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Report of Findings ' Frontier Transportation 0200-024 March 3, 2000 Page 2 and MTBE (Methyl-tert Butyl Ether) as 1,300 mg/kg, 180.7 mg/kg, and 110 mg/kg, respectively at 10.2' bg. ' Groundwater samples were collected from monitoring wells MW-1, MW-2, and MW-3 on August 30, 1996 and April 21, 1997 by Twinning. Results are presented in Table 1. In Januaryof 1998, BEII advanced four (4) groundwater monitoring wells (MW-4 through MW-7) to assess the extent of subsurface contamination beneath the site. Soil samples were collected every five feet. Laboratory analysis of soil samples identified no detectable concentrations of TPH-g, BTEX, or MTBE. Groundwater samples were subsequently collected. IResults are tabulated in Table 1. In January 2000, BEII advanced two borings (B-5 and 13-6), installed four additional groundwater monitoring welts (MW-8 through MW-1 1), and collected nine soil vapor samples for ' a soil vapor survey as part of an additional site assessment (See Figure 2, Site Layout Map). Results are presented in Section 4 of this report 10 3.0) SITE GEOLOGY/HYDROGEOLOGY The site is located on the boundary of the Sacramento Valley and the San Joaquin Valley within the west-central portion of the Great Valley Geomorphic province of California. The Great Valley has been filled with a sequence of older to younger alluvium of Pliocene to Holocene alae which overlay sedimentary rocks of Cretaceous to Tertiary age. These sedimentary units, in turn, overlay a crystalline basement of Paleozoic and Mesozoic metamorphic and igneous rocks. The shallow subsurface geology in the site vicinity is a heterogeneous mix of gravel, sand, silt, and clay (Reference-, Site Characterization Re ort, Twining Laboratories, October 16, 1996). BEII encountered predominantly clays with traces of interbedded sands from 0' to 25' bg during well advancement in January of 2000. See Appendix A for Boring Logs. 1 First subsurface water was encountered at depths from 1 F to 12' bg during tank removal and monitoring well installation at this site in 1995 and 1996. Since then, shallow subsurface water has been encountered between 6' and 10' bg. Data collected in January of 2000 identified the flow of groundwater in a generally western direction beneath the site (See Figure 3, Groundwater Gradient Map). 4.0) SITE ASSESSMENT RESULTS On January 21, 2000, BEII advanced two borings (B-5 and B-6) near the former USTs to