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78-67, Runoff Control Structures <br />Response to Comments <br />page 2 <br />• <br />The currant design would impound water between the two pipes once the lower pipe inlet is buried with sediment, and <br />between the upper and open pillway channel once the upperpipe inlet is buried. A properly slotted riserpipe extended <br />from the lower discharge pipe up to the open spillway elevation may be suficient to properly dewater the structure within <br />24 hours, throughout the life of the structure. Please revise the designs for the nirnoffcontrol structures <br />and incorporate a slotted nserpipe or alternative design that will drain all storage within 24 <br />hours throughout the life of the structure. <br />Further, please amend the permit text in Tab 20 page 18, to include a statement that these <br />,runoff control structures are not intended to impound water, and will be constructed and <br />maintained to drain all storage within 24 hours. <br />Response: A slotted riser has been added to each discharge pipe in the design per the DRMS request. See <br />Figure 20-2, Typical Runoff Control Structure. <br />Attached is information regarding the potential additions to the typical runoff control structure design. If <br />there are any comments or questions, please contact me at (970)276-5217 or (970) 846-3648. <br />Sincerely, <br />• Roy Kano <br />Reclamation Manager <br />GG i?LG?' <br />en" closure(s) <br />cc: Carl Johnston (CISMRE) <br />John Husband (BLM) <br />Sandy Brown (DRMS-Denver) <br />• <br />Seneca Coal Company . P.O. Box 670 • Hayden, Colorado 81639 <br />Telephone (970) 276-5219 • FAX (970) 276-5222