2013-07-29_REVISION - C1981010 (3)

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Trapper Mining, Inc. C- 1981 -010; PR7 Adequacy Review No. 1 Page 4 of 7 the warranty deed. It is unknown if the lots described in the warranty deed for Sections 4 and 8 of Township 5 North and Range 90 West cover the expansion permit area. The expansion area in section 9 of Township 5 North and 90 West does not appear to be covered in any of the descriptions in section 1.3.1.1 in the permit. Please update this permit section accordingly. 3.3.3 East Panel Landslide Geotechnical Evaluation 20. On page 3 -27b, Stations 5 to 8 have replaced Stations 1 to 4 that were listed previously. For the purposes of continuity, a new paragraph should be inserted at the top of page 3 -27b which gives a brief description of what happened to the original four stations, and when the current stations were placed in service. 4.08.1 Surface Water 21. The current page 4 -173; section 4.08.1.2, discusses haul road culvert sizing. This section references Tables 4.8 -1 and 4.8 -1a which are proposed to be replaced with Table 4.8 -2 and 4.8 -2a submitted with the revision. Please update the permit text on this page with the revised table numbers cited. 22. Proposed Table 4.8 -2; Haul Road Culvert Sizing, lists the culverts that exist at the site. The following culverts were added to the table and depicted on the revised M51 maps; ASH -1, ASH -2, BH -1, EMF -1, MZ -1, MZ -2, MZ -3 and MZ -4. It appears these culverts have been installed but were not part of the current approved permit. Also, many culverts are depicted on the M5I(Sheet 3) map for proposed culverts that appear to be for the future haul roads to be constructed in the next permit term. Rule 4.03.1(4)(e)(v) indicates that "culverts shall be installed to accommodate flow from the intersecting drainages, and from road surface drainage as necessary to control erosion. Designs for culverts shall be in accordance with 4.03.1(4)(e) except where alternative specifications are approved." Permit section 4.08.1.2 indicates culvert sizes are determined by running hydrologic models. For the culverts listed above and the future culverts to be installed, please submit the information/parameters used to determine the proper culvert sizing. Other Operators submit copies of the SEDCAD runs they use to design culverts. 23. Trapper did not submit detailed designs for post- mining drainage channels, as required by Rules 2.053(4), 4.05.3(1), 4.05.3(1)(e), 4.05.3(7). c. Rule 2.053(4)(a) — A general plan and detailed design plan shall be submitted for each sediment pond, impoundment, other treatment facility and diversion proposed to be constructed within the permit area. Please provide detailed design plans for each postmining drainage channel. d. Rule 4.05.3(1)(e) — channels must be designed, located, constructed, maintained, and used to minimize adverse impacts to the hydrologic balance, and to be stable. Trapper has offered details on how the channels might be constructed and maintained, but has not provided specific design information. Please provide design information for each postmining drainage channel to include the minimum channel dimensions and details of any required velocity reduction measures. The dimensions and channel properties must be based on the anticipated runoff for each specific watershed, based on watershed size, topography and cover; the design precipitation event; runoff potential, etc. e. Rule 4.053(7): i. channel linings, including channel riprap, shall be designed using standard engineering practices to pass safely the design velocities. Please provide design information for each postmining drainage channel to include the minimum channel dimensions and details of required velocity reduction. The dimensions and channel properties must be based on the anticipated runoff for each specific watershed, based on watershed size, topography and cover; the design precipitation event; runoff potential, etc.