PUBLIC HEALTH ASSESSMENT
SOUTH WEYMOUTH NAVAL AIR STATION
SOUTH WEYMOUTH, NORFOLK COUNTY, MASSACHUSETTS
In June 1994, ATSDR conducted a site visit to review available site-specific information, to visually inspect the IRP sites and other areas where hazardous substances have been released, and to identify any potential public health issues (ATSDR, 1994). ATSDR staff met with personnel from the Navy, MADEP, Massachusetts Department of Public Health (MADPH), and a local community member. ATSDR did not identify any immediate public health hazards. Based on known groundwater and surface water contamination at the site, however, ATSDR identified two public health issues on which to focus:
- Is on-site groundwater contamination currently migrating toward off-site private drinking water wells? Could it migrate in the future?
- Is on-site surface water contaminated? If so, does it pose a public health hazard to off-site residents who may come in contact with the contaminated medium?
ATSDR recommended that the Navy characterize the on-site groundwater contamination and, if the data indicate that contamination is moving off site, further assess the potential for public health hazards from use of private wells in the vicinity of SWNAS. ATSDR also recommended that, if on-site surface water samples contain contaminants, all surface water leaving the site should be sampled at the site's boundary to determine whether surface water contamination is at levels that pose a public health hazard (ATSDR, 1994).
ATSDR conducted additional site visits in 1996, 1997, and 1998 to meet with the Navy, EPA, MADEP, and community members. During these site visits, ATSDR discussed site activities and identified community concerns. In addition to groundwater and surface water issues previously identified, ATSDR also identified the following public health issue based on the site's closure and pending reuse:
- Is on-site soil contaminated? If so, does it pose a public health hazard to trespassers or to future residents or visitors?
In this section, ATSDR evaluates potential exposure pathways to determine whether people accessing or living near SWNAS could have been, are, or will be exposed to site-related contaminants via ingestion, dermal (skin) contact, or inhalation of vapors. Exposure pathways are considered "complete" when exposure to contaminated media occurs. To determine whether completed pathways pose a potential public health hazard, ATSDR compares contaminant concentrations to health-based comparison values. If contaminant concentrations are above comparison values, ATSDR further analyzes exposure variables (e.g., duration and frequency) and the toxicology of the contaminant. Figure 5 summarizes this exposure evaluation process.
Comparison values are chemical-specific concentrations derived for different media (e.g., groundwater or soil) to which people may be exposed. ATSDR health assessors use comparison values to select environmental contaminants of concern for further evaluation. Although chemical concentrations less than comparison values are unlikely to pose a health threat, chemical concentrations above comparison values do not necessarily represent a health threat. Further considerations include site-specific pathway analysis regarding potential for and extent of exposure. Comparison values used in this document include EPA's Maximum Contaminant Levels (MCLs) and ATSDR's Environmental Media Evaluation Guides (EMEGs), Reference Dose Media Evaluation Guides (RMEGs), and Cancer Risk Evaluation Guides (CREGs). MCLs are enforceable drinking water regulations developed to protect public health, but they also consider economic and technological factors. EMEGs, RMEGs, and CREGs are strictly health-based comparison values developed by ATSDR and are not enforceable. Comparison values are described in more detail in Appendix C.
Although the majority of this PHA deals with data from the IRP sites being addressed under CERCLA, ATSDR also evaluated MCP sites that are administered through MADEP and the potential areas of concern at the USCG Buoy Depot. The 27 MCP sites identified at SWNAS and the 3 MCP sites identified at Squantum Gardens consist mainly of small releases of petroleum products, which are excluded under CERCLA. At Squantum Gardens, no CERCLA sites have been identified based on information provided by the Navy, therefore, only the three identified MCP sites were evaluated by ATSDR. In addition, the U.S. Army Corps of Engineers determined that Squantum Gardens qualifies as a Formerly Used Defense Site and is eligible for funding under the Defense Environmental Restoration Program (USACE, 1999). Of the MCP sites identified at SWNAS and Squantum Gardens, two of the 30 sites had light non-aqueous phase liquid (LNAPL), also called free product, floating on groundwater. Two of the 30 sites had light non-aqueous phase liquid (LNAPL), also called free product, floating on groundwater. The majority of these sites, including those with LNAPL, were remediated quickly with MADEP oversite or are continuing to undergo remediation. Any past exposures would be expected to have been of short duration considering the rapid response time. Current and potential future exposures were prevented by completed remedial actions. At several locations, contamination remains in subsurface soil under the foundation of buildings. MADEP considers the potential for volitalization through the foundation into indoor air when evaluating and approving remedial actions. Therefore, future exposures to contaminants in indoor air is unlikely. Appendix A provides descriptions of the MCP sites, summarizes past activities, and describes future activities. Several MCP site locations are also included in Figure 3. ATSDR determined that the MCP sites do not pose a public health hazard, based on one or more of the following: 1) security measures effectively prevented past exposures and limit current exposures, 2) contaminant concentrations detected at the sites are too low to pose a public health hazard, and/or 3) affected areas have been or will be remediated.
Potential areas of contamination were identified at the USCG Buoy Depot during the Phase I EBS based on past reported releases, records review, and visual observations. No samples were collected during the Phase I EBS, however, site sampling was conducted under a Phase II EBS completed in September 1998. Methylene chloride, benzo(b)fluoranthene, benzo(k)fluoranthene, cadmium, and lead were detected in groundwater above comparison values. Methylene chloride is used in the laboratory analysis process and is a contaminant commonly introduced into samples by the laboratory. This is believed to be the source of methylene chloride in the groundwater samples. In addition, the method used to collect the groundwater samples also introduced a portion of soil to the sample. The concentrations of benzo(b)fluoranthene, benzo(k)fluoranthene, cadmium, and lead were likely from the soil in the sample rather than from these being dissolved in the groundwater. Actual groundwater concentrations would expected to be lower. Therefore, ATSDR determined that groundwater poses no apparent public health hazard. Two surface soil samples contained lead above its comparison values. Access restrictions limit public exposure to lead in soil. Therefore, soil exposure poses no apparent public health hazard. Appendix B provides descriptions of the potential areas of concern at the USCG Buoy Depot, summarizes past activities, presents sampling results, and describes future activities. USCG Buoy Station areas of concern are shown in Figure 4. Public health issues at the depot may need to be reevaluated after additional sampling is performed or a change in land use is planned.
