Document ID: EPA-HQ-OAR-2003-0048-0184
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2004-03-03T05:00Z

125
enclosure
and
incineration­
based
control
or
biofilter,

regardless
of
whether
or
not
batch
and
continuous
presses
are
treated
as
separate
equipment
groups.
In
addition,

there
is
a
Method
204
certified
PTE
around
a
181­
ft
continuous
press
at
a
newer
PCWP
facility
(
which
was
not
included
in
original
data
collection
efforts
and
the
preproposal
MACT
floor
determination);
however,
this
press
has
had
some
operational
problems
associated
with
its
PTE.
It
is
not
clear
if
the
operational
problems
experienced
by
this
181­
ft­
long
press
are
the
result
of
poor
PTE
design
or
inherent
technical
difficulties
associated
with
enclosing
long
continuous
PCWP
presses.

Long
continuous
presses
are
generally
being
installed
at
new
PCWP
facilities,
as
opposed
to
being
retrofit
at
existing
facilities.
Given
that
there
is
at
least
one
long
continuous
press
(
110
ft)
with
a
Method
204
certified
PTE
that
has
not
experienced
operational
problems
with
its
press
enclosure,
we
feel
that
wood
products
enclosures
(
as
defined
in
today's
final
rule)
can
be
designed
around
long
continuous
presses.
We
recognize
that
higher
cost
may
be
associated
with
wood
products
enclosures
around
long
continuous
presses
than
for
batch
presses,
but
the
CAA
does
not
allow
us
to
consider
cost
at
the
MACT
floor
control
level.

We
note
that
enclosures
greater
then
200
ft
in
length
126
are
common
in
the
printing/
publishing
industry.
However,
we
do
recognize
there
are
differences
in
the
enclosures
used
in
the
printing/
publishing
industry
and
those
in
the
PCWP
industry.
Although
not
cyclical
in
operation
like
batch
presses,
continuous
presses
are
heated
operations
and
may
also
have
internal
pressurization
issues
similar
to
those
raised
by
the
commenters
for
batch
presses.
Therefore,
we
feel
it
is
appropriate
for
the
same
definition
of
wood
products
enclosure
promulgated
for
batch
presses
to
apply
to
long
continuous
presses
as
well
(
as
opposed
to
Method
204
certification).

3.
MACT
Floor
Determinations
of
No
Emissions
Reductions
Comment:
Industry
commenters
stated
that
thesupported
our
proposed
MACT
floor
determinations
of
no
emissions
reductions
for
some
process
units
are
correct
and
accurately
reflect
current
PCWP
facility
practices.
The
commenters
stated
that
the
method
used
to
determine
the
MACT
floors
was
proper
under
the
CAA
and,
arguing
our
approach
was
fully
consistent
with
recent
decisions
made
byapplicable
case
law
in
the
U.
S.
Court
of
Appeals
for
the
D.
C.
Circuit
(
i.
e.,

Cement
Kiln
Recycling
Coalition
v.
EPA,
255
F.
3d
855
(
D.
C.

Circuit
2001)
and
National
Lime
Association
v.
EPA,
233
F.
3d
625
(
D.
C.
Cir.
2000)).
According
to
the
industry
commenters,
in
Cement
Kiln,
EPA
identified
the
median
of
the
best­
performing
12
percent
of
sources
and
set
the
MACT
floor
127
at
the
worst
emission
level
achieved
by
any
source
using
the
same
emission
control
technology
that
was
used
by
most
of
the
top
12
percent.
The
industry
commenters
noted
that
the
D.
C.
Circuit
ruled
that
this
MACT
floor
was
not
a
valid
estimate
of
the
performance
of
the
best­
performing
sources
in
practice
and
that
EPA
assumed
that
control
technology
was
the
only
way
to
reduce
HAP
emissions,
but
other
factors
were
influencing
the
reduction.
The
industry
commenters
noted
that
some
of
those
factors
could
have
been
inadequate
maintenance
or
inferior
operating
practices,
in
which
case
the
worst­
performing
sources
would
certainly
not
be
an
estimate
of
the
best­
performing
sources
under
the
most
adverse
conditions.
According
to
the
industry
commenters,

the
court
noted
that
if
EPA
could
demonstrate
that
MACT
technology
significantly
controlled
emissions,
or
that
factors
other
than
the
control
had
a
negligible
effect,
the
MACT
approach
could
be
a
reasonable
means
of
satisfying
the
statute's
requirements.
The
industry
commenters
noted
that,

in
developing
the
PCWP
rule,
EPA
again
followed
the
MACT
approach,
determining.
EPA
properly
determined
that
the
average
of
the
best­
performing
12
percent
of
certain
existing
PCWP
process
units
did
not
reflect
the
use
of
any
control
technology.
The
industry
commenters
further
noted
that,
in
the
proposed
PCWP
rule,
EPA
determinedand
that
no
other
universally
applicable
variables
would
affect
HAP
128
emissions,
a
determination
it
did
not
make
in
Cement
Kiln.

According
to
the
industry
commenters,
for
the
PCWP
process
units
for
which
the
MACT
floor
is
90
percent,
EPA
again
determined
that
there
are
no
other
factors
that
significantly
impact
the
removal
efficiencies
of
the
add­
on
controls.
For
these
reasons,
the
industry
commenters
contended
that
EPA
corrected
the
mistakes
made
in
the
Cement
Kiln
situation
when
developing
the
PCWP
MACT.

The
industry
commenters
noted
that
in
National
Lime,
EPA
followed
a
similar
MACT
approach
to
Cement
Kiln,
but
it
had
insufficient
data
for
some
HAP.
According
to
the
commenters,
if
EPA
found
an
insufficient
number
of
plants
in
its
database
controlling
a
particular
HAP
with
pollution
control
technology,
it
determined
that
the
emission
floor
was
no
control.
The
industry
commenters
noted
that
the
D.
C.

Circuit
stated
that
if
EPA
did
not
consider
alternative
pollution­
reducing
measures,
it
could
not
decline
to
set
emissions
standards
on
the
grounds
that
the
best­
performing
sources
did
not
use
control
technology.
The
industry
commenters
stated
that
the
D.
C.
Circuit
ruling
in
National
Lime
does
not
prevent
EPA
from
setting
a
MACT
floor
of
no
emissions
reductions;
however,
it
does
require
EPA
to
examine
all
methods
of
removing
HAP
before
setting
a
floor.

According
to
the
industry
commenters,
in
developing
the
PCWP
rule,
EPA
did
look.
The
commenters
also
claimed
that
EPA
129
looked
at
pollution
prevention
(
P2)
measures
and
other
approaches
to
determining
the
MACT
floor
but,
found
none
that
are
universally
applicable
to
reduce
HAP
emissions.

Therefore,
the
industry
commenters
contended
that
EPA
is
permitted
by
statute
to
set
the
MACT
floor
for
existing
sources
at
any
level
not
less
stringent
than
the
average
limitation
achieved
by
the
best­
performing
12
percent,
even
if
that
floor
level
reflects
no
reduction
in
emissions.

One
commenter
disagreed
with
the
industry
commenters
and
stated
that
not
establishing
emission
reduction
limits
for
operations
like
miscellaneous
coating
and
wastewater
is
unlawful.
The
commenter
argued
that
EPA
should
not
make
its
MACT
floor
decisions
based
on
insufficient
information
and
the
fact
that
there
is
no
current
control
in
place.
The
commenter
stated
that,
according
to
National
Lime
Ass'n
v.

EPA,
233
F.
3d
625,
633­
634
(
D.
C.
Cir.
2000),
EPA
cannot
set
a
MACT
floor
of,
and
therefore
was
permitted
to
base
a
no
emissions
reductions
because
it
feels
that
a
pollutant
is
not
controlled
by
any
particular
technology.
The
commenter
also
stated
that
EPA
failed
to
explain
why
insufficient
data
are
available
and
what
additional
steps
could
be
taken
to
obtain
the
necessary
data.
For
these
reasons,
the
commenter
stated
that
EPA's
proposed
MACT
floor
levels
of
no
emissions
reductions
are
unlawfulreduction
floor
on
the
PCWP
record.

Response:
As
explained
in
the
proposal
preamble
and
130
supporting
documentation,
for
those
process
units
not
required
to
meet
the
control
requirements
in
the
PCWP
rule
as
proposed,
we
determined
that:
(
1)
the
MACT
floor
level
of
control
is
no
emissions
reductions,
and
beyond­
the­
floor
control
options
are
too
costly
to
be
feasible;
or
(
2)

insufficient
information
is
available
to
conclude
that
the
MACT
floor
level
of
control
is
represented
by
any
emissions
reductions.
We
based
our
MACT
floor
determinations
for
PCWP
emission
sources
on
the
presence
or
absence
of
an
add­
on
air
pollution
control
device
because
we
are
not
aware
of
any
demonstrated
P2
techniques
that
can
be
universally
applied
across
the
industry,
and
we
have
no
information
on
the
degree
of
emissions
reduction
that
can
be
achieved
through
P2
measures.
Therefore,
to
our
knowledge
the
use
of
add­
on
controls
is
the
only
way
in
which
PCWP
sources
can
currently
limit
HAP
emissions,
and
the
only
way
to
identify
the
MACT
floor
for
these
sources
is
to
identify
a
level
that
corresponds
to
that
achieved
by
the
use
of
add­
on
controls.

When
determining
the
MACT
floor,
we
ranked
the
process
units
by
control
device
rather
than
by
actual
unit­
specific
emissions
reductions
because
we
have
limited
inlet/
outlet
emissions
data.
Based
on
the
available
information,
we
are
not
aware
of
any
significant
design
or
operational
differences
among
each
type
of
control
system
evaluated
that
would
affect
the
ranking
of
process
units.
Furthermore,
we
131
are
not
aware
of
factors
other
than
the
type
of
control
system
used
that
would
significantly
affect
the
ranking
of
process
units.
An
analysis
of
the
available
emissions
data
does
not
reveal
any
process
variables
that
can
be
manipulated
(
without
altering
the
product)
to
achieve
a
quantifiable
reduction
in
emissions.
Ranking
process
units
according
to
control
device,
we
determined
that
the
MACT
floor
is
no
emissions
reductions
for
several
process
unit
groups
including
press
predryers,
fiberboard
mat
dryers,
and
board
coolers
at
existing
affected
sources;
and
dry
rotary
dryers,
veneer
redryers,
softwood
plywood
presses,
hardwood
plywood
presses,
engineered
wood
products
presses,
hardwood
veneer
dryers,
humidifiers,
atmospheric
refiners,
formers,

blenders,
rotary
agricultural
fiber
dryers,
agricultural
fiber
board
presses,
sanders,
saws,
fiber
washers,
chippers,

log
vats,
lumber
kilns,
storage
tanks,
wastewater
operations,
miscellaneous
coating
operations,
and
stand­
alone
digesters
at
new
and
existing
affected
sources.

As
explained
in
the
promulgation
BID
and
supporting
documentation,
we
also
determined
that
beyond­
the­
floor
control
options
are
too
costly
for
these
process
unit
groups.

At
proposal,
we
requested
comment
on
whether
no
emissions
reductions
for
miscellaneous
coating
operations
and
for
wastewater
operations
is
appropriate
(
68
FR
1276,
132
January
9,
2003).
We
also
requested
that
commenters
on
this
issue
submit
any
information
they
might
have
on
HAP
or
VOC
emissions
from
miscellaneous
coating
operations
and
wastewater
operations.
However,
no
additional
information
on
these
operations
was
received
from
any
of
the
commenters
on
the
proposed
rule.
Following
proposal,
we
reviewed
our
MACT
analyses
for
miscellaneous
coating
and
wastewater
operations,
as
described
in
the
following
paragraphs
and
in
the
promulgation
BID
and
supporting
documentation.
For
miscellaneous
coating
operations,
we
gathered
some
additional
information
and
were
able
to
revise
our
conclusions
regarding
MACT
in
the
absence
of
specific
information
on
the
emissions
reduction
achieved.
However,

we
have
no
more
reason
to
feel
now
than
we
did
at
proposal
that
PCWP
wastewater
operations
are
in
fact
subject
to
any
emission
control
measures.

Based
on
the
available
information,
we
have
no
basis
to
conclude
that
the
MACT
floor
for
new
or
existing
sources
is
represented
by
any
emission
reductions
for
several
of
miscellaneous
coating
processes
(
i.
e.,
anti­
skid
coatings,

primers,
wood
patches
applied
to
plywood,
concrete
forming
oil,
veneer
composing,
and
fire
retardants
applied
during
forming),
and
we
determined
that
there
are
no
cost­
effective
beyond­
the­
floor
measures
to
reduce
HAP
from
these
coating
processes.
However,
some
facilities
reported
use
of
133
water­
based
(
non­
HAP)
coatings
in
their
MACT
survey
responses
for
other
types
of
coatings
(
including
edge
seals,

nail
lines,
logo
paint,
shelving
edge
fillers,
and
trademark/
gradestamp
inks).
Other
facilities
reported
use
of
solvent­
based
coatings
for
these
processes.
In
some
instances,
a
few
respondents
provided
information
on
the
percent
HAP
content
of
a
solvent­
based
coating.

Solvent­
based
coatings
do
not
always
contain
HAP
(
e.
g.,
the
solvent
may
be
mineral
oil
which
does
not
contain
HAP),
and
water­
based
coatings
typically
do
not
contain
HAP.
Thus,

many
of
the
coatings
reported
in
the
MACT
survey
responses
are
non­
HAP
coatings.
While
the
emission
reduction
achieved
as
a
result
of
coating
substitutions
cannot
be
determined,

it
is
clear
that
use
of
non­
HAP
coatings
represents
the
MACT
floor
because
of
the
large
number
of
facilities
reporting
use
of
non­
HAP
coatings.
Beyond­
the­
floor
options
were
not
considered
for
edge
seals,
nail
lines,
logo
paint,
shelving
edge
fillers,
and
trademark/
gradestamp
inks
because
no
further
emissions
reductions
can
be
achieved
than
through
use
of
non­
HAP
coatings.
Based
upon
our
revised
MACT
analysis,
the
final
PCWP
rule
requires
use
of
non­
HAP
coating
for
processes
identified
as
group
1
miscellaneous
coating
processes.

The
definition
of
non­
HAP
coating
included
in
the
final
rule
was
based
on
the
description
of
non­
HAP
coatings
in
the
134
final
WBP
NESHAP
(
subpart
QQQQ
to
40
CFR
part
63).
This
definition
allows
for
unavoidable
trace
amounts
of
HAP
that
may
be
contained
in
the
raw
materials
used
to
produce
certain
coatings.
Through
the
definition
of
group
1
miscellaneous
coatings
in
the
final
rule,
kiln­
dried
lumber
is
excluded
from
the
requirement
to
use
non­
HAP
coatings
because
application
of
coatings
used
at
kiln­
dried
lumber
manufacturing
facilities
is
not
part
of
the
PCWP
source
category.
Although
trademarks/
gradestamps
are
applied
to
kiln­
dried
lumber,
lumber
kilns
are
the
only
processes
at
kiln­
dried
lumber
manufacturing
facilities
covered
under
the
PCWP
source
category.

