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A S E C ® R Ms Lori Duncan February 9, 2004 Page 4 E and were installed with a 2-inch PVC well casing screened from 77 to 82 feet bgs Extraction well (EW-2) was completed at 43 feet bgs, and was installed with a 6-inch PVC well casing with a stainless steel wire-wrap screen extending from 20 to 40 feet bgs Wells DMW-2, DMW-3, and EW-2 1 are located off-site north across E Harding Way from the site " In August 2002, SECOR submitted a Problem Assessment Report (PAR), which evaluated various remedial alternatives for the site SECOR recommended the installation of a groundwater extraction (GWE) and soil vapor extraction (SVE) system The recommendation included the installation of five additional GWE (EW-3 through EW-7) wells and one additional SVE (SVE-2) well to be utilized as groundwater extraction and soil vapor extraction wells Proposed groundwater extraction and soil I_ vapor extraction were located both on and offsite San Joaquin County approved the remedial recommendations in their letter dated November 7, 2002 ONSITE REMEDIAL ACTION s All onsite remedial wells were installed by November 2002 and remedial system installation at the site was initiated in January 2003 Installation of underground conveyance piping including groundwater .: extraction and soil vapor extraction piping, electrical conduit, well head connections to all onsite remedial wells, and remedial equipment was completed by March 2003 Pacific Gas and Electric completed the installation of natural gas in May 2003 Remedial system start-up and shake down was completed in May 2003 with official remedial start-up on June 14, 2003 ' The remedial system currently consists of a soil vapor extraction (SVE) system and groundwater a extraction system (GWE) The SVE system consists of a Thermtech Vac 50 thermal oxidizer connected to wells SVE-1, SVE-2, MW-1, MW-2, MW-4, and EW-1 The groundwater extraction system consists of submersible extraction pumps in wells EW-1 and EW-6 connected to an air Y' stripper and three 2000 lbs granular activated carbon vessels prior to discharge to the City of Stockton sanitary sewer Discharge of groundwater to the sanitary sewer is permit through the City of Stockton Municipal Utilities Department and permit to operate the thermal oxidizer was issued by San " Joaquin Valley Air Pollution Control District z To date the sod vapor extraction system has removed 20,138 pounds (lbs) of TPHg, 90 lbs of rya benzene, 1,680 lbs of MtBE The groundwater extraction system has pumped 183, 200 gallons of water at an average pumping rate of 0 8 gpm To date the groundwater extraction system has 4 removed 74 8 lbs of TPHg, 3 15 lbs of benzene, and 88 2 lbs of MtBE Sod vapor and groundwater extraction system performance data is included in Tables 2 and 3 ,r CONNECTION OF OFFSITE REMEDIAL WELLS AND SUMMARY OF CURRENT OFFSITE INTERIM REMEDIAL ACTION Connection of offsite groundwater extraction wells EW-2 through EW-5 and EW-7 to the groundwater extraction system and EW-3 and EW-4 to the soil vapor extraction system was proposed by SECOR in the Problem Assessment Report dated August 29, 2002 SECOR obtained a revocable and A encroachment permit from the City of Stockton to complete the installation of the offsite extraction wells, a horizontal boring required to cross Harding Way and trenching to connect the wells SECOR completed the installation of the offsite wells in August 2003 Subsequent installation of the horizontal boring beneath Harding Way and connection of the offsite wells to the onsite remedial system has not been completed for the following reasons k 11ARC0149321workplans\Revised IRAP&WP doc