PUBLIC HEALTH ASSESSMENT
LORING AIR FORCE BASE
LIMESTONE, AROOSTOOK COUNTY, MAINE
ENVIRONMENTAL CONTAMINATION/ PATHWAYS
ANALYSIS/PUBLIC HEALTH IMPLICATIONS
We describe here one situation in which significant concentrations of contaminants are present, but measures are in place to prevent exposure; a second where measures prevent possible future exposure; and a third where remedial activities will prevent future exposures to hazardous levels of contaminants. In three other situations, low levels of contamination are present, but no one is being exposed or expected to be exposed in the future at concentrations of concern. In this section we will discuss available information that relates to our analysis and suggest means to mitigate risks. When appropriate, we list additional information that should be gathered in a situation to add data necessary for a complete determination.
ATSDR's public health assessments are exposure, or contact, driven. Chemical contaminants disposed of or released into the environment at LAFB have the potential to cause adverse health effects. However, not all releases result in exposure. Persons can only be exposed to a chemical if they come in contact with that chemical. Exposure may occur by breathing, eating, or drinking a substance containing the contaminant or by skin (dermal) contact with a contaminated substance.
The type and severity of health effects that occur in an individual from contact with a contaminant depend on (a) exposure concentration (how much), (b) frequency and/or duration of exposure (how long), (c) route or pathway of exposure (breathing, eating, drinking, or skin contact), and (d) the multiplicity of exposures (combination of contaminants). Once exposure occurs, characteristics such as age, sex, nutritional status, genetics, lifestyle, and health status of the exposed individual influence how that individual absorbs, distributes, metabolizes, and excretes the contaminant. Together these factors and characteristics determine what health effects may occur as a result of exposure to a contaminant.
I. NO APPARENT PUBLIC HEALTH HAZARD
ATSDR concluded that three situations concerning the LAFB installation pose no apparent public health hazard: 1) catching fish from waters affected by base-associated contaminants, 2) drinking water from off-site or on-site water wells, and 3) wading and swimming in on-site waterways.
A. Catching Fish from Waters Affected by Base-Associated Contaminants
Evaluation of chemical and toxicologic data from analysis of fish fillets sampled from certain surface waters on-base and off-base showed increased carcinogenic and noncarcinogenic risks from eating such fish. Fish taken from the West Branch, Greenlaw Brook (WBGB), Malabeam Lake, Chapman Pit Pond, Green Pond, and East Branch, Greenlaw Brook (EBGB) (entirely or primarily on-base) and from Greenlaw Brook, the lower Little Madawaska River (downstream of base influence), and Wolverton, Brandy, Factory, and Nichols Brooks (entirely or primarily off-base) contain contaminants at levels of concern (Figure 2). The greater risks result from increased concentrations of polychlorinated biphenyls (PCBs) from Arochlor 1260 (most of the above-cited waterways) and from elevated polycyclic aromatic hydrocarbons (PAH) levels (Malabeam Lake only), contaminants that are associated with past base activities. Background data were gathered from water bodies north of the base, such as Butterfield Lake, which are not impacted by on-base contamination. The lower risk associated with background sites is due mainly to residues of DDT and its two major degradation products remaining from earlier widespread use of DDT in agricultural areas. The risk equation, values substituted for the various parameters, and a sample calculation are shown in Appendix C.
The risk values for consumption of fish caught in the above-mentioned waters exceed the Maine Department of Human Services (MDHS) cancer guideline. As a result, MDHS established a catch-and-release fish advisory in 1996 that warns against ingestion of fish taken from the Little Madawaska River (LMR) and its tributaries between the Little Madawaska Reservoir Dam and Grimes Road, just upstream of the confluence of the LMR with the Aroostook River (Figure 2).5 (Figure 3 shows the location of the LMR and tributaries relative to LAFB boundaries). A fish advisory was enacted and publicized to protect the public from risks associated with eating contaminated fish from these waters.
The MDHS advisory and an accompanying fact sheet were distributed widely to print media, radio and television stations, community groups, and individuals. Affected water bodies were posted to reflect the catch-and-release edict. Details of the fishing advisory have now been included in the Maine 1998-1999 Open Waters Fishing Regulations provided to everyone purchasing a fishing license in Maine, alerting anglers to risks inherent in consuming fish from designated waters.
PCB levels in fish are expected to drop over time. The BRAC Cleanup Team (BCT) projects that concentrations of PCBs will be low enough in five to ten years for the fish advisory to be lifted.6 A plan should exist and be funded by AFBCA to monitor PCB levels in fish at three- to-five-year intervals and to include samples taken from Green Pond, Greenlaw Brook, and the LMR.
Low levels of DDT, DDE, and DDD found in fish from Butterfield Brook and East Loring Lake on LAFB are thought to be due to widespread spraying of DDT in years before use of DDT was banned in the United States and not associated specifically with former base activities. The less than 1 milligram/kilogram (mg/kg) total concentrations found do not represent a public health hazard at the consumption rates that may be reasonably associated with fishers of these waters.
