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12-05 <br /> <br />12-06 <br /> <br />12-07 <br /> <br />12-08 <br /> <br />approval of the Engineer the Contractor may excavate the trench with <br />sloping walls starting at a point twelve inches (12") above the outside <br />top of the pipe. <br /> <br />Trench Depth: The trench shall be excavated to the depth specified on <br />the plans. The trench bottom shall be on a uniform grade and within <br />0.03 foot of the specified grade for gravity lines at a grade of 2% or <br />less and within 0.1 foot for all pressure lines and gravity lines at a <br />grade steeper than 2%. When unstable material is encountered at the <br />specified depth the trench shall be overexcavated an additional one foot <br />and backfilled with suitable material. Unstable material shall be soil <br />containing excessive amounts of water or organic matter in the opinion <br />of he Engineer. When rock is encountered the Contractor shall <br />overexcavate an additional six inches (6") and backfill with suitable <br />material. Backfill shall be as specified in Section 13. <br /> <br />Dewatering: The trench shall be maintained in a dry condition until <br />backfilling is completed. The Contractor shall furnish, install and <br />operate such equipment as may be necessary to maintain the trench in a <br />dry condition. Water shall be disposed of in such a manner as to cause <br />no damage to property or present no danger to traffic. <br /> <br />Utility Crossings: When trenching for gravity lines all known crossings <br />of main storm drains, sanitary sewers, telephone ducts, gas, water or <br />other utility lines shall be opened prior to trenching to determine the <br />exact elevations. On any individual gravity line trenching shall <br />commence in areas where there is a possibility of unknown utilities. <br />Grades of new installations are subject to adjustment to fit existing <br />conditions. Checking with Utility Companies prior to start will be <br />required, or liability will be assumed by Contractor. <br /> <br /> Measurement and Payment. No measurement of trench excavation will be <br /> made and payment will be included in the price per lineal foot for pipe. <br /> <br />CDS.1.11 12-2 <br /> <br /> <br />