2.
Response
to
Comments
2.9
Individual
Responses
to
Comments
from
Organizations
duration
is
beneficial,
yet
the
same
drug
is
toxic
if
the
dose
exceeds
that
which
is
recommended.
Deleterious
impacts
to
human
health
from
exposure
to
constituents
detected
in
onsite
media
are
evaluated
as
carcinogenic
and
non-
carcinogenic.
Exposure
pathways
are
determined
by
the
nature
of
the
constituent.
For
example,
volatile
organic
compounds
volatilize,
therefore
the
exposure
pathway
by
which
these
constituents
should
be
evaluated
is
inhalation,
as
this
is
the
most
conservative
pathway.
Specific
risks
for
illness
related
to
hazardous
constituents
on
the
project
site
will
be
calculated
by
the
regulatory
agencies
during
the
human
health
risk
assessment
and
the
process
of
setting
risk-
based
cleanup
goals
and
remediation
requirements.
See
for
discussion
of
risk-based
remediation
standards.
Groundwater
underlying
was
investigated
in
2010
(Appendix
C,
BFK
2011).
Thirty-nine
monitoring
wells
and
piezometers
were
placed
in
in
2010,
which
Harding
Lawson
determined
to
be
a
sufficient
number
to
detect
contamination
in
area
groundwater
as
part
of
their
study
given
the
size
of
the
area
being
tested
and
their
research
design.
Groundwater
samples
collected
from
the
shallow
and
deep
groundwater
and
submitted
for
analysis
of
total
petroleum
hydrocarbons
(TPH)
(C6-C10)
–
gasoline
range,
TPH
(C10-C28)
–
diesel
range,
TPH
(C28-C40)
–
motor
oil
range,
volatile
organic
compounds
(VOCs)
and
total
threshold
limit
concentration
(TTLC)
metals
indicate
that
methyl
tertiary
butyl
ether
(MTBE)
was
detected
in
one
sample
at
a
low
concentration,
all
other
VOCs
were
not
detected
in
concentrations
greater
than
their
respective
reporting
limits,
i.e.,
were
not
detected
(ND).
TPH
(C6-C10)
–
gasoline
range
was
ND.
TPH
(C10-C28)
–
diesel
range
was
detected
in
six
groundwater
samples
at
low
concentrations.
TPH
(C28-C40)
–
motor
oil
range
was
detected
in
the
same
six
groundwater
samples
also
at
low
concentrations.
Groundwater
underlying
is
being
monitored
per
the
RWQCB.
Vertical
drilling
is
the
standard
of
practice
for
VOC
testing.
See
13
for
discussion
of
the
remediation
review
and
approval
process.
As
discussed
in
Title
27
closure
of
the
former
Brisbane
Landfill
must
address
the
presence
of
leachate
and
the
requirement
to
prevent
any
increases
in
leachate
that
exceed
any
regulatory
thresholds,
as
well
as
the
requirement
for
control
of
landfill
gas.
Groundwater
gradient
has
been
measured
consistently
since
1982,
and
has
been
found
to
be
variable
depending
upon
its
onsite
location.
The
direction
of
groundwater
gradient
is
reported
as
radial
outward
from
the
center
of
the
northern
tank
farm,
north-northeast
toward
the
tree-lined
channel
in
the
northern
portion
of
the
site,
westward
along
the
eastern
portion
of
the
site
and
southeast
along
the
south
and
southeastern
portion
of
the
site.
Brisbane
Baylands
Final
EIR
2.9.1-30
May
2015