Authority: IC 14-34-2-1

Affected: IC 14-34

Sec. 32. (a) Blasting operations shall be conducted at times approved by the director and announced in the blasting schedule. The permittee shall submit the blasting schedule required by section 31 of this rule to the director for approval sixty (60) days prior to the date of publication specified in section 31(a) of this rule. All blasting shall be conducted between sunrise and sunset, unless nighttime blasting is approved by the director upon showing that the public will be protected from adverse noise and other impacts. The director may limit the area covered by a blasting schedule or specify more restrictive time periods if necessary to protect the public health and safety or welfare.

(b) Unscheduled blasting operations may be conducted only when operator or public health and safety require unscheduled detonation. When the permittee conducts unscheduled blasting operations, the permittee shall do the following:

1. (1) Notify persons within one-half (1/2) mile of the blasting site using audible warning signals.

2. (2) Document the reason for the unscheduled blast, including the following:

   1. (A) Why the blast could not be held over to the next day.
   2. (B) When the blast was actually conducted.
   3. (C) The warning signals given in accordance with section 33(17) of this rule.
3. The director may require any permittee to submit a report of unscheduled blasts if needed to respond to citizen complaints concerning blasting.
4. (3) Where the unscheduled blast is an unapproved nighttime blast, take sufficient measures to ensure the public will be protected from adverse noise and other impacts.

(c) Warning and all-clear signals of different character or pattern that are audible within a range of one-half (1/2) mile from the point of the blast shall be given. Each person within the permit area and each person who resides or regularly works within one-half (1/2) mile of the permit area shall be communicated this information through the public notice of the blasting schedule.

(d) Access to an area possibly subject to flyrock from blasting shall be regulated to protect the public and livestock. Access to the blasting area shall be controlled to prevent the presence of livestock or unauthorized personnel during blasting and until an authorized representative of the permittee has reasonably determined that:

1. (1) no unusual circumstances, such as imminent slides or undetonated charges, exist; and
2. (2) access to and travel in or through the area can be safely resumed.

(e) Airblast requirements are as follows:

1. (1) Airblast shall be controlled so that it does not exceed the maximum limits specified below at any dwelling, public building, school, church, or community or institutional building unless such building is owned by the permittee and is not leased to any other person. If a building owned by the permittee is leased to another person, the lessee may sign a waiver relieving the permittee from meeting the airblast limitations of this subdivision. The written waiver shall be submitted to the director before blasting commences.

   Lower frequency limits of measuring system, Hz (± 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.

2. (2) All measuring systems used shall have a flat frequency response of at least two hundred (200) hertz at the upper end.
3. (3) The permittee may satisfy the provisions of this section by meeting any of the four (4) specifications in the chart in subdivision (1) provided, however, the one-tenth (0.1) hertz or lower-flat response or C-weighted slow response can only be used if approved by the director.
4. (4) The director may require airblast measurements of any or all blasts and may specify the location of such measurements. If necessary to prevent damage, the director shall specify lower maximum allowable airblast levels than those of subdivision (1) for use in the vicinity of a specific blasting operation.
5. (5) The permittee shall conduct periodic monitoring to ensure compliance with the airblast standards of subdivision (1).

(f) Flyrock, including material traveling along the ground, shall not be cast from the blasting site more than one-half (1/2) the distance to the nearest dwelling or other occupied structure, beyond the boundary of the bonded area, or beyond the area of regulated access required under subsection (d).

(g) Blasting shall be conducted to prevent injury to persons, damage to public or private property, adverse impacts on any underground mine, and change in the course, channel, or availability of ground or surface waters outside the permit area.

