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Page 2 <br /> Borings and Monitoring Wells <br /> Borings would be used to visually identify soil type and to recover samples for physical <br /> testing. Borings will be drilled using wet rotary drilling methods and hollow-stem augers. <br /> Cuttings will be removed from the site. <br /> The geotechnical engineer is tasked with developing final recommendations for the levee <br /> design ahead of the other project components. To check the strength of soil beneath the <br /> planned toe of the new levee, in addition to exploration proposed from the existing roads, <br /> they will need to drill three borings in the field where the levee will be constructed. Special <br /> track-mounted drilling equipment will be used. A boring also needs to be drilled for the Old <br /> River tunnel shaft. The shaft site is within one of the fields. The geotechnical engineer <br /> would like to drill the exploratory boring at the planned tunnel shaft site while they have the <br /> (specialized equipment on site. CCWD seeks your permission for the geotechnical engineer <br /> and his driller to enter your fields at these locations. <br /> Two different rigs will be used for drilling. A truck-mounted rig (likely the same one used in <br /> April 2005)will drill borings from roads. As done in the past, the rig will set up on one side <br /> of the road to allow other farm traffic to pass. A track-mounted rig would be used to drill <br /> borings off the road. Each rig would have a service truck and the track-mounted rig would <br /> come on a trailer. Each rig would have a 2-person drill crew and one engineer. The <br /> geotechnical engineer expects to have only one rig on site at any one time. Most borings <br /> will take 5 to 8 hours to drill and grout. <br /> Borings for the Intake Structure and Setback Levee: Four rotary wash borings will be <br /> drilled from the roads at the Intake Structure/Setback Levee site. One boring about 100 feet <br /> deep will be drilled from the levee crest, a second boring 40 to 60 feet deep will be drilled at <br /> the toe of the levee. Two borings will be drilled from the ditch access path north of the toe <br /> ditch. <br /> S 6,n,,,,,y Three rotary wash borings will be drilled using the track-mounted equipment in the fields, <br /> near the planned toe of the Setback Levee. <br /> �00V <br /> Borings and Monitoring Wells for the Pipeline Alignments: Three borings will be drilled <br /> �v--' to 40 feet deep from the existing farm roads using a truck-mounted rig with hollow stem <br /> augers. The exploration will extend far below the bottom of the pipe trench to provide data <br /> for design of a dewatering system. <br /> �p1Y, <br /> Groundwater monitoring wells will be installed in the4hfee hollow stem auger borings. Tops <br /> of the monitoring wells can be in flush-mounted utility boxes (Christie boxes) or in risers that <br /> stick up three feet above grade. The top conditions can be your choice. The borings to be <br /> converted to monitoring well can be drilled at the edge of the roads to avoid interference <br /> with farm traffic. CCWD proposes that the monitoring wells will remain in place for at least <br /> six months to allow two quarters of groundwater sampling. When the monitoring wells are <br /> no longer needed, they will be removed by drilling out the casing and backfilling with grout. <br /> 59205 Field ExplorationUr_draft_KW-EH.cpm rev07.20.06 <br />