Ashumet Valley Posterboard Session and Presentation
Unitarian Universalist Church
August 19, 1997
3:30 P.M. - 9:00 P.M.

Agenda Item #1: Welcome, Introductions, Groundrules:

Mr. Sobel convened the meeting at 6:40 P.M. and introduced himself and his company, Consensus Building Institute (CBI). Mr. Sobel stated that the goal of the meeting was to have the remedial project managers (RPM’s) explain the alternatives and answer questions or concerns from the community. He reminded everyone that the meeting was recorded and summarized, and the summary would be made available to the public. Mr. Sobel stated that September 2, 1997 was the deadline for submitting written comments.

Mr. Sobel introduced the panel of RPM’s, and invited anyone in the audience who was involved in the cleanup, to introduce themselves. Ms. Hunter from the Environmental Protection Agency (EPA) asked the audience to please introduce themselves to either herself or Mr. Karson, and suggest any better way the EPA could reach out to the public. Ms. Valiela from the Falmouth Board of Selectmen introduced herself. Dr. Price from the Falmouth Board of Health introduced himself. Ms. Brand from CH2MHILL introduced herself and brought attention to two of the handouts. The first handout was "We Need Your Help" designed to encourage the public to get involved, and the other was an evaluation form on the presentation.

Mr. Karson asked that anyone who attended the meeting because of the signs posted, raise their hand. He then counted eight people who were there because of the signs.

Mr. Sobel asked the people in the audience who were members of any of the Process Action Teams to please identify themselves by standing. Mr. Sobel clarified that the members of the EPA and MassDEP on the panel were not making presentations, they were there to answer any questions the audience may have had. He then introduced Mr. Snyder for the first part of the presentation.

Agenda Item #2: What is groundwater? What is Risk?:

Mr. Snyder explained the process of how water from rain and snow percolate through the ground, and into the water table. Mr. Snyder stated that in regard to the Ashumet Valley area, there is a source of contamination on the surface, which enters into the process. He stated that the contaminants enter the water system, and travel with the water flow, forced by gravity.

Mr. Snyder displayed a slide of the Sagamore Lens. He defined a lens as a separate water body of drinking quality water. Mr. Snyder pointed out the location of the MMR and stated that it was on the highest elevation of the Sagamore Lens. He stated that consequently the contaminants migrate downhill forced by gravity.

Mr. Snyder stated that the Ashumet Valley plume originated at the former fire training area, and Massachusetts Military Reservation (MMR) sewage treatment plant. He displayed slides of the source areas, to show the progress of the remediation.

Mr. Snyder stated that part of the Decision Criteria Matrix talks about risk and risk assessment associated with the plume. He explained that the risk assessment is a way to look at the chemicals in the plume, where the exposures were, and what levels they were at, to estimate the risk. Mr. Snyder stated that part of the process was to understand who and what was being exposed, and how the exposure is happening. He stated that toxicity assessment was also a part of the process. Mr. Snyder stated that these factors are measured against the receptor, human or ecological, to determine the risk, and in turn, what the priorities are. Mr. Snyder stated that there had to be a complete pathway from source to receptor. Mr. Snyder stated that they evaluate human health risk as well as risk to ecological receptors. Mr. Snyder displayed a graph to show the acceptable levels of human and ecological risk in relation to the alternatives. Mr. Snyder turned the presentation over to Mr. Smith.

Agenda Item #3: Ashumet Valley Groundwater Plume:

Mr. Smith displayed an aerial photograph of the Ashumet Valley plume. He pointed out Ashumet Valley, Hayway Rd., Falmouth Conservation Wetland, and other landmarks as points of reference. Mr. Smith stated that the plume contained organic constituents, including trichloroethylene (TCE) and tetrachlorethylene (PCE). Mr. Smith stated that those constituents were probably primarily associated with the fire training area. He stated that they were common organic solvents used by the Air Force. Mr. Smith referred to a posterboard of the plume and stated that the outline showed the five parts per billion (PPB) contour. He stated that within that zone, based on the monitoring data, the concentrations exceed five MPL. Mr. Smith stated that they drew the plume to enclose any values that exceed five PPB, which is the drinking water standard for TCE and PCE.

Mr. Smith stated that the plume also contains inorganic constituents. He stated that they included metals, nitrates, phosphates, and phosphorous. Mr. Smith stated that the inorganic constituents are associated with the MMR sewage treatment plant. He also stated that they are common compounds found in nutrient fertilizer, and any septage fields in the area.

Mr. Smith displayed a slide depicting the entrainment of the organic constituents and the inorganic constituents in the plume. Mr. Smith pointed out the area with levels of nitrate. He stated that the drinking water standard for nitrate was about 10 PPB. Mr. Smith also pointed out the area of critical concern, from an exposure standpoint. Mr. Smith pointed out the area of the plume containing phosphorous. He stated that the danger with those nutrients entering the pond, was eutrofication of the pond. Mr. Smith stated that eutrofication occurs when nutrients, introduced to ponds through septic fields, for example, result in an algae bloom. The water conditions become anoxic and it kills off the other biota that live there. Mr. Sobel asked Mr. Smith to define the term entrainment. Mr. Smith stated that both plumes come from the same source, they move together, but there is some difference in the movement because they travel at slightly different rates.

