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PUBLIC HEALTH ASSESSMENT

RAMAPO LANDFILL
RAMAPO, ROCKLAND COUNTY, NEW YORK

ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS

The environmental contamination data from the RI for the Ramapo Landfill site are summarized in Appendix B, Tables 1-6. The listing of a contaminant does not necessarily mean that its presence is a public health concern. Contaminants selected for further evaluation are identified and evaluated in subsequent sections of the public health assessment to determine whether exposure to them has public health significance. When selected as a contaminant of concern in one medium, that contaminant will be reported in all media where it is detected. These contaminants are selected and discussed based upon the following factors:

  1. Concentrations of contaminants on and off the site.
  2. Field data quality, laboratory data quality, and sample design.
  3. Comparison of on-site and off-site concentrations with background concentrations.
  4. Comparison of contaminant concentrations in environmental media both on- and off-site with public health assessment comparison values for (1) noncarcinogenic endpoints and (2) carcinogenic endpoints. Contaminant concentrations above a comparison value do not necessarily represent a health threat but are evaluated further to determine if exposure is of public health significance. Comparison values include Environmental Media Evaluation Guides (EMEGs), Cancer Risk Evaluation Guides (CREGs), drinking water standards, and other relevant guidelines.
  5. Community health concerns.

A. On-Site Contamination

The most recent environmental data for the Ramapo Landfill were collected as part of the RI by the environmental engineering firm URS Consultants, Inc., under contract with the Town of Ramapo. These data are used to describe the nature and extent of contamination at the site on a media-specific basis. The media sampled during the RI were air, surface water, sediments, soil, and groundwater. An attempt was made to conduct two rounds of sampling about six months apart so as to be representative of more than one season.

Ambient Air and Soil Gas

An air monitoring study was conducted during the second phase of field activities and focused upon "hot spots" identified during a pre-RI soil gas survey. The pre-RI soil gas survey consisted of 240 air and soil gas monitoring locations spaced about 100 feet apart. At each soil gas survey station three 1/4-inch diameter holes were made, two to depths of 24 inches and one to a depth of 8 inches. Organic vapor concentrations were recorded in the 8-inch and in one 24-inch hole using a photoionization detection unit (PID). The remaining 24-inch hole was monitored for explosive gases and hydrogen sulfide using an Explosive Gas Indicator (EGI). Ambient air readings which exceeded the background level were also noted.

The primary objectives of the air monitoring study were to determine the type and concentration of airborne contaminants coming from the landfill, the production and quality of landfill gases (specifically methane) and the dispersion of the existing contaminants at known on-site receptor areas (downwind from the prevailing westerly winds at the baler building and outdoor pistol range). Three air monitoring activities were conducted which consisted of point source monitoring for volatile organic compounds and methane, "hot spot" monitoring for volatile organic compounds (VOCs), and monitoring for methane quality within piezometers. No air monitoring for hydrogen sulfide was conducted.

As shown in Figure 4, the point source sampling was conducted along the line of prevailing winds towards the occupied baler building and the pistol range. The point Source Monitoring locations are identified with the prefix PS and PSR. Samples were collected above the landfill surface and/or from within piezometers using a Tedlar bag (for collection of samples for methane analysis) and Tenax tubes (volatile organic compound analysis). In addition to sampling the on-site receptor areas, point source monitoring consisted of an on-site point source (existing piezometer) sample and a background sample from an off-site location. The results of the point source sampling show the highest concentration of methane (596,900 parts per million) at the point source location (PS-2) decreasing to 700 parts per million and non-detect at sampling locations selected near the pistol range (PS-3) and baler building (PS-4), respectively. The explosive range for methane is between 53,000 ppm (5.3%) and 150,000 ppm (15%). The concentration of methane (1,100 parts per million) detected at the single upwind background sampling location (PS-1) actually exceeds the levels detected at both downwind receptor locations. Volatile organic compounds were detected at the same point source location (PS-2), and included xylene at 1.77 parts per million (ppm), ethylbenzene (0.28 ppm) and lesser amounts of several other VOCs.

Low and non-detectable levels of several VOCs were detected at the upwind background sampling location and at the two downwind receptor areas. Hotspot monitoring was conducted at three locations (VOC-1; VOC-2; VOC-3) on the landfill which had registered high PID readings during the soil gas survey. A sample was collected at each of these locations on the surface of the landfill by Tenax adsorbent tube and analyzed for VOCs. A total of twelve VOCs were detected. Acetone had the highest concentration in each sample with levels ranging from 0.005 to 0.007 ppm, which are below the comparison value.

A total of four samples, identified in Figure 4 as GS-1 through GS-4, were obtained within three piezometers and one pre-existing vent. Samples were collected in Tedlar bags and analyzed for landfill gas quality, specifically methane. Sample results showed high concentrations of methane at locations GS-3 and GS-4 (593,800 ppm and 570,600 ppm, respectively) and low concentrations at locations GS-1 and GS-2 (non-detect and 100 ppm, respectively).

