PUBLIC HEALTH ASSESSMENT
ROCKFORD, WINNEBAGO COUNTY, ILLINOIS
The tables in this section list the contaminants of concern that are associated with the WRL site. These contaminants will be further evaluated in the remaining sections of this health assessment to determine if they pose a threat to public health. The listing of a contaminant in the following tables does not necessarily mean that the contaminant poses a threat to public health. The selection of these contaminants is based on the following factors:
- Concentrations of contaminants on and off the site.
- Data quality, both in the field and in the laboratory, and the sampling plan design.
- Comparison of contaminant concentrations and background concentrations with health assessment comparison values for both carcinogenic and noncarcinogenic endpoints (discussed further below).
- Community health concerns
Comparison values for health assessment are media-specific chemical concentrations 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 Guides (RMEGs), Lifetime Health Advisories (LTHAs), and Maximum Contaminant Levels (MCLs). If a site-related contaminant is discovered at levels above any of these comparison values it will be investigated further in the remaining sections of the health assessment to determine if it poses a significant threat to public health.
EMEGs are comparison values developed for chemicals that are potentially hazardous, frequently encountered at NPL sites, and present a potential for human exposure. They are derived to protect the most sensitive members of the population (e.g., children) and are not cut-off levels, but rather comparison values. They do not consider carcinogenic effects, chemical interactions, multiple routes of exposure, or other media-specific routes of exposure, and are very conservative concentration values.
CREGs are estimated contaminant concentrations based on one excess cancer in a million persons exposed to a chemical over a lifetime. These are also very conservative values designed to protect sensitive members of the population.
RMEGs are comparison values based on USEPA reference values which are estimates of a daily oral exposure to a certain chemical that is not likely to produce any noncarcinogenic adverse health effects over a lifetime. These values have been adjusted to protect sensitive members of the population.
LTHAs are concentrations an individual can be exposed to through drinking contaminated water 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 only considered if no EMEG, CREG, or RMEG is available for the chemical.
MCLs have been established by USEPA for public water supplies to reduce the chances of adverse health effects from contaminated drinking water. These standards reflect the best achievable levels considering the occurrence, relative source contribution factors, monitoring capabilities, cost of treatment, available technology, and health effects. These are enforceable limits that public water supplies must meet. These values are only considered if no EMEG, CREG, RMEG, or LTHA is available for the chemical. Proposed Maximum Contaminant Levels (PMCL) are also sometimes used in the absence of MCLs. These are proposed standards under consideration by the USEPA.
Compounds for which none of the above health comparison values exist will be considered as contaminants of concern and will be assessed in the remainder of the health assessment. Known or suspected human carcinogens will also be included if no cancer comparison value exists.
During the RI for this site, areas on and around both Acme and WRL were studied. Sampling was conducted in two phases and consisted of the installation and subsequent sampling of several new monitoring wells, groundwater sampling of the shallow aquifer, leachate sampling from the landfill, sampling of surface water and sediments from nearby Killbuck Creek, and air samples from the landfill. The purpose of Phase I activities was to define the nature and extent of potential releases of leachate to the groundwater around the site (12). Phase I activities included collection of four rounds of leachate samples from various areas of the facility, installation of 15 new groundwater monitoring wells adjacent to and downgradient form the site, collection of two rounds of groundwater samples from various wells around the site, collection of one round of surface water and sediment samples, and collection of ambient air samples. At the completion of Phase I activities, the Interim Groundwater Quality Evaluation (IGQE) was prepared and submitted to USEPA. Phase II sampling was based on recommendations in the IGQE and included collection of two more rounds of groundwater samples from some existing wells, another round of surface water samples, and another round of leachate samples. The boundaries of this site have not been well defined and on- and off-site groundwater samples were not delineated in the RI. Groundwater evaluation in this health assessment, therefore, has been presented in the On-Site Contamination section and includes both on- and off-site groundwater analysis.
The first two rounds of groundwater samples were taken during Phase I operations in April and June of 1988. Rounds 3 and 4 were taken during Phase II operations in February and April 1990. Round 1 and 2 samples were collected from wells on or around the Acme Solvents site (Figure 5). Round 3 and 4 samples focused on wells that were around the perimeter of the landfill or downgradient (west) of the site. Results were generally consistent between all four rounds indicating the greatest contamination in monitoring wells near the Acme Solvents site and just west of Lindenwood Road. Both of these areas are upgradient of the WRL and the source of this contamination is unknown. The Acme Solvents site is a potential source of this contamination. Samples taken from wells downgradient of the landfill also indicate some migration of contaminants northwest of the landfill. It has been suggested that the plume from WRL has overlapped a pre-existing plume from Acme Solvents based on specific indicator contaminants (12). It is difficult, therefore, to definitively distinguish which contaminants have migrated from the WRL site and which have come from the Acme Solvent site or other area sources.
