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• 0 thereby making the vapors accessible to vapor extraction The extracted vapors can then be • treated above ground in the same way as vapors extracted from the vadose zone Sparging can also be used to provide oxygen to stimulate hydrocarbon degradation by naturally occur ing microbes, a technique known as bioventing The air sparging test will utilize the soil vapor destruction unit described in section 4 3 A regenerative blower on the destruction unit will be connected to the sparging well, and Fir will be injected at a rate of between 2 and 5 CFM Sparging will begin at the conclusion of the 3-hour SVE test, and will be conducted for four hours A Tedlar bag sample will be collected a the end of the test, and PID measurements will continue at 30-minute intervals The results will be used to analyze the benefits of using air sparging in combination with vapor extraction i 5.0 SENSITIVE RECEPTOR SURVEY The site is located in a mixed commercial-industrial area of Stockton, and underground utility lines and other man-made structures are abundant in the area There may also be domestic and industrial wells in the vicinity, although the area is now on city water and sewer lines These features could potential affect or be affected by migration of the groundwater contamination plume at the Valley Motors site Therefore, following the drilling of the off-site monitor wells, Upgradient will perform a survey to identify potential contaminant receptors In addition to a drive-by inspection of the area, Upgradient will review the well files at the California Department of Water Resources and contact local utility companies for maps of their facilities 6 0 AQUIFER TESTING In order to comply with Appendix A of the Tri-Regional Board Guidelines for R elimmary Investigation and Evaluation of Underground Tank Sites, a 24-hour constant-rate groundwater pumping test of well VM-1 will also be conducted The purpose of this test will be to obt,un a more j accurate determination of the hydraulic conductivity, as well as other important data about the aquifer, such as transmissivity and drawdown information, so that the feasibility of groundwater extraction as a remedial technology can be evaluated The other monitor wells will be used as observation wells during the test Transducers will be lowered into these wells and connected to a datalogger so that drawdown can be moan ored over time and the radius of influence of VM-1 can be determined The extracted groundwater will be stored in a Baker tank, but the volume is unknown at this time If the previously-conducted bioremediation feasibility test was successful, the extracted wafer will be treated in the above-ground bioreactor and reinfected into the aquifer If the bioremediation test was unsuccessful, the extracted water will be run through a carbon canmster system before being discharged to the city sewer i