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0 <br /> Kennedy Jenks Consultants <br /> Section 4: Previous Soil Investigations <br /> This section summarizes the several investigations and data used to generate an initial <br /> understanding of the soil conditions around the 1-MG pond. <br /> 4.1 General Soil Survey Information <br /> According to the U.S. Department of Agriculture, Soil Conservation Service, "Soil Survey of San <br /> Joaquin County, California" dated October 1992, soils around the 1-MG pond are mapped as <br /> the Calla-Carbona complex, 8-30% slopes (USDA 1992). The surface soils of this complex are <br /> classified as well-drained clay loam, with moderately high saturated hydraulic conductivity, and <br /> high available water capacity. <br /> 4.2 Soil Borings - March 2001 <br /> Kleinfelder prepared a work plan (dated 29 December 2000) in response to CAO No. 5-00-717. <br /> Exploratory soil borings proposed in the work plan were intended to evaluate subsurface <br /> conditions at the existing 1-MG pond, the (then) proposed 84-MG storage reservoir, and the <br /> land application fields. <br /> In March 2001, two soil borings were advanced onsite: one near the 1-MG holding pond <br /> (boring TW-1) and another boring near the (then) proposed reservoir(boring TW-2) to assess <br /> impacts to soil and groundwater (Figure 3). Because boring TW-1 was a deep boring and soil <br /> samples were collected below the shallow zone (at depths of 60 and 120 feet below ground <br /> surface (bgs)) the only information relevant to the planned shallow soil investigation is that the <br /> first 33.5 feet of soil encountered at TW-1 was logged as silty sand. Details of the borings and <br /> soil samples collected can be found in Kleinfelder(2001). <br /> 4.3 Stratigraphic Information from Well Installation <br /> Using field data collected from onsite soil borings and groundwater wells, two-dimensional <br /> cross-sections have been developed in the past to illustrate the complexity of the hydrogeology <br /> of the Site. Figure 3 shows the cross-sections that were developed for previous reports, such as <br /> the Amended Report of Waste Discharge (Kennedy/Jenks 2007) and the Groundwater <br /> Characterization Report(Kennedy/Jenks 2004). Cross section D-D' in these previous reports <br /> illustrates the subsurface stratigraphy between monitoring wells MW-4 and MW-5, which can be <br /> used to infer information about the soils and stratigraphy around the 1-MG pond. Because <br /> wells MW-4 and MW-5 are also relatively close to the 1-MG pond (that is, within approximately <br /> 100 to 150 feet), the boring logs for wells MW-4 and MW5 provide a reasonable indication of <br /> the shallow soil conditions that could have been present at the 1-MG pond prior to its <br /> construction. The available information indicates that the surface soil around the pond consists <br /> of"silty sands, sand-gravel-clay mixtures"for at least the upper 70 feet of soil at well MW-4 and <br /> 15 feet of soil at well MW-5. <br /> Work Plan for Soil Characterization, Page 5 <br /> Musco Family Olive Company, Tracy, California <br /> __. ]:- gmN;brkra jorr.OA,iiNJi0M1.60_mwcuol' '.ixrxb'al aarx-1,,,"d Joc <br />