During the RI, a portable combustible gas indicator (CGI) was used to monitor for flammable/explosive atmospheres in the on-site structures (baler building and weigh station). Poorly ventilated spaces such as buildings are strong candidates for flammable/explosive atmospheres. The CGI is calibrated to read percent (%) of the lower explosive limit (LEL) of a combustible gas present in the atmosphere. Most CGI's are calibrated to read accurately for methane or pentane. The lower explosive limit is the minimum amount of a gas or vapor in air needed to produce a flash of fire when an ignition source is present. If the concentration is greater than the LEL and lower than the Upper Explosive Limit (UEL), it indicates that the ambient atmosphere is readily combustible. As previously mentioned, the explosive range for methane exists when it is present between 5.3% and 15%. No positive LEL readings were detected in the baler building or weigh station.

In addition to the above activities, independent eight-hour air samples were collected upwind (LPUP-1) and downwind (LPDW-1) of the on-site leachate pond and analyzed for VOCs. VOCs were detected at the upwind and downwind locations at concentrations below comparison values, with no significant differences between upwind and downwind sample results. Once again, acetone was the compound detected at the highest concentration (0.004 ppm) in both samples. Because the air monitoring activities occurred over a one or two day period, the results do not represent the possible range of landfill gas concentrations that might occur over time. Therefore a data gap exists on how on-site air concentrations of landfill gases range over different times of the year and under various climatological conditions.

Surface Water and Sediments

Surface water and stream sediment samples were collected and tested to determine if disposal activities at the site have contaminated sediments and/or surface water through surface water runoff and/or groundwater discharge. Sampling locations are shown in Figure 5. Two rounds of surface water and stream sediment sampling were conducted during the RI, data for which is presented in the off-site contamination section. However, two on-site leachate seep samples (SW-LS-1; SW-LS-2) were collected during the first sampling round. On-site samples collected during the second round of sampling included two additional leachate samples (LIN; LEF), and a sediment sample (LPSS-1) collected from the leachate holding pond. Samples collected in both sampling rounds were analyzed for VOCs, semi-volatile compounds, pesticides/PCBs, metals, cyanide, total phenols, and indicator parameters.

Leachate seep samples SW-LS-1 and SW-LS-2 contained several metals at concentrations higher than in the upstream surface water samples. In the absence of specific public health assessment comparison values for contaminants in leachate, the sampling results for leachate are compared to comparison values for drinking water, and to standards or guidelines for groundwater, surface water and drinking water (Table 7). Comparison values (Table 7) were exceeded for the following metals: barium (5,780 micrograms per liter; mcg/L), beryllium (10 mcg/L), cadmium (149 mcg/L), chromium (564 mcg/L), cobalt (10 and 508 mcg/L), copper (705 mcg/L), iron (2,240 and 2,739,000 mcg/L), lead (918 mcg/L), manganese (674 and 78,300 mcg/L), and zinc (4,010 mcg/L). Although ingestion of significant amounts of leachate is unlikely, these contaminants will be evaluated further to determine if exposure to them could pose a public health threat. Chlorobenzene is the only detected organic compound at 1 mcg/L which is below the comparison value for this compound. A data gap exists for these two leachate seep samples because the pesticides and PCBs data were rejected.

Leachate from the on-site leachate collection system (LIN), contained nineteen VOCs and one semi-volatile compound at concentrations below comparison values. Iron (7,820 mcg/L) and manganese (1,930 mcg/L) were at concentrations which exceed comparison values. Three semi-volatile compounds were in the leachate effluent from the leachate holding pond (LEF) all at concentrations below comparison values. Metals were at similar or lower concentrations than those in the leachate influent sample (LIN). Iron (2,840 mcg/L) and manganese (923 mcg/L) concentrations exceed comparison values.

The sediment sample from the on-site leachate holding pond (LPSS-1) contained only one VOC (2-butanone) and one semi-volatile compound (bis-2-ethylhexyl-phthalate), both at concentrations below comparison values. The pesticide, dieldrin, was detected at 0.0018 mg/kg, which slightly exceeds the public health assessment comparison value for soil contaminants. The metal concentrations are generally higher than those in the off-site stream sediments. The cadmium concentration exceeds its public health assessment comparison value in soil. Further discussion of on-site surface water will be limited to leachate seeps as contact with leachate in the subsurface leachate collection system and in the leachate holding pond is not expected to occur.

Soil/Waste Material (0-8 inches)

During the RI, nine on-site shallow soil samples were collected with a bucket auger or hand trowel, some being strictly soil (SPS-6 through SPS-10) and others containing waste materials (SPS-1 through SPS-4). Sampling depths generally ranged from 0 to 8 inches. Sample locations are shown on Figure 5. Table 1 is a summary of the sampling data for on-site shallow soil.

The results of analysis for sample SPS-9 are considered by URS to be representative of natural conditions near the site. No organic compounds were detected in this sample. A total of 18 metals were detected in SPS-9, all at concentrations below typical background ranges and available comparison values for metals in soil. Although only one background shallow soil sample was collected (during the RI), additional samples (from either on-site or off-site locations) taken from undisturbed areas would likely provide data indicative of background conditions. Of the metals in the remaining eight on-site shallow soil samples, all are within the typical background range for metals in soil. Volatile organic compounds were below public health assessment comparison values.