For
wastewater
operations,
we
concluded
that
we
had
insufficient
information
to
conclude
that
the
MACT
floor
level
of
control
is
represented
by
any
emissions
reductions.

The
available
information
on
wastewater
operations
collected
as
part
of
the
MACT
survey
of
the
PCWP
industry
and
information
contained
in
State
permits
indicated
that
these
sources
of
emissions
were
not
the
subject
of
control
requirements
and
were
not
expected
to
be
significant
sources
of
HAP
or
VOC
emissions.
As
stated
above,
we
received
no
comments
containing
additional
information
on
emissions
reduction
measures
or
HAP/
VOC
emissions
from
wastewater
operations.
Thus,
we
have
no
more
reason
to
feel
now
than
we
did
at
proposal
that
PCWP
wastewater
operations
are
in
135
fact
subject
to
any
control
measures.
As
a
result,
since
no
information
shows
that
these
PCWP
operations
use
add­
on
controls,
there
is
no
identifiable
numerical
emissions
level
that
would
correspond
to
a
MACT
floor
level
reflecting
the
use
of
controls,
and
the
only
floor
level
demonstrable
based
on
current
data
is
no
emissions
reduction.
Furthermore,

given
that
our
best
data
show
that
the
emissions
from
wastewater
operations
are
less
than
1
ton/
yr,
we
concluded
that
application
of
the
control
measures
mentioned
above
would
not
be
cost
effective
beyond­
the­
floor
options.
In
response
to
the
commenter's
objection
to
the
incompleteness
of
the
data
set
for
these
PCWP
operations,
we
note
that
the
D.
C.
Circuit
does
not
require
EPA
to
obtain
complete
data
as
long
as
we
are
able
to
otherwise
estimate
the
MACT
floor
(
Sierra
Club
V.
EPA,
167
F.
3d
658,662
(
D.
C.
Cir.
1999)).

Unlike
dryers
and
presses
at
PCWP
plants,
wastewater
operations
have
not
been
subjected
by
permitting
authorities
to
controls
for
HAP
emissions.
We
expended
much
effort
in
the
early
stages
of
the
project
gathering
complete
and
accurate
information
on
the
PCWP
processes
with
the
most
potential
for
HAP
emissions
and
the
greatest
potential
for
emission
control
(
i.
e.,
the
processes
that
have
been
the
focus
of
permit
requirements
limiting
HAP/
VOC
emissions)
and
the
final
PCWP
rule
addresses
emissions
from
these
process
units.
136
Had
we
been
given
reason
to
feel
that
there
were
emissions
control
measures
associated
with
wastewater
operations,
we
would
have
gathered
more
information
for
these
processes
earlier
in
the
project.
Even
though
we
have
determined
that
the
current
MACT
floor
for
these
PCWP
operations
is
no
emission
reduction,
since
available
information
indicates
they
are
not
controlled,
the
HAP
emissions
from
wastewater
operations
(
and
other
PCWP
sources
with
MACT
determinations
reflecting
no
emissions
reductions)

will
be
considered
further
when
we
review
residual
risk
as
required
under
section
112(
f).

E.
New
Source
MACT
Comment:
One
commenter
objected
to
our
determination
that
MACT
is
the
same
degree
of
control
for
new
and
existing
sources
for
many
process
units
based
on
the
fact
that
the
best
technology
is
the
same
for
new
and
existing
sources
(
i.
e.,
incineration­
based
controls
or
biofilters).
The
commenter
pointed
out
that,
according
to
the
proposal
BID,

the
maximum
percent
control
efficiency
is
in
the
upper
90s
for
THC,
formaldehyde,
and
methanol.
The
commenter
noted
that
the
CAA
requires
the
MACT
floor
to
be
based
on
the
degree
of
emissions
reduction
achieved
in
practice
by
the
best­
controlled
similar
source.
Thus,
the
commenter
requested
that
we
revise
the
new
source
MACT
requirements
for
process
units
based
upon
the
greatest
reductions
137
recorded.

Response:
As
explained
in
the
preamble
to
the
proposed
rule
and
supporting
documentation,
the
MACT
floor
for
both
new
and
existing
sources
is
based
on
the
estimate
of
the
performance
achieved
through
application
of
RTO,
RCO,
or
biofilters.
We
acknowledge
that
some
incineration­
based
controls
and
biofilters
can
achieve
greater
than
90
percent
reduction
in
HAP
or
THC
during
a
single
performance
test
or
a
test
run
within
a
performance
test.
However,
we
also
recognize
that
the
percent
reduction
achieved
can
vary
according
to
pollutant
inlet
concentration,
a
factor
that
is
not
directly
controllable
from
a
process
or
control
device
standpoint.
Other
unknown
factors
may
also
cause
variability
in
control
system
performance.
For
example,
we
have
THC
percent
reduction
data
for
an
RTO
used
to
control
emissions
from
three
tube
dryers
and
a
press
at
an
MDF
plant
for
two
emission
tests
conducted
at
different
times.
In
1996,
the
RTO
achieved
92.7
percent
reduction
of
THC,
and
in
1998
the
same
RTO
achieved
98.9
percent
reduction
of
THC.

In
addition,
we
have
emissions
test
data
for
the
same
process
unit
and
control
system
for
multiple
years,
and
these
data
show
different
emission
factors,
indicating
that
variability
is
inherent
within
each
process
unit
and
control
system
combination.
Thus,
we
estimate
that
the
best
MACT
technology
achieves
90
percent
HAP
reductions
when
138
variations
in
operations
and
measurements
are
considered.

F.
Definition
of
Control
Device
Comment:
Several
commenters
requested
that
we
add
scrubbers
and
adsorbers
to
the
proposed
definition
of
"
control
device"
and
that
condensers
be
omitted
from
the
definition.
One
of
the
commenters
operates
a
particleboard
press
that
is
equipped
with
a
condenser
that
condenses
steam
from
the
press
exhaust
and
then
routes
the
condensate
to
an
onsite
wastewater
treatment
system.
The
remaining
noncondensed
gases
are
combusted
in
an
onsite
boiler
as
supplemental
fuel.
This
commenter
would
like
to
be
able
to
comply
with
the
PBCO
for
reconstituted
wood
products
presses
rather
than
demonstrate
compliance
with
one
of
the
add­
on
control
system
compliance
options
(
e.
g.,
90
percent
emissions
reduction)
or
emissions
averaging
provisions;

however,
the
commenter
noted
that
PBCO
only
apply
to
uncontrolled
emission
sources.
Therefore,
the
commenter
requested
that
the
definition
of
control
device
be
limited
only
to
those
add­
on
control
systems
that
were
designed
with
HAP
removal
as
the
primary
goal.

Response:
We
disagree
with
the
commenters
that
the
proposed
definition
of
control
device
should
be
changed.

The
definition
in
the
final
rule
does
not
include
scrubbers
or
absorbers
but
does
include
condensers
and
combustion
units
that
incinerate
process
unit
exhausts.
For
purposes
139
of
MACT
standards
development,
the
reason
a
control
device
is
installed
is
immaterial.
All
control
devices
or
techniques
that
reduce
HAP
emissions
are
considered
when
setting
MACT
standards.
We
note
that
the
PBCO
were
developed
and
included
in
the
PCWP
rule
for
inherently
lowemitting
process
units
or
process
units
with
P2
techniques
and
not
for
process
units
with
add­
on
control
systems.

Therefore,
the
particleboard
press
equipped
with
the
condenser
and
combustion
unit
described
by
the
commenter
cannot
comply
using
the
PBCO.

In
the
proposed
PCWP
rule,
we
intentionally
omitted
absorbers
(
e.
g.,
wet
scrubbers)
from
the
list
of
potential
control
devices
because
these
technologies
generally
are
not
reliable
for
reducing
HAP
emissions.
These
wet
systems
may
achieve
short­
term
reductions
in
THC
or
gaseous
HAP
emissions;
however,
the
HAP
and
THC
control
efficiency
data,

which
range
from
slightly
positive
to
negative
values,

indicate
that
the
ability
of
these
wet
systems
to
absorb
water­
soluble
compounds
(
such
as
formaldehyde)
diminishes
as
the
recirculating
scrubbing
liquid
becomes
saturated
with
these
compounds.
We
wished
to
limit
the
examples
included
in
the
definition
of
control
device
to
those
devices
for
which
we
have
data
to
demonstrate
that
they
are
effective
in
reducing
HAP
emissions
from
PCWP
facilities.
However,
we
note
that
the
definition
includes
the
phrase
"
but
not
140
limited
to"
and
does
not
exclude
other
types
of
controls.

We
are
aware
that
new
technologies
(
some
of
which
may
be
adsorption­
based
or
absorption­
based)
may
be
developed
that
effectively
reduce
HAP
emissions
from
PCWP
sources.
The
definition
of
control
device
does
not
prevent
their
development
or
use.

Facilities
using
wet
scrubbers
or
WESP
to
meet
the
addon
APCD
or
emissions
averaging
compliance
options
can
petition
the
Administrator
for
approval
of
site­
specific
operating
requirements
to
be
used
in
demonstrating
continuous
compliance.
Alternatively,
facilities
using
a
wet
scrubber
or
WESP
may
use
a
THC
CEMS
to
show
that
the
THC
concentration
in
the
APCD
exhaust
remains
below
the
minimum
concentration
established
during
the
performance
test.
In
addition,
facilities
using
wet
control
devices
(
e.
g.,
wet
scrubber
or
WESP)
as
the
sole
means
of
reducing
HAP
emissions
must
submit
with
their
Notification
of
Compliance
Status
a
plan
for
review
and
approval
to
address
how
organic
HAP
captured
in
the
wastewater
from
the
wet
control
device
are
contained
or
destroyed
to
minimize
re­
release
to
the
atmosphere
such
that
the
desired
emission
reduction
is
obtained.
Because
wet
scrubbers
or
WESP
are
add­
on
APCD
and
have
variable
effects
on
HAP
emissions,
today's
final
rule
specifies
that
sources
cannot
use
add­
on
control
systems
or
wet
control
devices
to
meet
PBCO.
As
part
of
this
change,
141
we
added
a
definition
of
"
wet
control
device"
to
today's
final
rule.
We
note
that
PCWP
facilities
demonstrating
compliance
with
the
PBCO
for
process
units
equipped
with
any
wet
control
device
that
effects
HAP
emissions
must
test
prior
to
the
wet
control
device.

G.
Compliance
Options
1.
Add­
on
Control
System
Compliance
Options
Comment:
We
received
a
number
of
comments
related
to
the
six
add­
on
control
systems
compliance
options
and
how
these
options
might
be
implemented
at
an
actual
PCWP
facility.
One
commenter
argued
that
the
use
of
multiple
compliance
options
for
add­
on
control
systems
will
make
it
difficult
for
State
agencies
to
determine
if
a
facility
is
actually
in
compliance.
The
commenter
pointed
out
that,
if
a
facility
tested
for
two
options
but
passed
only
one,
it
would
still
be
in
compliance.
However,
the
commenter
stated
that
the
rule
as
proposed
was
unclear
whether
a
facility
would
be
in
violation
if
the
facility
chose
to
test
for
one
option,
failed
that
test,
and
then
conducted
another
test
to
determine
compliance
with
a
different
option.
The
commenter
contended
that
this
would
constitute
a
violation
of
the
standard,
and
any
retesting
to
determine
compliance
with
a
different
option
would
not
reverse
the
initial
violation.

Therefore,
the
commenter
requested
that
we
clarify
that
the
option
to
use
the
most
beneficial
results
of
two
or
more
142
test
methods
applies
only
when
these
tests
are
conducted
during
a
single
performance
test.
According
to
the
commenter,
any
facility
that
chose
to
use
only
one
test
method
during
the
compliance
test
would
have
to
accept
the
results
of
that
test.

Other
commenters
argued
that
a
facility
should
be
able
to
switch
among
the
six
add­
on
control
options
as
needed
to
maintain
compliance.
To
illustrate
the
necessity
of
the
ability
to
switch
from
one
add­
on
control
option
to
another,

the
commenters
provided
an
example
whereby
the
operator
of
a
veneer
dryer
might
want
to
demonstrate
compliance
with
the
90
percent
THC
reduction
option
(
option
1
in
Table
1B
to
the
final
rule)
under
certain
operating
conditions
and
with
the
20
parts
per
million
by
volume
(
ppmv)
THC
option
(
option
2
in
Table
1B
to
the
final
rule)
under
other
operating
conditions.
One
of
the
commenters
also
noted
that
production
starts
and
stops
and
minor
malfunctions
are
common
at
PCWP
facilities,
and
most
of
them
do
not
affect
the
performance
of
the
air
pollution
control
device.

However,
frequent
SSM
events
resulting
in
a
low
concentration
to
the
inlet
of
the
control
device
could
affect
a
facility's
ability
to
comply
with
the
percent
reduction
option.
In
this
case,
the
commenter
stated
that
the
freedom
to
switch
compliance
options
would
be
valuable.

For
these
reasons,
the
commenters
requested
that
we
143
explicitly
state
in
the
final
PCWP
rule
that
"
a
facility
only
need
comply
with
any
one
of
the
six
options
at
any
one
time,
and
that
it
can
change
between
them
as
needed
to
fit
process
operating
conditions."

Response:
We
understand
the
commenters'
concerns
on
this
issue
and
have
written
the
final
rule
to
clarify
our
intentions
regarding
how
the
add­
on
control
system
compliance
options
should
be
implemented
at
PCWP
facilities.

The
proposed
rule
states
at
40
CFR
63.2240
that
"
You
cannot
use
multiple
compliance
options
for
a
single
process
unit."

We
included
this
provision
to
prevent
PCWP
sources
from
partitioning
emissions
from
a
single
process
unit
and
then
applying
different
control
options
to
each
portion
of
the
emissions
stream.
The
MACT
floor
determinations
and
compliance
options
were
all
based
on
the
full
flow
of
emissions
from
process
units,
and
therefore,
compliance
options
should
be
applied
to
the
same
mass
of
emissions
to
ensure
that
the
required
MACT
floor
emissions
reductions
are
achieved.
When
including
this
restriction,
we
did
not
intend
necessarily
to
limit
PCWP
facilities
to
only
one
of
the
six
options
for
add­
on
control
systems.
We
did
assume
that
each
source
would
likely
select
only
one
option,
and
that
at
any
point
in
time
for
purposes
of
assessing
compliance,
the
given
compliance
option
would
have
been
preselected
and
reflected
as
applicable
in
the
source's
permit.
144
In
fact,
in
discussions
with
industry
representatives
prior
to
proposal,
they
expressed
concern
that
the
final
rule
be
written
to
make
it
clear
that
a
source
would
only
have
to
comply
with
one
option
and
not
all
six.

