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drainage management features for the operations area are designed for near zero discharge. The only <br />exception to this will be the down slope sides of the over burden stock piles placed along the eastern side <br />of the mine site. For these sloped faces, silt transfer will be managed using waddles, silt fences, straw <br />bails, rock check dams, or other similar erosion and silt control measures. <br />The drainage considerations for the operational site, assumes that the current grading of the site would not <br />be altered in any significant manner, except as necessary to ensure that drainage water from the <br />operational site is not allowed to leave the site. The site will be graded to contain all drainage water and is <br />depicted in Figure 6 -Mine Operation Area. The Operation Area, as depicted, includes the entrance to the <br />mine, i.e. the mine portal, the ore stockpile pad, over burden stockpile areas, staging areas, vehicle <br />maneuvering areas, storage areas, access road into the site, and 5 retention ponds for managing the <br />stormwater runoff. The general use of the surface area in the operation area will not have significant use <br />changes; however, as the mine's operation is continued, the stockpiles will be enlarged and the ore pile <br />will fluctuate in size as the ore is mined and removed from the site. <br />In accordance with the Manual, the recommended imperviousness values provided in Figure 26.28.020(a) <br />of the Manual were used. Imperviousness for Area 1, i.e. the undeveloped area of the mine, was assumed <br />to be 2 %, and the imperviousness for Area 2, the Operations Area, was assumed to be 15 %. The "C" <br />coefficients used in the Rational Formula were derived from Table 26.28.020 of the Manual. The <br />corresponding Runoff Coefficients, C, for the various return storm events was interpolated assuming the <br />"Impervious Decimal" of Table 26.28.020 of 0.02 for the undisturbed area, Area 1, and .15 for the <br />Operational Area, Area 2, for Type C and D Soil. <br />Entrance Road Analysis <br />The analysis of the entrance road began with the identification of the grading conditions of the roadway. <br />The grading conditions of the roadway were identified as crowned or cross - sloped. The limits of each <br />grading condition, i.e. where the grading condition started and stopped, were identified. The drainage <br />areas contributing to each section was delineated and the parameters of each identified basin were then <br />determined. The parameters determined included the area of the basin, the flow length of the basin, and <br />the average slope of the basin from the top to the bottom, i.e. where the drainage basin met the roadway <br />alignment. These parameters were in addition to the earlier described parameters of soil types, rainfall <br />data, vegetation cover, etc. See Figures 4 and 5 for drainage basin delineation/configurations. <br />Using the Rational Method of analysis, a peak runoff rate for the l0 -year, 25 year, 50 year, and 100 year, <br />24 hour rainfall event, was calculated. The results of runoff analysis are summarized in Table 1 -Peak <br />Runoff Analysis Summary for Access Road. Computer modeling spreadsheets for the analysis are <br />presented in Appendix 2 identified as Basins I through 13. <br />16 <br />