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dam spacing does not conform with design in various sections. Please review and amend <br />applicable text, designs, and maps as warranted to provide necessary clarification and <br />eliminate inconsistencies. Also, please address field modifications that will be <br />necessary to achieve conformance with approved designs, and provide a schedule <br />committing to completion of the work (completion no later than October 1, 2002). <br />RP-SB Diversion <br />Designs aze also provided for RP-SB undisturbed diversion, a V ditch with d=2.52' and <br />tw=10.09'. This ditch is erroneously referred to as RP-6 diversion on p. IV-20. <br />e) Based on observations documented in the April 10, 2002 inspection report, the ditch as <br />installed is trapezoidal rather than triangulaz, with a typical cross-sectional area roughly <br />equivalent to approved design. Please amend the permit as necessary to document <br />the adequacy of the existing installation, or implement without delay aay necessary <br />field modification. <br />RP-2/3/4 Ditch Designs <br />Page IV-19 (Section IV.D.3) indicates that drainage and sediment control structures will be <br />maintained to be stable and functional at all times, and further states that construction of <br />permanent ditch segments affected by final reclamation in refuse area 2/3 perimeter <br />collection ditches and refuse area 4 perimeter collection ditches will be delayed until final <br />reclamation. Similarly, the revegetation of collection ditches currently subject to deposition <br />of coaly sediment and frequent maintenance will be completed after the fnal revegetation <br />of refuse piles are completed. Interim measures will be taken to control sediment and ditch <br />erosion. Such measures may include some or all of the following... temporary rock check <br />dams, straw bale check dams, dug out sediment traps, rip rap or other ditch lining, contour <br />ditching along slopes of refuse areas, and land impringing using sheep's foot compactor for <br />refuse slopes, and... use of clarifying agent... in sediment ponds. <br />Interim or in pit...ditches will also be sized ... to pass the runoff from a 100 year, 24-hour <br />storm. The ditches will be designed to carry the design flow depth and 0.3 feet of freeboard <br />in all areas including the riprap and checkdam sections. <br />~ Map 150 depicts approved RP-2/3/4 perimeter collection ditch locations. Ditches that <br />lead to Pond RP-213 are broken into segments numbered 1 through 8, as aze ditches that <br />lead to Pond RP-4. Channel gradients for each ditch segment aze listed on the map. <br />The map includes one note that states "All Ditches Interim Until Final Reclamation", <br />and a second note that states "For Ditch Cross Sections See Permit Maps 78, 79, and <br />80." The second note appears to be erroneous, since the referenced maps do not <br />contain ditch cross-sections relevant to RP-2/3/4. Please delete the erroneous note <br />from the map. <br />Deserado Mine Apri130, 2002 <br />14 <br />