Based
on
available
data,
we
expect
that
most
facilities
will
be
able
to
demonstrate
compliance
with
more
than
one
of
the
compliance
options
for
add­
on
control
systems.
When
developing
the
six
compliance
options
for
add­
on
control
systems,
we
felt
that
PCWP
facilities
would
conduct
emissions
testing
(
e.
g.,
inlet
and
outlet
testing
for
THC,

methanol,
and
formaldehyde
over
a
range
of
APCD
operating
temperatures)
and
then,
based
on
the
results
of
testing,

select
the
option
that
provides
them
with
the
most
operating
flexibility
as
well
as
an
acceptable
compliance
margin
(
i.
e.,
select
the
option
that
they
feel
will
be
easiest
for
them
to
meet
on
a
continuous
basis
under
varying
conditions).
The
operating
parameter
limit
to
be
reflected
in
the
source's
permit
(
e.
g.,
minimum
temperature)
would
be
based
on
the
measurements
made
during
the
compliant
test
runs.
For
example,
if
test
results
show
that
a
facility
can
achieve
90
percent
reduction
for
formaldehyde,
92
percent
reduction
for
methanol,
and
94
percent
reduction
for
THC,

then
the
facility
may
decide
to
reduce
THC
emissions
by
90
percent,
since
this
option
appears
to
provide
the
greatest
compliance
margin.
The
corresponding
operating
145
parameter
level
measured
during
the
testing
(
e.
g.,
minimum
15­
minute
RTO
temperature
during
a
three­
run
test)
would
then
be
set
as
the
operating
limit
in
the
permit
for
that
source.
In
this
example,
if
the
RTO
operating
temperature
drops
below
the
operating
limit,
that
would
be
a
deviation,

and
any
subsequent
retesting
done
by
the
facility
would
presumably
be
done
based
on
the
chosen
compliance
option
(
e.
g.,
reduce
THC
emissions
by
90
percent).
Determining
compliance
in
this
case
is
relatively
straightforward.

However,
we
are
aware
that
State
agencies
may
simply
refer
to
a
NESHAP
as
part
of
a
permit
and
not
stipulate
which
compliance
option
the
facility
must
meet.
In
these
cases,

we
agree
with
the
commenter
who
was
concerned
that
compliance
can
be
complicated
when
the
referenced
NESHAP
contains
multiple
options,
and
that
such
a
broad
reference
would
not
be
adequate
to
identify
the
particular
option
(
and
parameter
operating
limits)
applicable
to
the
source.
We
also
agree
that,
if
a
facility
selects
multiple
options
under
the
compliance
options
for
add­
on
control
systems,
it
should
be
required
to
conduct
all
necessary
testing
associated
with
compliance
with
the
selected
options
concurrently.
In
addition
the
facility
should
obtain
permit
terms
reflecting
these
options
as
alternate
operating
scenarios
that
clearly
identify
at
what
points
and
under
what
conditions
the
different
options
apply,
such
that
146
compliance
can
be
determined
during
a
single
time
frame.

For
example,
if
the
source
wishes
to
include
options
1,
3,

and
5
in
their
permit,
then
it
must
perform
inlet
and
outlet
testing
for
THC,
methanol,
and
formaldehyde
any
time
the
State
agency
has
reason
to
require
a
repeat
performance
test
(
if
all
three
options
are
simultaneously
applicable)
or
test
for
the
single
applicable
option
that
corresponds
to
the
given
time
and
condition
(
if
the
options
apply
as
alternate
operating
scenarios
under
different
conditions).
With
this
approach,
we
would
avoid
situations
where
a
facility
retests
to
determine
compliance
with
a
compliance
option,
fails
to
demonstrate
compliance
with
that
option,
and
then
conducts
additional
testing
to
determine
compliance
with
other
options
that
are
not
pre­
established
as
applicable
at
a
later
date.

The
final
rule
clarifies
our
intentions
regarding
the
use
of
multiple
control
options
with
respect
to
add­
on
control
systems
versus
the
combining
of
control
options
for
a
single
process
unit.
The
language
in
40
CFR
63.2240
of
the
final
rule
has
been
modified
to
remove
the
proposed
text
stating
that
a
source
"
cannot
use
multiple
compliance
options
for
a
single
process
unit"
and
replace
it
with
a
statement
that
a
source
"
cannot
combine
compliance
options
in
paragraphs
(
a)[
PBCO],
(
b)[
add­
on
control
systems
compliance
options]
or
(
c)[
emissions
averaging
provisions]
147
for
a
single
process
unit."
We
feel
that
this
wording
change
clarifies
our
intention
to
prevent
sources
from
applying
different
control
options
to
different
portions
of
the
emissions
from
a
single
process
unit,
while
leaving
open
the
potential
for
PCWP
facilities
to
be
able
to
include
multiple
compliance
options
for
add­
on
control
systems
(
i.
e.,
one
option
per
defined
operating
condition)
in
a
State
permit.
Although
add­
on
controls
are
used
in
emissions
averaging
plans
to
achieve
full
or
partial
control
of
emissions
from
a
given
process
unit,
the
emissions
from
a
single
process
unit
cannot
be
parceled
such
that
a
portion
of
the
emissions
meets
one
of
the
add­
on
control
system
compliance
options
and
another
portion
is
used
as
part
of
an
EAP.
The
final
rule
continues
to
state
that
sources
must
meet
at
least
one
of
the
six
options
for
add­
on
control
systems.

2.
PBCO
Limits
Comment:
Several
commenters
requested
that
PCWP
facilities
be
allowed
to
use
add­
on
control
methods
to
achieve
the
PBCO
limits.
The
commenters
argued
that
allowing
compliance
with
the
PBCO
using
APCD
is
consistent
with
other
MACT
rules
and
P2
approaches.
According
to
the
commenters,
numerous
NESHAP
allow
emissions
limits
to
be
reached
using
add­
on
controls,
P2
techniques,
or
a
combination
of
both.
The
commenters
stated
that
there
was
148
no
legal
or
policy
basis
for
imposing
restrictions
on
the
use
of
PBCO
in
the
PCWP
MACT.
The
commenters
also
stated
that
using
add­
on
controls
to
comply
with
PBCO
will
benefit
facilities
that
have
process
units
that
emit
low
levels
of
HAP.
According
to
the
commenter,
some
companies
have
already
implemented
P2
strategies
that
have
been
established
as
BACT
in
a
prevention
of
significant
deterioration
(
PSD)

permit.
Because
these
P2
strategies
may
fall
short
of
the
PBCO,
companies
implementing
these
strategies
would
be
unable
to
achieve
compliance
with
the
proposed
rule
without
abandoning
the
P2
strategy
and
installing
full
control.
The
commenters
also
stated
that
incorporating
add­
on
controls
in
the
PBCO
would
provide
incentives
to
find
low­
energy
pollution
control
equipment.
The
commenters
gave
an
example
whereby
part
of
the
emission
unit
exhaust
could
be
used
as
combustion
air
for
an
onsite
boiler.
The
commenters
noted
that
in
most
cases,
the
boiler
could
only
handle
a
portion
of
the
exhaust
from
multiple
dryer
stacks.
The
commenters
stated
that
by
combining
this
type
of
partial
control
approach
with
low­
temperature
drying,
a
facility
may
be
able
to
meet
the
applicable
dryer
PBCO
limit.
According
to
the
commenters,
in
this
case,
allowing
for
partial
control
would
exclude
the
need
for
RTO
technology
and
would
provide
a
net
benefit
to
the
environment
with
a
reduction
of
collateral
oxidizer
emissions.
The
commenters
gave
another
example
in
149
which
a
facility
with
a
conveyor
strand
dryer
could
send
the
exhaust
from
the
first
dryer
section
to
a
burner
and
then
send
the
heat
back
to
the
dryer;
the
emissions
from
the
remaining
dryer
sections
would
be
uncontrolled
if
the
total
emissions
were
below
the
PBCO
limit.
In
a
third
example
provided
by
the
commenters,
a
facility
would
remove
enough
HAP
to
comply
with
the
PBCO
limit
using
a
scrubber,
which
would
require
less
energy
than
incineration.

Response:
As
in
the
proposed
rule,
the
final
rule
does
not
allow
sources
to
comply
with
the
PBCO
through
the
use
of
add­
on
control
systems.
Our
intention
for
including
the
PBCO
was
to
provide
an
alternative
to
add­
on
controls
(
e.
g.,

allow
for
and
encourage
the
exploration
of
P2,
which
currently
has
not
been
demonstrated
as
achieved
by
PCWP
sources)
and
not
to
create
another
compliance
option
for
sources
equipped
with
add­
on
control
systems
that
could
inadvertently
allow
add­
on
control
equipped
systems
to
not
perform
to
expected
control
efficiencies.
Sources
equipped
with
add­
on
control
systems
already
have
six
different
compliance
options
from
which
to
choose,
in
addition
to
the
emissions
averaging
compliance
option.
We
note
that
the
six
options
for
add­
on
control
systems
are
based
on
emissions
reductions
achievable
with
MACT
control
devices
and
thus
are
a
measure
of
the
performance
of
MACT
control
devices.
This
might
not
be
true
if
a
source
combined
PBCO
and
add­
on
150
controls,
as
explained
below.

At
proposal,
we
established
PBCO
limits
for
10
process
unit
groups.
Initially,
we
felt
that
we
needed
total
HAP
data
for
at
least
one
process
unit
in
each
process
unit
group
that
was
equipped
with
a
control
system
in
order
to
establish
the
PBCO
limits.
However,
we
had
to
discard
this
approach
because
controlled
total
HAP
data
are
not
available
for
half
(
5
of
10)
of
the
process
unit
groups.
We
developed
a
number
of
other
approaches
to
establishing
PBCO,
and
then
compared
the
results
of
these
approaches,
where
possible,

with
actual
emissions
in
the
outlet
of
MACT
control
devices.

The
approach
that
yielded
results
closest
to
actual
emissions
in
the
control
device
outlets
was
an
approach
based
on
a
90
percent
reduction
from
the
average
emissions
each
process
unit
group.
Thus,
this
approach
was
the
one
that
resulted
in
limits
that
would
most
closely
represent
an
alternative
to
the
six
compliance
options
for
add­
on
control
systems.
However,
our
intention
was
not
to
develop
an
alternative
limit
to
the
six
limits
already
established
for
add­
on
control
devices.
Our
intention
was
to
develop
an
alternative
for
P2
techniques.
We
decided
to
select
an
approach
that
allows
sources
that
develop
P2
techniques
(
or
are
otherwise
inherently
low­
emitting
sources)
to
comply
and
that
reduces
HAP
emissions
without
generating
the
NOX
emissions
associated
with
incineration­
based
controls.
As
a
151
result,
we
selected
a
90
percent
reduction
from
the
highest
data
point
within
each
process
unit
group,
because
the
results
appeared
to
be
at
levels
that
would
not
preclude
the
development
of
environmentally
beneficial
P2
options
as
MACT.

If
PBCO
were
allowed
as
another
option
for
measuring
the
performance
of
add­
on
control
devices,
operators
could
run
the
APCD
so
that
the
APCD
would
not
achieve
MACT
level
emissions
reductions,
but
would
meet
the
PBCO.
We
note
that
we
did
not
develop
the
methanol
and
formaldehyde
add­
on
control
options
(
options
4
and
6
in
Table
1B
to
the
final
rule)
based
on
typical
or
maximum
levels
of
methanol
and
formaldehyde
found
in
the
outlet
of
the
control
devices,
but
instead
looked
at
the
performance
of
the
MACT
control
devices
in
reducing
these
HAP,
set
the
levels
based
on
the
method
detection
limits
for
these
compounds,
and
included
a
minimum
inlet
concentration
requirement
for
the
use
of
the
outlet
concentration
options
to
ensure
that
HAP
emissions
reductions
are
achieved.
Allowing
the
use
of
APCD
to
comply
with
PBCO
could
allow
circumvention
of
such
optimization,

which
could
render
the
MACT
control
itself
to
be
less
effective
than
MACT.

Regarding
the
other
MACT
standards
referenced
by
the
commenters,
we
agree
that
these
other
rules
may
allow
facilities
more
flexibility
in
meeting
a
production­
based
152
option
(
e.
g.,
"
lb/
ton"
emission
limit);
however,
we
cannot
allow
add­
on
controls
to
be
used
to
meet
the
PBCO
in
the
final
PCWP
rule
because
doing
so
would
render
these
limits
not
equivalent
to
the
other
compliance
options.
For
example,
consider
a
typical
wood
products
press
with
an
annual
production
rate
of
100
million
square
feet
of
board
per
year
and
a
total
HAP
emission
rate
of
1.0
pound
per
thousand
square
feet
of
board
on
a
¾
­
inch
basis
(
lb/
MSF
¾
"
).

On
an
annual
basis,
the
example
press
emits
50
tons
of
HAP
per
year.
If
the
example
press
complies
with
the
90
percent
HAP
reduction
requirement,
then
the
HAP
emissions
reductions
achieved
will
be
at
least
45
tons/
yr.
However,
if
this
same
press
were
allowed
to
comply
with
the
applicable
PBCO
limit
(
0.30
lb/
MSF
¾
"
)
using
an
APCD
(
e.
g.,
RTO),
then
the
emissions
reductions
achieved
could
be
as
little
as
35
tons/
yr
if
the
APCD
is
only
applied
to
a
portion
of
the
press'
emissions
or
if
the
APCD
is
not
operated
at
MACTlevel
efficiency.
Not
only
would
a
significantly
lower
HAP
emission
reduction
be
achieved
in
this
situation,
but
there
also
would
not
be
any
net
benefit
to
the
environment
to
justify
the
lower
HAP
reduction
(
i.
e.,
NOX
emissions
would
still
be
created).
Also,
we
wish
to
point
out
that
the
emissions
from
PCWP
process
units
are
not
insignificant,

even
when
these
units
operate
at
the
PBCO
thresholds.
For
example,
a
typical
wood
products
press
that
operates
at
the
153
applicable
PBCO
(
0.30
lb/
MSF
¾
"
)
still
emits
15
tons
of
HAP
per
year,
and
a
typical
rotary
strand
dryer
operating
at
the
applicable
PBCO
(
0.18
lb/
ODT)
emits
6
tons
of
HAP
per
year.

Therefore,
we
feel
it
is
appropriate
and
in
keeping
with
the
MACT
floor
to
require
PCWP
process
units
with
uncontrolled
HAP
emissions
above
the
PBCO
thresholds
to
achieve
the
full
90
percent
reduction
in
emissions.
We
also
wish
to
clarify
that
a
PCWP
facility
may
use
any
number
of
compliance
options,
as
long
as
these
options
are
not
combined
for
an
individual
process
unit.
For
example,
a
facility
may
choose
to
meet
the
applicable
PBCO
limit
for
one
dryer,
control
emissions
from
a
blender
to
avoid
controlling
emissions
on
the
remaining
two
dryers
as
part
of
an
emissions
average,

and
comply
with
one
of
the
add­
on
control
systems
compliance
options
for
the
press.

