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VOLUME 13 <br />14. Within the Section 28 Pond watershed, it is highly recommended that Tri-State consider the construction of stock <br />tanks below Trib D and the other disturbed areas near the ridge. (It appears that one stock tank already exists <br />below Trib D.) This would reduce the velocity of the peak discharge in the Natural Channel, which is above 15 <br />feet per second during the 25-year storm, per the SEDCAD printout (pages 6-7). Also on this printout, the <br />limiting velocity of 6 feet per second is listed for shales and hardpans. <br />15. The curve number for the "purple" areas on Figure Exh. 7-20A-2 is shown as 57 in the legend of the figure, but <br />this should be changed to 47 per the SEDCAD pages. Please make this change to the figure (or update SEDCAD <br />if appropriate). <br />16. When reviewing the West Taylor Pond text: <br />a. Please add to the text an explanation of how the CN values in the SEDCAD model were chosen for the <br />worst -case hydrologic condition. <br />b. There appear to be errors in the text on page Exh. 7-2013-1. The references to figures in the first paragraph <br />should likely say "7-20B" rather than "7-20C." <br />c. The introductory text for the West Taylor Pond hydrology approach should include a discussion of the <br />geomorphic reclamation techniques proposed by Tri-State with TR-145. With this discussion, anyone <br />who looks at the hydrology approach and design will understand that this method is being used and why <br />this method entails significant benefits compared to conventional designs. <br />d. Map 12 indicates that a portion of Trib 1 flows over the permanent fill, however this channel is designed <br />for the 10-year storm (rather than the 100-year storm). Please explain this in the introductory text or <br />revise the design to meet Rule 4.09.2(7). <br />e. In the SEDCAD model for East Fork Taylor Ditch, a roughness coefficient of 0.12 is shown (see page 10 <br />of the 100-year model). Given that this is unusually high, a discussion of this factor is warranted in the <br />introductory text. Perhaps it belongs in the text related to the geomorphic reclamation techniques. <br />Perhaps it could be stated that this is a conservative factor in the analysis. <br />17. When reviewing the West Taylor Pond figures: <br />a. The watershed boundaries map (Figure Exh. 7-2013-2) contains three shades of green indicating different <br />CN values, but the map legend only shows two shades of green. Please revise the map or explain this <br />apparent discrepancy. <br />Volume 14 <br />18. With the changes to post -mining topography as part of the proposed Colowyo TR-145, please provide an updated Map <br />35A - Bond Calculation Map Worst Case Topography. With the updated Map 35A, please provide the Division updated <br />volumes associated with each reclamation polygon to allow the Division to accurately calculate the reclamation cost <br />estimate with the TR 145 proposed changes per Rule 3.02.2. <br />This concludes the Division's adequacy review for the Colowyo TR-145. If you have any questions, feel free to contact me. <br />Sincerely, <br />