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Ashland Conservation Commission presses developer on contamination controls, dewatering and soil testing at 10–60 Main Street
Summary
At its June 22 meeting the Conservation Commission pressed SLV Ashland LLC and its consultants on plans to manage contaminated soils, dewatering discharge and the proposed treatment train for the 40B redevelopment at 10–60 Main Street, and requested peer‑review of additional soil borings; the hearing was continued to July 20.
At a June 22 meeting the Ashland Conservation Commission extensively questioned the applicant team for the proposed 40B redevelopment at 10–60 Main Street about contamination controls, dewatering operations and how excavated soils will be tested, contained and disposed of.
The applicant team, represented by Lucas Environmental and contractors including Callahan Construction and McPhail Associates, said it will add 11 soil borings (four inside buildings, five outside, and two grab samples at the raceway inlet and outlet) and will test site soils before reuse or off‑site disposal. "Stone tracking pads are standard best management practice (BMP) for preventing sediment accumulation on the roadways during construction," Mr. Lucas said; site sweepers and a subcontractor will also remove tracked material, and the team said street sweepings that test positive for contamination will be stored and sent to an approved facility.
Why it matters: the property sits adjacent to the Sudbury River in an area that intersects the Nyanza groundwater plume mapped by the EPA, and commissioners pressed how temporary construction activities could release contamination to the river and downstream wetlands.
Dewatering and treatment: the team described a construction dewatering system that will pump collected water to an on‑site treatment train anchored by an FRAC tank (about 18,000 gallons) and modular filtration units (vapor‑phase carbon, bag filters, air stripper, liquid‑phase reactivated carbon and cartridge filtration). McPhail Associates said the EPA Dewatering and Remediation General Permit (DRGP) will govern initial and ongoing testing: two influent/effluent tests during the first week with 48‑hour turnaround, then monthly sampling thereafter. "Per the DRGP, discharge must be halted as soon as possible, but no later than 72 hours, if one or more of the tested parameters fails to meet the allowable discharge limits," the applicant team said.
Stormwater and StormTrap™: the permanent underground StormTrap™ detention system is designed with sealed precast seams, a solid concrete bottom and a rubber membrane; the applicant said the system is intended to be watertight and will be inspected under the site's Long‑Term Operations & Maintenance Plan twice per year. Commissioners asked whether the system or stormwater would be tested for groundwater contamination post‑construction; the team said a professional engineer will inspect installation to verify watertightness but that routine groundwater testing after construction is not currently planned.
Soil and concrete materials: the developer will run a Hazardous Materials (Haz/Mat) survey of existing buildings before demolition and abate identified hazardous building materials as required. The team said concrete slabs can be ground and a geomembrane vapor barrier installed in retained commercial buildings (10 Main Street) and that vapor mitigation (similar to radon systems) will be used where necessary; sub‑slab soil gas monitoring at 10 Main Street was reported to be below MassDEP commercial screening values, though commissioners noted some RAM report values exceed residential screening thresholds for compounds including TCE and PCE.
Excavation risks and tank design: commissioners flagged that the proposed stormwater/tank excavation is near the mapped Nyanza plume and asked how saturated excavated soils and groundwater infiltration will be managed and tested. The applicant said temporary excavation support, localized dewatering prior to bulk excavation, stockpiling with covers and decanting, and engineered pre‑cast concrete tanks (designed to resist uplift) would be used. The team acknowledged alternatives (shallower tanks) are under consideration to reduce infiltration risk.
Peer review and next steps: the commission said it will rely on independent peer reviewers for contamination, floodplain and stormwater (Partners Environmental for LSP/contamination, Beals & Thomas for floodplain, and GCG Associates for stormwater). Commissioners agreed the applicant may proceed with the additional borings but that peer reviewers will evaluate whether the proposed locations and depths are adequate. The applicant agreed to return to the Conservation Commission on Monday, July 20, 2026.
Public concerns and enforcement: multiple residents raised concerns about the site's location in the Nyanza plume, whether an amended Activity and Use Limitation (AUL) permitting residential use will be approved, and how enforcement and monitoring would occur during and after construction. Commissioners said some issues (AUL approval, DRGP compliance) fall under state or federal jurisdiction and noted the town will consider LSP oversight and whether a performance bond or other surety is required.
What remains open: peer reviewers must evaluate the RAM and Soil Management Plan and confirm whether the proposed borings, treatment train and dewatering approach are sufficient; the commission reserved further contamination questions until their LSP peer reviewer could be present.
The hearing was continued to July 20, 2026. The Commission voted later in the meeting to adjourn at 9:16 PM.
