PERMFILE47760 - Laserfiche WebLink

Home Browse Search

2.2 Blasting Activities Following the completion of topsoil stripping in Colt Pit, overburden blasting will commence. Blasting procedures as outlined in Section 3.4 of Trapper's Mining and Reclamation Permit will be followed. Most of the area to be blasted in 1987 will occur within a horizontal distance of 800 feet from the underground workings of Empire Energy Corporation's Eagle No. 5 Mine. Map PR1-1 shows the area to be blasted and Empire's underground workings [hat lie within the 800-ft horizontal distance of the blasting area. The underground workings shown are mostly abandoned room and pillar areas for which an estimated 85% extraction was accomplished. No currently active head- ings fa 11 within the 500 horizontal feet of [he planned blasting area. Trapper is requesting a variance from the 500 horizontal foot limit for sur- face coal mining over an active or abandoned underground mine. Safety of the underground workers will not be compromised as more than 800 vertical fee[ shall separate the two mines. Trapper will blast within 500 horizontal feet of Empire's East Main Extension, 4th East Panel, 1st Left Panel and 2nd Left Panel, Map PR1-1. Pillar strength calculations as shown in Empire Energy's Eagle No. 5 Mine Permit show minimum pillar sizes required for a 1.5 to 2.0 safety factor to be 40-ft x 40-ft pillars in the East Main Extension and 42-ft x 42-ft pillars in 4th East Panel, 1st Lef[ Panel and 2nd Left Panel. Minimal pillar sizes le f[ in place for the Main East Extension are 50-ft x 50-ft, resulting in a cross-sectional pillar area of 900 additional feet of. pillar, 56 percent more pillar than required for a safety factor of 1.5 or 2.0. Minimum pillar sizes left in place for the 4th East Panel are 50-ft x 50-ft, resulting in a cross-sectional pillar area of 736 additional fee[ of pillar, 42 percent more pillar than required for a safety factor of 1.5 or 2.0. Pillar retreat mining methods have been used in [he 1st Lef[ Panel, thus most pillars have been removed and the area caved. Minimum pillar sizes left in place for the 2nd Lef[ Panel are 30-f[ x 120-f[, resulting in a cross-sectional pillar area of 1,836 additional feet of pillar, 104 percent more pillar than required for a safety factor of 1.5 to 2.0.