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Biagini Properties, Inc. D06105.01 <br /> April 11, 2000 Page 2 <br /> • Install passive soil vapor screening modules at the predetermined locations and allow the <br /> modules to remain in place for at least two weeks; <br /> • Retrieve the passive soil vapor screening modules; <br /> • Submit the passive soil vapor screening modules to W. L. Gore and Associates, Inc. for <br /> laboratory analysis; and <br /> • Prepare a technical report detailing the results of the passive soil vapor survey and <br /> addressing whether additional assessment is necessary. <br /> Copies of the required SJCEHD Well Permit Application Forms are contained in Appendix C. <br /> 3.0 BACKGROUND <br /> A description of the site, the geologic and hydrologic characteristics, and the project history are <br /> summarized in the following subsections. <br /> 3.1 Site Description: The project site is at 3422 Suite K, West Hammer Lane, Stockton, <br /> Stockton County, California. The site is in the southeast quarter of Section 18, Township 2 <br /> North, Range 6 East, Mount Diablo Baseline and Meridian. The site elevation is approximately <br /> 3 feet above mean sea level. Drawing 1 is a site location map. <br /> 3.2 Geology: The site is in the northern portion of the San Joaquin Valley within the Central <br /> portion of the Great Valley geomorphic province of California. The Great Valley is a nearly flat <br /> northwest- to southeast-trending structural basin approximately 450 miles long by 50 miles wide. <br /> The Great Valley has been filled with a sequence of older to younger alluvium of Pliocene to <br /> Holocene age which overlie sedimentary rocks of Cretaceous to Tertiary age. These sedimentary <br /> units, in turn, overlie a crystalline basement of Paleozoic and Mesozoic metamorphic and <br /> igneous rocks. The shallow subsurface geology in the site vicinity is a heterogeneous mix of <br /> gravel, sand, silt, and clay (Hackel, 1966). <br /> 3.3 Hydrology: First-encountered groundwater in the site vicinity occurs under unconfined <br /> groundwater conditions. Sediments containing fresh groundwater in the Stockton area are <br /> largely unconsolidated silts and sands which were derived from river channel, flood plain, and <br /> alluvial fan deposits of Pliocene to Recent age (Davis, et al., 1959). Based on the San Joaquin <br /> County Flood Control and Water Conversation District map of lines of equal elevation of <br /> groundwater, Fall 1998, depth to first encountered groundwater was approximately 9 feet below <br /> site grade (BSG). The estimated regional groundwater flow direction at that time was toward the <br /> southwest. <br /> 3.4 Project History: Based on a Phase I investigation report prepared by Paragon <br /> Environmental Services, Inc. dated October 14, 1999, a dry cleaner facility operated dry cleaning <br /> equipment from approximately 1989 to approximately 1994. The facility has since 1994 <br />