Regarding
the
examples
cited
by
the
commenter
as
candidates
for
a
PBCO
if
add­
on
controls
were
allowed,
we
note
that
the
final
rule
includes
a
revised
MACT
floor
for
existing
conveyor
strand
dryers,
such
that
existing
conveyor
strand
dryers
that
send
the
emissions
from
the
first
dryer
section
back
to
the
combustion
unit
that
heats
the
dryer
should
be
able
to
meet
the
rule
requirements
without
additional
controls.
In
addition,
partial
control
(
e.
g.,

routing
part
of
the
emission
stream
from
a
process
unit
to
an
onsite
combustion
unit
for
incineration)
is
allowed
as
154
part
of
an
EAP
as
long
as
the
actual
emissions
reductions
achieved
are
greater
than
or
equal
to
the
required
emissions
reductions.
When
partial
control
is
used
as
part
of
an
EAP,

the
overall
reductions
are
equivalent
to
what
would
be
achieved
if
a
source
elected
to
comply
using
the
add­
on
control
system
compliance
options;
however,
the
same
would
not
be
true
if
partial
control
were
used
to
comply
with
a
PBCO
limit.
Therefore
partial
incineration
control
is
not
allowed
in
the
PBCO.

Regarding
the
use
of
scrubbers
to
comply
with
a
PBCO,
as
stated
earlier
in
this
preamble,
the
PCWP
industry's
own
data
do
not
support
wet
scrubbers
as
a
reliable
control
technology
for
HAP,
and
sources
equipped
with
wet
control
devices
will
be
required
to
test
prior
to
the
wet
control
device
if
they
elect
to
comply
with
a
PBCO.

Comment:
Several
commenters
stated
that
PCWP
facilities
should
be
allowed
to
neglect
nondetect
HAP
measurements
for
PBCO
calculations.
The
commenters
argued
that
if
a
facility
is
forced
to
use
values
of
one­
half
the
detection
limit
for
nondetect
HAP,
that
facility
may
be
unable
to
use
PBCO
because
the
mass
of
emissions
attributed
to
undetected
compounds
may
consume
50
percent
or
more
of
the
PBCO
limit.

The
commenters
also
noted
that
the
detection
levels
measured
in
the
field
by
the
NCASI
test
method,
NCASI
IM/
CAN/
WP­

99.01,
generally
range
between
0.35
and
1
ppm,
and
the
155
detection
levels
of
the
FTIR
method
averages
about
1
ppm.

According
to
the
commenters,
even
at
these
low
concentrations,
using
one­
half
the
detection
limit
for
nondetect
compounds
can
put
the
PBCO
out
of
reach
for
a
high­
flow­
rate
PCWP
stream.
The
commenters
also
provided
a
sample
calculation
to
demonstrate
the
effect
that
the
detection
level
has
on
the
compliance
calculation.

Response:
In
responding
to
this
request,
we
reviewed
the
information
supplied
by
the
commenters
and
analyzed
the
potential
effects
of
making
the
requested
change
using
available
emissions
data.
After
reviewing
the
total
HAP
data
used
to
establish
the
PBCO
limits,
we
decided
that
sources
should
be
able
to
treat
nondetect
measurements
for
an
individual
HAP
as
zero
for
the
sole
purpose
of
determining
compliance
with
the
PBCO,
if,
and
only
if,
the
following
two
conditions
are
met:
(
1)
the
detection
limit
for
that
pollutant
is
set
at
a
value
that
is
less
than
or
equal
to
1
ppmvd,
and
(
2)
emissions
of
that
pollutant
are
nondetect
for
all
three
test
runs.
We
included
the
first
condition
to
prevent
test
contractors
from
setting
the
detection
limits
too
high,
and
thus
generating
false
zeroes.

We
selected
1
ppmvd
as
the
maximum
detection
limit
value
because
it
matches
the
detection
limits
achievable
with
the
test
methods
included
in
the
final
PCWP
rule.
We
included
the
second
condition
to
ensure
that
the
source
is
truly
low­
156
emitting,
as
evidenced
by
three
nondetect
test
runs.
If
emissions
of
the
HAP
are
detected
during
any
one
test
run,

then
any
nondetect
runs
must
be
treated
as
being
equal
to
one­
half
the
detection
limit.
The
option
to
treat
nondetect
measurements
as
zero
does
not
apply
to
the
compliance
options
for
add­
on
control
systems
because
treating
the
outlet
emissions
from
a
control
device
as
zero
would
artificially
increase
the
calculated
control
efficiency
for
that
pollutant
to
100
percent.

To
ensure
that
the
PBCO
limits
were
developed
in
a
manner
consistent
with
how
they
would
be
applied,
the
PBCO
limits
were
recalculated
using
zero
for
nondetect
measurements
when
all
test
runs
were
nondetect.
As
a
result,
the
PBCO
limit
for
reconstituted
wood
product
board
coolers
changed
from
0.015
to
0.014
lb/
MSF
¾
"
.
No
other
PBCO
limits
changed
as
a
result
of
using
zero
for
nondetects
when
calculating
the
PBCO
limits.

We
added
a
new
PBCO
limit
to
the
final
rule
for
secondary
tube
dryers.
This
new
limit
corresponds
to
our
decision
to
treat
primary
and
secondary
tube
dryers
as
separate
process
units,
as
discussed
previously
in
this
preamble.
The
final
rule
also
differentiates
between
rotary
strand
dryers
and
conveyor
strand
dryers,
as
discussed
previously
in
this
preamble;
however,
no
new
PBCO
limits
have
been
added
for
these
two
process
units
groups.
The
157
final
PBCO
limit
for
rotary
strand
dryers
is
the
same
as
the
proposed
limit
for
strand
dryers
because
the
data
used
to
establish
the
proposed
PBCO
limit
was
based
on
data
from
rotary
strand
dryers
exclusively.
We
do
not
have
the
necessary
data
to
establish
a
PBCO
for
conveyor
strand
dryers,
and
thus
the
final
rule
does
not
include
a
PBCO
limit
for
that
process
unit
group.

3.
Emissions
Averaging
Provisions
Comment:
Industry
commenters
generally
expressed
support
for
the
inclusion
of
an
emissions
averaging
program
in
the
PCWP
rule
as
proposed,
but
requested
that
the
proposed
provisions
be
modified
to
allow
for
broader
use
of
emissions
averaging
at
PCWP
facilities.
Requested
modifications
include
allowing
sources
to
receive
credit
for
achieving
emissions
reductions
greater
than
90
percent;

basing
compliance
on
a
single
pollutant;
allowing
sources
to
combine
emissions
averaging
with
PBCO;
and
allowing
sources
to
receive
credit
for
P2
alternatives
as
part
of
an
EAP.

Several
of
the
industry
commenters
contended
that
restricting
sources
to
a
maximum
control
efficiency
credit
of
90
percent
will
eliminate
an
important
incentive
for
sources
to
take
extra
steps
to
maximize
the
efficiency
of
add­
on
control
devices.
The
commenters
stated
that
allowing
credit
for
efficiencies
above
90
percent
would
encourage
those
operators
who
are
able
to
achieve
these
levels
to
run
158
controls
in
the
most
efficient
manner,
as
opposed
to
running
at
90
percent,
regardless
of
capability.
At
a
minimum,
the
commenters
requested
that
the
final
rule
allow
credit
for
control
efficiencies
greater
than
90
percent
for
those
process
units
with
no
MACT
control
requirements.
The
commenters
contended
that
because
these
emission
units
are
not
required
to
meet
any
specified
percent
reduction,
there
is
no
logical
reason
why
they
should
be
limited
to
receiving
credit
for
only
up
to
a
90
percent
reduction.

Several
commenters
suggested
that
we
allow
compliance
with
the
emission
averaging
provisions
to
be
based
on
a
single
pollutant,
specifically,
THC,
methanol,
or
formaldehyde.
With
this
modification,
sources
would
only
be
required
to
test
for
one
pollutant
instead
testing
for
all
six
HAP
that
comprise
total
HAP.

Several
commenters
requested
that
we
allow
sources
to
combine
emissions
averaging
with
the
PBCO.
Specifically,

the
commenters
requested
that
sources
be
allowed
to
apply
the
emissions
credit
generated
from
controlling
a
process
unit,
for
which
control
is
not
required,
to
another
process
unit
seeking
to
comply
with
a
PBCO
limit.
The
commenters
provided
an
example
where
a
facility
would
control
emissions
from
a
board
cooler
and
then
apply
the
resultant
emissions
reductions
to
a
press
that
had
emissions
above
the
applicable
PBCO
limit;
by
applying
the
emissions
credit
to
159
the
press,
the
press
emissions
would
be
reduced
below
the
PBCO
such
that
no
control
would
be
required
on
the
press
emissions.
The
commenters
stated
that
EPA
should
allow
combining
of
these
two
compliance
options
(
emissions
averaging
and
PBCO)
because
doing
so
would
make
the
rule
more
cost­
effective,
and
the
result
would
be
equally
beneficial
to
the
environment.

Industry
commenters
also
requested
that
we
modify
the
emission
averaging
provisions
to
allow
facilities
to
receive
emission
credits
for
P2
activities,
such
as
product
reformulation,
routing
process
unit
exhaust
to
existing
onsite
combustion
sources,
lowering
dryer
operating
temperatures,
partial
capture
and
control
of
process
unit
emissions,
increasing
use
of
hardwood
species,
production
curtailment,
and
scheduled
process
unit
downtime.
According
to
the
commenters,
not
allowing
P2
encourages
the
use
of
add­
on
controls
like
incineration,
rather
than
environmentally
beneficial
options
that
may
not
involve
addon
control
technology.
The
commenters
asserted
that
quantifying
emissions
from
P2
projects
would
not
be
difficult
under
the
PCWP
emission
averaging
program.

According
to
the
commenters,
the
facility
would
calculate
the
total
allowable
emissions
and
then
apply
a
90
percent
reduction
to
determine
the
equivalent
MACT
floor
level
of
control,
and
then
compare
the
total
emission
level
to
the
160
controlled
emission
level.

Response:
We
included
an
emission
averaging
compliance
option
in
the
proposed
rule
as
an
equivalent,
more
flexible,

and
less
costly
alternative
to
the
compliance
options
for
add­
on
control
systems.
As
explained
in
the
preamble
to
the
proposed
rule,
we
based
theUnlike
previous
MACT
standards
with
emissions
averaging
provisions,
in
part,
on
the
emissions
averaging
provisions
in
the
Hazardous
Organic
NESHAP
(
HON),
with
some
differences.
Unlike
the
HON,
the
proposed
(
and
final)
emissions
averaging
provisions
in
the
PCWP
rule
do
not
include
(
1)
limits
on
the
number
of
sources
that
can
be
included
in
an
emissions
average,
(
2)

requirements
for
a
hazard
or
risk
analysis,
or
(
3)

application
of
a
10
percent
discount
factor
to
emissions
credit
calculations.
In
addition,
the
emissions
averaging
provisions
in
the
final
PCWP
rule
require
that
credits
for
emissions
reductions
be
achieved
using
APCD,
and
that
the
EAP
be
based
on
emissions
of
the
six
predominant
HAP
emitted
from
PCWP
process
units,
referred
to
as
total
HAP.
Also,

the
emissions
averaging
provisions
do
not
allow
credit
for
reductions
beyond
90
percent.

We
disagree
with
the
commenters'
request
to
allow
credit
for
achieving
greater
than
90
percent
control
of
HAP
as
part
of
an
EAP.
We
note
that
the
90
percent
MACT
floor
level
(
upon
which
the
emissions
averaging
provisions
are
based)
161
reflects
the
inherent
variability
in
uncontrolled
emissions
from
PCWP
process
units
and
the
decline
in
performance
of
control
devices
applied
to
these
process
units.
The
data
set
used
to
establish
the
MACT
floor
is
composed
of
pointin
time
test
reports,
some
of
which
show
a
greater
than
90
percent
control
efficiency;
however,
we
selected
90
percent
as
the
MACT
floor
level
of
control
to
reflect
inherent
performance
variability.
Therefore,
it
would
be
inappropriate
to
allow
PCWP
facilities
to
receive
credit
for
similar
point­
in­
time
performance
tests
showing
greater
than
90
percent
control,
considering
that
the
same
types
of
control
technologies
would
be
used.

Regarding
the
commenters'
request
to
allow
credit
for
greater
than
90
percent
control
for
those
sources
with
no
MACT
control
requirements,
we
maintain
that
this
would
be
inappropriate
because
the
same
issues
of
emissions
variability
and
control
device
performance
apply
to
those
emission
sources,
and
they
likely
would
share
control
devices
with
PCWP
process
units
that
do
have
MACT
control
requirements.

We
have
rejected
the
commenters'
suggestion
to
base
the
emissions
averaging
provisions
on
a
single
pollutant
(
e.
g.,

THC,
methanol
or
formaldehyde),
and
retained
the
requirement
in
the
final
rule
that
the
EAP
must
be
based
on
total
HAP.

The
predominant
HAP
emitted
from
a
given
process
unit
162
varies,
with
some
process
units
emitting
methanol
as
the
predominant
HAP
and
others
emitting
formaldehyde
or
acetaldehyde
as
the
predominant
HAP.
However,
the
predominant
HAP
will
always
be
one
of
the
six
we
have
identified
in
the
definition
of
total
HAP
in
the
final
PCWP
rule.
If
we
based
the
EAP
on
only
one
pollutant,
process
units
that
emit
the
target
HAP
in
small
quantities
will
not
be
correctly
accounted
for
in
the
EAP,
resulting
in
potentially
less
stringent
control
and
greater
potential
risk
than
would
result
with
other
control
options.
As
noted
above,
we
did
not
include
a
hazard/
risk
study
as
part
of
the
proposed
EAP
because
we
were
requiring
that
the
emissions
reductions
be
based
on
total
HAP,
and
PCWP
process
units
generally
emit
the
same
six
primary
HAP,
although
in
different
quantities
and
ratios.
Basing
the
EAP
on
a
single
pollutant
would
eliminate
our
rationale
for
not
requiring
a
risk
analysis.
We
also
note
that,
while
THC
emissions
are
an
acceptable
surrogate
for
monitoring
the
performance
of
an
add­
on
control
device
(
same
control
device
mechanisms
that
reduce
THC
emissions
reduce
HAP
emissions),
THC
emissions
are
not
an
accurate
surrogate
for
establishing
baseline
HAP
emissions
for
uncontrolled
process
units,
and
thus
the
EAP
should
not
be
based
solely
on
THC
emissions.
Although
all
PCWP
process
units
emit
THC,
uncontrolled
THC
emissions
from
softwoods
are
substantially
higher
than
from
hardwoods
due
163
to
non­
HAP
compounds
(
e.
g.,
pinenes)
present
in
softwoods.

