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<br /> <br />we disagree with the assumptions and the results. Based <br />on the pre-mining cover data submitted with the revision, <br />the pre-mined area "C" factor should utilize the "G" type, <br />or at the very least, a weighted combination of the "G" <br />and "W" types. The cover presented on page B-17o does not <br />correlate strictly to the "W" type (cover at the surface <br />is mostly broadleaf herbaceous plants (as weeds with <br />little lateral root network near the surface and /or <br />undecayed residue)). The cover data understory is <br />approximately a 50-50 mix of perennial and annual grasses <br />and forbs. Please re-interpolate the "C" factor with the <br />proper assumptions and use the resultant number in the <br />equation. <br />Also, we believe that more material can be used (see <br />below) to complete the backfilling which will result in <br />slightly different final contours and slopes. Once this <br />new configuration is approved, the equation will need to <br />be re-calculated using these new slope and "C" factor <br />numbers to show that soil loss from the reclaimed area is <br />still less than that from an adjacent unmined area. <br />(e) No comment. <br />(f) The safety factor may have to be re-calculated based on <br />the additional material and final contour configuration. <br />General Comments <br />From reviewing map C8-1226R (post-mining topography map) it is <br />apparent that a small terrace or bench type structure is being left <br />between the 6350 and the 6375 contour levels. The Division feels <br />that this bench should be backfilled and graded out to blend in <br />with the fall line for the rest of the slope. Please revise the <br />plan and map C8-1226R to illustrate the post-mining topography <br />without this bench. As previously mentioned, this may change both <br />the USLE and safety factor calculations. <br />A final issue that requires clarification is whether or not this <br />fan area was developed pre-law. It is my understanding that the <br />fan was installed in the early 1970's. If that is true, it may <br />affect the requirements for how reclamation is performed in this <br />location. Please provide any information available about when the <br />fan portal was installed. <br />This concludes the review. If you have any questions, please <br />contact me. <br />Sin erel , <br />~ "V~~ <br />Anthony J. Waldron <br />Environmental Protection Specialist <br />