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9110 Thornton Road, Stockton, Calrforrna April 27, 1994 <br /> The Southland Corporation Page 3 <br /> E Between February 1987 and January 1991, a soil vapor extractions stem was <br /> p y <br /> installed and operated by Vapor Extraction Technology, Inc The soil vent system <br /> removed an equivalent of 576 gallons of separate-phase hydrocarbons <br />' Historical groundwater monitoring and sampling data are summarized in Table 1 The analytical <br /> results for historical sampling of soil are summarized in Table 2 Figures 3 through 6 Illustrate <br /> historical and current petroleum hydrocarbons distribution in soil and groundwater at the site <br />' Hydrographs for selected monitoring wells, based upon historical groundwater monitoring data are <br /> included as Figures 7 through 9 <br /> AQUIFER PUMPING TEST <br />' In March 1988, a 24-hour aquifer pumping test was performed to acquire data with which the e aquifer <br /> parameters of transmissivity, (7) and storativity (S) were estimated for the groundwater remediation <br />' wells The results of the test, including calculations for T, S, and zone of capture, were presented in <br /> Groundwater Technology's Quarterly Update Report, dated April 1988, and are included in this <br /> report in Attachment 3 <br />' SOIL VAPOR EXTRACTION TEST <br /> On January 13, 1994, a soil vapor extraction test was conducted to determine if hydrocarbons are <br /> present in the subsurface sod, to estimate radius of capture of vapor extraction, and to estimate <br /> potential hydrocarbon mass extraction rates <br />' Prior to startup of the test, SJCPHS and the CRWQCB-CVR were notified of the scheduled test date <br />' Tests were conducted on monitoring wells MW-1 through MW-5, MW-8, MW-10, MW-12, pumping <br /> wells PW-2 and PW-3, and vadose wells VP-1, VP-2 and VP-3 (Figure 2) The sod vapor extraction <br /> tests were conducted by applying vacuum at each of the selected wells utilizing a 1 5-horsepower <br />' regenerative blower <br /> Monitoring well MW-1 was arbitrarily selected as the primary test well and was tested for a longer <br />' period of time (70 minutes) relative to the remaining wells that were tested (approximately <br /> 15 minutes) The reason for this was the time constraint to monitor all test parameters, such as <br />' induced vacuum, velocity and flow rate during the testing of ten wells Therefore, radius of capture, <br /> velocity and flow rate obtained from the test for MW-1 are here considered as a general <br /> representation for the entire site <br /> =W GROUNDWATER <br />' I,� TECHNOLOGY <br />