PUBLIC HEALTH ASSESSMENT
OLD NAVY DUMP/MANCHESTER LABORATORY (USEPA/NOAA)
MANCHESTER, KITSAP COUNTY, WASHINGTON
EVALUATION OF CONTAMINATION
AND EXPOSURE SITUATIONS
(Includes environmental contamination, pathways, and public health implications.)
Introduction: ATSDR's public health assessments are exposure, or contact driven. Chemical contaminants disposed or released into the environment have the potential to cause adverse health effects. However, a release does not always result in exposure. People can only be exposed to a chemical if they come in contact with the chemical. Exposure may occur by breathing, eating, or drinking a substance containing the contaminant or by skin (dermal) contact with a substance containing the contaminant.
The type and severity of health effects that occur in an individual from contact with a contaminant depend on the exposure concentration (how much), the frequency and/or duration of exposure (how long), the route or pathway of exposure (breathing, eating, drinking, or skin contact), and the multiplicity of exposure (combination of contaminants). Once exposure occurs, characteristics such as age, sex, nutritional status, genetics, life style, and health status of the exposed individual influence how the individual absorbs, distributes, metabolizes, and excretes the contaminant. Together these factors and characteristics determine the health effects that may occur as a result of exposure to a contaminant.
As a result of our site visit observations, and a review of the data currently available, we concluded that three exposure situations pose no apparent public health hazard at this time because the level of contaminants that people are currently exposed to are low and not expected to cause adverse health effects. Additionally, we determined that one situation poses no public health hazard because no one is being exposed.
I. NO APPARENT PUBLIC HEALTH HAZARDS
A. Shellfish Contamination in Clam Bay
Salmon from the net pens and subtidal species such as the horse clam (Tresis capax), geoduck (Panope generosa), and sea cucumbers (Parastichopus californicus) did not contain chemical contaminants at levels of health concern and are therefore considered safe to eat based on chemical contamination levels. [ATSDR does not evaluate biological contamination. The State of Washington Department of Health oversees biological contamination of shellfish in this area.] However, because final remediation plans for the landfill have not yet been determined, ATSDR recommends that engineering controls be instituted to reduce the chance of sediments being stirred up in the water column thus spreading contamination to areas inhabited by subtidal seafood species.
History and Sampling: Chemical contamination from the landfill is the major cause of shellfish contamination in Clam Bay. The 6 acre landfill was used from 1946 through 1962. It was created by filling in the former tidal lagoon located adjacent to the shore (Figure 1). Waste from the area included domestic and wood trash, sludge from the fire training area, and other waste from Puget Sound Naval Shipyard such as metallic and construction debris (1). Landfill wastes protrude out onto the shores of Clam Bay and represents a continuing source of contamination of the bay. The landfill has a man-made fill and soil cap about a foot deep and is currently owned by EPA. Over the years, tidal influences have eroded the shoreline which interfaces with the landfill. Previously disposed landfill material cover the shoreline and no distinguishable zone between landfill and beach is apparent. Leachate seeps from the landfill enter the bay at several points.
Fish and shellfish tissue from Clam Bay were analyzed on two separate occasions. The first by National Marine Fisheries Service in June 1994 and the most recent time as part of the U.S. Army Corps of Engineers Phase II Remedial Investigation (RI) September 1995 (2). NMFS sampled native littleneck (Protothaca staminea), bentnose clams (Macoma nasuta) from the intertidal zones, and salmonids from the net pens. Commercial and experimental production of salmonids is on going in net pens suspended in the middle of Clam Bay approximately 500 yards from shore. For the Remedial Investigation, littleneck and horse clams from the intertidal zones and also geoduck clams and sea cucumbers from the subtidal zones of Clam Bay were sampled. Reference samples were collected from Yukon Harbor (south of the site) and Manchester State Park (north of the site). As part of the RI, 14 samples were collected from 14 stations in clam bay and the reference points (2). ATSDR determined that the list of chemicals for which the fish/shellfish tissue were analyzed was complete and the sampling locations and sample size were appropriate to evaluate the chemical contamination hazard of ingesting fish and shellfish in this area. See Appendix and Table A-1 for assumption, analysis methodology, and data.
