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'there are 5 ditches used for isolation. 'the collection ditches mill be V-ditches of 1.5 feet depth <br />and 2H:1 V side slopes cut out of the natural gravel. In most areas no lining will be needed due to <br />the mild slopes of the site. Where ditches encounter steep grades, arip-rap lining will be used. <br />Ditch # J controls water entering into the South Pit from the west. The water from this ditch will <br />be channeled to the unnamed natural drainage to the southwest of the permit area. Ditch #2 drains <br />the next most northern azea. Due to topography, the ditch will feed a pipe at its low point which <br />will skirt above the west cut slope of the well pad. This.pipe will direct the runoff into the major <br />drainage that will pass through the mine site near its center. 't'he large gaily currently in this loca- <br />tion will be slowly filled during the pit's life using naturals produced by the- crushing/screening <br />process. To facilitate drainage after mining a storm water channel will be installed. The design of <br />the channel can be seen below. Ditches #3 and #4 provide isolation for 213 of the Northern pit <br />They direct water flow into the same drainage as Ditch #2. Ditch #5 completes the isolation of the <br />northern pit and redirects the water to the north into another natural drainage. Ditches #6 and 7 <br />complete the isolation of the South pit Area 5 and redirect the water to into another natural drain- <br />age. <br />The pit bottom will serve as the containment basin for the operation. All water will be contained <br />from a 100-year event and allowed to evaporate or seep out during a 72-hr or longer period. The <br />drainage basin area is the entire permit area. 't'he precipitation of a 100-year event is 3.2 inches. <br />The isolation berms surrounding the site will be 3 feet in height with 2H:1 V slopes, with a primaz- <br />ily flat pit floor. This will provide more than sufficient storage fora 100-year event. Because the <br />pit will contain al] runoff from a 7'00-year storm no dischazge permit is required: Berms will also <br />be built to isolate the grass lined channels which are being built in the valley fill areas. During <br />construction of the valley fills, an isolation berm will be built at the mouth of the each valley. <br />This berm stop the sediment flow from leaving the permit area. <br />Cugnini 12103 11 <br />