Chlorinated hydrocarbons are the main contaminants of concern in groundwater around this site (Tables 2 and 3). The greatest concentrations were detected upgradient of the landfill; however, several of these compounds were detected above levels of health concern in downgradient wells. Several other organic compounds were also detected in area groundwater. Only one, benzene, was detected above levels of health concern.
Several metals were detected in wells throughout the area, particularly around the perimeter of the landfill. Five metals were detected above levels of public health concern in area groundwater (Table 2). One private well downgradient of the site was also sampled during rounds 1 and 2. This well displayed no site-related contamination.
An attempt to determine the origin of contamination was made through the use of inorganic compounds associated with the landfilling operations; however, this information is conjectural and does not definitively identify the origin of the contamination. In particular, the chloride ion (Cl-) was chosen as an indicator of contamination from the WRL since this compound was detected in WRL leachate and was not detected in significant quantities upgradient of the site. Several upgradient wells were chosen to provide background chloride concentrations with values ranging from 3 milligrams per liter (mg/l) to 30 mg/l. Wells that displayed contamination above these background levels of chloride were assumed to have been contaminated with compounds from the WRL facility. If chloride was not detected in the wells above background levels, the contamination was assumed to be from a different source. Other potential sources of chloride contamination in groundwater include the use of residential water softeners, road salts, and dust suppressants.
Two general areas of elevated chloride contamination were discovered (Figures 6 to 9). These areas, the northwest quadrant of the WRL and well G110 (south-east border of the landfill) displayed elevated levels of chloride well above background levels in round 1 sampling. Round 2 sampling indicated a similar pattern with the addition of elevated concentrations in the deep well G116. This indicates that the plume from WRL has migrated west below Killbuck Creek. Well G116A, the shallow well west of Killbuck Creek, did not display elevated chloride levels indicating that the WRL plume has not affected the shallow aquifer in this area. Rounds 3 and 4 chloride sampling were consistent with rounds 1 and 2 indicating contamination in the northwest quadrant of the site and near the southeast border of the landfill. Recent information has indicated that leachate-hauling trucks were loaded near the contamination discovered at the southeast border and may be a possible contributing source of the contamination. Chloride concentrations also appeared to be elevated in well G115 at the southwest border of the landfill.
Four rounds of leachate samples were collected during Phase I of the RI from August 1988, to June 1989 and a fifth round was collected during Phase II in the spring of 1990. In each of the five rounds of sampling, two samples were collected from leachate extraction manholes which are connected to the base leachate collection piping system. The remaining four samples in each round were collected from various gas extraction wells located in the eastern portion of the WRL (12). Figure 4 shows the leachate sampling locations. The leachate composition characterizes the waste materials and the type of contaminants that could potentially reach the underlying soils and groundwater through faults in the asphalt liner of the WRL. Table 1 indicates the results of the leachate sampling from 1981 to 1984 and during 1988 to 1989. Round 5 sample results indicated contamination consistent with rounds 1 through 4.
The leachate samples taken during the RI generally contained higher concentrations of aromatic VOCs such as benzene, toluene, and xylenes than the chlorinated VOCs vinyl chloride and dichloroethene. Tetrachloroethene was detected only once and trichloroethene was not detected at all. Previous leachate sample results (1981 to 1984) generally follow these same concentration trends, indicating that the leachate composition has not changed significantly over this time span (1981 to 1990). The WRL leachate has a high inorganic component consistent with typical sanitary component leachates, except it has higher than typical chloride and sodium content.
Ambient air monitoring was conducted October 24 and 25, 1988 at the WRL site (12). The samples consisted of one upwind location northwest of the landfill and three downwind locations on the east half of the landfill on the south side. The meteorological station was located close to the center of the landfill. Winds during the sample collection were generally from the northwest at speeds varying from 0 to 10 miles per hour. The results of the air sampling indicated the presence of 15 VOCs at levels below the National Ambient Air Quality Standard for hydrocarbons (non-methane) which is 0.16 milligrams per cubic meter (12). However, the data was of limited value because sample holding times were exceeded.
