Laserfiche WebLink
JD-8 Mine - Drainage Design Plan 3 <br />• Some areas above the Lower Mine Permit Area may contribute runoff onto the mine site during extreme <br />storm events. Specifically, the area below the road leading up to the water tank (Figure 2) would runoff <br />onto the mine site if a major storm occurred under current site conditions. Areas that would contribute run- <br />on to the site are shown in Figure 2 and Table 2. <br />Stormwater runoff at the mine occurs from both disturbed and undisturbed areas. Runoff from undisturbed <br />areas is considered "non-contact" stormwater because it has not had potential exposure to industrial <br />pollutants (roof runoff, access roads, employee parking areas, waste rock piles, etc). The fuel storage area <br />is bermed and lined, and does not contribute stormwater to any catchment onsite. As shown in Figure 2, <br />drainage areas have been divided into four runoff zones and two receiving zones. Surface flow from <br />undisturbed runoff zone 1 and disturbed runoff zone 2 is routed to receiving zone 3, near the topsoil <br />stockpile. Similarly, surface flow from undisturbed runoff zone 4 and disturbed runoff zone 5 is routed to <br />the constructed catchment in receiving zone 6. <br />Drainage at the site is controlled by the ditches, berms, culverts, and topography. The eastern portion of <br />the waste rock pile is sloped gradually westward. Runoff from undisturbed areas above the mine (Zone 4, <br />acres) and disturbed areas associated with the access road, ore storage area, and a portion of the eastern <br />waste rock pile (Zone 5, acres) are routed to the constructed catchment (Zone 6, acres). Runoff is <br />controlled by a berm along the crest of the waste rock pile (Photo 2). The crest berm prevents erosion of <br />the face of the pile, and diverts water along the top of the pile (westward) to a constructed notch in the <br />berm, where water is routed down the face of the waste rock pile to the constructed catchment. <br />A portion of the western waste rock pile area (on which the mine facilities have been constructed) slopes <br />westward toward receiving area 3 (Figure 2). A berm along the crest of the waste rock pile prevents runoff <br />from eroding the face of the pile. Photo 3 shows a former rivulet that developed into a small gully on the <br />• face of the pile, and was then mitigated by repairing the berm along the crest of the waste rock pile. <br />Table 2. Drainage Basin Areas at the JD-8 Mine under Current Conditions <br /> Area Area <br />Zone (ft2) (acres) Type <br />1 37,010 0.85 Non-contact area (undisturbed) <br />2 28,590 0.66 Disturbed area <br />3 33,100 0.76 Receiving area (near soil stockpile) <br />4 87,730 2.01 Non-contact area (undisturbed) <br />5 142,470 3.46 Disturbed area <br />6 8,050 0.18 Receiving area (Constructed Catchment) <br />• <br />4122A.110601 Whetstone Associates