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Colowyo, C3981 -019, PR3 adequacy No. 3 <br />July 22, 2011 <br />CCC provided the Division a copy of CDOW's letter, dated May 17, 2011. Please address <br />CDOW's concerns and recommendations in the proposed permit text. This item remains <br />inadequate. <br />This item has been resolved with the August 9, 2011 submittal. <br />Rule 2.05.6(3)(a) Protection of the Hydrologic Balance <br />1. The application contains limited permit text narrative with regard to impacts to registered <br />ground water users due to pit dewatering and development and is deficient with regard to <br />impacts to ground water users (see discussion above under Rule 2.04.7(3)). Please expand the <br />permit text narrative under the section discussing probable hydrologic consequences to ground <br />water quantity, with particular emphasis on discussion of impacts to wells owned by others. <br />In order to recognize that most postmining spoil leachate seepage into the downdip pitwall <br />probably will occur in the more permeable beds (the coal seams and cleaner sandstone beds), <br />please use in the pitwall seepage calculation for the Collom Lite Pit a value for K that is within <br />the range of most values for the coal seams and sandstone beds (for example, 0.01 ft/day, rather <br />than the 0.0001 ft/day in the submittal). Also, please use in the calculation of the cross - <br />sectional area of the downdip pitwall only the aggregate net thickness of sandstone and coal <br />beds (that is, exclude the shale and siltstone beds from the measurement of the pitwall height <br />because those beds are not capable of transmitting a significant amount of spoil leachate). The <br />aggregate net thickness can be measured on a geophysical log. <br />Please refer to question 2.04.7(3) abuvc under the heading Alternative Water Supply. <br />As previously requested in our letter of July 22, 2011 under this section (and in 2.04.7(3)), <br />please add to the application a quantitative estimate of the cone of depression from Collom Lite <br />Pit dewatering. <br />3. As mentioned previously, the plan for control of surface water drainage through the disturbed <br />area is deficient at this time due to uncertainty of the proposed mine plan and the long -term <br />presence of the temporary spoil pile in the center of the disturbed area. The application does <br />not adequately present how surface water will be handled over the life of the operation (Rule <br />2.05.6(3)(b)(i)). <br />The response is inadequate. The application does not adequately present how surface water <br />will be handled over the life of the operation (Rule 2.05.6(3)(b)(i)). The Division cannot defer <br />sediment control issues to a later date unless CCC is requesting only limited mine plan <br />approval for the Collom Lite and Little Collom X areas. The Division understands the worst <br />case scenario for hydrology and sedimentology and has specific questions related to that review <br />later in this letter. CCC states in response to this question, "Later stages in the mine <br />progression will be reviewed in more detail..." That detail is required for all areas within the <br />Collom proposed permit area in the current revision application (PR -03). Please refer to the <br />original question. <br />