ATSDR evaluated potential past, current, and future exposure pathways at SWNAS to determine if any public health hazards exist. ATSDR reviewed the Phase I EBS and draft Phase I RI to determine whether the Navy's sampling program was sufficient to identify any migration of site-related contamination to private drinking water wells and/or off-site surface water potentially used by area residents. In addition, ATSDR reviewed the sampling plans for the Phase II EBS and Phase II RI to determine whether these investigations address any data gaps from previous investigations. ATSDR also evaluated the potential for contaminated groundwater to be consumed by off-site residents by reviewing groundwater monitoring data and municipal drinking water monitoring data. ATSDR communicated with the boards of health of Abington, Hingham, Rockland, and Weymouth to assess private drinking water well usage adjacent to SWNAS.
It is important to note that environmental investigations at SWNAS are ongoing. In the future, if contamination is detected at levels that could pose a public health hazard and people are or could potentially be exposed, then ATSDR will evaluate the data and recommend appropriate public health actions. ATSDR identified the sites listed below as the ones associated with potentially completed exposure pathways (Table 1) and with contamination detected above health-based comparison values (Tables 2 through 11).
As reported in the Phase I EBS and draft Phase I RI, past operations at the site resulted in contamination of the following areas:
- Site One -- West Gate Landfill. The WGL covers an area of approximately 228,000 square feet and is located at the midpoint of the western border of SWNAS. From the 1940s until 1972, the WGL was an active landfill receiving incinerator ash from domestic waste. Medical wastes from a small on-site clinic may also have been disposed in this landfill. The landfill has been inactive since 1972 and has become overgrown with brush and trees. During the RI, the Navy sampled groundwater, leachate, surface water, sediment, surface soil, and subsurface soil. Metals, pesticides, polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs) were detected in various site media above ATSDR health-based comparison values.
- Site Two -- Rubble Disposal Area. The RDA covers an area of approximately 167,250 square feet and is located on the western bank of the Old Swamp River at the end of Runway 26. The RDA was created when the low, swampy area along the bank of the river was filled in with building debris from on-site sources and with fire debris from a 1978 fire that destroyed the former gymnasium/all-purpose building. Disposal at the RDA stopped in the mid-1980s. The Phase I EBS reports that hazardous waste, such as transformers, may have been disposed of at the RDA. During the RI, the Navy sampled groundwater, surface water, sediment, surface soil, and subsurface soil at the site. Metals, PAHs, PCBs, and volatile organic compounds (VOCs) were detected in various media at concentrations above ATSDR health-based comparison values.
- Site Three -- Small Landfill. The SL, located east of the Old Swamp River, covers approximately 34,700 square feet. During the mid-1980s, the SL was filled with concrete rubble and tree stumps. The Phase I EBS reports that the SL was not used as extensively as the WGL. The Navy sampled groundwater, surface soil, and subsurface soil during the RI. Metals and PAHs were detected in various media at concentrations above ATSDR health-based comparison values.
- Site Four -- Fire Fighting Training Area. The FFTA covers an area of approximately 166,190 square feet and is located south of Runway 8-26, adjacent to the drainage channel along Taxiway C. The channel passes underneath the FFTA via a drainage culvert. Fire fighting training occurred at the site from the mid-1950s until 1986. The training involved placing waste oil and other fuels in old vehicles and burning them. In 1988, the Navy installed concrete burn pits for igniting jet fuel during training exercises. Fire fighting training has since been discontinued. During the RI, the Navy sampled groundwater, surface water, sediment, and surface soil. Metals and PAHs were detected in various media at concentrations above ATSDR health-based comparison values.
- Site Five -- Tile Leach Field. The TLF covers an area of approximately 13,050 square feet and is located along a drainage ditch near the approach to Runway 8. Sanitary wastes from the lighter-than-air hanger were disposed of at the TLF from 1945 until 1956. The Phase I EBS reports that gasoline, fuels, and lubricants used in the maintenance of dirigibles may have been disposed of on site. The TLF also may have received battery acid wastes. During the RI, the Navy sampled groundwater, surface water, sediment, surface soil, and subsurface soil. Metals were detected in various media at concentrations above ATSDR health-based comparison values.
- Site Six -- Sewage Treatment Plant. The STP covers an area of approximately 40,000 square feet and is located in the northern portion of SWNAS. The STP operated from 1956 to 1978, at which time the site was connected to the municipal sewer system and the STP was decommissioned. While in operation, the STP discharged effluent to French's Stream. Limited soil and groundwater sampling took place in 1993 during the removal of two buried chlorine gas cylinders. During the RI, the Navy sampled groundwater, surface water, sediment, surface soil, and subsurface soil. Metals, PAHs, PCBs, and pesticides were detected in various media at concentrations above ATSDR health-based comparison values.
- Site Seven -- Abandoned Bladder Tank Fuel Storage Area. The ABTFSA covers an area of approximately 20,000 square feet and is located northwest of the Fire Protection Pump House. The ABTFSA was used to store aviation fuels so that jets could refuel on the taxiway immediately after landing, without returning to the hangar apron. The bladders were placed on sandy soil and surrounded by an earth berm. The site was used until 1987. During the RI, the Navy sampled groundwater, surface water, sediment, surface soil, and subsurface soil. Metals and PAHs were detected in various media at concentrations above ATSDR health-based comparison values.
- Background locations. Samples of groundwater, surface water, sediment, surface soil, and subsurface soil were collected at various locations to determine the background concentrations of contaminants at the site. Background is generally considered the concentrations of chemicals that occur naturally in site media. For example, metals are natural components of soil, but different types of soil throughout a region may contain metals at different concentrations. Six groundwater monitoring wells were installed along the perimeter of the site to capture groundwater flowing onto the site from surrounding neighborhoods. Surface water and sediment samples were collected in surface water bodies from upstream and downstream on-site locations. Soil samples were collected from various locations on the property. Contaminants detected in background samples may be the result of past operations at SWNAS or other sources, such as the fill material used to build the site, vehicle exhaust, regional pesticide spraying, or naturally high metal concentrations. Regardless of the potential sources, ATSDR evaluated contaminant concentrations detected in background samples against comparison values. PAHs, pesticides, and metals were detected in groundwater, surface water, sediment, and/or surface soil collected as background samples.
ATSDR identified the following three potential exposure pathways related to contamination at SWNAS:
- Ingestion of groundwater
- Ingestion of and dermal contact with surface water and sediment
- Ingestion of and dermal contact with soil
The following sections evaluate these potential exposure pathways in more detail. The sections consider gathered data and completed or planned remedial activities to determine whether the pathways present, under site-related conditions, a public health hazard. Table 1 lists the potential exposure pathways discussed in this section of the PHA.
ATSDR concluded that contaminants in groundwater pose no apparent public health hazard. The following information supports ATSDR's conclusion:
- Past activities at SWNAS resulted in groundwater contamination underlying the site. Sampling detected bis(2-ethylhexyl)phthalate, pesticides, and metals above comparison values (Tables 2 through 9).
