West Virginia Code of State Rules › Agency 36 - Coal Mine Health And Safety › Title 36 - LEGISLATIVE EXEMPT RULE BOARD OF COAL MINE HEALTH AND SAFETY › Series 36-41 - Rules And Regulations Governing Requirements For The Use Of Sheathed Explosive Units › Section 36-41-4 - Preparation Of Shots; Blasting Practices And Requirements For Sheathed Explosive Units

Current through Register Vol. XLI, No. 28, July 12, 2024
4.1. Only a
				certified "shot firer" designated by mine management shall be permitted to
				handle explosives and do blasting. Only electric detonators of proper strength
				fired with permissible shot firing units shall be used except under special
				permits as hereinafter provided, and drillholes shall be stemmed with at least
				twenty-four inches on incombustible material, or at least one half of the
				length of the hole shall be stemmed if the hole is less than four feet in
				depth, unless other permissible stemming devices or methods are used.
				Drillholes shall not be drilled beyond the limits of the cut, and as far as
				practicable, cuttings and dust shall be cleaned from the holes before the
				charge is inserted. Charges of explosives exceeding one and one half pounds,
				but not exceeding three pounds, shall be used only if drillholes are six feet
				or more in depth. Ample warning shall be given before shots are fired, and care
				shall be taken to determine that all persons are in the cleat before firing.
				Miners shall be removed from adjoining places and other places when there is
				danger of shots blowing through. Shots shall be fired in any place known to
				liberate explosive gas, until such place has been properly examined by a
				competent person who is designated by mine management for that purpose, and no
				shots shall be fired in any place where gas is detected with a permissible
				flame safety lamp until such gas has been removed by means of ventilation.
				After firing any shot, or shots, the person firing the same shall not return to
				the working face until the smoke has been cleared away and then he shall make a
				careful examination of the working face before leaving the place or before
				performing any other work in the place.
4.2. Multiple shooting in coal or rock or
				both is authorized only under permit issued by the director. Permission to
				shoot more than ten shots simultaneously may be granted by the director only
				after consultation with interested person, and the deputy director of safety,
				health and training, and such shooting will be performed by special methods and
				under precautions prescribed by the director. All multiple shooting in bottom
				or roof rock shall be performed in intake air, except by special permit from
				the director, after consultation with interested persons and the deputy
				director of safety, health and training, as hereto provided. Multiple blasting
				of more than ten shots performed under any permit granted by the director under
				this section shall be done only on noncoal-producing shifts or idle days,
				except as may be provided as a condition of the permit granted.
4.3. Regular or short-interval delay
				detonators may be used for blasting purposes with written permission from the
				director after consultation with the deputy director of safety, health and
				training. Regular delay detonators shall no be used for blasting coal, but may
				be used for grading above or below coal seams and during shaft, sloap, tunnel
				work and in faults or wants. Where short-interval delay detonators are
				permitted by said directors to be used, the shot firing circuit must be tested
				with a blasting galvanometer before firing, and the leg wires connected in
				series. No instantaneous, regular, or zero-delay detonators are to be fired in
				conjunction with short-interval delay detonators. The delay interval between
				dependant rows must not be less than twenty-five milliseconds or more than one
				hundred milliseconds, and the entire series on any one round shall not provide
				a delay of more than five hundred milliseconds between the first and last shot.
				The total number of charged holes to be fired during one round must not exceed
				the limit permitted by the director. Misfires must be tested with a blasting
				galvanometer before removing.
4.4.
				Electrical equipment shall not be operated in the face areas, and only work in
				connection with timbering and general safety shall be performed in connection
				with timbering and general safety shall be performed while boreholes are being
				charged. Shots shall be fired promptly after charging. Mudcaps (adobes) or any
				other unconfined shots shall not be permitted in any coal mine. No solid
				shooting shall be permitted without written permission of the
				division.
4.5. Blasting cables
				shall be well insulated and shall be as long as may be necessary to permit
				persons authorized to fire shots to get in a safe place out of the line of
				fire. The cable, when new, shall be at least one hundred twenty-five feet in
				length and never less than one hundred feet. Shooting cables shall be kept away
				from power wires and all other sources of electric current, connected to the
				leg wires by the person who fires the shot, staggered as to length or well
				separated at the detonator leg wires, and shunted at the battery until ready to
				connect to the blasting unit.