2013-11-07_PERMIT FILE - M2013070

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Liberty Mining, LLC DRMS 110 -d Permit Application October 2013 U (10) Surface Water Control and Containment Facilities Information The Liberty Mine, formerly the South October Mine, is located in west central Colorado, in Mesa County. The mine is situated south and west of Grand Junction, Colorado at an elevation of approximately 6900 feet above mean sea level. The mine site is located above and west of the Dolores River and Colorado State Highway 141. The general terrain of the area is described as relatively steep surface slopes ranging from nearly vertical rock outcrop cliffs to boulder strewn slopes of 5 to 40 percent with medium to sparse pinon- juniper tree cover, sparse natural grasses, and other low vegetation. The specific site of the Liberty Mine is located above nearly vertical slopes of rock cliffs in an area with surface slopes ranging from 12 to 17 percent. The area surface has a great many boulders, the pinon- juniper community, and a sparse covering of natural grass. See photos on the following pages. From the National Cooperative Soil Survey, as provided by the Natural Resources Conservation Service of the USDA, the Hydrologic Soil Group for the mine site is classified as a "C ", being described as "Bodot- Silt -Rock outcrop complex, 5 to 25 percent slopes, very bouldery'. A portion of the site is classified as a "D" soil group, described as "rock outcrop, 50 to 99 percent slopes ". The area described as 50 to 99 percent slopes is located to the east of the mine site and does not represent the area influencing drainage for the mine site. The mine site consists of soil with a class /rating of C, used in the drainage analysis. The Group C soil classification is described as soils having a slow infiltration rate when thoroughly wet. These soils are characterized as having a layer that impedes the downward movement of water or soils of moderately fine or fine texture, with a slow rate of water transmission. Rainfall data for the area was obtained from the NOAA Atlas 2, Volume 3, prepared by the U.S. Department of Commerce National Oceanic and Atmospheric Administration National Weather Service, office of Hydrology for the U.S. Department of Agricultural Soil Conservation Service, Engineering Division. Analysis Approach Analyses for determining the storm water impacts to the mine site were based on the Rational Method for determining the runoff rates and the peak runoff, and the Simplified Peak Flow method for determining the runoff volumes for sizing retention /detention ponds. The procedures for employing these methods were based on Section 600 - Rainfall of Mesa County Stormwater Management Manual. In completing the stormwater analysis, the project was divided into two segments (see Exhibit 1, Drainage Basin Delineation). The first segment determined the impacts to, and the need for improvements necessary to manage stormwater runoff on and /or from the entrance road. The second segment determined the impacts to and the need for improvements necessary to manage of stormwater on the mines operation site. The first segment, i.e. determining the impacts of stormwater flows on the roadway, was contingent on the current grading of the roadway remaining unchanged. It was assumed that the roadway shape and grading would not be altered to the degree that the drainage flow paths would be changed from those currently established. With this assumption, the roadway shape and /or grading, i.e. whether crowned or cross - sloped, will result in drainage water being directed to a drainage swale or ditch between the roadway and the uphill slope, reducing water being allowed to sheet flow across the roadway. Exhibit U1 and 2 depict the drainage areas, or sub - basins, used in determining the contribution of runoff to the roadway and to the operational site. Liberty Mining; LLC Moab.. Utah SMA Ref. 5821897 Page 60