Laserfiche WebLink
STATE OF COLORADO <br />DIVISION OF MINERALS AND GEOLOGY <br />Department of Natural Resources <br />1373 Sherman 5[., Room 275 <br />Denver, Colorado 80203 <br />Phone: 1303) 8663567 <br />FAX: (303) 832$706 <br />INTEROFFICE MEMORANDUM <br />DIVISION OF MINERALS AND GEOLOGY <br />TO: Dan Mathews <br />FROM: Mike Boulay <br />DATE: Mazch 10, 2006 <br />SUBJECT: Seneca Coal Company (Permit No. C-82-057), <br />Permit Revision No. 5 -Review of Adequacy Comment Responses <br />OLORADO <br />( V I S I O N O F <br />IINERALS <br />EOLOGY <br />CLAN ATION•NININO <br />SAFETY•ECIENCE <br />Bill Owens <br />Governor <br />Russell George <br />E><ecu[ive Director <br />Ronald W. Canny <br />Division Director <br />Natural Resource Trustee <br />I have reviewed SCC's response submittal to our PR-OS adequacy review letters. My original <br />comments from my August 8, 2005 memo aze now numbered as items 10 through 17 in SCC's <br />response letter. As requested, I have reviewed all revisions to postmine channel designs, SEDCAD <br />model demonstrations, drainage and sediment control plans, culvert designs, and stock pond <br />designs. With exception of sedimentation ponds, the entire II-W South posimining drainage and <br />sediment control plan was revised. In addition, SCC also provided revised designs in the original <br />permit azea for select channels and culverts. I have the following remaining comments. <br />10-11. Items resolved. <br />12. Response accepted. Since SCC has revised all postmine channel designs, the Division has <br />the following comments regarding the new channel designs and culvert designs. <br />12a. The Pader method design for Channel PM-2 at both 11 % and 18% slopes indicates a D50: 6 <br />inch riprap. Based on footnote 2) of Figure 20-1.2 4 (Riprap D50 sized by taking the Pader <br />Method Design size and doubling), the Lining Type given for PM-2 should be 12 inch as <br />opposed to 9 inch. Please revise Figure No. 20-1.2 accordingly. <br />12b. The SEDCAD design provided for Culvert PM-12 is the same design information presented <br />for PM-11. Please revise pages 13-7-243 through 13-7-250 to include an appropriate <br />SEDCAD demonstration and pipe size information for PM-12. <br />13-14. Items resolved. <br />15. Response accepted. However, it was noted that a stock tank designation was not included <br />in the Legend of new Exhibit 20-2. Please add Stock Tanks to the Legend of Exhibit 20-2. <br />Office of Once of Colorado <br />Mined Land Reclamation Active and Inactive Mines Geological Survey <br />