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<br />negli gi bl a, because those structures have heen deaS goad to minimize impacts to the <br />hydrologic balance (sea Tab 13, Facilities). The di versa one and cut verts lnvol va suth <br />minor aresa of di aturbance that chemical and sediment changes in the flaws wS 11 be <br />unmeaaurebla. <br />Effects of Runoff from Reclai mad Areas on the Quanta try of Strearoflow. Tha effects of <br />runoff }ras the proposed Nucla Eeat mining area on streamfl ow quantity (runoff and <br />sediment loads) have been estimated using the luropad-parameter computer erode] SEDITiOT 11. <br />The impact is o/ runoff Tres reclaimed aresa established at the Nuela Mt ne are inferred from <br />this modeling exercise. As previously mentioned, the absence of detailed premi ping <br />mappi rtq, and ciao the lack of eomprehensi ve soils a:W vegatati on data for the Nuela Hine <br />prior to the onae[ of mining precludes the use of SEDIMOT !I to obtain meaningful <br />premi ni ng estimates of runoff and sedi me:K loads for comparison with poslmini ng estimates. <br />SEDIMDT II has been developed to predfet runoff and sediment loads from watersheds that <br />have been mi nod or are in the pros eaa of active mining, Input pa rametera take in[o <br />account precipitation. soils, topography and vegetation. Atl~uetment of eh esa parameters <br />a11ow9 9or the ava7vatS on of watershed response changes resul tS ng Pras mining. <br />• <br />input paranuftera selected for the model refieet both premTning and postmi ning Craelai mad) <br />condi Lions, and reaul led in two separate model outputs: 1) pram ning runoff and soda ment <br />loads= and Z) postmi ning runoff and sediment loads. Both outputs include runoff volumes <br />and rates (peak dt SOharge), sediment concentrations and sediment yields. The following <br />sections di scusa the scope of the modeling efforts, the aaleeti on of input parameters, and <br />a aumiery of the modal results M th correspondt ng si gnifi canoe detarmi nations. The reader <br />should refer to the SEDIMOT 1{ Manuel on Modeling Technlquea (Wilson, et al ., 1961) and <br />the SED IFIOT II User's Manual (Warner, at at „ 1901) for reference. <br />Tha watershed Brea dT racily above the proposed 007 pond (Nucla Eaat mining area) was <br />selected }or evaluatTrg runoff an0 sediment loatls using SEO INOT It. The small area <br />located in the southeastern DortS on of the Nucla East ni ni ng area that Ts drained by the <br />proposed diversion ditch wsa not included, as both the diversion and the sediment pontl <br />will De removed after bow release (poatmining Bondi tions). Exht bits 77-1 and 17-2 <br />present the epproxt mate drainage areas end respneti ve topography ea Tor bosh premi ning and <br />postmi ni ng coed tt{ons. <br />17-82 Revised 04/11/88 <br />1f <br />u <br />REVISED MARCH 2006 <br />Attachment 2.05.6(3)-2-94 <br />