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1 <br /> 1 <br /> ATTACHMENT C <br /> FIELD AND LABORATORY PROCEDURES <br /> 1 <br />' Exploratory Drilling and Soil Sampling <br /> The soil bonngs were drilled using 10-inch hollow-stem auger drilling equipment Borings <br />' were logged by a SECOR International Incorporated scientist using the Unified Soil <br /> Classification System and standard geologic techniques under the direction of a registered <br />' geologist Soil samples for logging were collected at 5-foot depth intervals using a <br /> California-modified split-spoon sampler Soil samples were collected by advancing 2-inch- <br /> diameter brass sample liners into undisturbed soil, reached through the center of the drill <br />' auger The sampler was driven a maximum of 18 inches using a 140-pound hammer with a <br /> 30-inch drop Soil samples for chemical analysis were retained in brass liners, capped with <br /> Teflon squares and plastic end caps, and sealed in clean zip-lock bags The samples were <br />'• placed on ice for transport to the laboratory accompanied by chain-of-custody documentation <br /> Down-hole drilling and sampling equipment was steam-cleaned prior to and following the <br />' completion of each soil boring Down-hole sampling equipment was washed in a tri-sodium <br /> phosphate or alconox solution between samples <br />' Groundwater Monitoring Well Installation and Development <br /> Each of the groundwater monitoring wells was constructed of 4-inch schedule 40 PVC blank <br />' casing and 0 020-inch-slot well screen with flush threads A #3-sand filter pack was installed <br /> in the annulus from the bottom of each borehole to at least 2 feet above the top of the well <br /> screen, followed by a well seal consisting of a 2-foot-thick hydrated bentonite layer overlain <br />' by grout to ground surface Each well was secured by a locking expandable well cap and <br /> fitted with a traffic-rated well box set in concrete <br /> During development the wells became dry after purging approximately three well casing <br /> volumes The recharged well water displayed little or no turbidity Subsequently, the wells <br /> were sampled after eighty percent recharge If the wells display turbidity during the next <br /> sampling event the wells will be redeveloped <br /> • <br />