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METHODS OF MINING - <br />• Open Pit - Mining of the open pit is done by drilling and <br />blasting 10 to 30 foot thick benches. This is accomplish=_d typically <br />by loading the drill holes with ammonium nitrate. The holes are detonated <br />in pairs separated by millisecond delays. The use of the delays <br />minimizes the shocY, and noise effects. <br />After the rock has been blasted it is loaded ini:o trucks with <br />a front-end loader and hauled to the processing plant. <br />The result of this method is to ultimately produce, in most <br />cases, terraces about 15± 3 feet wide and 25+ feet high. On terraces <br />~+here ad its would be constructed the terrace will be approximately 50 <br />feet wide to accomodate equipment movement in and out of t:he portals. <br />Underground Mining - Adits are constructed in pairs so the <br />• drilling and blasting crews can work in one while material from the <br />other is being removed. There currently are two portals to two <br />horizontal adits on the west side of the open pit. During non-working <br />hours these have wire doors that are closed and locked to prevent any <br />unauthorized entry. Mining underground is done by means of conventional <br />room and pillar methods. No roof support between pillars is needed as <br />the integrity of the limestone is such that caving is nearly impossible. <br />This great integrity is also the reason why subsidence of adjacent <br />lands is of no concern at all. The limestone is simply so strong caving <br />to the surface would not occur for perhaps thousands of years if ever. <br />CON~TRUCTIOPI OF TFE BERM - The noise and sight barrier be nn is <br />constructed of limestone fine' materials dumped on the area and compacted <br />to 75~ to 90€ with equipment running over the material several times. <br /> <br />S-D-4 <br />