- SWNAS has never operated drinking water supply wells at the site. No past or current exposures to on-site residents have occurred. If future site users decide to install drinking water supply wells, more investigations of water quality, potential yield, and potential health hazards will be required.
- Approximately 85 private properties within a 4 mile radius of SWNAS are thought to operate private water supply wells. Metals were detected in several perimeter wells, however, these wells are located in areas where groundwater is flowing from the surrounding area toward SWNAS. Metals are also a natural component of soil and are naturally occurring in groundwater. A small plume of tetrachloroethylene (PCE) exists in the central portion of SWNAS, near Building 81. A plume is an area of groundwater contamination that consists of contaminants released from the same source, such as a spilled drum or leaking underground storage tank (UST). Sampling indicates that this PCE plume is contained within the site boundaries. The Navy completed soil removal actions to remove the PCE source and is evaluating groundwater treatment options to prevent PCE migration. Because sampling data indicate that any contamination at SWNAS is contained within its boundaries and is not migrating off site, private wells surrounding SWNAS are not expected to be affected by this contamination.
- The Navy is conducting additional groundwater sampling under a Phase II EBS and a Phase II RI. The purpose of these studies is to further characterize groundwater in the aquifers underlying the site and potential migration pathways to prevent future exposures.
Hydrogeology and Groundwater Use
The geology of the SWNAS site is characterized by glacial deposits, typically consisting of glacial till and glaciofluvial (river) and glaciolacustrine (lake) deposits. These deposits comprise the overburden, 0 to 40-feet thick, that lies on top of the site's granite bedrock. In addition to these natural deposits, extensive filling has occurred at SWNAS; fill materials have consisted of silt, sand, gravel, cobbles, and--in some areas--debris.
Groundwater can be found within the glacial deposits and, reportedly, within the bedrock. Groundwater is generally encountered within 0 to 10 feet bgs. At each of the IRP sites, the Navy determined that shallow groundwater discharges to adjacent drainage channels, French's Stream, or Old Swamp River (Brown and Root, 1997). Groundwater at SWNAS generally flows into one of two major drainage basins: the Weymouth River Drainage Basin and the Southeastern Massachusetts Drainage Basin. Recent groundwater data indicate that the border between these two basins divides the SWNAS site in a northwest-to-southeast direction, so that property in the western portion of SWNAS drains to the southwest and discharges into French's Stream, while property in the eastern portion of SWNAS drains to the northeast into Old Swamp River. Groundwater underlying the drainage basin for Old Swamp River is referred to as the Swamp River Aquifer, the aquifer underlying the French's Stream drainage basin is not specifically named. Figure 6 shows the two drainage basins.
In the past and currently, groundwater underlying SWNAS has not been used as a drinking water supply. However, portions of SWNAS are located within the estimated boundaries of potentially productive aquifers (PPAs) as classified by the MADEP; two of the seven IRP sites are located within these medium-yield PPAs. The majority of the site lies over a non-potentially productive aquifer. The aquifer classification, however, is based solely on the original zoning of the area for industrial use by SWNAS, rather than on the aquifer's current water quality or potential yield. Closure of SWNAS and future changes in land use could lead to reclassification of the aquifer as a PPA and thus a potential drinking water source for surrounding communities. Any determination of the suitability of this aquifer to supply drinking water will require more extensive investigations of water quality and potential yield. Although no drinking water supplies are located within SWNAS boundaries, private wells have been identified at homes in surrounding residential neighborhoods. These wells may serve as drinking water supplies and/or for non-potable purposes, such as irrigation or industrial processing.
Nature and Extent of Contamination
During the RI, 49 groundwater monitoring wells were installed at the IRP sites. These monitoring well locations are shown in Figure 7. The Navy installed and sampled groundwater monitoring wells at the individual IRP sites to gain an understanding of groundwater flow directions, flow rates, and migration pathways. Most wells installed during the RI sampled only shallow groundwater at 3 to 20 feet bgs. Four wells located throughout the site sampled deeper groundwater at 20 to 38 feet bgs. Shallow groundwater wells were installed at each IRP site because contamination was released to surface soil or drainage channels. Therefore, shallow groundwater is likely affected by surface contamination first.
The Navy collected and analyzed 48 groundwater samples from the IRP sites. The groundwater beneath some areas of the site is contaminated with pesticides and metals above comparison values (Tables 2 through 8). One SVOC (bis(2-ethylhexyl)phthalate) was detected above comparison values in only 1 of the 48 groundwater samples. Three pesticides were detected above comparison values in 1 other of the 48 groundwater samples. Metals, which are naturally occurring in soil and groundwater, were detected above comparison values in 44 of the 48 groundwater samples. Manganese was the only metal detected above its comparison value in 20 of these wells. Although manganese is considered an essential nutrient for humans, inhalation of extremely high manganese concentrations in air can lead to illness. Potential health effects from eating or drinking too much manganese are uncertain. Moreover, most metals, including manganese, do not volatilize from groundwater into the air (ATSDR, 1997a). The highest contaminant concentrations are located at the FFTA, WGL, TLF, and SL. During the RI, the Navy sampled all of the IRP sites at the site and did not identify any groundwater plumes of contamination (Brown and Root, 1997).
A PCE groundwater plume associated with Building 81, located in the central portion of the site, was identified during MCP site investigations. A series of seven investigations have been conducted at Building 81 in the process of characterizing and remediating this plume. These investigations found that the PCE plume is approximately 50 feet wide and 200 feet long and is wholly contained within site boundaries. No private, off-site drinking water wells are located within or proximate to this plume. PCE was found up to a maximum concentration of 1,300 parts per billion (ppb). BTEX (benzene [to 530 ppb], toluene [to 400 ppb], ethylbenzene [to 95 ppb], and xylenes [350 ppb]) was also identified as a component of the Building 81 PCE plume. These investigations also identified an area of LNAPL adhered to subsurface soil as the source of the PCE plume. In summer 1998, the Navy removed approximately 1,250 cubic yards of soil in order to remove the source of the PCE plume. Currently, the Navy is evaluating potential groundwater treatment options to reduce PCE concentrations in groundwater and prevent PCE migration (Tetra Tech NUS, Inc., 1999b).
