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With the work platform of the scaffolding lowered into position near the weir crest , the weir <br /> operator will remove the lag screws that have connected each board to the flange extension and remove <br /> the top board with a pry bar. Through this process , the weir operator must take care to minimize damage <br /> to the board and spline. All boards and splines removed intact and with minimal damage should then be <br /> stacked neatly on a level surface with spacers separating each level to promote air-drying . The contractor <br /> should use these boards and splines removed intact to close off the weirs following the completion of <br /> decanting. However, if swelling of the board or spline prevents the operator from prying the top board <br /> from the one beneath intact, the operator may remove the top board by cutting it into several sections with <br /> a chain saw or cordless electric saw and knocking the sections loose with a sledge . All boards and splines <br /> removed in such a manner must be discarded offsite in an approved manner. <br /> 2. 3. 3 Seaffolding/Ladders <br /> To provide safe access to the weir boards and a secure working platform from which to perform <br /> the now more complex weir board installation procedure, the contractor must provide an approved, <br /> OSHA -compliant , moveable scaffolding system, similar to those in wide commercial use for painting or <br /> window-washing. The scaffolding must be suspended by ropes or cables from contractor-installed, <br /> wooden or steel cantilevered beams permanently fastened to the 3 " x 12 " bridging that supports the <br /> walkway deck stringers, or to the wooden support piles themselves . The specific strength requirements <br /> and fittings for the beams will depend on the requirements of the specific scaffolding system employed . <br /> The scaffolding must provide access to the full span of the three stack weir system, either through the use <br /> of a single scaffolding platform that may be moved from one stack to another or multiple platforms that <br /> can provide access to all three stacks simultaneously . The contractor must use the scaffolding to lower the <br /> weir boards to be installed from the weir walkway to a position near the weir crest from which the weir <br /> operator may safely install additional weir boards . <br /> Installation of the scaffolding will require removal of the existing ladder system that presently <br /> extends from the walkway down the upstream face of each weir stack. This must be replaced with a <br /> ladder system, either fixed or movable, on the inside of each weir stack that will allow the operator to <br /> access the back (downstream) side of the weir boards, if necessary to install the weir boards and attach <br /> each board to the flange extension. <br /> - 1t - <br />