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U Unocal Service Station #6981 November 28, 1994 Product Dispenser Island Sampling On July 22, 1994, a GSI geologist collected three soil samples (UT-1, UT-2, and UT-3) from the vicinity of the former product dispenser islands as requested by Ms Mary Meays of the SJCEHD These samples were collected to assess the lateral extent of residual hydrocarbons in soil adjacent to the dispenser islands Ms Meays was present to observe collection of the soil samples Soil sample collection began by excavating the sample area j with a backhoe to between approximately 2 5 to 3 feet below ground surface (bgs) A hand-driven soil sampling device was used to collect undisturbed soil from the bottoms of the excavations Soil samples were collected as described in Appendix A, and delivered to Sequoia Analytical, a State-certified analytical laboratory (FLAP #1624) located in Sacramento, California Soil sample locations are shown on the Soil Sampling Plan (Figure 3), and sample depths have been summarized in Table I Stockpile Sampling GSI returned to the subject site on August 2, 1994, to collect samples of soil generated during trenching for the VES piping, product piping, and electrical lines Approximately 126 yd' of soil had been excavated and stockpiled on plastic sheeting Eight samples of • the stockpiled soil were collected at arbitrary locations within the stockpile for disposal characterization Stockpile sample collection procedures are presented in Appendix A The samples were then submitted to Sequoia Analytical for analysis as two composite samples (S-0802-la,b,c,d, and S-0802-2a,b,c,d, hereafter referred to S-0802-1 and S-0802- 2, respectively) GSI also collected four samples of soil stored in drums at the site The drummed soil was generated during the drilling and installation of vapor extraction wells VW-5 and VW-6 by RESNA The four samples were submitted to Sequoia Analytical for analysis as one composite sample (SC-0802-3a,b,c,d, hereafter referred to as SC-0802-3) VES Construction and Source Test The VES consists of six vapor wells (VW-1 through VW-6), a moisture knockout and a Baker Furnace thermal oxidizer unit As shown in the VES System Layout Diagram (Figure 4), piping from each well carries the influent vapor streams to manifold within the compound to form a single influent vapor stream As shown on the Process Flow Diagram (Figure 5), the influent vapor stream then passes through a moisture knockout drum, and then into the Baker Furnace thermal oxidizer After destruction of the extracted petroleum hydrocarbons, the vapor stream is discharged to the atmosphere under San Joaquin Valley 4955701-1 3 GeoStrategies Inc.