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Stockton 99 Speedway <br /> Preliminary Endangerment Assessment Workplan April 12,2007 <br /> 1 4.0 FIELD SAMPLING PLAN <br /> 4.1 Sampling Objectives <br /> 4.1.1 General <br /> I <br /> f Additional sampling of soil will be conducted as part of the PEA. The sampling will be designed to <br /> provide additional analytical data to supplement current data and provide new data for uncharacterized <br /> AOCs located on the Site. The data collected will be used to: <br /> • Identify source areas associated with releases of TPH and VOCs to soil; <br /> • Evaluate the lateral and vertical extent of organochlorine pesticides and metals in soil; and <br /> • Confirm previous sample results and test for metals, TPH and VOCs in soil associated with the <br /> AOCs. <br /> Figure 5 presents a map showing the proposed sampling locations. <br /> 4.1.2 Data Gap Identification <br /> As described in Section 2, insufficient information is available to assess: <br /> t <br /> • The presence and extent of organochlorine pesticides in soil underlying the Site; <br /> l; • The localized extent of TPH and organochlorine pesticides in the Debris Fill Area; and <br /> • The presence and extent of metals in soil underlying the Site. <br /> Proposed field investigation activities to address these data gaps include a soil boring program to collect <br /> soil samples. <br /> 4.1.3 Soil Samples <br /> A set of soil borings will be advanced to allow the collection of soil samples for the purpose of chemical <br /> analysis, lithologic characterization, and delineation of the extent and magnitude of contamination. <br /> Direct-push sampling techniques (DPT) will be used to collect soil samples. Initially, 39 soil borings will ` <br /> be advanced at the locations shown on Figure 5. <br /> Soil samples for lithological characterization will be collected continuously to a maximum depth ranging <br /> from 14 to 25-feet bgs. Soil samples for chemical analyses will be retained at minimum depths of 0.5, 2 <br /> t' <br /> and 54eet bgs intervals and at lithologic changes. All soil samples will be logged according to Unified <br /> Soil Classification System (USCS), including color, moisture content, mottling, and presence of staining <br /> k <br /> PSA wmkpla7.Final.doc 4-1 The Source Group,Inc. <br /> i <br />