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Name of Addressee <br />Page 2 <br />Date <br />channel does not reflect the worst case scenario of the land condition contributing to the drainage <br />channel at the time of construction. By utilizing an average curve number which includes one third of the <br />watershed to be at 2 years growth is assuming that would be the case even if 100% of the watershed is <br />freshly topsoiled. If it is Trapper's intention to utilize a generic design for all drainage channels, the <br />Division's believes that a curve number used in the design of the generic model should not reflect an <br />assumed land condition that may or may not be the worst case scenario. Please provide update designs <br />for the proposed postmining drainage channels to include the worst case scenario for the construction of <br />the drainage channels. In addition, the SEDCAD models do not include a variable for 0.3 feet of freeboard <br />as required under Rule 4.05.3(7)(b). <br />