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Keeping and using Pond 5 as an active sediment retention facility was not in the original <br />reclamation plans and should not be assumed to be an active, indefinite sediment detention <br />facility. This pond was originally slated to be removed and reclaimed. Pond 5 and the two <br />culverts under the road will require continued long-term maintenance, especially since one of the <br />culverts has already shown signs of deterioration. Perhaps removal of these culverts would be a <br />best management option at this time. No support has been provided to demonstrate that the holes <br />in the culverts do not impact the flow capacity or function of the culvert nor that these holes do <br />not impact the structural integrity of the culverts. <br />Dr. Corley has surveyed the topography of Pond 5 on at least two different dates (2011 and <br />2016). Results of the difference in volume of his topo survey of Pond 5 demonstrated that since <br />2011 (the last time the pond was cleaned out) an average annual rate of 68 tons of sediment per <br />year since 2011 have been eroded, transported, and deposited into Pond 5 (dated January 6, <br />2016). The overall annual sediment yield per acre is greater than 68 tons per year as this <br />measured value is a very conservative estimate since some portions of the reclaimed land drains <br />to the Magpie Creek watershed, some drain into the Vento pond, and this measured value does <br />not include any sediment deposition near the green gate on the west side of County Road 92. <br />The conclusion of the sediment report was that the RUSLE model output demonstrated that the <br />existing reclaimed condition is better (produces less sediment) compared to a non -mined <br />condition. This is an incorrect conclusion because the RUSLE model output only demonstrated <br />a very small change in vegetation cover for the exact land condition. The demonstration that <br />greater vegetation cover results in less erosion is probably the most abundantly reported result of <br />erosion research and is clearly supported in the scientific literature, but it is not the only variable <br />that affects erosion. <br />No other variables in the RUSLE model were used during this analysis, only vegetation cover. <br />The assumptions that soil type, slope length, and slope gradient would be exactly the same in <br />both reclaimed and non -mined areas only demonstrated simulated output of annual sediment <br />yield at the same location or same condition, with only a slight change in vegetation cover (4%). <br />This demonstration does not show any comparison between existing reclaimed condition and <br />non -mined condition or pre and post mine condition as implied. The sediment report and model <br />demonstration also lacks the best available information, best available techniques and <br />technology, fails to provide any model validation, nor give proper citations or explanations for <br />the selection of this method or selection of model factor values. For example, the P -factor has a <br />value of "1" for both reclaimed and non -mined conditions and in a multiplicative equation "1" <br />has no impact; no reason or support material is provided for this choice. The current sediment <br />analysis shows little and fails to show what it claims to demonstrate. I believe a proper sediment <br />analysis over the entire permit area would be very useful to identify areas that are probably <br />contributing greatly to the observed sediment deposited in Pond 5 and the erosion and sediment <br />near the green gate. I suspect bond release regulations do not require a true scientific approach <br />to erosion modeling if what has been presented to date is being considered appropriate. <br />Another problem with my ability to following the logic and procedures of the sediment report is <br />where some values, statements, and assumptions that were used in the sediment report originate. <br />