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I 1 I 40 ARMIS sst First Encountered Groundwater Monitoring Wells Four shallow borings will be advanced using 8 -inch diameter hollow stem augers to approximately 27 feet bgs. Upon completion a 2 -inch diameter groundwater monitoring well will be installed. It is anticipated that the groundwater monitoring well will be screened from approximately 17 to 27 feet bgs. The actual screen and depth interval will be determined based on observations in the field. A generalized first encountered groundwater monitoring well construction detail is included as Figure 2. Deep Groundwater Monitoring Wells Soil samples will be field screened with a photo -ionization detector (PID). The soil ' screening procedures will involve measuring approximately 30 grams from a relatively undisturbed soil sample, placing this sample in a sealed container (zip -lock bag). The bag will be warmed in the sun for approximately 20 minutes, then the head ' space within the bag will be tested for total organic vapor, measured in parts per million (ppm: volume/volume). The PID results will be noted on the field boring logs. PID readings are useful for indicating relative levels of contamination, but can't be used to evaluate hydrocarbon levels with the confidence of laboratory results. Soil samples will not be collected for laboratory analysis during the advancement of the borings. Ms. Victoria McCartney July 12, 2007 Page: 3/5 In order to minimize the potential for cross -contamination between the shallow and deep zones, each of the four deep boreholes will be double -cased with conductor casing to approximately 45 feet bgs. The conductor casing will be advanced using 15.5 -inch diameter hollow stem augers. Once the conductor casing is set, a borehole will be advanced through the conductor casing to approximately 60 feet bgs using 8 -inch hollow stem augers to allow for the installation of the deep monitoring wells. Upon completion a 2 -inch diameter ' groundwater monitoring well will be installed. It is anticipated that the groundwater monitoring well will be screened from approximately 50 to 60 feet bgs. The actual screen depth and interval will be determined based on observations in the field. A generalized deep monitoring well construction detail is included as Figure 3. ' Soil Sampling and Screening Soil samples for logging purposes will be collected continuously for visual classification from 8 -feet 1 -inch bgs to the total borehole depth using either a California -modified split -spoon sampler, Simul-Probe or Enviro-Core sampler. Soil samples will be field screened with a photo -ionization detector (PID). The soil ' screening procedures will involve measuring approximately 30 grams from a relatively undisturbed soil sample, placing this sample in a sealed container (zip -lock bag). The bag will be warmed in the sun for approximately 20 minutes, then the head ' space within the bag will be tested for total organic vapor, measured in parts per million (ppm: volume/volume). The PID results will be noted on the field boring logs. PID readings are useful for indicating relative levels of contamination, but can't be used to evaluate hydrocarbon levels with the confidence of laboratory results. Soil samples will not be collected for laboratory analysis during the advancement of the borings. Ms. Victoria McCartney July 12, 2007 Page: 3/5