Responses
to
OMB's
Comments
on
the
Headworks
Rule
Preamble
and
Regulatory
Text
Comments:

Preamble
Comment
1:
The
preamble
(
page
25)
states
that
the
Agency
would
like
to
provide
flexibility
with
respect
to
reduced
sampling
frequency
once
compliance
with
the
thresholds
was
established,
but
cannot
do
so
until
it
proposes
such
an
option.
Why
can't
the
agency
provide
such
flexibility
in
this
final
rule?
The
proposed
and
final
regulatory
text
does
not
seem
to
preclude
such
an
option
if
it
is
included
in
the
sampling
and
analysis
plan.
If
the
agency
believes
it
cannot
finalize
such
an
option
at
this
time,
but
supports
such
an
option,
then
the
agency
should
commit
to
a
proposed
rule
on
this
matter,
and
should
make
such
a
commitment
in
the
preamble
of
this
final
rule.

Response:
EPA
supports
the
concept
of
reducing
sampling
frequency
for
a
facility
once
compliance
has
been
established.
However,
we
believe
that
proper
implementation
of
the
approach
would
require
detailed
criteria
to
allow
overseeing
agencies
to
determine
if
a
facility
should
qualify
for
a
reduction
in
sampling
frequency
as
well
as
detailed
implementation
procedures
that
are
to
be
followed
by
the
facilities.
Because
the
Agency
did
not
include
a
discussion
of
these
detailed
criteria
and
procedures
in
the
proposed
rule
or
seek
public
comment
on
them,
we
believe
including
them
in
the
final
rule
might
make
the
rule
vulnerable
to
a
legal
challenge
under
the
Administrative
Procedure
Act.

Due
to
the
unavailability
of
resources
at
this
time,
EPA
cannot
commit
to
a
proposed
rule
to
address
this
option.

Preamble
Comment
2:
Please
explain
again
the
need
to
include
the
word
"
inadvertent"
in
the
regulatory
text.
It
is
not
clear
to
me
that
the
word
"
inadvertent"
signals
minor
losses.
One
can
inadvertently
do
something
that
will
result
in
a
major
release.

Response:
The
word
"
inadvertent"
is
not
intended
to
indicate
the
size
of
the
loss
but
rather
to
reinforce
that
such
a
loss
must
not
be
intentional,
be
a
result
of
neglect
or
carelessness
during
a
normal
operating
procedure
or
result
from
the
mismanagement
of
a
facility.
Due
to
the
exemption
being
expanded
to
include
the
F­
and
K­
listed
wastes,
with
which
there
is
no
economical
incentive
to
minimize
the
loss
of,
EPA
believes
that
it
is
essential
that
there
is
a
clear
understanding
as
to
when
a
loss
of
a
listed
hazardous
waste
into
wastewaters
can
be
deemed
as
a
de
minimis
release.
Risk
Assessment
Comments:

RA
Question
1:
When
do
the
risks
of
concern
arise?

Response:
We
used
the
chemical­
specific
dilution
attenuation
factors
(
DAFs)
in
ground
water
generated
for
the
Industrial
D
Waste
Management
Guidance
as
a
surrogate
for
a
chemical's
fate
and
transport
to
a
receptor
well
in
groundwater.
The
DAFs
reflect
the
extensive
modeling
done
for
the
development
of
the
Industrial
D
Waste
Management
Guidance.
The
DAFs
for
the
Guidance
were
calculated
using
the
EPACMTP
and
correspond
to
the
90th
percentile
values.

The
time
to
the
peak
concentration
was
not
reported
in
the
Guidance.
Therefore,
to
answer
your
question,
we
made
deterministic
model
runs
using
the
EPACMTP
(
the
same
model
used
for
the
Industrial
D
Waste
Management
Guidance).
We
used
the
median
values
for
the
model
input
parameters
and
assumed
the
landfill
was
unlined.
The
distance
to
the
receptor
well
and
the
well
location
in
the
plume
were
kept
the
same
as
in
the
Industrial
Waste
Guidance
Scenario.
The
travel
times
for
benzene
and
2­
ethoxyethanol
came
out
to
be
the
same
(
260
years)
and
the
time
to
peak
for
1,1,2­
trichloroethane
is
expected
to
be
similar
because
the
relevant
properties
are
similar.

RA
Question
2:
Did
EPA
consider
all
of
the
possible
"
scenarios"?
For
example,
in
Table
3­
5,
there
is
no
scenario
with
all
the
parameters
set
at
the
high­
end
(
HE).