Mr. Sobel encouraged the audience to write questions down, and stated that ample time would be allotted at the end of the presentation, to answer them.

Mr. Snyder explained the technologies being used in the alternatives. He stated that all the alternatives represent some combination of these two technologies: extraction, treatment and reinjection (ETR), and recirculating wells. *See attached

Mr. Smith stated that the following factors were considered when looking over all the alternatives:

1. Overall performance.
2. Human and Ecological Risk.
3. Constructability.
4. Cost.

Mr. Smith explained the alternatives and the key considerations of each. He stated that there were five active alternatives and two "inactive" alternatives, one of which includes monitoring. (Please see the attached Ashumet Valley Plume Response Alternatives fact sheet dated July 1997.) Mr. Smith stated that the key differences among all the alternatives were the locations of the fences. Mr. Smith stated that data on the elevation of the water table and the plume, and groundwater models, led to the development of the alternatives. He displayed a summary table depicting the extraction rate per day, for each of the alternatives. Mr. Smith stated that the plume had moved into the silt. He stated that when the contaminants move into the silt, they are difficult to remove. Mr. Smith also stated that when the contaminants get into the silts, they are essentially immobilized. He stated that their strategy was to get at what moves, which explains why they do not achieve 100 percent capture.

Mr. Smith stated that in each of the alternatives, many of the fences were constructed along available access corridors for construction. He stated that the trade-off was that there were portions of the plume, the mass that was in the five PPB contour, that escape. Mr. Smith stated that they felt that the reason to allow a certain amount to escape, was appropriate because, the trade-offs were important, and the levels of concentration in those areas were fairly low. Mr. Smith stated that low conductivity silt, describes a low ability to transmit water.

Mr. Smith displayed a slide that depicted mass removal versus operating time. Mr. Smith stated that the data showed that the alternatives plateau around a twenty year time frame.

Mr. Smith displayed the graphic showing the risk associated with each alternative. He pointed out that the risk criteria was violated with phosphorous. He stated that that was the ecological risk target, which essentially was located in the phosphorous plume in the north end toward Ashumet Pond. Mr. Smith stated that through their modeling, and from what they know about the plume, they expect a concentration to impact the pond. He stated that they calculate 39 PPB and the EPA has a guideline of 25 PPB.

Mr. Smith stated that they would use right of ways, in regard to constructability, to the maximum extent possible. He stated that they will require between 80 and 115 properties to access the well fields. Mr. Smith stated that a treatment plant would be required, located in an area from which they would achieve the least distance of piping. He stated that there would be some additional properties that would be necessary for access.

Mr. Smith displayed slides of some of the construction associated with FS-12. The slides included pictures of the underground vaults and the finished product, being just a man-hole cover.

Agenda Item #4: Questions and Answers:

A member of the audience asked if in an exceptionally rainy season, would a dilution factor be included in the figuring of the flow. Mr. Smith stated that they were incorporating precipitation in modeling that they were doing. He stated that they account for the average precipitation as they project the mass that they can remove. Mr. Smith stated that the rain does tend to push the contaminants to depth and that is why they see them over most of the length of the plume at depth.

Mr. Smith stated that there was probably some dilution taking place, in that the plume had to grow to its present configuration. He stated that there was a mass of higher concentration, and as it moved it was impacted by infiltrated water. Mr. Smith stated that they assume the contaminants are moving with the water as if they were water molecules. He stated that they make that assumption to get a feel as to what the maximum extent would be.

Mr. Sobel asked, if there were a series of exceptionally wet years, or there was a long drought, would that affect the effectiveness of the systems. Mr. Smith replied that he did not think so. Mr. Smith stated that the only way that would have a considerable effect would be if the water table was dramatically drawn down. He stated that the systems would be designed to take into account the fluctuating water table.

Ms. Dupee asked how fast the Ashumet Valley plume was moving, and how far it was now. Mr. Snyder stated that the map of the plume is based on current knowledge from frequent sampling. He stated that the plume moves at a rate of one to two feet per day.

A member of the audience asked what role the septic systems play in the plume. Mr. Snyder pointed out the depth of the plume and stated that septic systems are usually just below the soil surfaces and above the water table, so the septic systems should not play a role.

Ms. Wojnar asked, what their treatment plan would be, when the plume hits a body of water. Mr. Snyder stated that with Ashumet Valley, the model predicts that the some of the plume will discharge at the Backus River. He stated that they are trying to eliminate that from happening. Mr. Snyder stated that phosphorus was a concern with Ashumet Pond.

Ms. Wojnar stated that she did not understand what they would do when that body of water becomes polluted. Mr. Snyder stated that once the surface water bodies are polluted there is not much that can be done. He stated that computer simulations do project some levels of volatiles.

