Current through Register Vol. 48, No. 12, March 22, 2024
a) 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 ground or surface water outside the permit
area.
b) Air blast limits
1) Air blast shall be controlled so that it
does not exceed the values specified below at any dwelling, public building,
school, church, or commercial or institutional structure, unless such structure
is owned by the person who conducts the surface mining activities and is not
leased to any other person. If a building owned by the person conducting
surface mining activities is leased to another person, the lessee may sign a
waiver relieving the operator from meeting the air blast limitations of this
subsection. The waiver shall be submitted to the Department before beginning
blasting.
Lower frequency limit of measuring system, Hz
+3dB
|
Maximum
level in dB
|
0.1 Hz or lower - flat response*
|
134 peak
|
2.0 Hz or lower - flat response
|
133 peak
|
6.0 Hz or lower - flat response
|
129 peak
|
* Only when approved by the Department
|
2) The
measuring systems used shall have a flat frequency response of at least 200 Hz
at the upper end.
3) The person who
conducts blasting may satisfy the provisions of subsection (b) by meeting any
of the three specifications in the chart in subsection (b)(1).
4) If necessary to prevent damages specified
in subsection (a), the Department shall specify lower maximum allowable
airblast levels than those in subsection (b)(1) for use in the vicinity of a
specific blasting operation.
c) Air blast monitoring
1) When the cube root scaled distance, as
defined in subsection (c)(2), to the nearest dwelling, public building, school,
church, or commercial or institutional structure has a value less than 350 and
when the burden to hole depth ratio is greater than 1.0, or the top stemming
height is less than 70% of the burden dimension, the air blast produced by that
blast shall be measured, recorded, analyzed, and reported pursuant to
subsection (g) of this Section and Section
1816.68(b).
This subsection shall not apply to horizontal blast holes drilled from the
floor of the pit.
2) Cube root
scaled distance equals the distance, in feet, from the blast to a specified
location divided by the cube root of the maximum weight of explosives, in
pounds, to be detonated in any eight millisecond period.
3) To ensure compliance with the limits
contained in this Section, the Department may require an air blast measurement
of any or all blasts, and may specify the location of such
measurements.
d)
Flyrock, including blasted material traveling in the air, or along the ground,
shall not be cast beyond the permit boundaries or beyond the area of regulated
access required under Section
1816.66(c),
or more than one-half the distance to the nearest dwelling or other occupied
structure.
e) Ground vibration
limits
1) In all blasting operations, except
as otherwise authorized in this Section, the maximum peak particle velocity
shall not exceed one inch per second at the location of any dwelling, public
building, school, church, or commercial or institutional building. At distances
greater than 5,000 feet from the blast to any structures described in this
subsection, the maximum allowable peak particle velocity shall not exceed 0.75
inch per second at the locations of the structures described in this
subsection. At distances less than 300 feet from the blast to any structures
described in this subsection, the maximum allowable peak particle velocity
shall not exceed
1.25 inch per
second at the locations of the structures described in this subsection. These
limits shall apply separately to each component of motion as defined in
subsection (g). The Department shall reduce peak particle velocity limits if
determined necessary to provide damage protection, if so recommended in any
pre-blast survey or condition survey report provided pursuant to Section
1816.62.
2) Blasting shall be conducted to prevent
adverse impacts on any underground mine and changes in the course, channel, or
availability of ground or surface water outside the permit area. Ground
vibration limits, including the maximum peak particle velocity limitation of
subsection (e)(1), shall not apply at the following locations:
A) At structures owned by the person
conducting the mining activity, and not leased to another party; and
B) At structures owned by the person
conducting the mining activity, and leased to another party, if a written
waiver by the lessee is submitted to the Department prior to
blasting.
f)
Ground vibration monitoring
1) When the scaled
distance, as defined below, has a value less than 65 at the nearest dwelling,
public building, school, church, or commercial or institutional structure, a
seismograph recording shall be made at or near the closest structure requiring
protection.
2) Scaled Distance =
The distance, in feet, from the blast to a specified location divided by the
square root of the maximum weight of explosives, in pounds, to be detonated in
any eight millisecond period.
3) To
ensure compliance with the limits contained in this Section, the Department may
require a seismograph recording of any or all blasts and may specify the
location at which such recordings are made.
g) As used herein, seismograph recording or
record or air blast recording or record shall mean:
A visually inspectable cartesian representation of the time
history of the particle velocity levels or air blast levels versus time. Time
is represented on the "X" axis. The particle velocity is shown by three traces
representing mutually perpendicular components of motion. The components are
oriented vertically, transversely, and longitudinally to the horizontal
direction from the recording location to the location of the blast. The air
blast time history is represented by a single trace. The record or recording
includes either an analog representation of, or a written description of the
vertical scale for the particle velocity traces and the air blast trace. The
units for the particle velocity traces and scale are in inches per second. The
units for the air blast trace and scale are millibars, pounds per square inch,
or decibels. The recording also includes an analog or descriptive time scale.
The time units are in seconds.