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<br />This gradation is a composite of ASTM C-33 and USBR Concrete <br />Manual and represents a concrete sand as tested by AASHTO T27. <br />Atterberg limits shall comply with the following criteria: <br />Liquid Limit: Less than 5% <br />Plasticity Index: Less than 2% <br />2. Type 4 Material (Coarse Filter) <br />The Contractor may be able to use on-site materials from the area <br />near the river to obtain this material. He should be cognizant of the <br />fact that most materiel used to obtain Type 4 material will require <br />screening to obtain proper gradations. All Type 4 material shall <br />conform to the following criteria: <br />Size (mm) Sieve % Passing <br />~• <br />38.1 1-1/2" 100% <br />19.1 3/4" 55 - 75% <br />9.52 3/8" 25 - 45% <br />4.76 #4 10 - 25% <br />2.38 #8 0 - 10% <br />1.19 #16 0% <br />This test is to be performed in accordance with AASHTO T27. <br />PART 3 -EXECUTION <br />3.01 General <br />A. Clearing and Grubbing <br />Channel bottoms and side slopes to be protected by riprap shall be free of <br />brush, trees, stumps and other objectionable materiel and be dressed to a <br />smooth surface. All soft or spongy material shall be removed to the depth <br />shown on the plans or as directed by the Engineer and replaced with <br />approved material. Filled areas shall be compacted as specified in Section <br />02200. <br />B. All types of riprap shall be placed on a filter media as stipulated in Sections <br />2.04 and 2.05 above unless otherwise noted on the plans or in the Special <br />Conditions or if it is determined that the natural soil along the channel <br />slopes and bottom meets the requirements of a filter blanket. This <br />determination will be made by the Engineer. <br />• <br />3.02 Placement of Riprap <br />A. General <br />02540-7 <br />