Mr. Smith stated that all the alternatives do have extraction fence #1. He stated that they have found at the height of the Sagamore lens, the water table is sloping. Mr. Smith stated that there was pressure from the upper area pushing the water towards the sea. He stated that the water does not just flow laterally, over most of the length of the plume its primary direction of flow is vertical. He stated that where the fresh water is discharging into the salt water interface there would be strong vertical gradient. Mr. Smith stated that near the pond they tend to have more vertical flow in one end and downward vertical flow in the other end. He stated that they included a fence to ensure that they can control what the models were indicating, which was one percent of the volume of the plume likely going to the pond. Mr. Smith stated that the concentration of the one percent was not great, however they installed a fence to ensure that the phosphorous portion of the plume does not migrate into the water body.

Mr. Sobel reiterated that the purpose of extraction fence one was to keep contaminants from getting into the pond. Mr. Smith concurred. Mr. Sobel asked if the one percent would somehow get in, not withstanding the fence. Mr. Smith again concurred. Mr. Smith added that the modeling indicated that it was not likely to be an issue, however to be protective they have included fence one. A member of the audience asked if in fact one percent of the plume did get by the fence. Mr. Smith stated that that was correct.

Mr. Hearst stated that in the past the Air National Guard (ANG) did not choose to treat the source points, and he stated that that decision had been changed for all the plumes. He stated that the source point of the plume was located on the MMR and there was no treatment on government property. Mr. Hearst stated that assuming the highest concentrations are still on government property, why didn’t any of the solutions include treating the source against rainwater that will continue to push contaminants down in the plume. Mr. Snyder stated that the source is being ruled out as being a contributor. He stated that they have already started to see some degradation from the fire training area source. Mr. Snyder stated the fire training area will no longer be contributing contaminants to the plume. He stated that they were in the process of finishing the soils treatment there.

Mr. Hearst asked about treatment of the sewage treatment beds. Mr. Snyder stated that the sewage treatment plant was closed. Mr. Hearst stated that he understood that, however, the beds were still there. Mr. Snyder stated that they are no longer contributing. Mr. Hearst stated again that the sewage treatment beds were there, and they have not been remediated. Mr. Snyder stated that that was correct. Mr. Marchessault stated that there was currently a feasibility study being conducted, which was intended to look at different alternatives for evaluating those sewage beds. He stated that no remediation had taken place as of yet, and that it was still in the studying phase. Mr. Marchessault stated that if something occurred in the next year or so a decision would be made regarding any remediation of those sewage beds. Mr. Hearst stated that that was not included in any of the alternatives there that night. Mr. Marchessault stated that the alternatives addressed the groundwater contamination portions. Mr. Marchessault stated that a separate report would be done to assess the source area from the sewage bed. He stated that it would be done under a separate act. Mr. Snyder stated that the alternatives had to do with groundwater treatment. He stated that the sources were being dealt with in a separate program.

Mr. Sobel summarized that regarding the fire training area, they were in the latter stage of remediating the source. He stated that regarding the sewage treatment plant they were still studying it but they predict that a decision for action on that would be made within a year. Mr. Marchessault concurred.

A member of the audience asked if there was still ongoing contamination from the sewage treatment bed. Mr. Smith stated that the treatment plant had been closed, and that the flow had dramatically reduced. Mr. Smith stated that the source is limited at that point.

A member of the audience asked if the funding had been secured to carry the project through to completion, and if so what the source of the funding would be. Mr. Snyder stated that part of the Air Forces annual budget is devoted to the clean-up of the plume. Mr. Snyder stated that a commitment for the restoration was there, it was an annual funding process. The audience member asked if there was an approval process annually that could put the funding at stake. Mr. Snyder stated that a budget was submitted annually. He stated that the Air Force has to develop a budget for restorations. Mr. Snyder stated that the only instance he would think could affect funding would be if the military had to divert funds for a military action. Mr. Snyder stated that it could augment fund flow within a year, but it would always be repaid once the bill was restored from that activity. Mr. Snyder stated that that rarely happens, and rarely does the government shut down and not start the fiscal year on time.

A member of the audience stated that according to the calendar, a decision would be reached on September 2, 1997. He stated that he still had not heard what the preferred alternative was from the experts. He also stated his concern that the decision would be driven by dollars and not by probability of success. The audience member asked how the decision would be made. Mr. Sobel stated that the three members of the panel, Mr. Marchessault, Mr. Snyder, and Mr. Pinaud, were the decision makers. The panel concurred. Mr. Sobel then asked if they had a preferred decision, and if a decision had already been made. Mr. Snyder stated that they were in the process of making a decision. He stated that they wanted to hear the publics input on the alternatives. Mr. Snyder stated that a number of factors are considered when making the decision, ecological risks, effects to river flow, and effects to neighborhoods, to name a few.

Mr. Hearst stated that there seemed to be the best solution at one end of the spectrum, and then there was the other end, which was to do nothing, and it wouldn’t cost anyone anything. He stated that there had to be an alternative that was practical and affordable. Mr. Hearst expressed his concern as to how the panel was going to reach that decision. Mr. Snyder stated that a big part of the decision process was allowing the public comments to come in. He also stated that they have received more than 200 comments from the public, and different organizations, on the CS-10 plume, to date. Mr. Snyder expressed the importance of the public comments because the construction and the plume itself is in the community.

Mr. Sobel stated the RPMs have seen summaries of the written comments that came in during this process. He stated that the comments are reviewed and considered. Mr. Sobel also stated that there were citizen advisory teams to help facilitate public comment. Mr. Karson stated that the public comment period closes on September 2, 1997, and at that point the RPMs will continue to discuss and consider all the comments. He stated that the decision would be announced on September 15, 1997.

