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in place after reclamation of the Scullion Gulch diversion pipe since the pond was constructed on top of <br />the diversion pipe and will be destroyed when the diversion is removed. Sediment control during <br />reclamation of this area is discussed further in Section V.B.6. <br />The mine operator will monitor the natural drainage system over and in the immediate vicinity of the <br />underground mine. <br />Should subsidence occur which affects this natural drainage pattern, the operator will advise the <br />appropriate regulatory agencies who will decide whether or not the disturbance is significant enough to <br />require that a sedimentation and drainage control system be installed. In such a case, the system will <br />adhere to all regulatory requirements. <br />Rock check dams were also constructed east of the railroad loadout loop as an alternate means of <br />controlling sediment. With the addition of the two ponds on the south side of the railroad fill slope, these <br />rock check dams serve a backup purpose. <br />IV.J.4 Life of Mine Diversions Disturbance to natural drainage channels has been avoided wherever <br />possible. However, to provide enough level space without undue terrain disturbance, the grading plan <br />for the "D" Portal Area required rerouting of the main Scullion Gulch drainage channel through a large <br />diameter pipe culvert and of a tributary to Scullion Gulch northwest of the raw coal silo pad through a <br />pipe culvert. The main Scullion Gulch diversion is approximately 2,750 feet long and the tributary <br />diversion is approximately 312 feet long. The grading plan for the East Portal entry did not require <br />rerouting of Scullion Gulch. The Scullion Gulch diversion was designed in accordance with 30 CFR <br />Section 817.44 requirements for permanent diversion of intermittent streams as the stream has <br />watersheds in excess of one square mile. The requirements for permanent diversions were adhered to <br />due to the expected long life of the mine. The diversion of Scullion Gulch at the "D" Portal Area was <br />constructed at the start of grading operations. It will be regularly inspected and maintained during mine <br />operation. Details of the diversion design are presented in the Reclamation Plan. The layout and profile <br />of the diversion is presented in Maps 29, 30 and 31. Calculations are included in Illustration 9. Maps 21 <br />and 23 show the drainage areas for this diversion. The existing channel, plan, profile and cross-sections <br />are shown on Maps 36, 37, 38 and 39. The stream diversions at the "D" Portal Area will be removed at <br />the end of active mine operations and the stream channel will be returned (approximately) to its original <br />meandering path and gradient as shown on Maps 40, 41 and 42. <br />Rev. TR-53 (01!2001) IV-41 <br />