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o <br /> Z'13 Colorc_do —ve. <br /> GIE3,.roccI CO 81COl <br /> September 27, 1991 <br /> Dan Mathews <br /> mined Land Reclamation Division <br /> 1313 Sherman <br /> Room 215 <br /> Denver, CO 80209 <br /> RE: TR-18. Response to Joe Dudash' memo of 9/18/91 <br /> Dear Mr. Mathews: <br /> In Joe Dudash's memo concerning review of the designs for secondary <br /> spillways Mid-Continent was asked to respond on several points. <br /> Riprap design. <br /> Riprap material shall be of free-draining, durable rock, <br /> varying in size, with the average, D,, = 8 inchas. <br /> Mid-Continent proposes to place a layer of smaller, <br /> gravel to cobble size rock beneath the larger reek: <br /> material . <br /> As indicated in the June 21 submittal , riprap would be <br /> placed to a depth of 1 foot at the bottom and sides of <br /> the spillway channel , down the outside slope of the <br /> embankment. <br /> Mid-Continent proposes placement of riprap material at <br /> all ponds included in this request for revision excert <br /> the load-out pond. Mid-Continent does not believe r4p <br /> rap will be required at the Ioadout pond as it has no <br /> outslope, and is of concrete construction. <br /> Recertification of the ponds on completion of <br /> construction. <br /> 48 1J 1 <br />