Surface water samples were collected at five locations along Killbuck Creek. Four sample locations were downstream of the site and one upstream to serve as a background sample. Several inorganic compounds were chosen to serve as indicator chemicals to determine if leachate from the WRL has impacted the creek. Concentrations of the indicator compounds upstream of the site were compared to concentrations downstream to make this determination. The was no difference between upstream and downstream concentrations of indicator compounds in surface water indicating that the leachate from the landfill has not impacted the creek (12). Surface water samples were also analyzed for organic compounds. One low level concentration of chloroform (0.29 ug/l) was detected in a sample from the creek, but no other organic compounds were detected above laboratory detection limits.
Sediment samples were collected at five locations along Killbuck Creek. Four sample locations were located downstream of the site and one upstream to serve as a background sample. Several inorganic compounds were chosen to serve as indicator chemicals to determine if leachate from the WRL has impacted the creek. Concentrations of the indicator compounds upstream of the site were compared to concentrations downstream to make this determination. There was no difference between upstream and downstream concentrations of indicator compounds in sediments, indicating that the leachate from the landfill has not impacted the creek (12). Sediment samples were also analyzed for organic compounds. Chloroform and two phthalates (di(2-ethylhexyl) phthalate and di-n-butylphthalate) were detected in low concentrations below levels of health concern in sediment samples. No other organic compounds were detected in downstream sediment samples.
All samples were collected and analyzed in accordance with IEPA and USEPA protocol as agreed upon in the Quality Assurance Project Plan (QAPP). Several round 1 and 2 leachate samples were discarded due to difficulties in laboratory analyses, however, subsequent modification of analytical procedures corrected the difficulty and rounds 4 and 5 leachate data were considered useable. Holding times were exceeded for round one groundwater samples resulting in several estimated values. The data was, however, determined to be useable. Air sampling data for the WRL site were not adequate, since holding times for the samples were exceeded.
The WRL is an active, licensed landfill presenting physical hazards typical of such operations. Daily operation of heavy equipment, traffic in and out of the site, and dumping of debris all present hazards to both employees and individuals dumping at the WRL. The collection, distribution, and use of methane gas from the landfill to fuel the sludge drying facility at the site may also pose a potential explosive hazard to employees and nearby residents. An explosion did occur at the collection and storage facility in 1991 highlighting this potential concern. The cause of the explosion is suspected to have been associated with a leak and subsequent accumulation of methane gas inside of the gas storage building. No injuries were reported and damage was limited to the gas storage building on-site.
Since the reporting of toxic releases began in 1987, the USEPA has collected information on estimated annual releases of toxic chemicals by industry to the environment (air, water, land, or underground injection). This data is compiled and retrievable through the on-line database, Toxic Chemical Release Inventory (TRI). The reporting years 1987 to 1992 are currently available for review.
The TRI records were reviewed for reporting industries in the vicinity of the WRL site. No
industries within a 3-mile radius reported releases of chemicals to the environment. This was
anticipated since land use around the site is primarily agricultural or residential.
To determine whether nearby residents are exposed to contaminants migrating from the WRL, IDPH evaluates the environmental and human components that lead to human exposure. This pathways analysis consists of five elements: a source of contamination, transport through an environmental medium, a point of exposure, a route of human exposure, and an exposed population.
IDPH categorizes an exposure pathway as a completed or potential pathway if the exposure pathway cannot be eliminated. Completed pathways require that the five elements exist and indicate that exposure to a contaminant has occurred in the past, could be occurring now, or could occur in the future. An exposure pathway can be eliminated if at least one of the five elements is missing and will never be present. Table 4 identifies the completed exposure pathways and Table 5 identifies the potential exposure pathways. The discussion that follows these two tables incorporates only those pathways that are important and relevant to the site. IDPH will also discuss some of those exposure pathways that have been eliminated.
Past and future exposure pathways are possible from contamination of ambient air on-site. Potentially exposed populations include on-site workers, local residents, and trespassers. The possible route of exposure is inhalation. During air monitoring 15 VOCs were detected but the data were of limited value since sample holding times were exceeded. No VOCs detected at any sample location exceeded National Ambient Air Quality Standards. Since sampling data is unreliable, IDPH cannot evaluate past exposures.
