EPA approves early removal for Lower Neponset River reach; MassDEP notes $78.5M estimate

MassDEP staff told the advisory committee that EPA headquarters recently approved an early removal action for reach 1 of the Lower Neponset River to address PCB-contaminated sediments and floodplain soils.

Diane, representing federal programs at MassDEP, said the action covers roughly the first mile from the confluence of Mother Brook to the TNH Dam and targets sediments with PCBs greater than 1 milligram per kilogram in two critical deposition areas. The removal scope includes: excavation of sediments exceeding cleanup goals, removal of PCB-contaminated floodplain soils in the 100-year floodplain, installation of permanent caps where cleanup goals cannot be met and, if necessary to facilitate grading and remedial work, removal of the dilapidated dam near the Tyleston and Hollingsworth area.

Diane said the estimated cost of the removal action is $78,500,000 and that EPA determined the conditions warranted early action rather than waiting for a full Superfund remedial process. "These conditions were significant enough that EPA determined they ought to address the situation early before the full Superfund process plays out," she said.

MassDEP did not provide a project schedule beyond noting the early-action approval and that components of the work will include sediment and soil removal, placement of caps and dam-related site work. More detailed planning documents and schedules will emerge as federal and state agencies advance design and contracting.

No formal vote or local funding decision was made at the advisory meeting; the presentation was informational. MassDEP said it will continue coordinating with EPA and affected communities as design and removal activities proceed.