Fact Sheet #99-03 Fuel Spill-1 Source Area and Groundwater Plume The purpose of this fact sheet is to provide background on the Fuel Spill-1 (FS-1) source area and groundwater plume. After public input this coming summer, project managers from the Air Force Center for Environmental Excellence (AFCEE), the U.S. Environmental Protection Agency (EPA), and the Massachusetts Department of Environmental Protection (DEP) will evaluate several alternatives to recommend the most appropriate cleanup solution for this study area and groundwater plume. A related operation called the Quashnet River/Bog Separation Project Pilot Test is already underway to accelerate cleanup. Startup of the pilot system is scheduled for April. Words that appear in italics are defined in the glossary at the end of this fact sheet. Source Area The source of the FS-1 groundwater plume is the Aviation Gas (AVGAS) Fuel Valve Test Dump Site in the eastern part of the base near the runways and within the flight line. The site was used from 1955 to 1970 to test fuel dump valves on EC-121 Super Constellation aircraft. As part of the tests, fuel was released onto the ground. Fuel constituents degraded naturally, however, a fuel additive, ethylene dibromide (EDB) was more persistent and migrated into the groundwater forming a plume. The baseline risk assessment in the Remedial Investigation Report concluded that there were no risks from exposure to surface soils in the source area. FS-1 Groundwater Plume The FS-1 groundwater plume extends southeast from the base in the town of Mashpee, northeast of Johns Pond (see map). It is 7800 feet long and up to 1200 feet wide. The plume averages 100 feet thick beginning approximately 100 feet below the ground surface and is detached from the source area. The southern extent of groundwater contamination appears to be just north of a small fork in the Quashnet River where the groundwater plume rises and enters the river. Surface water contamination has been detected in the Quashnet River approximately 3000 feet south of Route 151.
What is a Plume? A groundwater plume is a body of groundwater containing contaminants exceeding federal and state drinking water levels at multiple well locations. Contaminated water can result when fuels, solvents, or other potential contaminants are spilled or released on the ground. When these materials filter through the sandy Cape Cod soil, they encounter groundwater, or the water table, where the soil is saturated with water. As the groundwater moves, the contaminants may dissolve and be carried with it, creating a groundwater plume. Primary Contaminant The primary contaminant of the FS-1 groundwater plume is EDB, which is a probable human carcinogen. EDB was added to leaded gasoline, including AVGAS, to inhibit the build-up of lead in engines. To date, the highest concentration of EDB found in the groundwater was 10 parts per billion (ppb). The Massachusetts drinking water standard for EDB is 0.02 ppb. The highest concentration found in the surface water is 1.4 ppb. The Remedial Investigation Report concluded potential risks from exposure to groundwater and surface water. Feasibility Study AFCEE has analyzed alternatives for treating the plume, which are presented in the draft Feasibility Study report issued on February 19, 1999 to the regulatory agencies. A Proposed Plan, which is based on the potential cleanup alternatives identified and screened in the Feasibility Study, will be issued in June. The Proposed Plan will describe AFCEE’s preferred alternative for cleanup activities along with other alternatives evaluated. Each alternative included in the Proposed Plan is detailed more fully in the Feasibility Study. Pilot Test To reduce and contain contamination at the leading edge of the plume on an expedited basis, AFCEE has accelerated a portion of the cleanup under a pilot test. This pilot test will be consistent with the long term final remedy for the plume and it should reduce potential risk from exposure to contaminated surface water and make the cranberry bogs ready for production by the year 2000. The plan is to: extract contaminated groundwater from a deep well and shallow groundwater extraction wells; treat water by granular activated carbon treatment; release the treated water to surface water and shallow reinjection points; and physically separate bogs from EDB contaminated surface water by constructing earthen berms. AFCEE obtained feedback on this pilot test from the general public and concurrence of EPA and MassDEP regulators and other stakeholders including, the Massachusetts Department of Fisheries, the Mashpee Conservation Commission, cranberry growers and others. Opportunities for Community Involvement The Remedial Investigation and Feasibility Study will be available for public review. It has been discussed at citizen advisory team meetings. The results of the Feasibility Study were presented at the February 24 Joint Process Action Team meeting and also will be presented and discussed at additional citizen team meetings. The Proposed Plan is scheduled for release in early June and will be followed by a 30 day public comment period including a public information meeting and a public hearing. The Proposed Plan is a summary of the advantages and disadvantages of various alternatives for cleanup, and a discussion of the alternative preferred by AFCEE. Next Steps The following is a listing of activities and public input events currently anticipated relative to the FS-1 plume:
AFCEE will also make presentations to solicit comment from the Mashpee Selectmen and Mashpee Conservation Commission. Project managers and community involvement representatives are available to speak to other groups by request. For More Information More detailed information regarding the FS-1 groundwater plume is available for review at the main libraries in Sandwich, Bourne, Mashpee, and Falmouth, at the U.S. Coast Guard library on base, and at the Installation Restoration Program office. For additional information, visit our website at http://www.mmr.org or call our Community Involvement Office at (508) 968-4678. For further information, please contact: Doug Karson Jim Murphy Ellie Grillo GLOSSARY Aviation Gas (AVGAS): fuel for jet engines. ethylene dibromide (EDB): an additive in aviation gas to control the build-up of lead in the engines. Feasibility Study (FS): a report that identifies and screens potential cleanup alternatives for a site that requires further remedial action. groundwater plume: a body of groundwater containing contaminants exceeding maximum contaminant levels as defined by multiple wells. In the absence of maximum contaminant levels, a risk-based level will be established. parts per billion: an expression of concentration of contaminants, also seen as micrograms per liter in water. Proposed Plan (PP): a document that summarizes for the public the preferred remedial action for a site and presents the rationale for the preference. Record of Decision (ROD): a document presenting the remedial action selected under agreement with the regulatory agencies. Remedial Investigation (RI): an investigation to gather and analyze the data necessary to determine the nature and extent of contamination at a site, and to provide information for identifying and evaluating options for remedial action.
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