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ALTON GEOSCIENCE <br /> GENERAL FIELD PROCEDURES <br /> FOR <br /> SOIL BOREHOLE DRILLING AND SAMPLING <br /> WELL CONSTRUCTION DETAILS <br /> Exploratory borings will bc: drilled using an 8-inch-diameter, <br /> continuous-flight, hallow-stem auger. To avoid cross- <br /> contamination, the augers will be steam cleaned prior to <br /> drilling each borehole. The soil borings will be located <br /> offsite to assess the extent of potential petroleum <br /> hydrocarbons in the soil and ground water, if any. <br /> So . <br /> During drilling, samples will be collected at 5terminating at <br /> intervals, beginning at 5 feet below g and <br /> least 15 feet Theto the samplesirst willsat <br /> beuretrievedeaheador 1of thelead <br /> clay layer. b 2•-inch-diameter split-spoon <br /> auger using an 18-inch-long y <br /> sampler lined with steam clean brass tubes. Theound hsampler will <br /> Blow <br /> be driven by a 30-inch free fall of a successive <br /> p <br /> counts will be recorded at three <br /> Before each sampling event, esampler and sample tubesvalsare. <br /> washed using a trisodium phosphate and water solution, one <br /> two tap water rinses. <br /> iately <br /> Upon retrieval, the middle sample elytubsealed will bwith aluminium <br /> removed from the sampler and securely <br /> foil and polyurethane caps and wrapped with clear tape. The <br /> sample will be labeled with the identification, <br /> sample depth, <br /> initials, and date of collection. The soi <br /> sampler's l sample <br /> will <br /> sampler's <br /> kept on dry or blue ice prior to and during transport <br /> to a California-certified laboratory- <br /> one sample from each sampling interval will be retained for <br /> laboratory analysis and analyzed for the substances <br /> athat <br /> have <br /> l as <br /> been historically stored ienpassibleedegradationkor <br /> constituents formed by primary tank contents. The samples <br /> transformation of the p er chain of custody <br /> will be transported following the prop <br /> procedures. <br /> collected periodicatsoilesamplesny <br /> Grab samples will be <br /> contacts between different formation types. <br /> will be screened for the presence of hydrocarbon volatiles <br /> using a combustible gas indicator (CGI) <br /> a staff geologist will describe the soil <br /> A staff engineer or <br /> nified Soil Classification system, and <br /> samples using the U <br /> ates of density/consistency, moisture, <br /> included field estim <br />