Therefore,
allowing
sources
without
add­
on
controls
to
focus
on
THC
reductions
achieved
by
increasing
hardwood
usage
might
reduce
THC
emissions
but
would
have
a
minimal
impact
on
HAP
emissions.
For
these
reasons,
we
feel
that,
for
the
purpose
of
the
final
rulemaking,
THC
should
only
be
used
as
a
surrogate
for
HAP
when
assessing
the
performance
of
an
add­
on
control
device,
and
should
not
be
used
as
a
surrogate
for
establishing
the
required
and
actual
mass
removal
of
HAP
as
part
of
an
EAP.

We
disagree
with
the
commenters
that
combining
the
emissions
averaging
option
and
PBCO
will
result
in
equivalent
emissions
reductions.
As
we
stated
in
our
response
to
previous
comments
in
this
section
regarding
PBCO,
we
developed
the
PBCO
limits
to
provide
an
option
for
sources
that
develop
P2
techniques.
The
PBCO
limits
represent
applicability
cutoffs
such
that
sources
with
emissions
below
the
applicable
PBCO
thresholds
are
not
required
to
further
reduce
those
emissions
below
MACT
levels.
By
combining
PBCO
limits
with
the
EAP,
as
proposed
by
the
commenter,
we
would
be
allowing
higher­
emitting
sources
(
i.
e.,
those
that
cannot
meet
a
PBCO
and
which
should
be
controlled)
to
escape
controls
by
artificially
lowering
their
emissions
(
using
the
credits
from
the
EAP)
to
levels
that
would
qualify
as
low­
emitting
(
below
PBCO
164
limits).
This
is
counter
to
the
intent
of
the
PBCO
and
would
result
in
lower
emissions
reductions
than
would
be
achieved
without
combining
these
two
compliance
options;

therefore,
this
does
not
represent
an
option
that
is
equivalent
to
the
MACT
floor
and
is
not
allowed
in
the
final
rule.

We
also
disagree
with
the
commenters'
suggestion
to
modify
the
emissions
averaging
provisions
to
allow
sources
to
receive
credit
for
P2
projects
because:
(
1)
compliance
options
(
i.
e.,
PBCO)
already
exist
for
any
P2
projects
that
prove
feasible,
and
(
2)
inclusion
of
currently
undemonstrated
P2
projects
within
EAP
would
unnecessarily
complicate
these
plans
and
hamper
enforcement.
As
we
noted
previously
in
this
preamble,
the
final
rule
allows
PCWP
facilities
to
use
both
P2
(
i.
e.,
the
PBCO)
and
emissions
averaging
at
the
same
facility;
sources
are
only
limited
in
that
they
cannot
apply
both
options
to
the
same
process
unit.
We
also
disagree
with
the
commenters'
assertion
that
quantifying
the
emissions
reductions
from
P2
projects
would
not
be
difficult.
Quantifying
the
emissions
reductions
associated
with
P2
projects
has
historically
been
a
contentious
issue,
especially
when
a
baseline
emission
level
must
be
established
from
which
to
calculate
the
emissions
reduction.
We
feel
that
the
same
issues
apply
for
PCWP
facilities,
especially
given
the
fact
that
P2
techniques
165
have
not
been
widely
used
or
documented
in
the
PCWP
industry.
In
contrast,
emissions
reductions
achieved
through
the
use
of
add­
on
control
systems
are
easily
documented.
The
PBCO
were
established
to
address
the
future
development
and
implementation
of
P2
techniques;
however,

the
resultant
PBCO
limits
do
not
require
that
emissions
reductions
be
determined.
Instead,
sources
simply
demonstrate
that
they
are
below
the
PBCO
limit
and
will
continue
to
operate
in
a
manner
that
ensures
they
will
remain
below
the
PBCO
limit.

Regarding
the
suggested
P2
option
of
increasing
a
facility's
use
of
hardwood
species,
in
addressing
other
issues,
commenters
stressed
the
difficulties
associated
with
maintaining
a
consistent
wood
material
flow
in
terms
of
species,
moisture
content,
etc.,
which
would
suggest
that
an
operating
condition
based
on
maintaining
a
set
level
of
wood
species
would
be
unworkable.
Furthermore,
for
veneer
dryers,
where
species
identification
(
hardwood
vs.

softwood),
and
thus
enforcement,
is
fairly
straightforward
from
the
standpoint
of
both
visual
inspection
and
endproduct
we
have
already
established
separate
MACT
floors
for
softwood
and
hardwood
veneer
dryers
(
and
require
no
further
emissions
reductions
from
hardwood
veneer
dryers).

When
the
end
product
is
particleboard
or
MDF,
and
the
raw
material
is
in
the
form
of
wood
chips,
planer
shavings,
or
166
sawdust,
determining
how
much
of
that
material
is
softwood
versus
hardwood
would
be
very
difficult,
and
likely
unenforceable.
Because
of
commenters'
concerns
that
an
operating
condition
based
on
wood
species
is
technically
unworkable
and
the
associated
enforcement
issues,
we
feel
this
option
is
not
viable.

Regarding
process
changes
such
as
reformulation,

lowering
dryer
temperature,
and
routing
process
unit
exhaust
to
existing
combustion
devices,
the
final
rule
already
includes
compliance
options
that
would
accommodate
all
of
these
strategies.
For
example,
product
reformulation
and
lowering
dryer
temperature
are
potential
P2
options,
and
the
PBCO
limits
would
apply
if
the
P2
efforts
sufficiently
lower
emissions.
The
final
PCWP
rule
distinguishes
between
green
(
high
temperature,
high
moisture)
rotary
dryers
and
dry
(
low
temperature,
low
moisture)
rotary
dryers
and
requires
no
further
emissions
reductions
from
dry
rotary
dryers.

Regarding
the
use
of
existing
combustion
units
as
control
devices,
the
final
rule
allows
sources
to
route
emissions
to
onsite
combustion
units
for
incineration.
The
final
rule
also
allows
sources
to
control
a
portion
of
a
process
unit's
emission
stream
as
part
of
an
emissions
average.
However,

we
disagree
that
incineration
of
emissions
in
onsite
process
units
is
a
P2
measure.
Therefore,
compliance
with
the
PBCO
using
process
incineration
is
not
allowed
in
the
final
rule.
167
The
add­
on
control
system
and
emissions
averaging
compliance
options
are
available
for
process
units
controlled
by
routing
exhaust
to
an
onsite
combustion
unit.

The
final
PCWP
rule
does
not
allow
production
curtailment
to
be
counted
as
part
of
an
EAP.
As
stated
in
the
preamble
to
the
proposed
rule
(
68
FR
1276,
January
9,

2003),
we
do
not
have
facility­
wide
uncontrolled
emissions
data
and
facility­
wide
controlled
emissions
data
for
each
PCWP
facility
to
determine
the
baseline
emissions
and
percent
reduction
in
HAP
achieved
by
each
facility.

Therefore,
the
MACT
floor
is
not
based
on
facility­
wide
emissions
and
emissions
reductions
achieved
during
year
"
x."

Instead,
the
MACT
floor
is
based
on
(
1)
the
presence
or
absence
of
certain
MACT
controls
(
in
place
as
of
April
2000)

on
certain
types
of
process
units
and
(
2)
test
data
showing
that
these
controls
reduce
emissions
by
greater
than
or
equal
to
90
percent.
We
applied
the
MACT
floor
methodology
at
the
process
unit
level
because
we
had
the
most
accurate
data
at
the
process­
unit
level,
making
this
approach
the
most
technically
and
legally
sound.
The
PCWP
industry
is
very
dynamic,
with
frequent
shutdowns
of
equipment
for
maintenance,
and
occasionally
longer
shutdowns
(
e.
g.,

monthlong
if
demand
drops.
The
final
PCWP
rule
requires
emissions
from
specified
process
units
at
impacted
PCWP
facilities
to
be
reduced
by
90
percent,
regardless
of
what
168
the
levels
of
emissions
are
for
those
facilities
in
a
particular
year.
Therefore,
implementation
of
the
final
PCWP
rule
at
individual
PCWP
facilities
will
result
in
greater
emissions
reductions
in
years
of
greater
production
and
lesser
emissions
reductions
during
years
of
lower
production.
As
mentioned
in
the
response
to
the
previous
comment,
the
emissions
averaging
provisions
must
achieve
emissions
reductions
that
are
greater
than
or
equal
to
those
that
would
be
achieved
using
the
add­
on
control
system
compliance
options,
which
specify
which
process
units
must
be
controlled.
If
we
allowed
credit
for
production
curtailments,
the
overall
emissions
reductions
achieved
through
the
emissions
averaging
provisions
would
not
be
equivalent
to
what
would
be
achieved
through
the
use
of
the
add­
on
control
system
compliance
options,
and
therefore,
the
EAP
would
not
be
a
MACT­
equivalent
alternative.
For
example,
if
we
allowed
production
curtailments
to
count
toward
an
emissions
average,
then
a
facility
that
shuts
down
one
of
two
parallel
production
lines
(
each
of
which
includes
dryers
and
a
press,
plus
HAP­
emitting
equipment
that
does
not
have
associated
control
requirements)
may
not
be
required
to
control
the
emissions
from
any
of
the
dryers
or
press
on
the
remaining
production
line.
However,
if
the
same
facility
opted
to
comply
with
the
add­
on
control
system
compliance
options,
then
it
would
be
required
to
control
the
169
press
and
dryer
emissions
from
the
remaining
production
line
by
90
percent
regardless
of
whether
or
not
the
other
production
line
was
shut
down.
In
order
to
maintain
equivalency
between
the
emissions
averaging
provisions
and
the
add­
on
control
system
compliance
options
and
to
preserve
the
required
HAP
emissions
reductions,
the
final
PCWP
rule
does
not
allow
production
curtailment
to
be
counted
as
part
of
an
EAP.

Comment:
One
commenter
objected
to
the
inclusion
of
the
emissions
averaging
option
in
the
rule
primarily
because
of
the
lack
of
a
requirement
to
conduct
a
hazard
or
risk
study.

This
commenter
asserted
that
removing
a
certain
mass
of
HAP
regardless
of
identity
is
not
equivalent
to
the
other
compliance
options,
and
when
the
dose­
response
and
exposure
data
are
examined,
it
should
be
obvious
that
trading
one
HAP
for
another
to
meet
a
RMR
is
not
an
acceptable
option.
The
commenter
noted
that
there
are
currently
no
methods
for
weighting
the
toxicity
of
HAP
and
that
the
effects
of
simultaneous
exposure
to
several
HAP
also
are
unknown.
The
commenter
contended
that,
because
80
percent
of
the
PCWP
facilities
in
the
U.
S.
pose
cancer
risks
greater
than
1
in
1
million,
emissions
reductions
should
be
required
at
these
facilities
rather
than
allowing
potential
increases
in
toxic
emissions
from
certain
process
units.

Response:
We
disagree
with
commenter's
assertion
that
170
inclusion
of
the
emissions
averaging
provisions
will
potentially
increase
toxic
emissions
at
certain
PCWP
process
units.
As
stated
in
the
preamble
to
the
proposed
rule
(
68
FR
1289,
January
9,
2003),
PCWP
facilities
have
fewer
pollutants
of
concern
(
as
compared
to
HON
facilities)
and
are
likely
to
have
similar
HAP
emissions
from
the
emission
points
(
process
units)
that
would
be
used
to
generate
debits
and
credits.
The
PCWP
facilities
emit
six
primary
HAP,

whereas
HON
facilities
may
emit
over
140
different
HAP.
The
PCWP
facilities
choosing
to
comply
through
emission
averaging
must
account
for
the
emissions
of
the
six
primary
HAP
(
total
HAP),
which
represent
greater
than
96
percent
of
the
mass
of
HAP
emitted
from
PCWP
process
units.
Because
the
MACT
control
technologies
are
effective
in
reducing
the
emissions
of
all
six
of
these
HAP,
and
the
emissions
averaging
provisions
require
the
use
of
add­
on
control
technologies
for
credit­
generating
sources
in
an
EAP,
we
feel
that
the
emissions
averaging
provisions
will
achieve
a
hazard/
risk
benefit
comparable
to
what
would
be
achieved
through
point­
by­
point
compliance.
Although
the
final
rule
does
not
require
a
hazard/
risk
study,
States
will
still
have
the
discretion
to
require
a
PCWP
facility
that
requested
approval
of
an
EAP
to
conduct
a
hazard/
risk
study
(
or
could
preclude
the
facility
from
using
emissions
averaging
altogether).
171
Comment:
Several
commenters
requested
that
we
write
the
definitions
of
some
of
the
variables
used
in
the
emissions
averaging
equations
in
the
final
rule
to
clarify
that
sources
can
take
credit
for
emission
reductions
achieved
through
partial
control
of
debit­
generating
process
units.

Response:
We
agree
with
the
commenters'
request
and
have
written
the
definitions
of
some
of
the
variables
used
in
the
emissions
averaging
equations
in
today's
final
rule
to
clarify
that
partial
credits
generated
from
debitgenerating
process
units
that
are
undercontrolled
can
be
included
in
the
calculation
of
the
AMR.
For
example,
a
PCWP
facility
may
decide
to
control
30
percent
of
the
emissions
from
a
green
rotary
dryer
and
80
percent
of
the
emissions
from
a
blender
as
part
of
an
EAP
in
order
to
achieve
a
HAP
reduction
that
is
the
same
as
or
greater
than
what
the
facility
would
have
achieved
by
controlling
the
green
dryer
emissions
alone
by
90
percent.
In
this
example,
the
green
rotary
dryer
is
a
debit­
generating
unit
because
it
has
MACT
control
requirements;
however,
the
green
dryer
can
receive
credit
in
the
AMR
calculation
for
any
partial
emissions
reductions
that
are
achieved.

H.
Testing
and
Monitoring
Requirements
1.
Test
Methods
Comment:
Several
commenters
noted
that
one
of
the
NCASI
test
methods,
NCASI
IM/
CAN/
WP­
99.01,
has
been
updated,
and
172
requested
that
the
final
rule
refer
to
the
revised
version.

One
of
the
commenters
provided
a
revised
version
of
the
method,
identified
as
NCASI
IM/
CAN/
WP­
99.02.
This
commenter
noted
that
the
trained
NCASI
sampling
team
was
able
to
get
good
consistent
results
with
the
original
version
of
the
method
both
in
the
laboratory
and
in
the
field,
but
that
sampling
contractors
had
difficulty
obtaining
valid
results.

