PUBLIC HEALTH ASSESSMENT
SOUTH WEYMOUTH NAVAL AIR STATION
SOUTH WEYMOUTH, NORFOLK COUNTY, MASSACHUSETTS
South Weymouth Naval Air Station (SWNAS) is located in eastern Massachusetts, 15 miles south of downtown Boston, in the towns of Abington, Rockland, and Weymouth. SWNAS also borders the town of Hingham to the northeast. Established in 1941, past operations at the site have included aviation training, aircraft support, administrative coordination and logistic support, and lighter-than-air (blimp) operations. SWNAS was closed on September 30, 1997, and will be maintained by a caretaker office (operated by the Navy) until it is turned over to the surrounding communities for reuse. Land reuse will be managed by the South Shore Tri-Town Development Corporation (formerly the SWNAS Planning Committee), consisting of representatives of Abington, Rockland, and Weymouth.
Beginning approximately 10 years ago, the Navy undertook a series of investigations at SWNAS to identify potential areas of concern. The potential areas of concern identified by the Navy are divided into several groups: Installation Restoration Program (IRP) sites (7), Massachusetts Contingency Plan (MCP) sites (30), and sites identified by the Environmental Baseline Survey (EBS) (104--these include some MCP sites). In addition, there are eight potential areas of concern at the United States Coast Guard (USCG) Buoy Depot located on the SWNAS property. The Agency for Toxic Substances and Disease Registry (ATSDR) conducted site visits in 1994, 1996, 1997, and 1998 and examined the site for potential exposure pathways. ATSDR identified three pathways through which people may be exposed to site-related contaminants: 1) exposure to contaminated groundwater, 2) exposure to contaminated surface water and sediment, and 3) exposure to contaminated soil. The evaluation of these pathways is the focus of this Public Health Assessment (PHA). ATSDR evaluated each group of sites at SWNAS separately:
- MCP sites. ATSDR evaluated data on the MCP sites and determined that no apparent public health hazards are associated with these sites. Appendix A summarizes conditions and evaluates public health hazards for the MCP sites.
- USCG sites. ATSDR evaluated data on the USCG sites and determined that no apparent public health hazards are associated with these sites. Appendix B summarizes conditions and evaluates public health hazards for the USCG sites.
- EBS and IRP sites. ATSDR reviewed the results of the Phase I EBS and IRP investigations to determine whether any exposures associated with these sites pose a public health hazard. These sites pose no apparent public health hazard. This PHA deals mostly with data from the Phase I Remedial Investigation (RI) of the IRP sites and background locations. Pathway analyses based on these data are summarized below.
The Navy sampled groundwater at the site perimeter and IRP sites during RI investigations. The perimeter sampling was conducted to gain an understanding of what contaminants may be flowing on-site from off-site sources and to determine the concentrations of naturally occurring contaminants, such as metals. The sampling detected elevated levels of some metals and pesticides. Currently, no one is exposed to on-site groundwater. The surrounding communities may opt to use groundwater from the property in the future, however, depending on the quality and potential yield of the aquifer. Municipal drinking water, which must meet federal and state safe drinking water regulations, is supplied to SWNAS and surrounding areas.
The U.S. Environmental Protection Agency estimated that there are at least 85 private drinking water wells within a 4-mile radius of the site that could potentially be affected by groundwater contamination from SWNAS. A record search of private wells in the area has identified 53 active private wells in close proximity to the site. Of these, 8 are used for drinking water, 35 are used for non-drinking purposes, such as irrigation, and the uses of the remaining 10 private wells are unknown. Although no off-site monitoring wells are available, there is no evidence of contaminated groundwater migrating off site. Sampling at perimeter wells detected only metals, which are naturally occurring in groundwater. In addition, the highest metal concentrations were found in wells where the flow of groundwater is toward the site from surrounding areas. The Navy is conducting further groundwater investigations to better define groundwater flow and contaminant movement.
