30 CFR 816.67 - Use of explosives: Control of adverse effects.
(a)General requirements. You must conduct blasting in a manner that prevents -
(1) Injury to persons;
(2) Damage to public or private property outside the permit area;
(3) Adverse impacts on any underground mine; or
(i) Airblast must not exceed the maximum limits listed below at the location of any dwelling, public building, school, church, or community or institutional building outside the permit area, except as provided in paragraph (e) of this section.
|Lower frequency limit of measuring system in Hertz (Hz), plus or minus 3 decibels||Maximum level in decibels (dB)|
|0.1 Hz or lower - flat response 1||134 peak.|
|2 Hz or lower - flat response||133 peak.|
|6 Hz or lower - flat response||129 peak.|
|C-weighted - slow response 1||105 peak dBC.|
1 Only when approved by the regulatory authority.
(ii) If necessary to prevent damage, the regulatory authority must specify lower maximum allowable airblast levels than those of paragraph (b)(1)(i) of this section for use in the vicinity of a specific blasting operation.
(i) You must conduct periodic monitoring to ensure compliance with the airblast standards. The regulatory authority may require airblast measurement of any or all blasts and may specify the locations at which measurements are taken.
(ii) The measuring systems must have an upper-end flat-frequency response of at least 200 Hz.
(c)Flyrock. Flyrock travelling in the air or along the ground must not be cast from the blasting site -
(1) More than one-half the distance to the nearest dwelling or other occupied structure;
(3) Beyond the permit boundary.
(d)Ground vibration. -
(i) In all blasting operations, except as otherwise authorized in paragraph (e) of this section, the maximum ground vibration must not exceed the values approved in the blasting plan required under § 780.15 of this chapter.
(ii) The maximum ground vibration for protected structures listed in paragraph (d)(2)(i) of this section must be established in accordance with either the maximum peak-particle-velocity limits of paragraph (d)(2) of this section, the scaled-distance equation of paragraph (d)(3) of this section, the blasting-level chart of paragraph (d)(4) of this section, or by the regulatory authority under paragraph (d)(5) of this section.
(iii) All structures in the vicinity of the blasting area not listed in paragraph (d)(2)(i) of this section, such as water towers, pipelines and other utilities, tunnels, dams, impoundments, and underground mines, must be protected from damage by establishment of a maximum allowable limit on the ground vibration, submitted by the operator in the blasting plan and approved by the regulatory authority.
(2)Maximum peak particle velocity.
|Distance (D), from the blasting site, in feet||Maximum allowable peak particle velocity for ground vibration, in inches/second 1||Scaled-distance factor to be applied without seismic monitoring (Ds) 2|
|0 to 300||1.25||50|
|301 to 5,000||1.00||55|
|5,001 and beyond||0.75||65|
1 Ground vibration must be measured as the particle velocity. Particle velocity must be recorded in three mutually perpendicular directions. The maximum allowable peak particle velocity applies to each of the three measurements.
2 Applicable to the scaled-distance equation of paragraph (d)(3)(i) of this section.
(ii) You must provide a seismographic record for each blast.
(i) You may use the scaled-distance equation, W=(D/Ds) 2, to determine the allowable charge weight of explosives to be detonated in any 8-millisecond period, without seismic monitoring, where W=the maximum weight of explosives, in pounds; D=the distance, in feet, from the blasting site to the nearest protected structure; and Ds=the scaled-distance factor. The regulatory authority may initially approve the scaled-distance equation using the values for the scaled-distance factor listed in paragraph (d)(2)(i) of this section.
(ii) The regulatory authority may authorize development of a modified scaled-distance factor upon receipt of a written request by the operator, supported by seismographic records of blasting at the minesite. The modified scale-distance factor must be determined such that the particle velocity of the predicted ground vibration will not exceed the prescribed maximum allowable peak particle velocity of paragraph (d)(2)(i) of this section at a 95-percent confidence level.
(i) You may use the ground-vibration limits in Figure 1 to determine the maximum allowable ground vibration.
(ii) If the Figure 1 limits are used, you must provide a seismographic record including both particle velocity and vibration-frequency levels for each blast. The regulatory authority must approve the method for the analysis of the predominant frequency contained in the blasting records before application of this alternative blasting criterion.
(6) The regulatory authority may require that you conduct seismic monitoring of any or all blasts or may specify the location at which the measurements are taken and the degree of detail necessary in the measurement.
(e) The maximum airblast and ground-vibration standards of paragraphs (b) and (d) of this section do not apply at the following locations: