DPW Yard PFAS Investigation and Remediation
Weston & Sampson was selected by the Town of Chelmsford to provide Licensed Site Professional (LSP) and remediation services in connection with the detection of per- and polyfluoroalkyl (PFAS) compounds in the groundwater resources beneath the town’s Department of Public Works (DPW) yard. The town had detected several PFAS compounds at cumulative concentrations exceeding the corresponding maximum contaminant level (MCL) of 20 nanograms per liter (ng/L) in existing on-site monitor wells. Due to the proximity of the site to a nearby public drinking water supply, the town enlisted Weston & Sampson to assist with investigations and remediation.
Weston & Sampson prepared and submitted the necessary IRA Work Plan as required by the Massachusetts Contingency Plan (MCP) and implemented the approved evaluations. The evaluations included identifying and delineating possible source areas and routes for potential off-site migration of the detected PFAS. It was determined that past maintenance activities may have been the source and that it had impacted primarily the groundwater due to the inherent chemical characteristics of the detected compounds. Further on-site and off-site delineation of PFAS in groundwater were completed and indicated that the PFAS plume had migrated within the local sand and gravel aquifer beyond the DPW property boundaries, consistent with the general direction of groundwater flow. The bulk of the residual source of the plume still occurred within the DPW property boundaries.
Based on these results, Weston & Sampson proposed the implementation of a recovery well located proximal to the on-site source that would hydraulically control the plume and divert the impacted groundwater to an on-site treatment facility. After approval of the plan by MassDEP, one recovery well was installed and connected to a treatment system consisting of filtration, GAC, and resin vessels. The treated PFAS-free water was subsequently returned to the local groundwater resources to provide further hydraulic containment of the plume and ensure minimal impact to the local groundwater resource recharge capacity.