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Response to Comment #18 <br />Areas of potential erosion where EFCI is responsible are insignificant and are similar to adjacent, un - <br />mined areas. <br />Corley Comment #19 <br />In his letter, Dr. Mergen wrote the following: <br />The sediment demonstration report incorrectly and selectively applied vegetation cover in the sediment <br />demonstrations. The analysis used specific portions of the permit area with the greatest vegetation <br />cover. Also, no statistical variability is considered in the analysis. <br />Response to Comment #19 <br />The Division believes that vegetative cover was used correctly and finds the sediment demonstration <br />acceptable. <br />Corley Comment #20 <br />In his letter, Dr. Mergen wrote the following: <br />Included in the report were additional comments without any accompanying support material, such as <br />mention of sediment ponds, the idea that vegetation will continue to improve, and observations of no <br />sign of erosion beyond what is occurring in adjacent areas. EFCI makes the generalization that there <br />is less erosion in many places and does not provide evidence of self -healing. <br />Response to Comment #20 <br />The Division considers these comments by EFCI extraneous. They are not necessary for the <br />sediment demonstration. However, they are, in many cases, consistent with what has been observed <br />by the Division on the mine site. <br />Corley Comment #21 <br />In his letter, Dr. Mergen wrote the following: <br />There are more sophisticated hydrology models than RUSLE. <br />Response to Comment #21 <br />The RUSLE is accepted methodology for sediment demonstrations for bond release applications. <br />Corley Comment #22 <br />In his letter, Dr. Mergen wrote the following: <br />Some of the source material for the road and ditch was wash -plant reject material, which may be <br />much more erosive than the reclaimed areas. The most observable impacts are seen within Pond 5 <br />and outside the permit boundary. <br />Erosion of soil from County Road 92 and its ditches has become a greater or more obvious problem <br />recently because of lack of maintenance. While EFCI was actively mining, any road maintenance <br />near the mine was accomplished either by the Fremont County maintenance crews or by EFCI, so <br />large gullies and ditches across the road did not form or were quickly repaired. Road ditch armoring <br />at erosive points was alsq used. <br />Response to Comment #22 <br />The issue of erosion from this road may warrant further discussion, but it is not related to SL -03. <br />Southfield Mine SL -03 Page 8 of 21 February 23, 2016 <br />