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Forrest Luke, TMI <br />Page 2 <br />11/20/2014 <br />Based on the November 12, 2014 meeting, it was agreed that the proposed revised permit text <br />in section 4.8.1.3 of the permit could be expanded to clarify how Trapper will utilize the <br />information obtained from the model to determine the number of checkdams and dozer basins <br />that will need to be installed in the reclaimed drainages. Also, it appears additional figures <br />will need to be added or the current figures will need to be modified. Below is a list of items <br />the Division believes will need to be addressed: <br />a. All of the documents e- mailed to the Division on August 29, 2014 should be included <br />in Trapper's permit as an appendix. These documents include "Guideline for the <br />Design and Number of Dams and Dozer Basins for Erosional Control of Reclaimed <br />Lands for Bond Release Under a Variety of Channel Conditions Using SEDCAD <br />Modeling ", "Appendix A through H ", "Figures 1 through 10 ". <br />b. Revised section 4.8.1.3 needs to include wording to commit to construct the post <br />mine drainages in accordance with the typical design depicted on Figures 4.8 -1a and <br />4.8 -1b. <br />c. Proposed Figures 4.8 -1c and 4.8 -1d depict graphs that can be utilized to determine <br />the number of check dams to be installed within a section of reconstructed drainage <br />based on drainage area and a curve number at a 10 or 15% slope. The curve number <br />used to generate these graphs was 78 and 72 and represents a portion of a reclaimed <br />watershed at different stages of reclamation. The Division believes that a 78 and 72 <br />curve number used to determine the number of rock check dams does not reflect the <br />worst case scenario of the land condition contributing to the drainage channel at the <br />time of construction. During the meeting, Trapper explained that they would actually <br />like to vary the curve number used to determine the number of check dams to be <br />installed in a given portion of channel based on the reclamation stage of the <br />watershed contributing to the channel and that they did not intend to use a design <br />base on only the two curve number presented (78 and 72). Given this, the Division <br />believes Trapper needs to either revise Figures 4.8 -1c and 4.8 -1d or add additional <br />figures for all of the curve numbers they intend to use to determine the number of <br />checkdams to be installed. Also, please include additional permit text to discuss what <br />criteria will be used to select a given curve number. <br />d. It was discussed that the slopes depicted on the figures discussed above do not <br />represent the range of slopes encountered within a reclaimed watershed. For the new <br />and /or updated figures, please include additional slopes for the various curve <br />numbers to be used to ascertain the number of check dams to be installed. <br />e. During the November 12 meeting, Trapper indicated that the number of checkdams <br />to be installed within a reclaimed drainage may be different than what the model <br />discussed above indicates are needed based on whether or not dozer basins are <br />installed within the channel. The proposed drainage stabilization plan does not <br />describe how Trapper will determine the number of check dams will be installed if <br />