The Martha’s Vineyard Airport Commission unanimously voted to move forward with the PlumeStop pilot project with Tetra Tech, the firm that has been handling testing and mitigation of per- and polyfluoroalkyl substances (PFAS) around the Martha’s Vineyard Airport area.
PFAS describes a family of long-lasting chemicals that break down very slowly, which is also why they are nicknamed “forever chemicals.” Extended periods of exposure to PFAS, or high concentrations of the chemicals, are toxic, and can affect developing fetuses, thyroid, liver, kidneys, hormone levels, and the immune system. The chemicals have also been known to create a cancer risk. Tetra Tech completed the first stage of PFAS investigations in 2019. PlumeStop, an activated carbon substance made by the company Regenesis, is the tool Tetra Tech vice president Ron Myrick proposed using to mitigate the spread of PFAS in area south of the wastewater treatment plant, which is near locations aqueous film forming foam (AFFF) testing or usage occurred in the past. According to Regenesis, the research and development for PlumeStop began in 2007, and was launched for commercial applications in 2015.
During Thursday’s Airport Commission meeting, Myrick said a new detail is that the area that received the “predominant testing of AFFF over the years” is still a “significant source” of PFAS, according to Tetra Tech tests done in the summer. “The idea of the pilot test was really to demonstrate the technology, and that’s what we originally were thinking we would do with a barrier closer to the pedestrian way, the bike path. We had the well infrastructure in place to do a good test to show us if this technology worked,” Myrick said. “We pivoted off that, and decided we now have much more information to show that testing of this, or doing a treatment, just … down-flow of the [significant source of PFAS] could have a significant benefit.”
Myrick said “one of the first tasks” will be to further refine the “lateral and vertical information” of the groundwater flow to “maximize the treatment.”
“Task two is reviewing that information, refining that with our contractor. Task three would be injecting the PlumeStop. 9,200 pounds is currently proposed, in a water-slurry mixture,” he said. “We included additional wells just down-gradient of that PlumeStop barrier, and monitoring that through June, quarterly events.”
While presenting the pilot’s scope, Myrick said, “The idea is to understand a fairly well-understood technology,” but also to “demonstrate that it works” at the airport for possible expansion of PlumeStop use for PFAS mitigation.
The pivot to “refining a design,” installing six new wells for the pilot, and adjusting the wells’ placement in a way for the PlumeStop to capture PFAS in a “shotgun” direction means the project will cost more, compared with the $185,000 Myrick presented in August.
Commissioner Geoff Wheeler asked since the PlumeStop is being done close to the PFAS source in a southerly direction, “does that give us, in theory, a better argument if we test at some point behind it and have really low numbers or no numbers, that some of it, other wells, downstream is not from us?” Myrick said areas further downstream from the airport have already been tested “decades ago, that [have] migrated in that direction,” adding that these tests are for wells with higher PFAS concentrations. Lower PFAS numbers could indicate another source, such as septic systems, but higher numbers could indicate AFFF.
“The barrier, the real intent is to mitigate to the extent possible what is going to migrate off the airport, and in time that will improve the situation south of the airport,” Myrick said.
Wheeler continued by saying he understands Myrick’s statement; he also wanted to know whether there was a way to decrease the annual spending on the PFAS mitigation program going forward, or if the price would increase.
“The base spending we expect to happen over the coming years is to monitor private wells, maintain treatment systems, and comply with the reporting requirements with MassDEP [Massachusetts Department of Environmental Protection]. That number is somewhere in the $200,000- to $250,000-a-year range. I don’t see that changing in the near future,” Myrick said. “The additional task [is] trying to decrease the time that you need to do that. Is it going to be a few years, is it going to be decades? It really depends on how effective the program is [at mitigating] what migrates off the property and into the down-gradient area.”
The current estimate is $272,500 for the entire project, Myrick later clarified during the meeting.
Commissioner Bob Zeltzer said he is in favor of the program, and the airport does not have “a lot of options,” but pointed out the uncertainty of the “effective life of the barrier, and when it will stop doing what we want it to do.”
“The answer to that is to build another barrier beyond it,” Zeltzer said. “We just have to be aware that’s a possibility.”
Myrick agreed that this was a fair statement, but said, “If you’re saturating your barrier and you need to put in another barrier, you just stopped a lot of PFAS from migrating off the property.”
“We don’t want to overdesign, and it’s easy enough to come behind this one and inject another layer,” Myrick said, adding that the lifespan of the PlumeStop barrer will depend on what is coming down into the barrier. “We’re learning more about that. We just don’t have the final answer.”
In answer to a question from commissioner Don Ogilvie, Myrick said Tetra Tech has worked with Regenesis for PlumeStop PFAS mitigation before, in Pennsylvania, for example.
Commission chair Bob Rosenbaum asked if the PlumeStop barrier could become a source of PFAS over time after it has absorbed what it could.
“It may or may not remain in perpetuity. If there is another compound that’s migrating through the aquifer that will attach onto the activated carbon as well, it might attach onto that spot and kick off the PFAS, in a nonscientific term. There is preferential absorption that could happen,” Myrick said. “But, we’re talking decades … there is a possibility that we can see a low-level concentration many decades from now coming off this barrier, because of the geochemistry or whatever else is flowing through the aquifer. I think that likelihood of being a real problem is low. I think it’s far enough in the future, and also it’s going to be a small amount that comes off. If we’re seeing that there’s an overload of the barrier, then that’s when there’ll be a recommendation to put a new barrier behind it.”
Myrick added that Martha’s Vineyard has a very clean aquifer, without many other contaminants in it, so he doesn’t “expect it to be a possibility,” unlike in an urban environment. Rosenbaum followed by asking whether there has been a “call to extract the PlumeStop,” to which Myrick answered, “Nope, it’s not really feasible.”
The commission authorized the airport to enter into a contract with Tetra Tech to inject the PlumeStop. Myrick said a schedule is “penciled in” to start drilling wells in a couple of months, but the next step is to submit a plan to MassDEP. “We want to get this in before the winter,” Myrick said.
The commission later entered into an executive session “to discuss [strategy] with respect to litigation regarding PFAS” with individuals relevant to the issue, including Myrick and the legal team from Boston-based law firm Anderson & Kreiger.