A total of 22 semi-volatile organic compounds were detected in the eight on-site samples and consisted primarily of polycyclic aromatic hydrocarbons (PAHs), at concentrations below the typical background range and available comparison values.

Pesticides were not widespread across the site. A low concentration of heptachlor epoxide was detected in SPS-3 and similarly low concentrations of dieldrin, alpha- and gamma-chlordane in SPS-6.

Subsurface Soil (4-6 feet)

Subsurface soil by ATSDR's definition is more than 3 inches deep. Only the subsurface soil sample identified as MW-5-SB is within the property boundary. MW-5 was taken above the water table at a depth between 4 and 6 feet below the surface. URS considers this sample to be representative of background conditions. Parameters analyzed for include VOCs, semi-volatile compounds, pesticides/PCBs, metals, and several miscellaneous indicator parameters. Excluding acetone at 0.016 mg/kg, no other VOCs were detected in MW-5-SB. No semi-volatile compounds were detected. A data gap exists for pesticides/PCBs as the sampling results for these parameters were rejected for QA/QC reasons. Sixteen metals were detected, all at concentrations below typical background ranges and public health assessment comparison values.

Groundwater - Monitoring Wells

A total of 28 groundwater monitoring wells were installed at the Ramapo Landfill site to investigate the hydrogeology of the site and to collect groundwater samples. The wells were installed in the shallow overburden aquifer, eight in the intermediate aquifer, and ten in the bedrock aquifer. The locations of the monitoring wells are shown in Figure 5. For purposes of distinguishing between on-site and off-site locations, only well clusters MW-5 and MW-6 are considered as on-site based on their placement within the property boundary. Two rounds of groundwater sampling were conducted. The first sampling round was conducted in January 1990 and round two was conducted in September 1990. Both rounds included samples obtained from the 28 wells installed during the RI and, in addition, during the second round, water from an off-site private well (GDT-1) was sampled. Samples were analyzed for VOCs, semi-volatile compounds, pesticides/PCBs, metals and other miscellaneous parameters (due to QA/QC violations, no data exists for semivolatiles in the shallow well MW-5-OS).

The on-site monitoring well cluster identified as MW-5 is located on the upgradient edge of the landfill. As such, URS considers these wells to be background and representative of natural conditions in the area. However, between both sampling rounds, six VOCs, one semi-volatile compound and one pesticide were detected in this well cluster. Of these contaminants, bis(2-ethylhexyl)phthalate is the only organic compound which exceeds a comparison value (the US EPA drinking water standard) and therefore, will be further evaluated in the Public Health Implications section of this report. Metals (unfiltered) detected at concentrations which exceed NYS DOH drinking water standards (Table 7) are chromium (up to 143 mcg/L), iron (up to 27,000 mcg/L) and manganese (up to 981 mcg/L). Aluminum was detected above US EPA's secondary maximum contaminant level (MCL) in drinking water. Secondary levels are nonenforceable taste, odor, or appearance guidelines. These metals will be further evaluated in the Public Health Implications section of this public health assessment. The presence of these contaminants in MW-5 creates uncertainty as to the designation of this well cluster as background. The absence of additional background data for this medium also creates doubts as to whether or not these data are indicative of natural groundwater conditions. The on-site monitoring well cluster MW-6 was installed to provide data for the second round of sampling. Low concentrations of about fourteen VOCs, all of which were at concentrations below NYS DOH drinking water standards, were detected in groundwater samples obtained from this cluster. No semi-volatile compounds were detected in well cluster MW-6. Metals (unfiltered) detected at concentrations which exceed NYS DOH drinking water standards are iron (up to 10,6000 mcg/L), manganese (6,770 mcg/L), mercury (2.3 mcg/L), and sodium (23,900 mcg/L). Aluminum was detected above US EPA's secondary MCL for this compound in drinking water. This report includes a discussion of these metals in the Public Health Implications section.

Groundwater - Private Wells

On March 17, 1992, tap water from the on-site baler building was sampled by the NYS DOH. Samples were analyzed for VOCs, semi-volatile compounds, and metals. Sampling did not detect any contamination.

B. Off-Site Contamination

Toxic Release Inventory (TRI)

To identify possible facilities that could contribute to environmental contamination at or near the Ramapo Landfill and/or create health threats unrelated to the site, the NYS DOH searched the 1989 Toxic Chemical Release Inventory (TRI). TRI is developed by the US EPA from the chemical release (air, water, and soil) information provided by certain industries. A search of the TRI facilities list was conducted to identify those industries located near the Ramapo Landfill (within 2.5 miles) which citizens (living near the site) may also be exposed to. Using a screening method developed by the NYS DOH, two TRI facilities were identified as reporting 1989 air emissions. These facilities are "Decorative Industries, Inc.", and "Ciba-Geigy Corporation", which are located west and southeast of the site, respectively (Figure 6). Decorative Industries reported the following releases to the environment via stack or point air emissions: Isopropyl alcohol-250 pounds per year; toluene-250 pounds per year. The Ciba-Geigy Corporation reported annual air emissions (fugitive nonpoint and stack or point) of dichloromethane at 21,775 pounds per year and methanol at 11,474 pounds per year. Based on TRI data and air emissions modeling, results of the screening evaluation indicate that the contribution of these two industrial facilities to health risks in the community around the Ramapo Landfill site is minimal.

