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PRIVILEGED & CONFIDENTIAL <br /> c. Advanced one soil boring to a maximum depth of 55 feet bgs and converted the boring <br />' into groundwater monitoring well MW-4; <br /> d. Collected soil samples at five-foot bgs intervals, and submitted selected samples for <br /> analysis of TPH and BTEX in accordance with EPA Methods 8015M (Simulated <br /> Distillation), and 8020, respectively; <br /> e, Surveyed the elevation and Iocation of monitoring well MW-4; <br /> f. Collected one groundwater sample from each monitoring well along with a blind <br /> duplicate, and submitted the samples for analyses of TPH and BTEX/MTBE in <br />' accordance with EPA Methods 8015M (Simulated Distillation), and EPA Method 8020 <br /> for BTEX/MTBE; and <br /> g. Conducted the following quality control procedures: <br />' + One trip-blank was supplied by and returned to the laboratory; <br /> • One duplicate grab-groundwater sample was collected and submitted for analyses <br /> using EPA Methods 8015M, and 8015M18020; and <br />' h. Backfilled and repaved the drilled area with a concrete finish <br />! GEOLOGY AND HYDROGEOLOGY <br /> Stockton is located in the western portion of the Great Valley geomorphic province of <br /> California. The valley is a nearly flat lying, elongate trough trending northwest and <br /> southeast for approximately 450 miles. The valley is bordered by the igneous Sierra <br /> Nevada to the east and the sedimentary and metamorphic Coast Ranges to the west. The <br />' surficial and upper several hundred feet of subsurface sedimentary layers consist of a great <br /> thickness of predominantly unconsolidated alluvial and flooplain deposits (dominantly <br /> sand, silt and clay), Quaternary in age, which were derived from the predominantly granitic <br />' mountains of the Sierra Nevada. Beneath the upper sedimentary deposits lies a thick <br /> sequence of marine deposits of Mesozoic age. These units are further underlain by a pre- <br /> Jurassic complex of igneous and metamorphic basement rock.' <br /> In the vicinity of the subject property, depth to groundwater is approximately 60 feet bgs <br /> with a flow direction to the northeast. <br /> SOIL AND GROUNDWATER INVESTIGATION <br /> Monitoring Well Permits <br /> Building Analytics applied to the SJCEHD for a well permit prior to advancing the borings <br /> and installing the monitoring wells. The well permit was approved on August 5, 1997. A <br /> copy of the permit is included in Appendix A. <br /> Advanced GeoEnvironmental, Inc., Corrective Action Plan, March 1995. <br /> 3 197501-Stockton <br />