Administrative Rules of Montana › Department 17 - ENVIRONMENTAL QUALITY › Chapter 17.24 - RECLAMATION › Subchapter 17.24.1 - Rules and Regulations Governing the Montana Hard Rock Mining Reclamation Act › Rule 17.24.159 - BLASTING OPERATIONS: ORDERS OF THE DEPARTMENT

Current through Register Vol. 13, July 5, 2024
(1) If the department determines that the
				preponderance of evidence indicates that property damage or safety hazards are
				or were caused by blasting associated with exploration or mining activities by
				an operator, the department shall issue an order. In the event the order is not
				complied with, the department shall issue an order imposing requirements
				reasonably necessary to prevent property damage or safety hazards.
(2) The department may require as many of the
				following requirements as are reasonably necessary for this purpose:
(a) Each operator shall comply with all
				applicable state and federal laws in the use of explosives.
(b) All blasting operations must be conducted
				by experienced, trained, and competent persons who understand the hazards
				involved.
(c) A record of each
				blast occurring over a period to be determined by the department, including
				seismograph records, must be prepared and retained for at least three years and
				must be available for inspection by the department on request. Blasting records
				must be accurate and completed in a timely fashion. The records must contain
				the following data:
(i) name of the operator
				conducting the blast;
(ii)
				location, date, and time of the blast;
(iii) name, signature, and, if applicable,
				license number and appropriate certification program name of
				blaster-in-charge;
(iv) direction
				and distance, in feet, to the nearest inhabited building or structure either:
(A) not located in the permit area;
				or
(B) not owned nor leased by the
				person who conducts the mining activities;
(v) weather conditions, including
				temperature, wind direction and approximate wind velocity;
(vi) type of material blasted;
(vii) number of holes, burden, and
				spacing;
(viii) diameter and depth
				of holes;
(ix) types of explosives
				used;
(x) total weight of
				explosives used;
(xi) maximum
				weight of explosives detonated within any eight-millisecond period;
(xii) maximum number of holes detonated
				within any eight-millisecond period;
(xiii) initiation system;
(xiv) type and length of stemming;
(xv) mats or other protections
				used;
(xvi) type of delay detonator
				and delay periods used;
(xvii)
				sketch of the delay pattern;
(xviii) number of persons in the blasting
				crew;
(xix) seismographic and
				airblast records, where required, including:
(A) the calibration signal of the gain
				setting or certification of annual calibration;
(B) seismographic reading, including exact
				location of seismograph and its distance from the blast, airblast reading,
				dates and times of readings;
(C)
				name of the person taking the seismograph reading; and
(D) name of the person and firm analyzing the
				seismographic record.
(d) When blasting is conducted in an area
				where access is not restricted, warning and all-clear signals of different
				character that are audible at all points within a range of 1/2 mile from the
				point of the blast must be given. Each person within the permit area and each
				person who resides or regularly works within 1/2 mile of the permit area must
				be notified of the meaning of the signals through appropriate instructions.
				These instructions must be periodically delivered or otherwise communicated in
				a manner that can be reasonably expected to inform such persons of the meaning
				of the signals.
(e) Blasting must
				not eject flyrock off property controlled by the operator. Access to the
				blasting area and to areas where blasting effects, such as flyrock, occur, must
				be controlled by methods such as signs and fencing to prevent the presence of
				livestock or unauthorized personnel during blasting and until an authorized
				representative of the operator has reasonably determined:
(i) that no unusual circumstances, such as
				imminent slides or undetonated charges, exist; and
(ii) that access to and travel in or through
				the area can be safely resumed.
(f) The operator shall comply with the
				following to control airblast:
(i) Airblast
				must be controlled so that it does not exceed the values specified below at any
				dwelling, public building, school, church, or commercial, public, or
				institutional structure, unless the structure is owned by the operator and is
				not leased to any other person. If a building owned by the operator is leased
				to another person, the lessee may sign a waiver relieving the operator from
				meeting the airblast limitations of this section.
_________________________________________________________________
Lower Frequency limit of
measuring system, Hertz (Hz)
							 (+3dB)
Maximum level in
decibels (dB)
0.1 Hz or lower - flat response
							 .........................................
134 peak.
2 Hz or lower - flat response
							 ............................................
133 peak.
6 Hz or lower - flat response
							 ............................................
129 peak.
C-weighted, slow response
							 .............................................
105 peak dBC.
If necessary to prevent damage based upon the consultant's
				  report, the department shall specify lower maximum allowable airblast levels
				  than those above.
_________________________________________________________________
(ii) In all cases, except the C-weighted,
				slow-response system, the measuring systems used must have a flat frequency
				response of at least 200 Hz at the upper end. The C-weighted system must be
				measured with a Type 1 sound level meter that meets the standard American
				National Standards Institute (ANSI) S 1.4-1983 specifications. These
				specifications are incorporated by reference. Copies of this publication are on
				file with the Department of Environmental Quality, P.O. Box 200901, Helena, MT
				59620-0901.
