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The former Loring Air Force Base is located in the town of Limestone in northern Aroostook County, Maine.

In April 1947, the U.S. Army initiated a directive authorizing land acquisition and construction of Limestone Army Air Field. Before the base was developed, the area primarily consisted of forested lands and farmlands. With the creation of the U.S. Air Force as an independent agency in September 1947, it was established that, once operational, the base would transfer to the U.S. Air Force. The construction period lasted until February 1953. Loring Air Force Base became home to the 42nd Bombardment Wing.

The base was one of the first to be designed and built to accommodate high-speed aircraft, and its layout was different from older, converted Army posts. Many of the industrial, flying and military activities at Loring Air Force Base required the storage and handling of hazardous materials. Several maintenance hangars and aircraft maintenance shops were used almost continuously from 1952 until the base’s closure in 1994. These operations included the maintenance of jet engines, avionic components and vehicles. These industrial operations generated waste oils, recoverable fuels, spent solvents and cleaners.

EPA added the site to the National Priorities List in 1990 due to contamination from waste oils, fuels cleaned from aircraft and vehicles, spent solvents, polychlorinated biphenyls (PCBs), pesticides and three on-site landfills.  The facility officially closed in September 1994 under the Defense Base Realignment and Closure Act of 1991. Wastes generated by the U.S. Air Force when the facility was an active military installation contaminated soil, groundwater, surface water and sediment at a number of areas across the former base. Despite its closure as an active base, the Air Force is doing the cleanup needed until cleanup goals have been achieved.

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What Has Been Done to Clean Up the Site?

The site is being addressed through federal actions. Since the site’s listing on the NPL, direct contact threats on the base have been eliminated through numerous Air Force cleanup actions. Long-term environmental monitoring continues at many of the sites where cleanup actions have been taken.

Cleanup work addressed the following areas:

Former Weapons Storage Area: Disposal trenches containing some 1,000 cubic yards of low-level radioactive waste from early-era nuclear weapons maintenance operations were removed and shipped by train to a licensed disposal facility in Utah.

Landfills 2 & 3: The 1994 cleanup plan required the construction of an impermeable cap over each of these two former landfills, which together covered 27 acres. Landfill 2 was capped in the summer of 1996 and Landfill 3 was capped in 1999.

Landfill 1 and Former Coal Yard: Landfill 1 was closed in accordance with state regulations because no Superfund wastes were identified at the landfill. About 180,000 cubic yards of waste from the Coal Ash Yard were excavated and consolidated into Landfill 3 before it was capped.

Debris Disposal Areas: After 17 former disposal areas across the base were evaluated, the only required cleanup was at the Contract Storage Shed site. An excavation and capping was completed there in the summer of 1997. In 2013, a re-evaluation of the site was completed to determine whether existing soil conditions were suitable for unlimited use and unrestricted exposure.  This re-evaluation showed that site soil does not pose an unacceptable risk for residential use and that land use controls (LUCs) were no longer necessary to protect human health.

Landfills Groundwater: Groundwater studies at the former base landfills concluded that no further cleanup was required for groundwater beneath Chapman Pit and Landfill 1. Routine groundwater monitoring for Landfills 2 and 3 continues to be conducted to confirm the long-term effectiveness of the caps.

Railroad Maintenance Shop: About 200 cubic yards of contaminated soil was originally going to be excavated and shipped off base for disposal. The remedy was revised and the material was consolidated into Landfills 2 and 3 before they were capped.

Former Quarry: In the summer of 1995, 80,000 cubic yards of sediment and soil were excavated and consolidated in Landfills 2 and 3.

Various Removal Action Areas: About 30,000 cubic yards of contaminated soil were excavated and placed in Landfills 2 and 3 before they were capped. In 2013, the cleanup plans for the former Loring AFB jet engine buildup shop (JEBS) and former jet engine test cell (FJETC) were modified to include the excavation and on-base treatment of residual contaminated soils that remained above cleanup levels after undergoing in-situ soil vapor extraction and bio-venting, repsectively. Excavation and sucessful treatment of these soils by landspreading was completed in 2013.

Base-wide Surface Water and Sediments: Contamination studies included three major watersheds encompassing the former base. Of the 30 square miles studied, only the on-base portion of the East Branch of Greenlaw Brook required cleanup. More than 150,000 cubic yards of contaminated sediments along a 2.25-mile reach of the brook were excavated and placed in Landfill 3 before it was capped. The sediment removal and stream restoration finished in 1998. The Air Force continues to collect surface water, sediment, and fish contaminant levels to assess the effectiveness of the sediment cleanup. 

Base-wide Groundwater: The cleanup plan for base-wide groundwater was completed in September 1999 and focused on about 2,000 acres in the industrial area of the former base. Cleanup included institutional controls within defined groundwater management zones (GMZ) to prevent uncontrolled use and consumption of groundwater, provisional water supplies, long-term groundwater quality monitoring, five-year reviews, and groundwater management zones.

