PUBLIC HEALTH ASSESSMENT
PORT WASHINGTON LANDFILL
NORTH HEMPSTEAD, NASSAU COUNTY, NEW YORK
The Port Washington Landfill is on the eastern portion of Manhasset Neck which borders Hempstead Harbor, Nassau County, New York. The community of Port Washington is west of the site. On-site and off-site contamination of groundwater and soil gas has been attributed to a section of this municipal landfill called L4. Principal contaminants are volatile organic compounds (gasoline components, dry-cleaning fluids, solvents) from industrial waste disposal at the site. A residential area is 100 feet west of the landfill. In the past, landfill soil gas had migrated westward into this residential neighborhood. People can be exposed to contaminated soil gas from the landfill, either through sub-surface migration into homes or through ambient air. The landfill soil gas plume may have migrated to as many as 20 homes and several minor explosions have been documented. The area is served by a public water supply system using groundwater wells. The closest public water supply well is 1,300 feet west of the landfill and was taken out of service after low levels of volatile organic compounds (VOCs) were detected in the water.
During the fall of 1990 operational problems at the then active disposal cell, called the L5 Field 3, led to the production of large amounts of hydrogen sulfide gas which migrated off-site. People in the community complained of odors and were concerned about short-term health effects. In March 1991 the Agency for Toxic Substances and Disease Registry (ATSDR) completed a health consultation in response to citizen concerns over the hydrogen sulfide emissions from the L5 portion of the Port Washington Landfill. The ATSDR concluded that the concentrations of hydrogen sulfide which were measured on- and off-site posed a potential health threat to on-site workers and sensitive individuals living next to the landfill. The ATSDR recommendations in the health consultation reiterated the need for the actions which have since been taken.
Based on the information reviewed, the Port Washington Landfill represented a public health hazard (see Appendix E for additional information) because of past exposures to site-related contamination in soil gas, groundwater and ambient air. The town installed active and passive gas venting systems to control the off-site migration of soil gas. The Nassau County Department of Health (NC DOH), the New York State Department of Health (NYS DOH) and the New York State Department of Environmental Conservation (NYS DEC) directed the Town of North Hempstead to perform remedial measures to reduce or eliminate hydrogen sulfide emissions. The Town of North Hempstead performed these measures by February 1991 and greatly reduced the emissions. The site currently poses a no apparent public health hazard.
The NYS DOH has made further recommendations to (1) control and monitor landfill gas emissions, (2) address the landfill's role as an on-going source of groundwater contamination and treat existing groundwater contamination, and (3) conduct additional health studies.
The data and information developed in the public health assessment for the Port Washington Landfill, North Hempstead, New York, have been reviewed by the ATSDR's Health Activities Recommendation Panel for appropriate follow-up with respect to health activities. The panel agreed that fact sheets and public meetings should continue to be used by county, state and federal agencies to provide health information. The panel also determined that a review of health statistics and education of local health professionals are needed. In addition, the panel determined that the site be considered by the NYS DOH for inclusion in the state VOC registry.
Public health actions have been taken and/or are planned. (1) The NYS DOH evaluated the cancer incidence in census tracts north and west of the Port Washington Landfill for the years 1978-1984. The 1987 study showed a significant excess of brain cancer among males in a small portion of the study area. (2) As a follow-up, the NYS DOH is conducting a study of cancer incidence near a number of landfills in New York State which are known to be generating landfill gases, including the Port Washington Landfill. (3) The NYS DOH and the NC DOH have provided, and will continue to provide information in response to residents' health concerns. (4) Landfill closure measures will be taken which will prevent on-site contact with contaminated media and reduce human exposure due to the migration of contaminants from the site. (5) The construction of a groundwater treatment facility is planned. (6) An operation and maintenance plan for the landfill gas withdrawal system will be developed. (7) The selected clean-up remedy for the site will include a long-term monitoring plan to determine the effectiveness of the remedy.
A. Site Description and History
The Port Washington Landfill is in the northwestern portion of Nassau County, New York, in the Town of North Hempstead (Figure 1). It is on the eastern portion of Manhasset Neck and is bordered to the east by Hempstead Harbor, to the south by the Seaview Industrial Park, to the west by the North Hempstead Country Club and a residential area which is part of the Port Washington community, and to the north by a gravel mine. The landfill is on a 139 acre lot, owned and operated by the Town of North Hempstead. The parcel contains two landfilled areas; L4 is a 53 acre inactive section and L5 consists of four 15- acre sections, three of which were closed and the other one was never used.
