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Mr. William A. Bear -3- June 22, 1982 <br />• Additional sediment control procedures including, but not limited to, gravelling <br />of the portal bench, grading of the portal bench so that drainage is directed <br />toward the highwall and not over the surface of the bench, vegetative stabili- <br />zation where practical, and a regular schedule for clean up of coal spilled <br />beneath the conveyor at the mine bench should be addressed. <br />Ditches: <br />Two problems were noted with ditch designs; high flow velocities and lack of <br />freeboard in the design. The size of rock riprap for Ditches A and B should <br />be specified. A D50 of at least 6" is necessary for Ditch B. Also, ditch <br />designs should be revised to incorporate at least 0.3 ft. of freeboard as <br />required by Ruie 4.05.3(6)(b). <br />Stipulation No. 2 <br />The response to the potential flooding issue refers to the flood protection <br />afforded by Paonia Reservoir and the minimization of flood potential which <br />will be achieved as a result of the Xighway Department's relocation. The <br />response states that "special attention will be given to reconstructing the <br />channel so that flood potential is minimized or completely e_'iminated." <br />The effects of the channel relocation on flooding (i.e., the flood event that <br />would be contained within the banks of the channelized river) should be <br />explained in more detail. <br />• Stipulation No. 3 <br />The response states that if water is encountered in the workings, it will be <br />routed to a sump and NPDES required parameters will be sampled prior to <br />discharging water to the surface. A plan drawing should be provided which shows <br />the location of the sump(s) in the mine workings and details the design and <br />capacity of the sump(s). The response should specifically explain how water <br />would be routed to and contained within the sumps, given the fact that mining <br />is up-dip and water would naturally drain toward the portals. <br />Stipulation No. 4 <br />She response states that a full year of hydrologic data wilt be submitted in <br />August of 1983. Zt should be noted that the annual report required by the <br />stipulation is to be submitted each year of the permit term. <br />Stipulation No. 5 <br />~'he response satisfies the requirements of the stipulation. <br />Stipulation No. 6 <br />Again, it is noted that the annual report is to be submitted each year of the <br />permit term. <br />i <br /> <br />