During the RI, six perimeter monitoring wells were installed around the site. Perimeter or background wells were placed around the site perimeter for two reasons: 1) to gain an understanding of what contaminants may be flowing on-site from off-site sources; and 2) to determine the concentrations of naturally occurring contaminants, such as metals. No VOCs, semivolatile organic compounds (SVOCs), pesticides, or PCBs were detected above comparison values. The metals aluminum, arsenic, beryllium, iron, lead, manganese, and vanadium were detected at concentrations above ATSDR health-based comparison values in five of the six wells (Table 9). Not all of these contaminants were detected above comparison values in each well. These metals are naturally occurring in soil and groundwater and are likely present as a result of natural soil processes rather than as a result of contaminant releases.
The Navy is currently collecting additional samples at IRP sites and other areas of suspected contamination under the Phase II RI and Phase II EBS investigations. These investigations include sampling a total of 120 shallow wells (less than 25 feet bgs), 11 deep wells (greater than 25 feet bgs), and 13 bedrock wells. The purpose of this sampling is to further define the nature and extent of contamination and to evaluate potential contaminant migration. In addition to sampling, these wells will also be used to further refine information regarding groundwater flow (Stone & Webster, 1998; Tetra Tech NUS, Inc., 1998).
Current Exposure Evaluation
On-Site. No on-site personnel or residents are drinking water underlying SWNAS because there are no drinking water wells on site. Therefore, there are no known exposures to on-site groundwater and on-site groundwater poses no public health hazard. The site has received municipal drinking water (from Great Pond) since its inception (Barny, 1997). To determine the extent of site-related contaminants in the groundwater, the Navy sampled 54 monitoring wells with screen depths ranging from 3 to 20 feet, installed at the IRP sites and background locations during the RI. Samples were analyzed for metals, pesticides, PCBs, SVOCs, and VOCs. One VOC (1,2-dichloroethene), three pesticides (heptachlor epoxide, alpha-chlordane, and gamma-chlordane), and several metals, (including aluminum, antimony, arsenic, beryllium, chromium, lead, manganese, thallium, vanadium, and zinc) were detected at concentrations that exceed health-based comparison values (Tables 2 through 9). However, people do not consume this water because there are no on-site drinking water wells.
Off-Site. The adjacent communities of Abington, Hingham, Rockland, and Weymouth have access to municipal water, but some residents maintain drinking water and/or non-potable private wells. Current site data indicate that contaminants are located within site boundaries and have not migrated to surrounding communities. Therefore, it is unlikely that private wells in surrounding communities have been affected by SWNAS and unlikely that off-site residents are being exposed to SWNAS contaminants in groundwater. However, if further site characterization finds off-site contaminant migration, the potential exists that off-site residents could be exposed to contaminated groundwater from potentially impacted wells. If private wells have been affected by SWNAS, off-site residents would be exposed to contaminants through ingestion of water from these wells. Other potential exposures may occur if an impacted well is used to irrigate produce or to fill a swimming pool. Because off-site contaminant migration has not been identified by existing data, these exposures are unlikely.
Because community members are concerned about potential exposures from use of private wells, ATSDR attempted to identify private wells located proximate to SWNAS. Approximately 85 private drinking water wells are thought to exist within 4 miles of SWNAS (EPA, 1997). Based on discussions with community members and the local boards of health, however, ATSDR believes that this may be an underestimate of the actual number of private wells in the area. At the December 7, 1996, SWNAS open house, area residents complained of the rising cost of municipal water from the Massachusetts Water Resources Authority and implied that they would use private wells more regularly as municipal water rates rise. The local boards of health, with help from ATSDR and the Navy, conducted a preliminary survey of private drinking water wells within approximately 0.25 miles of the site and identified eight drinking water wells adjacent to SWNAS property. Figure 6 shows the locations of private wells identified close to SWNAS and the groundwater drainage basins.
In some cases, the local boards of health maintain records of which private wells are used for drinking water (as opposed to non-potable uses). For Weymouth and Abington, the usage of these wells has not been confirmed. It also should be noted that local private well records may be incomplete. This well survey therefore provides only a rough indication of the number and proximity of potential off-site groundwater receptors. A more thorough survey to identify wells and to assess the current usage of identified wells is needed if ongoing investigations indicate that groundwater contamination is migrating off site.
- Abington. The Abington Board of Health maintains a list of private wells. The closest known drinking water well to SWNAS is located approximately 4,000 feet from the southwest fence line. There are approximately 12 non-potable private wells located within approximately 1,000 feet of the southwest corner of the property.
- Hingham. The Hingham Board of Health maintains a list of private wells. The Hingham Board of Health conducted a well inventory in November 1998 to update information for residences near SWNAS. This inventory identified six drinking water wells located approximately 1,000 feet north of the eastern-most edge of the site. There are also five non-potable wells in this area.
- Rockland. The Rockland Board of Health does not maintain a list of private wells. With assistance from ATSDR, the Rockland Board of Health surveyed approximately 450 residences and businesses located proximate to SWNAS to identify private wells. This survey identified nine homes with active non-potable wells. No drinking water wells were identified.
- Weymouth. The Weymouth Board of Health maintains a computer database of private wells. This database shows approximately 21 residences or businesses with wells proximate to the site, 12 of these wells are located on properties abutting SWNAS. Nine wells are listed as irrigation or monitoring wells, and two wells are listed as domestic use. The uses of the remaining ten wells are unknown (Nolan, 1998).
Available data indicate that a small plume of PCE is located in the central portion of the site. However, this plume is located entirely within site boundaries. In summer 1998, the Navy removed approximately 1,250 cubic yards of soil in order to remove the source of the PCE plume. Currently, the Navy is evaluating potential groundwater treatment options to reduce PCE concentrations in groundwater and prevent PCE migration (Tetra Tech NUS, Inc., 1999b). LNAPL found at two MCP sites is undergoing remediation to prevent off-site migration. Aluminum, arsenic, beryllium, iron, lead, manganese, and/or vanadium were detected at concentrations above ATSDR health-based comparison values in five of the six perimeter monitoring wells (Table 9). The two wells with the highest metals concentrations are located at the northern boundary of the site near the main gate. Based on recent site-wide groundwater contours, these two wells are hydrologically upgradient of the site and concentrations may be from naturally occurring metals or metals in groundwater flowing on-site from off-site areas.
Available data from perimeter wells and monitoring wells at IRP and MCP sites indicate that groundwater contamination originating from SWNAS is contained within site boundaries. There is no evidence that contaminants are currently migrating off site. The Phase II EBS and Phase II RI will further characterize groundwater flow and gather more information about existing groundwater contaminants and their migration. The Phase II EBS sampling was completed in winter 1999 and the Phase II RI sampling commenced in spring 1999. Data from these sampling efforts are scheduled to be available for review in summer 2000 (Simenas, 1999). If future investigations indicate that groundwater contaminants are migrating off site at concentrations of public concern, then information from the private well survey should be used to further assess potential exposures.
