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Monitoring well Installation Report-Tosco(Former BP)SS#11195,Lathrop California July 24,2002 surveyed by Virgil Chavez Land Surveying of Vallejo, California(Licensed California Land Surveyor No. 6323). Top of casing (TOC) elevations were measured relative to MSL, and the-horizontal locations of the wells were measured using the Global Positioning System (GPS). Well casing elevation data are presented in Table 1. A copy of the surveyor's report is included in Appendix D. 3.4 Waste Disposal Drill cuttings were placed on and covered with plastic sheeting and stored at the site pending disposal. After completion of drilling, one four-point composite disposal characterization sample was collected from the drill cuttings and submitted to the laboratory for compositing and analysis. The analytical results from the composite soil sample were submitted to Allied Waste's Forward Landfill in Manteca, California, for disposal. On June 27,2002,the drill cuttings were removed from the site and transported to Forward Landfill in Stockton, California, by Denbeste Trucking of Windsor,California,under disposal.approval No. 2096. A copy of the Forward Landfill,acceptance letter is included in Appendix D. 3.5 Laboratory Analysis Selected soil samples were submitted to Sequoia Analytical in Walnut Creek, California (FLAP #1271) and groundwater samples were sent to Severn Trent Services in Pleasanton California(FLAP t=< : #2496), for analysis. Soil and groundwater samples were analyzed for TPHg,BTEX, ethanol, TBA, MtBE, DIPE, ETBE, 1,2 DCA, TAME and EDB by EPAMethod 8260B. The drill cuttings composite sample was analyzed for TPHg, BTEX, and MtBE by EPA Methods 801518021, and for total lead by EPA Method 6010B. Copies of the laboratory analytical reports and chain-of-custody forms are included in Appendix E. 4.0 RESULTS 4.1 Subsurface Conditions Groundwater was encountered in the well borings during drilling at depths ranging from approximately 8 to 10 feet bgs. Soil encountered during drilling consisted primarily of silty sand, poor to well graded sand, and silt. In well borings 1\4W-13, MW-15, and 1\4W-16, silty sand was encountered from--ground surface to approximately-3 feet bgs. Underlying the silty sand is poorly --graded-sand-with-silt to-approximate-ly-9-feet-bgs, followedbywell-graded sand to the total depth of the borings (21 feet bgs). A layer of clay was encountered from approximately 16 to 19 feet bgs in well boring MW-15. In well boring MW-14, silty sand was observed from ground surface to approximately 9 feet bgs,underlain by silty sand to approximately 18 feet bgs,then by well-graded - sand to 21. feet bgs (total depth). I Welt MW-17 was installed in the asphalt along the east side of Harlan Road (Figure 2). Soil encounter during the drilling of well boring 1\4W-17 consisted of poorly graded sand from 0.5 to 6 e 140193.12-2 6