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)].
BLAST SIZE
A.
Small blast: trench blast or under 50 cubic yards of rock removed.
B.
Medium blast: removal of 50 to 300 cubic yards of rock material.
C.
Large blast: removal of over 300 cubic yards of rock material.
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.
EXTRACTIVE INDUSTRY
Any operation engaged in the removal of more than 20 cubic
yards, in a twelve-month period, of topsoil, sand, gravel, clay, rock,
peat or other like material from its natural location and for transportation
off lot within any twelve-month period, except as may be exempted
within the extractive industry performance standards in this chapter.
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.
QUARRY
The property designated in the application and permit where
rock is excavated in an extractive industry operation.
SECURED BLAST AREA
The area that may be affected by flyrock, dust, or fumes
from an explosion that may cause personal injuries, damages to property,
or losses in the process. The minimum distance for personnel is 500
feet. Safe distances will be determined based on conditions for each
blast by the blasting foreman or designee.
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 shall comply with the following performance standards:
A. Hours of detonation.
(1) Earth removal operation. As stipulated by the Planning Board in conjunction with §
230-702.
(2) All other blasting. Hours of detonation are limited to between sunrise
and sunset but no earlier than 8:00 a.m. and no later than 8:00 p.m.,
Monday through Friday inclusive.
(3) Emergency situations. Blasting of any type may occur at any time
in situations deemed to be emergencies by the Code Enforcement Department,
after consultation with other City staff as may be determined to be
necessary by Code Enforcement personnel. 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 distances outlined in §
71-4H above. 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 at a structure location:
(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.
[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 Code Enforcement
Department 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 inches 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.
Blasting in Saco shall be conducted in compliance with all pertinent
section of the City Code of Ordinances, and, except as superseded
by the provision of this article, the NFPA 1 Fire Prevention Code,
and NFPA 495 Explosive Materials Code as adopted by the State of Maine.
In any particular instance where these regulations are in conflict
with any other rules, regulations or ordinances of the City, the more
restrictive regulation or provision shall prevail.
If the Code Enforcement Department has denied a blasting permit
under this article, the applicant may appeal the denial to the Zoning
Board of Appeals within 30 days of the decision by filing a written
notice of appeal.