Current through Register Vol. 6, March 22, 2024
(1) If the department determines that the
preponderance of evidence indicates that property damage or safety hazards are
or were caused by blasting associated with exploration or mining activities by
an operator, the department shall issue an order. In the event the order is not
complied with, the department shall issue an order imposing requirements
reasonably necessary to prevent property damage or safety hazards.
(2) The department may require as many of the
following requirements as are reasonably necessary for this purpose:
(a) Each operator shall comply with all
applicable state and federal laws in the use of explosives.
(b) All blasting operations must be conducted
by experienced, trained, and competent persons who understand the hazards
involved.
(c) A record of each
blast occurring over a period to be determined by the department, including
seismograph records, must be prepared and retained for at least three years and
must be available for inspection by the department on request. Blasting records
must be accurate and completed in a timely fashion. The records must contain
the following data:
(i) name of the operator
conducting the blast;
(ii)
location, date, and time of the blast;
(iii) name, signature, and, if applicable,
license number and appropriate certification program name of
blaster-in-charge;
(iv) direction
and distance, in feet, to the nearest inhabited building or structure either:
(A) not located in the permit area;
or
(B) not owned nor leased by the
person who conducts the mining activities;
(v) weather conditions, including
temperature, wind direction and approximate wind velocity;
(vi) type of material blasted;
(vii) number of holes, burden, and
spacing;
(viii) diameter and depth
of holes;
(ix) types of explosives
used;
(x) total weight of
explosives used;
(xi) maximum
weight of explosives detonated within any eight-millisecond period;
(xii) maximum number of holes detonated
within any eight-millisecond period;
(xiii) initiation system;
(xiv) type and length of stemming;
(xv) mats or other protections
used;
(xvi) type of delay detonator
and delay periods used;
(xvii)
sketch of the delay pattern;
(xviii) number of persons in the blasting
crew;
(xix) seismographic and
airblast records, where required, including:
(A) the calibration signal of the gain
setting or certification of annual calibration;
(B) seismographic reading, including exact
location of seismograph and its distance from the blast, airblast reading,
dates and times of readings;
(C)
name of the person taking the seismograph reading; and
(D) name of the person and firm analyzing the
seismographic record.
(d) When blasting is conducted in an area
where access is not restricted, warning and all-clear signals of different
character that are audible at all points within a range of 1/2 mile from the
point of the blast must be given. Each person within the permit area and each
person who resides or regularly works within 1/2 mile of the permit area must
be notified of the meaning of the signals through appropriate instructions.
These instructions must be periodically delivered or otherwise communicated in
a manner that can be reasonably expected to inform such persons of the meaning
of the signals.
(e) Blasting must
not eject flyrock off property controlled by the operator. Access to the
blasting area and to areas where blasting effects, such as flyrock, occur, must
be controlled by methods such as signs and fencing to prevent the presence of
livestock or unauthorized personnel during blasting and until an authorized
representative of the operator has reasonably determined:
(i) that no unusual circumstances, such as
imminent slides or undetonated charges, exist; and
(ii) that access to and travel in or through
the area can be safely resumed.
(f)
(i)
Airblast must be controlled so that it does not exceed the values specified
below at any dwelling, public building, school, church, or commercial, public,
or institutional structure, unless the structure is owned by the operator and
is not leased to any other person. If a building owned by the operator is
leased to another person, the lessee may sign a waiver relieving the operator
from meeting the airblast limitations of this section.
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Lower Frequency limit of Maximum level in
measuring system, Hertz (Hz) (+3dB)
decibels (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.
If necessary to prevent damage based upon the consultant's
report, the department shall specify lower maximum allowable airblast levels
than those above.
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(ii) In all cases, except the
C-weighted, slow-response system, the measuring systems used must have a flat
frequency response of at least 200 Hz at the upper end. The C-weighted system
must be measured with a Type 1 sound level meter that meets the standard
American National Standards Institute (ANSI) S 1.4-1971 specifications. These
specifications are hereby incorporated by reference. Copies of this publication
are on file with the Department of Environmental Quality, P.O. Box 200901,
Helena, MT 59620-0901.
