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7ksdwe11&Ro110 <br /> ' 3.5 Area 4 <br /> 3.5.1 Soil and Grab Groundwater Sampling <br /> On 15 September 1999, Precision used the backhoe to dig exploratory pits at the locations shown <br /> on Figure 7. Test pits 4TP-1 through 4TP-3 were excavated to a depth of approximately 10 feet. <br /> Soil samples were collected at the depths shown on the test pit logs in Appendix C. <br /> On 17 September 1999, Precision used the SD-1 direct push rig to collect soil and groundwater <br /> samples. Soil boring 413-1 was pushed to a depth of 32 feet. Soil samples were collected at the <br /> depths shown on the boring logs in Appendix C and the locations shown on Figure 7. <br /> 4.0 PRELIMINARY ENDANGERMENT ASSESSMENTS <br /> PreliminaryEndangerment Assessments were performed for each of the south shore parcels in <br /> ' order to help quantify the human health risks associated with hazardous materials in the soil and <br /> groundwater. The PEAS were prepared in accordance with the Preliminary Endangerment <br /> ' Assessment(PEA) Guidance Manual which was prepared by the California Environmental <br /> Protection Agency (Cal/EPA) in 1994 and updated in 1996. The approach to conducting the risk <br /> screening evaluation consists of a compilation of methods, models, and assumptions typically <br /> used by the U.S. Environmental Protection Agency (U.S. EPA)to quantify non-carcinogenic <br /> hazards and carcinogenic risks. <br /> The PEAs were conducted by SOMA Corporation in association with Treadwell & Rollo. A <br /> copy of SOMA's PEA report is included as Appendix D, and the PEA findings are summarized <br /> 1 in the Section 5.0. <br /> r5.0 FINDINGS AND CONCLUSIONS <br /> ' The work performed during the study of the Stockton South Shore parcels confirms that soil and <br /> groundwater contamination, generally in the form of petroleum fuel hydrocarbons, is present at <br /> ' 12 <br /> 21171119.DGD 13 December 1999 <br />