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7-Eleven/Stockton is <br /> February 1989 <br /> were below the laboratory method detection limit for each <br /> sampling event conducted. The results of the total lead analyses <br /> are tabulated on Table 3 (Appendix I) and the laboratory results <br /> are included in Appendix III. <br /> SOIL-VENT SYSTEM <br /> Four vapor-extraction points are located near the under- <br /> ground tank pit and are connected to a high vacuum blower that <br /> removes vapors from the subsurface. The four vapor points are <br /> manifolded to four vapor-phase carbon adsorption canisters to <br /> decrease air emissions to levels deemed acceptable by the San <br /> Joaquin County Air Pollution Control District. <br /> f. <br /> The soil-vent systen was non-operational during the month of <br /> December 1988 due to the anticipated change out of the carbon <br /> treatment system to a Catalytic ScavengerR treatment system. <br /> t..f <br /> Spent carbon was removed in late December, and new carbon was <br /> installed into the system in January. The soil-vent system is <br /> { ' currently operational and is withdrawingvapors at an <br /> ors P approximate <br /> flow rate of 100 cubic feet per minute (cfm) . Photo-ionization <br /> i, detector (PID) monitoring of the two pre-filter vapor-phase <br /> carbon canisters is conducted every two weeks for detection of <br /> I + <br /> carbon breakthrough. Upon detection of hydrocarbon vapors in the <br /> emissions from the two pre-filter carbon canisters, the canisters <br /> are replaced. This method of emission treatment results in <br /> maintenance of non-detectable hydrocarbon emissions from the <br /> soil-vent system. <br /> ,�, Gs�u u�u,u►:k <br /> TECII11YUKA; IaC. <br />