Ambient Air and Soil Gas

Off-site ambient air and soil gas samples have not been collected.

Surface Water and Sediments

Two rounds of off-site surface water/sediment sampling were conducted during the RI. During the first phase of sampling, a total of two surface water samples were collected at two locations in Torne Brook (SW-2; SW-3), one location in the Ramapo River (SW-1), and one in a small swale draining the southern portion of the site (SW-4). Surface water samples collected during the second round of sampling consisted of three new locations along Torne Brook (SW-6, SW-7, SW-8) and resamples from the same locations identified as SW-1, SW-3, and SW-4. Sample SW-5 was taken at the same location previously sampled and identified as SW-2. Figure 5 shows the locations of the 8 surface water sampling points and Table 2 reports the contaminants and concentration range.

Sample SW-5 collected from Torne Brook upstream of the landfill and considered to be representative of background conditions, demonstrated the presence of vinyl chloride and oil and grease (1.1 mg/L). The concentration of vinyl chloride detected exceeds the comparison value recognized for this contaminant. However, based on the location of SW-5, the landfill is not considered a likely source for this contamination. No semi-volatile compounds were detected in any of the off-site surface water samples. Of the metals detected in the background samples (SW-2 and SW-5), only thallium slightly exceeds the respective comparison value in SW-2. Metals detected in downstream samples (in either the Torne Brook or Ramapo River) which exceed the same comparison value or NYS DEC standard include antimony (SW-1), iron (SW-1 and SW-8), manganese (SW-1), and thallium (SW-4). These metals will be further evaluated in the Public Health Implications section.

On July 12, 1991, the NYS DEC conducted supplemental surface water sampling of the Ramapo River. Samples were collected upstream of the former outfall, at the confluence with the former outfall, and downstream of the outfall. Results of sampling for the parameters analyzed for indicate that the contamination noted previously at SW-1 is no longer occurring due to the diversion of leachate to the Suffern sewage treatment facility.

Composite sediment samples were collected at surface water sample locations SW-1 through SW-8 and labeled SS-1 through SS-8. Samples were analyzed for VOCs, semivolatile compounds, pesticides/PCBs, and metals. Figure 5 shows the locations of the 8 sediment sampling points, and Table 3 reports the contaminants and concentration range. Samples collected from Torne Brook upstream of the landfill (SS-2, SS-5) and considered to be background showed no organic compounds and a total of 17 metals, all at concentrations below comparison values. Similar concentrations of these metals were generally found in the downstream samples. The presence of organic compounds in any of the downstream samples is limited to SS-3 whereas three semi-volatile compounds were detected at concentrations below available comparison values. Results of analysis of the sediment sample collected from a drainage swale at an adjacent property along the southern portion of the landfill (SS-4) indicate the presence of semi-volatile contaminants, primarily PAH compounds below available comparison values. In addition, the pesticide, gamma-chlordane, was detected in SS-4 below the comparison value for this chemical.

Soil/Waste Material (0-8 inches)

A shallow soil sample identified as LSMW-10 was taken off-site at a location where a leachate seep was observed near monitoring well cluster MW-10. This soil sample was collected instead of a leachate sample because at the time of sampling there was insufficient leachate to allow the collection of a liquid sample. No organic compounds were detected at levels of concern in the single off-site shallow soil sample.Of the metals detected, only cadmium at 3.7 milligrams per kilogram (mg/kg) and copper (30 mg/kg) were found at concentrations slightly exceeding the typical background range. However, these concentrations were below the respective comparison values.

A sample of paint sludge identified as SPS-5 was obtained from an off-site location between Torne Valley Road and Torne Brook. Comparison values (see Table 1) were exceeded for the semi-volatile compound naphthalene at 16 mg/kg; and the metals antimony (97.9 mg/kg), barium (11,300 mg/kg) and chromium (1,510 mg/kg). Removal of the paint sludge and surrounding soil was undertaken in the Fall of 1990 by the NYS DEC. A site visit made by the NYS DOH in March 1992 encountered paint sludge material at off-site areas between Torne Valley Road and Torne Brook.

