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Soil Investigations for Data Collection in the Delta Initial Study/Proposed Mitigated Negative Declaration 20 obstructions or utilities that could endanger or be impacted by the drilling operations (e.g. old piles, cables, pipelines, etc.). The driller will use a rotary drill rig mounted on a shallow-draft barge or ship. Multiple barges and/or ships may be operated concurrently. The barge or ship will be anchored into the bottom of the channel with two to four spuds or anchor lines to prevent the vessel from drifting while the work is being performed. The spuds are steel pipes mechanically lowered into the channel bottom. The anchor lines would be located near the 4 corners of the barge and set some distance away to anchor the vessel. The Proposed Project consists of 57 soil borings from up to 200 feet below the slough or river bottom (measured at the mudline). The drill apparatus is similar to the land-based apparatus described above and consists of a 6- to 8-inch-diameter conductor casing that extends from the barge or drill ship deck, through the water column, and into the soft sediments of the slough or river bottom. The casing is smaller than most piers and should not impede water flow or migration patterns of fish. All drilling rods, samplers, and other down-hole equipment will be fully enclosed within the casing, effectively separating all drilling equipment from the water. The borings will be advanced using mud rotary method and will be drilled and sampled to a maximum depth of approximately 200 feet below the bottom of the slough or river. In this case, the term “mud” refers to the use of drilling polymers and/or bentonite clay added to the boring to allow removal of drill cuttings and to stabilize the boring walls. Initially, the boring will be advanced by pushing an approximate 6- to 8-inch-diameter conductor casing, which will extend from the top of the barge or drill ship deck, to an approximate depth of 10 to 15 feet or more below the mud line of the slough or river channel. The conductor casing will be used to confine the drill fluid (“mud”) and cuttings within the drill hole and operating deck of the barge or drill ship and prevent any inadvertent spillage into the water. Soil samples will be collected from within the casing. The drill hole below the conductor casing will be approximately 3.5 to 7.0 inches in diameter. Only water will be circulated through the pumps and conductor casing when drilling and sampling within 15 to 20 feet of the slough or river mud line. For deeper drilling, the drilling fluid, consisting of a mixture of circulating water and drilling polymers and/or bentonite clay, will be introduced into the conductor casing via the drill string to create a more viscous drilling fluid (also called drilling mud). The drilling fluid will pass down the center of the drill rod to the cutting face in the formation being drilled and will return up the drilled hole with the suspended cuttings. The drilling fluids and cuttings will be confined by the borehole walls and the conductor casing. Return drill fluids will pass through the conductor casing to the barge or ship deck and then through a tee connection at the head of the conductor casing into the drilling fluid recirculation tank.