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Riprap Notes <br /> 1 Riprap bedding shall be a porous free draining material consisting of sand, gravel, crushed stone or <br /> other approved free draining material. This material shall meet the following gradation requirements: <br /> GRADATION FOR GRANULAR BEDDING <br /> b "Weight_Passing <br /> Sieve Size Type II <br /> CDOT Sect.703.09 Class A <br /> 3 inch 90— 100 <br /> 1-1/2 inch ---- <br /> 3/4 inch 20-90 <br /> 3/8 inch ---- <br /> #4 0—20 <br /> #16 ---- <br /> #50 ---- <br /> #100 ---- <br /> #200 0 -3 <br /> 2 Riprap bedding shall be imported. <br /> 3 Riprap stone shall be rough,fractured, and have a specific gravity of at least 2.65. <br /> 4 Riprap shall consist of individual angular rock fragments which shall be dense. hard, sound, and <br /> resistant to abrasion; shall be free from cracks, seams, and other defects that would tend to unduly <br /> increase their destruction by water and frost actions. <br /> 5 Riprap stones shall be nearly cubical as possible,with neither breadth nor thickness of a single stone <br /> less than one-third of its length Thus, slab type stones,flaking rock, rounded stones, asphalt. broken <br /> concrete, concrete slabs, or other materials not classified as rock will not be allowed for use as riprap <br /> material. <br /> 6 Riprap shall be clean,free of fines,and shall meet the following re uirements <br /> % Smaller Than Given <br /> Size by Weight Type L Riprap <br /> d50=9inches <br /> 70-100 15 <br /> S0-70 � 12 <br /> 35-50 9 <br /> 2-10 1 3 <br /> 7 Riprap bedding shall be placed uniformly to the grades and elevations shown on the Construction <br /> Plans. Care shall be taken to keep the bedding thickness uniform. Excessive rutting of the finished <br /> bedding surface shall be avoided. Riprap bedding shall be kept clean and free of other soils. <br /> 8 Riprap shall be placed in such a manner so as not to cause a segregation of particle saes. Placing in <br /> layers or by dumping into chutes or similar methods that may cause segregation are specifically <br /> prohibited. <br /> 9 Riprap shall be placed to grade in a manner to ensure that the larger rock fragments are uniformly <br /> distributed and the smaller rock fragments serve to fill the spaces between the larger rock fragments <br /> in such a manner as will result in a well-keyed, densely placed, uniform layer of riprap of the specified <br /> thickness. Consolidation of the riprap by backhoe or other means will be necessary to insure <br /> interlocking of rock fragments. Placed riprap shall be uniform and free from bulges, humps, or <br /> cavities. Hand placing will be required only to the extent necessary to secure the results specified <br /> above <br /> 10. Riprap was empirically sized using a design for a similar upstream project recently completed for the <br /> City of Boulder Open Space and Mountain Parks Hydraulic modeling was completed for the <br /> previous upstream project,and riprap was designed based on U.S. Department of Transportation <br /> Federal Highway Administration HEC-23 Design of Riprap for Overtopping Flow. A similar detailed <br /> design was not completed for the ERTL project. Applegate Group believes the riprap will provide <br /> adequate protection from future breaches based on similar flows at the previous upstream project, but <br /> cannot guarantee the riprap size will be appropriate for all potential future high flows. <br />