OYSTER BAY, NASSAU COUNTY, NEW YORK
A summary of the environmental contamination data collected during the RI for the Syosset Landfill site is presented in Appendix B, Tables 1-4. 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:
- Concentrations of contaminants on and off the site.
- Field data quality, laboratory data quality, and sample design.
- Comparison of on-site and off-site concentrations with background concentrations.
- Comparison of on-site and off-site contaminant concentrations in specific media with public health assessment comparison values for (1) noncarcinogenic endpoints and (2) carcinogenic endpoints. These values include Environmental Media Evaluation Guides (EMEGs), Cancer Risk Evaluation Guides (CREGs), drinking water standards and other relevant guidelines.
- Community health concerns.
The most recent environmental data for the Syosset Landfill site were collected as part of the OU-1 RI by the environmental consulting firm Geraghty & Miller, Inc. under contract to the Town of Oyster Bay. These data are used to describe the nature and extent of contamination at the site on a media specific basis. The on-site media sampled during the RI were soil gas, subsurface soil and groundwater. In addition, ambient air was tested by NC DOH in June and July 1991.
Soil Gas/Ambient Air
Landfill gas was measured during the RI on a monthly basis by monitoring 19 shallow gas monitoring wells installed throughout the site (see Appendix A, Figure 4). Landfill gas samples were analyzed for methane and total volatile organic compounds (VOCs). High concentrations of landfill gases were detected in the central part of the landfill and in the southwestern corner of the landfill. Field measurements with a Organic Vapor Analyzer (OVA) found methane levels ranging from 0 to greater than 100,000 (0-10%) parts per million and non-methane VOCs ranging from 0 to greater than 0.4 ppm. These findings are not uncommon for municipal landfills. Table 1 in Appendix B summarizes sampling results for samples of landfill gas collected for laboratory analysis from ten gas monitoring wells exhibiting the consistently highest concentrations of methane and non-methane compounds. Contaminants of concern in this medium are identified in the table.
A passive gas ventilation system consisting of a trench along the landfill property line (which parallels the fence separating the site from the South Grove Elementary School) and a series of gas vent wells have been monitored since 1981. In March 1983, landfill gas vent samples were taken on the landfill side of the trench by the Nassau County Department of Health (NC DOH) contained methane and VOCs at levels above comparison values (see Appendix B, Table 2). Recent monitoring of the ventilation system for total combustible gases conducted by the Town of Oyster Bay found that landfill gas does occasionally migrate to the school side of the trench when the trench becomes clogged with soil. However, there is routine maintenance of the trench to ensure its operation. In addition, methane meters which are located in the school building, have never detected methane gas.
In March 1983, buildings on the landfill were tested for the presence of methane and none was detected.
Ambient air and landfill gas monitoring wells were sampled at the Syosset Landfill by NC DOH in June and July 1991. This limited study included the collection and analysis of air in soil gas monitoring wells adjacent to the landfill gas ventilation trench and ambient air up and downwind of the trench. Total sampling time for each sample was twenty-five minutes. Samples were tested for VOCs and field measurements were taken for methane, hydrogen sulfide, and combustible gas levels during the July sampling. On both sampling dates, the wind was blowing from the west/northwest whereas the South Grove School property was downwind. Trace amounts of VOCs were detected in the gas monitoring wells and in the upwind and downwind ambient samples. Technical problems were encountered which resulted in the rejection of VOC data for several soil gas samples. Methane levels ranged from 0-22% and hydrogen sulfide levels were measured from 0 ppm to 10.2 ppm. In the ambient air samples trace amounts of VOCs were detected which included tetrachloroethene (3-6 micrograms per cubic meter [mcg/m3]), toluene (6 mcg/m3), xylene (6-38 mcg/m3) and 1,1-dichloroethane (66 mcg/m3). Five new gas monitoring well clusters (ten wells) will be installed under the OU-1 remedial design program, which is currently on-going.
Subsurface Soil/Waste Material
During the RI, three subsurface soil samples were collected from each of four on-site soil borings. Sampling locations are identified in Appendix A, Figure 2 as B1-B4. Sampling depths ranged from 15 feet to 183 feet. Samples were analyzed for VOCs, PCBs, semivolatile organic compounds, and leachable metals. Sampling data are presented in Appendix B, Table 3. Organic compounds which exceed comparison values are vinyl chloride, bromodichloromethane, naphthalene, bis(2-ethylhexyl)phthalate, benzo(a)pyrene, Aroclor 1016 and Aroclor 1254. Antimony is the only metal detected which exceeded its comparison value and as such will be recognized as a contaminant of concern.