Subsurface Soil (1-13 feet)

A summary of off-site subsurface soil data is provided in Table 4. A total of six subsurface soil samples were taken from off-site monitoring well borings installed at locations downgradient from the two landfill lobes. Off-site subsurface soil samples are identified as MW-1-SB, MW-2-SB, MW-3-SB, MW-4-SB, MW-7-SB, and MW-8-SB and are located coincident with the same numbered monitoring wells (Figure 5). All samples were taken above the water table and all but MW-4-SB (collected at a depth of 1 to 4 feet) were taken at a depth between 4 feet to 13 feet. Samples were analyzed for VOCs, semi-volatile compounds, pesticides/PCBs, metals, and several miscellaneous indicator parameters. Acetone and toluene were the only VOCs detected. Semi-volatile compounds (six) were detected only in MW-3-SB, and mainly consisted of PAH compounds. Detected organic compounds were present at concentrations below available public health assessment comparison values. Neither pesticides nor PCBs were detected, although it must be noted that three of the six sample results for pesticides and PCBs were rejected due to QA/QC violations. Metals were detected at concentrations below or near the typical background range.

Groundwater - Monitoring Wells

As previously mentioned in the "On-Site Contamination" subsection, with the exception of monitoring well clusters MW-5 and MW-6, the remaining 22 monitoring wells sampled during the RI are located outside of the property boundary and are therefore considered to be off-site wells. A summary of off-site monitoring well data is presented in Tables 5 (Round 1) and 6 (Round 2).

In sampling round one, no VOC compounds were detected at concentrations exceeding comparison values (Table 7). However, the semi-volatile compound, bis(2-ethylhexyl)phthalate was detected at low concentrations but may be due to laboratory contamination. Six metals (unfiltered) were detected at concentrations exceeding comparison values and therefore will be further evaluated.

In the second sampling round, the only VOC which exceeds a comparison value is chlorobenzene. This VOC will be further evaluated. Di-n-octylphthalate is the only semi-volatile organic compound detected at a concentration which exceeds a comparison value. This compound will also be further evaluated. In addition, bis(2-ethylhexyl)phthalate was detected at a concentration in exceedance of the comparison value for this compound. In sampling round two, seven metals (unfiltered) were detected at concentrations in exceedance of comparison values.

Groundwater - Private Wells

During the second round of groundwater sampling, water from the pump house of an adjacent property owner was sampled and labelled GDT-1 (Figure 5). The pump house draws groundwater from the residential well (PW-1) and supplies it to the residents of Torne Brook Farm. GDT-1 was analyzed for VOCs, semi-volatile compounds, pesticides/PCBs, and metals. Sampling results indicate the presence of tetrachloroethane at 0.6 mcg/L and twelve metals. The concentration of tetrachloroethane and all metals detected are below comparison values. On December 16, 1991, this supply was sampled by the RC DOH and analyzed for volatile organic compounds and metals. Results of analysis indicate no organic contamination and all metals detected are below comparison values. According to RC DOH records, tetrachloroethane has also been detected in this supply in May 1981 and in October 1988 below comparison values on both occasions.

On March 17, 1992, water from a nearby residence on Torne Brook Road (PW-2) was sampled by the NYS DOH and analyzed for VOCs, semi-volatile compounds, and metals. Results of testing indicate no contamination.

Groundwater - Public Supplies

The Spring Valley Water Company provided URS with water quality information regarding Spring Valley Water Company wells 94, 95 and 96. Figure 5 shows the locations of these public supply wells. Samples were analyzed for VOCs, pesticides, metals, and several miscellaneous indicator parameters. Sampling did not detect any contamination.

C. Quality Assurance and Quality Control (QA/QC)

In preparing this public health assessment, the NYS DOH relied on the information provided in the referenced document and assumed that adequate quality control measures were followed with regard to chain of custody, laboratory procedures, and data reporting. The analyses and conclusions in this public health assessment are valid only if the referenced information is correct.

Due to QA/QC violations, pesticides and PCB data are unavailable for the on-site leachate seep samples, for the on-site subsurface soil sample MW5-SB, and for three of six off-site subsurface soil samples collected during the RI.

The semivolatile compound, bis(2-ethylhexyl)phthalate, was detected at low concentrations in various media sampled during the RI. The presence of this chemical at the concentrations detected is suspect and may be attributed to laboratory contamination.

D. Physical and Other Hazards

Portions of the landfill are steep and/or eroded, conditions which may create insecure footing. Therefore, persons accessing the landfill are faced with an increased risk of injury resulting from slips and falls.

PATHWAYS ANALYSES

To determine whether nearby residents and persons on-site are exposed to contaminants migrating from the site, an evaluation was made of the environmental and human components that lead to human exposure. The 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.

An exposure pathway is categorized as a completed or potential exposure pathway if the exposure pathway cannot be eliminated. A completed exposure pathway occurs when the five elements of an exposure pathway link the contaminated source to a receptor population. Should a completed exposure pathway exist in the past, present, or future, the population is considered exposed. A potential exposure pathway exists when one or more of the five elements is missing, or if modeling is performed to replace real sampling data. Potential pathways indicate that exposure to a contaminant could have 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. The discussion that follows incorporates only those pathways that are important and relevant to the site.

A. Completed Exposure Pathways

No completed exposure pathways have been identified for this site.