The "L4" section of the Port Washington Landfill was placed on the United States Environmental Protection Agency (US EPA) National Priorities List (NPL) in December 1982 because of contamination in the area. Planning for a remedial investigation/feasibility study (RI/FS) was started in 1984. The RI/FS report was completed in June of 1989. The Remedial Investigation is carried out to determine the nature and extent of contamination at the site. Remedial investigations follow preliminary site investigations conducted by Town, County, State and/or Federal agencies that verify hazardous wastes are present and that the wastes pose a significant threat to public health and the environment. The FS uses RI information to develop alternative remedial actions that will reduce or eliminate the threat to public health or the environment posed by the site.
Prior to the Town's purchase of the property, the site was a sand and gravel mining operation which began in the 1880's when sea water was used for washing the sand and gravel from steep banks. After the mining operation stopped, the All American Sand and Gravel Company used the site as a construction and demolition debris landfill. The land was purchased by the Town for a municipal landfill in 1973.
The initial design of the landfill called for placing a clay liner between the refuse and the native soil. In January 1974, a 20 mil polyvinyl chloride (PVC) liner was installed which covered only 4 acres. Landfilling at L4 began in March 1974. About 260,000 tons per year of waste material were disposed at the L4 landfill. The fill consisted of residential, commercial, industrial, construction and demolition debris, and incinerator residue. Oil and gasoline saturated soil and asbestos were also disposed under New York State permit. Nearby residents have stated that drummed liquid waste were disposed at the site.
During 1975, leachate overflowed the liner and numerous odor complaints were made by residents in the surrounding communities. Leachate seeps occurred in areas of the landfill not protected by the liner. In March of 1976 a leachate treatment system was constructed consisting of a collection system, a receiving lagoon, and mechanical aerators. The effluent was chlorinated and then returned back to the L4 section through a series of sprinkler heads on the surface. Continuing problems with leachate due to the incomplete liner resulted in inorganic and organic contamination of on-site groundwater monitoring wells in 1977. In September 1977, the leachate collection system was connected to the Port Washington sewer system.
Expansion of the L4 section started in 1979 and eventually the liner covered a total of 29 acres. In addition to the PVC bottom liner, clay material was placed between waste material and the sand and gravel banks on the west side of the site.
During the winters of 1979, 1980 and 1981, small furnace area explosions occurred in homes 100-500 feet west of the landfill. In 1981, the NC DOH did extensive monitoring of the ambient, indoor, and soil gas and found methane levels that exceeded the lower explosive limits inside several homes. Volatile organic compounds (VOCs) in several of the affected homes ranged from 10.9 micrograms per cubic meter (mcg/m3) for 1,1,2-trichloroethane to 612 mcg/m3 for vinyl chloride. Soil gas sampling showed methane along the western boundary of L4 as well as extending onto the North Hempstead Country Club property to the southwest and to the Seaview Industrial Park to the south. As a result of the off-site methane migration, the Town installed, in several phases, active and inactive gas venting systems. Between July and October 1982, the US EPA monitored emissions from the passive vents at the landfill. Methane and other gases (vinyl chloride, toluene, tetrachloroethene, trans-1,2-dichloroethene, 1,1,1-trichloroethane and ethylbenzene) were being emitted from the landfill vents. Given the close proximity of residential areas to the site, the contaminants could migrate via ambient air into these areas west of the site.
In September 1980, VOCs (1,2-dichloropropane, 1,1,1-trichloroethane and tetrachloroethene) were detected in the Port Washington Water District's (PWWD) Southport Well, about 1,300 feet west of the L4 landfill. The initial finding of 107 micrograms per liter (mcg/L) for 1,2-dichloropropane was not confirmed by subsequent analysis in early March 1981. Samples collected in September 1981 showed 1,1,1-trichloroethane and tetrachloroethene at levels of 5 and 2 mcg/L, respectively, not exceeding NYS DOH or US EPA drinking water standards. The well was taken out of service in June 1981 on the basis of the detection of 33 mcg/L and 47 mcg/L of vinyl chloride in consecutive analyses. These results were later retracted by the reporting laboratory because improper instrumentation was used in the analyses. Additional samples collected in June and July 1981 and tested by two independent laboratories ruled out the presence of vinyl chloride; however, the follow-up samples were collected after the well pump was shut down.
Disposal operations ceased at the L4 landfill in July 1983. Since then, disposal activities were carried out at the adjacent L5 portion of the Town landfill. The current cell within the L5 landfill began operation in December 1989. This cell (Field 3) received baled municipal wastes, raw sewage sludge, uncompacted commercial and municipal wastes and processed construction and demolition debris (containing gypsum products) until the cell was closed by order of the Nassau County Board of Health in January 1991.
