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RULE 2 PERMITS <br /> <br />Rule 2 Permits 2.05-36 Revision Date: 8/6/25 <br /> Revision No.: PR-05 <br />levels, or perhaps return to elevated levels as has been experienced at certain Wyoming mining <br />operations. <br /> <br />Related to this mitigation and emphasis on wildlife populations, focus must be maintained on the <br />fact that Colowyo is the landowner on the overwhelming majority of disturbed acreage. Were it <br />not for the need for permitting of coal mining operations, and the desire to be a responsible steward <br />of the land, the company could select to manage lands in a manner similar to other Western <br />ranching operations that emphasize red meat production from livestock with little concern for the <br />needs of wildlife. <br /> <br />Protection of Hydrologic Balance and Water Quality <br /> <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 /> <br />The Colowyo Coal Company intends to use all practical methods to maintain the hydrologic <br />balance and water quality in its present state and may improve the surface water characteristics as <br />a result of reclamation procedures. The focus of this discussion will center on the permit area as it <br />is the area of mining disturbance. <br /> <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 <br />channels are designed to safely pass the runoff from a 10-year, 24-hour precipitation event and, <br />where necessary, will be constructed using bank stabilization methods including energy <br />dissipators, sediment traps, and dug outs or a combination of these methods. Drainage culverts will <br />also use energy dissipators at the outlets if necessary so that runoff will not cause additional erosion <br />and subsequently increased total suspended solids (TSS) levels. Detention ponds will be used to <br />detain 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 <br />the hydrologic balance. <br /> <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 <br />than the pre-mine estimates. Runoff from the revegetated and contour-furrowed areas has been <br />minor to date, as documented by Colowyo Mine personnel. Flows from Streeter Gulch will be <br />moderated with the detention pond. <br /> <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.