Thoughts and Opinions
Below you can read thoughts and opinions posted by BACSE members on pertinent issues.
*Groundwater Contamination and Its Significance for the Future*
Submitted by BACSE members 7/28/2009
Those of you who have been following environmental activities at NAS Brunswick have likely heard of the Eastern Plume, a large area of soil and groundwater contamination near the eastern boundary of the base property. You might wonder how groundwater becomes contaminated.
It starts with seepage from a source. Chemicals dumped or spilled on the ground surface or buried in the ground sink downward into the soil. Infiltration of rainwater can also wash pollutants downward into the ground. Eventually the contaminants sink until they reach the surface of groundwater, also known as the water table. The contamination is then spread further as it moves with the groundwater flows. Groundwater can eventually discharge at the ground surface in the form of a spring, and can also feed into streams and rivers.
Understandably, the Eastern Plume has certainly gotten the lion’s share of attention over the years. Investigations during the late 1980’s identified the large area of groundwater contaminated by solvents and other compounds extending east and southeast of the Fire Training Area (Site 11), the Defense Reutilization Marketing Office (Site 13), and the acid/caustic pit at Building 584 (Site 4). In the early 1990’s, computer modeling of groundwater flow rates indicated that this plume of polluted groundwater could start discharging to the Harpswell Cove estuary in as little as five years. As a result, the Navy installed a groundwater treatment system that is still operating today.
However, recent investigations has identified “hot spots” of high contamination concentrations and new contaminants that were not being affected by the treatment. The Navy recently completed plans to improve treatment.
It has been estimated that it will take between 20 to 70 years to reach cleanup goals and restore the aquifer to federal drinking water standards.
But for all the attention focused on the Eastern Plume, it is important to remember there are several other groundwater contamination plumes identified on-base. The materials buried in landfills at Sites 1, 2, and 3 still have the potential to leach into groundwater. All three landfills are located southeast of the end of the runways adjacent to Mere Brook.
In the instance of the old Acid Caustic Pit, or Site7, the contaminants of concern in groundwater are metals. The site is located in the “Gateway” area near the northern end of the base that is now a primary focus for redevelopment. The Navy is currently undertaking remedial measures.
Site 9, the Neptune Drive Disposal Site, encompasses about 20 acres in the central part of the base that includes a former incinerator site and landfill and waste disposal area. The source of the solvent contamination detected in groundwater at the site has never been clearly identified. Over the last couple of years, the Navy has excavated a large area of buried ash, and filled it back in with clean soil.
Gasoline leaks at the NEX gas station, also located near the center of the base, contaminated a large volume of soil and produced a plume of dissolved gasoline-related chemicals in the groundwater flowing southward from the site. The Navy is now undertake a large-scale contaminated soil removal action and will then determine what additional action is required for groundwater remediation. The potential for vapors emanating from the ground into buildings adjacent to the site must also be checked.
The tanks and piping at the Old Navy Fuel Farm, located near the northern end of the runways, were removed a number of years ago along with a significant volume of contaminated soil. However, there remains a plume of petroleum-contaminated groundwater that is migrating slowly toward the south.
In addition, there are locations that the Navy is only now beginning to investigate where groundwater contamination may be discovered. An example is the Quarry Site in the western portion of the base that is being evaluated under the Navy’s former munitions sites program. The historical records search and recent initial site screening indicate a strong potential for soil and groundwater contamination. Field investigations have yet to be conducted.
Protecting of the public is not limited to preventing the use of groundwater on-base. The depth to groundwater (to the water table) varies around the base, but in some places is shallow enough that an excavation will end up with water in the bottom. If this water is polluted, then workers at the excavation site could be exposed to the chemicals if they come in contact with the water. There must be controls in place that will prevent the risk of human exposure to contaminated groundwater in this manner. For some chemicals, there may also be potential risk from vapors to workers, as well as to occupants in a building constructed at that location.