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the maximum trench width shall not exceed 36' plus the outside pipe diameter unless approval <br /> ' to the contrary is given by the Engineer. Trench widths will be measured between faces of the <br /> cut at the top of the pipe. <br /> Where no special bedding is required, trench bottoms may be machine excavated to slightly <br /> above grade and cut down to pipe grade by hand in the fine-grading operation. Should the <br /> trench bottom be inadvertently cut below grade, it shall be filled to grade with#67 washed stone <br /> tamped. <br /> Length of trench open ahead of pipe laying shall be not more than 300 feet, and no less than 20 <br /> feet unless approval is obtained from the Engineer. Contractor shall open no more trench than <br /> can be covered by end of working day. <br /> Wet trenches or those with unstable subgrade shall be stabilized by the use of No. 67 stone. <br /> ' The Contractor shall keep all trenches free from water during excavation for pipelines. The <br /> water shall be pumped out of the ditch or dams built to keep it out of the ditch in such a manner <br /> as not to cause injury to the public health, private property, or the work in progress. <br /> Portable bridges shall be erected across trenches, wherever the Engineer deems them <br /> necessary to permit the passage of vehicular and/or pedestrian traffic. <br /> ' The local Fire Department and 911 shall be notified at least 24 hours before any street is <br /> blocked by the opening of a trench. The Fire Department and 911 shall also be notified when <br /> the street is once again open to traffic. The contractor shall provide all temporary signage and <br /> barricades which may be required by the Fire Department or the Department of Transportation. <br /> Sheeting or bracing shall be used wherever necessary to prevent caving of the trench banks. <br /> ' The removal of sheeting shall be done in such a manner as to minimize the loss of friction <br /> between the trench walls and the backfill. Sheeting shall be cut off and left in place where its <br /> removal will adversely affect the pipeline installation. <br /> 6. Rock Excavation in Trenches. Should rock be encountered in the trenches, the excavation <br /> shall be carried to a depth of 6"below the body of the t)ipe and the trench shall be brought back <br /> to grade with No. 67 Stone properly compacted. Suitable backfill material shall be defined as <br /> ' stabilization stone, sand, or native material free from rocks of optimum moisture content in order <br /> to obtain a compaction of 95% standard proctor. The use of native material shall be subject to <br /> the sole approval of the Engineer or his representative. <br /> ' Should rock be encountered in the trenches and blasting is required for its removal, then all <br /> blasting operations shall be conducted in strict accordance with existing ordinances and <br /> accepted safe practices relative to the storage and use of explosives. <br /> ' No rock excavated from trenches larger than 3"diameter shall be used to backfill such trenches <br /> and no rock is allowed in the first 24" above the top of the pipe. The items named for the <br /> ' various sizes and classifications of pipe to be installed shall include the removal and disposal off <br /> site of such excavated rock material. The contractor shall secure, haul, and place in the trench <br /> sufficient suitable backfill material. Suitable backfill material is defined as stabilization stone, <br /> sand or native material free from rocks of optimum moisture content in order to compact to 95% <br /> ' of standard proctor. <br /> ' SANITARY SEWER LINES: DETAILED SPECIFICATIONS FOR INSTALLATION SS-3 <br /> 10/15/09 <br />