2004-013.C - Laserfiche WebLink

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strength and durability. It shall be squared to the required dimension throughout its entire length. If required for the proper execution of the work where running sand, quicksand or other semi- fluid material difficult to handle is encountered, the timber sheeting shall be tongue and groove . The Contractor may, in lieu of sheeting, bracing and shoring to maintain the allowable trench widths , use a "trench box " ("trench shield" or "mule " ) provided pipe sections are secured downstream by a cable(s) stretched through and secured to the end section of pipe by means of a timber and a cable clamp , all materials being of adequate size and strength. The cable shall be held taut during the process of advancing the "box " . - This procedure may be used so long as, in the opinion of the Engineer, the work is proceeding satisfactorily. The Engineer may revoke permission to use the "trench box " at any time he feels unsatisfactory or inadequate work is being performed and the Contractor shall, without appeal, immediately begin using sheeting„ bracing and shoring to maintain the allowable trench widths . At all times , when soil conditions permit, the bottom edge of the "trench box " shall be no lower than the springline of the pipe, so as to not disturb the trench compaction when advancing the " trench box " . 5 . Placing of Excavated Material - All excavated materials shall be placed where indicated by the Engineer in such a manner as not to endanger the work and so that free access will be maintained at all times to all parts of the trench and to all fire hydrants and their gate valves in the vicinit Such material shall be neatly piled so as to interfere as little as possible with traffic . 6 . Drainage - The Contractor shall furnish sufficient pumping or other dewatering equipment and shall provide at his own expense satisfactory drainage whenever needed in trenches and other excavations during the progress of the work and its completion for inspection. Water shall not be allowed to flow over or raise upon any concrete, masonry or pipe until work has been inspected and the mortar or concrete has properly set . Unless otherwise permitted by the Engineer, the water table shall be lowered by the use of a well point system. Open trench pumping may be permitted only upon approval by the Engineer of the method of pumping and drainage to be used . If open trench pumping is approved, the water must be conveyed entirely through approved coarse mgterial placed below the bottom of the "Foundation" hereinafter described. The depth of this coarse material shall be determined by the Contractor and approved by the Engineer. Materials and workmanship used for the well point system shall be in keeping with the approved standard practice . The well point system shall function so as to enable pipe, concrete cradle and appurtenances to be installed without interference from running or standing water at the bottom of the trench . The E:\PSW\P\99-91 e\TechsSpecs\techspec-02501 . doc 02501 - 7