2011-08-10_APPLICATION CORRESPONDENCE - C2010088 (2)

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Corey Heaps CAM Colorado LLC August 10, 2011 Page 13 Additional Questions regarding the Access Road 51i. No profile or typical section for the Access Road are shown on Map 15. Please add these details to Map 15. CAM -Please see revised Map -15. Text has been added to page 2.05 -14 to address road surfacing. Division Response: Typical section and profile were added to Map 15, as requested. Text was added to page 2.05 -14 to address surfacing of the access road, but this text (and the thickness shown on Map 15) are in conflict with text already provided on page 2.05- 15. That paragraph states that 6 to 12 inches of gravel will be used. Given the poor quality of native soils at the site, a 6- to 12 -inch thickness is likely to be necessary for surfacing the Access Road. Please revise Map 15 accordingly and delete the contradictory information from page 2.05 -14. 51j—m. Items resolved. Rule 2.05.3(4) Ponds, Impoundments, and Diversions 52 -55. Items resolved. 56. In the submittal dated April 11, 2011, CAM revised the curve number of the wetlands to 74, which is a reasonable value to the Division. However, the April 11, 2011 submittal left out the Sedcad peak discharge data sheet for the west culverts that had been included in the original submittal on page Exh -9 -7. In addition, there are no Sedcad data sheets that show the peak discharge for the designed event for the other culverts on site. Finally, there are no Sedcad designs that show that a culvert of a certain diameter can handle the designed peak discharge for the designed precipitation event. Please provide the appropriate Sedcad data sheets for all of the loadout culverts. CAM - Please see SedCad data sheets showing peak discharge for the requested culverts begin on page EXH. 9 -69 in Appendix 9. The culverts were designed as stated on page EXH 9- 2 which states the 'Culvert size based on Figure 4 -1 S from the Handbook of Steel Drainage and Highway Construction Products book'. Division Response: In the submittal dated July 8, 2011, the Sedcad design pages showing peak flows were provided as requested. As far as the design pages showing the sizing of the culverts, CAM elected to depend on a reference on page Exh 9 -2 to Figure 4 -18 of the Handbook of Steel Drainage and Highway Construction Products. Since that reference book may not be readily available to others, the Division requests that one generic copy of Figure 4 -18 be included with the culvert designs. 57 — 60a. Items resolved.