  • GMZ 1 - In 2013 and 2014, the Air Force implemented remedial pilot studies to evaluate the effectiveness of in-situ bioremediation of bedrock groundwater contamination associated with the former Jet Engine Buildup Shop. A mixture vegetable oil and microbes capable of degrading VOCs were applied into contaminated groundwater zones. Groundwater data collected as part of this study is being evaluated by the Air Force to determine the effectiveness of the bioremediation pilot study.
  • GMZ 3 - In 2014, the portion of the orignal base-wide groundwater cleanup plan was revised to include the implementation of in-situ bioremediation of VOC-contaminated groundwater associated with a former Air Force industrial building (Building 8711).  Vegetable oil and microbes capable to degrading VOCs were injected into the contaminated bedrock zone. Groundwater data collected as part of this revised cleanup plan is being evaluated by the Air Force to determine the effectiveness of the remedy.
  • GMZ 4 - Innovative treatment technology pilot studies have been underway at the former Quarry site since the early-2000s to evaluate the effectiveness of removing and degrading VOC contamination within the groundwater-bearing bedrock zone at the site. In 2002, a steam injection and vapor extraction pilot study was initiated within these bedrock zones to in an effort to remove VOC contamination.  While some VOC contamination was extracted from the bedrock zones, the effectiveness of the technology was limited by the complexity of subsurface conditions at the site. In late 2014, the Air Force initated another technology demonstration study to evaluate enhanced in-situ bioremediation to treat VOC contamination within the fractured bedrock zones. Data collected as part of this study is being evaluated by the Air Force to determine the effectiveness of bioremediation.
  • GMZ 5 - In 2014, the portion of the orignal base-wide groundwater cleanup plan was revised to include the excavation and on-base landspreading treatment of residual petroleum- and VOC-contaminated soils that existed below the water table at the former jet engine test cell (FJETC). The contaminated soil was excavated, successfully treated and returned to the site in 2015. In 2017, the Air Force also implemented a pilot study designed to evaluate the effectiveness of in-situ bioremediation to treat VOC-contaminated bedrock groundwater. Groundwater data collected as part of this pilot study is being evaluated by the Air Force to determine the effectiveness of the pilot study.
  • GMZ 6 - Since 2014, the Air Force has been evaluating the treatment of residual fuel-related contamination at the former Loring AFB fire training area. To accelerate the in-situ degradation of this contamination, the Air Force is injecting air into the fractured bedrock where the contamination is located. The pilot cleanup system has been expanded as data continues to be collected to assess cleanup progress.

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What Is the Current Site Status?

The Maine Department of Environmental Protection and EPA each have assigned roles for overseeing the Air Force's cleanup at the former base’s roughly 9,000 acres. All removal and remedial decisions have been made for the 54 sites identified on the former base. All Superfund design and construction activities have also been completed. Operation and maintenance and long-term monitoring activities are being conducted by the Air Force.

Routine groundwater quality monitoring by the Air Force makes sure groundwater contaminant plumes are not migrating and the expected reductions in contaminant concentrations are occurring.

The Air Force has conducted a preliminary assessment to identify of areas on the former base where firefighting foams were historically stored and used that contained for poly- and perfluoroalkyl substances (PFAS), specifically the emerging contaminants perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA). Air Force sampling of public and private drinking water supplies near the former base have confirmed these chemicals have not negatively impacted these sources.  Groundwater, surface water, soil and sediment samples collected on the former base as part of initial site investigation activities have identified the presence of these chemicals. Future PFAS studies are planned.

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Activity and Use Limitations

At this site, activity and use limitations that EPA calls institutional controls are in place. Institutional controls play an important role in site remedies because they reduce exposure to contamination by limiting land or resource use. They also guide human behavior. For instance, zoning restrictions prevent land uses – such as residential uses – that are not consistent with the level of cleanup.

For more background, see Institutional Controls.

Institutional controls are required for this site.

This site requires ICs because a decision document, such as a Record of Decision, has documented some level of contamination and/or remedy component at the site that would restrict use of the site. These ICs are required to help ensure the site is used in an appropriate way and that activities at the site do not damage the cleanup components. These ICs will remain in place for as long as the contamination and/or cleanup components stay on site. The site contacts should be consulted if there are questions on the ICs for this site.
The following IC Instruments provide media-specific use restrictions that have been implemented by EPA for protecting human health, the environment and remedial engineering on this site. Instruments are documents used by EPA or other organizations to implement the use restrictions at a site. To know about other media-specific use restrictions that are planned but not implemented at this site, please contact the Regional Office using the Site Contact listed above.
Click here for IC Instruments implemented for this site.

To contact EPA regarding Institutional Controls and/or activity and use limitations, please complete this form.

ICs are generally defined as administrative and legal tools that do not involve construction or physically changing the site. Common examples of ICs include site use and excavation restrictions put in place through State and local authorities like zoning, permits and easements. ICs are normally used when waste is left onsite and when there is a limit to the activities that can safely take place at the site (i.e., the site cannot support unlimited use and unrestricted exposure) and/or when cleanup components of the remedy remains onsite (e.g., landfill caps, pumping equipment or pipelines). Effective ICs help ensure that these sites can be returned to safe and beneficial use.
Disclaimer: This information is being provided by EPA as an informational tool to further assist the public in determining the types of restrictions that may be in place at National Priorities List sites being addressed by EPA under the Superfund program. In addition to the areas addressed by the institutional controls identified on this web site there may be other areas on the property that require restrictions on use of the property that are not captured in this EPA database. States and other entities may have implemented laws or restrictions applicable to this site. The information provided herein does not replace a title search or meet "All Appropriate Inquiry" requirements. U.S. EPA encourages users to review the Site files to obtain information regarding remedy components, containment systems and the land use for which cleanup standards were selected for these sites. More information and links can be found in the Institutional Control instrument collection of document, above, and the EPA regional offices may also be contacted.

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