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ri "f <br /> DISCUSSION <br /> Results of this monitoring event indicated that levels of dissolved gasoline hydrocarbons are consistent <br /> with levels detected during previous sampling events The groundwater gradient and direction of <br /> groundwater flow were also consistent with previous data Groundwater elevation Increased <br /> approximately 2 75 feet from the previous sampling event (February 1996) <br /> The SVE system is operating efficiently to reduce petroleum hydrocarbon Impact to soil and <br /> groundwater A total of 866 pounds of TPHG were removed during the second quarter of 1996 A <br /> cumulative amount of 19,938 pounds of TPHG has been removed since commencing SVE activities (see <br /> Table 4) Figures 4 and 5 present the rate of TPHG concentration decline over time and the cumulative <br /> mass of TPHG removed over time, respectively <br /> Air sparging was Initiated towards the end of the first quarter and continued into the second quarter <br /> Spargmg significantly increased the dissolved oxygen levels in air sparge well AS-2 (see Table 5) <br /> EMCON will continue to monitor the effects of air sparging during the third quarter 1996 <br /> EMCON will continue to maintain and optimize the system <br /> ATTACHMENTS. <br /> Table 1 Groundwater Monitoring Data <br /> Table 2 Operational Uptime Information <br /> Table 3 Results of Analyses of Air Samples and Flow Rates <br /> Table 4 Extraction and Emission Rates <br /> • Table 5 Dissolved Oxygen Levels <br /> • Figure 1 Site Location Map <br /> • Figure 2 Generalized Site Plan <br /> • Figure 3 Groundwater Contour Map (May 30, 1996) <br /> • Appendix A Sampling and Analysis Procedures <br /> • Appendix B Laboratory Analytical Reports and Chain-of-Custody Records <br /> • Appendix C Field Data Sheets <br /> cc Elizabeth Thayer, California Regional Water Quality Control Board <br /> SACH\P)0\0805\08051140 6BS-96\c1b L <br />