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a <br /> Y^x <br /> 2.7 Disposal <br /> A composite soil sample was collected from approximately 6 yd-'of soil generated during <br /> well drilling activities. Upon analysis,the soil was determined to be non-hazardous and was <br /> disposed of at the Class Ql Zanker Road Landfiili by representatives of Erickson Incorporated <br /> on August 5, 1991. Analytical results are contained in Appendix F. <br /> i . <br /> Water generated during well development and purging remains on site at this time. <br /> r� <br /> 3.0 DiSCUSSi01T <br /> E ` 3.1 Site Geology <br /> Boring logs indicate that the shallow subsurface beneath the site is composed of clays and <br /> silts with les:-.r concentrations of sand and gravel(Appendix 13). <br /> 3.2 Site Hydrogeology <br /> During drilling of wells MW-5,MW-6 and MW 7, groundwater was encountered between 35 <br /> and 36 feet below grade. Upon equilibration groundwater was measured from 29.82 to 30.$2 <br /> feet below the well heads, at an approximate elevation of 24 fe:t below mean sea level (Tal::e <br /> !). Water table contours are depicted on Figure 3, with groundwater flowing north under an <br /> approximate hydraulic gradient of 0.005. <br /> 3.3 Soil Cxuallty Data <br /> Results of a soil gas survey conducted in 1989 revealed the presence of petroleum <br /> hydrocarbons with the greatest concentrations encountered near the former pump island <br /> locations (see Appendix v for report of soil gas survey). <br /> Analysis of the soil samples collected during the installation of wells MW-1, MW-2,MW-3 <br /> ~ and MWS, in April 1990,revealed low concentrations of petroleum hydra^n-rbons only in the <br /> sample from MW-3 (immediately downgrad"ient of the former fuel tank field). No petroleum <br /> hydrotarbl)ns were encountered in the samples from wells MW 1, MW-2 and MW (side <br /> gradient of the fuel dispensing islands,upgradient and side gradient of the former used oil <br /> tank field,respectively). These data are presented in Table ..:--- <br /> M711421-9 i(U5T/OOt4MFR 6 <br /> 3 <br />