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ARUMI5 BBL Ms. Victoria McCartney <br /> July 12, 2007 <br /> First Encountered Groundwater Monitoring Wells <br /> Four shallow borings will be advanced using 8-inch diameter hollow stem augers to <br /> approximately 27 feet bgs. Upon completion a 2-inch diameter groundwater <br /> monitoring well will be installed. It is anticipated that the groundwater monitoring well <br /> will be screened from approximately 17 to 27 feet bgs.The actual screen and depth <br /> interval will be determined based on observations in the Feld.A generalized first <br /> encountered groundwater monitoring well construction detail is included as Figure 2. <br /> Deep Groundwater Monitoring Wells <br /> In order to minimize the potential for cross-contamination between the shallow and <br /> deep zones, each of the four deep boreholes will be double-cased with conductor <br /> casing to approximately 45 feet bgs. The conductor casing will be advanced using <br /> 15.5-inch diameter hollow stem augers. <br /> Once the conductor casing is set, a borehole will be advanced through the conductor <br /> casing to approximately 60 feet bgs using 8-inch hollow stem augers to allow for the <br /> installation of the deep monitoring wells. Upon completion a 2-inch diameter <br /> groundwater monitoring well will be installed. It is anticipated that the groundwater <br /> monitoring well will be screened from approximately 50 to 60 feet bgs.The actual <br /> screen depth and interval will be determined based on observations in the field.A <br /> generalized deep monitoring well construction detail is included as Figure 3. <br /> Soil Sampling and Screening <br /> Soil samples for logging purposes will be collected continuously for visual <br /> classification from 8-feet 1-inch bgs to the total borehole depth using either a <br /> California-modified split-spoon sampler, Simul-Probe or Enviro-Core sampler. <br /> Soil samples will be Feld screened with a photo-ionization detector(PID).The soil <br /> screening procedures will involve measuring approximately 30 grams from a <br /> relatively undisturbed soil sample, placing this sample in a sealed container(zip-lock <br /> bag). The bag will be warmed in the sun for approximately 20 minutes, then the head <br /> space within the bag will be tested for total organic vapor, measured in parts per <br /> million(ppm: volume/volume). The PID results will be noted on the field boring logs. <br /> PID readings are useful for indicating relative levels of contamination, but can't be <br /> used to evaluate hydrocarbon levels with the confidence of laboratory results. Soil <br /> samples will not be collected for laboratory analysis during the advancement of the <br /> borings. <br /> Page: <br /> 3/5 <br />