(A) The trench shall be excavated to an elevation of four inches below the bottom of the pipe and so that the flow line of the finished sewer will be at the depth and grade specified or established by the Engineer.
(B) Well compacted moist fine aggregate bedding material, at least four inches in depth below the pipe, shall be placed the entire width of the trench and for the length of the pipe. The fine aggregate shall meet the approval of the Engineer and shall be compacted to his satisfaction by ramming or tamping with tolls approved by the Engineer.
(C) When pipe having bells or hubs is used, cross trenches, not more than two inches wider than the bell or hub, shall be excavated to provide uniform bearing along the length of the pipe.
(D) If the excavation has been made deeper than necessary, the foundation shall be brought to the proper grade by the addition of well compacted bedding material.
(E) Where a firm foundation is not encountered at the grade established, due to soft, spongy, or other unsuitable soil, all such unsuitable soil under the pipe and for the width of the trench shall be removed and replaced with well compacted bedding material.
(F) Where rock, in either ledge or boulder formation, is encountered, it shall be removed below grade and replaced with a cushion of well compacted bedding material having a thickness under the pipe of not less than eight inches.
(G) Concrete Cradle. Where sub-grade conditions, in the opinion of the Engineer, warrant extra precautions for the bedding of pipe, the Engineer may require the construction of a concrete cradle to be installed in conformance with the size and dimensions indicated on the plans. All concrete used in concrete cradle shall have a minimum compressive strength of 2,500 psi at 28 days.