Virginia Administrative Code
Title 4 - CONSERVATION AND NATURAL RESOURCES
Agency 25 - DEPARTMENT OF ENERGY
Chapter 130 - COAL SURFACE MINING RECLAMATION REGULATIONS
Part 816 - Permanent Program Performance Standards-Surface Mining Activities
Section 4VAC25-130-816.67 - Use of explosives; control of adverse effects
Universal Citation: 4 VA Admin Code 25-130-816-67
Current through Register Vol. 41, No. 3, September 23, 2024
(a) General requirements. 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 surface or ground water outside the permit area.
(b) Airblast.
(1) Limits.
(i) Airblast shall 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 Hz (±3 dB) | Maximum level, in dB |
| 0.1 Hz or lower - flat response1 | 134 peak |
| 2 Hz or lower - flat response | 133 peak |
| 6 Hz or lower - flat response | 129 peak |
| C-weighted-slow response1 | 105 peak dBC |
| 1Only when approved by the division | |
(ii) If necessary to prevent damage, the
division shall 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.
(2)
Monitoring.
(i) The permittee shall conduct
periodic monitoring to ensure compliance with the airblast standards. The
division may require airblast measurement of any or all blasts and may specify
the locations at which such measurements are taken.
(ii) The measuring systems shall have an
upper-end flat-frequency response of at least 200 Hz.
(c) Flyrock. Flyrock travelling 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
4VAC25-130-816.66(c); or
(3) Beyond
the permit boundary.
(d) Ground vibration.
(1) General. In all blasting
operations, except as otherwise authorized in Paragraph (e) of this section,
the maximum ground vibration shall not exceed the values approved in the
blasting plan required under 4VAC25-130-780.13. The maximum ground vibration
for protected structures listed in Paragraph (d)(2)(i) of this section shall be
established in accordance with either the maximum peak-particle-velocity limits
of Paragraph (d)(2), the scaled distance equation of Paragraph (d)(3), the
blasting-level chart of Paragraph (d)(4), or by the division under Paragraph
(d)(5) of this section. 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, 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 division.
(2)
Maximum peak particle velocity.
(i) 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:
| 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 (Ds) |
| 0 to 300 | 1.25 | 50 |
| 301 to 5,000 | 1.00 | 55 |
| 5,001 and beyond | 0.75 | 65 |
| 1Ground 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. | ||
| 2Applicable to the scaled-distance equation of Paragraph (d)(3)(i) of this section | ||
(ii) A seismographic record shall be provided
for each blast.
(3)
Scale-distance equation.
(i) The permittee
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 division using the values for scaled-distance factor listed in
Paragraph (d)(2)(i) of this section.
(ii) The development of a modified
scaled-distance factor may be authorized by the division on receipt of a
written request by the permittee, supported by seismographic records of
blasting at the minesite. 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 (d)(2)(i) of this section, at a 95-percent confidence
level.
(4)
Blasting-level chart.
(i) The permittee may
use the ground-vibration limits in Figure 1 to determine the maximum allowable
ground vibration.
(ii) If the
Figure 1 limits are used, a seismographic 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 division before application of this
alternative blasting criterion.
(5) The maximum allowable ground vibration
shall be reduced by the division below the limits otherwise provided by this
section, if determined necessary to provide damage protection.
(6) The division may require the permittee 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
measurement.
(e) The maximum airblast and ground-vibration standards of Paragraphs (b) and (d) of this section shall not apply at the following locations:
(1) At structures owned by the permittee and
not leased to another person.
(2)
At structures owned by the permittee and leased to another person, if a written
waiver by the lessee is submitted to the division before blasting.
Statutory Authority
§§ 45.1-161.3 and 45.1-230 of the Code of Virginia.
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