g. When DOB regulations require a perimeter barrier
or "construction fence", and the site is within 200 feet of a
receptor or a receiving property as defined in sec.28-109 of this
chapter, perimeter noise barriers shall be fabricated in accordance
with the standards set forth in subdivision e of sec.28-107 of this
chapter and lined with material set forth in subdivisions c and e of
sec.28-107 of this chapter. Further, the responsible party shall
fill in any gaps and holes in adjacent panels of noise barriers with
noise attenuation material, so as to maximize the effectiveness of
such barriers. Such noise attenuation material shall include
noise curtain material, additional plywood, or similar material.
When viewing ports are required in the curtain material, they shall
be filled in with clear plastic attached to the curtain.
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a. Portable
noise enclosures (so-called "noise tents") made of
steel frames wrapped with noise curtain material,
such as SoundSeal model BBC-13-2, or
equivalently rated material, may be built to
surround the jackhammer (on the top and 3 sides) and
the operator. A properly constructed enclosure,
using curtain material with a Sound Transmission
Class rating of STC 30 or greater, generally
provides a 5 dBA insertion loss. Such barrier shall
meet OSHA standards for worker exposure to
particulate matter.
iii. Portable noise shields made of steel frames
wrapped with noise curtain material, such as
SoundSeal model BBC-13-2, or equivalently
rated material, shall be used to form a noise
barrier in the direction of sensitive receptors and
completely block the line of sight between the
receptors and vac-truck. Noise curtains are
typically made out of a 1/4-inch thick heavy vinyl
material, often with a noise absorptive quilt
attached to one side. These noise curtains generally
weigh 1.5 lbs/sq.ft., have an STC rating of about
32, and come in 4-foot wide sheets complete with
grommets and Velcro edges to aid in hanging the
curtains and sealing the sheets side-by-side.
iii. A noise shroud enclosure shall be wrapped
around the head (i.e. chisel) of the hoe ram
whenever working within 200 feet of a receptor.
Shrouds may be selected from various manufacturers
such as Krupp Industries, Allied Hi-Ram, Montabert,
or Rammer Inc. with steel shrouds to attach to the
hoe ram head. Alternatively, a shroud may be
fabricated on-site by wrapping the chisel head with
a heavy vinyl noise curtain material, such as
SoundSeal BBC-13-2, or equivalently rated material,
and securing it with a tie wire.
iii. Noise curtain material, such as SoundSeal
model BBC-13-2, or equivalently rated material,
shall be used to form a noise barrier in the
direction of sensitive receptors and completely
block the line of sight between the receptors and
dump truck. It shall also be draped over the dump
truck to augment the engine housing and exhaust
stack. Noise curtains are typically made out of a
1/4-inch thick heavy vinyl material, often with a
noise absorptive quilt attached to one side. These
noise curtains generally weigh 1.5 lbs/sq.ft., have
an STC rating of about 32, and come in 4-foot wide
sheets complete with grommets and Velcro edges to
aid in hanging the curtains and sealing the sheets
side-by-side.
iii. Noise curtain material, such as SoundSeal
model BBC-13-2, or equivalently rated material,
shall be used to form a noise barrier in the
direction of sensitive receptors and completely
block the line of sight between the receptors and
auger drill rig. Noise curtains are typically made
out of a 1/4-inch thick heavy vinyl material, often
with a noise absorptive quilt attached to one side.
These noise curtains generally weigh 1.5 lbs/sq.ft.,
have an STC rating of about 32, and come in 4-foot
wide sheets complete with grommets and Velcro edges
to aid in hanging the curtains and sealing the
sheets side-by-side.
iii. Portable noise enclosures made of steel frames
wrapped with noise curtain material, such as
SoundSeal model BBC-13-2, or equivalently rated
material, shall be built to surround (top and 3
sides) the concrete saw and the operator. A well
made enclosure, using curtain material with a Sound
Transmission Class rating of STC 30 or greater, can
generally provide a 5 dBA insertion loss providing
there are no gaps in the enclosure. Noise tents may
be reused at other sites with proper care and
maintenance.
Sections 28-106
O.
Perimeter noise barriers shall be used as set
forth in sec. 28-101(g) of this chapter.
All gaps and spaces in the semi-permanent or
temporary barriers shall be filled with noise
attenuation material, and such barriers shall be
placed as close as possible to the noise source to
promote greater noise attenuation.
c. Construction of temporary barrier. Noise
barriers shall be made of noise-resistant material
sufficient to achieve a Sound Transmission Class
(STC) rating of STC 30 or greater, based on
sound transmission loss data taken according to
ASTM Test Method E90. Such a barrier may provide
as much as a 10 dBA insertion loss, provided it is
positioned as close as possible to the noise source
or to the receptors. To be at all effective, the
barrier must be long and tall enough to completely
block the line-of-sight between the noise source and
the receptors. The gaps between adjacent panels must
be filled-in to avoid having noise penetrate
directly through the barrier.
d. Noise curtains. Noise curtain material may
be mounted or hung over perimeter chain link fences,
or draped over small noise sources, to form a
flexible nose barrier. The chain link fences can
also be attached to the top of jersey bases.
3. Alternative barriers may be utilized in
accordance with site-specific conditions. For
example, shipping container (Conex) boxes are likely
already available to the responsible party. For
example, where work site space permits, these
container boxes or truck trailers may be positioned
along the edge of the work site to form a
semi-permanent noise barrier. These containers are
typically 8 feet wide by 8 feet tall and can be
double-stacked to form a noise barrier 16 feet in
height. The gaps between and/or under container
boxes shall be filled-in to avoid having noise
flanck around or under the container boxes.
Sections 28-108
b. Where
construction projects are of shorter duration than
15 days and within the property line and do not
require a perimeter barriers and are within 75 feet
of a residential receptor, a temporary or portable
(i.e. unanchored) noise barrier shall be made in
accordance with this section.
c. Construction of temporary barrier. Noise
barriers shall be made of noise-resistant material
sufficient to achieve a Sound Transmission Class (STC)
rating of STC 30 or greater, based on sound
transmission loss data taken according to ASTM Test
Method E90. Such a barrier may provide as much as a
10 dBA insertion loss, provided it is positioned as
close as possible to the noise source or to the
receptors. To be at all effective, the barrier must
be long and tall enough to completely block the
line-of-sight between the noise source and the
receptors. The gaps between adjacent panels must be
filled-in to avoid having noise penetrate directly
through the barrier.
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