Response:
We
divided
the
model
input
parameters
for
the
model
runs
into
four
groups:
(
1)
source
characteristics;
(
2)
fate
and
transport;
(
3)
exposure;
and
(
4)
toxicity.
The
source
component
encompasses
a
much
larger
number
of
input
variables
than
the
other
components.
Because
of
the
relationship
among
critical
variables,
and
because
the
model
is
not
sensitive
to
all
parameters
that
describe
the
source
component,
the
scenarios
were
designed
in
terms
of
combinations
of
variables
that
were
consistent
with
scientific
and
engineering
principles.
Thus,
with
any
scenario
for
which
a
source
was
set
to
high
end,
we
defined
two
to
four
sub­
scenarios
reflecting
high­
end
source
characterizations
using
combinations
of
the
critical
source
variables
set
to
high­
end
and
central
tendency
values.
For
this
analysis,
the
variables
for
the
nonaerated
treatment
train
and
for
the
aerated
treatment
train
are
described
in
Appendix
A
and
Appendix
A­
2
of
the
Risk
Assessment
Background
Document,
and
they
provide
the
values
used
for
each
scenario.
Tables
3­
2,
3­
3,
and
3­
4
of
the
Risk
Assessment
Background
Document
provide
the
results
for
these
analyses
for
the
three
chemical
constituents
of
concern:
benzene,
2­
ethoxyethanol,
and
1,1,2­
trichloroethane,
respectively.

It
is
EPA's
policy
for
high­
end
analyses
that
only
two
parameters
are
set
at
the
high­
end
and
the
remaining
parameters
set
at
central
tendency
values.
This
selection
of
parameters
yields
results
at
90th
or
higher
percentiles.
For
central
tendency
results,
all
parameters
are
set
to
central
tendency.
We
did
not
consider
any
high­
end
scenario
with
all
parameters
set
to
high­
end
because
that
will
lead
to
very
high
percentile
values,
i.
e.,
approaching
the
99th
percentile
or
higher.
RA
Question
3:
Is
the
choice
of
parameter
settings
explained
in
this
comment?

Response:
As
explained
above,
the
source
component
encompasses
a
much
larger
number
of
input
variables
than
the
other
components.
Because
of
the
relationship
among
critical
variables,
and
because
the
model
is
not
sensitive
to
all
parameters
that
describe
the
source
component,
the
scenarios
were
designed
in
terms
of
combinations
of
variables
that
were
consistent
with
engineering
principles.
Thus,
within
any
scenario
for
which
the
source
was
set
to
high­
end,
EPA
defined
two
to
four
sub­
scenarios
reflecting
high­
end
source
characterization
using
combinations
of
the
critical
source
variables
set
to
high­
end
and
central­
tendency
values.
For
this
analysis,
the
variables
that
were
varied
for
the
nonaerated
treatment
train
and
the
aerated
treatment
train
are
described
in
Appendix
A
of
the
Risk
Background
Document.
Appendix
A
also
provides
the
numerical
values
used
for
the
various
input
source
parameter
settings.
Economics
Comments:

Economics
Comment
1:
Add
narrative
to
describe,
step­
by­
step,
the
methodology
used
to
derive
the
estimates
of
cost
savings.
Include
in
this
description
about
what
is
being
analyzed,
assumptions,
and
alternatives
considered.
Include
a
description
of
the
sensitivity
analysis,
and
acknowledge
that
states
do
not
have
to
adopt
the
final
rule.

Response:
New
narrative
methodology
sections
were
added
to
the
"
Economics
Background
Document"
(
EBD),
which
is
now
dated
15
July
2005
with
239
pages.
One
new
methodology
section
added
to
the
EBD
is
an
"
Overview
of
Methodology"
(
Section
II.
C,
pages
11
to
18)
which
contains
explanations
of
the
overall
macro
assumptions
concerning
(
a)
100%
state
adoption
of
the
final
rule
with
acknowledgment
that
states
are
not
required
and
that
all
states
may
not
adopt
the
rule,
(
b)
100%
facility
compliance
with
the
final
rule
conditions,
(
c)
vintage
years
of
the
19
databases
applied
in
the
analysis,
(
d)
treatment
of
SQGs
in
the
analysis,
(
e)
the
discount
rate
applied,
and
(
f)
sources
and
treatment
of
uncertainty
in
the
analysis.

A
second
new
methodology
section
added
to
the
EBD
is
a
"
Step­
by­
Step
Methodology"
(
Section
II.
D,
pages
19
to
40)
which
provides
new
narrative
descriptions
and
a
re­
formatted/
re­
organized
presentation
of
micro
assumptions,
key
factors,
computation
spreadsheets,
and
supplemental
data
tables.

