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DocuSign Envelope ID:81 E05E8E-EED7-43D3-8B8A-0811 OE72140A <br /> SECTION 33 34 00 - FORCE MAINS <br /> C. Where soil conditions prohibit vertical walls, the trench width at the bottom and to 1' <br /> above the top of the pipe shall be as specified above with the remainder being held to the <br /> least possible width greater than that specified. Where soil conditions prevent ditch <br /> excavation without excessive widths, or where directed by the Engineer, wood or steel <br /> sheeting, as hereinafter specified, shall be driven to support the trench walls, or a suitably <br /> reinforced steel trench box shall be employed. <br /> D. Trench bottoms shall be hand graded to provide uniform and continuous bearing for the <br /> pipe along its entire length, with bell holes being dug for pipe bells. No ridges, sags or <br /> undercutting will be allowed. <br /> E. If approved by the Engineer and subject to suitable solid conditions, the trench may be <br /> excavated a few inches below the established subgrade and backfilled with selected <br /> materials (from the excavation, if available)well compacted and so shaped as to give the <br /> pipes uniform bearing throughout their lengths at the established grade. Bell holes shall <br /> be dug to relieve the bells of load and to provide for completing the joints. <br /> F. Where the material at grade is unstable, soft, and incapable of supporting the pipe, the <br /> trench shall be excavated below grade, as directed by the Engineer, and refilled to grade <br /> with crusher-run stone or gravel so as to form a firm foundation for the pipe. None shall <br /> be compacted and graded so as to provide stable foundation and a uniform bearing for <br /> the pipe. Bell holes shall be provided as in other types of foundations. <br /> G. Where the material excavated from the trench is unsuitable for backfill material, it shall be <br /> hauled off and disposed of and selected material hauled in for backfilling the trench. <br /> H. Should ground water be encountered in the bottom of the trench, causing the trench <br /> bottom to be unstable the material, as directed by the Engineer shall be excavated below <br /> grade sufficiently to allow a bed of crushed rock or gravel to be placed in which to bed the <br /> pipe. The work shall be done as for unstable foundations. The depth of cut below grade <br /> shall be only the minimum amount to accomplish the purpose, and shall be as directed by <br /> the Engineer. <br /> I. The Contractor shall furnish all machinery for pumping, bailing, and/or pointing and shall <br /> pump, bail, or otherwise remove any water which may be found or shall accumulate in <br /> the trenches, and shall perform all work necessary to keep them clear of water while the <br /> pipe is being laid. The disposal of water after removal shall be satisfactory to the <br /> Engineer. <br /> J. Whenever necessary, the side of the trench shall be braced and rendered secure and <br /> either open or close sheeting used to the satisfaction of the Engineer; such sheeting and <br /> bracing to be left in place until the trench is refilled to a safe limit, not less than 2' above <br /> the top of the pipe. The top portion may then be cut off, but the lower portion shall <br /> remain undisturbed. In lieu of sheeting, suitable trench boxes may be employed. All <br /> sheeting, bracing, trench boxes, and trench construction methods shall conform to the <br /> latest Department of Labor Safety and Health Regulations for construction promulgated <br /> under the Occupational Safety and Health Act of 1970. No extra payment will be made <br /> for sheeting and bracing. Such cost shall be included in the cost of installing the pipe. <br /> K. In rock or other unyielding material, the excavation shall be made at least 6" below <br /> subgrade elevation. The trench shall be refilled with select material compacted in place <br /> as specified for ordinary excavation. Suitable material from excavation may be used, if <br /> available. If not, it shall be hauled in. <br /> L. If rock is encountered, it shall be paid for at the unit price set forth in the Bid. Only solid <br /> rock requiring blasting or drilling for its removal will be classified as rock excavation. <br /> Orange County DAA PN R00592-225N2 <br /> Walnut Grove Wastewater System January, 2021 <br /> 33 34 00-13 <br />