B. Potential Exposure Pathways

Ambient Air/Soil Gas Pathways

Past, current, and future exposure pathways are possible from contamination of the ambient air on-site and at the adjacent residential area. Populations at risk of exposure to contaminated ambient air via inhalation include the following: persons trespassing on the site for recreational purposes; persons using the on-site pistol range; employees at the on-site baler facility and weigh station; and residents of nearby dwellings.

Landfill gases produced from the degradation of buried wastes have migrated upward through the cover material on the landfill. Landfill gas contains about 60% methane and 40% carbon dioxide. Under certain conditions, landfill gas may also contain volatile organic compounds which can volatilize through surface soils into the atmosphere. Persons on-site could be exposed to contaminants volatilizing from the landfill at any point on the site. The primary route of exposure is inhalation of airborne chemicals. Contaminants released to ambient air (breathing zone) will likely be dispersed and diluted at unconfined on-site and off-site areas. Testing of landfill gas within on-site piezometers indicates the presence of xylene and ethylbenzene. However these chemicals were not detected at levels exceeding comparison values in ambient air at on-site receptor areas.

Site contaminants could also migrate through porous media as soil gas and enter confined building spaces (basements) through crawl spaces, plumbing holes, other floor holes (e.g., sumps) and foundation cracks, and contaminate indoor air in on-site (baler building/weigh station) and off-site buildings. Limited data on landfill gas generation indicate that the on-site methane levels could pose a public health threat. One public health threat from methane generation is the potential for explosive levels of methane that accumulate in closed buildings and hence be a safety problem. Another public health threat is that toxic gases tend to be carried with methane. Also, oxygen depletion may result if a significant quantity of landfill gas is present.

Testing of ambient air for toxic chemicals has been limited to the on-site baler building and pistol range and one off-site location. VOCs tested for are present at levels typical of normal atmospheric conditions. A data gap exists for hydrogen sulfide which has not been tested for at the site. At this time, the soil gas/ambient air exposure pathway is categorized as a potential human exposure pathway since limited quantitative data exist to fully evaluate this pathway.

As mentioned previously in the Off-Site Contamination section, ambient air monitoring has not been conducted at the residential area near Torne Brook Road. Due to the lack of data, it is not possible to determine the extent of soil gas contamination from the site and whether the site is responsible for the odors detected at Torne Brook Farm.

Waste Material/Leachate Seep Pathway

The potential exists for exposure to site related contaminants, specifically metals, present in on-site leachate seeps. Populations at risk of exposure to contaminated leachate include persons trespassing on the site and persons using the on-site pistol range who could be exposed by skin contact or incidental ingestion. Trespassers observed on-site have been primarily hikers or adults operating all-terrain vehicles and the potential for any significant exposures to leachate appears to be very low.

The leachate could also be contributing metals to on-site and off-site soil, however the limited sampling of soil to date does not indicate the presence of metals at levels of concern.

The off-site disposal of paint sludge presents a potential for exposure to persons via direct contact and/or incidental ingestion of the waste material.

Surface Water/Sediment Exposure Pathway

As previously mentioned in the Background section of this public health assessment, the surface water features near the site are the Ramapo River, Torne Brook, and Candle Brook. Public concern has been expressed regarding potential exposure to surface water contaminated by the landfill. Of particular concern is an area on the Ramapo River referred to "Flat Rock", which is reportedly used for recreation, including swimming and fishing.

Site related contaminants could be transported to adjacent surface water bodies via precipitation runoff flowing down the landfill and/or groundwater discharge from the shallow aquifer underlying the site. In addition, a significant portion of contamination detected in the Ramapo River could be related to the discharge of treated leachate from the on-site leachate collection system directly into the river. Contaminants which have entered the nearby Torne Brook and Ramapo River are available for direct contact or incidental ingestion for persons, particularly children, who might be swimming in these off-site areas. The presence of vinyl chloride in surface water samples from Torne Brook is likely due to upstream contamination, the source of which has not been determined. Notwithstanding, there is some evidence of a landfill effect upon Torne Brook which now appears relatively minor. Since only limited surface water sampling was performed during the RI, there is some uncertainty regarding potential exposure to surface water at "Flat Rock". However, based on current data, the likelihood for exposure to site related contaminants at "Flat Rock" is expected to be low. This conclusion is further supported by the fact that discharge of treated leachate to the Ramapo River has ceased, thus removing a likely source of contamination.

Groundwater Exposure Pathway

Three groundwater producing units have been identified as underlying the site: a shallow aquifer consisting of loose and dense sands with abundant boulders and cobbles; an intermediate layer within a thin zone of weathered rock; and a bedrock aquifer. Depth to bedrock ranges from zero (outcrops near the site) to greater than 65 feet.