Contaminated groundwater on site does not pose a past or current public health hazard because no one is known to ingest this water. On-site groundwater is unlikely to pose a public health hazard in the future. Further investigation of water quality and potential yield will be done to determine the safety and adequacy of on-site groundwater as a drinking water source prior to future use. Off-site groundwater poses no apparent public health hazard. If future data indicate that contaminants are migrating into off-site groundwater at concentrations that exceed ATSDR health-based comparison values, then the potential for exposure to contaminants in private wells will be further assessed.
Surface Water and Sediment
As part of the RI, the Navy also sampled surface water and sediment at perimeter locations and IRP sites. Sampling detected elevated levels of metals, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls, and pesticides in some locations. In the absence of surface water and sediment comparison values, ATSDR compared surface water data to drinking water comparison values and sediment to soil comparison values. These comparison values assume daily exposure. Exposure to surface water and sediments both on site (to SWNAS residents or trespassers) and off site (to recreational users) are likely to be less frequent and of shorter duration than assumed by the comparison values. Surface water and sediment contaminant levels also are not high enough to pose a health hazard through likely exposures. In addition, the Navy plans to conduct remedial actions, as necessary, to prevent exposures after redevelopment.
Exposure to on-site and off-site surface water and sediment through recreational use does not present an apparent past or current public health hazard because any exposures are limited and contaminant concentrations are low. Future exposures to surface water and sediment are not expected to pose a public health hazard because remedial actions will prevent exposures.
The Old Swamp River runs through the eastern portion of SWNAS and feeds a downstream pond that currently provides approximately 10% of Weymouth's municipal water supply. Historically, this pond may have contributed up to 20% of the town's water. Antimony was detected in surface water above its comparison value in one upstream sample from Old Swamp River. Manganese was detected in surface water slightly above its comparison value in upstream and downstream samples. No off-site surface water samples have been taken from Old Swamp River. The Weymouth Department of Public Works regularly samples its water for organic contaminants and many metals but does not analyze its water for antimony or some of the other metals that have been detected at SWNAS.
Based on the overall lack of contamination detected in surface water from Old Swamp River, and given that the river supplies a relatively small percentage of Weymouth's total water supply, ingestion of drinking water from the Old Swamp River does not present an apparent public health hazard. Because surface water samples did contain antimony and manganese above comparison values and the Weymouth Department of Public Works does not sample for these metals, additional sampling from Old Swamp River is planned under the Phase II EBS and Phase II RI.
In 1996, as part of the RI, the Navy sampled surface and subsurface soil at perimeter locations and IRP sites. The sampling detected metals, PAHs, pesticides, and dioxins at some sites. Prior to closure in 1997, site access was limited by security patrols, perimeter fences, and a guard house. Although trespassing has reportedly increased since the site was closed and regular surveillance and maintenance of the perimeter fence was discontinued, access to the site is still relatively limited. Sites with contaminated soil are not near site residences and are unlikely to be used frequently for recreation. In addition, vegetation covers the contaminated soil in most areas, and any exposures to soil by site residents or trespassers are likely to be infrequent and of short duration. The soil contaminant levels detected are not expected to present public health hazards through the likely exposures.
Surface soil and subsurface soil do not present a past or current public health hazard because access is limited and contaminant concentrations are low. The types of future land use and/or remediation activities at the site are expected to reduce the potential for future exposures to surface and subsurface soil.
South Weymouth Naval Air Station (SWNAS) is located in eastern Massachusetts, 15 miles south of downtown Boston, 6 miles from the Atlantic coast, 7 miles south of Hingham Bay, and 11 miles west of Cape Cod Bay. The site is located in the towns of Abington, Rockland, and Weymouth, which are suburban areas with residential, industrial, and commercial land. SWNAS also borders the town of Hingham to the northeast (Figure 1). SWNAS was closed on September 30, 1997, and is now maintained by a caretaker office operated by the Navy. Through the South Shore Tri-Town Development Corporation (SSTTDC), formerly the SWNAS Planning Committee, the towns of Abington, Rockland, and Weymouth are working together on a joint reuse plan for the site. Once completed, the plan will be submitted to the involved communities for public vote.
