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containment structure during initial pit development. The in-pit <br />structure/ramp material was obtained by removing overburden above <br />one of the Y seam splits. <br />Second, structure #3 was another in-pit structure constructed <br />upgradient of structure #2. Structure #3 would remain only a short <br />time as it would be removed by blasting in 1994 and the early <br />shovel cuts but would provide, during the interim, sediment <br />control. <br />After reviewing the CDMG regulations for guidance as to <br />permitting in-pit structures #2 and #3, we found that by definition <br />Rule 1.04(64) excludes active mining pit areas when addressing <br />impoundments. In addition, with respect to structure #2 which is <br />also associated with the in-pit ramp, Rule 1.04 (iii) similarly <br />excludes such structures from regulation. <br />Also, in a previous conversation concerning another Colowyo <br />subject, Mr. Steve Renner, the Division's previous Coal Supervisor, <br />was asked specifically at what point in time did "mining <br />activities" technically begin and topsoil activities end? Mr. <br />Renner indicated that after topsoil is removed in the pit areas, <br />all subsequent activities such as ramps, drill benches, ditches, <br />etc. are considered mining related and therefore outside of review <br />by the Division. <br />With Mr. Renner's comments and the regulations in mind, <br />Colowyo nevertheless, still intended to protect the environment and <br />meet the "124 acre" requirement by applying appropriate mining <br />techniques and incorporating in-pit structures #2 and #3 into pit <br />development. However, because of the guidance from Mr. Renner and <br />clear indication that CDMG rules exempted these structures from <br />further regulation, no additional permitting was pursued by <br />Colowyo. <br />West Pit Sediment and Runoff Control Practices <br />As described above Colowyo applied in-pit mining practices to <br />provide for additional sediment and runoff control to insure that <br />no more than 124 acres (134 acres with the as-built pond being <br />bigger than design) would contribute runoff and sediment to the <br />West Pit Pond. <br />Please find the attached engineering certifications <br />summarizing the drainage analysis during West Pit development. <br />1) On July 22, 1994, Mr. Steven Hinkemeyer certified <br />information concerning a West Pit drainage analysis that <br />as of July 18, 1994: <br />a) Colowyo was draining only 83.7 acres of the <br />allotted 124 acres to the West Pit Pond. <br />b) For the entire West Pit development area 29.0 acre- <br />feet of storage was required for a 10 year, 24 hour <br />precipitation event (from TR-27) and 68.8 acre-feet <br />