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F. Drilling shall be completed using the sonic drilling method. Drilling shall include a <br /> minimum borehole diameter of 12-inches to a minimum depth of 210 feet below <br /> ground surface. <br /> G. Core samples shall be recovered and preserved in appropriate plastic bags, <br /> supplied by the Contractor. Core samples shall be collected in 5-foot lengths and <br /> laid on the ground for the Engineer's inspection. Core samples shall be laid out <br /> in an organized manner so that the depth of each bag of cuttings can be easily <br /> discerned in the field. <br /> H. The Engineer will log the core sample material at every 5-foot interval based on <br /> the characterization of these samples per USCS classification. <br /> I. If the borehole is over-drilled, the bottom of the hole shall be filled with sand to <br /> raise the bottom of the hole, as directed by the Engineer. <br /> J. Uncompleted Borings <br /> 1. If there is an interruption in work, such as overnight shutdown or inclement <br /> weather, the Contractor shall: <br /> a Measure and record the depth of uncompleted borings left overnight. <br /> b Cover the well opening with a watertight uncontaminated cover with the <br /> following methods: <br /> • Cover the boring with a %-inch thick 4x8 plywood or a steel plate 2ft x <br /> 2ft in size. Contractor shall place bentonite around plywood or steel <br /> covers if used. The plywood or steel cover shall be secured in place <br /> or weighted down so that it cannot be tampered or blown away by the <br /> wind. <br /> c Direct all surface runoff away from the boring. <br /> d Cordon-off the work area with safety cones and caution tape to the <br /> satisfaction of the Engineer. <br /> 2. Contractor shall verify the depth of the well the next day by measuring with the <br /> weighted tape. If the boring has collapsed, then the Contractor shall re-drill the <br /> boring at no additional cost to the County. <br /> K. ABANDONED BORINGS <br /> 1. If an obstruction or other condition is encountered that prevents the drilling or <br /> installation of a well at the location identified, the Engineer may request that the <br /> Contractor abandon the boring. If directed to do so, the Contractor shall fill the <br /> borehole with neat cement. Neat cement shall be placed using a tremie pipe <br /> installed within 10 feet of the bottom of the borehole to prevent freefall conditions <br /> North County G-15&G-16 San Joaquin County <br /> Groundwater Monitoring Well Specifications 6 Public Works Dept <br /> Solid Waste Division <br />