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S E C 0 R Circle K Store 08671 August 31, 2005 Page 6 collected at the beginning and end of each daily extraction period for that well This totaled to be three extraction events for SVE-1 and one for SVE-2 The highest soil vapor concentrations of TPHg, and toluene were measured while extracting from well SVE-1, at 180 parts per million by volume (ppmv), and 1 7 ppmv, respectively Benzene & ethyl- benzene were not detected in either well The highest soil vapor concentrations of total xylenes were measured while extracting from well SVE-1 at 0 33 ppmv MtBE was measured while extracting from well SVE-1 at a maximum of 4 2 ppmv For SVE-1, TPHg decreased each day during the removal, rose up after the first day, then declined to non detectable levels at the end of the test Toluene decreased after the first day and was not present in further samples Total xylenes were detected at the end of the second day for SVE-1 but were not detected at the end of the test SVE MASS REMOVAL RATES The total mass of TPHg, benzene, and MtBE removed during the test were estimated using the average combined influent vapor analytical results, average well field flow rates, and the time between each sample The calculated TPHg, benzene, and MtBE mass removed during the SVE test were approximately 0 57 pounds, 0 0028 pounds, and 0 0149 pounds, respectively The calculations of mass removal are presented in Table 5 SOIL VAPOR RADIUS OF INFLUENCE • The radius of influence (ROI) was determined graphically by plotting the average lateral distance from the extraction well to the monitoring well, versus the initial applied vacuum and resulting induced vacuums An induced vacuum greater than 0 1 in H2O provides evidence that there is a sufficient level of vacuum to induce airflow in the area (Suthan S Suthersan, Remediation Engineering Design Concepts, 1997, pp 54) Therefore, an induced vacuum of 0 1 in H2O was used to represent the theoretical minimum induced vacuum defining "influence" from the applied vacuum The distance at which a "trend line" of the data crosses 0 1 in H2O is the estimated radius of influence for each extraction well Induced vacuum readings were obtained from surrounding monitoring wells during extraction from each of the wells The average vacuum induced for each monitoring well was used for the ROI determination for each extraction well The ROI for extraction wells SVE-1 is less than approximately 13 feet, the distance between SVE-1 & MW-1S as the induced vacuum reading was 0 0 in H2O The ROI for extraction wells SVE-2 is approximately 9 feet, the distance between SVE-2 & MW-4S as the average induced vacuum reading was 1 35 in H2O CONCLUSION AND RECOMENDATIONS Based on the data collected during the SVE test, SVE technology is not effective at removing hydrocarbons from the soil beneath the site because for a small radius of influence and low mass removal rates The estimated daily mass removal rates from the well used for this SVE test range from 1 03 pounds per day of TPHg in the middle of the test to 0 25 pounds per day of TPHg at the end of the test, and 0 0298 pounds per day of • MtBE at the beginning of the test to 0 0141 pound per day of MtBE at the end of the test m