The
commenter
maintained
that
the
revised
version
is
easier
to
understand,
includes
more
details,
and
reflects
the
comments
of
the
contractors
that
have
experience
with
the
original
method.
The
commenter
also
stated
that
the
quality
assurance
requirements
were
strengthened
in
the
revised
version
to
ensure
good
results.
Several
commenters
also
noted
that
NCASI
is
currently
developing
a
new
method
for
measuring
the
six
HAP
(
total
HAP)
listed
in
the
PCWP
rule
as
proposed.
Therefore,
the
commenters
requested
that
we
include
language
in
the
final
rule
that
would
allow
PCWP
facilities
to
use
future
methods
once
they
have
been
reviewed
by
EPA
and
have
passed
Method
301
validation
at
a
PCWP
plant.

Response:
We
reviewed
the
revised
NCASI
method
IM/
CAN/
WP­
99.02
supplied
by
the
commenter
and
agree
that
the
revised
method
is
appropriate
for
measurement
of
the
six
HAP
that
comprise
"
total
HAP;"
therefore,
we
have
included
NCASI
IM/
CAN/
WP­
99.02
in
the
today's
final
rule.
Regarding
the
173
development
of
future
test
methods,
if
and
when
a
new
method
for
measuring
HAP
from
PCWP
sources
is
developed
and
validated
via
EPA
Method
301,
we
will
issue
an
amendment
to
the
final
rule
to
include
the
use
of
that
method
as
an
alternative
to
the
methods
included
in
the
final
rule
for
measuring
total
HAP
(
i.
e.,
NCASI
Method
IM/
CAN/
WP/
99.02
and
EPA
Method
320­­
Measurement
of
Vapor
Phase
Organic
and
Inorganic
Emission
by
Extractive
FTIR).
In
the
meantime,
if
the
new
method
is
validated
using
Method
301,
then
the
Method
301
results
can
be
used
to
request
approval
to
use
the
new
method
on
a
site­
specific
basis.

Comment:
Several
commenters
noted
that
the
tracer
gas
method
for
determining
capture
efficiency,
developed
by
a
PCWP
company
and
included
in
the
proposed
rule
(
68
FR
1276,

appendix
A
to
40
CFR
part
63),
is
a
work
in
progress.
These
commenters
included
with
their
comments
a
copy
of
field
validation
tests
conducted
at
a
PCWP
facility.
The
commenters
noted
that
future
tests
are
planned
using
the
tracer
gas
method
and
that
the
results
of
these
tests
should
help
EPA
improve
the
use
and
application
of
the
proposed
tracer
gas
test.

Response:
We
have
reviewed
the
results
of
the
first
field
validation
test
of
the
tracer
gas
method
and
note
that
the
commenters
did
not
provide
any
specific
recommendations
for
modifying
the
tracer
gas
method
as
it
was
proposed.
174
Therefore,
other
than
a
few
minor
wording
changes,
we
did
not
make
any
substantive
changes
to
the
tracer
gas
method
in
the
final
rule.
If
the
results
of
subsequent
field
tests
demonstrate
a
need
to
(
further)
modify
the
tracer
gas
method,
we
will
issue
an
amendment
to
the
final
rule
to
incorporate
the
necessary
changes.

2.
Sampling
locations
Comment:
Several
commenters
recommended
that
the
final
rule
be
reworded
to
clearly
state
that
inlet
sampling
should
take
place
at
the
functional
inlet
of
a
control
device
sequence
or
at
the
primary
HAP
control
device
inlet.
For
example,
the
commenters
noted
that
the
final
rule
needs
to
clarify
that
sampling
should
take
place
at
the
inlet
of
a
WESP
that
precedes
an
RTO
instead
of
between
the
two
devices.
The
commenters
noted
that
many
WESP­
RTO
control
systems
are
too
closely
coupled
to
allow
for
a
sampling
location
in
between
that
meets
the
requirements
of
Method
1
or
1A,
40
CFR
60,
appendix
A.

Response:
We
agree
with
the
commenters
and
have
written
the
final
PCWP
rule
to
indicate
that,
for
HAP­
altering
controls
in
sequence,
such
as
a
wet
control
device
followed
by
a
thermal
oxidizer,
sampling
sites
must
be
located
at
the
functional
inlet
of
the
control
sequence
(
e.
g.,
prior
to
the
wet
control
device)
and
at
the
outlet
of
the
control
sequence
(
e.
g.,
thermal
oxidizer
outlet)
and
prior
to
any
175
releases
to
the
atmosphere.
In
addition,
as
discussed
previously
in
this
preamble,
the
final
rule
also
clarifies
that
facilities
demonstrating
compliance
with
a
PBCO
limit
for
a
process
unit
equipped
with
a
wet
control
device
must
locate
the
sampling
site
prior
to
the
wet
control
device.

3.
Testing
Under
Representative
Operating
Conditions
Comment:
Several
commenters
objected
to
the
proposed
requirement
to
test
process
units
under
representative
operating
conditions.
The
commenters
argued
that,
because
the
initial
compliance
tests
determine
the
outer
limits
of
compliance,
those
tests
should
be
conducted
at
the
boundaries
of
expected
performance
for
the
process
and
control
units.
These
commenters
noted
that
testing
at
representative
conditions
would
not
accurately
simulate
true
operating
conditions,
and
thus,
the
operating
parameter
limits
would
be
too
narrow.
Therefore,
the
commenters
contended
that
the
final
rule
should
specify
that
initial
compliance
tests
should
be
conducted
at
the
extremes
of
the
expected
operating
range
for
the
parameter
and
control
device
function.
In
addition,
one
of
the
commenters
noted
that
the
testing
provisions
should
also
address
potential
conflicts
with
traditional
State
requirements
to
test
at
maximum
or
design
conditions.

Response:
The
proposed
rule
defined
representative
operating
conditions
as
those
conditions
under
which
"
the
176
process
unit
will
typically
be
operating
in
the
future,

including
use
of
a
representative
range
of
materials[...]

and
representative
temperature
ranges."
We
disagree
that
the
proposed
requirement
to
test
under
representative
operating
conditions
will
conflict
with
State
requirements
and
result
in
operating
parameter
limits/
ranges
that
are
too
narrow.
We
wish
to
clarify
that
the
definition
of
representative
operating
conditions
refers
to
the
full
range
of
conditions
at
which
the
process
unit
will
be
operating
in
the
future.
We
expect
that
facilities
will
test
under
a
variety
of
conditions,
including
upper
and/
or
lower
bounds,

to
better
define
the
minimum
or
maximum
operating
parameter
limit
or
broaden
their
operating
limit
ranges
(
where
applicable).
For
example,
if
a
facility
generally
operates
a
process
unit
(
equipped
with
an
RTO)
under
conditions
that
require
the
RTO
to
be
operated
at
a
minimum
temperature
of
1450

F
to
ensure
compliance
with
the
standards,
but
at
other
times
operates
that
process
unit
under
conditions
such
that
the
minimum
RTO
operating
temperature
must
be
1525

F
to
ensure
compliance,
then
the
facility
has
two
options.
One
option
is
for
the
facility
to
incorporate
both
of
these
operating
conditions
into
their
permit
such
that
they
are
subject
to
two
different
operating
parameter
limits
(
minimum
temperatures),
one
for
each
(
defined)
operating
condition.

As
an
alternative,
the
facility
could
decide
to
comply
with
177
the
parameter
limit
associated
with
the
worst­
case
operating
conditions
(
most
challenging
conditions
for
the
RTO),
which
in
this
example
would
correspond
to
maintaining
a
minimum
RTO
operating
temperature
of
1525

F,
and
thus,
they
could
demonstrate
continuous
compliance
regardless
of
the
operating
condition
as
long
as
they
maintained
the
RTO
temperature
at
or
above
1525

F.
We
have
revised
the
monitoring
requirements
for
process
units
without
control
devices
to
allow
these
sources
to
establish
a
range
of
compliant
parameter
values.
In
addition,
those
PCWP
facilities
operating
biofilters
must
maintain
their
biofilter
bed
temperature
within
the
range
established
during
the
initial
performance
test
and,
if
available,

previous
performance
tests.
If
the
final
PCWP
rule
required
testing
at
maximum
operating
conditions,
there
would
be
no
way
for
facilities
to
identify
their
operating
parameter
ranges.
For
these
reasons,
we
maintain
that
the
requirement
to
test
at
representative
operating
conditions
is
appropriate
for
the
PCWP
rule.

4.
Process
Incineration
Monitoring
Requirements
Comment:
Several
commenters
expressed
approval
for
the
proposed
exemption
from
testing
and
monitoring
requirements
for
those
process
units
with
emissions
introduced
into
the
flame
zone
of
an
onsite
combustion
unit
with
a
capacity
greater
than
or
equal
to
44
megawatts
(
MW)
(
150
million
178
Btu/
hr).
In
addition,
several
of
these
commenters
requested
that
we
expand
upon
this
exemption
in
the
final
rule.

First,
the
commenters
requested
that
we
extend
the
exemption
to
include
situations
where
the
process
unit
exhaust
is
introduced
into
the
combustion
unit
with
the
combustion
air.

The
commenters
noted
that
we
had
included
such
exemptions
in
the
HON
(
40
CFR
part
63,
subpart
G)
and
in
the
Pulp
and
Paper
Cluster
Rule
(
40
CFR
part
63,
subpart
S)
in
recognition
of
the
fact
that
boilers
greater
than
44
MW
typically
had
greater
than
¾
­
second
residence
time,
ran
hotter
than
1,500

F,
and
usually
had
destruction
efficiencies
greater
than
98
percent
(
see
65
FR
3909,

January
25,
2000,
and
65
FR
80762,
December
22,
2000,
at
§
63.443(
d)(
4)(
ii)).
The
commenters
stated
that
the
design
and
construction
of
PCWP
boilers
follow
the
same
principles
that
would
allow
for
these
operating
conditions.
Second,

the
commenters
requested
that
we
also
exempt
smaller
combustion
units
(
less
than
44
MW,
or
150
million
Btu/
hr)

from
the
testing
and
monitoring
requirements
if
the
process
unit
exhaust
is
introduced
into
the
flame
zone
of
the
combustion
unit.
The
commenters
noted
that
most
of
the
combustion
units
associated
at
PCWP
facilities
are
smaller
units
and
that
testing
of
these
units
can
be
complicated
by
their
configuration
and
integration
with
other
process
units.
179
Response:
After
reviewing
available
information
on
process
incineration
at
PCWP
facilities,
we
decided
to
include
smaller
combustion
units
in
the
exemption
from
testing
and
monitoring
requirements
if
the
process
exhaust
enters
into
the
flame
zone.
As
part
of
this
change,
we
have
included
definitions
of
"
flame
zone"
and
"
combustion
unit"

in
the
final
rule.
However,
we
decided
not
to
include
an
exemption
for
PCWP
combustion
units
that
introduce
the
process
exhaust
with
the
combustion
air.
As
noted
by
the
commenters,
the
HON
and
the
final
pulp
and
paper
MACT
I
rule
exempt
from
testing
and
monitoring
requirements
combustion
devices
with
heat
input
capacity
greater
than
or
equal
to
44
MW.
The
HON
also
exempts
from
testing
and
monitoring
combustion
devices
with
capacity
less
than
44
MW
if
the
exhaust
gas
to
be
controlled
enters
with
the
primary
fuel.

If
the
exhaust
gas
to
be
controlled
does
not
enter
with
the
primary
fuel,
then
testing
and
continuous
monitoring
of
firebox
temperature
is
required
by
the
HON.
Similarly,
the
final
pulp
and
paper
MACT
I
rule
exempts
from
testing
and
monitoring
requirements
combustion
devices
(
including
recovery
furnaces,
lime
kilns,
boilers,
or
process
heaters)

with
capacity
less
than
44
MW
if
the
exhaust
stream
to
be
controlled
enters
into
the
flame
zone
or
with
the
primary
fuel.
Similar
to
the
HON
and
pulp
and
paper
MACT
I
rules,

the
final
PCWP
rule
extends
the
exemption
from
testing
and
180
monitoring
requirements
to
combustion
units
with
heat
input
capacity
less
than
44
MW,
provided
that
the
exhaust
gas
to
be
treated
enters
into
the
combustion
unit
flame
zone.
If
the
exhaust
gas
enters
into
the
combustion
unit
flame
zone,

the
required
90
percent
control
efficiency
may
be
assumed.

If
the
exhaust
gas
does
not
enter
into
the
flame
zone,
then
the
testing
and
monitoring
requirements
for
thermal
oxidizers
will
apply.

As
noted
by
the
commenter,
the
HON
and
the
final
pulp
and
paper
MACT
I
rule
exempted
boilers
(
and
recovery
furnaces
at
pulp
and
paper
mills)
with
heat
input
capacity
greater
than
44
MW
from
testing
and
monitoring
requirements
because
performance
data
showed
that
these
large
boilers
achieve
at
least
98
percent
combustion
of
HAP
when
the
emission
streams
are
introduced
with
the
primary
fuel,
into
the
flame
zone,
or
with
the
combustion
air.
Lime
kilns
at
pulp
and
paper
mills
were
excluded
from
this
provision
because
we
did
not
have
any
data
to
show
that
lime
kilns
can
achieve
the
required
destruction
efficiency
when
the
HAP
emission
stream
is
introduced
with
the
combustion
air.

Therefore,
lime
kilns
at
pulp
and
paper
mills
that
accept
HAP
emission
streams
must
introduce
the
stream
into
the
flame
zone
or
with
the
primary
fuel.
We
do
not
have
the
data
to
show
that
the
design
and
construction
of
large
(
greater
than
44
MW)
combustion
units
at
PCWP
plants
would
181
be
similar
to
boilers
found
at
pulp
and
paper
mills.

Furthermore,
combustion
units
at
PCWP
plants
with
heat
input
capacity
of
greater
than
44
MW
are
less
prevalent
than
smaller
(
i.
e.,
less
than
44
MW)
PCWP
combustion
units,
and
many
of
these
smaller
combustion
units
are
not
boilers.
As
stated
above,
the
final
rule
exempts
these
smaller
combustion
units
from
the
testing
and
monitoring
requirements
provided
that
the
HAP
emission
stream
is
introduced
into
the
flame
zone.
For
these
reasons,
the
final
PCWP
rule
does
not
extend
the
exemption
from
testing
and
monitoring
to
those
boilers
greater
than
44
MW
that
introduce
the
HAP
emission
stream
with
the
combustion
air.

5.
Selection
of
Operating
Parameter
Limits
for
Add­
on
Control
Systems
Comment:
Several
commenters
stated
that
the
inlet
static
pressure
to
a
thermal
or
catalytic
oxidizer
is
not
a
reliable
indicator
of
the
flow
through
the
oxidizer,
the
destruction
efficiency,
or
the
capture
efficiency.
The
commenters
also
noted
that
the
preamble
to
the
PCWP
rule
stated
that
monitoring
the
static
pressure
can
indicate
to
the
operator
when
there
is
a
problem
such
as
plugging.

