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RP-1 Permanent Ditch Desi¢ns <br />j) Map 78 is Sediment Pond RP-1 plan, sections and details. The map contains 1 ditch <br />cross section with separate dimensions specified for "west ditch" and "east ditch". The <br />west ditch cross section shows a V ditch 1.8'deep by approximately 7'wide, and east <br />ditch cross section shows a V ditch 1.6' deep and approximately 6.4' wide, and slopes <br />exceeding 1.2% riprapped. Our Map 78 copy lacks an original P.E. stamp and <br />signature, and a properly stamped and signed copy of the map is requested. <br />k) Illustration 4 contains sub-azea RP-1 pond and ditch design calculations. East ditch <br />designs specify a V ditch 1.5 feet deep for both upper, non riprap sections, and lower, <br />riprap sections. West ditch design is a V ditch 1.7' deep for upper, non riprap sections, <br />and 1.5' deep for lower, riprap sections. The design specified on Map 78 is very close, <br />but slightly more conservative than Illustration 4. Please amend as appropriate to <br />rectify this inconsistency. <br />1) Map 77 depicts perimeter containment ditch locations. The April 10, 2002 inspection <br />report indicated an appazent discrepancy regarding the location of the lower segment of <br />the west perimeter ditch, as compazed to the on-the-ground installation. Please address <br />the ditch location discrepancy, including a description of any necessary field <br />modification, and amend Map 77 as warranted. <br />2.05.6(3) Protection of Hvdroloeical Balance <br />15. Based on review of recent Annual Hydrology Reports, Subsidence Monitoring Reports, and <br />in order to reflect the cunent extent of mining, we request that the probable hydrologic <br />consequences (PHC) section of the permit application be updated to incorporate the <br />following observations: <br />a) Section 2.2.1.2 of the 2001 AHR (17s' Annual) includes a discussion regazding the <br />effects of Kenney Reservoir on White River alluvial water quality in the vicinity of the <br />mouth of Scullion Gulch. The narrative in this section references "potential effects" that <br />"were projected that the dissolved solids of the...alluvium...would increase <br />initial]y...TDS would then gradually decrease...to neaz or slightly above baseline <br />conditions..." The AHR seems to imply that the trend of initially increasing TDS <br />followed by gradual decline (which is reflected by data in Table E-4 of the AHR) was <br />projected in the PHC section of the permit application. In reviewing the PHC, we have <br />not found the referenced projections regarding effects of Kenney Reservoir on White <br />River alluvial water quality in the permit area. Please amend and update the PHC as <br />appropriate to reflect the documented trend, with inclusion of discussion of <br />anticipated and apparent impacts of Kenney Reservoir. <br />Deserado Mine <br />Apri130, 2002 <br />16 <br />