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Steven Sasson -2- February 5, 1996 In January 1994, CRC pumped as much hydraulic fluid as possible from the borehole The hydraulic fluid was analyzed and no polychlorinated biphenyls (PCBs) were detected (CRC 1994) The hydraulic casing, which contained the piston used to move the elevator car, was located in a 7-inch diameter soil boring with no secondary containment The length of the hydraulic sleeve, which was burred within the elevator pit area, was approximately 12 feet The hydraulic sleeve and piston were removed and there was a partial collapse of the borehole (CRC 1994) In February 1994, CRC performed a limited subsurface investigation in the area of the elevator pit The objective of the subsurface soil investigation and the subsequent ground water sampling was to estimate the extent of soil and ground water contamination, both laterally and vertically, and to further investigate remediation options (CRC 1994) A preliminary site characterization indicated that the majority of hydraulic fluid contamination was in the upper 6 feet of soil immediately below the bottom of the elevator pit The bottom of the pit was approximately 4 5 feet below grade Three core probes were drilled in the floor of the elevator pit, an area approximately 6 5 feet by 9 5 feet, and three cores were drilled outside the elevator pit area from 10 to 20 feet from the central source (CRC 1994) CRC reviewed regional ground water elevation in the area and estimated that ground water would be at a,depth of approximately 25 feet bgs, however, ground water was encountered at a depth of less than 10 feet bgs (CRC 1994). Regional gradient and bearing of flow are 0 01 foot/foot and north 45 degrees west, respectively (Geological Technic Incorporated [GTI] 1995a) On May 11, 1994, CRC submitted a workplan to the San Joaqum County Public Health Services (SJCPHS) for soil remediation and ground water investigation (CRC 1994) The workplan was implemented, and on January 19, 1995 CRC submitted the Soil Excavation Report and Groundwater Investigation (CRC 1995) for the site According to this report, the excavation was conducted at one 9-foot by 6-foot area of hydraulic fluid-contaminated soil The ground water in the borings was pumped out with a submersible pump in an effort to remove as much floating hydraulic fluid as possible from the excavation Over 2,000 gallons of hydraulic fluid- contaminated ground water were pumped out of the excavated area (CRC 1995) Soil samples were obtained from the bottom of the excavation and analyzed for total petroleum hydrocarbons (TPI) as hydraulic fluid usmg Modified USEPA Method 8015 to confirm that the contaminated soil had been removed to the extent technically feasible or practical The laboratory analytical results of the confirmatory soil samples indicated that the majority of the hydraulic fluid was removed and that negligible levels of hydraulic fluid were detected at the bottom of four borings The remainder of the fifteen soil augured areas showed non-detect levels of TPH CRC estimated, using 500 parts per million (ppm) as an average residual level, that approximately 12 7 gallons of hydraulic fluid were left in place A ground water investigation followed the excavation work and was completed on December 16, 1994 (CRC 1995). Three ground water monitoring wells were installed and ground water samples were collected for analysis The results of the ground water investigation showed non-detect levels of TPH as hydraulic fluid in all three monitoring wells On the basis of the analytical