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Soil Investigations for Data Collection in the Delta Initial Study/Proposed Mitigated Negative Declaration 21 The drilling fluids will be kept in the closed system formed by the conductor casing, a tank on the barge or drill ship deck, and a heavy plastic sleeve over the conductor casing which drapes into an external mud tank. This system will provide a reliable seal and prevent significant spillage of the drilling fluid into the water. The drill rod and sample rod connections will be disconnected either directly over the conductor casing or the recirculation tank. Furthermore, positive barriers consisting of hay waddles and/or other suitable type of spill-stoppage materials will be placed around the work area on the barge and ship decks. Drill cuttings that settle out in the recirculation tank will be collected into 55-gallon storage drums or larger bins. Good work practices and mitigation measure implementation will be observed and maintained in containing the drilling fluid, including taking care when transferring drill cuttings from the recirculation tank to the drums. The drums will be placed adjacent to the recirculation tank. If drilling fluid or drill cuttings material accidently spill onto the barge or drill ship deck outside of the containment area, they will be immediately picked up with a flat blade shovel and placed either into the recirculation tank or a storage drum, and the affected area will then be cleaned and mopped. Discarded soil samples will also be placed in the storage drums. Soil samples will be collected from borings using a standard penetration test (SPT) barrel (split spoon sampler), Modified California sampler, Pitcher Barrel sampler, 101 mm Geobarrel, 134 mm Geobarrel, Shelby tubes, and grab samples of the cuttings. The barge or ship will be mobilized from an established marina and will be anchored either at the Impact Areas or at Coast Guard established anchorage points. Personnel will access the barge and/or ship via a support boat from an established marina. Disturbance to the riverbank or levee banks will be limited to the minimum necessary to complete the work. The duration of investigation activities will be up to 15 days at each site. Following completion of a soil investigation, the boring will be grouted from the bottom of the borehole to within approximately 10 to 15 feet of the top with 5 percent (by weight) bentonite and 95 percent (by weight) cement grout. Water will first be introduced inside the drilled hole and circulated within the conductor casing to clear out any remaining drilling mud prior to grouting. Grouting of the drilled hole will be accomplished by lowering a pipe into the bottom of the borehole to pump grout into the bottom of the hole (tremie method). Grout will be placed from the bottom of the hole upward to a depth of approximately 10 feet below the bottom of the slough or river based on a calculated grout take volume to prevent grout migration into the slough or river water. At the completion of the grouting, the conductor casing will then be pulled out of the channel bottom to complete the overwater boring operation.