Several considerations argue against significant past exposure of persons to PCBs in fish at or near LAFB. PCB concentrations undoubtedly were smaller in the affected waterways previously, since PCB contamination resulted cumulatively during the years of LAFB operation. Also, the LMR, a much larger fishery than the EBGB, has the fish with lower PCB levels. Additionally, anglers have had an abundance of alternative fishing waters in the nearby area. Finally, a study by Duggan et al.7,8 in 1983, part of a federal monitoring program conducted by the U. S. Food and Drug Administration (FDA) and the U.S. Department of Agriculture (USDA), measured PCB concentrations in dairy products and raw meats in the United States during the years 1970 to 1976. Forty-six percent of 2901 samples of fish were positive for PCBs, and all 2901 results were averaged to yield a result of 0.892 ppm (µg/g) in fish. This value, reflective of fish marketed for human consumption throughout the United States in the 1970s, is comparable to concentrations found in fish from the EBGB and LMR at the inception of the MDHS fish advisory (Appendix C). The FDA has established an upper limit of 2 ppm (µg/g) of PCBs in food fish to protect the public from harmful health effects.9 The MDHS fish advisory is more restrictive than the FDA requirement for PCBs in fish. It is unlikely that any adverse health effects have occurred in the past that are attributable to PCBs in fish from waters covered by the fish advisory.
Figure 2. Location of Fish Advisory
Table 1. No Apparent Public Health Hazard Situation: Fish in
Waters Affected by Base-Associated Contaminants
| PATHWAY NAME | CONTAMINANTS |
EXPOSURE PATHWAYS ELEMENTS |
TIME | COMMENTS | ||||
|
SOURCE |
ENVIRONMENTAL MEDIA |
POINT OF EXPOSURE |
ROUTE OF EXPOSURE |
POTENTIALLY EXPOSED POPULATION |
||||
| Contaminated fish in the lower Little Madawaska River and site-associated tributaries, on-base and off-base. |
PCBs*, PAHs**, pesticides |
Releases of hazardous substances to soils, surface water, and groundwater from flight operations, from transformer leaks and other PCB spills, and from disposal on base |
Fish |
Eating contaminated fish |
Ingestion |
Potentially Exposed: |
Past Current Future |
Details of the State of Maine fish advisory proscribing consumption of fish in the affected waters are now included in the Maine 1998-1999 Open Water Fishing Regulations provided to all purchasing a fishing license. |
|
Conclusions and Public Health Action Plan: Fish from Waters Affected by Base-Associated Contaminants and Covered by the Maine Department of Human Services Fish Advisory, Issued April 18, 1996. Conclusions:
Action in Effect:
Recommendation:
|
B. Drinking Water from On-Site or Off-Site Water Wells
1. On-Site Wells: Numerous water supply wells have been installed on-site at LAFB, beginning with the initiation of construction of the base around 1947 and continuing until at least 1985. Most of the wells were constructed in the period from the late 1940s through the middle 1950s. There are at least 35 such wells on base.10 None of these wells are now used to supply drinking water on the installation.11 In 1957, when the output of the wells was projected to be insufficient for future LAFB needs, the Little Madawaska River (LMR) Reservoir facility was constructed to supply the base. Although the main water system at Loring has been supplied exclusively from the LMR Reservoir since completion of the facility in 1960, individual wells supplied potable water to persons at a few remote locations on the installation until the base was closed in 1994. Extensive, low-level groundwater contamination resulted on the developed western portion of the base from previously accepted hazardous material handling and disposal practices at LAFB. However, the deep groundwater is typically in a discharging (artesian) condition in the areas of significant surface water and groundwater contamination, i.e. the FLDD, FLDD Wetland, and the EBGB. Thus, shallow groundwater is forced to the surface and carries attendant contamination, if any, down the EBGB, not to deeper groundwater aquifers. When remediation is complete at Loring, most water supply wells will have been abandoned and sealed according to acceptable criteria. The BCT is developing a long-term, groundwater monitoring plan that should be available in early 1999; this plan will stipulate which wells will be retained as monitoring wells or for other potential uses and which will be abandoned and sealed.6 No-pump areas and compliance boundaries will also be identified. Parcels transferred to new owners will be conveyed by deeds stipulating restrictions on installation of potable-water wells on the properties. Potable water will continue to be available from the LMR Reservoir for properties transferred through the Loring Development Authority.
What was to become LAFB was constructed from forest and wetland in the late 1940s and early 1950s. Water wells on LAFB supplied all base needs from the arrival of the first Air Force unit in 1950 until the LMR Reservoir came on line in 1960. Negligible contamination of groundwater occurred during this period, and the primary water source has been the uncontaminated reservoir water ever since. Five wells have provided potable water during periods after 1957 to a limited number of persons. Well # 20 and its backup, Well # 9, supplied up to 100 persons in the Weapons Storage Area of East Loring for eight hours per day from 1952 until 1994.12 These wells are in deep bedrock at depths of 323 and 275 feet, respectively. There is moderate contamination of shallow groundwater in this area; however, bedrock in this area shows low transmissivity below 45 feet. There is an upward hydraulic influence (water at lower levels in bedrock exerts upward pressure) and the shallow bedrock has been shown to discharge to overburden which, in turn, discharges to surface water (East Loring Lake and Butterfield Brook).13 Significant levels of contaminants do not travel to the depths from which the wells drew water when they were in use. The DRMO Well, also on East Loring, was in service during the years 1966 to 1994 and served a small number of persons. This well is in an area with little groundwater contamination and not within a designated groundwater flow field, an area of concern defined by demonstrated groundwater contamination, potential flow pathways, and discharge zones. The sewer treatment plant water well remains in service on base but is no longer used for drinking water purposes. Also, neither this well nor the weather station well are located in a designated OU12 flow field. The ski chalet well supplied drinking water to guests in the past but is no longer used to provide potable water. The low levels of groundwater contamination in the areas of these latter four wells make it unlikely that any contamination of water in the wells has occurred. There is no indication of past exposures to contaminants in drinking water on base that would have posed a health hazard. Currently, no exposures to contaminated drinking water are occurring. Deed restrictions limiting construction of new wells on transferred properties are designed to prevent future exposures to contaminated drinking water.
