Laserfiche WebLink
:f <br /> CSm10 PLUME RESPONSE ALTERNATIVE F <br /> Alternative F uses a combination of ETR and RwT. ■ Specifically designed to minimize disturbance <br /> It is designed to improve plume cleanup, with some to the Ashumet Valley plume. <br /> consideration of property ownership, access, and <br /> impacts. Extraction fences would be Sandwich Road Extraction Fence <br /> ecological p <br /> located along the leading edge of the plume, except ■ Captures the portion of the CS-10 plume up- <br /> for the area adjacent to Ashumet Pond. gradient of Sandwich Road. <br /> Recirculating wells would be placed near the edge ■ Extraction wells immediatel north of Sandwich <br /> and and extraction wells would be laced Y <br /> of thep p Road provide expedited removal of highly <br /> along Sandwich Road. Several wells would be contaminatedoundwater. <br /> placed immediatelynorth of Sandwich Road to � <br /> expedite removal of highly contaminated Ashumet Pond Recirculating Wes <br /> groundwater. ■ Captures some of the plume downgradient from <br /> a attached figure illustrates the conceptual layout Sandwich Road and upgradient of Ashumet <br /> ThP Y <br /> of ETR fences and recirculating wells for Alterna- Pond. Property access issues would not allow <br /> tive F,described below. for spacing of recirculating wells sufficient to <br /> achieve complete capture. <br /> Components of the Alternative <br /> r ■ These wells are expected to operate only 3-5 <br /> Northwest Extraction Fence Years. <br /> ■ Improves capture of a portion of the plume East Reinjection Fence <br /> north of the fence that is relatively highly <br /> contaminated, preventing some contaminants • Balances groundwater flow by returning some <br /> from migrating to low--conductive silts. of the water that would be intercepted by the <br /> g g low-conductivity <br /> Sandwich Road extraction fence. <br /> ■ Minimizes impacts to groundwater flow <br /> fume. • Balances the reinjection of water west of the <br /> directions for the adjacent LF-I p <br /> CS-10 plume. <br /> ■ Reinjection fences are not located near the <br /> northwest extraction fence. This avoids the Considerations <br /> u' potential forspreading the plume by reinjecting • High degree of plume cleanup/mass reducti <br /> on. <br /> treated water over the plume. <br /> ■ Installation and operation of recirculating wells <br /> Southwest Extraction Fence near the Ashumet Pond shoreline results in <br /> 0 Captures f plume. fewer ecological and socioeconomic impacts <br /> p es the western lobe o the <br /> than extraction wells. <br /> ■ Captures,the upgradient portion of the CS-4 and <br /> FS-28p lumes. ■ The portion of the plume between Sandwich <br /> Road and Ashumet Pond would be subject to <br /> West Rein'ection Fence contaminant mass reduction, but some of the <br /> Balances groundwater flow b returning treated plume would not be captured and could migrate <br /> g Y g <br /> water to the aquifer removed by the northwest to and/or beyond the pond. <br /> and southwest extraction fences. . The installation of recirculating wells could <br /> ■ Specifcall desi ned to minimize disturbance affect sensitive ecological habitats adjacent to <br /> Y g <br /> of the LF-I and CS-4p lumes. the pond, requiring some mitigation procedures <br /> and plans. <br /> Southern Extraction Fence <br /> ■ There is a potential socioeconomic impact asso- <br /> • Treats the central portion of the plume. ciated with the installation and operation of the <br /> Main Rein'ection Fence recirculating well system in the residential area <br /> • southeast of Sandwich Road. <br /> Balances groundwater flow by returning treated <br /> It <br /> water to-the aquifer removed by the southern • is possible that gaining access to all of the <br /> q <br /> extraction fence. required properties could delay the installation <br /> and startup of the recirculating well element of <br /> the system. <br /> 5 <br /> } <br />