Noncontiguous sites controlled by SWNAS include Squantum Gardens, Naval Terrace, and Nomans Land Island. Squantum Gardens is a 15-acre parcel in the city of Quincy that provides naval housing. Naval Terrace is a 12-acre parcel in Quincy that also provides naval housing. Nomans Land Island is a 628-acre island located 2.7 miles south of Squibnocket Point on Martha's Vineyard, Massachusetts, that was used as a weapons training area for military aircraft. Once demolition and deactivation of unexploded surface ordnance is completed, the island may be transferred to the U.S. Fish and Wildlife Service (Papoulias, 1998). This Public Health Assessment (PHA) covers the air station (SWNAS), off-site housing facilities (Squantum Gardens and Naval Terrace), and the weapons training area (Nomans Land Island). The PHA also addresses the United States Coast Guard (USCG) Buoy Depot located at SWNAS (Figure 2).
SWNAS was built in 1941 and assigned to be a lighter-than-air facility to guard against the threat of German submarines in the North Atlantic. The facility originally consisted of a large marsh covering three townships (Weymouth, Abington, and Rockland) and abutting a fourth (Hingham). Construction included two runways, which were further expanded in the 1950s. During World War II (WWII), SWNAS constructed, maintained, and supported blimps including K-class airships conducting anti-submarine operations. During World War II, Squadron ZP-11 included 8 airships. After WWII, SWNAS was placed on a reduced complement status.
From the end of WWII until 1970, SWNAS provided support for carrier-based anti-submarine warfare and transport units. In 1970, the anti-submarine warfare and transport units were either deactivated or transferred off site. In 1973, Helicopter Anti-Submarine Squadron 92 (VP-92) was commissioned and stationed at SWNAS. That same year, the Marine Air Reserve Training Detachment and a Marine Air Reserve Group were stationed at SWNAS.
In 1971, the Navy leased a 5.5-acre parcel along the western site boundary to the USCG for use as a buoy maintenance depot (HRP, 1998a). Although this site is still actively used for buoy maintenance, USCG recently requested a transfer of the property, and is working with the Navy and the U.S. Environmental Protection Agency (EPA) to complete this transfer.
During Operation Desert Shield/Storm in 1991, SWNAS provided support for both domestic locations and overseas commands. The most recent mission of SWNAS was to train all assigned units for upcoming mobilization assignments; to provide administrative coordination and logistic support to the Marine Air Reserve Training Detachment; to perform other functions as directed by the Chief of Naval Operations; and to administer the Naval Reserve Program (EPA, 1997).
In 1995, the Department of Defense's (DOD) Base Realignment and Closure Commission accepted the Navy's recommendation to close SWNAS. All operations--except those at the USCG facility--ceased and SWNAS closed on September 30, 1997. During active operations from 1941 through 1997, various aircrafts were stationed at SWNAS, including blimps, piston-engine airplanes, turbo-propeller patrol airplanes, fighter jets, and helicopters (Papoulias, 1999).
Squantum Gardens and Naval Terrace were housing units of the Squantum Naval Air Station (SNAS), located on the Squantum peninsula in Quincy and operated by the Navy for Naval and Marine Air Reserve activities. The Navy acquired the 630-acre SNAS site in 1917 and established a seaplane base for training and patrol. SNAS was also used as a destroyer and submarine base until 1929. Structures at SNAS included barracks, office buildings, ammunition magazines, a torpedo maintenance shop and magazine, recreations areas, and quonset huts. The Victory Plant Shipyard, operated by the Bethlehem Steel Company, occupied a portion of SNAS. This shipyard built 35 destroyers between 1918 and 1920, but was later gutted by a fire and production ceased (U.S. Navy Patrol Squadrons, 1999; USACE, 1999). In 1923, SNAS was commissioned as the first Naval Reserve Air Base. SNAS was closed in 1953 and then recommissioned to conduct training of Naval and Marine Corps reservists. A defensive launch site for U.S. Army Nike-Ajax antiaircraft missiles was located at SNAS from 1955 to 1961 (Nike Sites, 1999). Over the next 30 years, the Navy sold portions of SNAS, eventually retaining only the Squantum Gardens and Naval Terrace housing units. The former Navy marina has been refurbished as a commercial marina that includes restaurants, shops, and office space. Squantum Gardens and Naval Terrace continue to be used as off-site housing facilities for Navy personnel. Contamination or unexploded ordnance was not reported during the construction of the marina, condominiums and other buildings (Holtham, 1999).