2. Off-Site Wells: The Air Force undertook sampling of private wells at the East Gate Estates and West Gate Villa mobile home parks. Wells within a 0.5 mile radius of the Receiver Site, Landfills #2 and #3, and the Fuels Tank Farm/East Gate Waste Storage Tanks were also selected for sampling. Sampling and chemical analysis were to address concerns that on-base contaminants might have migrated to these wells. An ATSDR Health Consultation released in February 1993 addressed the results of the chemical tests.14 Eleven of 13 properties served by wells meeting the criteria for testing were sampled. The owners of the other two properties shared another well, but attempts to arrange sampling in the same round were unsuccessful. Manganese was the only contaminant of public health concern identified. This contaminant was detected at a concentration of 1840 mg/kg in the well at Carpenter's Service Station. ATSDR concluded that the well could be safely used for such activities as washing cars but should not be used as a residential or business drinking water source. The manganese is not believed to be associated with the LAFB installation.14 A copy of the February 1993 consultation is included in the present document as Appendix D.
Since the publication of the 1993 health consultation (Appendix D), the remaining well has been sampled and analyzed. All analyte concentrations were below levels of concern.15 Another well location has been identified that meets the original criteria for sampling off-base wells, but, based on known groundwater contours and monitoring-well-sampling results, the resident is not at risk.16 The nearest downgradient well to Landfill 2 (Well G-H) is being sampled on an annual basis. No contaminants have been found in this well at concentrations of concern. Monitoring wells just off base and to the northwest of Landfill 2 yielded samples showing vinyl chloride concentrations in the range of 0.15 to 1.0 parts-per-billion (ppb), where Maine's screening value is 0.15 ppb and the USEPA's is 2.0 ppb.6 The direction of groundwater flow in the area is to the northwest. No concentrations above screening values have been seen for vinyl chloride or any other contaminants in the array of monitoring wells to the west, between Landfill 2 and Well G-H. No evidence of past or current exposures to contaminants in drinking water from off-base water wells has been seen. Long-term monitoring of OU12 and OU4 groundwater is designed to protect the purity of off-base water wells in the future.
Table 2. No Apparent Public Health Hazard Situation: Drinking Water from On-Site or Off-Site Water Wells
| PATHWAY NAME | CONTAMINANTS |
EXPOSURE PATHWAYS ELEMENTS |
TIME | COMMENTS | ||||
|
SOURCE |
ENVIRONMENTAL MEDIA |
POINT OF EXPOSURE |
ROUTE OF EXPOSURE |
POTENTIALLY EXPOSED POPULATION |
||||
| Basewide groundwater (OU12) and on-site water wells |
Fuel-related compounds, VOCs (including chlorinated solvents), pesticides, metals |
Releases of hazardous substances to soils, surface water, and groundwater from flight operations and support functions |
Groundwater |
Water from taps in on-base locations that rely on wellwater | Ingestion, direct contact, or inhalation (of vapors) of contaminated wellwater | Potentially Exposed: Persons drinking water from a on-base water well that becomes contaminated |
Past Current Future |
No wells on the Loring facility are known to be used currently for drinking water. Potable water has been supplied from the Madawaska Reservoir water system since 1960. Conveyance of parcels will include stipulations against constructing wells to provide water for drinking purposes. |
| Basewide groundwater (OU12) and off-site water wells |
Fuel-related compounds, VOCs (including chlorinated solvents), pesticides, metals |
Releases of hazardous substances to soils, surface water, and groundwater from flight operations and support functions |
Groundwater |
Water from taps in private residences or businesses nearby (<1 mile) that rely on wellwater |
Ingestion, direct contact, or inhalation (of vapors) of contaminated wellwater | Potentially Exposed: Persons drinking water from an off-base water well that becomes contaminated |
Past Current Future |
Off-base water wells near the installation have tested free from base-associated contamination. Measures are in place to assure that these wells will not be impacted in the future by unacceptable levels of contaminants from OU-12 groundwater. |
| Landfill-associated groundwater
(OU4) and off-site water wells |
Fuel-related compounds, VOCs (including chlorinated solvents), pesticides, 2,6-dinitrotoluene, metals | Landfills two and three | Groundwater (OU4) |
Water from taps in private residences or businesses nearby (<1 mile) that rely on wellwater | Ingestion, direct contact, or inhalation (of vapors) of contaminated wellwater | Potentially Exposed: Persons drinking water from an off-base water well that becomes contaminated |
Past Current Future |
Off-base water wells near the installation have tested free from base-associated contamination Landfill effluents will be monitored for at least 30 years after closure of the landfills to evaluate and mitigate any threat to aquifers. |
VOCs - Volatile Organic Compounds
|
Conclusions and Public Health Action Plan: Drinking Water from Off-Site or Approved On-Site Water Wells Conclusions:
Planned Actions:
Recommendation: ATSDR requests that it be provided a copy of the long-term groundwater monitoring plan for review when the plan becomes available in draft form for comment. |
C. Wading and Swimming in On-Site Waterways
Considerable data are available to evaluate risks that might be posed by contamination in brooks, streams, and ponds on the Loring installation. Much of this information is contained in the Basewide Surface Water/Sediment Operable Unit (OU13) Remedial Investigation Report.17 The BCT calculated acceptable risks and corresponding soil and sediment cleanup levels based on future land-use scenarios (residential, recreational, industrial/commercial) as defined in the Record of Decision for Disposal of Loring Air Force Base, Maine, April 1996.1 AFBCA contractors performed removal actions as necessary, guided by analytical results.
