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<br />Mr. Luke Russell -3- <br />TABLE 2 <br />BULLDOG MINE <br />OPEN CHANNEL CAPACITY EVALUATION <br />(PMP/100-Year) <br />September 21 1993 <br /> <br /> <br />Location Design <br />Flow <br />(cfs) Channel <br />Slope <br />(ft/ft) Side <br />Slope <br />H:V Bottom <br />Width, <br />(ft) Water <br />Depth, <br />(ft) Average <br />Velocity <br />(ft/s) <br />Upper Tailing Pond 513/3 0.01 1:1 8 4.8/0.2 8.4/1.6 <br />Lower Tailing Pond 650/4 0.01 1:1.5 8 5.4/0.3 9.0/1.8 <br />(2 Diversion <br />Channels) <br />Windy Gulch at 3,549/24 0.10 1:1 4 10.1/0.8 25.0/6.6 <br />Waste Dump 1:1 30 4.4/0.2 23.7/3.5 <br /> 1:2 18 5.5/0.3 22.4/4.2 <br /> 0.25 1:2 18 4.3/0.2 31.2/5.6 <br />• Manning's "n" value of 0.03 and 0.05 were used for evaluation. <br />Conclusions <br />Based on the computed flows, velocities and existing channel configurations, conclusions <br />can be made regarding the capacity and integrity of the existing channels to adequately <br />convey the PMP and 100-year runoff events. <br />Windy Gulch Channel. The Windy Gulch channel should safely convey the 100-year, 24- <br />hour runoff event with minimal upgrading. The tce of the waste dump should withstand <br />erosion resulting from this runoff, given the average size of the waste rock material and <br />computed flow velocities. The channel sideslopes across from the tce of the waste dump <br />should be armored with 6-9 inch mean diameter (based on Ishbash Curve, SCS 1984) <br />angular rock riprap where none presently exists. For this channel to pass the PMP event <br />without significantly eroding the toe of the waste dump would require placement of <br />approximately 60 inch mean diameter (based on Ishbash Curve, SCS 1984) angular rock <br />