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tSunland Gasoline March 14, 2000 <br /> 2085 Fremont Street, Stockton, California Page 7 <br /> ' Report of Findings, Site Characterization <br /> climatic changes in the Sierras. This has resulted in a predominance of fine-grained silts <br /> ' and clays in the subsurface of the area. <br /> S.1 Local Geology <br /> 1 The geology underlying the subject site consists of alternating layers of silt and sand to <br /> an approximate depth of fifty feet (50'). A clay layer is present at approximately 55- <br /> 60' b.g.l. Beneath this clay layer alternating layers of sand, silt and clay are present to a <br /> depth of eighty feet(80'). The boring logs can be found in Appendix B. <br /> 1 <br /> 6.0 Hydrology <br /> ' California and Federal Governments have mandated that virtually all groundwater is <br /> beneficial for current or future use, unless it can be demonstrated that no beneficial use is <br /> ' known. <br /> This "aquifer" is considered to be of beneficial use and as a result, must be protected from <br /> ' contamination. Those identified uses include agricultural and industrial, as well as <br /> potential use for animal or human consumption. <br /> ' 6.1 Local Hydrology <br /> Groundwater was encountered at approximately fifty-eight feet (58') below <br /> ' ground level. The groundwater in the boring rose to forty-seven feet (47') by the <br /> time the groundwater sample was collected. <br /> 1 <br /> 7 0 Conclusions <br /> 1 Based on the results presented in this report, NNW believes that the soil and groundwater <br /> underlying this site has been significantly impacted by petroleum hydrocarbons. The <br /> source of soil contamination seems to be in the vicinity of the former underground storage <br /> tanks. This is concluded based on the following observations: <br /> ' • Boring B-1 was completed in the vicinity of the former UST's. <br /> The results from boring B-1 indicate high levels of petroleum hydrocarbons at a depth <br /> ' beginning at fifteen feet (15')below ground level. <br /> Groundwater was encountered at a depth of approximately fifty-eight feet (58'). <br /> ' Therefore, groundwater migration of contaminates at depths significantly above the <br />