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2.3 Topography, Geology, Hydrology <br /> The project site is situated on level terrain at the northern end of the San Joaquin Valley, part <br /> of the large northwest trending sedimentary trough termed the Central Valley of California The <br /> San Joaquin Valley contains a thick sequence of sediments which reach a depth of 10 miles in <br /> some places These sediments range in geologic age from Jurassic to Holocene and include both <br /> marine and continental deposits Near surface deposits are derived from flood and overbank <br /> river deposits consisting of irregularly interbedded and discontinuous layers of fine to coarse <br /> 1 grained unconsolidated sediments <br /> I The closest surface water to the site is the San Joaquin River, approximately one-half mile to <br /> the southwest The river in this location flows generally to the northwest and is subject to <br /> Iperiodic flooding The regional groundwater flow is generally to the northeast First <br /> groundwater beneath the site occurs at the depth of approximately 12-15 feet below grade <br /> 2.4 Proximity of Private, Municipal and Ii rigation Wells: <br /> Known well locations within a one mile radius are located on Figure 3 There are no known <br /> production wells on the project site Six groundwater monitoring wells were installed on the <br /> property as part of this investigation Also, no dry wells or septic systems exist on the site <br /> The nearest wells adjacent to the site are shallow groundwater monitoring wells used in <br /> petroleum hydrocarbon investigations at nearby properties As in the case with the Laidlaw <br /> project, these wells are screened only in the uppermost water bearing zone and, therefore, are <br /> not considered potential conduits for contaminant migration <br /> 3.0 INVESTIGATION <br /> 3.1 Phase 1 Activities <br /> �s On March 27, 1991 RESNA personnel advanced three soil borings (MW1, MW2, MW3) to <br /> approximately 30 feet below grade at the project site to accomplish the following 1) further <br /> define the lateral and vertical extent of petroleum hydrocarbon soil contamination, 2) determine <br /> soil stratigraphy, and 3) install groundwater monitoring wells within the uppermost aquifer in <br /> order to assess groundwater quality The boring/well locations are plotted in Figure 4 <br /> j <br /> I.CR492 TJL 3 <br />