CS-10 PLUME RESPONSE ALTERNATIVE A
Alternative A would use extraction, treatment, and
reinjection (ETR) technology. This alternative is designed for maximum plume capture.
Extraction fences (a fence is a series of wells) would be located along the leading edge
of the plume, including the area adjacent to Ashumet Pond.
The attached figure illustrates the conceptual layout of
ETR fences for Alternative A, described below.
Components of the Alternative
Northwest Extraction Fence
- Captures a portion of the plume before it migrates out of
the CS-10 plume footprint and deeper into the aquifer, allowing for more efficient
downgradient extraction.
- Minimizes impacts to groundwater flow directions for the
adjacent Landfill-1 (LF-1) plume.
- Reinjection fences are not located near the northwest
extraction fence. This avoids the potential for spreading the plume by reinjecting treated
water over the plume.
Southwest Extraction Fence
- Captures the leading edge of the western lobe of the plume.
- Captures the upgradient portion of the Chemical Spill 4
(CS-4) and Fuel Spill 28 (FS-28) plumes.
West Reinjection Fence
- Balances groundwater flow by returning treated water to the
aquifer since it was removed by the northwest and southwest extraction fences.
Specifically designed to minimize disturbance of the LF-1 and CS-4 plumes.
Southern Extraction Fence
- Treats the central portion of the plume.
Main Reinjection Fence
- Balances groundwater flow by returning treated water to the
aquifer since it was removed by the southern extraction fence. Specifically designed to
minimize disturbance to the Ashumet Valley plume.
Ashumet Pond Extraction Fence
- Treats the portion of the plume upgradient of Ashumet Pond.
The fence is located within about 100 feet of the shoreline of Ashumet Pond.
East Reinjection Fence
- Balances groundwater flow by returning some of the water
that is intercepted by the fence along Ashumet Pond.
- Balances the reinjection of water west of the CS-10 plume.
Considerations
- Plume capture is highest among the alternatives currently
under consideration.
- The potential for discharge of the plume to Ashumet Pond and
for further migration of the plume beneath the pond is reduced compared to the other
alternatives under consideration.
- There are potential effects of the Ashumet Pond extraction
fence on sensitive ecological habitats adjacent to the pond, requiring significant
mitigation procedures and plans.
- There are potential socioeconomic impacts associated with
the installation and operation of the system within the residential area southeast of
Sandwich Road.
- There is a high probability that gaining access to the
required properties would delay the installation and startup of the system
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