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19 September 1995 <br /> AGE-NC Project No. 95-0183 <br /> Page 2 of 4 <br /> approximately 450 miles. The valley is enclosed by the igneous Sierra Nevada to the east and the <br /> sedimentary and metamorphic Coast Ranges to the west. The surficial and upper several hundred feet <br /> of subsurface layers consists of a great thickness of predominantly unconsolidated alluvial and <br /> floodplain deposits(dominantly sands, silts, and clays) of Quaternary age, which are derived from the <br /> predominantly granitic mountains of the Sierra Nevada. Beneath the upper sedimentary deposits lie <br /> a thick 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 /> 2.3. GROUND WATER DEPTH <br /> The water-table surface beneath.the site occurs at a depth of approximately 85 feet below site grade <br /> (BSG). The uppermost ground water flows in an unconfined aquifer. With depth, the aquifer <br /> becomes more confined due to the presence of mixed heterogeneous layers of sediments. The <br /> regional direction of ground water flow in the upper aquifer is generally toward the northeast. <br /> 3.0. SCOPE OF WORK <br /> The scope of work for the proposed investigation includes advancing five soil borings to a maximum <br /> depth of 25 feet. Borings will be advanced using a Geoprobe 5400, utilizing direct push technology. <br /> Soil will be continuously cored and selected soil samples will be preserved. Upon completion of the <br /> investigation, a report of the findings will be prepared and will include recommendations for further <br /> investigation, if necessary. Drilling for this investigation is to be performed by Advanced <br /> GeoEnvironmental Inc. Laboratory analyses will be performed by McCampbell Analytical, Inc., a <br /> State-certified laboratory located in Pacheco, California. <br /> 3.1. EQUIPMENT DECONTAMINATION <br /> All sampling tools and brass sleeves used for sample collection will be thoroughly rinsed with clean <br /> water after washing with a solution of Alconox. All probe rods are cleaned prior to advancement in <br /> each borehole. <br /> 3.2. LABORATORY ANALYSIS <br /> Selected soil samples will be analyzed for the following constituents: total petroleum hydrocarbons <br /> quantified as gasoline(TPH-g);benzene, toluene, ethylbenzene, and xylenes (BTEJQ; and total lead. <br /> A minimum of one soil sample will be analyzed from each probing. Laboratory reports of soil <br /> analyses, testing methods, laboratory quality assurance/quality control (QA/QC) reports, and soil <br />