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Section 02310 <br /> HORIZONTAL DIRECTIONAL DRILLING <br /> The Contractor shall employ his best efforts to maintain full annular circulation of drilling <br /> fluids.Drilling fluid returns at locations other than the entry and exit points shall be <br /> minimized. In the event that annular circulation is lost, the Contractor shall take steps to <br /> restore circulation. If inadvertent surface returns of drilling fluids occur, they shall be <br /> immediately contained with hand-placed barriers (i.e., hay bales, sandbags, silt fences, etc.) <br /> and collected using pumps, where practicable. If the amount of the surface returns is not <br /> great enough to be collected, the affected area shall be flushed with fresh water and the fluid <br /> will be allowed to dry and dissipate naturally. If the amount of surface return exceeds that <br /> which can be contained with hand-placed barriers, small collection sumps (less than 5 cubic <br /> yards)may be used. If the amount of surface return exceeds that which can be contained and <br /> collected in the small sumps, drilling operations will be suspended until surface return <br /> volumes can be brought under control. <br /> The Contractor shall develop the drilling plans and procedures to prevent/minimize the <br /> potential for inadvertent surface returns including controlling the drill advance rate. Drilling <br /> pressure, flow rate and mud loss shall be continuously monitored. <br /> The Contractor shall employ his best efforts to maintain full annular circulation of drilling <br /> fluids.In the event that annular circulation is lost, the Contractor shall take steps to restore <br /> circulation. These may include but not be limited to "sizing"the hole, reduction of flow <br /> rate, or modification of drilling fluid properties. <br /> In the event of loss of circulation and/or inadvertent discharge of drilling fluids outside the <br /> pilot hole, the Contractor assumes all liability for control and cleanup of such. The <br /> Contractor shall immediately notify the Construction Manager of any loss in circulation <br /> and/or inadvertent surface return. The District will be responsible for notifying all <br /> appropriate authorities including the RWQCB and USAGE. <br /> A backhoe or front end loader and vacuum truck(s) and/or vacuum systems shall be <br /> provided at all times during the drilling and pullback operations to quickly respond, contain <br /> and clean up any spills or inadvertent returns that may occur. <br /> In general, drilling will not be stopped due to circulation loss or inadvertent returns unless <br /> the returns pose a threat to public health, environmental health and safety or unless directed <br /> by the Construction Manager or governing authorities. <br /> Surface returns on land shall be immediately contained with hand placed barriers (i.e. hay <br /> bales, fiber rolls, gravel bags, silt fences, etc.) and collected using vacuum pumps. If the <br /> amount of the surface return exceeds that which can readily be contained and collected then <br /> drilling operations shall be suspended until the surface return volumes can be brought under <br /> control. The Contractor shall be responsible for the full cost of all associated standby time. <br /> Walnut Grove Sewer Project(Conformed) 02310-14 SAO 160401 <br /> March 2008 N:\sa0160401\Specs\WG Conform\Div 2\02310.doc <br />