Wolverton Brook and Brandy Brook are southwestwardly flowing tributaries of the Little Madawaska River, which itself flows south toward its confluence with the Aroostook River southeast of the town of Caribou (Figure 2). The Wolverton Brook/Brandy Brook Study Area is located along the western side of LAFB and is approximately 4600 acres in size, about 700 acres of which are within LAFB boundaries (Figure 3). Risks were calculated for a scenario positing child trespassers, 6 to 16 years of age, experiencing recreational exposure to contaminants in surface water and sediment while wading and surface soil while playing.18 Risks for surface water, sediment, and soil pathways were less than the MEDEP cancer guidance value of 10-5, the value accepted by ATSDR for this public health assessment as being protective of public health. This guidance value corresponds to a 1 in 100,000 (0.00001) increase in the lifetime risk of cancer from spending 26 days/year for 11 years wading and playing in this area. The doses of noncarcinogenic contaminants were smaller than quantities that could result in health effects. Wading and playing in the Wolverton Brook/Brandy Brook Study Area pose no apparent public health hazard.
The Flightline Drainage Ditch (FLDD) is located in the south-central part of the base, west of the flightline and south of the nose-dock area. The FLDD is a 20 to 25 feet wide, about 2,500 feet long, unlined, drainage channel. The FLDD extends from a triple-culvert headwall and drains the flightline area. It passes through the Spill Containment Facility (SCF), continues through the FLDD wetland, and flows into the East Branch of Greenlaw Brook (EBGB), which joins the West Branch of Greenlaw Brook (WBGB) before the confluence of Greenlaw Brook with the Little Madawaska River (Figure 3).
The January 8, 1997, ATSDR Health Consultation for LAFB recommended that wading in the FLDD be prohibited due to risk attributable to levels of PCBs found in water sampled from the FLDD/FLDD wetland area.19 Cancer risks greater than 10-4 were calculated20 for the trespasser child (6 to 16 years old), substantially higher than the MEDEP permissible value of 10-5. However, the ban on wading prevented such exposures. A remedial action was undertaken in the summer of 1997 to excavate areas of the FLDD, FLDD Wetland, and EBGB to remove PCBs and other contaminants. Work was completed on the FLDD and FLDD Wetland during 1997. There was confirmatory analysis of sediment and water by AFBCA contractors demonstrating achievement of the acceptable concentrations of 1 ppm PCBs in stream sediment and 5 ppm in flood-plain sediment in the completed areas.6, 21 The ban on wading has been lifted from the FLDD and none will be imposed on the FLDD Wetland. The remediation plan is set out in the Record of Decision for OU13. Remaining excavation work, essentially that on the EBGB downstream of Station 52+00 to the LAFB boundary, was completed by the end of 1998 and will be followed by long-term monitoring to assess the effectiveness of the remediation process.22
Figure 3. Location of OU 13 Study Areas
The SCF is an oil-water separator located on the western bank of the lower end of the FLDD and upstream of the FLDD wetland. SCF sediment "hot-spots" were excavated and the removed sediment properly disposed of during OU13 remediation. Further, the SCF is within a chain-link fence and secured by a locked gate. Potential human carcinogenic risks are less than the MEDEP cancer guidance value, and noncarcinogenic risks are also less than USEPA and MEDEP guidelines. Therefore, the Spill Containment Facility poses no apparent public health hazard.