However,
the
commenters
stated
that
static
pressure
is
usually
the
last
indicator
of
these
types
of
control
device
problems.
As
discussed
in
the
promulgation
BID,
the
commenters
agreed
that
measuring
those
parameters
helps
to
182
assess
the
overall
condition
of
the
oxidizer
but
provided
reasons
why
setting
limits
on
these
parameters
is
inappropriate.
The
commenters
further
noted
that
monitoring
the
static
pressure
helps
to
control
the
speed
of
the
fan
or
the
oxidizer
dampers
so
that
all
the
air
flows
are
balanced.

According
to
the
commenters,
static
pressure
is
adjusted
to
avoid
vacuum
conditions
in
the
ductwork
of
multiple­
dryer
systems
treated
by
one
control
device
when
one
dryer
is
shut
down,
to
improve
emission
collection
efficiency
and
prevent
fugitive
emissions,
and
to
adjust
the
pressure
drop
across
a
bag
filter
as
it
fills
with
particulates,
among
other
reasons.
However,
the
commenters
stated
that,
if
operators
are
required
to
keep
the
static
pressure
within
an
operating
range,
it
will
limit
their
ability
to
maintain
capture
efficiency.
The
commenters
expressed
similar
concerns
regarding
air
flow
rate
monitoring
and
noted
that
numerous
factors
affect
the
air
flow
through
the
control
device,

including
the
rate
of
water
removal
in
dryers,
leakage
of
tramp
air
into
the
process,
the
number
of
processes
operating
for
control
units
that
receive
emissions
from
multiple
production
units,
and
the
overall
production
speed
due
to
process
adjustments.
The
commenters
noted
that,
in
those
cases
where
air
flow
to
the
oxidizer
is
not
constant,

monitoring
the
air
flow
through
the
oxidizer
will
not
be
an
accurate
measure
of
capture
efficiency.
183
Response:
After
reviewing
the
information
provided
by
the
commenters,
we
agree
that,
while
monitoring
the
static
pressure
or
air
flow
rate
helps
to
assess
the
overall
condition
of
the
oxidizer
and
provides
an
indication
that
emissions
are
being
captured,
setting
operating
limits
on
these
parameters
is
not
appropriate
for
the
reasons
given
by
the
commenters.
Therefore,
today's
final
rule
does
not
include
the
proposed
requirement
to
monitor
the
static
pressure
or
air
flow
rate
for
thermal
and
catalytic
oxidizers.

Comment:
Several
commenters
requested
that
we
modify
the
procedures
for
determining
the
minimum
operating
temperature
(
operating
limit)
for
thermal
and
catalytic
oxidizers.
The
commenters
stated
that,
due
to
the
normal
variation
in
combustion
temperatures,
a
facility
will
have
to
perform
the
initial
compliance
test
at
lower­
than­
normal
temperature
conditions
to
ensure
that
the
minimum
combustion
temperature
will
be
set
at
a
level
that
they
can
continuously
meet.
The
commenters
requested
that
we
allow
facilities
to
operate
the
thermal
oxidizers
up
to
50
°
F
lower
than
the
average
obtained
by
the
performance
test
and
allow
facilities
to
operate
RCO
at
a
level
that
is
100
°
F
above
the
minimum
operating
temperature
of
the
catalyst.
The
commenters
also
noted
that,
when
the
THC
concentration
in
the
inlet
is
high,
the
RCO
will
not
need
any
additional
heat
184
and
it
can
operate
at
temperatures
higher
than
the
set
point.
Therefore,
if
the
initial
compliance
tests
are
conducted
under
these
conditions,
the
operating
temperature
limit
will
be
too
high
for
production
rates
at
less
than
full
capacity.

Commenters
also
stated
that,
for
RCO,
the
thermocouple
should
be
placed
in
a
location
to
measure
the
temperature
of
the
gas
in
the
combustion
chamber
between
the
catalyst
beds
instead
of
in
a
location
to
measure
the
gas
stream
before
it
reaches
the
catalyst
bed.
The
commenters
noted
that,

because
the
gas
flow
reverses
direction
in
RCO,
the
inlet
temperature
monitor
will
not
consistently
measure
the
gas
at
the
same
point
in
the
process
such
that
sometimes
the
gas
temperature
will
be
recorded
after
the
catalyst
beds
instead
of
before.
The
commenters
further
noted
that
placement
of
the
monitor
inside
the
combustion
chamber
would
eliminate
the
need
for
multiple
monitors
and
avoid
problems
such
as
overheating
and
burnout
of
the
catalyst
media
caused
by
the
temperature
delay
between
the
burner
and
the
RCO
inlet.

Response:
We
disagree
with
the
commenters'
request
to
include
a
50

F
margin
around
the
minimum
operating
temperature
established
during
the
thermal
oxidizer
compliance
test.
In
general,
selection
of
the
representative
operating
conditions
for
both
the
process
and
the
control
device
for
conducting
the
performance
test
is
an
185
important,
and
sometimes
complex,
task.
We
maintain
that
establishing
the
add­
on
control
device
operating
limit
at
the
level
demonstrated
during
the
performance
test
is
appropriate.
We
note
that
the
PCWP
rule
as
proposed
allows
a
facility
to
select
the
temperature
operating
limits
based
on
site­
specific
operating
conditions,
and
the
facility
is
able
to
consider
the
need
for
temperature
fluctuations
in
this
selection.
The
PCWP
rule
as
proposed
requires
that
the
operating
limit
be
based
on
the
average
of
the
three
minimum
temperatures
measured
during
a
3­
hour
performance
test
(
rather
than
on
the
average
temperature
over
the
3­
hour
period,
for
example)
to
accommodate
normal
variation
during
operation
and
ensure
that
the
minimum
temperature
established
represents
the
lowest
of
the
temperatures
measured
during
the
compliant
test.
For
example,
during
a
3­
hour,
three­
run
performance
test,
the
operating
limit
would
be
determined
by
averaging
together
the
lowest
15­

minute
average
temperature
measured
during
each
of
the
three
runs.
However,
continuous
compliance
with
the
operating
limit
is
based
on
a
3­
hour
block
average.
For
a
typical
3­

hour
set
of
data,
this
means
that
the
3­
hour
block
average
will
be
higher
than
the
average
of
the
three
lowest
15­

minute
averages,
so
the
temperature
monitoring
provisions
already
have
a
built­
in
compliance
margin.
In
addition,
the
final
rule
allows
PCWP
facilities
to
conduct
multiple
186
performance
tests
to
set
the
minimum
operating
temperature
for
RCO
and
RTO,
so
PCWP
sources
would
have
the
option
to
conduct
their
own
studies
(
under
a
variety
of
representative
operating
conditions)
in
order
to
establish
the
minimum
operating
temperature
at
a
level
that
they
could
maintain
and
that
would
provide
them
with
an
acceptable
compliance
margin.
We
feel
these
provisions
allow
sufficient
flexibility,
and
an
additional
tolerance
for
a
50oF
temperature
variation
is
not
necessary.
Therefore,
the
final
rule
does
not
allow
facilities
to
operate
thermal
oxidizers
50
°
F
lower
than
the
average
temperature
during
testing.

With
regard
to
RCO,
we
agree
with
the
commenters
that
when
the
THC
concentration
in
the
inlet
is
high,
the
RCO
will
not
need
any
additional
heat
and
it
can
operate
at
temperatures
higher
than
the
set
point.
Therefore,
if
the
initial
compliance
tests
are
conducted
under
these
conditions,
the
operating
temperature
limit
will
be
too
high
for
production
rates
at
less
than
full
capacity.
However,

the
final
rule
requires
emissions
testing
under
representative
operating
conditions
and
not
maximum
operating
conditions.
In
addition,
we
do
not
agree
with
the
commenter's
solution
to
set
the
operating
limit
at
100
°
F
above
the
minimum
operating
(
design)
temperature
of
the
catalyst.
As
with
RTO,
we
feel
it
is
incumbent
upon
the
187
facility
to
demonstrate
performance
and
establish
the
operating
limits
during
the
compliance
demonstration
test.

Therefore,
the
final
rule
requires
the
facility
to
establish
the
minimum
catalytic
oxidizer
operating
temperature
during
the
compliance
test.
However,
as
noted
below,
we
have
provided
more
flexibility
to
the
facility
regarding
temperature
monitoring
for
RTO
and
RCO.

We
recognize
that
in
a
typical
RTO
and
RCO
the
combustion
chamber
contains
multiple
burners,
and
that
each
of
these
burners
may
have
multiple
thermocouples
for
measuring
the
temperature
associated
with
that
burner.
The
final
rule
requires
establishing
and
monitoring
a
minimum
firebox
temperature
for
RTO.
In
an
RTO,
the
minimum
firebox
temperature
is
actually
represented
by
multiple
temperature
measurements
for
multiple
burners
within
the
combustion
chamber.
Thus,
the
final
rule
clarifies
that
facilities
operating
RTO
may
monitor
the
temperature
in
multiple
locations
within
the
combustion
chamber
and
calculate
the
average
of
the
temperature
measurements
to
use
in
establishing
the
minimum
firebox
temperature
operating
limit.

Regarding
RCO,
we
agree
with
the
commenters
that,

because
the
gas
flow
reverses
direction
in
RCO,
the
inlet
temperature
monitor
will
not
consistently
measure
the
gas
at
the
same
point
in
the
process,
such
that
sometimes
the
gas
188
temperature
will
be
recorded
after
the
catalyst
beds
instead
of
at
the
inlet
to
the
beds.
We
did
not
intend
to
require
the
separate
measurement
of
each
inlet
temperature
by
switching
the
data
recording
back
and
forth
to
coincide
with
the
flow
direction
into
the
bed.
The
intention
is
to
monitor
the
minimum
temperature
of
the
gas
entering
the
catalyst
to
ensure
that
the
minimum
temperature
is
maintained
at
the
operating
level
during
which
compliance
was
demonstrated.
This
can
be
accomplished
by
measuring
the
temperature
in
the
regenerative
canisters
at
one
or
more
locations.
Measuring
the
inlet
temperatures
of
each
catalyst
bed
and
then
determining
the
average
temperature
for
all
catalyst
beds
is
one
approach.
Even
though
some
of
the
beds
are
cooling
and
others
are
heating,
the
average
across
all
of
the
catalyst
beds
should
not
vary
significantly.
Another
acceptable
alternative
is
monitoring
the
combustion
chamber
temperature,
as
suggested
by
the
commenters.
The
monitoring
location(
s)
selected
by
the
facility
may
depend
on
the
operating
conditions
(
i.
e.,
THC
loading
to
the
unit)
during
the
performance
test
and
how
the
unit
is
expected
to
be
operated
in
the
future.
The
objective
is
to
establish
monitoring
and
operating
limits
that
are
representative
of
the
conditions
during
the
compliance
demonstration
test(
s)
and
representative
of
the
temperature
to
which
the
catalyst
is
exposed.
We
recognize
189
the
need
for
flexibility
in
selecting
the
temperature(
s)
to
be
monitored
as
operating
limits
for
RCO.
Therefore,
the
final
rule
provides
flexibility
by
allowing
facilities
with
RCO
to
choose
between
basing
their
minimum
RCO
temperature
limit
on
the
average
of
the
inlet
temperatures
for
all
catalyst
beds
or
the
average
temperature
within
the
combustion
chamber.
If
there
are
multiple
thermocouples
at
the
inlet
to
each
catalyst
bed,
then
we
would
expect
facilities
to
average
the
measurements
from
each
thermocouple
to
provide
a
representative
catalyst
bed
inlet
temperature
for
each
individual
catalyst
bed.

Finally,
the
final
rule
also
includes
an
option
(
in
lieu
of
monitoring
oxidizer
temperature)
for
monitoring
and
maintaining
the
oxidizer
outlet
THC
concentration
at
or
below
the
operating
limit
established
during
the
performance
test.
Use
of
the
THC
monitoring
option
would
eliminate
the
concerns
regarding
establishing
and
monitoring
oxidizer
operating
temperatures
(
in
effect,
it
provides
facilities
complete
flexibility
in
operation
of
the
control
device,
as
long
as
the
THC
outlet
concentration
remains
below
the
operating
limit).

Comment:
One
commenter
recommended
that
we
require
sampling
and
testing
of
the
catalyst
activity
level
for
RCO.

The
commenter
stated
that
the
proposed
requirement
to
monitor
inlet
pressure
may
not
be
sufficient
to
detect
190
catalyst
problems
such
as
poisoning,
blinding,
or
degradation.

Response:
We
agree
with
the
commenter
that
a
catalyst
activity
level
check
is
needed
because
catalyst
beds
can
become
poisoned
and
rendered
ineffective.
An
activity
level
check
can
consist
of
passing
an
organic
compound
of
known
concentration
through
a
sample
of
the
catalyst,
measuring
the
percentage
reduction
of
the
compound
across
the
catalyst
sample,
and
comparing
that
percentage
reduction
to
the
percentage
reduction
for
a
fresh
sample
of
the
same
type
of
catalyst.
Generally,
the
PCWP
facility
would
remove
a
representative
sample
of
the
catalyst
from
the
catalytic
oxidizer
bed
and
then
ship
the
sample
to
a
testing
company
for
analysis
of
its
ability
to
oxidize
organic
compounds
(
e.
g.,
by
a
flame
ionization
detector).

In
response
to
this
comment,
we
added
to
the
final
rule
a
requirement
for
facilities
with
catalytic
oxidizers
to
perform
an
annual
catalyst
activity
check
on
a
representative
sample
of
the
catalyst
and
to
take
any
necessary
corrective
action
to
ensure
that
the
catalyst
is
performing
within
its
design
range.
Corrective
actions
may
include
washing
or
baking
out
the
catalytic
media,

conducting
an
emissions
test
to
ensure
the
catalytic
media
is
resulting
in
the
desired
emissions
reductions,
or
partial
or
full
media
replacement.
Catalysts
are
designed
to
have
191
an
activity
range
over
which
they
will
reduce
emissions
to
the
desired
levels.
Therefore,
the
final
rule
specifies
that
corrective
action
is
needed
only
when
the
catalyst
activity
is
outside
of
this
range.
It
is
not
our
intention
for
facilities
to
replace
catalyst
if
the
catalytic
media
is
not
performing
at
the
maximum
level
it
achieved
when
the
catalyst
was
new.
Also,
the
final
rule
specifies
that
the
catalyst
activity
check
must
be
done
on
a
representative
sample
of
the
catalyst
to
ensure
that
facilities
that
may
have
recently
conducted
a
partial
media
replacement
do
not
sample
only
the
fresh
catalytic
media
for
the
catalyst
activity
check.

Comment:
Several
commenters
stated
that
the
proposed
operating
requirements
for
pressure
drop
across
the
biofilter
bed
should
be
removed
from
the
final
PCWP
rule.