(h) Requirements for maximum ground vibrations are as follows:

1. (1) In all blasting operations, except as otherwise authorized in this section, the maximum ground vibration shall not exceed the limits approved in the blasting plan required by 312 IAC 25-4-42. The maximum ground vibration at the location of any dwelling, public building, school, church, or community or institutional building shall be established in accordance with either:

   1. (A) the maximum peak particle-velocity limits of subdivision (2);
   2. (B) the scaled-distance equation of subdivision (3);
   3. (C) the blasting-level chart of subdivision (4); or
   4. (D) by the director under subdivision (5).
2. All structures in the vicinity of the blasting area, not listed in this subdivision, including, but not limited to, water towers, pipelines, and other utilities, tunnels, dams, impoundments, and underground mines, shall be protected from damage by establishment of a maximum allowable limit on the ground vibration, submitted by the permittee in the blasting plan and approved by the director. Provided, however, abandoned underground workings that are within the permit boundary and are to be mined through according to approved mining plans are not subject to a ground vibration limitation.

3. (2) Maximum peak particle velocity requirements as follows:

   1. (A) The maximum ground vibration, measured as peak particle velocity, shall not exceed the following limits at the location of any dwelling, public building, school, church, or community or institutional building:

      Distance (D) from the blasting site (feet)	Maximum allowable peak particlevelocity (Vmax) for ground vibration (inch/second)	Scaled-distancefactor (Ds) to be applied without seismic monitoring1
      0 to 300	1.25	50
      301 to 5,000	1.00	55
      5,001 and beyond	0.75	65
      1Applicable to the scaled distance equation of subdivision (3)(A).

   2. (B) A seismographic record shall be obtained for each blast. The results of the record shall be made a part of the blasting record required by section 33 of this rule. Particle velocity shall be measured in three (3) mutually perpendicular directions. The maximum allowable peak particle velocity shall apply to each of the three (3) measurements.

4. (3) Scaled-distance equation as follows:

   1. (A) A permittee may use the scaled-distance equation: W = (D/Ds)²

   2. to determine the allowable charge-weight of explosives to be detonated in any 8-millisecond period, without seismic monitoring.

      Where:	W	=	Maximum weight of explosives, in pounds, that can be detonated in any 8-millisecond period.
      	D	=	Distance, in feet, from the blasting site to the nearest protected structure.
      	Ds	=	Scaled-distance factor.

   3. that may initially be approved by the director using the values for scaled-distance factor listed in subdivision (2)(A).
   4. (B) The development of a modified scaled-distance factor may be authorized by the director on receipt of a written request by the permittee, supported by seismographic records of blasting at the mine site. The modified scaled-distance factor shall be determined such that the particle velocity of the predicted ground vibration will not exceed the prescribed maximum allowable peak particle velocity of subdivision (2)(A) at a ninety-five percent (95%) confidence level.
5. (4) A permittee may use the ground vibration limits found in the following chart to determine the maximum allowable ground vibration:
6. If the chart limits are used, a seismographic record including both particle-velocity and vibration-frequency levels shall be obtained for each blast. The method for the analysis of the predominant frequency contained in the blasting records shall be approved by the director before application of this alternative blasting criterion.
7. (5) The maximum allowable ground vibration shall be reduced by the director beyond the limits otherwise provided by this section, if determined necessary to provide damage protection.
8. (6) The director may require a permittee to conduct seismic monitoring of any or all blasts and may specify the location at which the measurements are taken and the degree of detail necessary in the measurement.

(i) The maximum airblast and ground vibration limitations of subsections (e) and (h) shall not apply at the following locations:

1. (1) At structures owned by the permittee and not leased to another party.
2. (2) At structures owned by the permittee, and leased to another party if a written waiver by the lessee is submitted to the director prior to blasting.

(Natural Resources Commission; 312 IAC 25-6-32; filed Jun 21, 2001, 2:53 p.m.: 24 IR 3524, eff Dec 1, 2001; errata filed Aug 17, 2001, 1:50 p.m.: 25 IR 106; readopted filed May 29, 2007, 9:51 a.m.: 20070613-IR-312070146RFA; readopted filed Sep 19, 2013, 10:12 a.m.: 20131016-IR-312130125RFA; readopted filed Mar 26, 2019, 3:40 p.m.: 20190424-IR-312190011RFA; readopted filed Mar 25, 2025, 9:50 a.m.: 20250423-IR-312240574RFA)