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'j1'�¢ p27rh`i 2.04 Loose Riprap or Riprap for Gabion type letdowns. t2 - a. Riprap shall be hard, durable rock that will not disintegrate upon exposure to the elements or be easily broken by handling, and shall be reasonably free from earth and other foreign materials. Individual stones shall be approximately rectangular in cross section and free from thin slabby pieces. The unit weight of the riprap shall be at least 140 pounds per cubic foot. Riprap used for loose rock letdowns shall range between 50 and 150 pounds, shall have a minimum dimension of 6 inches in any plane and a maximum of 12 inches. If gabions are used, they shall be filled with a stone gradation recommended by the gabion manufacturer. b. The proposed source of riprap shall be designated not less than 60 days before starting riprap placement. No riprap shall be used before review or approval of the designated source by the County. 2.05 Corrugated Metal Pipe Culverts for Temporary and Interim Stormwater Conveyance a. Bituminous coated corrugated metal pipe or aluminum culverts shall be furnished and installed complete with all jointing materials and necessary accessories. b. Materials shall conform to the applicable provisions of the "Specifications for Highway Materials" of the American Association of State Highway and Transportation Officials, as follows: 1. Circular pipe and pipe arches shall be AASHTO M-190, Type A, circumferentially or helically corrugated, galvanized, fully bituminous coated, 14 gauge. 2. Fittings and coupling bands shall be same material as pipe, with widths and construction as required by AASHTO M-36. 3. End sections shall be manufacturer's standard dimensions, details, and gauges. 2.06 Pipe Embedment a. Granular embedment shall be crushed rock or pea gravel with not less than 95 percent passing a 1/2 -inch sieve and not less than 95 percent retained on a No. 4 sieve; to be placed in not more than 6 -inch layers and compacted by slicing with a shovel or vibrating. b. Compact embedment shall be finely divided material free from debris, organic material, and stones, placed in uniform layers not more than 8 -inches thick, and compacted to 95 percent maximum density as determined by ASTM D698 or graded gravel. Granular embedment may be substituted for all or part of compacted embedment. c. Hand placed embedment shall be finely divided material free from debris and rocks. �.�- 4 nt:�:iaK!'i'. Cyt'; • 2.3-2 .:' •'}TIC7 l'Ar •yt?:l¶;'{M'MMIIPIMeltA irMr..-morhsnuxanr.cnrocawwtiw.-............•. ev0657104,I8.97 Tr 01.