Dr. Price stated that he had looked at all the alternatives and concluded that "I" and "J" seemed to take the mass out quicker. He asked why they shouldn’t choose one of those alternatives. Mr. Smith displayed a slide to represent the amount of mass removed in ten to twenty years. He stated that the difference would be in the pumping rate, in regard to I and J. Mr. Smith stated that the potential for impact to the sensitive environment was something that they were trying to account for in their modeling efforts. He stated that they were doing an ecological survey over the next several years to develop a base line that would answer the questions, what were the biota, how sensitive were they, and how might they be impacted by the pumping strategies. He stated that with the alternatives, they were finding that as they increased the pumping rates they were likely to impact. Mr. Smith stated that they want to achieve appropriate capture while minimizing impacts to the environment.

Mr. Forden from Jacobs Engineering stated that in regard to alternatives "I" and "J", they considered the construction impact that would be imposed upon a large neighborhood. Mr. Smith concurred and stated that there was a good deal of construction impact with those alternatives. Mr. Snyder stated that constructability and ease of construction of the project may be a deciding factor when choosing an alternative.

Dr. Price stated that he had had twenty years of exposure and was concerned about getting sick. He stated that he wanted to get rid of the mass faster. Mr. Snyder stated that all the alternatives approached a plateau at about the twenty year mark. Mr. Smith displayed the Decision Criteria Matrix to give the public a sense of the life cycle cost for the systems.

Mr. Dow stated that he had read studies that the USGS had done, that pointed out that, if the phosphorous plume that was currently absorbed in the sediment, moved into Ashumet Pond it would increase the phosphorous more than three to six times. He continued that since Ashumet Pond was currently on the border of being moderately nutrient rich, it would probably move over to the category of being highly nutrient rich. Mr. Dow stated that in that case there would be a more extensive blue green algae bloom in the surface water which could cause taste and odor problems. He stated that there would be more growth of microscopic algae that would make the water devoid of dissolved oxygen which is required by fish and invertebrates. Mr. Dow stated that it was also quite common in highly nutrient rich systems that there was more growth of rooted aquatic plants in the shallow water. Mr. Dow stated that if the phosphorous was not dealt with there would be severe water quality impacts. Mr. Marchessault stated that they were taking Mr. Dows’ comments into consideration. He also pointed out that all the alternatives include some treatment of the Ashumet Pond area for phosphorous.

Ms. Rose expressed concern about the upwelling. She referred to Mr. Snyders’ statement that the contaminants prefer air to water and stated that at some point, if they were putting a hole into the ground, "things" could come up through air. Ms. Rose asked that the RPM’s explain the technology, who else had used it, and how successful had it been. Mr. Snyder explained the installation process of the extraction wells and recirculating wells. He stated that all the pipes used in the extraction wells were sealed. Mr. Snyder stated that the pipes are sealed to the wells, and he stated that there was not a point in the system where groundwater was opened to the surface air. Mr. Snyder stated that in regard to the recirculating technology, the air was controlled under a vacuum, it was not released into the environment and it was maintained in a sealed system.

Ms. Rose stated that according to Mr. Snyders’ statement she understood that, as the plume meets water it rises towards the surface. She stated that she lived near the Backus River Road, and expressed concern about the natural occurrence in twenty years when the plume meets water. She asked if there was presently any upwelling that was creating breathable problems. Mr. Snyder stated that they were collecting surface water sampling on the Backus River. He also stated that the Backus River flows from groundwater. Mr. Snyder stated that the model predicts that some plume may go to the river.

Mr. Sobel asked Mr. Snyder to answer the question in regard to the amount of experience there had been with the two technologies. Mr. Snyder stated that pump and treat systems were fairly reliable, and that they were the standard for dealing with groundwater contamination. Mr. Snyder stated that the recirculating wells are still considered innovative. He stated that they had done a pilot test of six wells in three different settings on the MMR last year and the results had shown that it does have promise for water balance and getting the contaminants out. Mr. Snyder stated that the recirculating wells have had much more use in Europe than it has in the States to date. He stated that from their pilot tests and from the history of the recircs., it does have some application.

Ms. Eadie stated that her concern was the noise level. She also expressed concern about the treatment plants. Mr. Smith stated that for the cost analysis and the decision criteria matrix, they made an assumption that the treatment plants were in the areas shown. Mr. Smith stated that treatment on the base is an option. He stated that it would be very expensive to pipe to that location. He stated that he would like to receive comments on that subject. Mr. Smith stated in regard to the noise issue, that the recirculating well at the CS-10 plume near the MMR, was designed as pilot test to test the technologies function below ground. Mr. Smith stated that they felt they could take care of the noise issue, one option being to build a permanent structure to suppress the noise. He stated that the extraction pumps for the ETR system do not tend to be very noisy because the pumps are well below the water table at the depth of the plume, and the noise is dampened by the water itself. Mr. Smith stated that the treatment plant would be the only real source of noise. He stated that the way the pilot test was configured, they have one treatment shed per pair of wells. Mr. Smith stated that when they go to detailed design they would take into account these concerns and perhaps bring a series of ten wells into one treatment shed. He stated that what makes the recirculating well option attractive, is that there is a decentralized smaller building, however as Ms. Eadie stated, the building may not be aesthetically appropriate for that area. Mr. Snyder stated that they want sub surface vaults on all the roadways. Ms. Eadie asked if the community would be able to voice their opinion on the this issue.

