FEATURE
and seriously annoyed at continuous sound levels above 55
dB(A).
Pile driving is one of the noisiest construction operations.
Figure 2 shows a range of sound levels reported for pile driving
for a variety of hammer types and sizes. For the noisiest
hammer, one would have to go approximately 300 feet away
from the hammer to get below the OSHA eight-hour exposure
limit. One would have to get several miles away from the
noisiest hammer for the sound level to drop below that, causing
moderate annoyance to most people. Clearly, pile driving
in suburban areas has the potential to annoy a lot of people.
When people become annoyed, they also become concerned.
They start looking for evidence of damage to their property
from the construction work and complaining to their elected
officials. Some engage lawyers to pursue compensation for
their grief. When people look for evidence to confirm their
suspicions, they will usually find something. Politicians don’t
like receiving complaints. Lawyers love opportunity. Noise
may be the most serious threat to the pile driving industry
today – not because it is causing damage, but because it creates
a perceived problem to those impacted.
Vibration and noise from pile driving have some common
elements. The intensity of both decreases with the log of
distance away from the source. Both are unlikely to cause
structural damage as long as the structure is several feet from
the driving activity. For both, the real problem is the annoyance
to people caused by the vibrations and the noise, and
not physical danger.
In today’s urban world, people demand a secure environment
free from annoyance. Contractors must develop means
to manage the vibration and noise problems produced by
pile driving. The following approaches are recommended for
every project that involves pile driving:
1. Education: People that may be impacted by pile driving
need to be informed in advance of the planned activities
and what the impact to them may be. Informed people
are less likely to suspect that the vibrations and noise are
causing physical harm to themselves or their property.
People potentially impacted should be provided with
educational materials on the project schedule, the nature
of the work, the importance of the work to the community
and the potential impacts of the work on them. A
special effort should be made to assure them that feeling
vibrations and hearing noise does not equate to physical
harm or damage. Be considerate and respectful of their
expected right to a peaceful environment.
2. Abatement: Take steps to reduce vibration and noise
levels to the extent that they are economically possible.
Limit the time of driving to daylight hours when people
are less affected by these nuisances. Try to reduce the time
required for pile driving. Use noise shrouds or curtains to
reduce noise levels by 15 to 30 dB(A). Figure 2 shows that
a 30 dB(A) reduction to the noisiest hammer can limit the
area within which most people are moderately annoyed to
within 500 feet of the work!
3. Monitoring: Measure the noise and vibration levels at key
locations. Use the measured data with the information in
this article to demonstrate that your work is well below
the levels that cause harm. Actual measurements can
People can feel and become
concerned about vibrations
that are only a tiny fraction
of those that might begin to
cause damage to structures.
People complain about pile
driving effects because they
are much more sensitive to
vibrations than buildings are.
become invaluable if you face a legal action over vibration
or noise complaints. Should the measurements show
unacceptable performance, adjust your work processes
to correct the problem before someone else complains.
Measurements should begin before pile driving starts
to establish background levels of vibration and noise.
Preconstruction damage surveys may be worthwhile
where buildings are located within a few hundred feet of
pile driving activities.
4. Involvement: Keep the affected parties engaged in the
project and informed of progress. Use community representatives,
meetings, newsletters or a project webpage.
Use the measurements from your monitoring program
to show how well you are keeping vibrations and noise at
safe levels.
5. Proactive: Stay proactive to manage vibrations and noise
and minimize information. After all, vibrations and noise
from pile driving are more perceived problems than they
are reality. But as the modern world acts, perception is
reality, so you have to work to manage the perception.
We have been working on some technology to help contractors
carry out these approaches. It involves the use of
vibration and sound monitoring equipment connected to
the Internet. We provide special seismographs to a contractor,
who places them at special locations. The seismographs
are coupled to the Internet via a cell phone. The system is
programmed to call our server whenever a preset threshold
of vibration or sound is recorded. Our server downloads the
specific data from the seismograph and places it onto a website.
Our server may also send an email or coded message by
phone or pager to the contractor to alert them that threshold
levels for vibration or noise are being exceeded. All of this
happens automatically and within a few minutes.
This article originally appeared in the Quarter 3 2015 issue
of PileDriver magazine, the flagship publication of the Pile
Driving Contractors Association (www.piledrivers.org). It is
reprinted with permission.
PILING CANADA 47
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