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DPS: <br />DPS conveys dischazge from channel DS9, located on the Lower Bench. The estimated <br />' discharge is approximately 2.7 cfs with a flow velocity of approximately 6.6 ft/s. The <br />channel slope in DPS is approximately 6 % (S = 0.60) on the north face of the Lower <br />Bench (dump). The estimated riprap size for channel DPS is estimated to be 0.7 ft. <br />Tables 5 and 5.1 show the riprap sizing calculations for DPS. <br />A local source of riprap has been identified near the town of Collbran, Colorado, located <br />' approximately 25 miles to the southeast of the mine. The riprap material consists of <br />rounded basalt and is expected to have a specific gravity of 2.3 to 2.5. <br />' S.0 SCHEDULE <br />Stonnwater control construction is planned for the summer 2005. This work will be <br />followed by the application of soil amendments (future TR) to the benches and some <br />sections of roads and final revegetation of these surfaces. Final pull-back and <br />' reclamation of the main access road is not expected to be conducted until approval of <br />revegetation conditions is obtained by DMG. <br />6.0 REFERENCES <br />Abt, S. R. and T. L. Johnson, 1991. Riprap Design for Overtopping Flow, Journal of <br />Hydraulic Engineering, Vol. 117, No. 8, August 1991, pp. 959-972. <br />ACOE 1994. EMI 110-2-1601, Draft version change 1, U.S. Army Corps of Engineers, <br />June, 1994. <br />Chow, V. T., Maidment, D. R., and L.W. Mays, 1988. Applied Hydrology. McGraw-Hill, <br />Inc. New York. <br />NOAA. 1973. Miller, J.F., Frederick, R.H. <br />Frequency Atlas of Western United States, <br />Atmospheric Administration. <br />and R. J. Tracey, 1973. Precipitation- <br />Volume III, Colorado, National Oceanic and <br />Prather, N. 2004. Personal communication, rancher in Roan Creek Valley. <br />SWMM 1996. Stormwater Management Manual. City of Grand Junction and Mesa <br />County. May. <br />Western Water 8 Land Inc. 16 <br />