Groundwater - Monitoring Wells
Two rounds of groundwater samples were collected from 15 on-site monitoring wells in May and June 1988. Eleven of the wells were installed in the shallow (Upper Glacial) aquifer and ranged in depth between 120-153 feet below the landfill surface. The four remaining wells were installed in the deeper (Upper Magothy) aquifer and ranged in depth between 215-240 feet below the landfill surface. Figure 2 in Appendix A shows the locations of these monitoring wells, and Table 4 in Appendix B reports the contaminants and concentration range. Samples were analyzed for VOCs, semi-volatile organic compounds, PCBs, and metals. Two samples, filtered and unfiltered, were collected from each well for metals analyses. Only filtered samples were collected from each well for metals analyses during the second sampling round. Organic compounds detected at concentrations which exceed comparison values are 1,2-dichloroethene, trichloroethene, tetrachloroethene, and chlorobenzene. These VOCs will be recognized as contaminants of concern.
Metals detected at concentrations which exceed comparison values are antimony, arsenic, lead, thallium, sodium, barium and iron. These metals will be recognized as contaminants of concern.
Soil Gas/Ambient Air
In July 1981, off-site soil gas sampling was performed by the NC DOH on South Grove School property in the area adjacent to the Syosset Landfill. This testing found methane levels up to 10 percent in the soil. Subsequent sampling in 1981 and 1982 on school property did not detect methane within the school buildings or surrounding soil.
Off-site soil gas/ambient air was not tested during the OU-1 RI since it was an on-site investigation.
Off-site surface water/sediment samples have not been collected as there are no nearby surface water bodies.
Subsurface soil samples were not collected at off-site locations during the OU-1 RI. This will be performed during the OU-2 off-site investigation.
Surface soil samples were not collected at off-site locations. This will be performed during the OU-2 off-site investigation.
Groundwater - Monitoring Wells
Off-site monitoring wells were not installed during the OU-1 RI. This will be performed during the OU-2 off-site investigation.
Groundwater - Private Supply Wells
Off-site private industrial wells were not sampled during the OU-1 RI.
Groundwater - Public Supply Wells
Potable water in the area surrounding the Syosset Landfill is supplied through public water supplies derived entirely from groundwater wells. As previously mentioned in the Background section, three public drinking water supply wells are within a 1-mile radius of the site. These wells are upgradient of the site. Prior to 1974, one downgradient public drinking water supply well identified as N4133, was in use. The use of this well was discontinued in July 1974 due to taste and odor problems. The well was subsequently sealed in 1982. Limited sampling data for this well from April 1954 until July 1974 showed ammonia-nitrogen up to 1,500 mcg/L. Well N4133 was tested for VOCs including the US EPA Priority Pollutants between 1977 and 1980. VOCs were either not detected or when detected were at or slightly above the detection limits at the time (generally less than 1 mcg/L).
Two operating public drinking water supply wells identified as N198 and N199 are about 2 miles to the northeast of the site. The NC DOH provided NYS DOH with water quality information on these wells for routine sampling between 1950 to 1991. Data were provided for selected, VOCs, metals, and miscellaneous indicator parameters for landfill leachate. Routine sampling did not include analysis for VOCs until 1977; however, to date, VOC contamination has not been detected. No metals are at levels above the NYS DOH drinking water standards.
In preparing this public health assessment, NYS DOH relied on the information provided in the referenced documents and assumed that adequate quality control measures were followed with regard to chain of custody, laboratory procedures, and data reporting. All documents that were prepared as part of the OU-1 RI/FS followed US EPA and NYS DEC QA/QC protocol.
According to the data tables included in the RI for subsurface soil analysis, a single trip blank was analyzed on one occasion for VOCs only. Therefore, limited quality control information is available for this medium and any VOCs found in the soil samples must be attributed to the landfill.
One potential hazard associated with the Syosset Landfill site involves the presence of methane in landfill gas. Methane can migrate through porous media as soil gas and enter confined building spaces (basements) through crawl spaces, plumbing holes, and other floor holes (e.g., sumps) and foundation cracks. The potential for methane to collect in a confined space is of concern as this condition may result in a flammable/explosive atmosphere and hence be a safety problem. Various measures have been taken to prevent methane migration into structures near the landfill.
To identify facilities that could contribute to groundwater, soil or air contamination in the area around the Syosset Landfill and/or create health threats unrelated to the site, NYS DOH searched the Toxic Chemical Release Inventory (TRI) data for 1990. The TRI is developed by the US EPA from the chemical release (air, water, and soil) information provided by certain industries.