The highest concentrations of contaminants were detected in the upper intertidal zone closest to the shore and in species that inhabit that area. The distribution of contaminants is consistent with a source in the landfill which is eroded and suspended in the zone near shore for uptake by filter feeding clams (2). There is a drastic decrease in the contaminant levels in sediment and shellfish further from the shore. As a result, fish and subtidal shellfish did not contain chemical contaminants at levels of health concern.
Present Situation: Currently, signs posted on the beach that state the area is contaminated and advise against shellfish harvesting. EPA posted the signs to warn people about the potential hazard the chemically contaminated beach may have on edible shellfish species that inhabit the beach area at low tide. Additionally, site access controls restrict use of the area by the general public although EPA and NOAA/NMFS employees have access to the beach and other areas.
ATSDR evaluated consumption for recreational and subsistence populations because the Suquamish Tribe expressed concerns to ATSDR about the safety of eating seafood in the area. Subsistence consumers are people whose diet is dependent on the seafood they catch as their primary source of protein. The Suquamish members consider Clam Bay and other areas in Puget Sound as part of their usual and accustomed fishing grounds. We estimated consumption practices for subsistence consumers based on discussions with only a few members of the Suquamish tribe (6).
Based on our estimates for subsistence consumers, clams from the intertidal area contain arsenic, lead, PAHs, PCBs and dioxins at levels that would pose a health hazard to subsistence consumers. Levels of lead are high enough to pose a developmental hazard to the fetuses of pregnant women who consume shellfish solely from this area. Levels of arsenic, PAHs, PCBs, and dioxins pose an increased cancer risk to subsistence consumers. (The appendix provides the details of our estimates.) Since employees of EPA and NOAA/NMFS would eat considerably less than subsistence consumers, they are not likely to experience any adverse health effects from eating contaminated shellfish from the intertidal area for the reported maximum of 6 meals per year. Because remediation plans for the landfill are not final, some remediation alternatives such as partial removal of landfill material from the shoreline could actually cause more contamination to be released into the sediments or water column. Therefore, ATSDR recommends that Clam Bay remain closed to fish and shellfish harvesting until remediation activities are complete and two consecutive sampling events (no sooner that 3 months apart) indicate that fish and shellfish do not contain contaminants at levels of health concern for subsistence or recreational consumers.
Future Situation: There have been discussions between the U.S. Army Corps of Engineers and the Suquamish Tribe about plans to open the area to shellfish harvesters and also to enhance the area to increase the shellfish population (6). Subtidal geoducks, sea cucumbers and salmon did not contain contaminants at levels of health concern for any consumer group and therefore, are safe to eat. However, because remediation plans for the landfill are not final, ATSDR recommends that engineering controls be used to prevent contaminated sediments from moving to areas inhabited by the subtidal species. ATSDR is requesting to review post-remedial sampling data when they become available to evaluate the safety of fish and shellfish.
Because we based seafood consumption estimates for subsistence consumers on discussions with only a few members of the Suquamish tribe, our consumption estimates may not represent the actual consumption practices of the majority of the approximately 400 local Suquamish members living in Kitsap County or the other subsistence consumers harvesting from this area. Our approach may over estimate the health hazard of consuming seafood from Clam Bay and all of Puget Sound and thus be overly protective for chemical exposure. We recognize that recommending the restriction of seafood consumption may compromise much needed nutritional benefits. Therefore, ATSDR is working with the Washington Department of Health and the Suquamish Tribe to conduct a scientific consumption survey of the local members of the Suquamish Tribe to more accurately evaluate the public health hazard of eating contaminated fish and shellfish. The Suquamish tribal members could be an ideal population to survey because they have expressed health concerns to ATSDR and based on their subsistence practices would serve to represent other subsistence populations in the area.