(iii) The
operator may satisfy the provisions of this subsection by meeting any of the
four specifications in the chart in (i).
(iv) The operator shall conduct periodic
monitoring to ensure compliance with the airblast standards. The department may
require an airblast measurement of any or all blasts, and may specify the
location of such measurements, except as noted in (i).
(g) Whenever the standards contained in (k)
(i) and (o) (iii) have been exceeded, or whenever, based upon the consultant's
report, it has been determined to be necessary to protect public safety or
property, the department may require modification of blasting activities to
protect:
(i) public, private or institution
building, including any dwelling, school, church, hospital, or nursing
facility; and
(ii) facilities
including, but not limited to, disposal wells, petroleum or gas storage
facilities, municipal water storage facilities, fluid transmission pipelines,
gas or oil collection lines, or water and sewage lines or any active or
abandoned underground mine.
(h) A blast design, including measures to
protect the facilities in (g) must be submitted to the department prior to
continued blasting.
(i) Flyrock,
including blasted material traveling along the ground, must not be cast from
the blasting vicinity more than half the distance to the nearest dwelling or
other occupied structure and in no case beyond the line of property owned or
leased by the permittee, or beyond the area of regulated access required under
(e).
(j) Blasting must 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.
(k)
(i) In all blasting operations, except as
otherwise authorized in this subsection, the maximum peak particle velocity
must not exceed the following limits at the location of any dwelling, public
building, school, church, or commercial, public, or institutional structure:
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Distance (D) Maximum allowable Scaled-distance
from the peak particle velocity factor to be applied
blasting site, (V max) for ground without seismic
in feet vibration, in inches/ monitoring (Ds)
second
___________________________________________________________________
0 to 300 1.25 50
301 to 5,000 1.00 55
5,001 and beyond 0.75 65
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(ii) Peak particle velocities must
be recorded in three mutually perpendicular directions. The maximum peak
particle velocity is the largest of any of the three measurements.
(iii) The department shall reduce the maximum
peak velocity allowed if a lower standard is required, based upon the
consultant's report, to prevent damage or to protect public safety because of
density of population or land use, age or type of structure, geology or
hydrology of the area, frequency of blasts, or other factors.
(l) If blasting is conducted in
such a manner as to avoid adverse impacts on any underground mine and changes
in the course, channel, or availability of ground or surface water outside the
permit area, then the maximum peak particle velocity limitation of (k) does not
apply at the following locations:
(i) at
structures owned by the operator and not leased to another party; and
(ii) at structures owned by the operator and
leased to another party, if a written waiver by the lessee is submitted to the
department prior to blasting.
(m) An equation for determining the maximum
weight of explosives that can be detonated within any eight-millisecond period
is in (n). If the blasting is conducted in accordance with this equation, the
peak particle velocity is deemed to be within the limits specified in
(k).
(n) The maximum weight of
explosives to be detonated within any eight-millisecond period may be
determined by the formula
W=(D/Ds)
2 where W=the maximum weight of
explosives, in pounds, that can be detonated in any eight-millisecond period;
D=the distance, in feet, from the blast to the nearest public building or
structure, dwelling, school, church, or commercial or institutional building or
structure, except as noted in (l) ; and Ds=the scaled distance factor, using
the values identified in (k).
(o)
(i)
Whenever a seismograph is used to monitor the velocity of ground motion and the
peak particle velocity limits of (k) are not exceeded, the equation in (n) need
not be used. If that equation is not used by the operator, a seismograph record
must be obtained for each shot.
(ii) The use of a modified equation to
determine maximum weight of explosives per delay for blasting operations at a
particular site may be approved by the department, on receipt of a petition
accompanied by reports including seismograph records of test blasting on the
site. The department may not approve the use of a modified equation if the peak
particle velocity for the limits specified in (k) are exceeded, meeting a 95%
statistical confidence level.
(iii)
The operator may use the ground vibration limits in Figure 1 (
30 CFR
816.67 (d) (4)) as an alternative to (i) and
(ii), upon approval by the department.
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(iv) The
department may require a seismograph record of any or all blasts and may
specify the location at which the measurements are to be taken.