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i <br /> S EC ® R <br /> Mr Mike Infurna <br /> October 29, 2004 <br /> Page 5 <br /> RECOMMENDATIONS <br /> SECOR will install deep monitoring wells and submit results of the assessment The site should <br /> continue to be monitored and sampled on a quarterly basis to verify the stability of the plume <br /> beneath the former 76 Station Joint monitoring and sampling with the upgradient ARCO station will <br /> continue so that regional groundwater flow and chemical isoconcentration maps can be generated <br /> CHARACTERIZATIONIREMEDIAL STATUS <br /> Soil contamination delineated? Yes <br /> Dissolved groundwater delineated? No <br /> Free product delineated? NIA <br /> Current phase of project? Assessment/Monitoring <br /> Frequency of sampling? Quarterly <br /> Soil remediation in progress? No <br /> Anticipated start date? NIA <br /> Anticipated completion date? NIA <br /> Shallow zone groundwater gradient? Variable <br /> • Deep zone groundwater gradient? 0 004 ft/ft Northeast <br /> NEIGHBORING SITE ACTIVITIES <br /> The ARCO service station, located at 16 E Harding Way, upgradient of the Former 76 station appears <br /> to be affecting groundwater concentrations within wells at the Former 76 Station The following is an <br /> outline of remedial efforts at ARCO 4932 <br /> Soil Vapor and Groundwater Extraction <br /> Soil Vapor Extraction <br /> SVE was started on June 14, 2003 The SVE portion of the DPE system is comprised of 6 SVE <br /> wells (SVE-1, SVE-2, MW-1, MW-2, MW-4, and EW-7) and a Thematech VAC 50 thermal/catalytic <br /> oxidizer (Cat-Ox) as the abatement device Approximately 262 pounds (lbs) of TPHg, 1 5 lbs of <br /> benzene, and 90 lbs of MtBE were removed during the third quarter 2004 An estimated 23,566 5 <br /> lbs of TPHg, 99 lbs of benzene, and 1,971 lbs of MtBE have been removed since remediation was <br /> initiated at the site <br /> t , <br /> Groundwater Extraction System <br /> The GWE portion of the system is comprised of submersible pumps installed in wells EW-1 and EW- , <br /> 6 and "slurp" tubes installed in wells MW-4 and EW-7 Offsite extraction well EW-7 was connected <br /> to the system and brought online in June 2004 During the third quarter 2004, the GWE system <br /> pumped and treated approximately 203,800 gallons of groundwater, removing approximately 6 7 lbs <br /> of TPHg, 0 7 lbs of benzene, and 6 0 lbs of MtBE An estimated 109 5 lbs of TPHg, 3 95 lbs of <br /> benzene, and 135 4 lbs of MtBE have been removed by GWE since the remedial system began <br /> operating at the site <br /> 11conocoPhiihps\Tosco Marketing144091Qssrs1200413Q2004_QSR doc SECOR International incorporated <br />