HomeMy WebLinkAbout2024-11-04-NAC-min
Town of Lexington, MA
Noise Advisory Committee (NAC)
Minutes of Meeting, November 4, 2024
Town of Lexington
Noise Advisory Committee (NAC)
Minutes of Meeting, November 4,2024
The meeting of the Noise Advisory Committee (“NAC”) was held in person in the Hudson Room
of Cary Hall and on Zoom on Monday, November 4, 2024 and called to order at 7:04 PM.
NAC Members Present: Barbara Katzenberg (Chair) (BK), Sallye Bleiberg (SB), Benjamin
Lees (BL), Laura Rosen (LR), Elaine Rudell (ER)
Absent: Joe Pato (Select Board Liaison)
Introduction and Administration
1. ER was assigned as Clerk for this meeting
2. Minutes of the October 1 2024 meeting were approved unanimously with some agreed
to modifications
Committee Business
Announcements
Homeowners of Fiske Commons Condos-rescinded request to Select Board for a
special permit for use of gas-powered leaf blowers (GLBs) past phaseout date
o Previously presented concerns regarding handling their landscaping
needs without GLBs. Requested a waiver from the Select Board
o In the interim, they found a contractor who could do the work for a
reasonable price and withdrew their request.
Hanscom Field Private Jet Expansion –proposed updates to Massport charter
o BK reminded NAC that Lexington cannot enforce the Noise Bylaw in
relation to Hanscom Field activities
o BK provided an update on work happening to pass a Climate Bill in the
MA state legislature. The proposed bill includes language to update the
Massport charter to require consideration of environmental impacts.
Discussion about the Process and Implementation of Noise Mitigation Plans
for Ledge Work—Guests Lawrence G. Copley, noise mitigation and acoustics
specialist (LC) and James Kelly Building Commissioner (JK)
At the 2024 Annual Town Meeting, the Noise Bylaw was amended to
require that for a project that has more than 7 days of ledge work, a
certified noise mitigation expert be employed to create a mitigation plan
before a building permit can be issued.
LC began by defining his role: to assist the contractor in complying with
the town bylaws and regulations (as well as State)
o First step with the contractors: he goes to the site to (1) get an
understanding of what they want to do, (2) what neighbors are in
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the area and how close they are, (3) how they plan to remove the
ledge and the equipment they plan to leave (he might measure the
noise from that particular footage), (4) kick around ideas to
mitigate the noise
o Next step is to prepare the site plan showing the ledge work area,
proposed new buildings, and nearby residential buildings; plan will
also address ways to mitigate the noise
o The site plan is then submitted to JK’s office (Office of Lexington
Building Commissioner) to obtain his feedback; generally, Jim
asks for a couple of changes and we’ve always made these
changes.
o After the project has started, LC comes out to conduct noise
monitoring, as needed.
What are noise mitigation methods?
o No quiet ways to remove ledge.
o Ideally, design construction to minimize the need for ledge work;
this was done more often in the past. Example of incorporating
ledge into design without removing it is Moon Hill neighborhood.
Consider an architectural review committee for certain
neighborhoods?
o Barriers can mitigate-- the only available approach. Examples
include:
Portable noise barriers--take the edge off.
Create berms (mounds of earth) that act as a barrier; can
do when excavating for a basement, where you have
“spare” earth – instead of taking it off site. Not feasible for
small lots where houses are close to each other).
What are the methods for ledge removal?
o Hammering
o Splitting rock. Requires drilling a hole in the rock which also
creates noise, and the noise comes in quite high up so you can’t
really shield it.
o Blasting: Sounds worse than it is, over quickly compared to other
methods (gives example of the demolition of a building at
Dartmouth College)
What are other disruptive types of construction noise?
o Backup alarms: constant, annoying, start early. New type of
backup sound (e.g. Amazon delivery trucks) that produces a
“whoosh” sound instead of the alarm. There are also “self-
adjusting” backup alarms that modulate depending on ambient
level (e.g. at 6:30 AM, when it is quiet, the loudness would be
reduced). Discussion about opportunity to request and have
contractors change alarm type. Currently contractors are limited in
hours of work but will arrive early and back up their trucks before
that time.
o Generators: Rare at construction sites, most Lexington contractors
get a temporary power hook up. BK: Movie producers using
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Lexington location may need a generator; however most will
reimburse neighbors for the annoyance.
What is effective noise mitigation? Limited options for small lot (1/4 acre)
– there isn’t room to provide an earth berm because houses are very
close
Are the decibel levels in the bylaw adequate to protect people? 85
decibels at the property line is very loud. Maybe chosen because 85
decibels is the threshold for noise induced injury for workers. But,
realistically, hard to do better than that on a small site if you are going to
allow ledge hammering.
Do you know any municipalities that don’t allow ledge hammering? No.
It’s a balancing act. It would be pretty extreme to not allow ledge work.
Would it be reasonable to limit the total number of days of ledge work?
Discussion about Rye NY which limits the total number of allowed days of
ledge work and also limits doing additional ledge work within 180 days of
the first work. Bob Pressman raises his understanding that Rye NY even
controls the allowable start date for a second instance of ledge work in
the same neighborhood for a separate, unrelated project.
Can you mitigate the noise of rock crushing (breaking large pieces of rock
into smaller pieces)? JK: At 69 Pleasant Street we had it all: the blast, the
drill, the hammers, the crush, the trucks with the backup alarms. The
crusher when we measured it wasn’t that loud by decibel level. But, the
dropping of the rocks into the crusher was unbelievably loud. (LC:
sometimes they line a bin with rubber to reduce the noise). Even if rock
crushing is to be performed off site, some on-site break up of large rocks
so they can fit in the truck will be needed.
