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Tank Abandonment Site Assessment Work Plan NuStar Stockton Terminal Stockton, CA Page Two Geologist. A direct push geoprobe drilling rig and hand auguring will be utilized for the advancement of the soil borings . Pre- cleaned drilling equipment will be used throughout the drilling operation to prevent potential cross contamination . SOIL SAMPLING A total of 26 undisturbed soil samples will be collected for selected chemical analyses . The soil samples will be collected using either a 6-inch long, 1 . 54nch O . D . drive sampler with 64nch stainless steel sample tubes or a 36-inch PVC sample sleeve placed inside the Geoprobe sampling device . The steel sample tubes will be sealed with Teflon tape and PVC caps . A six-inch section of the PVC sample tube will be removed and sealed with PVC caps . An adjacent section of the sample tube/sleeve will be used for OVA evaluation and lithologic characterization . GROUND WATER SAMPLING In the event ground water is encountered in the soil borings adjacent to the tank pit, one ground water sample will be collected for analytical testing . The groundwater sampling will be conducted using a Hydropunch® type groundwater sampler . The groundwater sampler has a retrievable stainless steel or disposable PVC screen with steel drop off tip . The groundwater sampler operates by advancing 1 . 75 - inch diameter hollow push rods with the filter tip in a closed configuration to the desired sampling interval . Once at the desired depth, the push rods are retracted, exposing the encased filter screen and allowing groundwater to infiltrate hydrostatically from the formation into the inlet screen . Dedicated Teflon tubing will be lowered into the water and connected to a peristaltic pump at surface to purge ground water within the well screen and collect the water sample . Approximately 1 liter of water will be purged prior to collecting the water sample . The sample will be collected in laboratory supplied containers directly from the pump effluent. The containers will be filled to eliminate air in the head space, sealed and placed on ice for transportation to the analyzing lab . The groundwater samples will be labeled with all pertinent sampling information, and then packed on ice for subsequent delivery to a California Department of Health Services (CDOHS ) -certified laboratory for analyses . Strict chain- of-custody protocol will be followed throughout field and laboratory procedures . ANALYTICAL TESTING Soil and ground water samples will be submitted to a State certified laboratory for analysis by California DHS modified EPA Method 8015 TPH gasoline and diesel carbon chain (C4 to C36) and by EPA