NYS DOH uses a simple mathematical model to estimate if potential contaminant concentrations resulting from air emissions at a TRI reporting facility may be contributing to community (receptor population) exposures to contaminants at a site. This model uses information about the facility location (distance from the exposed population) and annual air emission data to calculate the radial distance from the facility at which contaminant concentrations in ambient air have been diluted to 1 microgram per cubic meter of air (mcg/m3). NYS DOH then evaluates what portion, if any, of the population living within this distance from the manufacturing facility may also be exposed to contaminants originating at the site.
A search of the 1990 TRI identified eight industrial facilities located within a 2.5 mile radius of the Syosset Landfill site. These facilities are Fiat Products, Permagile Industries, Contemporary Packaging Corp., Romac Electronics Inc., American Casting and Manufacturing Corp., Multiwire/EED/Division Kollmorgen, Metco Inc., and Loral Fairchild Systems. None of the facilities reported discharges to water or soil. Based on TRI data and air emissions modeling, results of the screening evaluation indicate that none of the facilities could affect ambient air near the Syosset Landfill site at levels exceeding a screening criterion of 1 mcg/m3. Consequently, emissions from these facilities would not be expected to pose an additional health risk of concern to the population near the site.
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 are 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.
No completed exposure pathways have been identified for this site.
Groundwater Exposure Pathways
Groundwater is contained in two water producing aquifers at the site. The two aquifers are hydraulically connected. The shallow aquifer, which is referred to as the Upper Glacial aquifer, extends from the surface to a depth of about 50 to 100 feet under the site and consists of coarse sand and gravel. The Upper Glacial aquifer is only partially saturated near the site. Unexcavated portions of this formation are found toward the boundaries of the site and beneath the landfill. Groundwater in this aquifer flows primarily in a northeasterly direction. Groundwater contamination in this aquifer has been detected on-site.
The deeper aquifer, which is referred to as the Magothy aquifer, extends from the bottom of the Upper Glacial aquifer to about 500 feet beneath the site and consists of fine sands often containing thin, discontinuous layers of silt and clay. Groundwater flow in this aquifer is also in a northeasterly direction. Groundwater contamination in this aquifer has been detected on-site. Cover soils at the site are sandy and infiltration is generally rapid through the shallow aquifer which the landfill is placed, downwards to the Magothy aquifer. The uncapped landfill, therefore, is a continuing source of contamination to the Magothy aquifer. The aquifer system underlying all of Long Island has been designated as a sole source aquifer since no other source of drinking water is available. The Magothy aquifer is the principal source of water for public and industrial use. Site remediation is on-going and once the landfill is capped, it will no longer be a source of contamination.
Groundwater contamination has been detected on-site in the Upper Glacial aquifer and in the shallow portion of the Magothy aquifer. Contaminants which have entered the groundwater beneath the site could be transported with the groundwater flow system towards downgradient public supply wells. The Jericho Water District public supply well (N4133), downgradient of the site was closed in 1974 due to taste and odor problems. Ammonia-nitrogen, a typical leachate indicator of municipal waste decomposition, was detected in this well. The extent of contamination cannot be fully evaluated due to the limited water quality information generated during operation of this well. For example, the methodology for the detection of VOCs was not in place until the late 1970's.
All public supply wells have been and are tested quarterly for over 70 VOCs as required by NC DOH since 1988. If any public supply well was to become contaminated, the current testing requirements would alert officials long before drinking water standards were exceeded. Prior to 1988 (1977 through 1987), all public supply wells were required to be tested annually for VOCs (about 10 - 30), including volatile aromatics. Metals have been tested for all public supply wells annually for more than 15 years (lead, barium, sodium and arsenic) or were tested for as part of the NC DOH's Priority Pollutant study (antimony and thallium). All of these compounds and others will also be tested routinely beginning in January 1993.
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. If site-related contaminants migrate to the active, downgradient public drinking water supply wells, the routine monitoring that is mandated by New York State will detect contamination. If contamination is detected, controls will be implemented to cease distribution thereby eliminating the potential for exposure to occur via this pathway.
Ambient Air/Soil Gas Pathways
Past, current, and future exposure pathways are possible from contamination of the ambient air on-site and at residential areas bordering the site. Populations at risk of exposure to contaminated ambient air via inhalation include: workers at the Town of Oyster Bay-Department of Public Works and animal shelter facilities; children, faculty, and staff at the South Grove Elementary School; employees of businesses near the landfill; and residents of the surrounding community.
Landfill gases generated from the degradation of buried wastes have migrated upward through the clean fill covering the Syosset Landfill. The major components of landfill gas are carbon dioxide and methane, with lesser amounts of oxygen, nitrogen, hydrogen sulfide, and trace amounts of VOCs.
