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• Atlantic Richfield Company Page 13 <br /> ARCO Station No 4932,Stockton,California August 29 2002 <br /> 5.1.1 Summary of Findings <br /> • The five-day MPE test produced vapor extraction flow rates ranging between 32 7 <br /> and 99 2 scfm, from MW-4 and SVE-1, and at vacuum pressures ranging between <br /> 5 5 to 25 inches of water column from MW-4 and SVE-1 <br /> • Based on the responding Induced vacuums up to 89 feet away, the calculated radii <br /> of influence for the test ranged between 46 7 feet and 89 2 feet <br /> • During the test approximately 544 3 pounds of TPHg, 19 5 pounds of benzene, <br /> and 440 pounds of MtBE were extracted from the soil beneath the site, as <br /> calculated from laboratory results and field FID readings that consistently <br /> exceeded 10,000 ppmv <br /> 5.1.2 Conclusions <br /> Based on the data collected during the DPE test, DPE technology is capable of removing <br /> high concentrations of hydrocarbons from the soil beneath the site The estimated daily mass <br /> removal rates following the Initiation of vapor extraction range from 18 to 26 pounds of <br /> TPHg and up to 62 pounds of MtBE While the rate of hydrocarbon removal is expected to <br /> decline over time, the DPE would significantly reduce the mass of petroleum hydrocarbons <br /> . present in the subsurface However, due to the low groundwater extraction rates during <br /> feasibility testing, DPE will not induce significant hydraulic control of the hydrocarbon <br /> plume <br /> 5.2 Aquifer Pumping Test <br /> A step drawdown and aquifer pumping test was performed at the site by SECOR on April 2 <br /> through 4, 2002 The results are summarized In the SECOR report titled Site Assessment and <br /> Aquifer Testing Results dated June 7, 2002 The results of this test are summarized In this <br /> section <br /> 5.2.1 Summary of Findings <br /> The purpose of this test was to evaluate hydrogeologic conditions beneath the site and to <br /> assess if groundwater extraction is a feasible alternative for remediating the dissolved <br /> petroleum hydrocarbon and MtBE plume in groundwater <br /> Step-drawdown and constant-rate pumping tests were performed between April 2 and 4, <br /> 2002 The step-drawdown test was conducted to determine the optimum pumping rate for <br /> the constant-rate pumping test, and the constant-rate pumping test was performed to estimate <br /> aquifer parameters Including transmissivity (T), storativity (S), and hydraulic conductivity <br /> (K) <br /> J <br /> 11ARCO\49321PAR\PAR doe <br />