Nomans Land Island was privately owned and used for recreational and agricultural purposes until it was leased, with exclusive military access, by the Navy during WWII for use as a radar triangulation point for Buzzards Bay and Newport. For 5 years after the war, the Navy continued to use the island for weapons training. Then, in 1952, the Navy took title to the island by eminent domain. An unknown number of military personnel were housed on the island, with as many as 150 Seabees stationed there during war years.
In the early 1970s, local environmental groups petitioned the government to use Nomans Land Island as a migratory bird sanctuary. In 1975, the Department of the Interior signed a Joint Management Agreement with the Navy designating the eastern third of the island as a bird sanctuary while permitting continued use of the rest of the island as a target area. Weapons training at Nomans Land Island stopped with SWNAS closure, but other Navy training operations may still take place there on occasion (Papoulias, 1998). In 1982, the eastern third of the island was designated as a "no fire zone" to provide disturbance-free nesting conditions for migratory birds who nest in the island's diverse upland and wetland habitats. Nomans Land Island may be transferred to the U.S. Department of Fish and Wildlife in the future.
Contamination identified at SWNAS and SNAS resulted from past operations and activities, such as airplane operation and maintenance, as well as waste disposal and hazardous materials management practices. At Nomans Land Island, weapons training resulted in substantial amounts of live and inert ordnance, bullets, and spent bomb casings scattering its terrain.
In 1983, DOD initiated the Installation Restoration Program (IRP) at SWNAS. IRP investigations have identified seven sites as potential areas of concern (Figure 3). EPA placed SWNAS on the National Priorities List on May 31, 1994. As part of the IRP, DOD initiated a Community Relations Program, which includes an information repository for public review of IRP documents and the creation of a Restoration Advisory Board (RAB). The following studies have been conducted at SWNAS:
- Preliminary Assessment (PA). In 1988, the Navy conducted a PA, which consisted of a records search, interviews, and a site tour (Argonne, 1988). No samples were collected during the PA. The conclusions of the PA classified SWNAS as a "small quantity generator" of hazardous waste. The PA recommended dividing the site into five sites: West Gate Landfill (WGL), Rubble Disposal Area (RDA), Small Landfill (SL), Fire Fighting Training Area (FFTA), and Tile Leach Field (TLF).
- Site Investigation (SI). In 1991, the Navy conducted an SI (Baker, 1991). The SI included the five sites identified in the PA, plus three additional sites: Fuel Tank Farm (FTF), Sewage Treatment Plant (STP), and Abandoned Bladder Tank Fuel Storage Area (ABTFSA). The SI consisted of site walkovers, geophysical surveys, installation of 20 groundwater monitoring wells, and collection of soil, sediment, surface water, and groundwater samples. The data generated during the SI were intended only for "screening" purposes to identify sites for further study; they were not intended to delineate the extent of contamination or to characterize risk. The SI concluded that the TLF and STP required no further action, based on a lack of evidence that wastes were disposed of in these locations. Nonetheless, the Navy decided to include these two sites within the scope of the subsequent Remedial Investigation (RI), but required fewer monitoring wells and sampling locations for these sites. The SI recommended managing the FTF under the Massachusetts Contingency Plan (MCP) rather than the IRP because of the petroleum exclusion policy in the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). The FTF is evaluated in Appendix A with the other MCP sites.
- Phase I Environmental Baseline Survey (EBS). The Navy conducted the Phase I EBS in 1996 to assess the current environmental conditions of the SWNAS property before it is transferred or leased (Stone & Webster, 1996). The EBS included a site reconnaissance; a records review; interviews with facility users, occupants, and local residents; a review of aerial photographs; and a survey of the prior uses of the facilities. This EBS identified 104 areas of potential concern, including some MCP sites but no IRP sites.
