3.3.5.2
Mechanical Presplitting
Drill holes of size and spacing as recommended by the manufacturer for the
conditions present. Insert and operate mechanical splitters in accordance
with the manufacturer's instructions.
3.3.6
Controlled Blasting
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NOTE: Blasting may result in microfracturing of the
concrete which remains. Additional concrete removal
by other methods such as hand-held breakers or
high-pressure water may be required to remove some
of the microfractured concrete.
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3.3.6.1
General
Controlled blasting shall consist of a systematic process of sawcutting,
drilling, loading and blasting to break the concrete on a controlled plane.
Submit a detailed blasting plan in accordance with paragraph SUBMITTALS.
All use of explosives shall be subject to prior approval of the Contracting
Officer. Do not deviate from the approved plan without authorization of
the Contracting Officer. After blasting, submit an "as-built" blasting
plan showing any approved changes. Approval of the Contractor's blasting
plan shall not relieve him of responsibility for any damages or injuries
resulting from blasting.
3.3.6.2
Safety
Handle, store, and use explosives in accordance with applicable provisions
of the EM 385-1-1 and state and local regulations. All blasting work shall
be at the risk and responsibility of the Contractor. Conduct all blasting
operations with due regard to the safety of persons in the vicinity and
traffic passing the site. Make provisions for warning personnel and
traffic in advance of blasting.
3.3.6.3
Procedure
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NOTE: The suggested peak particle velocity applies
to concrete adjacent to structures which are to
remain. The permissible peak particle velocity
should be determined based on the existing materials
and conditions to avoid damage to structures and
equipment to remain.
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Determining the diameter, depth and spacing of holes, and loading, delays
and stemmings for explosives. Drill holes with equipment competent to
maintain the alignment and plane of the drill hole pattern throughout the
full depth of the holes.
Limit extent of blasting area and use delays as
required, to prevent damage to the structure. Peak particle velocity shall
not exceed [50] [ ] mm ([2] [ ] inches)[2] [ ] inches per second.
Airblast pressure shall not exceed 0.7 kPa (0.1 psi)0.1 psi. Should
vibration exceed the specified limits, modify the blasting plan as
required, subject to approval by the Contracting Officer. Use detonating
cord as explosives. Use blasting mats as necessary to control flyrock and
contain debris.
SECTION 03931
Page 54
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