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�s ATTACHMENT A FIELD AND LABORATORY PROCEDURES Exploratory Drilling The soil borings for well installation were drilled using 8-inch hollow-stem auger drilling equipment to a depth of approximately 25-feet below ground surface (bgs) The borings were logged by an IT Corporation geologist using the Unified Soil Classilication System and stan- dard geologic techniques Soil samples for logging were collected at 5-foot depth intervals using a California-modified split-spoon sampler The sampler was driven a maximum of 18 inches using a 140-pound hammer with a 30-inch drop All soil samples for chemical analysis were retained in brass liners, capped with Teflon squares and plastic end caps, and sealed in clean zip-lock bags The samples were placed on ice for transport to the laboratory accompanied by chain-of-custody documentation All down-hole drilling and sampling equipment was steam-cleaned following the completion of each soil bormg Down-hole sampling equipment was washed in a tri-sodium phosphate or alconox solution between samples . Groundwater Monitoring Well Installation The borings were converted to groundwater monitoring wells by mstalhng 2-inch diameter, flush-threaded, Schedule 40 PVC casing with 0 020-meb factory-slotted screen Approximately 20-feet of screen was used in well construction and was placed approximately 5 feet above to 15 feet below first encountered groundwater A RMC#3 sand pack, or equivalent, was placed in the annular space across the entire screened interval, and was extend approximately 2 feet above the top of the screen for the well A one-foot bentonite transition seal was placed atop the sand pack, and a Portland cement seal vas extended one-foot from the bentonite transition seal to the ground surface The seal was emplaced through the center of the hollow-stem augers by pouring Portland cement trom the ground surface The boring logs show well construction details The groundwater monitoring wells were developed after completion The development procedure consisted of pumping or bailing water from the well until the water was visibly clear, the well went dry, or until a maximum of ten casing volumes was removed