The East Branch of Greenlaw Brook (EBGB) begins in a wetland south of the Fuels Tank Farm, flowing westerly 2,500 feet to its confluence with the FLDD Wetland drainage (Figure 3). The EBGB continues westerly, combining with the WBGB and then merging with the Little Madawaska River. A total of 29 IRP sites are located near the EBGB, and several are known to have contributed contaminants, including the Fuels Tank Farm, Base Laundry, Refueling Maintenance Shop Area, and Coal Storage Pile/Fly Ash Area. The EBGB has also been impacted by contaminants flowing downstream from the flightline area via the FLDD and FLDD Wetland. Primary contaminants in the EBGB include polyaromatic hydrocarbons (PAHs), total petroleum hydrocarbons, chlorinated pesticides (including DDT metabolites and chlordane), PCBs, and lead, among other inorganics. Even so, "...potential human health recreational carcinogenic risks associated with recreational exposure to surface soil, sediment, and surface water in this study area are within or below the USEPA carcinogenic risk range".23 Carcinogenic risks were also at or below the 10-5 MEDEP acceptable risk value except for RME "reasonable maximum exposure" sediment values at the EBGB and at the Ditch G12 PCB hot spot. An RME sediment value at the hot spot also provides the only noncarcinogenic risk value above acceptable risk. These hot spots have been or are being addressed by excavation and removal of sediment and soil from the EBGB and Ditches G11 and G12. AFBCA contractors will take sediment, soil, and fish samples and perform chemical and biological assays to evaluate the effectiveness of these removals.
The WBGB begins in a wetland north of the Flight Line Area and about 750 feet west of the base boundary (Figure 3). The WBGB flows south onto base property, passes west of the Quarry and Nose Dock area, and forms Malabeam Lake. Upon leaving the lake the watercourse forms and then exits Chapman Pit Pond. About 3.4 miles from its source the WBGB merges with the EBGB. The WBGB Study Area contains five IRP sites, including the Quarry, the Nose Dock Area, the Base Exchange Service Station, Landfill 1, and the Chapman Pit Disposal Area. Green Pond, beaver ponds, and several drainage ditches and wetlands are also within this study area. Primary contaminants detected in the WBGB Study Area were PAHs, total petroleum hydrocarbons, and metals such as cadmium, lead, manganese, silver, barium, and zinc. However, potential human health carcinogenic risks in this study area, associated with exposure to sediment, surface water, and surface soil, are at or below the cancer risk guidance value of 10-5. Average concentrations for noncarcinogenic effects of contaminants resulted in risks that are acceptable by USEPA and MEDEP guidelines.24 Exposure to surface water, sediment, and soils along the WBGB poses no apparent public health hazard to persons wading or playing.
The Little Madawaska River (LMR) flows south from the dam forming the Madawaska Reservoir and follows a course about 1.5 miles west of the LAFB boundary (Figures 2 and 3). Its tributaries include Wolverton, Brandy, and Greenlaw Brooks. The LMR joins the Aroostook River a few miles south and east of the city of Caribou. Greenlaw Brook is the primary pathway carrying base-related contaminants toward the LMR. However, chemical analysis of predesign and OU13 Remedial Investigation samples of Greenlaw Brook sediments west of the culvert plunge pool under Sawyer Road showed concentrations of PCBs to be below the remediation goals of 1 mg/kg for stream sediments and 5 mg/kg for sediments or soil in the floodplain.6 Potential current and future carcinogenic and noncarcinogenic risks for surface water and sediment in the LMR are well within the USEPA and MEDEP guidelines for all wading and swimming scenarios used in risk calculations. Risk calculations and values chosen for risk-related parameters are shown in Appendix W of Reference 15. Values chosen for parameters in the risk equations are conservative (protective of public health) and are acceptable to ATSDR. The impact of future groundwater discharge on surface water contaminant concentrations was modeled; the impact of such discharge on future surface-water risks is negligible.25
Butterfield Brook (BB) flows south onto the eastern side of LAFB and into East Loring Lake, a 40-acre impoundment surrounded by the Weapons Storage Area (Figure 3). Willard Brook joins BB as the latter flows from East Loring Lake to Durepo Reservoir, an 80-acre, man-made water body just south of the base boundary. The flow from the reservoir is joined by Durepo Stream from the east to form Limestone Stream (LS). LS enters the Aroostook River 10 miles further south. There are a number of Installation Restoration Program (IRP) sites within the BB/LS Study Area that might contribute contaminants to surface water, including the Railroad Maintenance Site, Fire Training Area, Underground Transformer Site, and the 9,000 Debris Area.26, 27 The Underground Transformer Site Wetland required excavation to achieve an acceptably low level of risk.28 However, risk assessment calculations show that recreational exposure to surface soil, sediment, and surface water in this area are within USEPA and MEDEP guidelines for both cancer and noncancer risk.29 These surface-water bodies pose no apparent public health hazard to persons wading or swimming.
Table 3. No Apparent Public Health Hazard Situation: Wading and Swimming in On-Site Waterways
| PATHWAY NAME | CONTAMINANTS |
EXPOSURE PATHWAYS ELEMENTS |
TIME | COMMENTS | ||||
|
SOURCE |
ENVIRONMENTAL MEDIA |
POINT OF EXPOSURE |
ROUTE OF EXPOSURE |
POTENTIALLY EXPOSED POPULATION |
||||
|
Surface Water and Sediments in On-site Waterways |
PCBs, pesticides, PAHs, metals |
Releases of hazardous substances to soils, surface water, and groundwater from flight operations and from transformer leaks and other PCB spills and disposal on base |
Sediment and surface water |
Skin contact and incidental ingestion from wading and swimming |
Dermal contact and ingestion. |
Potentially Exposed: |
Current Future |
Most areas present no current public health hazard. Remedial excavation of selected sections of the FLDD/FLDD Wetland and the East Branch of Greenlaw Brook is designed to mitigate risks. Future sampling will provide data to evaluate remaining risk. |
PCBs - Polychlorinated Biphenyls
PAHs - Polycyclic Aromatic Hydrocarbons
FLDD - Flight Line Drainage Ditch
|
Conclusions and Public Health Action Plan: Wading and Swimming in On-Site Waterways Conclusions:
Actions in Progress:
Planned Actions:
Recommendations:
|
ATSDR concluded that three situations associated with the Loring AFB installation pose no public health hazard: 1) future land use by new occupants; 2) possible migration of on-base contaminants to Limestone Stream to yield concentrations in water of public health concern, and 3) volatile contaminants in the air at the Loring installation.
