Section 69-05.2-17-05 - Performance standards - Use of explosives - Surface blasting procedures1. All blasting must be conducted between sunrise and sunset, unless nighttime blasting is approved by the commission upon a showing by the operator that the public will be protected from adverse noise and other impacts. The commission may specify more restrictive time periods for blasting. 2. Blasting must be conducted at the scheduled times, except in those unavoidable hazardous situations, previously approved by the commission in the permit application, where operator or public safety require unscheduled detonation. 3. Warning and all-clear signals of different character that are audible within a range of one-half mile [0.85 kilometers] from the point of the blast must be given. Each person within the permit area and each person who resides or regularly works within one-half mile [0.85 kilometers] of the permit area must be notified of the meaning of the signals through appropriate instructions. Recipients must be periodically and clearly informed of the meaning of the signals. Signs must be maintained according to subsection 6 of section 69-05.2-13-04. 4. Access to an area possibly subject to flyrock from blasting must be regulated to protect the public and livestock. 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 that: a. There are no unusual circumstances, such as imminent slides or undetonated charges; and b. Access to and travel in or through the area can be safely resumed. 5. Airblast must be controlled so that it does not exceed the values in this subsection at any dwelling, public building, school, church, or commercial or institutional structure, unless the structure is owned by the operator or permittee and is not leased to any other person. If a building owned by the operator or permittee is leased to another person, the lessee may sign a waiver relieving the operator from meeting the airblast limitations of this subsection. | Lower frequency limit of measuring system, Hz (plusmn;3dB) | Maximum level in 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. |
a. In all cases except the C-weighted, slow response, the measuring systems used must have a flat frequency response of at least two hundred Hz at the upper end. The C-weighted case must be measured with a type 1 sound level meter that meets the standard American national standards institute (ANSI) S1.4-1971 specifications. b. The person who conducts blasting may satisfy the provisions of this subsection by meeting any of the four specifications in the chart in this subsection. c. The operator shall conduct periodic monitoring to ensure compliance with the airblast standards. The commission may require an airblast measurement of any or all blasts, and may specify the location of the measurements. d. If necessary to prevent damage, the commission will specify lower maximum allowable airblast levels than those of this subsection for use in the vicinity of a specific blasting operation. 6. Flyrock, including blasted material traveling along the ground, may 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 subsection 4. 7. Ground vibrations. a. In all blasting operations, except as authorized in subdivision e, the maximum ground vibration may not exceed the values approved in the blasting plan. The maximum ground vibration for structures listed in subdivision b must be established according to the maximum peak particle velocity limits of subdivision b, the scaled-distance equation of subdivision c, or by the commission under subdivision d. All structures in the vicinity of the blasting area not listed in subdivision b must be protected from damage by a maximum allowable limit on the ground vibration, submitted by the operator in the blasting plan and approved by the commission. b. The maximum ground vibration may not exceed the following limits at the location of any dwelling, public building, school, church, or community or institutional building outside the permit area. | Distance (D), from the blasting site, in feet | Maximum allowable peak particle velocity (Vmax) for ground vibration, in inches/second | Scaled-distance factor to be applied without seismic monitoring (Ds) |
| 0 to 300 | 1.25 | 50 |
| 301 to 5000 | 1.00 | 55 |
| 5001 and beyond | 0.75 | 65 |
A seismographic record must be provided for each blast.
c. Scaled-distance equation. (1) An operator may use the scaled-distance equation, W=(D/Ds)2, to determine the allowable charge weight of explosives to be detonated in any eight-millisecond period without seismic monitoring, where W = the maximum weight of explosives in pounds; D = the distance, in feet, from the blast site to the nearest protected structure; and Ds = the scaled-distance factor, which may initially be approved by the commission using the values for scaled-distance factor listed in subdivision b. (2) The development of a modified scaled-distance factor may be authorized by the commission on receipt of a written request by the operator, supported by seismographic records of blasting at the minesite. The factor must ensure that the particle velocity will not exceed the prescribed maximum allowable peak particle velocity of subdivision b at a ninety-five percent confidence level. d. The maximum allowable ground vibration will be reduced by the commission beyond the limits otherwise provided by this section if determined necessary to provide damage protection. e. The maximum airblast and ground-vibration standards of this subsection do not apply at structures owned by the permittee and: (1) Not leased to another person. (2) Leased to another person if a written waiver by the lessee is submitted to the commission before blasting. N.D. Admin Code 69-05.2-17-05
Effective August 1, 1980; amended effective June 1, 1983; May 1, 1990; May 1, 1992.General Authority: NDCC 38-14.1-03
Law Implemented: NDCC 38-14.1-24