Because of poor operation and an inadequate or inoperative leachate collection system, several million gallons of leachate accumulated within Field 3 and beginning in late summer and fall of 1990, Field 3 began emitting high levels of hydrogen sulfide, methane and, to a lesser extent, VOCs. Hydrogen sulfide air levels measured off-site exceeded 1 part per million (ppm) on several occasions. Under several consent orders and a summary abatement order with New York State, the Town installed a gas containment system which used the horizontal combustion unit operating at the L4 landfill. Hydrogen sulfide levels on and adjacent to Field 3 were significantly reduced by mid-February 1991. In March 1991 the ATSDR completed a Health Consultation in response to citizen concerns over the hydrogen sulfide emissions from the L5 portion of the landfill. The ATSDR concluded that the concentrations of hydrogen sulfide which were measured on- and off-site posed a potential health threat to on-site workers and sensitive individuals living next to the landfill. The ATSDR recommended the following actions which have since been taken:
The Record of Decision (ROD) presents the remedial action for an inactive hazardous waste site and documents the information and rationale used to arrive at the decision. A ROD was signed in September 1989 and includes the construction of a permanent landfill cap on the L4 section, extension of the existing gas venting system around the perimeter of the L4 section, up-grading the existing active gas venting system and pumping and treatment of contaminated groundwater. The US EPA and the Town of North Hempstead negotiated a Consent Decree for the Remedial Design, which was signed in September 1991. A significant portion of the project costs will be paid by the New York State 1986 Environmental Quality Bond Act which will reimburse the Town for three quarters of allowable expenses for investigations, design and construction. Current projections for the completion of the remedial construction is 1998.
B. Actions Implemented During the Public Health Assessment Process
In 1987, the NYS DOH evaluated the cancer incidence in census tracts north and west of the Port Washington Landfill for the years 1978-1984. The study showed a significant excess of brain cancer among males in a small portion of the study area. As a follow-up, the NYS DOH is conducting a study of cancer incidence near a number of landfills in New York State which are known to be generating landfill gases, including the Port Washington Landfill. The NYS DOH and the NC DOH have provided, and will continue to provide information in response to residents' health concerns. The NYS DOH assisted the NC DOH by reviewing hydrogen sulfide air monitoring data and providing technical assistance.
Staff of the NYS DOH and the NC DOH visited the site during February 1985 to collect information for the NYS DOH Human Exposure Potential Ranking Model. At that time, strong odors were noted. There appeared to be minimal disturbance of the L4 section. Additional visits were made to the site during 1989, 1990, 1991 and 1993, for evaluation of the L4 section, as well as the L5 Field 3. Air emissions from the site have the potential to impact residential areas to the west and north of the landfill, as well as the Seaview industrial/office park along the southern perimeter of the landfill. Prevailing winds are either from the northwest or southwest. Northwest winds tend to funnel emissions from the landfill to the south into the Roslyn Harbor area. There are several children's camps/day schools several thousand feet to the south of the site. During the 1991 visit, the Town had not yet constructed a gas containment system to control hydrogen sulfide emissions from the L5 Field 3 cell. Mr. Lloyd Wilson of the NYS DOH and NYS DEC staff visited the site in June 1993. During the 1993 site visit, the L5 field 3 cell gas containment system was operating and no odors were detected either on-site or off-site. Also, no odors were present at the L4 section. Construction and monitoring activities associated with further remediation of the L4 section were observed during the 1993 site visit. Land use patterns are unchanged. There is an inactive gravel mine located directly to the north. To the east and northeast are public areas consisting of a bathing beach and Hempstead Harbor. Access to the landfill is controlled by a manned gate located on West Shore Road. The landfill is completely fenced.
D. Demographics, Land Use and Natural Resource Use
Land use in the areas surrounding the Port Washington landfill (L4) is varied (Figure 1). Northwest of the site, single family homes predominate. A residential development is located 50 feet from the western edge of the landfill. The closest residence to the west is about 100 feet from the site perimeter. The South Salem Elementary School is about 700 feet northwest of the landfill. An industrial park/commercial office development, the Seaview properties, is along the southern boundary of the landfill. To the north is a gravel mine. East of the site is the active L5 section of the landfill and further east is Hempstead Harbor. Directly west and southwest is the North Hempstead Country Club (golf course). The golf course has several wells used for lawn irrigation. Bar Beach, a public beach, is about one mile north of the eastern edge of the site on Hempstead Harbor. In addition to swimming, Hempstead Harbor is used for fishing and boating. It is not known to what extent shellfish are harvested from Hempstead Harbor. Residential areas are further to the south and along Shore Road. To the east, across Hempstead Harbor, are the residential communities of Roslyn Harbor and Glenwood Landing.
