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- 6 - <br />• largest for the project. The cr~bankment is constructed for t`~e rost <br />part in the valley of Hayden Gulch an: inpounds a small tributary <br />drainage to that gulch. Fig. 3B shows a Generalized profile along the <br />centerline. It will have a crest length of aoproxi;^ately 1300 feet and <br />a maximum height of about 40 feet. This will ae the first dam to be <br />cr~nstructed are9 receives drainage from one of the first mined areas. <br />Fig. 1 shows surface drainage boundaries for the five pond areas. <br />urainaye fray the .mina; area will parallel Hayden Gulch arr3 Fe diverted <br />into the dam at its northern err_~. Hayden Gulch will be channelized <br />between the downstreaa toe of the dam and the existing County Foal. <br />The dam dill have an i;~ooundmznt caracity of 31.4 acre feet at the <br />proposed spillway elevation of 7319. <br />• of sediment storage will tc allowed. <br />elevation at 7306 is oroposed on the <br />spillway will also pe located at Sta <br />er.,banlener.t. <br />l feet. Approximately 4 acre feet <br />A<i outlet marks with its invArt <br />sout!i end cf the et'Lhanlv'~en*_. F. <br />,, <br />. 2+00 near th~a south end of the <br />P. typical proposed section of th^ cam is sho:.•n on Fig. 3A. ':his <br />section inwrporates 3:1 slopes upstream and downstreas~ anti has a <br />13-fcot crest width. A nominal cutoff is proposed to key the dam into <br />the existing soils. It is also anticipated that rer;ioval of soft and <br />organic soils beneath the dam will be rec*uired during e~nstcuction. <br />'iS~e embankment is essentially a modified hanogereous one. Selective <br />material placement will consist of the clay and claystone placed in the <br />center and upstream portion and coarser sandstone on the,da+nstream <br />portion. Cor~eaction will be to 93~ ~:iodified Proctor density. On the <br />• downstream toe, a blanket arc] toe underdrain systt~r have been provi•9ed. <br /> <br />