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. QUARTERLY REPORT APACHE PLASTICS L.P. 2050 East Fremont Street Stockton, CA FOURTH QUARTER 1996 EXECUTIVE SUMMARY This report discusses groundwater and vapor extraction monitoring during the fourth quarter of 1996 at the Apache Plastics manufacturing facility in Stockton, California The report was prepared by Upgradient Environmental Consultants under contract no 96004 The VR Systems vapor extraction unit operated for 86 days (1,945 hours) between October 1 and December 31, 1996, withdrawing approximately 4,978,620 cubic feet of soil vapor In the early part of the quarter, most of the vapors came from the extraction well termed VE-1 "shallow", because the open end of VE-1 "deep" was submerged below the static water level In October, a second extraction well was installed, and thereafter extraction took place from this well (VE-2) and from VE-1 "shallow" Approximately 1,970 pounds of hydrocarbons were destroyed, bringing the estimated total to over 15,400 pounds (2,000 gallons) since inception of remediation in July 1994 The unit's on-board computer monitored all essential parameters except vapor concentration, which was manually monitored by Upgiadient personnel on a weekly basis, using a portable photo- ionization detector These data, along with laboratory analysis of two vapor samples collected in December, were used to assess the efficiency of the system The vapor extraction unit was shut down at the end of the quarter, when the Permit to Operate expired, but remains on site pending regulatory directives Groundwater was monitored in December The depth to groundwater was measured in all six monitoring wells, but only MW-5 was sampled Gasoline, benzene, and other contaminants were detected, but at slightly lower concentrations than in previous quarters As in previous quarters, depth measurements indicate that the water table was not planar, but formed a trough trending southeast across the site at a slope of 0 0015 ft/ft The depth to groundwater averaged almost 56 feet, two feet shallower than in the third quarter • 1