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n DeBocr Truck Lines, Inc. l 201 West Sth Street, Ripon, California Phase I Report of Findings September 9, 1994Page. S 4.0 Soil Conditions The borings penetrated units of silt and sand. The upper unit, to 7 feet, is a micaceous sandy silt (ML) in MW-1 & 2,but grades to a micaceous silty sand(SM) in MW-3. I -� The underlying unit, to the total boring depth of 40 feet, is a poorly graded micaceous sand (SP) in MW-2 & 3, but grades to a well-sorted sand (SW) in MW-1 from 6 to 18 feet. Within this sand unit is a two foot silty sand (SM) at 12 and 14 feet in MW-2 & 3; respectively (Figures 3 & 4). There is also a silt (MH} unit of two and one-half feet iri' MW-2 and two feet in MW-3 at 25.5 and 26 feet, respectively. Both of these beds (SM&I MH) do not appear in MW-1 and may account for the migration of contaminants to 15" feet in MW-1 as shown on Figure 5. ii Soil samples from each boring, at 15, 20 and 25 feet, were sent for laboratory analysis.;; MW-1 had only Xylene contamination of 19k the 15 foot sample.!�� g �in p Iv1tiV-2 only had„ Toluene and Xylene contamination, at 15 feet, of 5.0 pg/kg and 5.2 µg/kg, respectively. NM-3 had no detectable contaminants (Figures 5 & 6, Table 1, Appendix A). . S.0 Groundwater Conditions j Water samples taken 7/27/94 from the three developed monitoring wells all tested "ND",:;; y, non-detect (Table 2, Appendix B). Water level readings taken 7/27/94 and surveyed well collar elevations were: used to lI calculate the groundwater elevation at each monitoring wdl (Table 3, A endix,F . The '! Fp } groundwater gradient was calculated at 0.003 ft/ft, dipping N 41 E (Figure 8). 6.0 Geology Ripon lies in the Central Valley Physiographic Province of California. The Valley is about '! 40 miles wide in this area. It is bounded to the west by the foothills of the Coast Ranges, and to the east by the foothills of the Sierra Nevada Range. The Ripon area is nearly devoid of structural geologic features. The Valley is floored by unconsolidated Quaternary sediments to depths of at least 400 or jl more feet in the Ripon area. All of these units can be considered soils in the engineering sense, because they are unconsolidated. Quaternary sediments in the Central Valley were deposited as a series of coalescing alluvial fans. The fans originated where valleys of the major streams which drained the Sierra Nevada Range emptied .into the broad expanses of .I ;i � r r