(a) Blasting shall be conducted between
sunrise and sunset, at times announced in the blasting schedule, except that
mine opening blasting conducted after the second blast, for that mine opening,
may be conducted at any time of day or night as necessary to maintain stability
of the mine opening to protect the health and safety of mineworkers. For mine
opening blasting conducted after the second blast, for that mine opening, the
Department may approve ground vibration and airblast limits at a dwelling,
public building, school, church or commercial or institutional structure, that
are less stringent than those specified in subsection (e) or (m) if consented
to, in writing, by the structure owner and lessee, if leased to another party.
(b) The Department may specify
more restrictive time periods, airblast or ground vibration limits, based on
public requests or other relevant information, according to the need to
adequately protect the public from the adverse affects of ground vibration,
airblast or safety hazards.
(c)
Warning and all-clear signals shall be different in pattern, audible with a
range of 1/2 mile from the point of the blast, sounded before and after each
blast. Persons who work within the 1/2 mile of the blasting area shall be
notified of the meaning of the signals through appropriate instructions. These
instructions shall be periodically delivered or otherwise communicated in a
manner which can be reasonably expected to inform these persons of the meaning
of the signals. A person who conducts blasting incident to surface mining
activities shall:
(1) When a blast is about to
be fired, give sufficient warning that persons approaching the blast area may
be warned of the danger and be given ample time to retreat a safe distance from
the blast area.
(2) When electric
blasting operations are located near highways or other public ways, erect signs
at least 500 feet from the blast area reading: BLAST AREA-SHUT OFF ALL TWO-WAY
RADIOS. The letters of these signs shall be at least 4 inches in height on a
contrasting background.
(3) Place
at the entrances to the permit area from public roads or highways conspicuous
signs which state "Warning. Explosives in Use" which clearly explain the blast
warning and all clear signals that are in use and which explain the marking of
blasting areas and charged holes within the permit area.
(d) Access to an area possibly subject to
flyrock from blasting shall be controlled to protect the public and livestock.
Access to the area shall be controlled to prevent the presence of livestock or
unauthorized personnel during blasting and until an authorized representative
of the person who conducts the surface mining activities has reasonably
determined:
(1) That no unusual circumstances,
such as imminent slides or undetonated charges, exist.
(2) That access to and travel in or through
the area can be safely resumed.
(e) Airblast shall be controlled so that it
does not exceed the level specified in this subsection at a dwelling, public
building, school, church or commercial or institutional structure, unless the
structure is located on the permit area when the structure owner and lessee, if
leased to another party, have each signed a waiver relieving the operator from
meeting the airblast limitations of this subsection.
(1) The maximum allowable airblast level is
133 dBL.
(2) If necessary to
prevent damage, the Department will specify lower maximum allowable airblast
levels than those of this subsection for use in the vicinity of a specific
blasting operation. The measuring systems used shall have a flat response of at
least 200 Hz at the upper end. The Type 1 sound level meter shall use the slow
response C- weighted network and shall meet American National Standards
Institute (ANSI) S1.4-1971 specifications. The ANSI S1.4-1971 is incorporated
by reference.
(3) The operator
shall conduct periodic monitoring to ensure compliance with the airblast
standards. The Department may require an airblast measurement of blasts, and
may specify the location of the measurements.
(f) Requirements for blasting are as follows:
(1) Public highways and entrances to the
operation shall be barricaded and guarded by the operator if the highways and
entrances to the operations are located within 800 feet of a point where a
blast is about to be fired. The operator may use an alternative measure to this
requirement if the operator demonstrates, to the Department's satisfaction,
that the alternative measure is at least as effective at protecting persons and
property from the adverse affects of a blast. Alternative measures are measures
such as:
(i) Slowing or stopping traffic in
coordination with appropriate State or local authorities, including local
police.
(ii) Using mats to suppress
fly rock.
(iii) Designing the blast
to prevent damage or injury to persons and property located on the public
highways or at the operation's entrances by using design elements such as:
(A) Orienting the blast so that the direction
of relief is away from public highways or operation entrances.
(B) Adjusting blast design parameters
including:
(I) The diameter of
holes.
(II) The number of
rows.
(III) The number of
holes.
(IV) The amount and type of
explosive.
(V) The burden and
spacing.
(VI) The amount and type
of stemming.
(VII) The powder
factor.
(2) When a blast is about to be fired within
200 feet of a pipeline, the operator shall exercise necessary caution as needed
for the protection of the pipeline. The operator shall notify the owner of the
line of the operator's intention to blast, giving a description of the
precautionary measures that will be taken.
