2012-09-05_REVISION - M1995030 - Laserfiche WebLink

Home Browse Search

MINING PLAN EXHIBIT D (cont) to them being install on the mine site if ever. The existing access road that enters the Plant Site from the west property line will be used for ingress and egress. As mining progresses around the property the ban]. slopes will be created in two stages. When a dredge is used materials tend to sluff off the banks and assume an a repose of 2'h to lv. This happens because the materi the native gle of 1 in this area is unconsolidated and vertical slopes can not be maintained as mining occurs. This means that to maintain a setback of 25 feet from the permit line when the gravel is 60 feet thick the mining line has be no less than 75 feet inside the setback lines to allow for the sloughing. The final sloping will be done by pumping material onto the slopes or using a dozer to push surface material into the lake to establish the 3h to lv slopes. The dredging operation will include the use of explosives as described below. The explosives will not be used to extract material, only to relieve unsafe conditions caused by the method of mining used at the site. During dredging the operator works across the mine face from left to right and top to bottom. This creates an undercut on the mine face that normally caves off and is removed from the bottom of the lake by the dredge. As the surface is approached the thickness of the overhang decreases and a point is reached where it no longer breaks off due to its own weight. This leaves an unsafe condition where there is the potential for personnel or equipment to enter the overhang area, cause it to slough off carrying them into the water and burying them. To alleviate this problem a light charge is set qff to drop the overhang into the lake leaving the slope at it natural angle of repose. Once mining ends, this same method is used to stabi- lize the working face and stay in compliance with our MSHA permit. The practice of using explosives to stabilize the cut face is a standard practice on any mine where we operate. Under normal conditions a charge will be set off once or twice during a mining period and that will occur every 2 to 4 years depending on the demand for material. The method used will involve hiring a registered blasting contractor to determine the size of the charge needed to stabi- lized the cut face (usually a quarter ( stick of dynamite). The method for placing the charge is to put the dynamite in a plastic jug, sink it next to the overhang and detonate the charge. The blasting contractor will supply the blasting agent 10