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TR-62- Midterm Review Responses (2nd round) <br />Page 5 <br />Response: The map accompanying the Rick's request letter shows the entire road (existing and new) for <br />the landowner's benefit. The only portions of these roads that the Division should be concerned with <br />are the portions within the disturbed/mined area. These portions are correctly indicated on Exhibit 20- <br />2, Postmining Topography and Drainage. <br />8. Page iii of Tab 13 omits the listing for Exhibit 13-9E, `Pond 016/ 016A Two-Pond System As-Built Watershed <br />Boundary': Please correct. <br />Response: Tab 13, TOC, page iii has been updated to include Exhibit 13-9E, Pond 016/016A Two- <br />Pond System As-Built Watershed Boundary. <br />9. Tab 13, page 23 - New culverts HRC J6, HRC J7, K-3, PM-15, and PM-17 are listed as supplemental culverts to <br />assist design. Please provide design calculations for these culverts, update Exhibits 13-2 to include all culverts, and <br />update Exhibit 20-2 to include all culverts proposed for permanent retention. <br />Response: When the road designs were approved, there were culverts designed and located by <br />watershed along the roads (see Exhibit 13-2, Surface Hydrology). <br />The culverts, you mention, are "supplemental culverts" (see Exhibit 20-2, Postmining Topography and <br />Drainage). They are additional culverts that were installed (field-fit) during/following construction <br />and/or reclamation to ensure that positive drainage was maintained within the watershed. These culverts <br />are oversized, in that they are the same diameter as the single culvert that was originally approved to <br />handle all the flow. When these culverts were added it was the Division's decision that a culvert design <br />calculation was not required. <br />10. The new material submitted by SCC includes design information/ calculations for new culvert PM-16. The new culvert <br />is also shown on Exhibit 20-2. It is not shown on Exhibit 13-2, the surface hydrology map. Please update Exhibit <br />13-2 to include PM-16 and update the drainage basin boundaries Without the updated map we cannot review the <br />adequacy of the PM-16 design. Also, please update the culvert tables of pages 13-23 and -24, and 13-7-1 or -2 to <br />include information for PM-16; the rows designated PM-16 are blank. <br />Response: SCC didn't realize that a 1.8 acre watershed was going to become such an issue; so SCC has <br />included this watershed on Exhibit 13-2, Surface Hydrology, as requested. Once again this is a <br />"supplemental culvert", since the approved road design doesn't even require/show a culvert for the <br />larger watershed on the current Exhibit 13-2. As shown in the SEDCAD run for this culvert, only a 6 <br />inch culvert is required to safely handle the calculated flow, however a 24 inch culvert has been installed. <br />Tables 13-5 and 13-7-1, and Exhibit 13-2, Surface Hydrology have been revised and are attached. <br />11. Exhibit 13-25.2 states that it was revised with MR-61; it should be corrected to refer to TR-62. <br />Response: The revision date is correct....The Exhibit was submitted as MR-61 in 2006. The Division <br />asked that MR-61 be withdrawn, but that does not change the information or when it was certified. The <br />reference to MR-61 can be simply crossed out and TR-62 written in (as SCC is going to do with our <br />copies) or the enclosed label (TR-62) can be pasted over the MR-61. <br />Seneca Coal Company • P.O. Box 670 • Hayden, Colorado 81639 <br />Telephone (970) 276-5219 • FAX (970) 276-5222