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• N"011 ATTACHMENT A FIELD AND LABORATORY PROCEDURES Exploratory Drilling The soil borings will be drilled using 8-inch hollow-stem auger drilling equipment to a depth of approximately 50 feet below ground surface (bgs) or to first encountered groundwater. The soil borings for the well installations will be drilled using 8-inch hollow-stem auger drilling equipment to a depth of approximately 65 feet bgs. The borings will be logged by a Pacific Environmental Group, Inc. geologist using the Unified Soil Classification System and standard geologic techniques. Soil samples for logging will be collected at 5-foot depth intervals using a California-modified split-spoon sampler. The sampler will be driven a maximum of 18 inches using a 140-pound hammer with a 30-inch drop. All soil samples for chemical analysis will be retained in brass liners, capped with Teflon squares and plastic end caps, taped, and sealed in clean zip-lock bags. The samples will be placed on ice for transport to the laboratory accompanied by chain-of-custody documentation. All down-hole drilling and sampling equipment will be steam-cleaned following the completion of the soil boring. Down-hole sampling equipment will be washed in a tri-sodium phosphate or alconox solution between samples. Groundwater Monitoring Well Installation The boring will be converted into a groundwater monitoring well by installing 2-inch diameter, flush-threaded, Schedule 40 PVC casing with 0.020-inch factory-slotted screen. Approxi- mately 20 to 30 feet of screen will be placed in the bottom of the boring. An RMC Lonestar 2/12 sand pack, or equivalent, will be placed in the annular space across the entire screened interval, and will extend approximately 2 to 3 feet above the top of the screen for the well. A bentonite and Portland cement seal will extend from the sand pack to the ground surface. The boring logs will show well construction details. The groundwater monitoring well will be developed after completion. The development procedure for the well will consist of surging the well and pumping or bailing water from the well until the water is visibly clear, or until a minimum of ten casing volumes have been removed. 9200391A/WPLAN A- 1 January 10, 1996