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i CNIO&A17-CA us lac. Page 5 Valley wholesale Drug Company Project No 989 2 (�� November 8,2004 T� ' • 04GP-6 indicated the presence of trace levels of MtBE (2 9 µg/L) 04GP-6 was non- detect above laboratory reporting limits for all other analyzed constituents • 04GP-8 indicated the presence of trace levels of MtBE (0 58 µg/L) 04GP-8 was non- detect above laboratory reporting limits for all other analyzed constituents • 04GP-3, 04GP-4, 04GP-5 and 04GP-7 were non-detect above laboratory reporting lirmts ' for all analyzed constituents • MtBE levels detected during this event were below the health advisory limits and below ' the taste and odor threshold A summary of groundwater analytical data from the GeoProbe investigation is included as ' Table 2 in Appendix A 2.5 Hydrogeologic System ' 2.5.1 Regional Structure Valley Wholesale Drug Company (VWDC) is located in the southwest quarter of the of ' Section 7, TIN, R6E, related to the Mount Diablo B&M, on the United States Geological Survey (USGS) topographic map, Stockton West Quadrangle, California, 7 5 minutes series A review of the USGS Topographic Map reveals that the elevation of this site is approximately 10-feet above mean sea level (AMSL) The site is located on the gradually sloped floor of the northern San Joaquin Valley The ' geologic composition of the area is characterized as fluvial deposits of the San Joaquin - Sacramento River delta system that overlay continental rocks and deposits derived from erosion of the Sierra Nevada Mountain Range located approximately 50 miles northeast of ' Modesto ' The southwest tilting Sierra Nevada fault block underlies the northern San Joaquin Valley area Overlying the consolidated rocks are unconsolidated sediments The lower consolidated batholithic and metamorphic rocks are poorly transmissive, however the ' overlying sedimentary layers are often quite permeable These unconsolidated layers include Pliocene/Pleistocene age continental deposits, Pleistocene age lacustrine and marsh deposits, and Holocene older and younger alluviums and flood-basin deposits ' 2.5.2 Regional Stratigraphy The USDA Soil Survey of San Joaquin County, California (October 1992), states the area ' beneath the VWDC is categorized as being urban land with the following description o The urban land unit consists of closely built-up areas in cities Streets, parking lots, buildings, and other structures cover more than 85 percent of the surface The ' landscape has been so altered by urban works that identification of the soils is not feasible This unit is not assigned a capability classification or a vegetative soil group