Current through Register Vol. 35, No. 18, September 24, 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. Airblasts.
(1) Limits.
(a) 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 Subsection E of 19.8.20.2032 NMAC.
Lower frequency limit Maximum Level,
of measuring system, in Hz (± 3 dB) 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
director.
(b) If necessary
to prevent damage, the director shall specify lower maximum allowable airblast
levels than those of Subparagraph (a) of Paragraph (1) of Subsection B of
19.8.20.2032 NMAC 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
director may require airblast measurement of any or all blasts and may specify
the locations at which such measurements are taken.
(b) 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
Subsection C of 19.8.20.2031 NMAC; or
(3) beyond the permit boundary.
D. Ground vibration.
(1) General. In all blasting operations,
except as otherwise authorized in Subsection E of 19.8.20.2032 NMAC, the
maximum ground vibration shall not exceed the values approved in the blasting
plan required under 19.8.9.902 NMAC. The maximum ground vibration for protected
structures listed in Subparagraph (a) of Paragraph (2) of Subsection D of
19.8.20.2032 NMAC shall be established in accordance with either the maximum
peak-particle-velocity limits of Paragraph (2) of Subsection D of 19.8.20.2032
NMAC, the scaled-distance equation of Paragraph (3) of Subsection D of
19.8.20.2032 NMAC, the blasting-level chart of Paragraph (4) of Subsection D of
19.8.20.2032 NMAC, or by the director under Paragraph (5) of Subsection D of
19.8.20.2032 NMAC. All structures in the vicinity of the blasting area, not
listed in Subparagraph (a) of Paragraph (2) of Subsection D of 19.8.20.2032
NMAC, 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 director.
(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:
Distance (D) from the Maximum allowable
Scaled-distance
blasting site, in feet peak particle velocity factor to
be applied
factor (V max) for without seismic
ground vibration,
monitoring2 (Ds)
in
inches/second1
0 to 300 1.25 50
301 to 5,000 1.00 55
5,000 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 Subparagraph (a) of Paragraph (3) of Subsection D of 19.8.20.2032
NMAC.
(b) A seismographic
record shall be provided for each blast.
(3) Scaled-distance equation. 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 director using the values for scaled-distance
factor listed in Subparagraph (a) of Paragraph (2) of Subsection D of
19.8.20.2032 NMAC.
(a) The development of a
modified scaled-distance factor may be authorized by the director on receipt of
a written request by the operator, 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
Subparagraph (a) of Paragraph (2) of Subsection D of 19.8.20.2032 NMAC, at a
95-percent confidence level.
(4) Blasting-level chart.
(a) An operator may use the ground-vibration
limits in Figure 1 to determine the maximum allowance ground vibration.
Click
to View Image
(b) 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 director before application of this alternative blasting
criterion.
(5) The
maximum allowable ground vibration shall be reduced by the director beyond the
limits otherwise provided by 19.8.20 NMAC, if determined necessary to provide
damage protection.
(6) The
director 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 measurement.
E. The maximum airblast and ground-vibration
standards of Subsections B and D of 19.8.20.2032 NMAC 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
director before blasting.
