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documented in this plan. <br />Configuration #2 represents early 1997 and essentially the current drainage <br />system. There are a limited number of changes in the drainage subbasins compared <br />to the previous Configuration #1. All changes relate to the changing nature of <br />the surface and topography as the overburden approaches the sump and, therefore, <br />the changes modify the amount, and direction, of runoff from the subbasins. The <br />drainage area changed is, in large part, the overburden storage area surface. <br />The Bl -3 subbasin of Configuration #1, which this change affects, is expanded to <br />incorporate much of subbasin the Configuration #1 B1 -5 subbasin and it becomes <br />subbasin B2 -1 for this Configuration #2. The remaining part of the B1 -5 subbasin <br />is re- designated as the B2 -2 subbasin. Configuration #2 shows the completion of <br />the first lift of the storage area. CC &V currently plans to initiate <br />revegetation of the first "face of the Stockpile in this Configuration. <br />Configuration #3 depicts the storage area later in 1997, at the stage when the <br />western face of the first lift is filled, graded, and revegetation activity on <br />the face of the first lift is completed, and as the second lift is constructed, <br />At this time, the northeast edge of the storage area remains outside the southern <br />limits of the Mine area. In this Configuration, the drainage channel G -H, which <br />conveys water. from the small watershed located upgradient of the overburden <br />storage area, is developed early in the sequence to lead to Pond SP -1. Subbasin <br />B2 -1 of Configuration #2 changes again, this time to a larger subbasin B3 -2, by <br />incorporating much of subbasin 31 -6 (which remained through Configurations #1 and <br />#2). Subbasin B2 -2 of Configuration #2 is enlarged to become subbasin )33 -3 as <br />the final grading is accomplished on the face of the first lift. The rest of <br />subbasin B1 -6 becomes subbasin B3 -1 because the overburden storage area grows to <br />form a drainage divide. Drainage remains directed into the ponds and sumps. At <br />this stage, the existing diversion ditch is terminated upstream of Pond SP -2. <br />This termination allows additional activity in this area. However, the remainder <br />of the diversion ditch remains with its design capacity unaffected. <br />Configuration #4, for a time period sometime in 1999 (approximately), represents <br />the overburden storage area at about the point the second lift has been <br />constructed to its ultimate elevation. At this time, new subbasin B4 - has <br />consumed a number of earlier subbasins such as B3 -1, B3 -2, B1 -1, and B1 -2. <br />Subbasins B1 -4 and B1 -7 remain the same, as does B3 - 3. Runoff remains directed <br />to ponds. <br />Configuration #5, for the year 2000 (approximately), represents the storage area <br />with slope reductions completed up to this point and the surface "topsoiled" and <br />revegetated. The storm -water runoff at this stage of progression and reclamation <br />is considered equivalent to runoff from undisturbed areas. The principal <br />drainage channel, G -H, carries much of the runoff flow, if runoff should occur. <br />Drainage is directed to the current storm -water diversion system located <br />- downgradient of the Arequa Gulch overburden storage area (at and downgradient of <br />the Secondary Crusher area). <br />DRAINAGE - CHANNELS AND STABILITY <br />Mine construction techniques, which include overburden storage area construction, <br />create roadway drainage ditches that are oversized for the flows projected for <br />this area. This large size is a result of crowning the haul roads to drain <br />toward the berms along the side of the roads and the wide width of the blade <br />equipment constructing drainage -ways beside the roads. When riprap is required <br />to maintain stability of the channels, standard run -of -mine rock may be used and <br />this material will also serve as the foundation for many drainage channels, thus <br />negating the need for additional riprap. <br />The computation sheets accompanying this description provide peak discharge <br />computations for the downstream end of the subbasins (which, in all cases, lead <br />to a detention or retention structure that further controls erosion). CC &V has <br />5 <br />