Table 1 - No Apparent Public Health Hazard Situations
| PATHWAY NAME |
CONTAMINANTS | EXPOSURE PATHWAYS ELEMENTS | TIME | COMMENTS | ||||
| SOURCE | ENVIRONMENTAL MEDIA |
POINT OF EXPOSURE |
ROUTE OF EXPOSURE |
EXPOSED POPULATION |
||||
| Fish and Shellfish Contamination in Clam Bay | Arsenic, Lead, PAHs, PCBs, and Dioxins | Landfill major source |
Fish and Shellfish | Eating Fish and Shellfish | Ingestion | EPA, NOAA/NMFS employees who eat seafood from Clam Bay |
Past Present Future |
No apparent public health hazard to employees who consume 6 meals per year of seafood from this area. However, contaminant levels are high enough in intertidal species to present a problem for subsistence consumers. Subtidal species are not a health problem.* |
| Potentially Exposed: Subsistence harvesters who may eat contaminated seafood |
||||||||
| Soil Gas from the Landfill | Methane gas | Landfill | Soil gas | Buildings near the landfill | Explosion Hazard |
Potentially Exposed: Workers in the buildings where explosive gas may accumulate. |
Future |
To date, soil gas measurements have not detected a hazard. However, methane produced naturally as the landfill materials decay may be forced laterally to inland buildings if it is prevented from moving vertically due to something such as non-porous cap placed over the landfill during remediation.* |
| Soil Contamination | Antimony, Arsenic, Cadmium, Chromium, Lead, Vinyl chloride. PAHs, PCBs, and Dioxins/furans | Landfill and Fire Training Area | Soil | Landfill and Fire Training Areas | Accidental Ingestion, Inhalation, and Dermal Contact | Construction, Investigative, and Remediation workers | Past Present Future |
Surface soil contamination levels are too low to pose a health hazard. Subsurface soil levels, even though much greater, do not pose a health hazard to workers who may dig there because of the low frequency and duration of exposure. |
* Current plans incorporate sampling or controls to ensure that potential future situations present no apparent public health hazard.
During the U.S. Army Corps of Engineers Phase I and Phase II Remedial Investigation, test pits were dug into the landfill at Manchester Annex to determine the nature and extent of contamination from the landfill material. Instruments used to detect explosive hazards caused by methane were inserted into the landfill. Although methane was not detected in any of the test pit samples, soil gas at the landfill mainly generated from the natural decomposition of organic materials could theoretically reach explosive levels in enclosed spaces (8). The water table is relatively high at the landfill, (8 - 15 feet below ground surface) maintaining its earlier properties as a tidal lagoon (2). Thus, methane currently generated by the landfill is allowed to escape vertically through the porous soil cap especially when water fills the lower air spaces. ATSDR is concerned that any remediation plans to cap the landfill with a non-porous material could force methane to migrate horizontally to upland areas impacting nearby buildings and creating an explosive hazard in confined spaces such as in breakroom cabinets or small offices. Therefore, ATSDR supports the use of engineering controls by the Army Corps of Engineers when a remediation alternative for the landfill is designed to prevent the possibility of an explosion hazard in nearby buildings.
Presently, construction, investigative, and remediation workers who disturb underlying soils would be the only exposed people. Contaminant concentrations vary widely with only a few samples at levels of health concern. These "hot spots" would not represent the overall exposure of workers. Therefore, the values were averaged and that average used for the exposure estimates (Table A-2). We used highly conservative estimates of frequency and duration of exposure. When there is uncertainty, we over-estimate rather than under-estimate risk by a factor of 10 to 10,000. Thus, the exposure rates we calculated are highly protective of the public's health. See Appendix and Table A-2 for assumption, analysis methodology, and data.
