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Section 02310 <br /> HORIZONTAL DIRECTIONAL DRILLING <br /> 3.08 PREREAMING <br /> The Contractor's prereaming operations shall be conducted to insure that a hole sufficient to <br /> accommodate the pipe pull section has been produced. At a minimum, the hole shall be <br /> prereamed to 150 percent of the outside diameter of the pipe pull section. Any damage to <br /> the pipe resulting from inadequate prereaming shall be the responsibility of the Contractor. <br /> Reaming may be accomplished by pulling or forward reaming the reaming tool through the <br /> hole. Forward reaming should not be performed without a lead string of drill pipe. <br /> 3.09 PULLBACK <br /> Pullback procedures shall be reviewed by the Construction Manager prior to pullback <br /> operations. The Contractor shall provide a minimum of seven (7) calendar days notice to the <br /> Construction Manager prior to initiating pullback operations to allow for public notification. <br /> Pullback of the casing pipe or the dual HDPE pipes through a single borehole shall be done <br /> in one continuous operation if possible. The contractor is responsible for pullback <br /> operations. If multiple pull back operations are necessary the contractor is responsible for <br /> overcoming the static friction and preventing a stuck pipe without over stressing the pulled <br /> pipes. <br /> The pipelines shall be preassembled prior to the pulling operation and shall be temporarily <br /> capped before the pulling operation to prevent any drilling fluid, water, or debris from <br /> entering the pipelines. The Contractor is responsible for coordinating with, and gaining <br /> approval from the District and the local authorities for scheduling and coordinating the <br /> pullback operations. <br /> Pipe string shall be placed on wood dunnage or rollers that will prevent damage to ground <br /> surfacing and to minimize the stress and friction imparted to the pipe during pull back. <br /> The HDPE pipes shall be filled with water during pullback to counteract external pipe <br /> buckling pressures and to achieve neutral buoyancy. <br /> Alternative buoyancy modification shall be used at the discretion of the Contractor. Any <br /> buoyancy modification procedure proposed for use shall be submitted to the Construction <br /> Manager for acceptance. No procedure may be used which has not been accepted by the <br /> Construction Manager. The Contractor is responsible for any damage to the pipeline <br /> resulting from buoyancy modification. <br /> The pull section shall be installed in the reamed hole in such a manner that external <br /> pressures on the pipe are minimized and an appropriate counter-balancing internal pressure <br /> Walnut Grove Sewer Project(Conformed) 02310-16 SA0160401 <br /> March 2008 NAsa0160401\Specs\WG Conform\Div 2\02310.doc <br />