- Phase I EBS: USCG Buoy Depot. USCG has undertaken a separate EBS for this facility. No samples were collected or analyzed for the Phase I EBS. The Final EBS report, completed in March 1998, listed eight potential areas of contamination and recommended sampling at six of these areas (Figure 4). Appendix B provides details regarding each of the eight areas. Results of the Phase I EBS served as a basis for sampling conducted under the Phase II EBS (HRP, 1998a).
- Phase II EBS: USCG Buoy Depot. In September 1998, USCG completed a Phase II EBS based on recommendations from the first phase. A limited number of groundwater and soil samples were collected and analyzed to assess the potential for site contamination from past operations (HRP, 1998b). Sampling results are presented in Appendix B.
- Phase I Remedial Investigation. The Navy conducted a Phase I RI in 1996 encompassing the seven IRP sites (Brown and Root, 1997). Based on the results of site investigations, the RI recommended cleanup goals and future actions dependent upon potential site reuse, which has not yet been finalized.
- Resource Conservation and Recovery Act (RCRA). SWNAS submitted a RCRA Part A Hazardous Waste Permit Application in August 1980 (Stone and Webster, 1996). Under RCRA, SWNAS is considered a large quantity generator because the site generates more than 1,000 kilograms per month of hazardous waste or over 1 kilogram per month of acutely hazardous waste. The RCRA permit requires SWNAS to determine if waste is hazardous, obtain an EPA Identification Number, and comply with record keeping requirements. Massachusetts Department of Environmental Protection (MADEP) regulations provide additional requirements for large quantity hazardous waste generators. The permit will be discontinued when site remediation is completed.
- National Pollution Discharge Elimination System (NPDES). SWNAS was issued a NPDES permit by EPA in 1975 (Stone and Webster, 1996). The permit requires the facility to inspect storm water discharges on a quarterly basis for oil and grease, settleable solids, suspended solids, and pH. Sampling is currently suspended because industrial activities at the site have ceased. The permit will be discontinued when site remediation is completed.
The following investigations and documents will be completed in the future:
- Phase II EBS. Sampling at SWNAS under the Phase II EBS was completed in winter 1999. The Phase II investigations included sampling at 52 of the 104 potential areas of concern identified in the Phase I EBS. Data from this sampling event are scheduled to be available for review in summer 2000 (Simenas, 1999).
- Phase II RI. The Phase II RI is scheduled to commence in spring 1999. Groundwater, surface water, sediment, surface soil, and animal tissue samples will be collected from the seven IRP sites and background locations. Data from this sampling event are scheduled to be available for review in spring 2000 (Simenas, 1999). The Agency for Toxic Substances and Disease Registry (ATSDR, 1999) reviewed the proposed sampling plan and provided the Navy with comments regarding the proposed groundwater sampling.
- Environmental Impact Statement (EIS). After a reuse plan has been agreed upon by the SSTTDC and ratified by the involved communities, an EIS will be required to determine what effects the proposed development and land usage might have on the local environment. The Navy, SSTTDC, and regulatory agencies will determine the types of investigations to be performed for the EIS. The Navy will prepare the EIS.
- Feasibility Study (FS). FSs will present and evaluate the various remediation strategies available for each IRP site. A FS for each site will be produced using data from the completed RI.
At full capacity, SWNAS supported a maximum staff of 3,750 people. Of these, 775 were military staff who resided at the site; 2,600 were selected reservists who resided at the site on weekends; and 375 were civilian employees (Barny, 1997). Currently, approximately 433 military staff and their families live on site. The housing office estimates that 133 of these residents are children. ATSDR used 1990 U.S. Census Data to compile demographic information for the area within a 1-mile radius of SWNAS. Information was gathered for the towns of Abington, Hingham, Rockland, and Weymouth. The population residing within 1 mile of the site is 22,121. Of these, 2,206 people are under the age of 6 while 2,952 people are over the age of 65. Figure 1 summarizes demographic information.
Squantum Gardens and Naval Terrace
Squantum Gardens and Naval Terrace are off-site housing facilities located approximately 10 miles from the air station. The eastern half of the Squantum peninsula has been developed with condominiums and restaurants. Squantum Gardens consists of seven multi-family units and one single-family house, with a total capacity of 52 families. Naval Terrace provides off-site housing in 24 duplex housing units for married personnel stationed at SWNAS. Housing units at Squantum Gardens and Naval Terrace were constructed in the 1950s and 1940s, respectively (Stone & Webster, 1996).
