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Aquifer Pump Test Report of Findings Frontier Transportation, Inc. November 8, 2006 Page 3 maximum TPH-gas detected was 1 . 7 mg/kg at 10 ' bgs in MW- 15 using EPA Method 8015M. No detectable BTEX was identified in the soil column for MW- 15 through MW48 . See Figure 2 for well locations. In August 2005, BEA installed three shallow groundwater wells. Monitoring wells MW- 19, MW-20 and MW-21 were advanced to 20' bgs and screened from 5 ' bgs to 20 ' bgs. Then, in September 2006, two additional wells were installed in preparation for an aquifer pump test at MW- 3R. MW-22 and MW-23 were placed approximately 10 .5 ' and 21 .5 ' north of MW-3R, respectively. See Figure 2 for well locations. Quarterly groundwater monitoring has continued at the site and has identified the migration of MTBE to the west. Levels of dissolved MTBE have been consistently high (above MCL of 14 ug/L) in MW- I and MW-3R. Elevated levels of MTBE first appeared in MW-9 in March 2005 and have continued to be present. 3 .0) SITE GEOLOGY41YDROGEOLOGY 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 age which overlay sedimentary rocks of Cretaceous to Tertiary age. These sedimentary units, in tum, 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 Report, Twining Laboratories, October 16, 1996) . BEII encountered predominantly heterogeneous clays from 0' to 30' bgs and fine-grained sands from 30 ' to 40 ' bgs during well advancement of MW- 15 through MW- 18 . First subsurface water was encountered at depths from I F to 12' bgs during tank removal and monitoring well installation at this site in 1995 and 1996 . Since then, shallow subsurface water has been encountered beneath the site between 6' and 10' bgs. Shallow wells MW- 19, MW-20 and MW- 21 encountered groundwater at approximately 9 .5 ' to 14' bgs during boring advancement. Groundwater was identified in MW-22 and MW-23 at 14' to 14. 5 ' bgs during well advancement drilling. See Appendix A for recent boring logs.