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Here are my comments and questions: 1. Powderhorn Coal Company (PCC) should address inlet protection for Pond 10 where the new 30" CMP will convey runoff from the East Collection Ditch of CRDA 2. 2. PCC should reassess the efficiency of Pond 10 with the additional inlet (30" CMP from East Collection Ditch). It would appear that this relocation may result in short circuiting the pond. 3. Will the ditches on Access Road 9 be sized for runoff upgradient (southeast) of the road? PCC should give us this information, including details of the ditch size. 4. PCC states that drainage from the Access Road 9 ditches will continue to the Access Road 3B ditches. Are the ditches on 3B large enough to carry the additional flow? PCC should provide additional information to demonstrate that the ditches are capable of carrying the additional flow, or include plans to enlarge the 3B ditches. 5. PCC should designate the location of the 30" CMP on Access Road 9 on Exhibit 52 or 9C. It does not appear that they have given its location. 6. PCC needs to address sediment contribution from CBA 1 and allow for additional storage capacity in the sump. 7. PCC needs to make some sort of commitment to cleaning out the pond and dewatering the sump at a certain level and/or installing indicators of maximum sediment and water levels that can be reached while maintaining the storage capacity for the 10 year - 24 hour and 25 year - 24 hour storm events. 8. PCC needs to address sediment control on the east side of the reconstructed Coal Gulch Channel. PCC states that the channel bottom will be lined (20' wide) with rip rap. That leaves a disturbed area roughly 100' wide and 800' long that will not have sediment control. 9. PCC states that the particle size distribution used to model sedimentology at Pond 11 is from soil samples taken at CBA 2. The particle size distribution should be of that which would reach the sediment pond, ie: those particles which would be entrained in the event of runoff. PCC should revise the distribution accordingly for runoff from both CBA 2 and CRDA 3. 10. In modelling Pond 11, PCC used 11.32 acres for the CBA 2 watershed. For the East Collection ditch, the watershed acreage used is 7.5 acres. Why is there a difference in values used for the two models? 11. The proposal includes relocation of Pond 11 approximately 500 feet east of its previously approved location. PCC needs to obtain approval from CDOH-WQCD to move the NPDES outfall at Pond 11, and provide a copy of that approval to us. rtca rosy 2 e ruary 4, 1 4