On-site soil gas contains methane and VOCs which, based on physical properties, can volatilize through surface soils into the atmosphere. Once these contaminants are emitted from the soil, they are transported by wind to potential receptor points. The dominant wind directions at the site are out of the west, northwest, and north. Contaminants released to ambient air (breathing zone) will likely be dispersed and diluted at unconfined on-site and off-site areas.
Site contaminants could 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 and off-site buildings.
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. Available information indicates that on-site buildings were tested once in 1983 for methane only, and none was detected. Monitoring of the on-site gas control system indicates that landfill gas does occasionally migrate to the school side of the trench. Recent soil gas testing has not been performed at off-site locations; however, in 1981 soil gas testing on South Grove School property found explosive levels of methane. Subsequent soil gas sampling in 1981 and 1982 did not find methane in the soil on school property. Methane gas detectors in the school buildings have not detected gas above background levels to date.
The air study performed by the NC DOH in June/July 1991 was limited in scope and is not adequate to fully characterize the soil gas/ambient air pathway. Currently, the OU-2 RI/FS is on-going and will address off-site migration of landfill gases.
Surface Water/Sediment Exposure Pathways
This human exposure pathway has been eliminated from further discussion in this public health assessment since there are no surface waters adjacent to the site.
Soil Exposure Pathways
Based on past and current on-site conditions and controls, this human exposure pathway has been eliminated from further discussion in this public health assessment. Exposure to site-related contaminants in the surface soil is not expected to occur as the upper fill dirt is "clean" fill, brought in from off-site.
Exposure to contaminated subsurface soils will not occur unless subsequent on-site excavation of soils is conducted. Future remedial activities will include minimal, if any disturbance, of subsurface soils. Future excavation of on-site soils could exposed workers to contaminants via several routes including ingestion, inhalation and skin contact. Future exposure to site workers would be minimized if site workers follow appropriate guidelines.
On-site soil gas and groundwater are contaminated with VOCs and metals at levels of concern for potential human exposure pathways (see Appendix B, Tables 1, 2 and 4). Contaminants selected for further evaluation are identified with an asterisk (*) in the appropriate tables. An assessment of the toxicological implications of the potential human exposure pathways of concern is presented below:
1. Potential inhalation exposure to volatile organic compounds in air due to migration of soil gas into nearby homes and buildings.
Potential human exposure to methane and VOCs from off-site migration of landfill gas through air and soil may be occurring and/or may have occurred in the past. Adequate data are not available to assess the toxicological implications of this potential exposure pathway. There are some data to suggest that VOCs present in landfill gas could pose a public health threat at the highest levels detected (Appendix B, Tables 1 and 2). The potential health risks from exposure to these chemicals are discussed below. In addition, limited data on soil gas generation indicate that the off-site methane levels could pose a public health threat. One public health threat from methane generation is the potential for explosive levels of methane to accumulate in closed buildings and hence be a safety problem. Methane detectors in school buildings have not detected gas above background levels to date. Another public health threat is that toxic gases, such as vinyl chloride or other volatile chlorinated hydrocarbons, tend to be carried with methane. These chemicals can pose risks of adverse health effects if nearby residents are exposed. These risks are in addition to the effects that can be caused by large amounts of methane displacing oxygen in the air. Individuals who continue to breathe high levels of methane may become dizzy, experience difficulty in breathing or loose consciousness due to lack of oxygen (Sax, 1979).
Volatile Organic Compound Contaminants
Benzene and vinyl chloride are known human carcinogens (ATSDR, 1991a; 1992a). Methylene chloride, chloroform, 1,1-dichloroethene, 1,4-dichlorobenzene, bromodichloromethane, trichloroethene and tetrachloroethene have caused cancer in laboratory animals exposed to high levels over their lifetimes (ATSDR, 1989a,b; 1990a; 1991b,c,d,g; 1992b). Chemicals that cause cancer in laboratory animals may also increase the risk of cancer in humans exposed to lower levels over long periods. Whether these chemicals cause cancer in humans is not known.
The VOCs listed as contaminants selected for further evaluation in Appendix B, Tables 1 and 2 also produce several noncarcinogenic toxicities (primarily liver, kidney and nervous system effects) at high concentrations (ATSDR, 1989a,b,c,d,e; 1990a,b,c; 1991b,c,d; 1992a,b). Inhalation of ethylbenzene and vinyl chloride has been associated with adverse reproductive outcomes in animals (ATSDR, 1989c; 1992a). Exposure to benzene has been associated with damage to the blood cell-forming tissues and the immune system (ATSDR, 1991a). 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.
