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QUARTERLY REPORT <br /> APACHE PLASTICS L.P. <br /> l <br /> 2050 East Fremont Street <br /> rStockton,CA <br /> FIRST QUARTER 1997 <br /> ' EXECUTIVE SUMMARY <br /> This report discusses groundwater and vapor extraction momtonfig during the first quarter of 1997 <br /> at the Apache Plastics manufacturing facility in Stockton, California The report was prepared by <br /> Upgradient Environmental Consultants under contract no 97004 <br /> t The VR Systems vapor extraction unit operated for 36 days (585 hours) between January 1 and <br /> March 31, 1997, withdrawing approximately 1,175,000 cubic feet of soil vapor According to prior <br /> agreement with the San Joaquin Valley Air Quality Managment District, the unit was shut down in <br /> t early January until the Permit to Operate was extended for 1997 When the unit was restarted on <br /> February 6, it ran erratically for several days and vapor flow could not be sustained The unit was <br /> repaired in early March and was returned to operation in mid-March <br /> ' The unit's on-board computer monitored all essential parameters except vapor concentration, which <br /> was manually monitored by Upgradient personnel during operating weeks, using a portable photo- <br /> ionization detector These data, along with laboratory analysis of two vapor samples collected in <br /> March, were used to assess the efficiency of the system <br /> Groundwater was monitored in March The depth to groundwater was measured in all six <br /> monitoring wells, and samples were collected from each of these and from the out-of-use vapor <br /> extraction well (VE-1 "deep") Gasoline, benzene, and other contaminants were detected at <br /> imoderated concentrations in VE-1 Gasoline was also detected in MW-5, at half the concentration <br /> found in previous quarters, but benzene was not detected Benzene, toluene, and xylene were <br /> reported in MW-4 for the first time, but concentrations were very low and Upgradient suspects <br /> laboratory error <br /> ' As in previous quarters, depth measurements indicate that the water table was not planar, but <br /> formed a trough trending southeast across the site at a slope of 0 0015 ft/ft The depth to <br /> groundwater averaged almost 52 feet, four feet shallower than in the fourth quarter of 1996 <br />