(3) When blasting is to be done within 1,000
feet of schools or public buildings, it shall be done only during the time
approved by the Department. Prior to the blasts, the operator or foreman in
charge of the blasting operation shall, within 24 hours prior to the blast,
notify persons within this area that a blast is to be detonated. Approval of
the method of notification shall be obtained from the Department prior to
commencing blasting.
(4) Blasting
may not be done within the confines of an area of 300 feet of an occupied
dwelling unless prior written consent of the property owner has been
obtained.
(5) Flyrock, including
blasted material traveling along the ground, may not be cast from the blasting
vicinity more than one-half the distance to the nearest dwelling or other
occupied structure and in no case beyond the permit boundary, or beyond the
area or regulated access required under subsection (d).
(6) Notwithstanding other provisions in this
part, no blasting, whether of overburden or of coal, may be done or performed
in a manner and under circumstances or conditions to eject debris into the air,
to constitute a hazard or danger or do harm or damage to persons or property in
the area of the blasting.
(g) Blasting shall be conducted to prevent
injury to persons, damage to public or private property outside the permit
area, adverse impacts on an underground-mine, or availability of groundwaters
or surface waters; and shall be prohibited in cases when the effect of the
blasting is liable to change the course or channel of a stream.
(h) In blasting operations, except as
otherwise authorized in this section, the maximum peak particle velocity may
not exceed the values approved in the blast plan required by §
87.64 (relating to blasting plan)
at the location of a dwelling, public building, school, church, commercial or
institutional building or other structure. Peak particle velocities shall be
recorded in three mutually perpendicular directions. The maximum peak particle
velocity shall be the largest of any of three measurements. The Department may
reduce the maximum peak particle velocity allowed, if it determines that a
lower standard is required because of density of population or land use, age or
type of structure, geology or hydrology of the area, frequency of the vibration
or other factors.
(i) The maximum
peak particle velocity limitation of subsection (h) does not apply at
structures located on the permit area when the owner and lessee, if leased to
another party, of the structure have each signed a waiver releasing the
vibration limit. The waiver shall be clear, knowing and specific. This waiver
shall be submitted to the Department prior to the firing of a blast which
exceeds the current vibration limit, as stated in this section or the blast
plan.
(j) When seismographs are not
used to monitor peak particle velocity, the maximum weight of explosives to be
detonated within an 8 millisecond period may be determined by the formula W =
(D/Ds)2 where W equals the maximum weight of
explosives, in pounds, that can be detonated in any 8 millisecond period or
greater, D equals the distance, in feet, from the blast to the nearest
dwelling, school, church, commercial or institutional building and Ds equals
the scaled distance factor . The development of a modified scaled-distance
factor may be authorized by the Department 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 so that the particle
velocity of the predicted ground vibration will not exceed the prescribed
maximum allowable peak particle velocity of subsection (n) at a 95% confidence
level.
(k) When a seismograph is
used to monitor the peak particle velocity, a seismograph record shall be
obtained for each blast and within 30 calendar days become part of the blast
record required in §
87.129 (relating to use of
explosives: record of blasting operations). The seismograph record shall be
analyzed by an independent party qualified in the analysis of seismic
data.
(l) The Department may
require a seismograph record of blasts and may specify the location at which
the measurements are taken.
(m) The
maximum ground vibration may not exceed the following limits at the location of
a dwelling, public building, school, church or community or institutional
building:
Distance (D), from the blasting site, in
feet
|
Maximum allow-able peak particle velocity (Vmax)
for ground vibration, in inches/second1
|
Scaled-distance factor to be applied without seismic
monitoring (Ds)2
|
0 to 300 |
1.25 |
50 |
301 to 5,000 |
1.00 |
55 |
5,001 and beyond |
.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 subsection (j).
(n) The Department will not permit blasting
to be conducted until:
(1) Blasting plans,
under §
87.64 (relating to blasting plan),
are approved by the Department and the approved blasting plan is returned to
the operator.
(2) Notification of
completion of requested preblasting surveys, under §
87.125 (relating to use of
explosives: preblasting survey), is received by the Department.
(3) Copy of the proof of publication of each
blasting schedule, under §
87.126 (relating to use of
explosives; public notice of blasting schedule), is received by the
Department.
(o) An
operator may use Figure 1, the blast level chart, to determine the maximum
allowable ground vibration. If Figure 1 is used, the operator shall provide a
seismograph record including both the particle velocity time-history (wave
form) and the particle velocity and vibration frequency levels for each blast.
Click to view image
(1) The vibration frequency shall be
displayed and analyzed over the frequency range of 1 Hz through 100
Hz.
(2) The permittee shall obtain
Department approval of the analytical method used to determine the predominant
frequency before applying this alternative criterion.