Public Briefing on the Remedy
Welcome and Introduction: Mr. Field convened the meeting at 5:40 P.M. He gave a brief history of himself and his organization Consensus Building Institute (CBI), and welcomed everyone to the meeting. Mr. Field stated that the first remedial alternative for the plumes would be announced. He commended the people involved in the process, for their hard work. Mr. Field introduced the members of the panel, Mr. Jim Snyder of Air Force Center for Environmental Excellence (AFCEE), Mr. Paul Marchessault of the United States Environmental Protection Agency (USEPA) and Mr. Len Pinaud of Massachusetts Departmetn of Environmental Protection (MADEP). Mr. Field briefly discussed the Decision Criteria Matrix Process, to help explain how tonight’s decision was reached. He went over the agenda and the ground rules, and then introduced Mr. Snyder. Description of Recommended Alternative for Cleanup: Mr. Snyder explained the selected alternative and how they reached their decision. He stated that they preferred the alternative with the best balance, of the following factors:
Mr. Snyder stated that they chose alternative B, with refinements. He stated that some favored aspects from alternatives C, C 1, and F were combined with alternative B. Mr. Snyder explained that alternative B includes three sections of extraction and reinjection fence, continued operation of the existing recirculating well in the area of high concentration, and potential remedial action to improve mass capture and the amounts entering the silts. Mr. Snyder stated the importance of the Sandwich Road fence, in that it alone captures 50% of the plume mass. Mr. Snyder stated that the Sandwich Road fence will capture the mass of contaminants at and just north of Sandwich Road in an expedited fashion. This, in turn, will protect Ashumet Valley Pond and the Horseshoe Bend neighborhood. He stated that the southwest extraction (ETR) fence protects the aquifer southwest of the plume including Falmouth’s proposed Crooked Pond Well. Mr. Snyder stated that the southern ETR fence will protect existing and future water supplies south of the CS-10 plume. He stated that the Air Force (AFCEE) had concerns about whether this portion of the aquifer will be useable in the foreseeable future because of the other plumes. Mr. Snyder stated that AFCEE will continue to evaluate what is downgradient and the usability of the aquifer, and answer that question the best they can. Mr. Snyder then stated the rationale behind the selection of alternative B. (See attached) Mr. Snyder turned it over to Mr. Marchessault for the "Refinements" portion of the presentation. (See attached) Mr. Marchessault stated the four overall goals of the proposed refinements to the "hot spot" of CS-10 as:
Mr. Marchessault stated that Refinement #1 includes gathering more information on the silts and evaluating the plumes activities. He stated that in addition they will be evaluating in plume actions which will reduce the mass going into the silts, as well as reduce the mass before it gets to the extraction, treatment, and reinjection centers. Mr. Marchessault stated that another goal of this refinement includes minimizing hydrological impacts to the aquifer, and improving overall system performance. Mr. Marchessault stated that in Refinement #2, the recirculating wells that are currently operating will continue to operate at least until the Sandwich Road well fence has been installed. Mr. Pinaud was introduced to discuss the southeast Sandwich Road extraction fence, north of Ashumet Pond. Mr. Pinaud stated that the project managers evaluated the benefits and disadvantages of wells in this area and the following factors were taken into consideration:
Mr. Pinaud stated that, based on those factors, they are recommending that wells not be installed in the area south of Sandwich Road and north of Ashumet Pond. He stated that there is less than 2% mass of the plume in this area. Mr. Pinaud also stated that data they evaluated shows the plume in this area is underflowing Ashumet Pond. He also stated that the extraction fences had too great of an impact on the ecological areas. Mr. Pinaud stated that MassDEP recommended a continued investigation of the area between Ashumet and Johns Pond as well as east of Johns Pond. He also stated that based on that investigation, a recommendation will be made for future remedial action in that area. Mr. Pinaud stated that this was part of the execution plan which is due on September 16, 1997. Mr. Snyder stated that the following were other considerations with this alternative:
Questions and Answers: Mr. Field stated the ground rules for the Question and Answer part of the presentation. Mr. Cambareri stated that he thinks the decision on CS-10 was a very important and difficult one to make.. He stated that he felt the decision was a good one and a balanced one as well. Mr. Cambareri feels that it meets public concerns as well as the need for better source reduction. Ms. Valiela congratulated them on a job well done. She stated that it clearly was a balance of the various types of input that she had heard. Ms. Valiela then asked about the expedition of construction of the Sandwich Road fence. Mr. Snyder stated that it was a fairly short extraction fence, construction is on base property and should be very straight forward. He stated that the part of the process could be in place in twelve months. Mr. Kinney stated that he felt it was a pretty good alternative. He stated his concern for the lack of recirculating wells around Ashumet Pond. Mr. Kinney asked if they would only not capture about two percent of the mass by not having those recirculating wells. Mr. Snyder stated that that was correct. Mr. Kinney asked what the plans were to put recirculating wells, or more extraction fences, to fill out the circled area of high concentration, also referred to as a "hot spot". He also asked about expedited plans to investigate the other side of Johns Pond and in-between the two ponds. Mr. Snyder stated that in the area south of Sandwich Road they are finding what they believe to be the leading edge of CS-10. He stated that the wells located there, were not taking any mass down in that area. Mr. Snyder stated that, they felt it was not worth putting the neighborhood through the construction and deconstruction, within such a short period of time. Mr. Snyder stated that they are still formulating an approach for the area of high concentration. He stated that they preferred a less aggressive alternative to avoid the silts, and improve the life cycle of part of the fence. Mr. Kinney asked what the schedule was for the next two parts. Mr. Snyder stated that that is the next phase, and it is due soon. Mr. Martin, President of the Ashumet Valley Property Owners Association, asked what the depth of CS-10 plume was, where it abuts the pond. Mr. Smith stated that it was 50 feet deep along the shoreline. Mr. Martin stated that parts of Ashumet Pond are 65 feet deep and asked if the plume was entering the pond at that depth. Mr. Smith stated that it was possible and they are currently investigating that. Mr. Martin asked if anyone has investigated at that depth. Mr. Snyder stated that they have gone off shore, and the deeper areas discharge south of the pond. Mr. Smith added that it is likely that it is not entering due to the recharge of water from the pond at that side. He stated that they will look at that as part of the pond study. Ms. Valiela asked how many gallons would be pumped per day with this option, and what the capital costs were. Mr. Snyder replied that 6.9 million gallons would be pumped per day. He also stated that the capital cost would be $39 million to build and $4 million to operate and maintain. Mr. Kinney asked about what would be done on the other side of the pond, and how aggressive the investigating would be. Mr. Marchessault stated that they have installed fifteen wells in-between the ponds thus far. He also stated that they feel they have a good handle on the eastern boundary of CS-10. Mr. Marchessault stated that one of the discussions they had was to ensure that there would be an aggressive schedule and continued investigation of that area. He also stated that they would propose remedial action as part of the execution plan in September. Mr. Kinney asked again about the reparations to the property owners. Mr. Snyder stated that the only reparations they are proceeding with are leasing for access to property. Final Comments: Mr. Snyder stated that he felt this alternative was a good one and it has potential. He also stated that this was an interesting process. Mr. Field displayed the petition for CS-10 slide from the presentation. He pointed out that at the top of the slide were three different logos, the Department of Defense (DOD), the United States Environmental Protection Agency (USEPA), and the Commonwealth of Massachusetts. He congratulated the public, the Joint Process Action Team (JPAT), the PIT and everyone from the agencies who worked so hard to get to this plan. Mr. Field thanked everyone for attending and adjourned the meeting at 7:30 P.M.
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