2. Potential ingestion, dermal and inhalation exposure to contaminants in drinking water from contaminant plume migration.
Currently groundwater in the contaminated aquifer is not used as a source of drinking water or other domestic purposes. However, residents are concerned about potential contamination of nearby drinking water supply wells. As indicated in Appendix B, Table 4, on-site groundwater is contaminated with volatile organic chemicals and metals at concentrations that exceed comparison values. Routine monitoring of public water supply wells minimizes the potential for exposures to occur.
Volatile and Semi-Volatile Organic Compound Contaminants
The toxicological properties associated with exposure to trichloroethene, tetrachloroethene, and vinyl chloride, have already been discussed. Chronic exposure to these contaminants at the highest concentrations found in on-site groundwater could pose a low increased cancer risk. In addition, chlorobenzene and 1,2-dichloroethene can cause nervous system, liver and kidney damage. Although the risks of noncarcinogenic effects from potential exposures aren't completely understood, the existing data suggest that they would be minimal from exposure to each of these five contaminants at the highest levels found in on-site groundwater.
Exposure to antimony can damage the blood cell-forming tissues, heart and liver (ATSDR, 1990e). Ingestion of arsenic can cause impaired nerve function, damage the skin and blood cell-forming tissues, and has been associated with skin cancer in humans (ATSDR, 1992c). Chronic exposure to elevated lead levels is predominantly associated with neurological and hematological effects (ATSDR, 1991e). The developing fetus and young children are particularly sensitive to lead-induced neurological effects. Exposure to elevated thallium levels has been associated with gastrointestinal irritation and heart and liver damage (ATSDR, 1990d). Ingestion of barium may cause cardiovascular effects, including increased blood pressure, damage to heart muscle and changes in heart rhythm, and has also been associated with kidney, neurological and gastrointestinal effects (ATSDR, 1991f). Exposure to elevated levels of zinc can cause gastric disturbances and effects on the immune system and blood (ATSDR, 1989g). Water containing more than 20,000 micrograms per liter (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 restricted diets. The level of iron in on-site groundwater is over 600 times the level at which the aesthetic quality of drinking water begins to be affected (WHO, 1984). Exposure to drinking water contaminated with either arsenic, lead or thallium at the highest concentrations found in on-site groundwater could pose a high increased risk of adverse health effects.
NYS DOH has not evaluated health outcome data specific for the Syosset Landfill site or the Town of Oyster Bay. However, in 1990, NYS DOH reported on breast cancer incidence rates for small geographic areas of Nassau and Suffolk Counties for the years 1978-1987. The relationship between breast cancer incidence and contaminated drinking water wells and hazardous waste sites was also examined. Variations were seen in breast cancer incidence rates among small geographic areas in these counties. A relationship was observed between high breast cancer incidence and high levels of household income. No association was found between breast cancer incidence patterns and contaminated drinking water wells or hazardous waste sites.
We have addressed each of the community concerns about health as follows:
|1.||What is the potential for groundwater contamination resulting from the migration of landfill leachate?
Available data indicate that groundwater under the site is contaminated with volatile organic compounds and metals at levels above comparison values. Under existing site conditions, the landfill serves as a continuing source of contamination to the underlying aquifers. The extent of migration of a contaminated groundwater plume cannot be determined at this time since off-site groundwater has not been studied. However, the current on-site groundwater monitoring data do not indicate a significant VOC plume emanating from the site. Historical information suggests that landfill leachate has contaminated off-site groundwater that led to the closure of a downgradient public supply well in 1974. Two active downgradient public supply wells located about 2 miles from the site have been and continue to be routinely monitored and to date, have not been found to be contaminated.
|2.||What is the potential for landfill gas migration to residential areas and the South Grove Elementary School?
Soil gas testing indicates that landfill gas does occasionally migrate to the school side of the on-site gas control system. During the early 1980's, investigations confirmed the migration of landfill gas onto South Grove School property. Methane detectors installed within the school buildings have not detected gas above background levels to date.
Soil gas and ambient air has not been tested at any nearby residential areas. The potential exists for landfill gas to migrate from the landfill onto adjacent residential areas. Additional investigations are required to further evaluate this pathway.
|3.||What additional health risks will be posed during planned closure activities at the landfill?
The selected clean-up remedy for the site is expected to protect human health. The US EPA is required, for site cleanups in New York State, to meet all applicable State regulations, including public health and air quality regulations. Notwithstanding, the Syosset Board of Education have decided to temporarily close the South Grove Elementary School during the planned 30 month duration of the landfill capping. The Town of Oyster Bay has developed a Health and Safety Plan (HASP) for this site which will be followed during the on-site field investigations and during cap construction.