[Amended 5-3-2010 ATM by Art. 28]
In ledge excavation, the contractor shall backfill and mechanically tamp to within 12 inches of the surface. The remaining 12 inches shall be good, clean, sharp gravel and shall be thoroughly tamped with a mechanical tamper. If, in the opinion of the Director of Public Works, the backfill should be puddled, the contractor shall do so. If the trench excavation is entirely of wet clay, the contractor shall replace the clay excavation with good, clean, sharp bank gravel and thoroughly tamp with a mechanical tamper in layers of twelve-inch depths to the surface of the highway. In all cases where the clay is comparatively dry, the contractor may backfill with said clay and thoroughly tamp with a mechanical tamper in layers of twelve-inch depths to a point 12 inches down from the surface of the highway. This twelve-inch section shall be filled with good, clean, sharp bank gravel and thoroughly tamped with a mechanical tamper.