The ROD identifies ex-situ treatment of the 1,4-dioxane and VOC plume as a remedial components of the RD/RA. Due to the mobility of 1,4-dioxane and an inherit threat to a nearby municipal well, USEPA elected to accelerate the cleanup efforts through a Non-Time Critical Removal Action for Groundwater (GW NTCRA), effective July 2016. In order to isolate the plume and cutoff the migration towards Assabet 1A supply
well, a temporary system was installed in May 2017 and operated through May 2019. This system proved hydraulic containment of the plume and successfully cutoff the migration of contaminated groundwater downgradient to the extraction well. As designed and constructed during the GW NTCRA, groundwater extraction from the overburden and bedrock aquifer and ex-situ treatment of VOCs and 1,4-dioxane will continue in the permanent GW Treatment System on site.