The following words, terms and phrases, when used in this chapter,
shall have the meanings ascribed to them in this section, except where
the context clearly indicates a different meaning:
AIRBLAST
An airborne shock wave resulting from detonation of explosives.
Airblast may be caused by burden movement or the release of expanding
gas into the air. Airblast may or may not be audible.
APPLICANT
The owner or other individual, corporation or other business
entity who or which applies for the legal right to conduct blasting
at real property which it has the legal right to use.
BLAST SITE
The area where explosive material is handled during the loading
of drilled blastholes, including the perimeter formed by the loaded
blastholes and 50 feet in all directions from loaded blastholes [see
38 M.R.S.A. § 490-W(5)].
BLASTER
An applicant who has been awarded a permit to conduct blasting.
BLASTING
The use of explosives to break up or otherwise aid in the
extraction or removal of rock or other consolidated material.
BLASTING OPERATIONS
All processes conducted in association with site or other
preparation for blasting, and the detonation of explosives.
DECIBEL
The unit of sound pressure commonly used to measure airblast
from explosives. The decibel scale is logarithmic.
EXPLOSIVES
Any substance, chemical compound or mechanical mixture that
is used for the purpose of producing an explosion to fragment rock
for mining, quarrying, excavation and construction. Initiating devices
(detonators, detonating cords, etc.) are also included under this
definition.
FLYROCK
Rock that is propelled through the air or along the ground,
which leaves the secured blast area as a result of the detonation
of explosives.
GROUND VIBRATIONS
Shaking of the ground caused by blasting. Ground vibrations
are to be measured along three principal axes (x, y, z); namely, transverse,
vertical, and longitudinal, all of which are subject to the performance
standards herein.
GROUNDWATER
Water beneath the earth's surface often between saturated
soil and rock that supplies wells and streams.
HERTZ
A term used, in the case of blasting, to express the frequency
of ground vibrations and airblast. One hertz is one cycle per second.
PARTICLE VELOCITY
A measure of ground vibration in the case of blasting. Particle
velocity describes the velocity at which a particle of ground vibrates
when excited by a seismic wave. It is measured in inches per second.
PRODUCTION QUARRY
A quarry where the primary use of the quarry is to produce
material for commercial sale or beneficiation. The distinguishing
characteristic is that the quarry is not being operated in association
with an approved and permitted on-site development or construction
project.
QUARRY
The property designated in the application and permit where
rock is excavated [see 38 M.R.S.A. § 490-W(17)].
SEISMOGRAPH
An instrument that measures and has the capability to provide
a permanent record of hertz and decibel readings concerning ground
vibrations caused by blasting.
All blasters must comply with the following performance standards:
A. Hours of detonation.
(1) Production quarry. As stipulated by the Planning Board, or as required by Chapter
198, Article
I, Mineral Extraction, of the City Code, which allows production blasting between 11:00 a.m. and 3:00 p.m., Monday through Saturday, with the exception of New Year's Day, Memorial Day, the Fourth of July, Labor Day, Thanksgiving Day, and Christmas Day. Emergency blasting for misfires shall be allowed after the 3:00 p.m. cutoff time, provided that the City and abutters are notified prior to detonation.
[Amended 9-4-2014 by Ord.
No. 14-148]
(2) All other blasting. Hours of detonation are limited to between sunrise and sunset or between 7:00 a.m. and 7:00 p.m., whichever is greater, Monday through Friday inclusive, except by special exception as allowed under §
130-9 of this chapter. In no case shall a blast occur on the following legal holidays: New Year's Day, Memorial Day, Fourth of July, Labor Day, Veterans Day, Thanksgiving and Christmas. Blasting which occurs as part of a mineral extraction license must occur between 11:00 a.m. and 3:00 p.m. pursuant to Chapter
198, Article
I, Mineral Extraction, §
198-8B(9)(b), of the Code of Ordinances.
[Amended 7-17-2014 by Ord. No. 14-108]
(3) Emergency situations. Blasting of any type may occur at any time
in situations deemed to be emergencies by the Bureau of Code Enforcement,
after possible consultation with other City staff. Emergency situations
may include, but are not limited to, blasting to install utilities
damaged by weather events or blasting to correct a misfire of explosives
in an otherwise permitted blast event.
B. Water quality protection. Water is a precious resource and the applicant
must take measures to assure that the quality of the groundwater is
protected. Prior to the initial blast, the applicant must conduct
water quality tests on all non-applicant-owned wells within 300 feet
of the property line or as determined by the Planning Board for production
blasting and Planning Board approved projects. Water quality testing
must also be done post-blast if requested by the property owner because
of evidence of a substantive change in water quality. Turbidity in
wells tested shall be no greater than that which existed prior to
the blasting as established in the pre-blast survey.
C. Ground vibration.
(1) Peak particle velocity. Peak particle velocity limits (inches per
second) not to be exceeded at any time, and in any one of the three
principal directions:
(a)
Production quarry:
|
Distance From Blast
(feet)
|
Maximum Peak Particle Velocity
(inches/second)
|
---|
|
Less than 300
|
1.25
|
|
300 to less than 500
|
0.94
|
|
500 to less than 5,000
|
0.75
|
|
5,000 or more
|
0.54
|
(b)
Other.
Source: U.S. Bureau of Mines USBM RI 8507, 1980
|
[1]
Up to 30 hertz: 0.5 inch per second.
[2]
Thirty to 40 hertz: 1.0 inch per second.
[3]
More than 40 hertz: 2.0 inches per second.
(2) Measurement. Ground vibration shall be measured as particle velocity.
Particle velocity shall be recorded in three mutually perpendicular
directions (x, y, z). The maximum allowable peak particle velocity
shall apply to each of the three measurements.
(3) Seismographic record. A seismographic record for all blasts shall
be retained by the applicant and provided to the Bureau of Code Enforcement
or the Planning Board, if requested. The applicant is responsible
for such record and for providing proper instrumentation as specified
in this chapter. Personnel conducting such monitoring shall be properly
trained in the operation of the equipment being used.
D. Airblast overpressure. Level not to be exceeded at any time: 133
peak dB (linear) two hertz high-pass system.
E. Instrumentation. All seismographs used for compliance with this chapter
shall meet the following minimum specifications:
(1) Seismic frequency range: two Hz to 200 Hz (±three±
Hz).
(2) Acoustic frequency range: two Hz to 200 Hz (±one± dB).
(3) Velocity range: 0.02 inch to 4.0 inch per second.
(4) Sound range: 110 dB to 140 dB linear.
(5) Transducers: three mutually perpendicular axes.
(6) Recording: provide time-history of waveform.
(7) Calibration: laboratory-calibrated as often as necessary, but at
least once every 12 months or according to manufacturer's recommendations,
whichever is less.
(8) Measurements. The requirements established herein shall be measured
at the closest building(s) on abutting properties as determined by
the Code Enforcement Officer or Planning Board.
F. Other permits. The applicant must also comply with all standards
and conditions contained in other permits issued for such projects
and local, state and federal statutes and regulations.
[Amended 10-1-2009 by Ord. No. 123]
A. Penalties. The submission of willful false information required by
this chapter, or the violation of this chapter or the violation of
any condition attached to a permit granted under this chapter shall
constitute a land use violation for which an enforcement action may
be commenced by the City in accordance with 30-A M.R.S.A. § 4452.
B. Reporting. A copy of the violation report and consent agreement reached
between the City and the person or entity found in violation of any
portion of this chapter will be filed in the permit or license file
and the same shall be reported in writing to the City Council.