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Permitting for one ground water monitoring well was applied for <br /> from San Joaquin County PHS/EHD and granted prior to any drilling <br /> (see Appendix B) . <br /> Well Development and Surve of MW8 <br /> MW8 was developed on February 11, 1993 by Western Geo-Engineers <br /> using surge block and pumping to attain the most turbid state of <br /> the purged water, see Appendix D. <br /> The surging was performed by raising and lowering a slightly <br /> undersized swab through the ground water interval on the well . <br /> The swab was attached to a line, raised and lowered several times <br /> through the ground water to agitate and suspend the settled <br /> sediments in the well . <br /> Lawrence Tank Testing (LTT) utilized a turbine vacuum pump to <br /> vacate the .wells of enough water to represent minimal influence <br /> to the ground water from the construction of the monitoring <br /> wells . The purged water produced by this process was placed in <br /> labeled 55 gallon drums on site. <br /> Before the ground water sampling a state certified land surveyor <br /> on February 11, 1993 surveyed in the elevation of MW8 . The well <br /> surveying was done to an accuracy of . 01 feet with reference to <br /> mean sea level as the benchmark and taken to the top of casing <br /> and rim of the traffic box of the well, see Appendix D. <br /> GEOLOGY <br /> The deposits under the site are Recent to Pleistocene age <br /> alluvium and consists of lenticular silt, sand, gravel and clay <br /> representing a heterogeneous fluvial environment . The Problem <br /> Assessment Report for this site (Appendix A of the Quarterly <br /> Monitoring Report for September 24 , 1991) details the local and <br /> regional geology and hydrogeology. The soil samples and drill <br /> cuttings of MW8 indicated similar lithologies as that presented <br /> in the Problem Assessment Report . <br /> As in many alluvial fan environments, variable soil types were <br /> encountered while drilling MW8 (Appendix C, Limited Drilling <br /> Report-Borehole Logs) . Two soil types were found in the monitor <br /> well drilled: A grey green to medium brown silty clay which is <br /> interbedded with various thicknesses and textured sand lenses, <br /> which caps the site from the surface to approximately 55 BGS and <br /> a well sorted, fine grained sand grading to a poorly sorted, <br /> medium to coarse grained sand from 55' to 581 . The well was <br /> terminated at 60' , 2 ' into a possible clay aquitard from 58' to <br /> 601 . <br /> 3 <br /> e <br />