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The former Loring Air Force Base (LAFB) property is located in Aroostook County Maine, about two miles northwest of the town of Limestone, eight miles northeast of Caribou, and five miles west of the border of New Brunswick, Canada. The installation covers an area of approximately 9400 acres (14.6 square miles). LAFB closed on September 30, 1994, pursuant to the Defense Base Realignment and Closure Act of 1990 and recommendations of the Defense Base Realignment and Closure (BRAC) Commission. The Air Force Base Conversion Agency (AFBCA) is transferring all property; 58% of the property is being transferred to other federal agencies and 42% of the property to public organizations and non-federal (state and local) government agencies. AFBCA, in concert with the United States Environmental Protection Agency (USEPA) and the Maine Department of Environmental Protection (MEDEP), is coordinating remedial investigations and actions to comply with the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and state solid waste and underground storage tank (UST) requirements. These requirements are to ensure no hazards remain to adversely affect persons or the environment during subsequent use of the property.

Before the currently established environmental regulations, previously accepted hazardous material handling and disposal practices resulted in environmental contamination at various areas on base. As a result, LAFB was included on the USEPA's National Priorities List in February of 1990. The Air Force had conducted an initial assessment of potentially contaminated areas beginning in 1983 and identified a number of Installation Restoration Program (IRP) Sites. There are currently over 50 IRP sites on the Loring property, divided among 15 Operable Units (OUs). Installation-wide investigations and site restorations continue under this program, although much has already been accomplished.

The Agency for Toxic Substances and Disease Registry (ATSDR) evaluated the environmental information at IRP sites within the various OUs and assessed the potential for human exposure in each case. The IRP sites represent no current public health hazard. [Appendix A presents information on ATSDR public health assessment (PHA) hazard categories].


ATSDR concluded that three situations on the Loring installation pose no apparent public health hazard: 1) catching fish from area waters, 2) drinking water from area water wells, and 3) wading and swimming in on-site waterways.

Data available for fish fillets sampled from the Little Madawaska River and certain specific tributaries showed increased carcinogenic and noncarcinogenic risks from eating such fish. As a result the Maine Department of Human Services (MDHS), in consultation with the Air Force, MEDEP, and USEPA, issued a Fish Advisory in April of 1996 warning that no fish from these waters be eaten. This well publicized advisory remains in place to protect the public health.

Widespread, low-level contamination of groundwater on LAFB raised concerns that wells on base and perhaps off base might have become contaminated. However, use of most water wells on base was discontinued in 1960 when the newly completed Madawaska Reservoir water treatment facility was brought on line to supply LAFB's potable water needs. The few water wells that remained in use until base closing in September 1994 serviced small numbers of persons at isolated areas of the base where there was little groundwater contamination. The Madawaska Reservoir facility will continue to serve the needs of the Loring Commerce Centre (LCC). Deed stipulations will restrict construction of new wells by the new owners of transferred Loring parcels. Sampling of nearby off-base water wells at 13 private residences and businesses showed no base-derived contaminants. Periodic, long-term sampling of monitoring wells will guard against the possibility of future contamination of off-base, production, water wells.

Review of Remedial Investigation (RI) data for contaminant concentrations in surface water, sediment, and soil for the Wolverton Brook/Brandy Brook Study Area and the Butterfield Brook/Limestone Stream (BB/LS) Study Area showed acceptable risk to persons wading, swimming, and playing in these watersheds. The lone exception was the Underground Transformer Site Wetland in the latter study area. This site was remediated during 1997 and now poses no apparent public health hazard. In the Greenlaw Brook Study Area all of the following contained contaminants at concentrations that exceeded guidelines: the Flightline Drainage Ditch (FLDD); FLDD Wetland; East Branch, Greenlaw Brook; and Ditches G11 and G12. The BRAC Cleanup Team (BCT), comprised of AFBCA, MEDEP, and USEPA, remediated soil and sediments using future land-use scenarios as described in Section IC. A majority of the excavation work was completed prior to 1998. That remaining was essentially the EBGB downstream of Station 52+00 to the LAFB boundary, which was completed by the end of 1998. Long-term monitoring will follow to assess the effectiveness of the remediation process.


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 1997 ATSDR health consultation, referenced in Section IIA, found no public-health related reasons 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. This transfer has occurred. Similarly, Parcels E and E-1 have been found suitable for transfer to the U. S. Fish and Wildlife Service for recreational use, provided that certain recommended actions are taken before transfer or, alternatively, stipulations are placed in the transfer documents as outlined in the Public Health Action Plan. Considerations for future transfers of parcels are also listed in the Public Health Action Plan.

ATSDR judges that contaminants on base do not migrate to Limestone Stream to yield concentrations of public health concern. Surface water samples from the Butterfield Brook/Limestone Stream Study Area provided data indicating acceptable risks, as defined in the body of this report. Interpretation of groundwater contamination risk data in terms of the basewide groundwater flow model for LAFB shows that this pathway does not contribute significant concentrations of contaminants to Limestone Stream.

The low contaminant concentrations in air on the Loring installation pose no public health hazard. Cessation of flight operations with the closing of LAFB have lowered air concentrations of volatile contaminants attributable to the Flightline Drainage Ditch below levels of concern. No other significant sources of air emissions have been identified on base.


This report is organized by exposure situations. These situations and the areas where they occurred are listed below. Exposure situation is used to describe conditions and circumstances by which people could come in contact with contaminants.

