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Ms Carol Oz Project 880-040 IA December 5, 2000 Page 4 of 6 Interstate-5 overpass Based on conversations with Ms Carol Oz with the SJCPHS/EHD, the well was abandoned as part of the construction of the new Interstate 5 on and off ramps and is no longer a potential receptor or a vertical conduit Cruz Brothers utility locating company performed a subsurface utility survey to locate all underground utilities at the site that may act as potential conduits for groundwater migration Locations of underground utilities present at the site are shown on Figure 4 FINDINGS Subsurface Conditions Soils encountered during drilling (maximum explored depth of approximately 30 feet bgs) consisted of interbedded sands, silty sands, sandy silts, sandy clays, and clays A more complete description of the subsurface lithology is shown on the boring logs presented in Attachment B Depth to groundwater is approximately 14 feet bgs Groundwater onsite is flowing to the north- northeast at a magnitude of 0 0026 feet/feet Groundwater elevations and contours are presented on Figure 5 Soil Analytical Results Geoprobe Investigation Concentrations of TPH-g reported during the Geoprobe® investigation ranged from 1,110 parts per million (ppm) in GP-1 at 28 feet to 83,700 ppm in GP-1 at 24 feet TPH-g was not detected in soil samples collected from GP-3, GP-4, and GP-5 Benzene was reported in GP-2 at 16 feet and 20 feet at concentrations of 0 0256 and 0 14 ppm, respectively Benzene was not reported in any other Geoprobe® soil samples MtBE was confirmed by EPA Method 8260 in samples collected from GP-2 at 16 and 20 feet, from GP-3 at 16 feet, and GP-4 at 16 feet Confirmed MtBE concentrations ranged from concentrations of 0 628 ppm in GP-4 at 16 feet to 2 60 ppm GP-2 at 20 feet Geoprobe soil analytical data is summarized in Table 1 and on Figure 6 Laboratory reports with chain-of-custody (COC) documentation is included in Attachment D Monitoring Well Installation TPH-g and benzene were reported in only one soil sample (MW-1 at 15 feet) collected during monitoring well installation at concentrations of 4 68 ppm and 0 152 ppm, respectively The Presence of MtBE was confirmed by EPA Method 8260 in soil samples from MW-1 at 15 feet, MW-2 at 15 feet, and MW-3 at 10 feet at concentrations of 6 54 ppm, 6 41 ppm, and 1 03 ppm, respectively Petroleum hydrocarbons were not reported in samples collected from 25 feet bgs tiacDP_ILVAC I�Pncon4uomc,,�sul rpgldalaLShn e"rolac„miwlNso 0401Aaadtx IT CORPORATION