Landfill: The U.S. Army Corps of Engineers conducted a preliminary assessment, and Phase I and Phase II Remedial Investigation at Manchester Annex which provided extensive information about the nature and extent of contamination. Levels of contaminants in surface soils are low and do not pose a health hazard. The landfill is capped with 1-2 feet of clean soil and is grass covered. Therefore, exposure to surface soils is unlikely. Contamination levels are greater in the subsurface soils than in surface soils. Subsurface soils are contaminated with antimony, arsenic, cadmium, chromium, lead, vinyl chloride, PAHs, PCBs, and dioxins/furans. However, this contamination is well below ground surface, where it does not pose a health threat. Workers exposed to subsurface soils are not likely to experience adverse health effects from their exposures because average contaminant levels are low and exposures would be relatively short in duration and frequency (less than daily for 30 years). Protective clothing as required by the Occupational Safety and Health Agency (OSHA) will minimize any exposure.
Fire Training Area: The fire training area (FTA) was built in 1942 of concrete structures made to resemble ship features and was used to train Navy personnel to extinguish ship fires (Figure 1). Trainees would practice putting out fires resembling ship fires which were set here using gas, diesel fuel, and waste oil. Associated with the FTA were underground storage tanks containing gas, diesel, waste oil, fuel lines, water lines and pumps (2). Reports indicated that this area may have been used until the 1970s (1). The concrete structures are several stories high and contain sludge and dirt. A marshy bog is present within one of the structures and is several feet high. The 22 acres which include the Fire Training Area are owned by NOAA/NMFS.
Environmental investigations at the fire training area detected PAHs, dioxins, PCBs, and total petroleum hydrocarbons in the soil with contaminant levels greatest in the subsurface soils. Levels in surface soils do not pose a health hazard to workers. Concrete structures three stories high used to simulate ship components are still in place. PAHs and dioxins/furans were most likely generated from the burning of PCBs, waste fuels, and other organo chlorine chemicals during training exercises when the area was used (1942-1970). Contaminant levels in subsurface soils do not pose a health hazard to workers who would incidentally ingest, inhale or dermally contact contaminated soils. Evaluation of workers' exposure to subsurface soil is included in the Appendix.
Net Depot: The net depot is approximately 5 acres in size and was used in the 1940s for construction, repair, and storage of submarine nets made of steel cable which were suspended in water of the coastal passes (Figure 1). These nets acted as underwater fences to protect important military areas from access by enemy submarines. The net depot area which contained a large concrete pad and several buildings was also used for buoy maintenance. Activities which included sandblasting, painting, and machining ceased in 1950 when the area changed use to a boat storage area (1). The area currently includes the same concrete pad and buildings. Over the years, additional structures and a pier have been built (2). EPA now owns this area.
Low levels of soil contaminants (total petroleum hydrocarbons and PCBs) have been detected in both surface and subsurface soils where the net depot operated (2). There is no indication that migration of contaminants from this area has occurred. Because most of the area is covered by a concrete pad and parking lot, it is not easily accessible to workers. Inaccessibility and low contaminant level make exposure to the soil at the net depot no apparent health hazard.
Although groundwater contamination at Manchester Annex is in the shallow aquifer, no one is currently drinking contaminated water. Drinking water wells are located upgradient to the site and tap the deeper Outwash Channel Aquifer. Antimony, arsenic, beryllium cadmium, lead, and benzene were detected in the shallow aquifer at levels approximately 10 times greater than allowable for drinking water. However, because no one is drinking this water it is not a health hazard. Contribution of the shallow aquifer to the deeper drinking water aquifer, (Outwash Channel Aquifer) is not likely since the nature of groundwater flow is upward and out toward Clam Bay. Additionally, any mixing of the aquifers would greatly reduce the contaminants to levels that would most likely be non-detectable.
