2011-05-23_REVISION - C1981019 (2)

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Colowyo Response - PR3 adequacy No. 2 12 May 6, 2011 able to identify only two other remaining areas that do not report to the sediment pond system and would therefore require special sediment control treatment. These are the southernmost 11 acres of the plant site area in Section 36 after it has been regraded back to pre-mining topography, and an approximately 0.5 acre area in Section 34 that is just outside the D7D8 ditch. These conditions will not be encountered until late in the mining operation, and if they cannot be redesigned to avoid this concern, Small Area Exemptions or alternative individual sediment control systems will be requested. With regard to management of waters intercepted by the spoil pile that blocks the valley, the short answer is that these waters will be pumped up to the perimeter ditches around the spoil pile, and will ultimately report to the sediment pond system. Exhibit 7, Item 23, Figure A2 has been included in the revised Exhibit 7, Item 23 Part A. It shows a perimeter ditch that collects all runoff from the spoil pile east and west faces and directs that runoff to the sediment pond system. Runoff from the northern face of the growing pile already reports directly to the Collom Sump. Runoff from the southern face of the spoil pile reports to the valley bottom south of the spoil pile and downstream of the active pit. The SEDCAD modeling for the limited (217 acres) area tributary to the valley bottom above the spoil pile indicates that the volume is small enough that it will pond to about 12 feet deep adjacent to the haul road fill in that valley, and the volume is such that it can be pumped up and out to the perimeter ditch around the spoil pile. Under these conditions, runoff from this intermediate area will not report to the sediment pond system during the storm runoff event. The same applies to the runofffrom the upstream reaches of the watershed that is intercepted by the active pit. 0 Rule 2.05.3(6) Overburden 1. Please assure that appropriate detail required by Rule 2.05.3(6) is included in the Operation and Reclamation plan. Discussion of the pit dimensions, swell factor and blasting detail was not found in Section 2.05.3(1) Operation Plan, or Section 2.05.3(6) Overburden of the PR3 application, nor was there a discussion of where this information could be found in the application. Please provide the detail required by Rule 2.05.3(6). Please state which seed mix CCC will employ for temporary overburden stockpile stabilization (Collom-Rule 2, page 99). Colowyo 's Response: Colowyo provided additional detail in Section 2.05.3 (1) as to swell factor and blasting as requested. Information describing the overall pit dimensions of the Collom Lite and Little Collom X pits was provided in Section 2.05.3(1). References have been added in the text of Section 2.05.3(1) to reference the appropriate location of blasting details applicable to the Collom expansion area activities. The seed mix to be applied to inactive portions of the temporary spoil pile has been included in the text of Section 2.05.3(6). Rule 2.05.4(2)(b) Reclamation Costs and Rule 3 Performance Bond Colowyo Coal Company has not provided a reclamation cost estimate for the Collom expansion area at this time. As mine plan details are finalized, a reclamation cost estimate is required to be submitted and incorporated into the permit.