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Tosco Corporation a subsidiary of Ptulhps Petroleum Company 6 <br /> Tosco Station#t t 193,3202 West Hamner Lane,Stockton,CA March 7,2002 <br /> duration of the test The calculated TPHg, benzene, and MtBE mass removed during the <br /> DPE test were approximately 8 11 pounds, 0 17 pounds, and 5 26 pounds, respectively <br /> (Table 4 and Figure 3) <br /> Additionally, during the tests approximately 26,210 gallons of groundwater were <br /> extracted from the site Extracted groundwater was temporarily stored in a holding tank, <br /> prior to disposal at Tosco's Refinery in Rodeo, California <br /> Soil Vapor Radius of Influence <br /> The radius of influence was determined graphically by plotting the average lateral <br /> distance from the test well to the observation wells, versus the initial applied vacuum (in <br /> Hg) and the resulting induced vacuums (in of H2O), from Table 1 An induced vacuum <br /> of 0 1 inches H2O was used to represent the theoretical minimum induced vacuum <br /> defining "influence" from the applied vacuum The distance at which a"best fit" line <br /> formed by the data crosses 0 1 inches H2O is the estimated radius of vacuum influence for <br /> each test well Based upon this data, the estimated radius of influence for test well VW-1 <br /> was 41 feet (Figure 4) and for test wells VW-1, MW-1R, and MW-2R, the combined <br /> estimated radius of influence is 24 feet (Figure 5) <br /> SUMMARY OF FINDINGS <br /> On November 26`h through November 30th, 2001, SECOR performed DPE event at the <br /> site The results of the DPE event are as follows <br /> • DPE was conducted at vapor extraction flow rates ranging between 10 90 cfm <br /> to 42 86 cfm, and at vacuums ranging from 14 to 25 inches of mercury <br /> • Groundwater extraction flow rates ranged from 0 01 gpm to 6 2 gpm <br /> • MtBE influent concentrations declined from 200 ppmv to 86 ppmv <br /> • During the DPE event approximately 8 11 pounds of TPHg, 0 17 pounds of <br /> benzene, and 5 26 pounds of MTBE were extracted from the soil and <br /> groundwater beneath the site <br /> CONCLUSIONS <br /> Based on the data collected during the DPE tests, DPE is not an effective remedial <br /> alternative for this site <br /> • <br />