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• ATTACHMENT F FIELD AND LABORATORY PROCEDURES Exploratory Drilling The soil borings for the shallow well installations were drilled to depths of approximately 65 feet below ground surface (bgs) The boring for the deeper well were drilled to approximately 90 feet bgs Borings were drilled using 8 -inch hollow -stem auger drilling equipment and logged by a SECOR geologist using the Unified Soil Classification System and standard geologic techniquts Soil samples for logging was collected at 5 -foot depth intervals using a California -modified spht- 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 -hale drilling and sampling equipment was steam -cleaned following the completion of the soil boring 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 installing 2 -inch diameter, flush - threaded, Schedule 40 PVC casing with 0 020 -inch factory -slotted screen Approximately 12 feet of screen was placed in the bottom of the shallow borings Approximately 5 feet of screen was placed in the bottom of the deep boring An RMC 2112 sand pack, or equivalent, was placed in the annular space across the entire screened interval, and extends approximately 1 to 2 feet above the top of the screen for the well A bentonite and Portland cement seal was extend from the sand pack to the ground surface The boring logs show well construction details The wells were developed and sampled after completion The development procedure for each well consisted of pumping or bailing water from the well until the water is visibly clear, the well goes dry, or until a maximum of casing volumes have been removed After development, water levels were allowed to partially recover Groundwater samples were then collected using a disposable teflon bailer, placed into appropriate EPA -approved containers, labeled, placed on ice, and transported to the laboratory accompanied by cham-of-custody documentation The newly installed wells were surveyed by a California State Licensed Surveyor The well casings were surveyed to the nearest 0 01 feet in elevation to a known benchmark C7