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Twentymile Coal, LLC. <br />Page 7 <br />November 16th 2018 <br />3. It is unclear if a cultural resources survey has been conducted for all areas of the proposed <br />disturbance at the new location. The corridor for the input pipelines are not shown. The text on <br />page 2.05-45.28 and referenced revision (MR -295) appear to be for the previous location. Please <br />ensure cultural surveys have been completed for all areas of currently proposed disturbance <br />including the proposed road and pipelines, and provide appropriate references. <br />4. The Division spoke with the Division of Water Resources in regard to the proposed revision on <br />the mines augmentation plan. The Division of Water Resources indicated that the mine's current <br />augmentation plan is not adequate. Please work with the Division of Water Resources to resolve <br />this issue and provide an acceptable updated augmentation plan that includes the proposed <br />passive treatment system proposed in this revision. <br />5. Exhibit 49EE Appendices D and E do not appear to have been updated for the new location. The <br />previous location was determined to a wetland so the data does not likely have a strong <br />correlation to the new location. Please provide data for the new location or explain why this <br />would not be unnecessary. <br />6. The designs and exhibits provided by the mine's consultant appear to be a recommended scope of <br />work not necessarily the operators proposed construction. The 2016 submission included Exhibit <br />49EE-F 1 and F2 map of the 6MN Passive Water Treatment System signed by a TC engineer. <br />Please provide this level of labelled detail and clarify and specify exactly what TC is proposing to <br />construct. <br />7. It is not clear how the topsoil for this disturbance will be handled. Please clarify, and if there will <br />be new topsoil piles, please add these to the maps. <br />8. Please specify the plan for vegetating the proposed passive treatment system including what plant <br />species will be placed and at what frequency. <br />9. Section 2.2 of the design report references Appendix A Treatment Performance Modeling, which <br />present in the 2016 submission but was mostly cut out of the 2018 submission. This included <br />approximately 10 pages of what appears to be relevant data on temperature, evaporation, and <br />analyte removal rates which affected the sizing and anticipate performance of the treatment <br />system. Please include this information or explain why this data was removed. <br />10. Please provide additional design details and sizing for the AgriDrain System. It is not clear what <br />dimensions TC intends to use and pipe sizing between text and diagrams are not consistent. It is <br />not clear what if any maintenance is anticipated to assure function as designed. <br />11. Please provide additional design detail for the Cascade at the inlet of the system, including the <br />peak flow volume, rational for stone sizing, identification of vortex stones which are in the text of <br />the diagram but not labelled. <br />