A. Possible Hazards Associated with Future Use of Former Loring Air Force Base Property Parcels by New Occupants, Prevention Needed
1. Previously Addressed Specific Case: The ATSDR health consultation for LAFB published in January of 1997 found that there was no health-related reason that Parcels B and B-1 to B-7 should not be transferred to the U. S. Department of Labor for use as a contractor-operated Job Corps Training Center.19
2. Specific Current Case: Transfer of Parcels E and E-1 for for recreational use under management by the U. S. Fish and Wildlife Service (Figure 4).
The parcels (E and E-1) proposed for transfer to the United States Fish and Wildlife Service (USFWS) are largely forest and grassland; a number of buildings and IRP sites are also included. Parcel E is on the eastern side of the base and includes the Fire Training Area, Underground Transformer Site, Explosives Ordnance Discharge (EOD) Range, and former Weapons Storage Area. Parcel E-1 is on the western side of the base and contains Landfills 1, 2, and 3. USFWS administrators envision use of the property for hunting, fishing, hiking, mountain biking, auto touring past wildlife habitats, and wintertime cross country skiing.30 Activities would all be daytime events with no overnight camping. The parcels would, insofar as possible, be returned to a natural state, with many of the existing buildings and fences removed over time.
There is the potential for physical hazards from equipment and materials left
in the bunkers of the former Weapons Storage Area and razor wire atop the surrounding
fences. The EOD Range is undergoing sampling and testing to assure acceptably
low levels of explosives or munitions residues in soil. The EOD and ten other
sites will be "safed", which entails the removal of any live munitions that
may have been left behind following munitions practice activities conducted
when LAFB was an active base. ATSDR supports planned stipulations in transfer
documents that, although these areas are considered safe for recreational uses,
incompatible uses, such as construction and digging, will not be allowed.
It is ATSDR's understanding that all drinking water wells and monitoring wells
for which a future need is not identified are to be sealed and abandoned according
to State of Maine standards prior to Air Force transfer of Parcels E and E-1
to USFWS. Also, asbestos in buildings on the parcels is to be removed and properly
disposed. If the asbestos is not removed prior to transfer of the parcels, the
Decision Document should identify and define this environmental issue so that
it may be addressed by the new owners.
|
Conclusion and Public Health Action Plan: Future Use of Parcels E and E-1 for Recreational Purposes under Management by the U. S. Fish and Wildlife Service (USFWS) Conclusion:
Actions in Progress:
Planned Actions:
Recommendations:
|
Figure 4. Main Base Property and Off-Site Parcel IV Limestone Receiver Site - Disposal Parcelization
Levels of contaminants in surface water and sediments of Parcels E and E-1 are low and pose no hazard to persons engaged in recreational pursuits, as shown in Section IC. Fish caught in BB and East Loring Lake contain low levels of DDT and two related compounds that represent no public health hazard at expected rates of fish consumption, as illustrated in Section IA and supported by calculations in Appendix C. The DDT compounds are thought to be due to widespread spraying of DDT for agricultural pest control and not associated with LAFB activities. Fish caught from surface-water bodies within Parcel E-1 are covered by the MDHS advisory. Section IIC (below) demonstrates that air quality basewide represents no public health hazard. Air quality is not an issue on Parcels E and E-1.
3. General Case: Transfer of remaining parcels by deed to new organizations for proposed uses as defined and stipulated in the Record of Decision for the Disposal of Loring AFB, Maine, April 1996.
An Environmental Baseline Survey (EBS) was completed for Loring in 1993. This document assesses the environmental condition of any property to be acquired, transferred, leased, or sold for reuse at a former military base. Subsequent updates called Supplemental EBS (SEBS) reports have been completed for each parcel as it is leased or transferred. An SEBS supports the preparation of a Finding of Suitability to Lease (FOSL) prior to lease execution and a Finding of Suitability to Transfer (FOST) before deed conveyance to organizations other than a federal agency. When a transfer is to be effected to an arm of the federal government, the suitability instrument is called a Decision Document. FOSLs, FOSTs, and Decision Documents must substantiate the nature, magnitude and extent of any environmental contamination for a parcel. They assess any health and safety risks on a property to be leased or transferred and state appropriate restrictions and notifications for the property.
B. Possible Migration of On-Base Contaminants to Limestone Stream to Yield Concentrations in the Limestone Water Supply of Public Health Concern.