Future exposures to VOCs from the WRL are not likely due to the gas extraction system currently in operation. Landfill gas is collected by a network of 91 extraction wells and is used as a fuel source in a sludge drying operation. During combustion of the gas, VOCs are also burned. This system is currently in operation at the site reducing the potential for present exposures.
Fugitive dust generation is not expected to be a substantial transport mechanism that may lead to exposures. Dust control measures are utilized at the site during landfilling operations. Water is sprayed on the surface of the work area, when necessary, and a clean soil cover is placed over landfilled waste to reduce the release of fugitive dusts. After closure of the landfill, it is anticipated that IEPA and USEPA will require a cap and vegetative cover as part of the final closure plan. This will reduce the potential for future exposures to fugitive dusts. The gas extraction system will also remain in place, reducing the potential for future exposures.
Residents utilizing groundwater downgradient of the WRL may be exposed to contaminants in the future. Ingestion, inhalation, and skin contact are routes of exposure that may occur during groundwater use. Residential wells located upgradient of the WRL have also been contaminated by VOCs. Groundwater flow in the area of the two sites is generally from east to west, making the Acme Solvents site upgradient from the WRL. The source of these contaminants has not yet been verified. The contaminant plume extends at least 900 feet downgradient from the western edge of the landfill. The closest private well downgradient of the WRL is located approximately 1/2 mile from the boundary. Future contamination is possible to wells located downgradient of the WRL. The rate of groundwater movement in the area has not been estimated due to the complex sub-surface.
The potential routes of exposure associated with the private wells pathway include ingestion, inhalation, and dermal contact. As stated earlier in the assessment, these exposures are not expected to occur, since the contaminated groundwater plume from the WRL site is moving to the west of the site. The nearest residence west of the site is located approximately 1/2 mile from the site boundary. As stated in the ROD, a groundwater extraction system will be installed by the owner/operator of the WRL to deter the migration of the contaminant plume and to reduce the contaminant concentrations in the groundwater. The installation of this system would eliminate private wells as a potential pathway, thus eliminating the future routes of exposure.
The private wells upgradient (east) of the site are not discussed in this assessment since the groundwater plume is moving in the opposite direction. These wells and the potential health effects associated with domestic water use are discussed in the Acme Solvents Health Assessment.
Future exposure pathways are possible from sediments in Killbuck Creek. Dermal contact is the route of exposure that would be most significant if the sediments become contaminated. Incidental ingestion is not a likely route of exposure due to the dimensions of the creek. Killbuck Creek is shallow (1 to 3 feet deep) and swimming is not a current activity in this body of water. Dermal contact with sediments during wading or fishing is the likely exposure route.
Past sampling of creek sediments has not revealed contamination above levels of health concern. Metal concentrations detected in sediments are within background concentrations or expected normal ranges based on the geologic conditions (12). Sediments may become a significant exposure pathway in the future if contamination migrates into the creek from the WRL. Since contaminants have not been detected in sediments at levels above health concern, this pathway and related exposures will not be addressed further.
Future exposure pathways are possible from surface water if Killbuck Creek becomes contaminated from the WRL. One compound, chloroform, was detected in surface water samples, however, levels were far below those of public health concern.
Residents utilizing the creek for wading or fishing may become exposed to site related contaminants by inhalation or direct skin contact in the future. Incidental ingestion is not considered a plausible exposure route since swimming is not a recreational activity in the creek. Significant exposures may occur if contaminants migrate from the WRL and contaminate the creek. Migration of contaminants may occur via groundwater discharge due to the high water table in the area.
Past, present, and future exposure pathways are possible from on-site surface soils. Trespassers and site workers may have been exposed in the past and may be exposed in the future by ingestion, inhalation, or dermal contact from contaminated soils.
No surface soil samples have been collected on-site to determine past or present contamination. Since this is an operating landfill, direct exposure to surface soils is likely, due to the landfilling activities, but exposures would be expected to be transient and difficult to evaluate. Surface soil is continually turned over as areas are covered daily with top soil. IDPH is unable to assess these exposures since no data are available.
Future exposure pathways are possible from contamination of fish in the Killbuck Creek.
Killbuck Creek is reportedly used for sport fishing. Local residents may become exposed in the
future by ingesting contaminated fish from this creek. No fish sampling has been performed,
due to the low levels of contaminants detected in the sediments and surface water. If
contaminants migrate to the creek from the WRL in the future, fish may become contaminated
representing a potential pathway.
