Ex-situ Groundwater

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.

Groundwater Treatment Monitoring Performance Objectives

Maintain Hydraulic Capture

by extracting at the designed rate of approximately 20 gpm and monitoring groundwater elevations.

Hydraulic Capture

continues to be maintained and monitored monthly.

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Observe Decreasing Concentration Trends

by tracking 1,4-dioxane concentration over time.

Decreasing Concentration Trends

decreasing 1,4-dioxane concentrations have been seen in wells downgradient from the extraction well.

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Monitor Treatment System Effectiveness

by tracking the overall influent and effluent 1,4-dioxane over time.

Treatment System Effectivness

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