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Site Assessment Proposal <br /> Frontier Transportation <br /> Doc # 101501 <br /> October 15, 1997 <br /> Groundwater samples were collected from MW- 1 , MW-2, and MW-3 on August 30, 1996 <br /> by Twinning. Results are presented in Table 3 . <br /> TABLE 3: 1996 Groundwater Analysis Results u /I <br /> Well ID Date DTW TPH-g TPH-d B T E X MTBE <br /> MW- 1 08/96 10.34' 1 ,800 <50 98 18. 8 55 . 8 130 11300 <br /> 04/97 9.21 ' 520 68 31 ND 2.8 1 . 5 910 <br /> MW-2 08/96 10.20' 850 95 12.7 7 . 9 4. 5 120 12.3 <br /> 04/97 9.02' 73 250 6.4 ND 2. 2 0.7 ND <br /> MW-3 08/96 10.40' 81000 610 610 170 96.6 540 1 ,700 <br /> 04/97 1 9.25' 1 305000 1 1 ,800 1 32200 1 21000 1 11400 13000 1400 <br /> 1Based on the site assessment results, petroleum hydrocarbons have impacted the capillary <br /> fringe and subsurface water between 9 . 5' and 11 ' bg in the area bound by borings B-2, B-3 , B-4, <br /> MW- 1RA, MW- IRB, MW-2RA, and MW-3 . This coincides with maximum dissolved gasoline <br /> concentrations identified in the shallow subsurface water at MW-3 . <br /> 3.0) SITE GEOLOGY/HYDROGEOLOGY <br /> The site is located on the boundary of the Sacramento Valley and the San Joaquin Valley <br /> within the west-central portion of the Great Valley Geomorphic province of California. The <br /> Great Valley has been filled with a sequence of older to younger alluvium of Pliocene to Holocene <br /> age which overlay sedimentary rocks of Cretaceous to Tertiary age. These sedimentary units, in <br /> turn, overlay a crystalline basement of Paleozoic and Mesozoic metamorphic and igneous rocks. <br /> The shallow subsurface geology in the site vicinity is a heterogeneous mix of gravel, sand, silt, and <br /> clay (Reference; Site Characterization Report, Twining Laboratories, October 16, 1996). <br /> First subsurface water was encountered at depths from 11 ' to 12' bg during tank removal <br /> and monitoring well installation at this site in 1995 and 1996 . Elevation and flow of first <br /> encountered water was described as influenced by pumping of water wells and recharge from <br /> various sources causing gradient fluctuation. The flow direction for this subsurface water was <br /> identified as northwesterly with a shallow gradient of 0. 002 feet per foot (Reference; Site <br /> Characterization Report. Twining Laboratories, October 16, 1996), <br /> 4. 0) DATA ANALYSIS <br /> Soil boring sample results identified low to non-detectable concentrations of petroleum <br /> 3 <br /> I <br />