Whenever the ground is sufficiently firm and unyielding, the masonry or pipes shall be laid directly on the bottom of the excavation and, in the case of pipes, if the foundation is good earth, it shall be pared or molded to give a full support to the lower half of each pipe.
When so designated on the drawings or ordered by the Engineer, excavated areas shall be strengthened for foundation purposes by furnishing and placing crushed rock or gravel refill, timber cradles, timber piling or a combination of these materials Crushed rock or gravel to stabilize a foundation shall have a minimum size of one inch and a maximum size of two and one- half inches, well graded between these limits. The minimum thickness of a layer installed shall be eight inches.
Timber cradles shall be fabricated and placed to the details shown on the drawings or as ordered by the Engineer. Lumber for planking, timbering or bracing shall be No. 2 common yard lumber for timber in size less than six-inch nominal, and common structural grade for timbers over six inches nominal. Minimum planking thickness shall be two-inch nominal. All cradle lumber and planking shall be sawn or hewn with square corners and shall be free from worm holes, loose knots, wind shakes, decayed or unsound portions or other defects which might impair their strength or tightness. All lumber and timber shall be subject to inspection and approval by the Engineer before it is incorporated in the finished work.
When so designated on the drawings or ordered by the Engineer, the contractor shall furnish and place piling foundations. Piling shall be driven in a manner acceptable to the Engineer. The contractor is hereby advised to purchase piling so designated or ordered only after a test pile or piles have been placed. When piling is required, the contractor, when ordered by the Engineer, shall furnish and place test piles in a location designated by the Engineer. The bearing value of driven piles shall be computed on the basis of the Engineering News Record Formula.
For piling not shown on the drawings, piling shall be supplied and driven to the bearing value designated by the Engineer. When so ordered by the Engineer, the contractor shall furnish and place framework and loading for an actual test load on the pile.
(Ord. 352. Passed 10-22-62.)