Mr. Snyder stated that throughout the process, after a decision is made the execution plan lays out the selected alternative, what the construction will be like, and how it is going to perform. He stated they have meetings throughout the whole process to discuss the design.

Mr. Sobel suggested that Ms. Eadie submit her concerns as written comments. Ms. Eadie concurred.

A member of the audience asked if they would have any choice about where the wells would be placed, once a decision is made. He then expressed his concern of having a well in his front yard. Mr. Snyder stated that they will need to have property access for each of the alternatives. He stated that they would either go the property owner and request an easement or a lease for the right of way, and yes the property owner will have the right to deny access Mr. Snyder stated that in that case, plans would have to be altered to work around that design. Mr. Sobel asked what would happen if they had an option that involved putting a well in the audience members yard. Mr. Snyder stated that the real estate specialist deals with acquiring access to private property. He then stated that they would arrange a lease or payment for an easement on the property. The audience member asked what would happen if he refused access to his property. Mr. Snyder stated that they would have to work their design around that impediment and see if they could locate that well somewhere else.

A member of the audience asked how much destruction there would be once construction was started. Mr. Snyder stated that there would be anywhere from twelve to twenty four months of construction. He clarified that it would not be twelve to twenty four months of construction at any one spot. Mr. Snyder stated that individual spots would have from two weeks to three months of construction to get the wells in place. He stated that once the roads were restored, all that would be seen would be a manhole cover. The audience member asked if in fact it could cover several months. Mr. Snyder concurred. The audience member asked when construction would start. Mr. Snyder stated that the scheduled startup date is before 1999, however construction would begin right away.

Mr. Clark asked how many properties would be involved in regard to the construction phase. Mr. Snyder stated that approximately 80-115 properties would be affected. Mr. Smith stated that for the entire set of alternatives, between 80 and 120 private parcels would be impacted by the well fields themselves. He also stated that additional access would be required for the piping itself, however that part of the concept has not been worked out in detail, but they would be using right of ways to the extent possible to minimize use of private property. The audience member asked if they had an estimate in regard to the amount of acreage that would be impacted with any one of the alternatives. Mr. Smith stated that there would be a twenty five to thirty foot radius for each well. Mr. Sobel asked approximately how many wells there would be. Mr. Smith stated that he could not answer that question, he could however get the information for the audience member.

The audience member stated that the diagrams of the alternatives imply that they would be setting some roadways to get at the pumping stations and wells. Mr. Smith, using alternative "I" as an example, stated that it would require a good deal of cutting of temporary roadways to get in. The audience member expressed concern because the construction would be on his favorite golf course. Mr. Smith displayed the aerial photo to show the area of concern. He stated that the audience member was correct.

Mr. Hulfrieh stated that there had been no mention of certainty of their calculations. He stated that the percentage of efficiency differs by two percent and he found it hard to believe that they could make a calculation that accurately. Mr. Hulfrieh stated that they did not give any indication that they know that this will actually work. He stated that they were being close to dishonest by not discussing the uncertainties. Mr. Hulfrieh stated that the only alternatives that exceeded the criteria for hazards, were the two "do nothing" alternatives. He asked how do they make that calculation. Mr. Sobel clarified the two points Mr. Hulfrieh made as, precision in the numbers being presented, 93% capture versus 91% capture, and what their confidence levels was in those numbers. He stated that they could model and estimate the performance of the alternatives, but the real proof comes in the actual performance. Mr. Snyder stated that they will monitor the performance of whichever alternative is selected. Mr. Snyder stated that there was a lot of uncertainty. He stated that a lot of the uncertainty was dealt with throughout the construction time period. Mr. Snyder stated that assumptions were made throughout the risk assessment. He stated that typically when they do not know the exact number and they have to make an assumption, they assume the worst case, the most conservative approach.

Mr. Hulfrieh stated that all the alternatives were indistinguishable, and stated that the "do nothing" alternative was safe, with the exception of some issues about ecological hazards, primarily phosphorous. Mr. Hulfrieh stated that he found it difficult to understand how they were making decisions in distinguishing amongst the alternatives when, when they introduce the uncertainty there was virtually nothing to distinguish the alternatives. Mr. Snyder concurred that it was difficult. He stated that there was not an obvious favorite of any one alternative. Mr. Snyder stated that public acceptability may be the determining factor. He stated that there were many factors that come in to play when making this decision.

Mr. Zylirion asked what the institutional controls were in regard to putting wells in certain places, and how they were evaluated. Mr. Snyder stated that the two primary institutional controls that would determine future exposure to that groundwater would be, a preclusion from groundwater use, and a provision of public water through the reservoir. He stated that one would be health board moratoriums on private well installations and the other would be providing public water, which would be part of the cost to the Air Force. Mr. Sobel asked how the institutional controls affect the decision making process. Mr. Snyder stated that these controls were assessed in the decision criteria. He stated that they assess how well the controls could be regulated and enforced. He stated that the Air Force Center for Environmental Excellence (AFCEE) had looked at that issue, and it was part of the balance.