Nomans Land Island
Nomans Land Island has been vacant since the 1950s (Stone and Webster, 1996). During WWII, personnel were stationed on the island to maintain targets. Prior to 1943, when the Navy leased the property, ranchers and a small fishing community lived on the island.
SWNAS is located in a residential, suburban area approximately 15 miles south of Boston. No agricultural land is located on the site, nor is any land under lease to civilians or outside agencies for grazing or any other use (Stone and Webster, 1996). Historical sources indicate that the property was largely undeveloped prior to its acquisition by the Navy in 1941.
Currently, SWNAS is partially developed. Half of the site is forested, dominated by maple, oak, and pine trees; the other half has been developed for site activities. Wetlands exist along Old Swamp River, French's Stream, and Twin Ponds, which are two small ponds located east of French's Stream, near the site's southern boundary. In addition, two areas of open wetlands exist. Wetlands are also found in ditches that are heavily covered with fruit-producing shrubs that provide food and cover for wildlife.
During construction in 1941, low wetland areas were filled for the airfield, runways, taxiways, and related facilities. Other areas of the site were regraded and surface water was diverted through culverts and channels to the two major surface water bodies on site, French's Stream and Old Swamp River. Currently, surface water flows off the site via three outfalls (Stone and Webster, 1996). Outfall No. 1 handles the majority of storm water from the industrial and administrative areas of the site, as well as from the western part of the site. This outfall discharges into French's Stream in a marshy area just beyond the fenceline and south of Spruce Street. French's Stream itself is considered the second outfall at the point where the stream crosses the SWNAS property line. After leaving SWNAS, French's Stream passes briefly through Rockland and then into Abington. The eastern portion of the site discharges to Outfall No. 3, Old Swamp River. Old Swamp River flows from Rockland through SWNAS and Hingham before entering Weymouth and discharging into the southern area of Whitman's Pond, also called South Cove. The river's run from SWNAS to South Cove is approximately 2 miles. Since 1964, water from South Cove has served as Weymouth's secondary water supply and has been pumped on occasion to Great Pond (located approximately 0.25 mile west of SWNAS), which is the primary water supply for the town of Weymouth. Groundwater wells, which supply less than 20% of the water supply, also supplement the surface water supply system (MAPC, 1984).
The depth to shallow groundwater throughout the SWNAS site ranges from approximately zero to 10 feet below ground surface (bgs), with seasonal variation. At each of the site's seven IRP sites, shallow groundwater discharges to adjacent drainage channels, French's Stream, or Old Swamp River.
Squantum Gardens and Naval Terrace housing areas are located in an extensively developed section of Squantum, which is part of the city of Quincy. Quincy is located directly south of Boston on the Bay of Dorchester. One 1.6-acre wetland is located on the northern end of the Naval Terrace property (Stone and Webster, 1996).
Nomans Land Island is located in the Atlantic Ocean, approximately 2.7 miles south of Martha's Vineyard. The north shore of the island has a sand and gravel beach with a prominent sand spit. Cranberry bogs cover approximately 200 acres and shallow lakes cover approximately 40 acres of the island (Stone and Webster, 1996). The eastern third of the island is designated as a "no fire zone" to provide disturbance-free nesting conditions for migratory birds who nest in the island's diverse upland and wetland habitats. No trespassing signs are posted around the island and navigational maps designate the water surrounding the island as a Restricted Waterway. No docks are present for landing boats. The airspace above the island is restricted for military use (Foster Wheeler, 1998; Malewicz, 1999).
In preparing this PHA, ATSDR relied on the information provided in the referenced documents. ATSDR assumes that site documents were prepared with EPA and MADEP oversight and that adequate quality assurance and control measures were followed with chain-of-custody, laboratory procedures, and data reporting. The validity of the analyses and conclusions drawn in this document are dependent upon the availability and reliability of the referenced information.