Past Exposure Evaluation
Although several metals were detected in groundwater monitoring wells at concentrations that exceed ATSDR's comparison values, no one has consumed groundwater at the site. Because SWNAS has always used municipal drinking water, no past exposures to on-site groundwater are believed to have occurred. Available data provide no evidence that contaminants had the potential to reach private wells. Further groundwater information is being collected as described above.
Future Exposure Evaluation
The SSTTDC is currently completing its reuse plan for the site. The plan proposes mixed use of the property, including the development of commercial, residential, and conservation/recreational spaces. Though SWNAS is and would continue to be supplied with municipal drinking water, surrounding communities such as Weymouth are experiencing shortfalls in water supply versus demand (Brian, 1997; SSTTDC, 1999). The aquifer beneath SWNAS therefore might be accessed in the future as a potential municipal water source. State regulations would require more extensive investigation of the aquifer's water quality and potential yield before water supply wells could be developed. Because of these actions, future exposures to contamination through ingestion of this groundwater are not expected to pose a public health hazard. If further characterization identifies the potential for private wells to be affected, appropriate public health actions will be implemented by the Navy and regulatory agencies to prevent exposures.
ATSDR concluded that past, current, and potential future exposures to surface water and sediment pose no apparent public health hazard. This conclusion is based on the following information:
- Surface water sampling detected manganese in French's Stream above drinking water comparison values and sediment sampling detected PAHs and arsenic above soil comparison values. These comparison values may be considered overly conservative (protective of public health) for use with surface water and sediment data because they are derived based on conservative assumptions of daily exposure. French's Stream flows through the western portion of SWNAS along a runway and through residential neighborhoods upon leaving SWNAS. French's Stream is not used as a drinking water supply, but it is used for recreational purposes. Exposures are expected to be infrequent and of short duration.
- Surface water sampling detected antimony and manganese in Old Swamp River above drinking water comparison values and sediment sampling detected PAHs, arsenic, and iron above soil comparison values. Old Swamp River serves as a recreational water body and as a supplemental Weymouth water supply. Old Swamp River flows through the eastern portion of SWNAS along a runway and through residential and commercial neighborhoods upon leaving SWNAS. Exposure during recreational use is expected to be infrequent and of short duration. Whitman's Pond, which is fed by Old Swamp River, provides approximately 10% of Weymouth's water supply, therefore, exposure via the municipal water supply would be minimal.
Hydrology and Surface Water Use
The numerous drainage ditches and channels on the SWNAS property all eventually discharge on site to one of two surface water bodies: French's Stream (on the western side of the site) or Old Swamp River (on the eastern side of the site). Drainage ditches and surface water runoff form the headwaters to French's Stream, which flows southerly along Runway 17-35. Upon leaving SWNAS, French's Stream flows through residential neighborhoods in Rockland and Abington and discharges to Reed's Pond located approximately 1.5 miles south of SWNAS. Along it's length, French's Stream floods during rain storms. People use French's Stream for recreational activities, such as wading and boating. Reed's Pond may also be used for swimming and fishing.
Old Swamp River flows northerly through Rockland and across the eastern portion of SWNAS near the end of Runway 26. Several drainage ditches at SWNAS discharge into Old Swamp River. Upon leaving SWNAS, Old Swamp River passes through residential and commercial neighborhoods in Hingham and Weymouth before discharging to Whittman's Pond, also called South Cove, approximately 4 miles north of SWNAS. People may use Old Swamp River for recreational activities, such as wading and boating. Recreational activities at Whitman's Pond may also include swimming and fishing, however, boating was recently banned. Whitman's Pond also serves as a secondary water supply for Weymouth residents, providing approximately 10% of the town's water. Historically, Whitman's Pond provided up to 20% of Weymouth's water supply (Leary, 1997; MAPC, 1984; Parsons, 1998)
Nature and Extent of Contamination
During the Phase I RI, surface water and sediment samples were collected from French's Stream or drainage channels at the WGL, FFTA, STP, ABTFSA, TLF, and background locations. These sampling locations are shown in Figure 7. Analysis of surface water from French's Stream and drainage channels detected bis(2-ethylhexyl)phthalate, DDD, DDT, Aroclor-1254, and metals above comparison values. Sediment contained PAHs, dieldrin, arsenic, beryllium, and iron above comparison values (Table 10). Samples of leachate from the WGL contained arsenic and manganese and leachate stained soil from the WGL contained dieldrin, arsenic, beryllium, and iron above comparison values. Surface water and sediment samples were also collected from Old Swamp River at the RDA and background locations. Within Old Swamp River, antimony, arsenic, iron, manganese, and thallium were detected in surface water and PAHs, arsenic, and iron were detected in sediment above comparison values (Table 11). Because surface water and sediment comparison values do not exist, ATSDR uses drinking water and soil comparison values, respectively. These comparison values are very conservative (protective of public health) for people who are intermittently exposed to surface water and sediment for short periods of time (such as trespassers or children playing in a stream).
In addition to sampling under the RI, the Rockland Sewer Department collected one surface water and one sediment sample from French's Stream downstream of SWNAS and south of Spruce Street. This sample was analyzed for priority pollutant metals. No contaminants were detected in surface water. Contaminants in sediment were detected below soil comparison values (Town of Rockland, 1997).
Current Exposure Evaluation
On-Site. Runoff from the WGL, FFTA, STP, ABTFSA, and TLF eventually discharges to French's Stream. Runoff from the RDA and SL eventually discharges to Old Swamp River. Sampling of drainage channels and streams detected contaminants above comparison values in both surface water and sediment. However, none of the seven IRP sites or their associated drainage channels are located within residential or recreational portions of SWNAS. On-site residents may contact contaminants detected in on-site surface water or sediment only if they use IRP sites as recreational areas. This is unlikely based on the location of the IRP sites in relation to on-site housing; the closest IRP site (ABTFSA) is approximately 2,000 feet southwest of the on-site housing area. In addition, outdoor recreation is expected to be limited by the seasonal New England climate, including rain, snow, and cold temperatures. On-site surface water is not used as a drinking water supply, therefore, ingestion of surface water would be minimal. The most likely exposures would occur through dermal (skin) contact with surface water and sediments. Skin, however, acts as a barrier for some contaminants, such as metals, thereby reducing potential exposures. Any exposures are likely to be infrequent and of short duration. The contaminant levels detected are not high enough to pose a public health hazard through these likely exposures. Thus, on-site surface water and sediment do not pose an apparent public health hazard.