A member of the audience asked what percentage of the mass of contaminants was in the toe area of the plume that was south of Carriage Shop Road. Mr. Smith stated that it was in the neighborhood of three percent. The audience member then asked why AFCEE was expending so much effort to capture three percent of the plume. Mr. Smith stated that a lot of the goal has been 100% capture. He stated that they were dealing with a small percent in that area. Mr. Smith stated that the ecological sensitivity was something that they were balancing. He stated that with the more aggressive approaches they did have some problems with the design criteria, in regard to the flux of treated water that moves toward the pond. Mr. Smith stated that it was a good point and that it deserved a written comment.

The audience member stated that the models themselves were the best that human beings could do at this time. He wanted to clarify that when AFCEE talks about 100% containment, they were referring to 100% containment of anything above 5 PPB. He stated that everything from zero to 4.99 MPL is allowed to be lost. He suggested that AFCEE back up a bit and simplify the time, the cost, and the socioeconomic impact.

Mr. Marchessault stated that Mr. Smith indicated a three percent mass below Carriage Shop Road and clarified that the purpose of some of the fences along Carriage Shop Road was to let all the contaminants come through the fence and get treated. He stated that some of the alternatives which do not address the area below Carriage Shop Road, would not let that roughly three percent get by. Mr. Smith added that one of the alternatives did not include much action in the southern end.

Mr. Ryther stated that there was three and a half parts per billion (ppb) of TCE in his well water and he asked why TCE was following the same lobe of the plume that sewage follows. He asked if it this implied that all the TCE in the base goes into the sewage treatment. Mr. Smith stated that no that was not true. Mr. Snyder stated that not all the TCE on the base was part of the Ashumet Valley plume. He stated that most of the plumes on the base contain TCE. Mr. Snyder stated that the detections Mr. Ryther was mentioning were to the west of the location being discussed. He stated that the TCE was not related to the area in which Mr. Ryther lives, and that it comes from two different parts of the base. Mr. Ryther asked where the TCE came from and how many different sources were there on the base. Mr. Snyder stated that TCE was a widely used solvent across the base. He stated that other plumes, Ashumet Valley, Land Fill 1(LF-1), and CS-10 for example, all have TCE in them, but they come from different sources on the base. Mr. Snyder stated that the TCE they found in the Crane Wildlife, was part of the area they were working on the definition of in the upcoming year. He stated that finding TCE there was something new and that was why AFCEE had been providing that neighborhood with bottled water.

Mr. Gill stated that as treated water was put back into the area from which it was extracted, fresh water would mix with contaminated flow and they would have to treat water that had already been treated. He stated that over time there would be a decrease in the level of contaminants caused by their own influence. Mr. Gill asked if there were measures to counteract that false data and possible false capture. Mr. Snyder stated that they were trying to keep reinjection as close to extraction to maintain overall hydrological value. He stated that they did not want to recirculate too much in water, to avoid treating water that had already been cleaned. Mr. Snyder stated that they were trying to minimize possible recirculation of clean water into their extraction. Mr. Smith added that part of their performance monitoring system would be wells outside of the influence downflow pass from the extraction fences. He stated that that would be looking at groundwater contaminant levels there and they should clean up as clean water is reinjected at that fence location.

Mr. Gill asked if that meant that there would be well sites to be implemented that were not represented on the charts. Mr. Smith stated that if they go to final design on a system, they will then prepare a performance monitoring plan which would involve a series of monitoring wells to determine what the concentrations were that were going into the fence. Mr. Sobel stated that samples would be taken at other locations that might be similar in characteristic, to identify a reference pond with which results would be compared. Mr. Smith concurred with Mr. Sobels’ statement.

Mr. Burwell stated that he lived on Green Pond down stream of the Backus River where fresh water meets salt water. He asked if that would pose a problem. Mr. Burwell asked Mr. Snyder if he had investigated the use of extraction wells and reinjection wells. He also asked if they had investigated the use of clean groundwater coming from a treatment plant. Mr. Snyder stated that there would be an answer in the responsiveness summary due to go out at the beginning of the next week.

Mr. Callahan asked what the comparison of the effect of the different approaches was on Flax Pond. Mr. Smith displayed the cross section of the plume and stated that the plume was at depth at a fair distance below the water table. He stated that the actual groundwater table was just over twelve feet above sea level. Mr. Smith stated that the contaminants were generally at depth. He stated in regard to impact to Flax Pond that it was part of their design criteria established for the modeling, to be cognizant of the fact that they are reinjecting treated water. He stated that the reason extraction reinjection was fairly close in space was that they are trying to balance the hydraulics to minimize the impact to the water table. Mr. Snyder stated that they want to minimize recirculation of clean water, while balancing the hydraulics.