LC Hardness of rock can affect how long hammering is needed and
blasting should be considered for purple rock (extremely hard rock). The
ledge around this area is somewhat fractured and is easier to break up.
Vibrations associated with blasting upsets people.
o Bob Pressman: In a proposed housing projects on Concord Ave to
be built on ledge, there is a daycare center within 300’ and
children’s school in close proximity. Not ideal to have noise &
vibration all day long under these conditions.
o LC: Pre-blasting surveys, seismographs to measure vibration.
State allows 2” per second and that’s a lot. But unless the plaster
in your house is fragile it tolerates it. But it feels awful, like your
house is going be destroyed.
o BK: Notes that the vibration of ledge work is not governed by the
Noise Bylaw, only the noise.
o JK: Thinks Lexington reduces state limits to 1” but would need to
check with Fire Chief; the argument against this lowered level is
that it takes longer. Thinks Lexington Fire Department has
achieved a good balance.
o People within 250 feet of a blasting site are entitled to a
preconstruction survey of their property involving a video of their
home (also required by the blasting company’s insurance
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company). Mr. Kelly indicated that he asked for preconstruction
(blasting) surveys to be expanded to 300 feet (involving more
homes). Blasting is a heavily regulated industry from the State
Fire Marshalls’ Office,
o JK: Site-specific- you have a smaller area of ledge work you may
try to convince the homeowner to incorporate the ledge into the
crawl space. Start earlier in the planning process – when a home
is being designed, do soil testing and investigate the site.
Excavated soil can act as a barrier to the noise if the noise is well
below that level.
o LR: In the Meriam project, the construction was on a hill and the
soil was below the level where the noise was generated. In that
situation, the neighbors adjacent to the noise, were provided with
Wilson Farm baskets to say “Thank you for your patience!”
BK: Are our methods & metrics for assessing noise appropriate? Are
there methods that are more sophisticated/nuanced? Are the maximum
noise levels appropriate? 85 decibels? What about L10?
o LC: Currently the bylaw has a limit of 85 decibels as a goal, but
duration is an issue too. With L10, you monitor for a period (e.g.,
20 minutes) and the instrument calculates what’s the level
exceeded 10% of the time. So towards the upper end of the
variation. The other method is Leq-just as valid, a little easier to
measure, most instruments will do. It’s the energy level equivalent
to the sound level
BK: We can measure sound, but that doesn’t necessarily measure how
people experience it. Are their better metrics than decibels to represent
how people experience noise?
o <question not answered>
BL: Would it make sense to change measurement methods so that limits
take the length of time into account; Are activities that go on longest less
loud?
o LC: If they use a more powerful hammer it won’t take as long, it
might take fewer days, but they are still going to work all day.
o LC: One possible improvement to the bylaw would be to measure
at the abutting house not the property line. I threw out the idea of
75 decibels at the exterior of the house, which would end up being
about 60 decibels inside. If the house is 15 feet from the property
line it won’t make that much of a difference, but at 30-40’ you get
some benefits.
o JK: Hammering is bad. You can try to mitigate. You can go inside
your house. But it’s just an awful tool to use to break the earth up
into small pieces. We were recently able to convince people to
change from hammering to blasting for a project. Convince the
neighbors to let the folks doing the video survey to come in. Ask
the company to share the video.
o JK: For neighbors knowing how long it will take can help.
Sometimes the contractors don’t know or they don’t want to know.
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Saying 15 days may not be good, but it’s better than saying it
might be a week, might be 2, and then it turns into 4.
o LR: Why not pay for people to stay in a hotel. The cost to them is
minimal.
BK: How many projects have required a mitigation plan since the update
to bylaw. Does it result in fewer complaints, etc.?
o JK: There have been 3. So far, it is helpful, contractors are aware
of it early in the development process. Good to have a responsible
professional to measure. It will prevent it from being > 85 but that
is still very aggravating for the neighbors. But eventually it goes
away (unlike, noisy HVAC equipment at top of a roof 24/7).
Bob Pressman: Stop the project if it goes over 7 days without a plan?
o JK: Yes. But we try not to let that happen. If people are getting
close to 7 days and don’t have a noise mitigation plan, we say
they should engage a progressional now. The cost of a fine won’t
stop them, but stopping the project will.
BK: I was hoping there was some new technology out there that would be
a magic bullet, but this discussion has been helpful
o LC: I wish there was a technology to reduce, but I don’t think there
is. But happy to hear JK thinks the bylaws have been helpful
Noise Bylaws in Other Massachusetts Municipalities Quincy (LR review)
The only specific mention of leaf blowers is under the definition of continuous
noise, but nowhere… in their bylaws or in their ordinance” (continuous noise
refers to anything that generates that noise – such as woodchippers, chain saws,
etc.). In addition they have
o a section on construction
o noise suppression plan – may be comparable to Lexington’s noise
mitigation
o “noise sensitive areas” where there are even more intense restrictions
(e.g. hospitals) – exemptions do not apply to landscape equipment
o 5 categories of maximum allowable limits – whether in residential or
nonresidential areas, day or night, limits are <85 decibels (it is thought
these related to “everyday noise” we may generate)
o Construction noise levels must be measured at the location at a distance
of no more than 50 feet from the source (85 decibels noted here)
Public Comment (Martha D.) It is not just landscapers who used GLBs, but also
they are used for cleanup at construction sites. Does the Noise Bylaw cover these?
Also note that despite being not allowed in the summer many landscapers continued
to use GLBs.
Adjourn The meeting was adjourned at 8:40 PM (approximate). The next meeting is December
3 2024, at 7pm.
Respectfully submitted,
Elaine Rudell
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