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~~. <br />EXHIBIT 13 <br />SEDIMENTATION PONDS - <br />HYDROLOGIC INVESTIGATIONS <br />~~^--. <br />e <br />INTRODUCTION <br />Energy Fuels Corporation (EFC) proposes a total of 18 sedimentation ponds, <br />designated A through T except I and J, which have been designed to bring <br />the existing and proposed mining areas into compliance with the newly <br />issued Office of Surface Mining (OSM) regulations. The ponds are loc- <br />ated schematically on Energy Mines No. 1 and 2 Hydrology (EFC Map 13), and <br />Eckman Park hydrology (EFC flap 14). In accordance with 30CFR816.46 (c), <br />the ponds are desinged to detain the inflow from runoff produced as the <br />result of the 10-year 24-hour duration precipitation event to allow removal <br />of sediment particles. Pond A is also designed to store 27 acre-feet of <br />irrigation water. <br />This report describes the hydrologic investigation and the hydraulic design <br />for the 18 ponds which have been undertaken by Leonard Rice Consulting Water <br />Engineers, Inc. (LRCWE). Base mapping having a scale of one inch to 500 <br />feet and a contour interval of 10-feet was provided by EFC. A soils and <br />geotechnical study has also been performed by CTL/Thompson, Inc. <br />HYDROLOGY <br />Rainfall <br />Rainfall information for the State of Colorado is published by the National <br />Weather Service in a volume titled NOAA Atlas 2, Precipitation-Frequent <br />Atlas of the Western United States, Volume 3-Colorado. The publication con- <br />tains maps giving total rainfall depths for the 2 through 100-year frequen- <br />cies and the 6-hour and 24-hour durations. For the 24-hour duration, the <br />10-year rainfall total is 1.8 inches, the 25-year total is 2.1 inches, and <br />the 100-year total is 2.70 inches. For the Sedimentation Pond A site only, <br />Leonard Rice Consulting Water Engineers. Inc. <br />