was a contaminant of concern in on-site monitoring and private wells, as well as in on-site soil and on-and off-site sediments (including background). Chromium can be absorbed after inhalation or ingestion. It occurs in several oxidative states, and only the hexavalent one has been associated with toxic effects. It is unknown whether any of the detected chromium was in this oxidation state; consequently, it is uncertain whether chromium poses any health risk to humans on- or off-site. After inhalation, hexavalent chromium can cause lung cancer, but there is no evidence it can cause cancer after ingestion or dermal exposure (ATSDR, April 1993d). Airborne concentrations of hexavalent chromium are unknown, so the lung cancer risk on- and off-site cannot be evaluated. The highest concentration of chromium in groundwater was in an on-site private well, which serves a business. Consequently, the exposure of adults is more likely than children. In the past, a person lived at an on-site business in an attached apartment (Seely, 1992), so the exposure of children is possible. Drinking water from the well with the highest chromium concentration would exceed the RfD for both children and adults if the element is in the hexavalent state, which is unknown. The consumption of surface or subsurface soil by a pica child would also exceed the RfD if the element is in the hexavalent state. While respiratory, cardiovascular, gastrointestinal, blood, liver, kidney, and skin effects, as well as decreased weight gain (pregnant mice) have been seen in people or animals that ingested chromium (ATSDR, April 1993d), these effects occurred at higher doses than are likely on-site.

    Fluoride

Fluoride was a chemical of concern in only deep monitoring wells. Consumption of this water by children would exceed the USEPA RfD. At low concentrations, fluoride is beneficial, however, higher levels may have harmful effects. Some children who drink water with more than 4 ppm of fluoride subsequently may have staining or mottling of new permanent teeth. These teeth tend to be more fragile and are at increased risk of cavities. Skeletal fluorosis can be caused by long-term ingestion of large amounts of fluoride, which makes bones brittle (Klaassen, 1986; Menzer and Nelson, 1986; Sittig, 1985). While the exact level of exposure which can cause this condition is not well-defined (Menzer and Nelson, 1986), the concentration of fluoride in the deep monitoring wells are within the suspected range. Fluoride is not know to cause birth defects, affect reproduction in people or animals, or cause cancer in people.

    Lead

Lead was elevated in on-site monitoring wells and some off-site private wells, as well as in water from the on-site drainage ditch and subsurface soil. Lead can be absorbed after inhalation or ingestion. After inhalation, nearly all of the lead deposited in the lower respiratory tract is absorbed, regardless of the chemical form. After ingestion, absorption in children is about 50%, while only 8 to 15% of ingested lead is absorbed by adults. In adults, the absorption of lead after fasting can be up to 45%. Lead uptake is higher in people with inadequate calcium, iron, selenium, and zinc intakes, and it is also increased by fatty foods. In children, about 30% of the ingested lead in soil is absorbed. In the body, lead is mostly deposited in bone, with a half-life of 27 years. The half-life of a chemical in the body is the time for half of it to be eliminated. In adults, 95% of the lead body burden is in bone, while about 73% of it is in the bone of children. Lead in bones is liberated during pregnancy and lactation. It can readily pass the placenta, and because of its persistence in bone, fetal uptake can occur long after maternal exposure has ended (ATSDR, April 1993g). In one case, a lead-poisoned child was born to a mother who herself had been lead-poisoned at the age of two, over 30 years before. No other significant source of lead exposure could be established (Silbergeld, 1991). Infants and children up to 2 years old retain 34% of the absorbed lead, while adults retain only 1% of it (ATSDR, April 1993g).

The most serious effect of lead is neurological impairment, and children are the most susceptible. In children, prenatal exposure, as well as postnatal blood lead levels of 10 to 15 micrograms per deciliter, have been associated with numerous disabilities, including cognitive deficit (decreased IQ), decreased growth, reduced birth weight, and reduced hearing. There seems to be no threshold below which lead does not affect IQ or hearing (ATSDR, April 1993g), and the neurological effects of lead seem to be permanent (Needleman et al., 1990).