Limestone Stream serves as an alternative source of raw water for the Limestone Water District, which supplies potable water to the city of Limestone, Maine. Concerns were expressed in the past by a former employee at Loring Air Force Base (LAFB), that contamination on the eastern side of the base might be migrating to LS and could affect water quality.31
Butterfield Brook (BB) originates north of LAFB and flows southeasterly onto the installation. Willard Brook, a tributary, also originates off-base and joins Butterfield Brook on the LAFB property. BB is dammed to form 40-acre East Loring Lake within the Weapons Storage Area, and then flows southeasterly to join Durepo Brook in forming Durepo Reservoir just to the east of the LAFB boundary (Figure 3). LS, formed by the outflow of Durepo Reservoir, flows south through the city of Limestone to its confluence with the Aroostook River, ten miles from Durepo Reservoir. A portion of the stream flow is diverted as needed to provide Limestone with a backup supply of potable water.
All surface water samples from the BB/LS Study Area, including a "hot spot" sample, gave total carcinogenic risks and total noncarcinogenic risks below MEDEP guidance values and within the USEPA range of acceptable risk. Analysis of surface water in the Durepo Reservoir detected no carcinogenic chemicals of potential concern.32 The noncarcinogenic risk was three orders of magnitude below the threshold of acceptable risk. Since the Durepo Reservoir is located off-site at the downstream end of Butterfield Brook, it is clear that this watershed is not contributing measurable contamination to Limestone Stream by the surface-water pathway.
A final consideration is whether contaminants might be entering LS via the groundwater pathway. Ten groundwater flow fields (FFs) are identified in the LAFB OU12 Remedial Investigation Report33, of which two (FF 10 and FF 5) could influence LS. FF 10 is the larger and more northerly of the two flow fields. The Fire Training Area (FTA) and the Underground Transformer Site (UTS) are potential contributors of contaminants to FF 10 groundwater. Vinyl chloride, benzene, arsenic, TCE, CCl4, phthalates, manganese and iron were detected at low concentrations in various combinations at several sampling sites. Risk assessments that evaluated the groundwater as if it were drinking water yielded total carcinogenic risks of around 1 x 10-4 and noncarcinogenic risk hazard indices of about 15, where a hazard index of one or less indicates no health effect. The values of 1 x 10-4 and 15 are somewhat conservative since the vinyl chloride seemed to be an artifact contributed by the WestbayTM monitoring wells and the phthalates an artifact due to laboratory contamination. Although contributing to risk, the manganese and iron are likely not related to LAFB activities. The most important conclusion of the basewide groundwater flow model for LAFB is that shallow groundwater on the installation discharges primarily to local streams and surface waters.34 Specifically "East Loring Lake and the BB drainage area (includes saturated overburden) are the discharge areas for bedrock and overburden groundwater flowing beneath both sites."35 and " The highest concentrations of contaminants are located in proximity to the source area; contaminant concentrations diminish downgradient from the source area and downward within the aquifer."35 The discharge of groundwater into East Loring Lake and BB has not resulted in measurable concentrations of chemicals of concern in Durepo Reservoir, as seen from the surface water analyses alluded to above. The groundwater flow patterns do not produce contamination in deep groundwater that could adversely impact either Limestone Stream or the Aroostook River.
FF 5 is smaller than FF 10 and is located at the Railroad Maintenance Site. When the groundwater at FF 5 was evaluated for human risk as if it were to be used for drinking water, the risk drivers were vinyl chloride and bis(2-ethylhexyl phthalate), yielding risks in the 1 x 10-5 range. Circumstances suggested strongly that the vinyl chloride result was an artifact due to plastic used in the WestbayTM monitoring well. This compound was not detected in any of the other wells; associated chlorinated parent compounds PCE and TCE were not detected in any wells at the site. The phthalate compound is often found as a laboratory artifact, due to its ubiquity as a plasticizer. If these two compounds are ignored in the risk calculation, the risk of drinking the sampled FF 5 groundwater is less than 1 x 10-6. LS, which flows to within about 1 mile from FF 5, is the likely discharge area for groundwater from FF 5; however, there appears to be no significant contamination of FF 5 groundwater in terms of human health. If contamination existed, concentrations would be diminished greatly before reaching LS. There is a small tributary entering Noyes Lake, south of Noyes Mill Road and west of LS. Analysis of a water sample from this brook in March of 1993 showed no contaminants of concern at levels that would pose a public health hazard.36 Contaminants on base do not migrate to Limestone Stream to yield concentrations of public health concern in the Limestone Water District water supply.
ATSDR prepared a health consultation for LAFB in January 1997 to address several possible exposure pathways, including the air pathway in the vicinity of the FLDD.19 ATSDR concluded in this consultation that the exceedingly low levels of airborne contaminants measured at various points near the FLDD and on adjacent Job Corps campus parcels posed no public health hazard to Job Corps students or employees. The other areas of the installation are further from the FLDD and thus even less impacted than the Job Corps Parcels. Arguments showing that potential air-emission sources due to remediation activity and identified in the health consultation do not represent a public health hazard may be generalized to include all areas of the installation. No other significant sources of air emissions have been identified on base. The low contaminant concentrations in air on the Loring installation pose no public health hazard.
Data included in Reference 19, the January 1997 ATSDR Health Consultation for LAFB,
provides perspective on past exposures at the base to contaminants in air. The 1993 data in the
Air Monitoring Technical Memorandum for Loring AFB37 show an average concentration for
three 8-hour-long monitoring events of 1.82 ppbv for benzene at the FLDD headwall "hotspot".
