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3 .03 ALIGNMENT, GRADE AND COVER FOR BURIED PIPING SYSTEMS <br /> A. Gravity sewers shall be laid and maintained to the required lines, depths, and <br /> grades . <br /> B . Wherever obstructions not indicated on the Drawings are encountered during the progress <br /> of the work and interfere to such an extent that an alteration in the Drawings is required, <br /> the Engineer will order a deviation from the line and grade or arrange with the Owners <br /> of the structures for the removal, relocation, or reconstruction of the obstructions . <br /> C. The maximum permissible deflection for pipe and fittings shall be as recommended by the <br /> manufacturer. <br /> D. Installation of gravity sewers shall be controlled by use of a laser to maintain proper grade. <br /> The Contractor shall also be responsible for verifying elevations of the pipe, as <br /> indicated on the Drawings, at sufficient points during progress of the work to identify <br /> discrepancies between actual and plan elevations due to laser misalignment, equipment <br /> error, etc. , and to correct the work as required to conform to the Drawings . <br /> 3 . 04 PIPE TRENCH EXCAVATION <br /> A. Trench Dimensions <br /> 1 . The minimum width of the trench shall be equal to the outside diameter of the pipe at <br /> the joints plus 8 inches for unsheeted trenches, or 12 inches for sheeted trench, and <br /> the maximum width of trench, measured at the top of the pipe, shall not exceed <br /> the nominal pipe diameter plus two feet, unless otherwise shown on the Drawing <br /> details or approved by the Engineer. Trench walls shall be vertical from the bottom <br /> of the trench to a line measured one foot above the top of the pipe. From one foot <br /> above the top of the pipe to the surface, the trench walls shall be as nearly <br /> vertical as soil conditions will permit, unless otherwise detailed on the Drawings. <br /> Spaces for joints, fittings, manholes and other structures shall be maintained <br /> unless otherwise approved by the Engineer, or alternate methods are detailed on <br /> the Drawings . Should the specified maximum width of trench be exceeded, the pipe <br /> shall be adequately reinforced as directed by the Engineer, at the Contractor's expense. <br /> 2 . Trench grade for utilities or structures not requiring special bedding material shall <br /> be defined as the grade of the bottom surface of the utility or structure to be <br /> constructed or placed within the trench. Such shaping of the trench bottom, as <br /> may be required to provide suitable bedding, shall be considered to be a part of this <br /> work. Trench grade in non-cushioning material shall be defined as 6 inches below the <br /> outside of the bottom of the utility, which 6 inches shall be backfilled with suitable <br /> bedding material . Unauthorized excavation below trench grade shall be backfilled to <br /> trench grade and suitably compacted by the Contractor without additional cost to the <br /> Owner. Final trimming and grading of trench bottom shall be done manually. <br /> 3 . 05 BACKFILL AND BEDDING MATERIALS <br /> A. TYPE 1 - Type 1 material shall be either well-graded crushed stone or crushed gravel <br /> meeting the requirements of ASTM Designation C33-71a, Gradation 67 (3/4 inch to No. <br /> 02530 — Gravity Sanitary Sewer Piping <br /> 02530- 4 <br />