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<br />-IS- <br />• <br /> <br />The collector ditch for the pond at the waste disposal sit= will be stable under <br />flows from the 10-year, 24-hour event 'and the emergency spillway will be stable <br />during flows resulting from the 25-year, 24-hour event. As in the case for the <br />pond at the mine bench, no mechanical installation is proposed For the dewatering <br />of the pond down to the maximum sediment storage Zeve1. <br />The following stipulation is required for a finding of compliance: <br />Stipulation No. 2 <br />WITHIN SIX MONTRS OF PERMIT ISSUANCE AND PRIOR TO CONSTRUCTION OF <br />THE SEDIMENT PONDS AT THE MINE BENCH AND AT THE WASTE DISPOSAL SITE, <br />TXE PERMITTEE ;9UST INSTALL APPROVED DEWATERING DEVICES TO DEWATER <br />THE PONDS TO THE MAXIMUM SEDIMENT sTORAGc- LEVEL. ALSO, TXE <br />PERMITTEE MUST COMMIT TO INSTALLING MARXERS TO INDICATE TXE 60° <br />SEDII~fENT STORAGE LEVEL AT BOTH SEDIMENT PONDS. <br />The bypass culvert conveying undisturbed flow beneath the mine bench fill is <br />sufficient to pass the required 10-year, 24-hour peak flow. Velocities of <br />water discharged from the cvlrert during the 10-year, 24-hour event will be <br />moderat°. Since the applicant proposes to install a dumped rock gutter at the <br />discharge end of the culvert, the energy should be properly dissipated. <br />The bypass culvert will discharge into a riprap-lined temporary di m rsion which <br />will convey the flow into the natural drainage. 3ecause of the high slope of <br />the channel, flow velocities during tF.e 10-year, 24-hour event could Se as <br />high as 16 feet per second. The applicant has corJrtitted to the installation <br />o_° adequate channel lining to inhibit erosion of the diversion and appropriate <br />measures to dissipate flow energy prior to discharge into the receiving <br />drainage. <br />The collection ditches and culverts conveying runoff from the disturbed area <br />at the mine bench rill adequately carry the flow resulting from the 10-year, <br />24-hour event. Ditches collecting disturbed flow and diverting undisturbed <br />flow at the waste disposal site will also be stable under the 10-year, 24-hour <br />peak flow conditions. .These components of the surface drainage system are in <br />compliance with ~4e Rules and Regulations. <br />YI. Hydrologic Balance: Cround Water - Rules 2.04.5, 2.04.7, <br />2.05.6(3) and 4.05 <br />Information provided by the applicant with respect to c:round water in the permit <br />area can be _`ound in Sections 2.3.2, 2.6, and 4.~1 in ''JOiume of the appli- <br />cation. Based on an analysis or these data and inr.'ormation, [he following <br />determinations .lave been made by the Di vz si on. <br />Dr"Sinn i.n the area indicates the presence of a saturated zone :/ithin t5e <br />Cameo seam (Ficure 4.4-:). TI-.is sa taro red zone occurs outside of c.'^s ~e rrnit <br />area within tie '!cClane Canyon :fine plan area and will not he encounc_r_d by <br />projected .Wining wit,v.^ the '4uneer Canyon '9ine. Data L~dicates t:~at .he <br />Ca rbonera seam, wtich ove riles the r_a meo seam, also becomes pro gressz~;e1~ <br />• <br />