Administrative Rules of Montana
Department 17 - ENVIRONMENTAL QUALITY
Chapter 17.24 - RECLAMATION
Subchapter 17.24.6 - Strip and Underground Mine Reclamation Act: Transportation Facilities, Use of Explosives, and Hydrology
Rule 17.24.624 - SURFACE BLASTING REQUIREMENTS
Current through Register Vol. 6, March 22, 2024
(1) The department may limit the area covered, timing, and sequence of blasting, if such limitations are necessary and reasonable in order to protect the public health and safety or welfare.
(2) All blasting must be conducted between sunrise and sunset except that:
(3) Blasting must be conducted at times announced in the blasting schedule, except in those unavoidable hazardous situations, previously approved by the department in the permit application, whenever operator or public safety require unscheduled detonation. Any deviation from the times announced must be reported to the department not later than three days after the unavoidable blast. A complete description of the unavoidable hazardous situation must accompany the report.
(4) Warning and all-clear signals of different character that are audible 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. The operator shall maintain signs in accordance with ARM 17.24.524.
(5) Access to an area possibly subject to flyrock from blasting must be regulated to protect the public and livestock. Blasting must not eject flyrock onto property outside the permit area. Access to the area must be controlled to prevent the presence of livestock or unauthorized personnel during blasting and until an authorized representative of the operator has reasonably determined:
(6)
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, the department shall specify lower maximum allowable airblast levels than those above.
(7) Except where lesser distances are approved by the department, based upon a preblasting survey, seismic investigation, or other appropriate investigation, blasting must not be conducted within:
(8) If otherwise approved, a blast design, including measures to protect the above facilities, must be submitted which contains the information required in ARM 17.24.310 and signed by a certified blaster.
(9) 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 (5).
(10) 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.
(11) In all blasting operations, except as otherwise authorized in this section, the maximum peak particle velocity must not exceed the following limits at the location of any dwelling, or public, commercial, community or institutional building:
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 |
(12) 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 (11) does not apply at the following locations:
(13) An equation for determining the maximum weight of explosives that can be detonated within any eight-millisecond period is in (14). If the blasting is conducted in accordance with this equation, the peak particle velocity is deemed to be within the limits specified in (11).
(14) 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 hole nearest to a dwelling, or public, commercial, community or institutional building, except as noted in (12); and Ds = the scaled distance factor, using the values identified in (11).
AUTH: 82-4-205, MCA; IMP: 82-4-231, MCA