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.,� ATTACHMENT 2 .Owl FIELD AND LABORATORY PROCEDURES Soil Borings and Sampling Two boreholes for the monitoring wells will be advanced by hollow-stem auger to depths of approximately 40 feet bgs. An attending geologist will log cuttings and sample in accordance with ASTM D-2488 - Standard Practice for Description and Identification of Soils (Visual-Manual Procedure). Soil samples collected for chemical analysis will be retained in brass liners, capped with Teflon squares and plastic end caps, and sealed in clean zip-lock bags. The samples will be placed on ice for transport to the laboratory accompanied by chain-of-custody record. Down-hole drilling and sampling equipment will be steam-cleaned prior to and following completion of each sample interval. Dewy►-hole- dritling-and sarrfpling`equipment-wilt`be"tteam-cleaned-,prior--to-and-following-completion-of each-sample-irtteNa I. Groundwater Monitoring Well Construction The wells will be constructed with flush-threaded 2-inch diameter, schedule 40 PVC with approximately 15 feet of 0.020-inch screen. The remaining portion of the well will be completed with 2-inch-diameter schedule 40 PVC flush-threaded casing to the surface. A filter pack will be placed in the annular space adjacent to the well screen and will be installed to approximately 2 feet above the top of the well screen. Between the filter pack and the cement/bentonite grout, 1 to 2 feet of bentonite pellets will be placed above the filter pack. Placed above the bentonite seal will be a 5% to 10% bentonite-cement grout mixture to ground surface, -using a tremie pipe to ensure proper: placement of grout material. The wellhead will be completed at ground surface with locking well caps and traffic-rated bolt-down well vaults. The vault will be installed slightly above the surrounding surface grade and finished with a cement apron to provide positive relief away from the wellhead. Organic Vapor Procedures Soil samples will be analyzed in the field for ionizable organic compounds using a photo- ionization detector (PID) with a 10.2 UV lamp or a flame ionization detector (FID). The test procedure will involve measuring approximately 30 grams from an undisturbed soil sample, placing this subsample in a sealed container (either a zip-lock bag or a mason jar). The container will be warmed for approximately 20 minutes (in the sun), then the head-space within will be tested for total organic vapor, measured in parts per million as benzene (ppm; volume/volume). The instrument will be calibrated prior to drilling using a 100-ppm isobutylene standard (in air) and a sensitivity factor of 55, which relates the photo-ionization potential of benzene to that of isobutylene at 100 ppm. PID and FID readings are useful for indicating relative levels of contamination, but cannot be used to evaluate hydrocarbon levels with the confidence of laboratory analyses.