Drinking water for EPA and the NOAA/NMFS facilities is provided by the town of Manchester which gets their water from inland wells in the Outwash Channel Aquifer (7). The Navy's fuel supply depot located south of Manchester Annex uses wells (Numbers 4, 5, and 6) which also lie in the deeper Outwash Aquifer (2). These wells are currently not affected by the contamination from Manchester Annex and would not likely be affected in the future due to the shallow nature of contamination and the direction of ground flow being upward and toward Clam Bay.
Groundwater contamination at Manchester Annex lies in the shallow aquifer 10-15 feet deep (surficial fill including the landfill saturated zone). Water in the shallow aquifer is not suitable for drinking water due to salt water intrusion (2). The major sources of contamination of the shallow aquifer come from the migration and leaching of contaminants from soils in the landfill and fire training area. It is hard to predict whether contaminants in the shallow aquifer are decreasing because leaching of heavy metal contaminants from soils into the groundwater may continue possibly due to the interaction of salt water with landfill materials may continue.
Contamination of the shallow aquifer does not appear to be widespread. Additionally, contaminant levels do not indicate either temporal or spatial trends. Nine monitoring wells were installed at the landfill and fire training area. Samples from the wells were collected in January, April, and September 1995. Four temporary well points were also installed in the landfill test pits. Samples from those test pits were collected in November 1994. Eighteen groundwater samples were collected from these newly dug wells and others previously installed (referred to as Navy wells) wells. Samples from monitoring well 95MAN001MW003 in January 1995 contained elevated levels (10-1000 times higher than other samples and also safe drinking water levels) of total metals antimony (125 part per billion - ppb), arsenic (93 ppb), beryllium (4.2 ppb), cadmium (105 ppb), chromium (419 ppb), copper (3130 ppb), lead (2280 ppb), and zinc (24100 ppb). However, samples taken from that same well in subsequent months April, and September showed no elevated levels. Likewise, well 95MAN003MW004 showed elevated levels (10 times higher) for cadmium (123 ppb), chromium (28 ppb), copper (1330 ppb), lead (85 ppb), and zinc (3730 ppb) as did its duplicate sample; however, previous samples (from January and April) from that well did not indicate elevated levels. Several variables such as rainfall/seasonal influence, heterogeneity of the landfill materials, and subtle changes in groundwater flow rate or subtle temporary directional changes may account for such variability in the data.
Groundwater flow at Manchester Annex is in the direction of Clam Bay, which acts like a sink. The vertical gradient is generally upward which limits the likelihood that contaminants would migrate to deeper groundwater zones even though at times during the sampling a minor downward gradient was noticed (2). Increasing the potable well pumping volume and duration could also temporarily change the direction of groundwater flow. Such extreme conditions would only slightly impact the deeper Outwash Channel Aquifer (previously called the Navy Aquifer) because of the tremendous dilution that would occur when a small volume of low- level contaminants is added to an enormous volume such as the Outwash Channel Aquifer. This dilution would most likely not be detectable because contamination was sporadic and not widespread.
Future well development on the site could also impact the groundwater flow; however, it is unlikely that any impact would result in people drinking contaminated water at levels of health concern. Moreover, initial sampling of newly developed wells, as required by the State of Washington and the Federal Clean Water Act, would ensure that no one would drink contaminated water at levels of health concern.
Table 2 - No Public Health Hazard Situation
| PATHWAY NAME |
CONTAMINANTS | EXPOSURE PATHWAYS ELEMENTS | TIME | COMMENTS | ||||
| SOURCE | ENVIRONMENTAL MEDIA |
POINT OF EXPOSURE |
ROUTE OF EXPOSURE |
EXPOSED POPULATION |
||||
| Groundwater Contamination | Antimony, Arsenic, Beryllium, Cadmium, Chromium, Copper, Lead, and Zinc | Landfill and Fire Training Area | Groundwater | Drinking Water Taps | Ingestion | No one is exposed. | Future |
No one is currently drinking contaminated water. Shallow aquifer may be hydraulically connected to drinking water wells; however, contaminant levels would be non-detectable and therefore, not a health hazard. |
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