2.
Response
to
Comments
2.9
Individual
Responses
to
Comments
from
Organizations
Noise
monitoring
location
7
in
the
Draft
EIR
was
selected
as
the
closest
existing
receptor
to
the
southern
end
of
the
Project
Site
development
area.
It
was
selected
based
on
its
elevation
above
other
buildings
having
direct
line-of-sight
with
the
Project
Site
development
area,
which
is
interrupted
by
a
single
row
of
eucalyptus
trees
with
5
to
6
feet
of
separation
between
each
tree.
Caltrans
research
has
shown
that
for
a
vegetative
strip
to
have
a
noticeable
effect
on
noise
levels,
it
must
be
dense
and
wide.
A
stand
of
trees
must
be
at
least
100
feet
wide
and
dense
enough
to
completely
obstruct
a
visual
path
to
the
source
to
attenuate
traffic
noise
by
5
dBA
(Caltrans,
2013).
Because
the
noise
monitor
microphone
was
not
obstructed
by
these
intervening
trees,
it
would
be
expected
that
no
meaningful
reduction
in
noise
as
a
result
of
the
trees
would
be
realized.
Ambient
noise
was
monitored
at
eight
locations
all
of
which
are
within
the
City
of
Brisbane,
six
of
which
were
on
the
flatlands
and
two
of
which
were
at
elevations
of
75
and
225
feet
above
mean
sea
level,
respectively.
A
third
party
acoustical
consultant
was
retained
to
consider
the
acoustical
effects
of
Brisbane’s
topography
and
the
effects
it
may
have
on
the
analysis
of
noise
impacts
of
the
Draft
EIR.
The
following
information
was
provided
by
Rosen,
Goldberg,
Der
&
Lewitz,
Acoustical
Consultants
(see
Appendix
I-3):
There
is
a
perception
by
some
residents
that
sounds
are
louder
in
Brisbane
than
in
other
communities
because
they
are
amplified
due
to
the
topography
of
the
city.
In
particular,
there
is
reference
to
“amphitheater-
like
conditions.”
The
perception
of
sounds
being
louder
or
amplified
is
best
explained
by
the
effect
of
the
terrain
on
ambient
noise
and
sound
propagation
rather
than
amplification.
First,
the
shape
of
the
terrain
tends
to
act
as
a
noise
barrier
for
ground
based
noise
sources
in
all
directions
except
toward
the
mouth
of
the
valley
to
the
east.
For
example,
the
hillsides
around
Brisbane
act
as
noise
barriers,
blocking
noise
from
US
101
east
and
south
of
the
city.
This
tends
to
reduce
the
background
sound
level
and
make
other
sounds
more
noticeable.
Second,
the
slope
of
the
valley
means
that
homes,
like
seats
in
an
amphitheater,
have
a
“good
view”
of
noise
sources.
This
means
that
noise
will
propagate
better
than
in
a
typical
flat
community
because
buildings
are
less
likely
to
intercept
the
line-of-sight
to
a
noise
source.
However,
the
noise
predictions
in
the
Draft
EIR
do
not
take
into
account
any
acoustical
shielding,
and
therefore,
are
appropriate
for
the
analysis
(Rosen
et
al.,
2014).
Noise
monitoring
locations
at
off-site
receptors
in
the
Draft
EIR
were
selected
based
on
proximity
to
the
Baylands
Project
Site
in
order
to
establish
the
existing
noise
levels
at
the
closest
sensitive
receptors
that
would
be
most
impacted
by
Brisbane
Baylands
Final
EIR
2.9.2-112
May
2015