The water table surface closely parallels the surface topography and shallow groundwater generally flows towards Torne Brook which is a topographic low between the landfill and lands between the brook and the Ramapo River. Much of the flow in the shallow aquifer is intercepted by the leachate collection system along Torne Valley Road. The flow direction in the intermediate and bedrock aquifer is likely very similar to that of the water table aquifer but in all probability flows beneath Torne Brook to the Ramapo River. Groundwater contamination has been detected in all three aquifers in both on-site and off-site monitoring wells. To date, testing of the private drinking water supply well at Torne Brook Farm, at the residence identified as PW-2 and at the on-site baler building, has not detected any site-related contaminants at levels of concern. Future contamination of these wells is possible should contaminated groundwater migrate to these well locations. The possibility also exists for future contamination of the nearby Spring Valley Water Company supply wells, which to date have not been affected by site-related contaminants.

Exposures to contaminants in drinking water supplies occur via ingestion; dermal contact and absorption during showering, bathing, or other household uses ;and inhalation of aerosols and vapors from water used in the household.

Populations at risk of exposure to contaminated groundwater include the following: tenants at Torne Brook Farm; tenants at the nearby residence identified as PW-2; employees at the baler building, and individuals connected to the Spring Valley Water Company distribution system.

C. Eliminated Exposure Pathways

Soil Pathways

Chemicals in shallow and subsurface soil at the site are at concentrations below typical background levels and/or public health assessment comparison values. Therefore, we will eliminate the soil exposure pathway from further evaluation in the public health assessment.

Fish Pathways

No data are available for fish samples from the streams in the area. Fishing occurs in the Ramapo River; however, the extent is not known. Contaminants of concern attributable to the landfill and discharging to Torne Brook will be greatly reduced in the Ramapo River. Furthermore, the contaminants of concern in Torne Brook and the Ramapo River have not been found at elevated levels in the sediment of these streams. Therefore, fish bioaccumulation is not expected to result in a human exposure pathway and will not be discussed further in this public health assessment.

PUBLIC HEALTH IMPLICATIONS

A. Toxicological Evaluation

On-site groundwater, leachate seeps and landfill gas at the Ramapo Landfill and off-site groundwater monitoring wells and surface water are contaminated at levels of concern for potential human exposure pathways (Tables 2, 5 and 6). There have been no documented past or current exposures to contaminants at the Ramapo site. However, residents are concerned about potential contamination of nearby drinking water supply wells. An analysis of the toxicological implications of the potential human exposure pathways of concern is presented below:

  1. Potential ingestion, dermal and inhalation exposure to contaminants in private wells as a result of contaminant plume migration.

    As indicated in Tables 5 and 6, off-site groundwater monitoring wells are contaminated with volatile and semi-volatile organic compounds and metals at concentrations that exceed comparison values (Table 7). On-site groundwater is also contaminated with these chemicals. There is a potential for oral (ingestion), dermal and inhalation exposure to contaminants in residential well water from contaminated groundwater. This pathway is incomplete since migration to residential wells has not been identified and therefore no known exposure is occurring. There is also a potential for oral exposure to contaminants in on-site groundwater by workers in the baler facility, however, to date, site related contaminants have not been detected in this supply.

    Volatile and Semi-Volatile Organic Compound Contaminants

    The semi-volatile compound, bis(2-ethylhexyl)phthalate, was detected at low concentrations in fourteen of 28 groundwater samples (Tables 5 and 6). The presence of this chemical at the concentrations detected is suspect and may be the result of laboratory contamination.

    Bis(2-ethylhexyl)phthalate causes cancer in laboratory animals exposed to high levels over their lifetime (ATSDR, 1991a). Chemicals that cause cancer in laboratory animals may also increase the risk of cancer in humans exposed to lower levels over long periods of time. Based on the results of animal studies, chronic (lifetime) exposure to bis(2-ethylhexyl)phthalate at the highest concentrations found in groundwater monitoring wells would pose a low increased cancer risk.

    Bis(2-ethylhexyl)phthalate and di-n-octylphthalate can cause kidney, liver, and male reproductive system damage (ATSDR, 1991a) and chlorobenzene can cause nervous system, liver and kidney damage (ATSDR, 1989a) at exposures several orders of magnitude greater than potential exposures to groundwater. Chemicals that cause effects in humans and/or animals after high levels of exposure may also pose a risk to humans who are exposed to lower levels over long periods of time. Although the risk of noncarcinogenic effects from these potential exposures isn't completely understood, the existing data suggest it would be minimal.

    Metal Contaminants

    Exposure to chromium can increase the risk of kidney damage, birth defects and reproductive effects (ATSDR, 1991b). Chronic exposure to elevated lead levels is predominantly associated with neurological and hematological effects (ATSDR, 1991c). The developing fetus and young children are particularly sensitive to lead-induced neurological effects. Exposure to high manganese concentrations can cause nervous system effects (ATSDR, 1990b). Exposure to high levels of nickel can cause reproductive effects and allergic reactions (ATSDR, 1988). Little is known about the chronic toxicity of aluminum in humans. Some animal toxicity studies indicate that a relatively high dose of aluminum may cause nerve and skeletal damage and may adversely affect the reproductive system (NYS DOH, 1990). Although iron is an essential nutrient, ingestion of large amounts can lead to accumulation in the body and tissue damage (WHO, 1984). The levels of aluminum, iron and manganese in groundwater monitoring wells are over 95, 750 and 620 times the levels, respectively, at which the aesthetic quality of drinking water begins to be affected (WHO, 1984). Water containing more than 20,000 mcg/L of sodium should not be used for drinking by people on severely restricted diets and water containing more than 270,000 mcg/L of sodium should not be used for drinking by people on moderately restrictive diets. Exposure to drinking water contaminated with these metals, in particular chromium, manganese and lead, at the highest concentrations found in groundwater monitoring wells could pose a moderate increased risk of adverse health effects.

