N.D. Admin Code 69-05.2-17-05 - Performance standards - Use of explosives - Surface blasting procedures
1. All blasting
must be conducted between sunrise and sunset, unless nighttime blasting is
approved by the commission upon a showing by the operator that the public will
be protected from adverse noise and other impacts. The commission may specify
more restrictive time periods for blasting.
2. Blasting must be conducted at the
scheduled times, except in those unavoidable hazardous situations, previously
approved by the commission in the permit application, where operator or public
safety require unscheduled detonation.
3. Warning and all-clear signals of different
character that are audible within a range of one-half mile [0.85 kilometers]
from the point of the blast must be given. Each person within the permit area
and each person who resides or regularly works within one-half mile [0.85
kilometers] of the permit area must be notified of the meaning of the signals
through appropriate instructions. Recipients must be periodically and clearly
informed of the meaning of the signals. Signs must be maintained according to
subsection 6 of section
69-05.2-13-04.
4. Access to an area possibly subject to
flyrock from blasting must be regulated to protect the public and livestock.
Access to the area must be controlled to prevent the presence of livestock or
unauthorized personnel during blasting and until an authorized representative
of the operator has reasonably determined that:
a. There are no unusual circumstances, such
as imminent slides or undetonated charges; and
b. Access to and travel in or through the
area can be safely resumed.
5. Airblast must be controlled so that it
does not exceed the values in this subsection at any dwelling, public building,
school, church, or commercial or institutional structure, unless the structure
is owned by the operator or permittee and is not leased to any other person. If
a building owned by the operator or permittee is leased to another person, the
lessee may sign a waiver relieving the operator from meeting the airblast
limitations of this subsection.
Lower frequency limit of measuring system, Hz (plusmn;3dB) | Maximum level in 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. |
a. In all cases
except the C-weighted, slow response, the measuring systems used must have a
flat frequency response of at least two hundred Hz at the upper end. The
C-weighted case must be measured with a type 1 sound level meter that meets the
standard American national standards institute (ANSI) S1.4-1971 specifications.
b. The person who conducts
blasting may satisfy the provisions of this subsection by meeting any of the
four specifications in the chart in this subsection.
c. The operator shall conduct periodic
monitoring to ensure compliance with the airblast standards. The commission may
require an airblast measurement of any or all blasts, and may specify the
location of the measurements.
d.
If necessary to prevent damage, the commission will specify lower maximum
allowable airblast levels than those of this subsection for use in the vicinity
of a specific blasting operation.
6. Flyrock, including blasted material
traveling along the ground, may 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 subsection 4.
7. Ground vibrations.
a. In all blasting operations, except as
authorized in subdivision e, the maximum ground vibration may not exceed the
values approved in the blasting plan. The maximum ground vibration for
structures listed in subdivision b must be established according to the maximum
peak particle velocity limits of subdivision b, the scaled-distance equation of
subdivision c, or by the commission under subdivision d. All structures in the
vicinity of the blasting area not listed in subdivision b must be protected
from damage by a maximum allowable limit on the ground vibration, submitted by
the operator in the blasting plan and approved by the commission.
b. The maximum ground vibration may 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/second | Scaled-distance factor to be applied without seismic monitoring (Ds) |
0 to 300 | 1.25 | 50 |
301 to 5000 | 1.00 | 55 |
5001 and beyond | 0.75 | 65 |
A seismographic record must be provided for each blast.
c. Scaled-distance
equation.
(1) 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 eight-millisecond
period without seismic monitoring, where W = the maximum weight of explosives
in pounds; D = the distance, in feet, from the blast site to the nearest
protected structure; and Ds = the scaled-distance
factor, which may initially be approved by the commission using the values for
scaled-distance factor listed in subdivision b.
(2) 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 minesite. The factor must ensure that the particle velocity will not
exceed the prescribed maximum allowable peak particle velocity of subdivision b
at a ninety-five percent confidence level.
d. The maximum allowable ground vibration
will be reduced by the commission beyond the limits otherwise provided by this
section if determined necessary to provide damage protection.
e. The maximum airblast and ground-vibration
standards of this subsection do not apply at structures owned by the permittee
and:
(1) Not leased to another person.
(2) Leased to another person if a
written waiver by the lessee is submitted to the commission before blasting.
Notes
General Authority: NDCC 38-14.1-03
Law Implemented: NDCC 38-14.1-24
State regulations are updated quarterly; we currently have two versions available. Below is a comparison between our most recent version and the prior quarterly release. More comparison features will be added as we have more versions to compare.
No prior version found.