020-6 Wyo. Code R. § 6-4 - Blasting Standards

(a) General.

(i) Blasting shall 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.

(ii) All blasting shall be conducted during time approved by the Administrator and announced on the blasting schedule. Based on public requests or other considerations, including the proximity to residential areas, the Administrator may limit the area covered, timing and sequence of blasting. Blasting shall be conducted between sunrise and sunset unless night-time blasting is approved by the Administrator based on public protection and annoyance considerations.

(iii) Blasting may not be conducted at times different from those announced in the blasting schedule except in conditions where operator or public safety requires unscheduled detonation or for emergency blasting actions. Reasons for unscheduled detonation shall be documented.

(iv) Warning and all-clear signals of different character that are audible within a range of one-half mile from the point of the blast shall be given. All persons within the area covered under the term of permit and those who reside or regularly work within one-half mile of this same area shall be notified of the meanings of the signals in the blasting schedule.

(v) Area of control. Access to the blasting area shall be controlled to protect the public and livestock from the effects of blasting and to prevent unauthorized entry. Access control shall continue until the permittee's authorized representative has determined that no unusual circumstances such as imminent slides or undetonated charges exist and access to and travel in or through the area can safely resume.

(vi) Areas in which charged (loaded) holes are awaiting firing shall be guarded against unauthorized entry.

(b) Limitations.

(i) Airblast shall not exceed the values specified below at any dwelling, public building, school, church, and community or institutional building outside the permit area, unless the building is owned by the operator and not leased to another, or, if leased, the lessee signs a waiver relieving the operator from meeting the limitations. If necessary to prevent damage, the Administrator shall specify lower maximum allowable airblast levels.

Lower frequency limit of measuring system, Hz (+3dB) 0.1 Hz or lower-flat response 1 2 Hz or lower-flat response	Maximum level in dB
	134 peak
	133 peak
C-weighted, slow response 1	129 peak
6 Hz or lower-flat response	105 peak dBC

¹ Only if approved by the Administrator.

(A) The operator shall conduct periodic monitoring to ensure compliance with the airblast standards. The Administrator shall request monitoring in certain instances, including but not limited to complaints, blasting in sensitive areas, and in areas where there is reason to believe airblast limits may be exceeded. The measuring systems shall have an upper-end flat frequency response of at least 200 Hz.

(ii) Flyrock shall not be cast from the blasting site more than half the distance to the nearest occupied structure or beyond either the permit boundary or the area of control required under (a)(v) above.

(iii) In all blasting operations except as specified below, the maximum ground vibration shall not exceed the values approved in the blasting plan. The maximum ground vibration at the location of any dwelling, public building, school, church, and community or institutional building outside the permit area shall not exceed the values established by paragraph (iv), the scaled-distance equation of paragraph (v), the blasting level chart of paragraph (vi), or by the Administrator under paragraph (vii). All other structures such as water towers, pipelines, tunnels, dams, impoundments, and underground mines, shall be protected from damage by establishment of a maximum allowable limit on ground vibration, submitted by the operator in the blasting plan and approved by the Administrator. The ground vibration standards do not apply at structures owned by the operator and not leased to another, or, if leased, the lessee signs a waiver relieving the operator from meeting the limitations.

Distance (D) from the Blasting Site in feet	Maximum allowable peak particle velocity (Vmax) for ground vibration in inches/second1	Scaled distance factor to be applied without seismic monitoring2
0 to 300	1.25	50
301 to 5000	1.00	55
5001 and beyond	0.75	65

¹ Ground vibration shall be measured as the particle velocity. Particle velocity shall be recorded in three mutually perpendicular directions. The maximum allowable peak particle velocity shall apply to each of the three measurements.

² Applicable to the scaled-distance equation of Paragraph (v).

(iv) Maximum peak particle velocity applicable when seismograph records are provided for each blast:

(v) 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 blasting site to the nearest protected structure; and Ds = the scaled-distance factor, which may initially be approved by the Administrator using the values for scaled-distance factor listed in paragraph (iv) above.

(A) Upon written request by the operator with seismographic records, the Administrator may authorize a modified scaled-distance factor. The modified scaled-distance factor shall be determined such that particle velocity of the predicted ground vibration will not exceed the prescribed maximum allowable peak particle velocity of paragraph (iv) above, at a 95 percent confidence level.

(vi) An operator may use the ground vibration limits in Figure 1 (blasting-level chart) to determine the maximum allowable ground vibration. A seismograph record including both particle velocity and vibration frequency levels shall be provided for each blast. The method for the analysis of the predominant frequency contained in the blasting records shall be approved by the Administrator before application of this alternative blasting criterion.

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(vii) The maximum allowable ground vibration shall be reduced by the Administrator beyond the limits otherwise provided by paragraphs (iv)-(vi), if necessary to provide damage protection. The Administrator may require an operator to 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 measurements.

(c) Blast Design. Permit requirements pertaining to blasting are located in Chapter 2, Section 2(b)(v).

(i) Anticipated blast design(s) shall be submitted if blasting operations will be conducted within:

(A) 1,000 feet of any building used as a dwelling, public building, school, church, or community or institutional building outside the permit area; or

(B) 500 feet of an active or abandoned underground mine.

(ii) The blast design may be presented as part of a permit application or at a time, before the blast, approved by the Administrator.

(iii) The blast design shall contain sketches of the drill patterns, delay periods, and decking and shall indicate the type and amount of explosives to be used, critical dimensions, and the location and general description of structures to be protected, as well as a discussion of design factors to be used, which protect the public and meet the applicable airblast, flyrock, and ground-vibration standards in (b) above.

(iv) The blast design shall be prepared and signed by a certified blaster.

(v) The Administrator may require changes to the design submitted.

Notes

020-6 Wyo. Code R. § 6-4