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Kathy Welt <br />March 19, 2010 <br />Page 2 <br />Facilities Area. <br />Response: Mountain Coal Company will respond to this comment. <br />4. CDRMS Comment: Will the clean water ditches drain to the sediment control ponds as <br />shown on Map 54C? <br />Response: Mountain Coal Company will respond to this comment. <br />5. CDRMS Comment: Please explain how the maximum pitch grade limit of 15 percent [Rule <br />4.03.1(3)(a)(iii)] will not be exceeded, given the steep grades shown for haul road <br />switchbacks on Map 53. <br />Response: As indicated in Section 4.7.1 of the permit application and shown in the <br />profiles on Drawings C-10 and C-11 for Haul Roads 1 through 4, typical design grade of <br />the haul roads is 8 percent while the maximum grade was kept to 10 percent. All design <br />grades for haul roads on and off the refuse pile comply with the requirements of Rule <br />4.03.1(3)(a), including the requirement that a maximum pitch grade of 15 percent not be <br />exceeded. <br />6. CDRMS Comment: Please add a table to Exhibit 82 showing culvert design information for <br />the haul road culverts. <br />Response: Based on additional hydrologic and hydraulic modeling of drainage from <br />undisturbed areas conducted after the January 8, 2010 submittal, it was determined that <br />the drainage could be safely routed along the existing and proposed roads and no <br />culverts would be required. Drawing C-13, Overall Drainage Plan, has been updated to <br />show the revised drainage design, with drainage flow arrows added to indicate the <br />proposed surface water runoff routing. <br />7. CDRMS Comment: To facilitate preparation of the reclamation cost estimate, please <br />provide a table that lists all structures, including their dimensions and materials. Also, <br />include any significant regrade volumes for the haul roads. <br />Response: A table listing volumes and areas for use by CDRMS in estimating the final <br />reclamation costs for the project is attached. We'd like to point out that there are no <br />culverts on the haul road and clear water diversion ditches. Also note that the sediment <br />pipes and manholes constructed to control and direct the runoff and underdrain flows to <br />the RPE ponds are permanent structures and will remain at fmal reclamation. <br />8. CDRMS Comment: Please resolve the apparent discrepancy between Drawing C-15 (which <br />shows sediment pipes next to the refuse pile) and Section 3.2 and the SEDCAD runs (which <br />mention ditches for sediment control next to the refuse pile). <br />P:\Mpls\06 CO\26\06261003 MCC Refuse Pile Site Review & Permit\WorkFiles\Permit Application\Response to Comments\2010-02-10\Response <br />Submittal Documents\2010-03-19 Barr Response Letter.doc