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1y.... ....... 0, <br /> r' <br /> poorly sorted clay, silt, sand, and gravel and in places some <br /> Thebedsof maximumystone# sitthicknesslrepo tedainstheop o and formatioconnsmarete. <br /> 3,000 feet. <br /> Continental deposits of Quaternary age crop out primarily <br /> along the major rivers and streams of the ;Talley as well as <br /> other low-lying areas; the deposits include rivar deposits, <br /> flood-basin deposits, and sand dunes. River deposits, <br /> W including channel and flood-plain deposits, are considered to <br /> be the most permeable deposits in the valley; however, they <br /> are generally not tapped by wells. Flood-basin deposits <br /> consist largely of fine-grained beds that restrict the <br /> ,vertical movement of water. <br /> 3.0 FIELD METHODS AND PROCEDURES <br /> To assess the nature and extent of subsurface contamination <br /> and the duality of the shallow ground water at the site, <br /> Alton Geoscience, Xnc. installed four additional soil borings <br /> offsite which were converted to monitoring wells. During <br /> drilling soil and groundwater samples were collected for <br /> laboratory analysis. The procedures and methods used during <br /> field activities were in accordance with the requirements of <br /> the City of Tracy, the SJCEHS, and the RWQCB. <br /> 3.1 u..,i anrincs__and—`^amnlina <br /> Prior to commencement of drilling activities, permits for the <br /> Proposed borings and grour_d water monitoring wells were <br /> obtained from the SJCEHS. Encroacizment permits were obtained <br /> from the City of Tracy Engineering Department for all soil <br /> borings to be installed offsite within the public right-of- <br /> . <br /> ight-of- <br /> its are presented in Appendix B. <br /> way. Copies of the perm <br /> on April 23, 1990 and August 8, 1990, Alton Geoscience <br /> of four soil borings. All four of <br /> supervised the drilling <br /> these borings were subsequently converted to ground water <br /> monitoring wells. The drilling activities were performed by <br /> West Hazmat Drilling Corporation of Rancho Cordova, with <br /> California, using a truck mounted CME 75 drilling rig <br /> hollow-stem augers. <br /> Soil Borings p-1 and P-2 were drilled to a total depth of <br /> 20 feet using an 8-inch-diameter, hollow-stem auger, while <br /> Soil Borings B-1 and B-2 were drilled to a total depth of <br /> 15 feet. Because of the sh- Jow ground water table, only one <br /> soil sample was collected from each boring at 5 feet below <br /> grace using a modified California split--spoon sampler lined <br /> with clean brass tubes. The soil sample tubes were sealed <br /> 5 <br />