In children, lead can cause kidney damage at blood lead levels of 30 micrograms per deciliter, as well as vitamin D deficiency and symptoms of rickets above about 33 micrograms per deciliter (ATSDR, April 1993g). However, it is questionable whether this could occur from exposure to lead levels found in on-site soil.

Because of their greater uptake, slower elimination, and greater sensitivity to lead, children 6 years old or less are the most susceptible. Because of frequent hand-to-mouth activity, 18 months to 2.5 years of age is the most critical time.

Given their lower absorption of and decreased sensitivity to lead, it is unlikely that adults would absorb enough lead from on-site soil or groundwater to cause observable symptoms. However, lead absorbed by pregnant females or women who may be pregnant in the future could be transferred to fetuses in cord blood and infants in breast milk, potentially causing health problems in the children.

Lead concentrations in wells 6 (probably not site-related) and 7 (may be site-related), as well as in on-site monitoring wells are high enough that the water in them should not be consumed by children, pregnant women, or women who may become pregnant in the future.

USEPA has established an action level of 15 ppb for public drinking water supplies. ATSDR has not established a MRL for lead.

    Manganese

Manganese was a contaminant of concern in monitoring wells, on- and off-site soil, and on-site and background sediments. Manganese can be absorbed after ingestion or inhalation. Only about three to five percent of ingested manganese is absorbed, but the amount absorbed after inhalation is unknown. Consumption of on-site shallow groundwater with the highest manganese concentration, 12 ppm, by adults or children would exceed the RfD. There is controversial evidence that elevated manganese levels similar to those found on-site may be able to cause brain damage, with symptoms such as weakness, stiff muscles, and trembling of the hands. However, other chemicals may have been involved, and it is uncertain whether manganese was the cause (ATSDR, March 1993d).

    Mercury

Mercury was a chemical of concern in only shallow monitoring wells. It can enter the body after inhalation, ingestion, or dermal contact. Long-term exposure to inorganic or organic mercury can cause permanent damage to the brain, kidneys, or developing fetus. Low-level exposure to mercury vapors can cause damage to the kidneys and nervous system. Nervous system effects include tremors which initially affect the hands, as well as decreases in motor function, excessive shyness, and insomnia (ATSDR, May 1994d). If shallow on-site groundwater with the maximum mercury concentration were consumed by children, it would not exceed the RfD for inorganic mercury, but it would exceed the RfD for organic mercury. It is unknown whether the on-site mercury is in an organic or inorganic form. Consequently, it is not known whether non-cancerous health effects may occur from mercury exposure.

    Nickel

Nickel was a chemical of concern in on-site monitoring and private wells, as well as in on-site surface and subsurface soil. This element can be absorbed after ingestion or inhalation, and a small amount can be absorbed after dermal contact. Most ingested nickel is not absorbed, but is eliminated in the feces. After absorption, most nickel is transported to the kidneys and is eliminated in the urine. There is no MRL, RfD, or cancer slope factor available for this chemical. Lung and nasal cancer have been observed after occupational exposure (ATSDR, April 1993m); however, these people were exposed to much higher levels than are likely on-site. In two mouse studies, nickel did not cause cancer after oral exposure, and there is no information about cancer in people after oral exposure. Oral and dermal exposure to levels of nickel similar to those on-site can cause allergy. Sensitized individuals then exhibit skin dermatitis after being dermally exposed to nickel (ATSDR, April 1993m).

    Nitrate + Nitrite

Nitrate + Nitrite were chemicals of concern in on-site shallow groundwater and an off-site background private well. The nitrate + nitrite in the private well may have come from a malfunctioning septic system. In the body, nitrates are converted into nitrites, which may cause two health effects, methemoglobinemia and possibly also cancer. In methemoglobinemia, nitrites decrease the ability of the blood to carry oxygen, which can result in anoxia and death. However, only infants are susceptible to this condition. The no adverse health effect limit for nitrate + nitrite is about 10 ppm, but there is a small safety factor in this estimate. Nitrite can also react with secondary amines to form N-nitroso compounds, many of which are carcinogens (Sittig, 1985).

