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<br />Nuvemco Monogram Mine SWMP <br />and Loading Area will be diverted into an underground holding tank. The holding tank <br />design and specifications are not part of this study. <br />Deducting the Ore Bin and Loading Area the net area contributing to the detention pond <br />at the northeast corner of the site will be 29,547 sq ft or 0.68 acres. <br />PEAK RUNOFF <br />There are several methods that can be used to compute the peak runoff from the area. <br />The size of the area is such that many of the methods are not suitable for such a small <br />area. The Rational Method is suitable for areas up to 140 - 160 acres. The Rational <br />Method was selected where: <br />Q=CiA <br />Q = peak discharge cubic feet per second (cfs), <br />C = Rational Method runoff coefficient <br />i = rainfall intensity, inches/hour <br />A = Area, acres <br />The staging area is a single basin with no sub-basins. All flow will be overland with no <br />channel flow. <br />C - Rational Method Runoff Coefficient <br />From Photograph 9, the area has been cleared of almost all of the vegetation. The area <br />has been described as mostly rock with little, if any infiltration. The equipment will also <br />compact the area and reduce infiltration. Therefore the coefficient, C, will be high. From <br />different tables available to estimate the coefficient will be approximately 0.95. <br />i - Rainfall Intensity <br />The Nuvemco Monogram mine is located in Hydrologic Zone 2, San Juan, Upper Rio <br />Grand, Upper Colorado, and Gunnison River Basins, and Green River Basin below <br />confluence with the Yampa River in the State of Colorado. <br />From the NOAA ATLAS 2, Volume III Figures 22 through 31 the precipitation for <br />various storms can be estimated in tenth inch. The estimates, based on the site latitude <br />and longitude, are as follows: <br />DURATION <br /> 6-HR 24-HR <br />FREQUENCY (INCHES) (INCHES) <br />2-YR 0.9 1.2 <br />5-YR 1.2 1.6 <br />10-YR 1.35 1.95 <br />25-YR 1.6 2.4 <br />2