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RULE 2 PERMITS <br />the need for permitting of coal mining operations, and the desire to be a responsible steward of the <br />land, the company could select to manage lands in a manner similar to other Western ranching <br />operations that emphasize red meat production from livestock with little concern for the needs of <br />wildlife. <br />Protection of Hvdrolo2ic Balance and Water Quali <br />Based on the data, other references available and reclamation plans previously presented in this <br />section, the Colowyo Mine will not adversely affect the hydrologic balance or water quality of the <br />adjacent areas. <br />The Colowyo Coal Company intends to use all practical methods to maintain the hydrologic balance <br />and water quality in its present state and may improve the surface water characteristics as a result of <br />reclamation procedures. The focus of this discussion will center on the permit area as it is the area of <br />mining disturbance. <br />The hydrologic balance, previously discussed, will be protected through a number of procedures <br />designed to mitigate any potential impact from mining. Temporary and permanent diversions will <br />route runoff away from disturbed areas to minimize erosion and sediment loss. Temporary channels <br />are designed to safely pass the runoff from a 10 -year, 24 -hour precipitation event and, where <br />necessary, will be constructed using bank stabilization methods including energy dissipators, <br />sediment traps, and dug outs or a combination of these methods. Drainage culverts will also use <br />energy dissipators at the outlets if necessary so that runoff will not cause additional erosion and <br />subsequently increased total suspended solids (TSS) levels. Detention ponds will be used to detain <br />runoff water from the disturbed areas to allow the TSS to settle out and to attain acceptable <br />concentrations for other parameters consistent with the requirements of the NPDES Permit. Any <br />Small Area Exemptions (SAE'S) employed will be designed to minimize contributions of TSS to the <br />hydrologic balance. <br />Infiltration and percolation of precipitation in the mine area may be enhanced by the reclamation <br />techniques of contour furrowing on hillsides and the continued excellent revegetation success at <br />Colowyo. Infiltration rates for the pre -mined and post -mine condition of the land were presented <br />earlier. Striffler and Rhodes (1981) showed through field measurements, using an intense rainfall <br />simulation, that infiltration capacities of the mulched and revegetated areas were much greater than <br />the pre -mine estimates. Runoff from the revegetated and contour - furrowed areas has been minor to <br />date, as documented by Colowyo Mine personnel. Flows from Streeter Gulch will be moderated with <br />the detention pond. <br />Moderated flows will continue to pass through the historic drainages. Recharge of the limited <br />groundwater systems in the mine will not be inhibited and may be enhanced through the use of the <br />above techniques. <br />Groundwater protection, per se, is not necessary in the permit area as essentially no continuous <br />groundwater system exists. Perched aquifers of limited nature will be impacted only in the mine area <br />property. This water will be evaporated. The quantity of groundwater is minimal as evidenced by the <br />lack of water in test holes and the dry active pit. <br />Rule 2 Permits 2.05 -50 Revision Date: 6/11/12 <br />Revision No.: RN -06 <br />