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7) BEDDING AND FOUNDATIONS A) CLASS A (CONCRETE CRADLE OR CONCRETE ARCH BEDDING ) 1 ) This class of bedding shall be used only where specifically shown in the Drawings or directed by the Engineer. If the use of a concrete cradle is required the pipe shall be bedded in a monolithic cradle of a 1 , 500 PSI concrete with a minimum thickness equal to 1 /4 the outside pipe diameter or to a minimum of four inches under the barrel , whichever is greatest, and extending up to the sides of the pipe to a height equal to 1 /2 of the outside pipe diameter. The cradle shall have an overall width equal to 1 - 1 /4 of the outside diameter of the pipe or a minimum width equal to the outside diameter of the pipe plus eight inches , whichever is greater. 2) If a concrete arch is required , the pipe shall be embedded in carefully compacted Type 1 material having a minimum thickness equal to 1 /4 the outside pipe diameter or to a minimum of four inches under the barrel , which ever is greater, and extending up the sides for a height equal to 1 /2 of the outside pipe diameter. The top half of the pike shall be covered with a monolithic Class C concrete arch having a . minimum thickness equal to 1 /4 the outside diameter of the pipe or a minimum of four inches over the crown of the pipe , whichever is greater, and extending down the sides for a depth equal to 1 /2 of the outside pipe diameter. The arch shall have an over all width equal to 1 1 /4 of the outside diameter of the pipe or a minimum width equal to the outside diameter of the pipe plus eight inches , whichever is greater. B) CLASS B (FIRST-CLASS BEDDING ) 1 ) Where Class B Bedding is required , the trench shall be excavated below the planned bottom of the pipe to a depth equal to 1 /4 the nominal diameter of the pipe , or 6 inches , whichever is greater. The over excavated depth shall be backfilled using either Type 1 or Type 3 materials carefully compacted and shaped using hand tools so as to provide a uniform support for the lower portion of the pipe barrel . Shaping under the pipe bells shall be so that the bell does not support the pipe and joints can be made without bedding material interference . 2 ) At the option of the Contractor, Class B Bedding may be used in place of Class C (Ordinary Bedding ) provided that the exercise of this option shall create no additional expense to the Owner. The Contractor shall notify the Engineer in writing of those portions of the project on which he proposes to exercise this option . C) CLASS C (ORDINARY BEDDING ) 1 ) The bottom of the trench shall be hand shaped to provide a firm bedding for the utility pipe . The utility shall be firmly bedded in undisturbed firm soil . The bedding shall be shaped so that the pipe will be in continuous contact therewith for its full length and shall provide a minimum bottom segment for the pipe equal to 0 . 6 of the outside diameter of the barrel . Excavation under the bell shall be sufficient so that the bell does not support the pipe and the joint can be made without interference . D) UNSUITABLE BEDDING MATERIAL 1 ) Class C Bedding shall be used for all pipeline construction unless otherwise shown on the Drawings or unless unsuitable material is encountered at the bedding surface . In the event that the materials encountered at normal bottom of trench excavation are , in the judgment of the Engineer, unsuitable to act as foundation for the pipe , such material shall be excavated for the full width of the trench to the depth necessary to obtain a suitable foundation . The Engineer will notify the Contractor, in writing , of the necessity for and extent of the material to be removed and the Contractor shall remove such unsuitable material as soon as possible - D-3-3