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QUARTERLY REPORT APACHE PLASTICS L.P. 2050 East Fremont Street Stockton,CA SECOND QUARTER 1997 ' EXECUTIVE SUMMARY This report discusses groundwater and vapor extraction monitoring dunng the second quarter of 1997 at the Apache Plastics manufacturing facility in Stockton, California The report was prepared ' by Upgradient Environmental Consultants under contract no 97004 ' The VR Systems vapor extraction unit operated for 89 days (2,055 hours) between April 1 and June 30, 1997, withdrawing approximately 4,968,000 cubic feet of soil vapor The unit's on-board computer monitored all essential parameters except vapor concentration, which was manually monitored by Upgradient personnel during operating weeks, using a portable photo- ionization detector These data, along with laboratory analysis of two vapor samples collected in March,were used to assess the efficiency of the system Groundwater was monitored in June The depth to groundwater was measured in all six monitoring *� wells Samples were collected from MW-5 and from the out-of-use vapor extraction well (VE-1 "deep") Gasoline, benzene, and other contaminants were detected at moderated concentrations in VE-1 Gasoline was also detected in MW-5, at the highest concentration since May 1996 Benzene and other volatile compounds were not detected The high TPH-g concentration may be due to not purging the well prior to sampling The decision to not purge the well was based on the recent suggestion by the State Underground Storage Tank Fund to omit purging 1 As in previous quarters, depth measurements indicate` that the water table was not planar, but formed a trough trending across the site However, there has been a change in the trend of the axis ' of the trough Rather than southeast, it presently trends east-northeast at a slope of 0 0015 ft/ft The depth to groundwater averaged 51 feet, one foot shallower than in the first quarter 1 ' S r