He stated that one of their design criteria was, that the amount of water that goes into the aquifer did not exceed the flux. Mr. Snyder stated that it was not likely to have an effect on the pond. He stated that to be safe they made an assumption that they do not want to exceed a 25% flux of treated water to the pond. He stated that in terms of the plume they do not expect it to be surfacing in the pond, but generally flow is horizontal and eventually it surfaces toward the ocean. Mr. Smith stated that there was some portion of it, in any point of the plume, that has to potential to come up. He stated that actual impact of contaminated water to the pond, from what the modeling and data were showing, there was no indication that there was discharge there.

Mr. Sobel asked Mr. Smith to explain the statement "not to exceed 25% flux". Mr. Smith stated that the ponds were a representation of the aquifer. He stated that it was essential for water to move through ponds to prevent stagnation. He stated that the flux was the change over, the water moving through the pond. Mr. Smith stated that in the deeper zones, it was more likely that those zones could feed to the pond. He stated that generally the water was feeding in the northern end and discharging in the southern end.

Mr. Sobel asked if Mr. Smith was able to prepare the impact to Flax Pond of the various alternatives. Mr. Smith stated that the decision criteria matrix showed the hydrological thresholds. He stated that it would show exactly what the flux number was.

A member of the audience stated that the projection for alternative B1 had changed from the literature that was available in July versus what was available now. He stated that in July B1 talked about being at or below the hydrological zone and B1 now talks about being above that zone. He asked if there had been a typo or if in fact there was a change. Mr. Smith stated that he was not sure. Mr. Marchessault stated that in the decision criteria on page five, there was a discussion of the different alternatives, and it showed that B1 was below all the criteria. A member of the Jacobs Engineering technical staff stated that the numbers that were in the present copy of the decision criteria matrix were correct. He stated they had in fact changed. He stated that the recirculating wells were revisited and that alternative now passes the threshold.

Mr. Nowlan asked how fast the plumes were moving and how far they would go per week, per month, or per year. Mr. Smith stated that the plumes at MMR move at a range of one to three feet per day.

Mr. Winters asked what effect alternative B1 would have on the cranberry bogs along the Backus River. Mr. Smith stated that they presently have the ecological monitoring program, which supports all of their design work, and looks at the potential surface sites where the plume could be moving. He stated that they were currently getting data on that. Mr. Smith stated that they would be reporting back fairly soon, in regard to the surface water sampling data and testing data.

A member of the audience asked if they would get the information back in time to influence which alternative they would select. Mr. Smith stated that the modeling was showing that the plume for the most part is deep, and the discharge they expect to see, the greatest volume of that plume, was further south. He stated that there was some discharge in the area of groundwater, because that was where the surface water flow was coming from, in the Backus River. Mr. Smith stated that there was a zone of clean water above the plume that was likely to be feeding that area with some percentage of water at depth. The audience member stated that his concern was beyond Old Meeting House Road and Old Barnstable Road further south of Flax Pond and asked if the plume would eventually come out in that area. Mr. Smith stated that the data they had to date did not indicate that they were getting discharge of contaminants in that location, he stated that it was probably not likely. Mr. Smith stated that with the alternatives, they were proposing to stop the migration or cut it off. The audience member referred to alternative C1 and stated that he was concerned because the toe of the plume was not being addressed.

Mr. Sloate stated that beyond the surface flow the contamination was about foot level to the surface flow to the bogs. He stated that if they look at Pond 14, which is north west of Flax Pond, there was a connection between Pond 14 and Flax Pond. Mr. Sloate stated that this was a town easement, and there was substantial flow in the winter, and in periods of high rains. He stated that there may be a possibility of contamination being pulled to the surface by the river because it looks like the plume at the 70 foot level was somewhat diminished in the areas where there was substantial surface flow. He stated that that indicated that the contamination was going somewhere, and he asked if there was any possibility of cutting off the flow from Pond 14 and the Coonamessett flow area so that there was no migration of contaminants to the surface water itself. Mr. Goydas from Jacobs Engineering, stated that there was an upwelling in the Coonamessett. He stated that they do not see much upwelling to some of the smaller surface water bodies such as Pond 14 and Flax Pond, although they do evaluate them. He stated that the alternatives that include downgrading toe containment, are looking at preventing groundwater flow going to Pond 14, Flax Pond, the Coonamessett River and the Backus River. He stated that alternative G allows natural attenuation, there was a lot of discharge over the long term to Coonamessett and the Backus River.

Mr. Walsh asked if the recirculation technology was proven to treat inorganics. He stated that looking at the history of the whole evolution of the plumes on the Cape, it seems as though more were being discovered every day. He stated that with construction of any one of the alternatives, they would find some "surprises". Mr. Walsh stated that they should take a more distributed approach toward a central processing plant. He felt that they would find things out that violate the assumptions of the models, and will mandate "on the fly" fixings. Mr. Walsh stated that the MGD Building shown in the slide, was pretty obtrusive. Mr. Walsh stated that they should take consideration to distributing this treatment around the toes and up in back where it might be less obtrusive to the residents and to the ecology. Mr. Snyder stated that they were looking for appropriate places for treatment facilities. He stated that they would not put an industrial building on a residential street. Mr. Snyder stated that they would put treatment facilities in opportune locations that were out of sight. Mr. Snyder stated that recirculating wells would not treat inorganics without some additional treatment. He stated that they would have to take the water above ground into the carbon treatment process, to treat for inorganics. Mr. Walsh asked if the ETR sites may change. Mr. Snyder stated that they may change. He stated that there were several locations where they scheduled recirculating wells, and they would change based on the approach they take. Mr. Snyder stated that the standard approach they show in the diagram referred to the pilot test.

