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<br />Where C = the runoff coefficient (dimensionless) <br />i = the rainfall intensity in inches per hour <br />A = the basin area <br />Because the area above the waste rock pile is steeply slopin_ and not <br />well vegetated, a runoff coefficient of 0.60 was selected. <br />In order to divert the runoff from the design storm away fro the waste <br />rock pile, a ditch and culvert system were designed. The di ches <br />will divert runoff from the high ground above the waste rock pile. <br />Two shallow ditches will run parallel to the top of the avast rock <br />pile, and will be dug into the existing terrain. The first itch <br />will direct water which enters the site from the vicinity of the access <br />road (Exhibit C-I). The water will travel along the south s de of the <br />road to a concrete drop box and culvert. The second ditch w 11 divert <br />the remaining water around the west end of the waste rock pi e to the <br />naturally occurring drainage. <br />The culvert will be four feet in diameter and will be constr cted of <br />galvanized corrugated steel. It will run in a northeasterly direction <br />from the drop box underneath the waste pile. The drop box will be lo- <br />cated near the junction of the road and office building. At the down- <br />stream end of the culvert a concrete energy dissipation stru ture will <br />be provided to prevent erosion. The water will then contin a along the <br />natural drainaoe located directly below the portal shown on Exhibit C-1. <br />It should be noted here that the plan described above is deigned to <br />protect the naturally occurring drainages and to prevent ru off from <br />