    Selenium

Selenium was a contaminant of concern in on-site and background surface soil. For a pica child, ingestion of soil with the maximum detected selenium concentration would not exceed the intermediate MRL, so no noncancerous health effects are expected from exposure to this element. There is controversial evidence that low selenium intake may be associated with some types of cancer (Van't Veer et al., 1990; Hunter et al., 1990).

    Thallium

Thallium was a contaminant of concern in on-site monitoring wells and off-site private wells. It is readily absorbed after ingestion and can also be absorbed after inhalation or dermal contact. Once absorbed, it is mainly transported to the liver and kidneys. About half of the absorbed thallium is eliminated from the body in three days. There are no data on health effects in humans or animals following long-term exposure to low levels of thallium (ATSDR, March 1993e). The most sensitive effect observed in animals was that offspring of rats given 0.08 milligrams per kilogram per day exhibited lower learning ability (ATSDR, 1990f). While this effect has not been seen in humans, ATSDR used safety factors to account for uncertainties in extrapolating from animals to humans and calculated an acute MRL for thallium, 0.00008 milligrams per kilogram per day. If the shallow on-site groundwater were consumed, it would result in a dose of about 0.0007 milligrams per kilogram per day, assuming a female body weight of 40 kilograms or 110 pounds. Consequently, consumption of this water may pose an unacceptable health risk to humans. On the other hand, consuming the highest concentration found in a private well would result in a dose of about 0.00015 milligrams per kilogram per day, which should not pose any health risk. There have been no studies of learning ability in children following maternal thallium consumption during pregnancy (ATSDR, March 1993e).

    Vanadium

Vanadium was a chemical of concern in on-site shallow monitoring wells and surface water. Vanadium is poorly absorbed after ingestion, and some is absorbed after inhalation. Consumption of water with the highest on-site concentration would not exceed the intermediate MRL, so health effects in humans are not expected from vanadium.

B.    Health Outcome Data Evaluation

There was no site specific health outcome data identified that was appropriate to this site. At this time, there are no plans to perform an evaluation of health outcome data because exposure was limited to a small population. This small exposed population size would not provide any statistically significant data.

C.    Community Health Concerns Evaluation

  1. People of South Elgin are concerned about the possible future contamination of their water supply.

    Because the geology and hydrogeology northwest of the site are unknown, it is difficult to examine the likelihood of this occurrence. Shallow and possibly also intermediate groundwater in the northern part of the site moves to the north or northwest, but the direction of groundwater flow beyond the site boundary is unknown. In addition, the presence of any hydraulic connection between this contaminated water and that of the Newark Aquifer, the water source of South Elgin, is unknown. If shallow and intermediate groundwater continues moving in the same direction off-site and hydraulic connections between them and deeper aquifers exist, contamination could potentially reach the South Elgin municipal wells. Some contamination is present in the shallow dolomite aquifer, which is hydraulically connected to the Newark Aquifer. While the flow of groundwater off-site is unknown, before dewatering of the Woodland Landfills occurred, on-site, it was moving to the southwest. This would carry any contaminants away from the South Elgin municipal wells and toward those of Valley View. While the present groundwater flow is more toward South Elgin, any contaminants may be intercepted by dewatering wells at the Woodland Landfill. While the flow in the Newark Aquifer is thought to be to the southwest along it, this is not certain. Furthermore, well cones of depression can alter the flow. The population of the area is expanding rapidly, so it is likely city water supplies will be expanded in the future. This will require more groundwater withdrawal (and probably more municipal wells), which will create larger or additional cones of depression. This could alter the groundwater flow and result in the movement of site contaminants into the wells. However, it is not known whether any chemicals would reach wells at levels of health concern. Instead, they may be diluted by unaffected water in the aquifer. Consequently, it is not known whether future contamination of the South Elgin public water supply is likely.

  2. People are concerned leachate collection by the proposed alternative may affect the Woodland Landfill.

    The Woodland Landfill is a modern one which does not accept hazardous wastes. It has a clay cap, sidewall, and floor, as well as a leachate collection system, which should inhibit the movement of any contaminants out of it.

  3. People are concerned that in the proposed remedial alternative, there will be no collection trench on the southwestern part of the landfill.

