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} CVV V9 A S S O C I A T E S I N C around the screen implant from a depth of 20 to 25 feet bgs Bentonite Sand (#8 bentonite) was used to make a 4-foot seal above the filter pack and the wells were grouted to surface grade with Portland cement i Groundwater Remediation Based on an EHD office meeting conducted on April 5, 2000, the EHD and the RWQCB verbally agreed on the use of groundwater extraction and treatment to mitigate the site As noted above, an SVEIIAS system was installed and operated at the site to remediate hydrocarbon-impacted soil and groundwater Over the course of the remediation, rising ' groundwater elevation had submerged a significant portion of contaminated soil below the groundwater table and capillary fringe Under this condition, hydrocarbon-impacted groundwater has remained and the overall influence of the IAS system has demonstrated ' diminishing effectiveness at reduction of dissolved hydrocarbons Areas in the eastern portion of the site and the northwest corner of the site had not demonstrated a sustained reduction of dissolved hydrocarbons Groundwater remained impacted The implications from the set of March 2001 aquifer groundwater extraction tests were the following The groundwater table occurred within the screened interval of the well and the most likely source of the extracted groundwater was from the highly permeable sand, encountered from 20 feet to 30 feet bgs ' Based on the groundwater aquifer pumping test results, AGE recommended remediation by groundwater extraction Based on an estimated radius of influence of at least 35 feet and site specific aquifer characteristics inferred from the pumping test, AGE believed that groundwater extraction from four existing and three additional groundwater extraction wells would effectively stabilize the groundwater plume and prevent migration of petroleum-impacted ' groundwater off site Extracted groundwater would be treated through an on-site groundwater pump-and-treat system The groundwater pump and treat system would utilize granular activated carbon (GAC) to address TPHg and BTEX in extracted groundwater Following ' treatment, water would then be discharged into the City of Stockton under a Municipal Utility District permit Installation Of Groundwater Recovery Wells Between December 2001 and March 2002, three groundwater recovery wells, a groundwater ' treatment system, and associated piping were installed at the site Groundwater remediation system installation and operation were performed in accordance with procedures described in the approved Remedial Action Work Plan Addendum, dated June 28, 2001 ' In December 2001, three soil borings were advanced to a depth of 30 feet bgs Soil borings EW1, EW-2 and EW3 were completed as 6-inch diameter groundwater extraction wells w U71421rwrlslc1osure doc 9 � 1 I