Mr. Deasy stated that with a number of the proposals the process was very centrally located. He stated that the alternatives with more spread out processes were considerably more expensive. Mr. Deasy asked if they would revise the estimates if less obtrusive means were considered. He asked how they were reconciling the 33% cost difference with some of the proposals. Mr. Snyder stated that their off base construction assumes that they would have to do fairly aesthetic work. He stated that they would do as much vaulted work as possible. Mr. Snyder stated that the intent was that the construction may be an impact, however, when they leave the construction site they will assure that the site would be restored, roadways would be repaired and landscape would be replaced. Mr. Snyder stated that they typically leave the area in better condition than it was prior to construction. Mr. Deasy commented that some of the neighborhood during the entire construction process were much more highly affected than with different plans.

Ms. Delisle stated that the area in which she lived was not polluted, however she did not believe it when AFCEE told her that contaminants were not traveling her way. Ms. Deslisle stated that spots down below Round Pond, were polluted. She stated that she received a letter from Mr. Snyder which she found confusing. Ms. Delisle stated that the letter said that AFCEE would come test her well semi-annually, however they presently come Bi-weekly. Ms. Delisle asked if the letter was referring to a different kind of testing than what they were already doing. She did thank AFCEE for delivering water to her house. Mr. Snyder stated that they would be the same analytical tests, however based on their investigation of FS-28 they were defining where the plume is at and where it is not. Ms. Deslisle stated that in October, AFCEE was going to cease delivery of water to her. Mr. Snyder stated that AFCEE provides bottled water to areas in which they are doing the two week sampling. He stated that once they determine that the people in that area are not at risk, they will stop supplying water. Mr. Sobel encouraged Ms. Deslisle to follow up with Mr. Snyder following the meeting.

A member of the audience stated that the Cape had a history of electrical failure, and he asked what effect that would have. He also asked if anyone had considered to recycle the water in the ocean to provide the water supply. Mr. Snyder stated that use of the ocean water for water supply was not part of the program, they are dealing with the clean up of the aquifer. He also stated that certain treatment plants were known to increase electrical demand on the Upper Cape. Mr. Sobel asked if there was an analysis of the demand and supply, and if there may be trouble in the future in regard to meeting the demand needs. Mr. Snyder stated that there has been an analysis of the total system. He stated that they would have to revisit that issue, and they will be discussing the issue with Commonwealth Electric. Mr. Snyder stated that he anticipated a demand in the long run.

Ms. Voeker stated that it seemed as though AFCEE was devoting most of their energy to treating the organic contaminants, and the inorganic contaminants are being treated as more of an after thought. She stated that looking at the risk assessment, the one thing that shows up at above one on the scale was the phosphate. Ms. Voeker stated that she would like to understand that. She then asked if well water was considered in the risk assessment. Mr. Snyder stated that well water for ingestion as a primary exposure route was not used for risk assessment because of their ongoing efforts to put anyone at potential risk, on public water. He stated that therefore the exposure pathway was cut off. Ms. Voeker asked if the assumption was, to keep monitoring, and whenever somebody’s well was above what was acceptable, they put them on public water. Mr. Snyder stated it does not necessarily have to be in the well, but when the plume gets underneath the piece of property. He stated that if the plume migrated to a certain location, they have a buffer zone and based on current knowledge, they would start discussion with the water districts of the towns to put those people on public water. Ms. Voeker stated that with the no monitoring option they would not know. Mr. Snyder stated that that was true with the no monitoring option. He stated that even with natural attenuation, instances of control were part of that and they would continue to put people on public water wherever the plume would migrate to.

Ms. Voeker asked if there were other human exposure pathways that AFCEE felt were too insignificant to list. Mr. Snyder stated that AFCEE and the regulatory agencies met with people, whose specialty was forming risk assessments, and looked at the scenarios, and what the potential exposures were in a wide range of instances. He stated that the driving exposures and human receivers were swimming and cranberry growers who were most likely to have high exposure.

Mr. Sobel asked Mr. Snyder if there was more information about the risk assessment available for anyone who was interested. Mr. Snyder stated that the information was available in the matrix.

Mr. Snyder responded to Ms. Voeker’s statement that inorganics were being treated as an afterthought, stating that she was very observant. He stated that it was a bureaucratic problem in the eligibility of contaminants under certain programs. Mr. Snyder stated that dissolved organics, based on how they were released, were covered under certain environmental regulations and funding from department of the Fed’s. He stated that they have looked at them both and in this situation, and inorganics were a significant part of the concern for Ashumet Valley. Mr. Snyder stated that they have included that in their assessment even though it had to be funded through different channels.

Mr. Sobel reminded the audience about the response alternatives form and the presentation evaluation form. He stated the importance of the forms in regard to making the public meetings as effective and efficient as possible. Mr. Sobel thanked everyone for coming and closed the meeting at 9:10 P.M.