2008-03-20_GENERAL DOCUMENTS - C1981019

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pit is reclaimed. It also assumes that during mining operations when a large pit is in-place, that much of the storm water runoff is captured by the pit. This presumption was accepted by the Division given that both Streeter and Gulch A watersheds reflected this practice (see 2006 ARR Map). The Prospect pond, as currently approved, also assumes a worst case condition, with four varieties of land condition; reclaimed 3 or more years vegetation growth, reclaimed 1-2 years vegetation growth, lands topsoiled and seeded with no significant vegetation, and undisturbed lands. The latest pond modeling was revised and approved in 2002 for the Prospect pond. Calculated peak discharge from the modeling resulted in 2.33 cfs with a total runoff volume of 1.95 ac-ft. There is a long and lengthy written record of the debate between Colowyo and the Division concerning the modeling and sizing of this pond. Ultimately, the Division approved this pond, and subsequent revisions, primarily because of Colowyo's commitment that the actual reclamation on-fhe-ground would closely mimic the assumptions used in the modeling. Conversely, if actual conditions do not, then the logical conclusion would be that the pond will likely not function as designed. The current problem lies in the fact that approximately 320 acres of land in pit, ungraded spoil and spoil ridges, and final grade 8 & G lies directly above the Prospect pond. Again, Colowyo is rapidly completing all backfilling and grading of the East Pit with a dragline and dozers. If all of the approximately 320 acres are regraded to final grade, the actual field conditions will massively exceed the hydrologic modeling assumptions in a negative way. This could have catastrophic impacts to the lands below, including State Highway 13. There is almost no chance that Colowyo can reclaim the Prospect watershed to a condition even reasonably close to the hydrologic design assumptions anytime in the next two years without a significant change in their reclamation pace and practices. For example, last year they completed 86 acres of 8 & G, topsoiled zero acres, and reseeded 20 acres. At this rate, the East Pit will be at final grade as early as late 2007, leaving hundreds of acres of regraded spoil with no topsoil or vegetation. In my opinion, given fhe current on-the-ground conditions and conditions in the near future, even a small, intense storm event than a 10-year recurrent interval (1.8 inches/24 hours) could have devastating consequences. Additionally, Prospect drainage requires a channel lining of riprap, yet currently sits at final grade without riprap protection. This could lead to channel erosion and gullies, producing sediment in a quantity that would rapidly fill and overwhelm the Prospect pond, leading to water quality concerns at a minimum and/or pond failure in a worse scenario. • The Division must require that channel lining is established rapidly during and immediately after final grade is achieved. Colowyo established riprap over a long length of the Prospect ditch in 2007. However, the lower section of the ditch is not riprapped, possibly at the point where water leaves to enter the unreclaimed pit, or sump, down to the joining of the undisturbed channel above the pond. Having this amount of regraded spoil draining to a single sediment pond is unprecedented at Colowyo. There is no site-specific past experience that comes close to the scenario that is developing. Furthermore, as stated above and documented in the approved permif, the Prospect pond was not designed for the conditions that currently exist in the watershed.