IDPH will not discuss health effects associated with specific contaminants
detected at this site due to the lack of data for past exposures and the lack
of present exposure to site-related contaminants. Future exposures to site-related
contaminants is also unlikely due to scheduled remedial activities. Workers,
and possibly trespassers, have probably been exposed to contaminants in on-site
surface soils and ambient air, but the lack of data prevents IDPH from estimating
exposures and discussing health effects from specific contaminants. Contaminants
have been detected in groundwater monitoring wells around the perimeter of the
site above ATSDR comparison values, but the distance of the contaminant plume
is reportedly about 1/2 mile from the nearest residential well and is not expected
to reach the well if remedial activities proceed as planned. The list below
identifies contaminants detected above ATSDR comparison values in monitoring wells located on and downgradient of the site.
At this time, it is not necessary to discuss potential health effects associated with these contaminants since future exposures are unlikely. Remedial activities at this site should ensure that the contaminant plume does not reach private wells downgradient of the WRL. If the contaminant plume does migrate near these wells (i.e., absence of remediation), IDPH will address potential health effects associated with the contaminants detected in the plume. IDPH will also address health effects from exposures to sediments, surface water, fish, and surface soils if these media become contaminated in the future.
No state or local health outcome data have been reviewed for this health assessment. The populations involved living near the WRL and the Acme Solvents sites are too small for evaluation through state cancer, mortality, and adverse pregnancy outcome registries.
At the present time, known exposures are only identified with the Acme Solvents site. Members of the community around Acme Solvents are participating in ATSDR's TCE Exposure Registry and are being contacted at yearly intervals concerning their health status. Since no known exposures have been identified at the WRL, review of databases is not necessary at this time.
IDPH has addressed the community health concerns associated with this site as follows:
- What are the potential long-term health effects associated with exposure to site-related contaminants?
IDPH has identified two possible past exposure pathways: air and surface soils. Trespassers and on-site workers may have been exposed to contaminants via inhalation or dermal contact. The installation of the gas extraction system on-site should eliminate most exposure to contaminants in the air. Subsequent exposures to contaminants not captured by the system or at times the system may shut-down due to mechanical complications are considered to be minimal. Exposures may be occurring from on-site surface soils. The lack of data for air and soils prevents IDPH from estimating exposures and discussing potential health effects for these media.
No exposures have been identified off-site. Concentrations detected in off-site surface water and sediments in Killbuck Creek indicate past and present exposures have been minimal and no adverse health effects would be expected. Killbuck Creek should not be impacted in the future by the WRL, based on past sampling data and the absence of transport mechanisms, thus future exposures are not expected. Groundwater in the area has been impacted by both the WRL site and the Acme Solvents site. Private wells located upgradient of the WRL have been addressed in the Acme Solvents Health Assessment. Private well users utilizing groundwater downgradient (west) of the WRL are at a great distance (greater than 3,000 feet) from the identified plume. Remediation activities should ensure these wells are not contaminated in the future, eliminating concern for long-term health effects.
- What are the impacts from contamination to Killbuck Creek?
No impacts are expected from contamination associated with the WRL. Past sampling of the creek has verified the landfill has not contaminated surface waters or sediments to an extent to cause adverse health effects. Possible contamination from the Acme Solvents site is addressed in the Acme Solvents Health Assessment.
- Is there a health hazard from exposure to landfill gas to local residents?
As stated in previous sections of the health assessment, a gas extraction system utilizing 91 gas extraction wells has been installed at the site. The gas is used as a fuel source in a sludge drying operation. During combustion of the gas, contaminants are also burned. The gas extraction system has minimized present and future exposures to local residents.
- Is leachate escaping from the site? Is it flowing into Killbuck Creek?
During construction of the landfill, a leachate collection system was installed. The floor of the landfill was graded to drain to various manholes placed throughout the landfill. Leachate is removed by a series of eight submersible pumps that are moved to service the manholes existing in the landfill. Leachate is also periodically pumped out of the gas extraction wells. In 1992, a sanitary sewer line was installed which connects the WRL site to the Rock River Water Reclamation District, a local publicly owned treatment works (POTW). Since then, leachate has been piped to the District by sewer line. Even though the leachate system is in operation, contaminants have migrated outside the landfill boundaries through groundwater. The contaminated groundwater plume is estimated to be at least 900 feet from the western boundary. It does not appear that leachate has impacted the Killbuck Creek, based on previous surface water and sediment sampling.