Off-Site. As French's Stream leaves SWNAS, it flows through residential neighborhoods. Residents along French's Stream likely use the stream for recreational purposes such as wading and boating. Downstream sampling of French's Stream, as it leaves the site property, detected manganese in surface water and arsenic in sediment above comparison values for drinking water and surface soil, respectively. While drinking water and surface soil comparison values assume daily exposures, actual exposures to surface water and sediment are expected to be infrequent and of short duration. Although samples from the downstream locations contained manganese and arsenic at concentrations above comparison values, similar concentrations of these contaminants were also detected in surface water and sediment samples collected from locations upstream of the site boundaries, indicating that such contamination may be caused by off site or natural sources. Sampling by the Rockland Sewer Department did not detect metals in surface water downstream of SWNAS. Sediment samples contained metals at concentrations below comparison values (Town of Rockland, 1997). Based on the low contaminant concentrations detected in samples collected at the site boundary, the absence of contamination in downstream samples collected by the Rockland Sewer Department, and the likely low exposure frequency, surface water and sediment are not expected to present health hazards through recreational use of French's Stream.
Potential exposures also could occur if people consume fish from contaminated surface waters. No fish samples from French's Stream have been analyzed. Although fishing is reported at Reed's Pond, approximately 1.5 miles downstream of SWNAS, it is not known how much, if any, fishing occurs along French's Stream. The Navy is proposing to sample fish tissue samples from downstream surface waters during the Phase II RI (ATSDR, 1997b; Tetra Tech NUS, Inc., 1998).
Old Swamp River also passes through residential neighborhoods as it leaves SWNAS and residents may be exposed to contaminants in surface water or sediment through recreational use. Surface water sampled from Old Swamp River at the downstream site boundaries contained only manganese above its drinking water comparison value and sediment samples contained arsenic and iron above their surface soil comparison values. These metals were also detected above comparison values in the upstream samples, indicating that there may be an upstream source. In addition, antimony was detected in surface water and benzo(a)pyrene was detected in sediment at concentrations above comparison values in upstream samples from Old Swamp River. The source of these contaminants is unknown. It is not known whether contamination exists further downstream because no off-site surface water or sediment samples were collected. While drinking water and surface soil comparison values assume daily exposures, actual exposures to surface water and sediment are expected to be less frequent and of shorter duration. Based on the low contaminant concentrations detected and the likely infrequent exposures, however, off-site surface water and sediment are not expected to present public health hazards from recreational use of Old Swamp River.
People may also be exposed to contaminants in fish tissue. The Isaac Walton Fishing Club in Weymouth has adopted Old Swamp River as a place for fishing and the Massachusetts Division of Fish and Wildlife stocks Whittman Pond and Old Swamp River with trout each spring. This stocking program usually consists of introducing 500 brook trout, each 9 inches or longer in length, at multiple locations where bridges cross Old Swamp River (MAF&W, 1999; Ostertag, 1999). Because annual stocking is required, it is unlikely that the stocked trout remain in Old Swamp River long enough to bioaccumulate high contaminant concentrations. No fish samples from Old Swamp River have been collected, however, the Navy is proposing to collect fish tissue samples from downstream surface waters during the Phase II RI (ATSDR, 1997b). Trout from Old Swamp River are unlikely to serve as a large component of a persons diet because there are no known subsistence fishers. Further, fish are not expected to spend their entire life cycle in waters within and immediately adjacent to SWNAS, thereby limiting the potential for bioaccumulation of contaminants. For these reasons, exposure through consumption of fish is unlikely to result in adverse health effects.
As discussed in "Land Use and Natural Resources," Old Swamp River feeds the South Cove area of Whitman's Pond. The town of Weymouth occasionally pumps water from South Cove to Great Pond, the primary municipal water supply. South Cove is a supplemental water supply that provides a maximum of approximately 10% of Weymouth's total drinking water; the majority of the town's water comes from rain runoff to Great Pond or from groundwater pumped near Great Pond (Leary, 1997). Samples have not been collected from South Cove or from untreated water at Great Pond. The Water Division of the Weymouth Department of Public Works (DPW) treats water from Great Pond by disinfecting it with chlorine, flocculating it with a coagulant to remove suspended solids, and adjusting pH. The water is also treated with a chemical to prevent the release of copper, iron, lead, and manganese from downstream pipes. The Weymouth DPW regularly samples its treated water for organic contaminants and many metals, but it does not analyze its water for all of the metals encountered at SWNAS (e.g., antimony, arsenic, beryllium, or vanadium).
As discussed above, antimony was detected above its comparison value in one upstream surface water sample and manganese was detected above its comparison value in upstream and downstream samples from the Old Swamp River. Although manganese is considered an essential nutrient for humans and only inhalation of extremely high manganese concentrations in air can lead to illness. Potential health effects from eating or drinking too much manganese are uncertain. Moreover, most metals, including manganese, do not volatilize from groundwater into the air (ATSDR, 1997a). In addition, concentrations only slightly exceeded comparison values. Based on the overall lack of contaminants found in surface water from Old Swamp River and given that Old Swamp River supplies only a small percentage of Weymouth's total water, ATSDR believes that exposure through the municipal water supply does not present an apparent public health hazard. If sampling under the Phase II EBS or Phase II RI identifies additional contamination above comparison values, consideration should be given to sampling the Weymouth water supply.
Past Exposure Evaluation
As required for its NPDES permit first issued by EPA in 1975, the Navy has conducted quarterly water sampling from French's Stream at the downstream site boundary. Sampling under the NPDES permit is currently suspended because industrial activities at the site have ceased. The Navy collected one surface water sample at the headwaters of French's Stream in August 1996. The sample was analyzed for petroleum hydrocarbons, VOCs, and benzene, toluene, ethylbenzene, and xylene. None of these contaminants were detected. Based on current sampling at SWNAS and NPDES sampling results, ATSDR believes that past exposure to surface water and sediment from French's Stream through recreational use is not likely to result in adverse health effects.
Little information exists about potential past exposure to contaminated surface water or sediment in Old Swamp River. Exposures may have occurred through recreational use of the river or use of the municipal water supply. Weymouth began using South Cove as a supplementary water source in 1964; although today this water source supplies at most 10% of Weymouth's water, in the past, South Cove is known to have contributed as much as 20% (Leary, 1997; MAPC, 1984). Evaluation of past exposure from recreational use of or to drinking water supplied by South Cove before comprehensive sampling was performed is not possible due to the lack of data. In addition, Weymouth water has never been analyzed for all of the contaminants detected at SWNAS. Based on current contaminant concentrations encountered at SWNAS, likely exposures, and the relatively small amount of drinking water that Old Swamp River contributed to Weymouth in the past, ATSDR believes that past exposure through recreational use of the river or ingestion of drinking water does not present an apparent public health hazard.