In preparing this public health assessment (PHA), ATSDR relied on the information provided in the referenced documents. ATSDR assumes that adequate quality-assurance and quality-control measures were followed with regard to chain-of-custody, laboratory procedures, and data reporting. The validity of the analyses and conclusions drawn for this PHA are determined by the reliability of the referenced information.

During the environmental investigations at Loring, base personnel and environmental consulting companies under federal contract identified IRP sites from old documents and interviews with past and current employees. Environmental sampling was conducted at those sites where evidence suggested chemical contamination. From these data, from information gathered during our installation visits, and from our visual inspections, we identified a number of situations that suggested the possibility of human exposure. Figure 1 displays locations of IRP sites and other areas discussed with regard to the possibility of human exposure. Appendix B lists the IRP sites with the OUs under which they are grouped to simplify organization and implementation of remedial investigations and actions. Specific areas were designated for residential, recreational, or industrial/commercial uses in the Loring Reuse Plan.1 Any soil or sediment contamination associated with an area was remediated accordingly. Potential exposures fall into the following situational categories:

  1. Catching fish from contaminated waters
  2. Drinking water from off-site or on-site water wells
  3. Wading and swimming in on-site waterways

These possible exposure situations are summarized in Tables 1, 2, and 3; they are discussed in the body of the report. A fourth situation, possible hazards associated with future use of LAFB property parcels; a fifth, possible migration of on-base contaminants to Limestone Stream; and a sixth, on-base air quality; represent no public health hazard.

Figure 1. Sites, Zones, and OUs Under Investigation at Loring AFB


A. Site Description, History, and Demographics

Limestone Air Force Base was activated in February 1953 as a Strategic Air Command base and was manned by the 42nd Bombardment Wing. The installation was located in Aroostook County at the northeastern tip of Maine, occupying about 9,400 acres (14.6 square miles) in the lower Aroostook River Basin and bounded on the north and northwest by the townships of Caswell and Connor, respectively. Renamed Loring Air Force Base (LAFB) in 1954, the base became the home to a series of state-of-the-art bombers and support aircraft. In 1955, the 42nd Air Refueling Squadron was activated. LAFB served as an integral part of the United States air defense system throughout the Cold War. The base was closed in September 1994 under authority of the Base Realignment and Closure (BRAC) legislation. The property that was previously LAFB is now designated the Loring Commerce Centre (LCC). The property has been divided into parcels and is being transferred to other government and commercial organizations under guidelines set forth by BRAC legislation.

As an active U. S. Air Force Base in 1990, Loring had a total population of about 7,800 persons, and a population density of 537 persons per square mile.2 The current (1998) population on the Loring campus is about 1,000 persons (70 persons per square mile) including both those who reside and those who work within its boundaries. This number is expected to grow over the next six or seven years to about 1300 persons as development continues.3

Census Tract 9513 abuts the southwestern portion of the Loring boundary and contains the northeastern portion of the municipality of Caribou. Tract 9516 is contiguous with the southeastern boundary of the installation and contains the town of Limestone. The total population in this area nearby Loring (the sum of the two census tracts) was 6081 persons in 1990 with a population density of 93 persons per square mile. The population of this nearby area was 48.9% male and 96.5% Caucasian. The Native American population was about 70 persons. Approximately 13% of persons were less than 10 years of age and 13% over 65 years old. The number of persons in this nearby area is less in 1998 than in 1990, due primarily to closure of LAFB.2

Census Tract 9501, contiguous with the northern half of the Loring boundary, is large and sparsely populated. In 1990 this 241 square mile tract contained 2,280 persons, or 9.5 per square mile. Males constituted 51% of the population and whites 98.9%. About ten Native Americans lived in this tract. Approximately 12% of persons were under age ten and 13% were over age 65.2

Past waste disposal and storage practices at LAFB have resulted in environmental contamination at multiple sites. Environmental investigations by the Air Force began at Loring in 1983.4 The USEPA added LAFB to the National Priorities List (NPL) in February 1990. Over 50 sites on the Loring installation have been identified for investigation under the Installation Restoration Program (IRP). These sites have been apportioned into 15 Operable Units to simplify and expedite management of remedial actions. Loring AFB was identified by the Congress as a base to be closed under mandated BRAC regulations to facilitate transfer or sale of (1) uncontaminated parcels and (2) previously contaminated but subsequently remediated parcels to appropriate governmental and public organizations. This work is coordinated by the Air Force Base Conversion Agency (AFBCA). A detailed discussion of IRP data and actions is provided in the Loring IRP documents at the Base Conversion Agency Information Repository, 5100 Texas Road, on the Loring facility. This repository is readily available to the public.

B. ATSDR Involvement

The Agency for Toxic Substances and Disease Registry (ATSDR) involvement with LAFB began when Loring was placed on the USEPA NPL. The NPL, also known as the Superfund List, is a tabulation of hazardous waste sites slated for cleanup. ATSDR is mandated to conduct a public health assessment at each site proposed for or listed on the NPL.

ATSDR identifies ways in which people have been, are, or could be exposed to contaminants at an installation and, if such exposure situations are identified, determines whether they represent public health hazards. Determinations described below were based on observations made during site visits in September 1991, July 1994, and August 1997. These included reviews of environmental data and discussions with officials of the Air Force, MEDEP, and USEPA.

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