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Work plan fordditiona/Groundwater Assessment <br /> Former Chevron Service Station 94054 <br /> March 19, 2010 <br /> 3.5 SOIL BORINGS <br /> Prior to drilling, the_two borings will be hand cleared using an air knife or hand auger to a <br /> minimum depth of'8 feet 1 inch (utility clearance depth) bgs. The two offsite borings will be <br /> advanced using hollow stem augers (HSA) to approximately 50 feet bgs. The completion depth <br /> and well screen interval will be based on conditions encountered in the field. <br /> 3.5.1 Soil Sampling and Screening <br /> Soil samples for logging purposes will be collected continuously for visual classification from 8 <br /> feet 1 inch bgs to the total borehole depth using_a California-modified split-spoon sampler, core <br /> barrel sampler, or similar sampling device. Soil samples will be field screened with a <br /> photo-ionization detector (PID). The soil screening procedures will involve measuring <br /> approximately 30 grams from a relatively undisturbed soil sample and placing this sample in a <br /> sealed container (zip-lock bag). The bag will be warmed in the sun for approximately 20 <br /> minutes, then the head space within the bag will be tested for total organic vapor, measured in <br /> parts per million (ppm). The PID results will be recorded on the field boring logs. Although PID <br /> measurements are useful for indicating relative levels of impact, the measurements cannot be <br /> used to evaluate hydrocarbon levels with the confidence of laboratory results. <br /> Up to 10 soil samples will be collected from each of the B zone borings at approximate five foot <br /> intervals and will be submitted to a laboratory for analysis based on PID measurements and/or <br /> visual characteristics (i,e. staining, odors, sheen). The select soil samples, and applicable <br /> duplicate samples, will be retained in brass, stainless steel, or plastic liners, capped with Teflon <br /> squares and plastic end caps, and sealed in zip-lock bags. The samples will be placed on ice, <br /> cooled to approximately 4 degrees centigrade (°C), and transported to a State of California <br /> certified laboratory under chain-of-custody documentation. The soil samples will be analyzed for <br /> the following constituents: <br /> • TPH-GRO [C6-C12] by United States Environmental Protection Agency (USEPA) <br /> Method 8015 <br /> • MTBE, BTEX, tertiary butyl alcohol (TBA), tertiary amyl methyl ether(TAME), <br /> 1,2-dichloroethane (1,2-DCA), and ethyl dibromide (1,2-dibromoethane) (EDB) by <br /> USEPA Method 8260B <br /> All down-hole drilling and sampling equipment will be steam-cleaned following the completion of <br /> each soil boring. Down-hole equipment will be washed in a tri-sodium phosphate or Alconoxo <br /> solution between samples. <br /> \\CA5FP\Data\Aprojecct\ENV.CHEVRON\94054\6 Deliverables\Work Plans\2010\TemplWork Plan for Site Assessment_4821010950.dor 4 <br />