    According to Seely (1992), Lance (1992), and WW Engineering and Science (1992), the other trenches will create cones of depression, which will prevent contaminants from moving to the southwestern corner of the site. Instead, groundwater will flow downgradient into the leachate collection system. The gray silty clay layer at that location will keep contaminants from moving downward and help divert them to the trenches. Minimizing the size of the trenches and leachate collection system will save money (Seely, 1992; Lance, 1992; WW Engineering and Science, 1992). This assumes the gray silty clay is continuous in this area, which may or may not be true. If it is not continuous, some contaminated groundwater may move down into deeper groundwater instead of being intercepted by the trenches. The presence of contaminants in deeper groundwater indicate the gray silty clay is not a sufficient barrier to prevent deeper groundwater contamination. While the area near BP33A, where the gray silty clay is thin to absent, may be a main connection between the shallow and intermediate aquifers, it may not be the only one.

  4. Concern has been expressed that in the proposed alternative, there will be no trench along Route 25 east of the site to intercept incoming groundwater.

    According to Seely (1992) the goal of the proposed leachate collection system is to remove contaminated water and not to prevent contact of clean water with the wastes. Again, this method relies on the impermeability of the gray clay to prevent contamination of deeper groundwater. This has been previously discussed.

  5. Some people are concerned leachate collection by the proposed alternative may de-water nearby private wells.

    According to Seely (1992) and WW Engineering and Science (1992), leachate collection would extract only shallow groundwater, and the surrounding private wells use deeper water, which would not be affected. While removing a large amount of water from the shallow groundwater may reduce recharge, the total amount of water removed by the leachate collection system will probably be too small to affect private wells.

  6. People are concerned the gray silty clay under the site may not prevent the future contamination of their private wells, even with the proposed leachate collection system.

    This concern has already been addressed.

  7. Another concern is that the Woodland Landfill may cause groundwater contamination.

    This landfill is a modern one with a clay cap, side walls, and bottom, as well as a leachate collection system. It is not likely to cause groundwater contamination, at least at this time.

  8. Concerns have been expressed about the future care and maintenance of the leachate collection system, as well as monitoring groundwater.

    According to Seely (1992), quarterly groundwater monitoring, along with general cap and flare maintenance, will be required for 30 years as part of the remedy. Either Superfund or the responsible parties will perform the monitoring and maintenance Seely, 1992.

  9. People are concerned whether a berm would be constructed around the site.

    According to Seely (1992), one is not planned at this time.

  10. Another citizen concern is continued waste acceptance by the Elgin Landfill.

    According to Seely (1992), USEPA does not believe the landfill has accepted waste since 1990, and once the remedial plan is put into action, the Elgin Landfill will not be allowed to accept more waste.

  11. Another concern is that few surface soil samples were taken from the western side of the landfill.

    According to Seely (1992) and WW Engineering and Science (1992), surface soil sampling was focused in areas where leachate from the landfill had stained the soil or the cap was thin. On the western side of the Tri-County Landfill, the cap is thicker, shows no signs of leachate stains, and USEPA presumed the cap material was originally clean (Seely, 1992; WW Engineering and Science, 1992). Because of the proximity of the Prairie Path, however, the western side of the site is the most likely one to be contacted by the public. Consequently, surface soil in this area should be sampled to verify it is not contaminated.

  12. People are concerned about the future contamination of private wells.

    While the geology around the site is poorly understood, if contaminated groundwater continues moving in the same direction off-site, a number of additional private wells may become contaminated. This was discussed in the Pathways Analysis section of this document.

  13. People are concerned that according to the risk assessment (WW Engineering and Science, 1991b), the risk of cancer from breathing arsenic in dust is 2/10. They wanted to know if that meant 2/10 of them would get cancer.

    According to Seely (1992), this was a typographical error, and it should have been 2/10,000. After learning this at the August 4, 1992 public meeting, people insisted USEPA make a media announcement to ease the fear the original report raised. The 2/10,000 risk estimate was based on modeling results. The results of models greatly depend on the assumptions used in them. ATSDR does not consider them a substitute for actual sampling, and the modeling results were not used in this report.

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