This value, representative of the worst-case, localized concentration of this risk-driving
compound during a time when LAFB was in operation, is comparable to the 1.80 ppbv daily
median benzene concentration expected as background in suburban areas of the United States38.
Samples taken upwind from the FLDD averaged 0.22 ppbv benzene while downwind samples
registered 0.32 ppbv, both values less than the 0.47 ppbv background level characteristic of rural
America38. The low contaminant concentrations in air believed to have existed at LAFB in the
past represented no public health hazard.
COMMUNITY HEALTH CONCERNS EVALUATION AND
HEALTH OUTCOME DATA
1. At the time of the first ATSDR site visit in 1991 some members of the community expressed concerns that levels of radioactivity existed at Loring that could pose a danger to persons.
Radioactivity associated with storage and maintenance of strategic and conventional weapons at Loring was confined to Operable Unit 1, the Low-Level Radioactive Waste Disposal Sites. These seven sites, designated Areas A through G, were located in the former Weapons Storage Area of Loring Air Force Base. The seven sites include two former low-level radioactive waste disposal trenches and five underground storage tanks (USTs) for low-level radioactive liquid waste. The five radiological USTs were removed in 1994, as were the contents of the two waste trenches. Tests showed no leaking of the tanks and that no significant radioactivity remained after exhumation of the contents of the trenches. All radioactive waste was disposed of off site. Any remaining low levels of radioactivity at Site 1 pose no public health hazard to persons, including those who might visit the OU1 sites.
2. Members of the community asked if it was safe to consume fish from waters on base and off-base water bodies into which they flowed.
As discussed in Section IA of this report, MEDEP, MDHS, and the Air Force, in consultation with USEPA, agreed that a catch-and-release policy with a recommendation of no consumption was appropriate for the Little Madawaska River and its tributaries, including those on former LAFB property, south of the reservoir dam to the point where the LMR passes under Grimes Road. The waters affected are shown in Figure 2 and include streams and impoundments on former LAFB property. Other waters in the area are not affected by the advisory. The concentrations of PCBs in fish necessitate the advisory to protect public health. With removal of most of the PCBs in EBGB sediments by remedial excavation, as existing fish grow old and die new generations will be exposed to greatly reduced concentrations, and PCB levels in fish will diminish. The Base Cleanup Team estimates that the restrictions of the fishing advisory will be reduced and possibly lifted over the next five to ten years.
3. Is on-base contamination migrating to Limestone Stream (an alternate source of public water for Limestone Water and Sewer District)? If so are concentrations of contaminants high enough to affect the health of persons drinking the water?
Possible surface-water and groundwater pathways for transport of contaminants to Limestone Stream are considered in section IIB of this document. Surface-water and groundwater analysis, together with information on groundwater modeling, show that contaminants on base do not migrate to Limestone Stream to yield concentrations of public health concern in the Limestone Water District water supply.
4. A citizen mentioned that it seemed to him a number of persons he knew of on Madawaska Road had cancer. He wondered whether these cancers could be associated in any way with contaminants that had originated on base, particularly in Landfills 2 and 3.
There is no evidence that contaminants from these landfills have migrated the several miles to the area of Madawaska Road. Monitoring wells are located at close intervals in a "picket fence" array to be able to detect and characterize any off-site migration of contaminants in groundwater. A private water well near the LAFB boundary proximate to Landfill 2 is monitored annually and has shown no evidence of contamination. Long-term monitoring of groundwater will continue for at least the next 30 years. No other pathways could transport contaminants from the base to the houses in significant concentrations.
People have strong fears about cancers caused by environmental exposures. It has been estimated that only about 2% of human cancer deaths are attributed to environmental pollution.39 The presence of environmental contamination in a community does not necessarily mean that people are coming into contact with sufficient quantities of hazardous materials to cause disease. Again, we emphasize that it is our opinion that no contaminants from LAFB have migrated to the area of Madawaska Road to make exposure of persons possible.
5. The Environmental Health Director for the Aroostook Band of Micmacs expressed concerns about future exposures of tribal members to possible hazards, including chemical contamination, associated with future use of former Loring Air Force Base parcels slated for transfer to the Micmac Tribe.40 More specifically, he was concerned that certain plant or animal species might uptake or bioaccumulate contaminants at the site to hazardous levels. He asked whether following Tribal cultural practices and food preferences on these parcels (Parcels D and D-1) might pose a public health hazard.
ATSDR is sensitive to the concerns expressed by the Micmac Environmental Health Director and will work with his office and other Micmac authorities to develop a health consultation to identify and evaluate potential exposure pathways. Available environmental data will provide information on identity and concentration of contaminants in soils on the parcels. A search of the literature will yield information from existing studies of bioaccumulation from soil of various contaminants in plant and animal species. For food plants and animals, the major route of human exposure is ingestion. Inhalation of smoke from burning plant materials in cultural and spiritual activities is another route. Dermal contact can also occur. Detailed information on Micmac customs and food preferences can guide the identification of possible specific exposure pathways. These considerations, combined with other information including the geology of the Aroostook County region, should permit evaluation of risks inherent in the specific pathways.
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