2015-05-20_REVISION - C1981019 - Laserfiche WebLink

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Chris Gilbreath Page 4 20 May 2015 landowner approval for the proposed post -mining topography. These letters should include, at a minimum, BLM and CPW. Rule 4.27 — Operations on Steep Slopes 17. During the permitting of the South Taylor Pit (Permit Revision 2), the Division approved a variance from approximate original contour (AOC) for steep slope mining for portions of the South Taylor Pit. With the submittal and subsequent approval of Technical Revision 81, this variance was no longer necessary. It is the Division's opinion that, given the proposed post - mining topography in Technical Revision 105, the original variance from AOC, approved with PR -02, is still not necessary. The Division believes that the text in Rule 4.27, while historically accurate, is somewhat confusing given the current state of operations in the South Taylor Pit. Please either revise the text in Rule 4.27 (starting on page South Taylor/Lower Wilson — Rule 4, Page 22) with current information or eliminate it. Rule 4.05 — Hvdrolo6c Balance 18. The following items are related to the SEDCAD modeling provided in Exhibit 7. a. In Exhibit 7, Item 14, Table 1, Taylor Tributary Ditch, one of the rows has stations of 35 to 79+89. Should this row be 40 to 80? b. In the SEDCAD printout in Appendix Exh. 7-14C, Subwatershed Hydrology Detail, there appears to be an error for structure 43. The UHS value is "8.07" but should likely be "M." Please confirm that this is just a printing error and not a problem with the model. c. In Appendix Exh. 7-14E, the subwatersheds appear to be poorly delineated. This was also a technical adequacy issue for Technical Revision 97. Please delineate the subwatersheds in a conventional way or explain the rationale for the way they were done in this way. d. In Appendix Exh. 7-14E Streeter is in Sections 2 and 16 also (not just 3, 9, and 10). Please correct this discrepancy. e. The intro discussion on different modeling efforts in Exhibit 7 -SP warrants a discussion between Colowyo and DRMS. Some aspects are unclear: for example, why the sub - watersheds for the ditch modeling are different for the pond modeling. The sub - watersheds for the pond model are not as strange as those for the channels, but are still unusual. f. Please rewrite introduction to this Appendix Exh. 7-14I to make it clear that the model for all of Taylor Tributary Ditch (including East Taylor Ditch) varies from model for East Taylor Ditch (from Technical Revision 104). g. The design flows in Table 1 of Appendix Exh. 7-14I appear incorrect for upper reaches. Please review the design flows and correct as necessary.