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ATTACHMENT A <br /> FIELD AND LABORATORY PROCEDURES <br /> Exploratory Drilling <br /> The soil boring was drilled using an 8-inch hollow-stem auger Boring B-7 was terminated <br /> once two consecutive "clean" samples (based on field observations and measurements) were <br /> collected, refusal occurs, or groundwater encountered Boring B-7 was logged by a Pacific <br /> Environmental Group, Inc geologist using the Unified Soil Classification System and <br /> standard geologic techniques Soil samples logged were collected at 5-foot depth intervals <br /> using a California-modified split-spoon sampler The sampler was driven to a maximum of <br /> 18 inches using a 140-pound hammer with a 30-inch drop All soil samples for chemical <br /> analysis were retained in brass liners, capped with Teflon squares and plastic end caps, and <br /> sealed in clean zip-lock bags The samples were placed on ice for transport to the laboratory <br /> accompanied by chain-of-custody documentation All down-hole drilling and sampling <br /> equipment was steam-cleaned following the completion of the soil boring Down-hole <br /> sampling equipment was washed in a tri-sodium phosphate or alconox solution between <br /> samples <br /> Organic Vapor Procedures <br /> Soil samples collected at 5-foot depth intervals during drilling were analyzed in the field for <br /> ionizable organic compounds using a photo-ionization detector(FID) with a 10 2 eV lamp <br /> The test procedure involved measuring approximately 30 grams from an undisturbed soil <br /> sample, placing this subsample in a clean clear ziplock plastic quart bag, and sealing the bag <br /> The bag was warmed for approximately 20 minutes (in the sun), then the bag was opened <br /> slightly to allow the testing probe device to enter into the head-space within the bag to be <br /> tested for total organic vapor, measured in parts per million as benzene (ppm, <br /> volume/volume) The instrument was calibrated prior to drilling using a 100-ppm <br /> isobutylene standard (in air) and a sensitivity factor of 55 which relates the ionization <br /> potential of benzene to that of isobutylene at 100 ppm The results of the field testing were <br /> noted on the boring logs PID readings were useful for indicating relative levels of <br /> contamination, but were not used to evaluate hydrocarbon levels with the confidence of <br /> laboratory analyses <br /> 920039 1B/SGWRPRT A-1 September 4 1997 <br />