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area, to ensure that it will conform with the approved design and the SEDCAD <br />modeling. Additionally, the Division also requested that Colowyo provide a more <br />detailed description of any alternate sediment control measures that it will use in <br />the East Pit reclamation and give the Division a higher level of confidence with <br />regards to the Prospect drainage and the Prospect Pond. <br />Current modeling of the Prospect watershed includes ONLY disturbed acres, <br />which, in the worst hydrologic condition, are topsoiled and seeded. In other <br />words, modeling includes no areas of regraded spoil or topsoil that has not been <br />seeded. This is significant for the following reason. Colowyo regraded 86 acres in <br />2006 and topsoiled those same acres in 2007. They completed no backfilling and <br />grading to final grade in 2007 in the East Pit (see 2007 ARR). Therefore, <br />according to the currently approved modeling and pond design, Colowyo must <br />topsoil and see all acres backfiilled and graded in the same field season. There are <br />about 281 acres remaining in the Prospect watershed to return to final grade, <br />topsoil and see. <br />Furthermore, Colowyo is currently sumping runoff from reclaimed areas to the pit <br />or partial pit, as the case may be. This obviously helps prevent issues at the <br />Prospect pond and beyond but this practice also raises questions about design <br />criteria, maintenance and impoundment questions relative to the ditches and <br />sump. If Colowyo does, in fact, plan on using this sumping method to control <br />runoff from both the disturbed and reclaimed areas of the Prospect drainage, this <br />needs to be explicitly stated and the necessary hydrologic designs must be <br />provided to the Division. If the Division does not have design information for a <br />ditch/sump system that fails, there is no way to ensure that the system was <br />constructed and/or maintained to any required standard or design. <br />Please provide the Division with a detailed schedule for the backfilling and <br />grading of the east Pit up to and including final pit closure. Please include a map, <br />or plate and acreages of each regraded area, to ensure that it will conform to the <br />approved design and the SEDCAD modeling. As part of this schedule the Division <br />also requested that Colowyo provide a more detailed description of any alternate <br />sediment control measures that it will use in the East Pit reclamation, including <br />surface roughening techniques for the areas that have been recently topsoiled. <br />Additionally, please provide detailed information regarding the sumped and <br />diversion of Prospect runoff into the East Pit, including the hydrologic condition <br />for those areas diverted, sump location, sump size and ditch configuration, <br />location and sizing. <br />Response: Due to the many concerns voiced by the Division regarding this matter, Colowyo <br />voluntarily discontinued plans to move forward with reclamation activities in the East <br />Colowyo Mine • 5731 State Highway 13 • Meeker, Colorado 81641 <br />T +1 970 824 1500 • F +1 970 824 1504 9 www.rtea.com