State teams describe PCE/TCE contamination near former Central Avenue landfill; homes fitted with filters and ventilation systems

State remediation staff and Maine CDC briefed Limerick residents on June 30 about investigations and short‑term protections after chlorinated solvents were detected near the former Central Avenue landfill.

Aaron Dumont, a remediation specialist with the state’s remediation bureau, said the team used historical records and targeted sampling to refine a search area around the closed landfill and collected 10 groundwater samples from residential wells. "The department collected a total of 10 groundwater samples from residential wells around the former Central A landfill," he told the meeting, and the team found some samples above remedial action guidelines that prompted immediate steps to reduce exposure.

Brendan, the project geologist, described how dense chlorinated solvents such as tetrachloroethylene (PCE) and trichloroethylene (TCE) can sink in sand-and‑gravel aquifers and enter fractured bedrock, noting the two primary exposure pathways relevant to nearby homes are vapor intrusion and contaminated drinking water. He said soil sampling in garden and yard areas recorded occasional low detections that were “well below the residential RAGs” for soil.

Don White, an environmental engineer on the team, explained how vapor intrusion can draw contaminants into basements and described the mitigation installed at three houses. "We installed three SSDS systems ... and we took new samples and all three ... passed with a reduction of 97% of the contaminants, 88% reduction and 92% reduction," he said. The SSDS systems are being installed and tested to radon‑system standards; in houses where indoor air was at or near RAGs, the team sealed floor‑wall seams and will retest, especially during winter when the stack effect increases vapor draw.

The department also installed whole‑house carbon filtration on three households (225, 235 and 236 Central Avenue) and is sampling the filtration systems quarterly through 2026 to evaluate long‑term effectiveness. Dumont said monitoring will inform whether sampling frequency or system design can be stepped back after one year of consistent results.

Maine CDC’s assistant state toxicologist, Tom Simmons, answered health questions from residents. He said, as a general matter, studies show PCE and TCE show little uptake into the edible portions of most garden vegetables, and advised rinsing produce. On health effects he said both chemicals have non‑cancer and cancer associations: "for PCE, we're concerned about ... if a pregnant individual is at home and drinking the water ... there's a risk of ... heart defects," and for higher long‑term exposures worker studies have shown possible neurological effects; cancer risk guidance under the RAGs is framed as a one‑in‑100,000 excess‑risk threshold.

Residents asked about the extent of the plume and whether additional bedrock monitoring toward Lake Arrowhead is planned. The remediation team said much of the chlorinated solvent mass has migrated into deeper fractured bedrock in some areas, which makes locating all sources hard without extensive bedrock drilling. The team said bedrock programs are expensive and require resources; they plan to use targeted soil borings, monitoring wells and geophysics to improve source‑zone delineation before committing to larger drilling programs.

Several residents raised questions about potential responsible parties for historic dumping. The department said tracing generators decades after disposal can be difficult and that the agency is compiling historical records and local interviews to seek leads. Nick Hodkins, director of the state Division of Remediation, said the priority for now is protecting affected residents’ drinking water and indoor air; while some federal programs can help, the site does not look like a straightforward Brownfields redevelopment candidate and Brownfields funding is therefore unlikely to cover the full costs of a large cleanup.

Next steps the team listed include continued quarterly sampling of installed filtration systems through 2026, winter retesting of indoor air to confirm SSDS performance during the heating season, optimization and sealing of homes with marginal results, and further source‑zone work (borings, wells, and geophysical surveys) to refine a long‑term remedy.

The public hearing closed after extended questioning; the select board then recessed and moved to its regular agenda.