Fact Sheet #99-07 Time Critical Removal Action for the TCE Groundwater Plume A fact sheet providing information on the cleanup of the TCE and the remaining portion of the SD-5S groundwater plumes. The purpose of this fact sheet is to explain the regulatory process initiated for addressing the trichlorethylene (TCE) groundwater plume emanating from the Massachusetts Military Reservation (MMR). The public will continue to have the opportunity for commenting on the treatment design for cleanup of this groundwater plume.
*November–December 1999, Comment Period *November 1999: Mashpee Selectmen’s Meeting *December, 1999: Public Hearing Words in italics are defined in the glossary on page 3. Background The TCE groundwater plume first was discovered during environmental investigative work performed on Johns Pond during the Winter of 1998. Once the TCE plume was discovered, a separate investigation was started in order to locate the source of this plume and its boundaries. The TCE plume then was mapped westward to the eastern shore of Ashumet Pond. AFCEE, EPA and MassDEP concurred that the source of the TCE plume would be studied further during the investigative work performed for Ashumet Pond during the Summer and Fall of 1999. This work also part of the investigation of the leading edge of Chemical Spill 10 (CS-10) and results of this work will be available during the Spring of 2000. In addition, because of the discovery of the TCE plume, there was concern about implementing the entire SD-5S cleanup remedy. If the entire SD-5S treatment system was installed it might have drawn the TCE plume into an area of lower contaminants, or spread the contaminants. As a result, the northern portions of the SD-5S treatment system were installed and the southern portions were deferred to prevent the potential spread of contamination. Two recirculating wells were installed during the Spring of 1999 and began operating on June 17, 1999. After obtaining additional data, the AFCEE, EPA, and MassDEP determined that a treatment system could be installed to clean up the remaining portion of the SD-5S plume and to clean up the TCE plume. The remedy selected by the AFCEE, EPA, and MassDEP for both plumes is an extraction, treatment, and reinjection (ETR) system. The rates of pumping groundwater from the extraction wells will be balanced to prevent contamination spread of the two plumes. With the implementation of this combined cleanup remedy, both plumes will be cleaned up without negatively affecting Johns Pond. Superfund Response Actions The Superfund regulatory process includes three basic approaches for cleaning up a release of hazardous material: an Emergency Response, a Removal Action, and a Remedial Action. For each type of response there are different processes for addressing the cleanup, different requirements for public involvement, and varying time frames for cleanup. The first and most immediate approach is called an Emergency Response. An Emergency Response is used when an accident has occurred and hazardous materials have been spilled, thereby releasing the materials into the environment and requiring immediate cleanup. The second approach is called a Removal Action. This type of response is used when limited time can be put into designing an efficient way of cleaning up a release. There may be a limited amount of time to design a system based on the types of contaminants identified, their concentrations, and their location. The third type of response action is called a Remedial Action. This is the most common method for cleaning up a release that occurred over a period of time. Most of the groundwater plumes identified on and off the MMR, and on most hazardous waste sites throughout the country, are cleaned up using this approach. It is used when there is no immediate threat. Removal Action Of the three approaches described above, the second approach, removal actions, can be divided further into two types: Time Critical Removal Actions (TCRA) and Non-Time Critical Removal Actions (NTCRA). In the Superfund process, TCRAs are used when cleanup of the release is urgent. TCRAs are used when fewer than six months are available to plan a cleanup and NTCRAs are used when more than six months are available to plan a cleanup. Based on the concentrations of TCE identified in January 1999, representatives from the AFCEE, EPA and MassDEP concluded that there is an urgent need to clean up the TCE plume as a TCRA. This decision was made based on the concentrations of contaminants and their location. Response (Cleanup) Method On June 23, 1999, the AFCEE, EPA, and MassDEP agreed that an ETR system is the preferred design to treat both the TCE and SD-5S groundwater plumes. Three alternatives were considered initially for cleaning up the TCE plume and remaining portion of the SD-5S plume. The three alternatives:
Based on the contaminant concentrations within the TCE plume, recirculating wells were not considered feasible for this project because they would not be as effective as extraction wells. The selected design provides the best balance of advantages and disadvantages of the three alternative designs considered. It uses existing facilities, reduces the possibility of delays to obtain access to property for construction, and is less intrusive to the neighborhood than building a treatment plant in the neighborhood. It also is more cost-effective. Treatment Method: The selected treatment method includes extracting groundwater from two deep extraction wells and piping the water to the existing Sandwich Road Treatment Plant located on-base, near Back Road in Mashpee. The treated water then would be reinjected into the aquifer near the treatment plant through the use of existing reinjection wells (refer to Figure 1). Advantages of the selected treatment method include:
Open cut trenches will be used for pipeline installation. The estimated cost of the selected treatment method is $4.7 million.
Public Involvement Due to the urgent nature of the cleanup action, public involvement requirements for a TCRA include a formal comment period after construction activities begin. However, based on the high level of public interest in communities around Johns Pond, opportunities for public comment were made available by AFCEE before construction work starts in September 1999. A public informational meeting was held on June 15, 1999 along with a public hearing on August 11 with the Mashpee Selectmen. Additionally, AFCEE will continue an ongoing public involvement effort to ensure that the public is kept informed and has an opportunity to provide comment on this removal action. Particular efforts will be made to involve residents living near and around Johns Pond. AFCEE, EPA, and MassDEP encourage residents to attend citizen team meetings (e.g. Joint Process Action Team, Public Information Team, and Senior Management Board) and public meetings. The following times have been set for discussing this cleanup work with the public:
What Do You Think? AFCEE, EPA, and MassDEP are interested in hearing comments on the cleanup work. Please call or send comments to the address and phone numbers provided below. AFCEE will schedule a formal comment period on the Administrative Record for the TCE plume in Fall 1999. You do not need to be a technical expert to comment. There are several ways to submit a public comment:
Glossary extraction, treatment, and reinjection (ETR): a system that extracts groundwater, treats it to reduce or eliminate contaminants, and reinjects the treated water into the aquifer. groundwater plume: a body of groundwater containing contaminants that exceed federal and state drinking water levels or other risk-based levels at multiple test well locations. trichloroethylene (TCE): a solvent used to dissolve or disperse another substance such as oil; used in metal degreasing. time-critical removal action (TCRA): an expedited regulatory approach used when quick actions are needed to clean up a hazardous material release. For More Information Doug Karson, Community Involvement Specialist Jim Murphy, Community Relations Coordinator Ellie Grillo, Community Involvement Coordinator
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