(A) The width of the trench shall be six inches minimum on each side of the pipe bell for a distance at least two feet above the top of the pipe. The sides of the trench shall be kept as nearly vertical as practicable within the limits of excavating codes.
(B) Trench bottom shall be carefully excavated to the specified, and level trench bottom to provide uniform bearing and support for full length of pipe; provide bell holes at each pipe joint; and allow access completely around circumference of pipe for proper joining operations. Trench bottom shall conform to best construction practice as recommended by pipe manufacturer.
(C) Trench bottoms carried below required grade shall be backfilled to proper elevations with IDOT gradation three gravel or crushed stone as specified for pipe bedding, compacted to 95% standard proctor density.
(D) When unstable material is encountered which may not provide a suitable foundation for the pipe, the engineer shall be notified immediately so that he or she may investigate the questionable material to determine its suitability for pipe foundation. If the material is considered unsuitable for foundations, the engineer will specify and authorize remedial measures in writing.
(E) If the removal of unsuitable material is authorized, it shall be replaced with trench stabilizing material. A minimum of four inches of pipe bedding cushion shall be provided on top of the stabilizing material to prevent point loading.
(F) Over-excavation of unsuitable material and replacement with suitable bedding material within payment lines shall be measured by the engineer and paid for by the cubic yard.
(G) Any excavation under or around utilities, where overhead clearance prevents the use of a machine, or under trees and shrubs where shown on the plans, shall be excavated by hand.