Future Exposure Evaluation
Future plans for SWNAS propose commercial, residential, and conservation/recreational site uses. Although specific remediation plans have not yet been determined, they will be based on reuse to prevent future exposures to site contaminants. Thus, potential exposure to sediment and surface water is not expected to pose a future public health hazard.
After detailed review of the available information, ATSDR concluded that past, current, and potential future contact with contaminants in surface soil is unlikely to result in adverse health effects. The following information supports this conclusion:
- Past operations and disposal activities at SWNAS released chemicals into on-site soil. Surface soil samples collected from both IRP sites and background locations contained metals, PAHs, and/or pesticides at concentrations above comparison values. Dioxins were also detected at some IRP sites.
- None of the seven IRP sites are located within residential portions of SWNAS. On-site residents may contact contaminants detected in surface soil only if they trespass to restricted areas of the site. Therefore, any exposures are likely to be infrequent and of short duration. Contaminant levels detected in surface soil are not high enough to pose a public health hazard through these likely exposures.
- The Navy is conducting investigations throughout SWNAS to locate surface soil contamination and identify appropriate remedial actions. Remedial actions, if necessary, will be conducted prior to redevelopment to prevent potential future exposures.
- Contaminants in subsurface soil at the IRP sites are inaccessible, therefore, no exposures are occurring. Any workers that may contact contaminants in subsurface soil during remediation activities will be protected under Occupational Safety and Health Administration (OSHA) regulations.
The majority of SWNAS is occupied by two runways and supporting facilities. On-site housing is located in the northeastern corner of the site. No IRP sites or areas of contamination have been identified in the housing area. Current reuse plans developed by the SSTTDC propose mixed commercial, residential, and conservation/recreational uses of the site. Approximately 930 acres have been set aside for wetlands protection, open space, and recreation, including a golf course. Commercial business and infrastructure, including roadways, occupy approximately 425 acres. The existing on-site housing will remain for use by USCG personnel and additional senior housing and homeless shelters are proposed. Residential areas will occupy approximately 90 acres. None of the proposed housing areas are located within the IRP sites (SSTTDC, 1999).
Nature and Extent of Contamination
Past operations and disposal activities at SWNAS have released chemicals into on-site soil. To characterize on-site surface and subsurface soil, the Navy collected samples during the Phase I RI from the seven IRP sites and from background locations and analyzed them for dioxins, metals, pesticides, SVOCs, and VOCs. These sampling locations are shown in Figure 7. Surface soil samples taken from both IRP sites and background locations contained metals, PAHs, and/or pesticides at concentrations above comparison values. Dioxins were also detected at some IRP sites.
Current Exposure Evaluation
Sites with contaminated soil are located in areas of the site where operations have ceased and are far from on-site housing areas. These sites are not likely to be frequented by residents or trespassers for recreational use. In addition, vegetation covers the contaminated soil in most areas and reduces the potential for exposures to occur. Therefore, exposures by site residents or trespassers are likely to be infrequent and of short duration. Because the detected contaminant levels are not expected to present health hazards through these exposures, on-site soil does not present a public health hazard.
Subsurface soil does not present a public health hazard because contaminants are deep below the ground's surface and inaccessible. On-site workers who might disturb soil in the contaminated areas follow OSHA regulations and wear protective clothing to reduce the risk of exposure.
Past Exposure Evaluation
ATSDR believes it is unlikely that past exposure to surface or subsurface soil presented a public health hazard. When the site was active, security measures included perimeter checks every 4 hours and regular fence maintenance. Trespassing was therefore extremely limited. Contaminated soils were located in operational areas and were generally inaccessible to site residents. Although on-site workers may have been in areas of contamination, ATSDR assumes that workers wore proper protective clothing. Past exposure to surface and subsurface soil, therefore, does not pose an apparent public health hazard.
Future Exposure Evaluation
Site remediation and cleanup, including removal of contaminated soils, will occur based on planned reuses of SWNAS. Current plans developed by the SSTTDC do not propose to locate housing areas within IRP site boundaries (SSTTDC, 1999). Thus, exposure to the site soils in the future will not pose a public health hazard.
ATSDR recognizes that infants and children may be more sensitive to exposures than adults in communities with contamination in water, soil, air, or food. This sensitivity is a result of a number of factors. They are more likely to be exposed because they play outdoors and they often bring food into contaminated areas. Children are shorter than adults, which means they breathe dust, soil, and heavy vapors close to the ground. Children are also smaller, resulting in higher doses of chemical exposure per body weight. The developing body systems of children can sustain permanent damage if toxic exposures occur during critical growth stages. Most importantly, children depend completely on adults for risk identification and management decisions, housing decisions, and access to medical care. Therefore, ATSDR is committed to evaluating their special interests at sites such as SWNAS, as part of the ATSDR Child Health Initiative.
Like other people living or working at or in the vicinity of SWNAS, children may contact contaminated site media. As discussed in the Evaluation of Environmental Contamination and Potential Exposure Pathways section of this PHA, ATSDR evaluated potential exposures to contaminants in groundwater, surface water and sediment, and soil. ATSDR concludes that exposure to site contamination does not pose unique health hazards for children. This conclusion is based on the following information:
- On- and off-site child residents are not exposed to groundwater contamination. On-site residents have never used groundwater underlying SWNAS as a drinking water supply. Eight off-site private wells were identified proximate to SWNAS, however, site investigations have not identified any contamination migrating off-site toward these wells. These wells are unlikely to be affected by on-site groundwater contaminants. State regulations require that site developers perform more extensive investigations of the aquifer underlying SWNAS prior to developing this resource as a drinking water supply.
- On-site drainage ditches and streams containing contamination are located in areas of SWNAS with limited access. On- and off-site child residents would have to trespass in these areas for exposure to occur, therefore, any past or current exposures would be infrequent and of short duration. Off-site residents may use French's Stream and Old Swamp River for recreational uses. Only minimal contamination was detected in either of these streams. ATSDR's evaluation of this pathway used very conservative assumptions designed to protect public health about daily exposures and found no expected adverse health effects. Actual exposures during recreational use are expected to be less frequent and of shorter duration. The Navy is conducting site investigations and evaluating potential remedial actions to ensure that future exposures are prevented.
- Whitman's Pond, which is fed by Old Swamp River, also provides approximately 10% of Weymouth's drinking water supply. Because Old Swamp River only provides a small portion of the drinking water supply and only manganese was detected above comparison values in surface water leaving the site, exposure via the municipal water supply would be minimal.