A
third
new
methodology
section
was
created,
"
Ancillary
Impact
Methodologies"
(
Section
II.
E,
pages
41­
46),
which
contains
enhanced
(
re­
organized)
narrative
and
tabular
presentations
of
(
a)
state
waste
fee
revenue
impacts,
(
b)
waste
transport/
manifest
impacts,
and
(
c)
sensitivity
analysis
concerning
sensitivity
of
average
annual
cost
savings,
to
projected
future
annual
growth
in
affected
waste
quantities.

Although
not
specifically
requested
by
OMB,
the
context
of
the
new
methodology
sections
was
enhanced
in
the
EBD
by
adding
two
additional
new
narrative
sections
which
(
a)
describe
the
"
Regulatory
Need"
for
this
final
rule
(
Section
II.
A,
page
7),
and
(
b)
summarizes
the
2003
headworks
proposed
rule
public
comments
related
to
economics
topics
(
Section
II.
B,
pages
9
to
11).

Economics
Comment
2:
Please
explain
why
the
addition
of
direct
monitoring
option
saves
money
if
it
is
more
expensive
than
the
existing
mass
balance
requirement.

Response:
The
revised
EBD
(
pages
36­
37)
provides
the
following
new
narrative
explanation
of
why
direct
monitoring
is
expected
to
provide
cost
savings:

"
The
1999
petitioner
requesting
this
final
rule
(
Chemical
Manufacturers
Association),
and
many
of
the
25
public
commentors
on
OSW's
08
April
2003
headworks
proposed
rule,
prefer
adoption
of
"
direct
monitoring"
rather
than
the
mass
balance
method.
However,
it
appears
that
direct
monitoring
may
involve
higher
cost
at
$
4,680/
year
average
cost
per
facility,
compared
to
an
estimated
$
1,444/
year
average
cost
per
facility
for
the
mass
balance
method.
OSW
estimated
average
annual
costs
per
facility
for
these
two
methods,
by
applying
the
following
data
sources
and
computations:

°
Direct
Monitoring:
$
97.50
average
cost
per
analytic
event
from
OSW's
Sept
2000
"
Unit
Cost
Compendium",
Appendix
N;
laboratory
analysis
using
USEPA
analytic
method
8260/
8021
(
GC/
MS)
for
volatile
organic
chemicals
[($
97.50
per
direct
monitoring
event)
x
(
1
monitoring
event
per
week)
x
(
48
operating
weeks/
year)
=
$
4,680/
year]

°
Mass
balance:
$
1,444/
year
average
cost
per
facility
from
USEPA­
OSW
ICR
Nr.
1189:
Identification,
Listing,
and
Rulemaking
Petitions.

Note
that
the
existing
USEPA
Clean
Water
Act
(
CWA)
industrial
wastewater
monitoring
requirements
are
mostly
for
"
effluent"
wastewaters
(
i.
e.,
output
side
of
wastewater
treatment
systems)
rather
than
for
"
influent"
headworks
wastewaters
(
i.
e.,
input
side
of
wastewater
treatment
systems).
Consequently,
direct
monitoring
costs
are
assumed
in
the
headworks
economic
analysis
to
be
incremental
to
baseline
for
compliance
with
the
RCRA
headworks
exemption,
rather
than
involve
existing
equipment
and
personnel
at
no
additional
cost.
However,
in
spite
of
this
apparent
unfavorable
cost,
the
1999
petitioner
for
this
final
rule,
as
well
as
a
number
of
public
commentors
on
the
HWIR
final
rule,
provided
the
following
rationales
why
direct
monitoring
is
preferable
(
i.
e.,
net
beneficial)
compared
to
the
mass
balance
method:

°
Provides
flexibility
°
Yields
reliable,
accurate,
statistically
defensible
data
°
Facilitates
documentation
of
compliance
°
Is
straightforward
(
mass
balance
deters
use
of
the
headworks
exclusion
because
it
is
not
as
precise)
°
Allows
facilities
to
apply
the
exclusion
to
its
full
intended
regulatory
limit
Consequently,
because
direct
monitoring
is
more
accurate
and
is
not
a
worst­
case
assumption
like
mass
balance
(
i.
e.,
mass
balance
calculations
are
formulated
on
solvent
use
rather
than
on
spent
solvent
discharges),
more
facilities
will
now
be
able
to
use
the
exemption
and
will
no
longer
have
the
cost
of
managing
their
wastewater
treatment
sludges
as
hazardous.
Table
12
[
of
the
EBD]
provides
the
assumptions
and
computations
of
the
potential
number
of
F001
to
F005
spent
solvent
generating
facilities
which
are
not
currently
claiming
the
headworks
exemption
(
excluding
the
facilities
already
counted
in
Revision
#
1
impacts),
which
may
be
induced
into
claiming
the
exemption
because
of
direct
monitoring,
thereby
generating
net
cost
savings
from
avoided
Subtitle
C
management
costs
for
wastewater
sludges.
