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Chris Gilbreath <br />Page 5 <br />20 May 2015 <br />h. The page numbers for figures for Exhibit 7 -PP appear to be incorrect. They say "14PP" <br />rather than "PP." Please review the numbering and correct as necessary. <br />i. The collection ditches in Exhibit 7 -PP are labeled as contour ditches. This is creating <br />confusion. Please review the ditch labeling and correct as necessary. <br />j. The slopes in SEDCAD model seem to be greater than those shown on the topographic <br />map in Figure Exh. 7-14PP-8. Please chack the slopes in the SEDCAD model and <br />correct as necessary. If this was done to be conservative in the SEDCAD modeling <br />please provide an explanitory note. <br />k. The SEDCAD model in Exhibit 7 -PP shows the contour ditches being riprapped. This is <br />not a common practice for contour ditches. Please explain why the SEDCAD model <br />has riprapped contour ditches. <br />1. Page Exh. 7-20C-1 ( in Exhibit 7, Item 20, Part C) contains errors that need to be edited. <br />It mentions the East Taylor Tributary Ditches, which are removed with this submittal. <br />Additionally, there is extraneous text on fourth line ("Exhibit 7, Item 20"). Please <br />review this page and make corrections as necessary. <br />in. There appear to be several errors with Table 4 in Exhibit 7, Item 20, Part C. For the West <br />Taylor Pond, the emergency spillway elevation and the riser height are different than the <br />drawing. Under West Taylor, post -mining, the emergency spillway discharge says <br />"Final." This appears to be an error. Please review the inputs in Table 4 and correct <br />as necessary. <br />n. In Exhibit 7, Item 20, Part C there appears to be a descrepancy between the curve number <br />shown on the map and in the SEDCAD model. The map shows a CN of 74 and the <br />SEDCAD model shows a CN of 77. Please review these curve numbers and correct <br />the one that is in error. <br />o. Please explain why all subwatershed lengths in Exhibit 7, Item 20, Part C are <br />limited to 200 feet (as shown in sedimentology detail). <br />p. In Exhibit 7, Item 20, Part C it appears that some of the SEDCAD models are missing the <br />Subwatershed Sedimentology Detail. Please review the SEDCAD models and provide <br />the sedimentology detail. <br />q. Please discuss the use of stock ponds in the introductory text of Exhibit 7, Item 20, <br />Part E. <br />r. Please re -run the model with actual elevations for the stock ponds (rather than 90, <br />100, etc.) in Exhibit 7, Item 20, Part E. <br />s. In Exhibit 7, Item 20, Part E, the subwatersheds for the West Taylor West Tributary <br />Ditch should not straddle the ditch to make each one have a homogeneous curve number. <br />Rather, a given subwatershed should be on only one side of the ditch, and the curve <br />number should be determined from an area -weighted average. Please review the way <br />the subwatersheds were drawn and remodel the West Taylor West Tributary Ditch. <br />t. Please explain why the channel near the 8000 -foot elevation in Exhibit 7, Item 20, <br />Part G is not the representative channel; it has a much larger total drainage area <br />than the channel at the 7900 -foot elevation (although the fill area is smaller). <br />