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I. INTRODUCTION <br />n <br />LJ <br />This report has been prepared as supporting documentation for removal of certain <br />sediment control measures at specific locations within the Lone Pine Gulch Surface <br />Facilities Area and the Water Tank Site at the Mountain Coal Company (MCC) West <br />Elk Mine (Colorado Division of Minerals and Geology permit C-80-007). Currently, <br />the mine has sediment control measures (silt fence) installed below the Underground <br />Development Waste Pile (UDWP), the Topsoil Pile, and the Staging Area at the Lone <br />Pine Gulch Surface Facilities Area. Silt fence has also been installed and maintained <br />below the Water Tank on a hillslope above the main West Elk Mine site. After <br />construction of the above facilities and structures, MCC seeded each area with the <br />approved reclamation seed mix to stabilize each area. Silt fence was installed at each <br />location to prevent sediment laden runoff from leaving the disturbed area. At this time, <br />MCC wishes to evaluate the potential for surface erosion from each area, and <br />determine whether removal of the silt fence would be justified from an erosion and <br />sediment control standpoint. Documented within is information relative to the erosion <br />and sedimentation condition of these reclaimed or revegetated areas, and the adjacent <br />native vegetation communities adjacent to each of the areas discussed. Quantitative <br />sampling of vegetation was performed in July and August 1997, utilizing methods <br />approved by the Colorado Division of Minerals and Geology. Results of the <br />• quantitative vegetation sampling aze presented in the appendix following this report. <br />Sedimentation and erosion analysis was conducted by Mr. Michael Savage of Savage <br />and Savage. <br />II. METHODS <br />SEDIl1~fENTOLOGY DEMONSTRATION <br />The reclaimed and revegetated areas are shown on Figures I and 2 of the appendix. <br />Reclaimed or revegetated areas must be shown to contribute equal or less sediment than <br />adjacent undisturbed areas to the receiving waters downstream in order to satisfy one of <br />the requirements for removal of sediment control measures. There are several methods <br />by which to compare sediment generation from disturbed and undisturbed sites. <br />Historically, CDMG has used a model (SEDCAD+) to evaluate similar or identical <br />watershed sections within the reclaimed area and adjacent undisturbed area. There are <br />limitations to this approach, as there are rarely identical adjacent watersheds. Further, <br />exact knowledge of all of the parameter values for the areas to be compared is often not <br />available. Given the relatively small size of the disturbances to be evaluated at the <br />West Elk Mine, we elected to compare sediment generation from the reclaimed and <br />• <br />-I- <br /> <br />