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QUARTERLY REPORT <br /> 2050 East Fremont Street <br /> tFOURTH QUARTER 1995 _ <br /> APACHE PLASTICS L.P. <br /> ' Stockton, CA <br /> tEXECUTIVE SUMMARY <br /> This report discusses groundwater and vapor extraction monitoring during the fourth quarter of 1995 <br /> ' at the Apache Plastics manufacturing facility in Stockton, California The report was prepared by <br /> Upgradient Environmental Consultants under contracts no 94116 and 95004 <br /> ' The VR Systems vapor extraction unit operated for a total of 1,816 hours between October 1 and <br /> December 31, 1995, withdrawing approximately 4,263,000 cubic feet of soil vapor from the two <br /> extraction wells The unit was operated and maintained by Apache Plastics personnel It operated for <br /> ' 86 days during the quarter The unit's on-board computer monitored all essential parameters except <br /> vapor concentration, which was manually monitored by Upgradient personnel on a weekly basis, using <br /> a portable photo-ionization detector These data, along with laboratory analysis of a vapor sample <br /> t collected in December, were used to assess the efficiency of the system With the approval of Mrs <br /> Diane Hinson of San Joaquin County Environmental Health, the vapor sample was also analyzed for <br /> the following inert gases oxygen, carbon dioxide, nitrogen, and methane in order to identify the non- <br /> combustible gas(es)that appeared to interfere with efficient operation of the internal combustion engine <br /> during the early part of the quarter An exceptionally high nitrogen concentration was detected, <br /> suggesting that an excess of nitrogen inhibited efficient combustion The source of the nitrogen is <br /> ' unknown <br /> Groundwater was also monitored in December Water was present in all six monitoring wells, and all <br /> ' were sampled Water was initially present in the deep extraction well, but the well did not recharge <br /> after purging and the well was not sampled As in the previous three quarters, gasoline and benzene <br /> ' were detected in MW-5, but at slightly lower concentrations Depth measurements indicate that the <br /> water table was not planar, but formed a trough trending southeast across the site at a slope of 0 0015 <br /> ft/ft The depth to groundwater averaged 61 feet <br /> 1 <br /> � 1 <br />