- Surface soil contamination is located in areas of the site where past operations have ceased. No areas of surface soil contamination are located near residential housing. Children would have to trespass in these restricted areas for exposure to occur. In addition, soil comparison values assume daily exposures, whereas, actual exposures are expected to be less frequent and of shorter duration due to access restrictions. The Navy is conducting site investigations to ensure that future exposures are prevented.
- The Navy, surrounding communities, and regulatory agencies are aware of the contamination issues stemming from activities at SWNAS. The Navy is conducting investigations to identify areas of contamination and determine appropriate remedial actions. Regulatory agencies oversee activities at SWNAS to ensure that proper actions are taken to address existing contamination and prevent future contamination.
1. Community members are concerned about inhalation of, dermal contact with, and ingestion of contaminated water from private wells.
Although Abington, Hingham, Rockland, and Weymouth have municipal drinking water available, there are numerous private drinking water wells in close proximity to the site. The Abington, Hingham, and Weymouth Boards of Health maintain lists of the private wells operated in their towns. The Hingham Board of Health updated their list in November 1998 by sending well inventory forms to residences located near SWNAS. In February and March 1999, the Rockland Board of Health, with assistance from ATSDR, surveyed homes and businesses surrounding SWNAS to locate private wells. Although groundwater contamination has been detected in perimeter wells at the site, there is no evidence of contaminated groundwater migrating off site. No off-site groundwater monitoring data are available to confirm this, however, and the quality of water from private wells has not been assessed. Upcoming investigations should yield more information on groundwater conditions at SWNAS. If future data indicate that contaminants are migrating off site in groundwater at concentrations above health-based comparison values, then potential exposures to contaminants in private wells should be further assessed.
2. Community members are concerned about use of contaminated municipal drinking water.
During the SWNAS open house, some area residents expressed concern that the municipal water system could be, or could have been, contaminated by SWNAS discharges. Old Swamp River feeds the South Cove area of Whitman's Pond. Water is occasionally pumped from South Cove to Great Pond, the primary water supply for the town of Weymouth. South Cove is a supplemental water supply that provides a maximum of approximately 10% of Weymouth's total drinking water; the majority of the town's water comes from rain runoff to Great Pond or from groundwater pumped near Great Pond. Although the Weymouth DPW regularly samples its water for organic contaminants and many metals, it does not sample for all of the metals detected at SWNAS. Of the surface water samples taken from Old Swamp River, upstream samples contained antimony and manganese at concentrations above health-based comparison values; downstream samples contained only manganese at concentrations above comparison values. Based on the overall lack of contaminants found in surface water from Old Swamp River, and given that Old Swamp River supplies only a small percentage of Weymouth's total water, ATSDR believes that exposure through the municipal water supply does not present an apparent public health hazard. ATSDR has, however, recommended that the Navy resample Old Swamp River to confirm the presence of antimony and manganese. This additional sampling is proposed under the Phase II RI. In the past, South Cove supplied a greater percentage (20%) of Weymouth's total water. Based on current contaminant concentrations encountered in Old Swamp River, however, and given the relatively small amount of drinking water Old Swamp River contributed to Weymouth in the past, ATSDR believes that potential past exposure does not present an apparent public health hazard.
3. Community members at RAB meetings have expressed concern about contaminants transported off site from SWNAS via surface water and sediment.
As discussed in the Evaluation of Surface Water and Sediment Exposure Pathway section of this PHA, contaminants were detected at concentrations above comparison values in surface water and sediment. Analysis of surface water from French's Stream and drainage channels detected bis(2-ethylhexyl)phthalate, DDD, DDT, Aroclor-1254, and metals above comparison values. Sediment contained PAHs, arsenic, beryllium, and iron above comparison values (Table 10). Samples of leachate from the WGL contained arsenic and manganese and samples of leachate stained soil from the WGL contained dieldrin, arsenic, beryllium, and iron above comparison values. However, the Rockland Sewer Department collected and analyzed a surface water and sediment sample from French's Stream downstream of SWNAS and south of Spruce Street. These analyses did not detect contamination above comparison values. Within Old Swamp River, arsenic, iron, manganese, and thallium were detected in surface water and PAHs, antimony, arsenic, iron, and manganese were detected in sediment above comparison values (Table 11). Only manganese was detected in the downstream samples above comparison values. It is not known if surface water and sediment in Old Swamp River is contaminated downstream of the site. Based on the low contaminant concentrations in on-site surface water and sediments, however, contaminant migration to off-site surface water and sediment is expected to be minimal and contaminant concentrations are expected to be low.
Because surface water and sediment comparison values do not exist, ATSDR uses drinking water and soil comparison values, respectively. These comparison values assume daily exposures to water and soil, whereas exposures to off-site surface water and sediment are likely to be infrequent and of short duration (such as trespassers or children playing in a stream). Thus, exposure to off-site surface water and sediment are not expected to pose a health hazard.
4. How will the Navy prevent injury from physical hazards, specifically medical wastes reported at WGL, during and after redevelopment?
Although security patrols have stopped and the perimeter fence is no longer monitored regularly, access to SWNAS by trespassers is minimal. The Navy will follow OSHA guidelines and regulations in securing work areas during remediation and redevelopment activities. ATSDR recommends that the Navy remove potential physical hazards, such as medical wastes or scrap metal, during redevelopment to prevent future injury.
5. Community members are concerned about the increased incidence of cancer in the communities of Abington, Hingham, Rockland, and Weymouth.
A RAB member requested that the MADPH conduct a cancer study in communities in close proximity to SWNAS. In response to the request, MADPH evaluated cancer incidence data for 10 cancer types from 1982 to 1992 for the communities of Abington, Rockland, Hingham, and Weymouth (MADPH, 1996). The resulting study is available at the Tufts Library in Weymouth or can be requested directly from the MADPH. Based on the data evaluated, MADPH found no clear pattern of elevations in any one primary cancer site across all four communities. MADPH is continuing to study cancer incidence data for the four towns surrounding SWNAS (Condon, 1998).
The Individuals and families faced with cancer are encouraged to continue to seek medical advice and care from their physicians and health care providers. Based on ATSDR's exposure evaluation and review of existing data, there is no evidence that harmful exposures to contaminants in SWNAS site media are occurring or have occurred. The data from MADPH does not suggest an association between the cancer incidence trends and SWNAS contamination. For more information about the ongoing study, the MADPH , Bureau of Environmental Health Assessment, may be reached by phone at 617-624-5757 or by mail at the following address:
Bureau of Environmental Health Assessment
Massachusetts Dept of Public Health
250 Washington Street, 7th floor
Boston, MA 02108-4619
Bureau of Environmental Health Assessment
Massachusetts Dept of Public Health
250 Washington Street, 7th floor
Boston, MA 02108-4619