(a) General requirements.
  (1) Blasting shall be conducted in a manner that will 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.
  (2) Except where lesser distances are approved by the Commission, based upon a pre-blasting survey, seismic investigation, and an approved blast design submitted in accordance with the requirements of §12.357(d) of this title (relating to Use of Explosives: General Requirements), blasting shall not be conducted within:
    (A) 1,000 feet of any building used as a dwelling, public building, school, church, hospital, nursing facility, or community or institutional building outside the permit area; and
    (B) 500 feet of facilities including, but not limited to, disposal wells, petroleum or gas storage facilities, active and abandoned underground mines, fluid-transmission pipelines, gas or oil-collection lines, or water and sewage lines.
(b) Scheduled blasting. All blasting shall be conducted between sunrise and sunset, unless otherwise approved by the Commission upon a showing by the operator that the public will be protected from adverse noise and other impacts.
  (1) The Commission may limit the area covered, timing and sequence of blasting as listed in the blasting schedule if such limitations are reasonable and necessary in order to protect the public health, safety or welfare.
  (2) Blasting may be conducted between sunset and sunrise if:
    (A) a blast that has been prepared during the afternoon must be delayed due to the occurrence of an unavoidable hazardous condition and cannot be delayed until the next day because a potential safety hazard could result that cannot be adequately mitigated;
    (B) in addition to the required warning signals, oral notices are provided to persons within 1/2 mile of the blasting site; and
    (C) a complete written report of blasting at night is filed by the operator with the Commission not later than three days after the night blasting. The report shall include a description in detail of the reasons for the delay in blasting including why the blast could not be held over to the next day, when the blast was actually conducted, the warning notices given, and a copy of the blast report required by §12.362 of this title (relating to Use of Explosives: Records of Blasting Operations).
(c) Unscheduled blasting. Unscheduled blasting may be conducted only where public or operator health and safety so require, and for emergency blasting actions. The operator shall use audible signals to notify residents within 1/2 mile of the blasting site prior to conducting unscheduled blasting, and shall document the reason for the unscheduled blasting in accordance with §12.362 of this title (relating to Use of Explosives: Records of Blasting Operations).
(d) Warnings. All blasting shall require blasting signs, warnings, and access control.
  (1) Blasting signs shall meet the specifications of §12.330 of this title (relating to Signs and Markers). The operator shall:
    (A) conspicuously place signs reading, "Blasting Area", along the edge of any blasting area that comes within 100 feet of any public road right-of-way, and at the point where any other road provides access to the blasting area; and
    (B) conspicuously place at all entrances to the permit area from public roads or highways, signs reading, "Warning! Explosives in Use". The signs shall clearly list and describe the meaning of the audible blast warning and all-clear signals that are in use, and shall explain the marking of the blasting areas and charged holes awaiting firing within the permit area.
  (2) Warning and all-clear signals of different character or pattern that are audible within a range of 1/2 mile from the blasting site shall be given. The operator shall notify each person within the permit area and each person who resides or regularly works within 1/2 mile of the permit area regarding the meaning of the signals in the blasting schedule.
(e) Access control. Access to the blasting area shall be controlled to prevent the presence of livestock or unauthorized persons during blasting and until an authorized representative of the operator has reasonably determined that:
  (1) no unusual hazards, such as imminent slides or undetonated charges, exist; and
  (2) access to and travel within the blasting area can be safely resumed.
(f) Airblast.
  (1) Limits.
    (A) Airblast shall not exceed the maximum limits specified below at the location of any dwelling, public building, school, church, or community or institutional building outside the permit area, except as provided in subsection (i) of this section.
Attached Graphic
    (B) In all cases except the C-weighted, slow-response, the measuring systems used shall have a flat frequency response of at least 200 Hz at the upper end. The C-weighted shall be measured with a Type 1 sound-level meter that meets the standard American National Standards Institute (ANSI) S1.4-1971 specifications. ANSI S1.4-1971 is on file and available for inspection at the offices of the Commission, 170l N. Congress Avenue, Austin, Texas.
    (C) If necessary to prevent damage, the Commission shall specify lower maximum allowable airblast levels than those of subparagraph (A) of this paragraph for use in the vicinity of a specific blasting operation.
  (2) Monitoring.
    (A) The operator shall conduct periodic monitoring to ensure compliance with the airblast standards. The Commission may require airblast measurement of any or all blasts, and may specify the locations at which the measurements are to be taken.
    (B) The measuring systems shall have an upper-end flat frequency response of at least 200 Hz.
(g) Flyrock. Flyrock traveling in the air or along the ground shall not be cast from the blasting site:
  (1) more than one half the distance to the nearest dwelling or other occupied structure;
  (2) beyond the area of control required under subsection (e) of this section; or
  (3) beyond the permit boundary.
(h) Ground vibration.
  (1) General. In all blasting operations, except as otherwise authorized in subsection (i) of this section, the maximum ground vibration shall not exceed the values approved in the blasting plan required under §12.141 of this title (relating to Operation Plan: Blasting). The maximum ground vibration for protected structures listed in paragraph (2)(A) of this subsection shall be established in accordance with the maximum peak-particle-velocity limits of paragraph (2) of this subsection, the scaled-distance equation of paragraph (3) of this subsection, the blasting-level chart of paragraph (4) of this subsection, or by the Commission under paragraph (5) of this subsection. All structures in the vicinity of the blasting area, not listed in paragraph (2)(A) of this subsection, such as 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 operator in the blasting plan and approved by the Commission.
  (2) Maximum peak particle velocity.
    (A) The maximum ground vibration shall not exceed the following limits at the location of any dwelling, public building, school, church, or community or institutional building outside the permit area:
Attached Graphic
    (B) A seismographic record shall be provided for each blast.
  (3) Scaled-distance equation.
    (A) 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 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, which may initially be approved by the Commission using the values for the scaled-distance factor listed in paragraph (2)(A) of this subsection.
    (B) 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 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 paragraph (2)(A) of this subsection, at a 95% confidence level.
  (4) Blasting-level chart.
Cont'd...