The NYS DOH estimated, from the 1990 Census, 7,856 people live within 1 mile of the Port Washington Landfill. The population within 1 mile of the site is 90.4 percent white, 0.8 percent of the African-American and 8.8 percent of other races. The site is within census tract 3014.00, in which 7.3 percent of the population is under 5 years of age, 17.4 percent is 5-19 years of age, 61.2 percent is 20-64 years of age and 14.1 percent is 65 years or older. The median household income in 1989 for this census tract was $79,901 with 2.4 percent of the families with income below the poverty level.
Beneath the landfill the Upper Glacial aquifer represents the uppermost water-bearing zone. The Magothy aquifer immediately underlies the Upper Glacial, with the Lloyd aquifer below separated from the Magothy by the Raritan aquitard. The Lloyd aquifer is the assumed bottom of the groundwater flow system because it overlies the bedrock. To the north, the Magothy, Raritan, and Lloyd have been replaced by the Port Washington Confining Unit and Aquifer. All of the aquifers described above are utilized locally for public water supplies.
The Upper Glacial aquifer, which generally flows from west to east beneath the landfill, carries water from the crown of the peninsula to Hempstead Harbor (an extension of Long Island Sound). The Magothy aquifer, which has similar flow characteristics, also discharges into Hempstead Harbor. The Lloyd aquifer is insulated from the local surface water bodies by the Raritan clay so that waters contained in this unit can migrate beneath Hempstead Harbor and Manhasset Harbor. According to the United States Geological Survey (USGS) (1987), the waters in the Lloyd Aquifer flow from east to west beneath the landfill discharging regionally into Manhasset Harbor and Long Island Sound. The Port Washington aquifer also has a regional flow component which allows for some water to flow beneath the water bodies bordering the peninsula.
The most significant users of groundwater in the area are the Port Washington Water District (PWWD) and the North Hempstead Country Club (NHCC). Several PWWD production wells are potentially affected by Landfill operations including the Southport, Stonytown, and Hewlett wells, as well as the Bar Beach Road well to the north of the site. Additionally, the NHCC has two irrigation wells along Port Washington Boulevard. There are no known private drinking water wells in the area.
The Southport well is 1,300 feet due west and hydraulically upgradient from the Port Washington landfill. It was constructed in 1954 and was utilized for public water supplies until June 12, 1981. The PWWD pumping records indicate that the cone of influence which was created when the Southport Well was pumping, reached eastward towards the landfill and intercepted groundwater from beneath the site. The Stonytown well was constructed 3,000 feet southwest and hydraulically upgradient from the landfill and was brought on line to replace the lost yield caused by the closing of existing district wells. However, the annual pumping rate at this location was reduced in 1982 to limit its cone of influence as a safeguard against possible contamination migrating to the well from the Port Washington landfill. Subsequently, in 1987 a permit from the NYS DEC was issued authorizing increased annual pumpage for the Stonytown well; however, water level and water quality monitoring requirements were also increased as an additional safeguard.
Throughout this time period, irrigation pumping has continued on the NHCC grounds. Withdrawals have been estimated to be as high as 1,000 gallons per minute during the summer months. This groundwater extraction may have significant impacts on the groundwater flow field beneath the landfill, especially given the proximity of the local water supply pumping.
The NYS DOH maintains several health outcome data bases which could be used to generate site specific data, if warranted. These data bases include the cancer registry, the congenital malformations registry, the heavy metals registry, the occupational lung disease registry, vital records (birth and death certificates) and hospital discharge information.
The NYS DOH conducted a study of cancer incidence in census tracts 3010p and 3014 in Port Washington for the years 1973 to 1984.
The NC DOH has been maintaining odor complaint records related to recent hydrogen sulfide emissions from the L5 Field 3 landfill, as well as odor complaints of a general nature, not specifically related to the Port Washington Landfill.
Since 1974 the community has expressed concerns that contaminants in the soil vapor and ambient air are affecting the health of those residents living near the landfill.
Since 1991, a series of public meetings were held with the community to address their concerns over severe odor problems and air emissions from the L5 section of the landfill and remediation of the L4 section. Public concerns over possible health effects from acute and long-term exposure to hydrogen sulfide were raised. In addition, there was concern over the ability of local and state officials to deal effectively with the problems. The most recent public meeting was in July 1993.
On May 2, 1994, the NYS DOH sent copies of the public health assessment for the Port Washington Landfill to all known interested parties, requesting concerns and comments on the report by June 9, 1994. The NYS DOH was alerted to additional community concerns about groundwater contamination posing a threat to the public and environment and about the potential contamination of Hempstead Harbor. The responses to public comments are in Appendix D.
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