(iii) The operator may
				satisfy the provisions of this subsection by meeting any of the four
				specifications in the chart in (i).
(iv) The operator shall conduct periodic
				monitoring to ensure compliance with the airblast standards. The department may
				require an airblast measurement of any or all blasts, and may specify the
				location of such measurements, except as noted in (i).
(g) Whenever the standards contained in (k)
				(i) and (o) (iii) have been exceeded, or whenever, based upon the consultant's
				report, it has been determined to be necessary to protect public safety or
				property, the department may require modification of blasting activities to
				protect:
(i) public, private or institution
				building, including any dwelling, school, church, hospital, or nursing
				facility; and
(ii) facilities
				including, but not limited to, disposal wells, petroleum or gas storage
				facilities, municipal water storage facilities, fluid transmission pipelines,
				gas or oil collection lines, or water and sewage lines or any active or
				abandoned underground mine.
(h) A blast design, including measures to
				protect the facilities in (g) must be submitted to the department prior to
				continued blasting.
(i) Flyrock,
				including blasted material traveling along the ground, must not be cast from
				the blasting vicinity more than half the distance to the nearest dwelling or
				other occupied structure and in no case beyond the line of property owned or
				leased by the permittee, or beyond the area of regulated access required under
				(e).
(j) Blasting must be conducted
				to prevent injury to persons, damage to public or private property outside the
				permit area, adverse impacts on any underground mine, and change in the course,
				channel, or availability of ground or surface waters outside the permit
				area.
(k)
(i) In all blasting operations, except as
				otherwise authorized in this subsection, the maximum peak particle velocity
				must not exceed the following limits at the location of any dwelling, public
				building, school, church, or commercial, public, or institutional structure:
_________________________________________________________________________________________
Distance (D) from the blasting site, in
							 feet
Maximum allowable peak particle velocity (V max) for
							 ground vibration, in inches/second
Scaled-distance factor to be applied without seismic
							 monitoring (Ds)
0 to 300
1.25
50
301 to 5,000
1.00
55
5,001 and beyond
0.75
65
__________________________________________________________________________________________
(ii) Peak particle
				velocities must be recorded in three mutually perpendicular directions. The
				maximum peak particle velocity is the largest of any of the three
				measurements.
(iii) The department
				shall reduce the maximum peak velocity allowed if a lower standard is required,
				based upon the consultant's report, to prevent damage or to protect public
				safety because of density of population or land use, age or type of structure,
				geology or hydrology of the area, frequency of blasts, or other
				factors.
(l) If blasting
				is conducted in such a manner as to avoid adverse impacts on any underground
				mine and changes in the course, channel, or availability of ground or surface
				water outside the permit area, then the maximum peak particle velocity
				limitation of (k) does not apply at the following locations:
(i) at structures owned by the operator and
				not leased to another party; and
(ii) at structures owned by the operator and
				leased to another party, if a written waiver by the lessee is submitted to the
				department prior to blasting.
(m) An equation for determining the maximum
				weight of explosives that can be detonated within any eight-millisecond period
				is in (n). If the blasting is conducted in accordance with this equation, the
				peak particle velocity is deemed to be within the limits specified in
				(k).
(n) The maximum weight of
				explosives to be detonated within any eight-millisecond period may be
				determined by the formula
W=(D/Ds) 
				  2 where W=the maximum weight of
				  explosives, in pounds, that can be detonated in any eight-millisecond period;
				  D=the distance, in feet, from the blast to the nearest public building or
				  structure, dwelling, school, church, or commercial or institutional building or
				  structure, except as noted in (l); and Ds=the scaled distance factor, using the
				  values identified in (k).
(o)
(i)
				Whenever a seismograph is used to monitor the velocity of ground motion and the
				peak particle velocity limits of (k) are not exceeded, the equation in (n) need
				not be used. If that equation is not used by the operator, a seismograph record
				must be obtained for each shot.
(ii) The use of a modified equation to
				determine maximum weight of explosives per delay for blasting operations at a
				particular site may be approved by the department, on receipt of a petition
				accompanied by reports including seismograph records of test blasting on the
				site. The department may not approve the use of a modified equation if the peak
				particle velocity for the limits specified in (k) are exceeded, meeting a 95%
				statistical confidence level.
(iii)
				The operator may use the ground vibration limits in Figure 1 (30 CFR
				816.67 (d) (4)) as an alternative to (i) and
				(ii), upon approval by the department.
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(iv) The department may require a seismograph
				record of any or all blasts and may specify the location at which the
				measurements are to be taken.