  2. Potential ingestion, inhalation and dermal exposure of persons coming into contact with contaminated on-site leachate seeps, landfill gas, and off-site soil/paint sludge material.

    The potential for on-site exposure to contaminated surface water and landfill gas can occur since site access is possible.

    On-site leachate seeps and off-site paint sludge are contaminated with metals including antimony, barium, beryllium, cadmium, chromium, cobalt, copper, iron, lead, manganese and zinc. Incidental ingestion exposure to these metals could present an increased public health risk, especially to children who could play in these areas on a frequent basis.

    Limited landfill gas sampling on-site indicates a potential for exposure to methane gas. One public health threat from methane generation is the potential for explosive levels of methane to migrate off-site and accumulate in closed buildings, such as the baler facility, weigh station, and adjacent homes, and hence be a safety problem. These risks are in addition to the effects that can be caused by large amounts of methane displacing oxygen in air. Individuals who continue to breathe high levels of methane may become dizzy, experience difficulty in breathing or loose consciousness (Sax, 1979). In addition, toxic gases may be carried with methane, which if inhaled can result in adverse health effects.

  3. Potential ingestion, dermal and inhalation exposure of persons engaged in recreational activities in adjacent streams.

    Potential runoff of contaminants in on-site leachate seeps and surface runoff could impact surface water and sediments in Torne Brook stream and the Ramapo River. These waters are used for recreational purposes including swimming and fishing. As indicated in Table 2, initial sampling of off-site surface waters found several metals at concentrations which exceed comparison values. Subsequent sampling of the Ramapo River indicates that the contamination is no longer occurring due to the diversion of on-site leachate to the Suffern sewage treatment plant. Past exposure to contaminants at the highest levels previously detected in off-site surface water and sediments (Tables 2 and 3) is unlikely to result in any adverse health effects.

B. Health Outcome Data Evaluation

Cancer Incidence and Mortality Data

A review of the 1978-82 cancer incidence and mortality data in Census tract 117 (Sloatsburg) and Census tract 116 (Ramapo Town) found no significant excess in total cancer or cancer of any of 17 common sites of cancer when compared to the mortality and incidence rates of New York State excluding New York City.

C. Community Health Concerns Evaluation

We have addressed each of the community concerns about health as follows:

  1. Will residents living near the landfill be provided with public water, and if so, when?

    To date, results obtained from sampling of nearby private wells indicate that the wells are not being contaminated by the landfill. Therefore, no provision for an alternate water supply is warranted at this time. However, should future groundwater monitoring data indicate that drinking water standards are being exceeded in nearby wells, then an alternate water supply may be deemed necessary. If drinking water standards are exceeded for site-related contaminants in residential wells, and/or significant concentrations are detected in the same aquifer in the closest monitoring wells to the residential wells, and detected concentrations are confirmed by subsequent sampling, residents would immediately be provided with bottled water and/or an acceptable treatment system. This interim measure would remain in effect until a permanent alternate water supply could be constructed.

  2. Will measures be taken to ensure the overall protection of health of persons living near the site?

    The selected clean-up remedy for the site is expected to achieve protection of human health. The planned capping of the landfill protects human health by reducing the mobility of contaminated materials. In addition, capping the landfill will eliminate threats to persons who come in contact with the landfill. Long-term monitoring of the site will be performed to ensure that residential drinking water wells are protected from contamination coming from the site. Air monitoring will be performed prior to, during, and following clean-up construction at the site to ensure that air emissions resulting from the cap construction meet air quality requirements. Landfill gas emissions will be controlled, if necessary.

  3. Will an appropriate monitoring program be provided to determine the presence of contaminants encroaching on or in nearby drinking water supply wells?

    As part of the selected remedy for the site, groundwater samples will be collected on a quarterly basis from nearby residential wells and from new and existing monitoring wells. Samples will be tested for site-related contaminants. Early warning monitoring wells will be installed where needed between the site and private residential drinking water wells and also between the site and the nearby Spring Valley Water Company production wells. These production wells will be sampled quarterly for contaminants associated with the site, for the first year of long-term monitoring, or longer if contamination is noted.

  4. Complaints by Residents about Landfill Odors.

    It is not known if the landfill odors are from garbage handled at the active baler building or is caused by the migration of hydrogen sulfide emitted at the site. Limited ambient air sampling has only been performed on-site and did not include measurements for hydrogen sulfide, which is known to have a rotten-egg odor. While chronic exposure to hydrogen sulfide may cause adverse health effects, additional air data are needed both on-site and off-site to determine the health significance of these odors.


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