The
commenters
contended
that
pressure
drop
is
a
good
parameter
to
monitor
voluntarily
because
it
indicates
the
permeability
and
age
of
the
biofilter
bed,
helping
to
determine
maintenance
and
replacement
needs;
however,
it
is
not
an
indicator
of
destruction
efficiency.
The
commenters
noted
that,
because
of
normal
wear
and
tear,
the
pressure
drop
gradually
increases
over
the
2­
to
5­
year
life
span
of
the
biofilter,
so
it
would
not
be
possible
to
maintain
a
constant
operating
pressure.
The
commenters
further
noted
that
the
supporting
materials
in
the
project
docket
did
not
192
provide
any
information
or
data
that
would
support
the
idea
that
pressure
drop
is
an
indication
of
HAP
destruction
efficiency,
but
only
indicated
that
pressure
drop
was
an
indication
of
the
age
of
the
biofilter.
For
these
reasons,

the
commenters
argued
that
setting
an
absolute
limit
on
pressure
drop
was
inappropriate.

The
commenters
also
requested
that
the
proposed
requirements
to
monitor
the
pH
of
the
biofilter
bed
effluent
be
removed
from
the
final
PCWP
rule.
The
commenters
noted
that
pH
is
a
good
parameter
to
monitor
voluntarily
because
it
indicates
the
environmental
conditions
inside
the
biofilter
bed
and
can
indicate
the
presence
of
organic
acids
and
THC
decomposition
products,
but
it
is
not
a
reliable
indicator
of
destruction
efficiency.
According
to
the
commenters,
small
fluctuations
of
pH
are
expected
and
have
little
effect
on
the
biofilter
performance;
therefore,
the
narrow
range
of
pH
values
that
would
be
established
as
an
operating
range
by
the
initial
compliance
tests
should
not
be
used
alone
to
determine
biofilter
performance.
The
commenters
also
noted
some
problems
associated
with
continuous
measurement
of
pH.
According
to
the
commenters,

some
biofilter
units
operate
with
periodic
irrigation
of
the
bed,
such
that
the
effluent
flow
is
not
constant
and
continuous
monitoring
is
not
possible.
The
commenters
also
pointed
to
an
NCASI
survey
that
confirmed
that
continuous
pH
193
monitoring
would
be
impractical
for
the
facilities
surveyed.

The
commenters
stated
that,
because
none
of
the
PCWP
facilities
surveyed
could
find
a
link
between
pH
alone
and
biofilter
performance,
none
of
those
facilities
currently
have
continuous
pH
monitors
on
their
biofilters.

In
addition,
several
commenters
requested
changes
to
the
proposed
requirement
to
monitor
the
inlet
temperature
of
the
biofilter.
These
commenters
agreed
that
temperature
is
a
parameter
that
should
be
monitored
for
biofilters,
but
argued
that
the
location
of
the
temperature
monitor
should
be
changed
from
the
biofilter
inlet
to
the
biofilter
bed
or
biofilter
outlet.
The
commenters
noted
that
the
biofilter
bed
temperature
has
the
greatest
impact
on
biological
activity.
According
to
the
commenters,
the
biofilter
inlet
temperature
is
not
a
good
indicator
of
bed
temperature
and
can
change
very
rapidly
depending
upon
the
operating
rate
of
the
press,
the
humidity,
and
the
ambient
temperature.

Response:
We
agree
with
the
commenters
that
increases
in
pressure
drop
will
occur
over
time
and
will
not
necessarily
equate
to
a
reduction
in
control
efficiency,

making
an
absolute
limit
on
pressure
drop
ineffective
in
demonstrating
continuous
compliance.
Therefore,
we
have
not
included
the
requirement
to
monitor
pressure
drop
in
the
operating
requirements
for
biofilters
in
the
final
PCWP
rule.
We
have
also
removed
the
requirement
to
monitor
pH
194
from
the
final
rule.
Although
pH
is
an
indicator
of
the
health
of
the
microbial
population
inside
the
biofilter,
we
agree
with
the
commenters
that
including
continuous
pH
monitoring
as
an
operating
requirement
for
biofilters
may
not
be
appropriate.

We
also
agree
with
the
commenters
that
the
biofilter
bed
temperature
has
the
greatest
impact
on
biological
activity
and
that
the
location
for
monitoring
the
biofilter
temperature
should
be
changed.
We
did
not
propose
monitoring
of
biofilter
bed
temperature
because
we
thought
that
monitoring
of
biofilter
inlet
temperature
would
be
simpler
because
only
one
thermocouple
would
be
required.

The
temperature
inside
the
biofilter
bed
can
change
in
different
areas
of
the
bed,
and
therefore,
depending
on
the
biofilter,
multiple
thermocouples
may
be
necessary
to
get
an
accurate
picture
of
the
temperature
conditions
inside
the
biofilter
bed.
Prior
to
proposal
we
rejected
the
idea
of
monitoring
the
biofilter
exhaust
temperature
because
temperature
measured
at
this
location
can
be
affected
by
ambient
temperature
(
especially
for
biofilters
with
short
stacks)
more
than
the
temperature
inside
the
biofilter
bed.

We
now
conclude
that
there
is
no
better,
more
representative
way
to
monitor
the
temperature
to
which
the
biofilter
microbial
population
is
exposed
than
to
directly
monitor
the
temperature
of
the
biofilter
bed.
According
to
our
MACT
195
survey
data,
most
facilities
with
biofilters
are
already
monitoring
biofilter
bed
temperature.
Therefore,
the
final
rule
requires
continuous
monitoring
of
the
temperature
inside
the
biofilter
bed.

The
proposed
rule
would
have
allowed
facilities
to
specify
their
own
monitoring
methods,
monitoring
frequencies,
and
averaging
times
for
the
proposed
biofilter
operating
parameters
(
i.
e.,
inlet
temperature,
effluent
pH,

and
pressure
drop).
However,
monitoring
of
temperature
is
not
as
subjective
as
monitoring
biofilter
effluent
pH
and
pressure
drop;
therefore,
as
an
outgrowth
of
our
decision
to
not
require
monitoring
of
biofilter
effluent
pH
and
pressure
drop,
the
final
rule
specifies
the
monitoring
method,

frequency,
and
averaging
time
for
biofilter
bed
temperature
monitoring.
The
final
rule
requires
that
each
thermocouple
be
placed
in
a
representative
location
and
clarifies
that
multiple
thermocouples
may
be
used
in
different
locations
within
the
biofilter
bed.
The
temperature
data
(
i.
e.,

average
temperature
across
all
the
thermocouples
located
in
the
biofilter
bed
if
multiple
thermocouples
are
used)
must
be
monitored
continuously
and
reduced
to
a
24­
hour
block
average.
A
24­
hour
block
average
was
selected
for
biofilter
temperature
monitoring
because
we
recognize
that
there
may
be
some
diurnal
variation
in
temperature.
Facilities
wishing
to
reflect
a
diurnal
temperature
variation
when
196
establishing
their
biofilter
temperature
may
wish
to
perform
some
test
runs
during
peak
daily
temperatures
and
other
test
runs
early
in
the
morning,
when
temperatures
are
at
their
lowest.

Facilities
may
choose
to
observe
parameters
other
than
biofilter
bed
temperature,
but
will
not
be
required
to
record
or
control
them
for
the
final
PCWP
rule.
We
feel
that
many
factors
can
affect
biofilter
performance,
either
alone
(
e.
g.,
a
media
change)
or
in
concert
with
one
another
(
e.
g.,
a
loss
of
water
flow
results
in
a
sharp
change
in
temperature
and
pH).
The
factors
that
have
the
greatest
effect
on
biofilter
performance
are
likely
to
be
sitespecific
However,
based
on
the
comments
we
have
received,

we
conclude
that
extensive
biofilter
parameter
monitoring
is
not
the
best
method
for
ensuring
continuous
compliance.
To
promote
enforceability
of
the
final
PCWP
rule,
we
have
added
a
requirement
to
perform
periodic
testing
of
biofilters.

The
final
rule
requires
facilities
to
conduct
a
repeat
test
at
least
every
2
years
and
within
180
days
after
a
portion
of
the
biofilter
bed
is
replaced
with
a
new
type
of
media
or
more
than
50
percent
(
by
volume)
of
the
biofilter
media
is
replaced
with
the
same
type
of
media.
Each
repeat
test
must
be
conducted
within
2
years
of
the
previous
test
(
e.
g.,
2
years
after
the
initial
compliance
test,
or
2
years
after
the
test
following
a
media
change).
We
are
requiring
repeat
197
testing
after
a
partial
or
wholesale
change
to
another
media
type
(
considered
a
modification
of
the
biofilter)
because
such
a
modification
can
impact
the
performance
of
the
biofilter.
Facilities
that
replace
biofilter
media
with
a
new
type
of
media
(
e.
g,
bark
versus
synthetic
media)
must
also
re­
establish
the
limits
of
the
biofilter
bed
temperature
range.
We
feel
that
substantial
replacement
of
the
biofilter
media
(
e.
g.,
replacement
of
more
than
50
percent
of
the
media)
with
the
same
type
of
media
may
affect
short­
term
performance
of
the
biofilter
while
the
replacement
media
becomes
acclimated,
and
therefore,
the
final
rule
requires
a
repeat
performance
test
following
this
type
of
media
replacement.
However,
PCWP
facilities
that
replace
biofilter
media
with
the
same
type
of
media
are
not
required
to
re­
establish
the
biofilter
bed
temperature
range.
In
the
case
of
same­
media
replacements,
we
feel
it
is
appropriate
for
PCWP
facilities
to
be
able
to
use
data
from
previous
performance
tests
to
establish
the
limits
of
the
temperature
range.
During
repeat
testing
following
replacement
with
the
same
type
of
media,
facilities
can
verify
that
the
biofilter
remains
within
the
temperature
range
established
previously
or
establish
a
new
compliant
temperature
range.
Facilities
using
a
THC
CEMS
that
choose
to
comply
with
the
THC
compliance
options
(
i.
e.,
90
percent
reduction
in
THC
or
outlet
THC
concentration
less
than
or
198
equal
to
20
ppmvd)
may
use
the
data
from
their
CEMS
in
lieu
of
conducting
repeat
performance
testing.

Comment:
Several
commenters
requested
that
the
final
rule
allow
new
biofilters
a
longer
period
than
180
days
to
establish
operating
parameter
levels.
These
commenters
suggested
a
1­
year
period,
because
that
would
be
long
enough
to
observe
the
full
seasonal
variation
in
parameters
and
find
the
true
operating
maxima
and
minima.

Response:
We
disagree
that
more
than
180
days
is
necessary
to
establish
operating
parameter
limits
for
biofilters.
As
mentioned
previously,
we
have
eliminated
the
proposed
requirement
to
establish
operating
limits
for
pH
and
pressure
drop.
Today's
final
rule
contains
two
options
for
biofilter
operating
parameter
limits:
biofilter
bed
temperature
range
and
outlet
THC
concentration.
While
allowing
1
year
to
establish
the
biofilter
bed
temperature
operating
range
is
reasonable
due
to
seasonal
temperature
variations,
1
year
is
not
necessary
for
establishing
an
outlet
THC
concentration
limit.
Furthermore,
the
final
rule
already
allows
facilities
to
expand
their
operating
ranges
(
see
§
63.2262(
m)(
3))
through
additional
emissions
testing.

The
compliance
date
for
existing
facilities
is
3
years
after
promulgation
of
the
final
PCWP
rule,
and
existing
facilities
are
allowed
180
days
following
the
compliance
date
to
conduct
performance
testing
and
establish
the
199
operating
parameter
limits.
If
there
is
concern
that
180
days
is
not
long
enough
for
a
new
biofilter
installation
to
operate
under
the
full
range
of
biofilter
bed
temperatures,

then
existing
facilities
should
begin
operation
of
their
biofilter
well
before
the
compliance
date
(
e.
g.,
180
days
prior
to
the
compliance
date
if
1
year
is
needed).

Facilities
also
have
the
option
of
testing
their
biofilter
prior
to
the
compliance
date
to
establish
one
extreme
of
their
biofilter
bed
temperature
range.
The
compliance
date
for
new
PCWP
facilities
is
the
effective
date
of
the
rule
(
if
startup
is
before
the
effective
date)
or
upon
initial
startup
(
if
the
initial
startup
is
after
the
effective
date
of
the
rule),
and
biofilters
installed
at
new
PCWP
facilities
would
have
up
to
180
days
following
the
compliance
date
to
establish
the
operating
parameter
limits.

To
address
situations
where
a
new
biofilter
is
installed
at
an
existing
facility
more
than
180
days
after
the
compliance
date
(
e.
g.,
to
replace
an
existing
RTO),
we
have
included
section
§
63.2262(
m)(
2)
to
the
final
PCWP
rule,
which
allows
existing
sources
that
install
new
biofilters
up
to
180
days
following
the
initial
startup
date
of
the
biofilter
to
establish
the
operating
parameter
limits.
Thus,
new
biofilter
installations
are
given
time
for
establishment
of
operating
parameter
limits
regardless
of
where
they
are
installed
at
new
or
existing
sources.
200
Comment:
Multiple
commenters
supported
the
option
to
continuously
monitor
THC
at
control
device
outlets
to
demonstrate
compliance,
but
suggested
that
either
the
procedure
for
determining
the
operating
limits
or
the
length
of
the
averaging
periods
be
altered.
The
commenters
stated
that
THC
concentration
at
a
control
device
outlet
is
not
a
parameter
that
can
be
easily
adjusted
by
operators
over
short
periods
of
time.
The
commenters
stated
that
3
hours
is
not
a
long
enough
block
to
avoid
deviations
from
compliance
given
the
variability
of
the
process.
The
commenters
provided
an
analysis
of
THC
data
from
a
biofilter
outlet
that
showed
multiple
deviations
occurring
over
a
two
month
period
when
a
3­
hour
block
average
was
used
and
few
to
zero
deviations
when
a
24­
hour
or
7­
day
block
average
was
used
for
the
operating
limits.
The
commenters
stated
that
because
HAP
destruction
efficiency
of
biofilters
does
not
vary
much
with
time,
the
longer
block
average
would
not
be
environmentally
harmful.

Response:
While
THC
emissions
at
the
outlet
of
a
biofilter
may
vary,
the
THC
emissions
at
the
outlet
of
a
thermal
or
catalytic
oxidizer
should
not
vary
greatly.

Although,
as
stated
by
the
commenters,
the
HAP
destruction
efficiency
of
biofilters
is
not
subject
to
large
short­
term
variations,
the
same
is
not
true
for
thermal
and
catalytic
oxidizers
(
e.
g.,
a
sudden
significant
decrease
in
201
temperature
could
result
in
a
sudden
decrease
in
HAP
reduction).
Therefore,
we
feel
it
is
appropriate
to
maintain
the
3­
hour
block
averaging
requirement
for
THC
monitoring
for
thermal
and
catalytic
oxidizers.
However,
we
have
expanded
the
THC
averaging
requirement
for
biofilters
to
a
24­
hour
block
average
to
provide
more
flexibility.
The
THC
operating
limit
for
biofilters
would
be
established
as
the
maximum
of
three
15­
minute
recorded
readings
during
emissions
testing.
We
also
note
the
continuous
monitoring
of
THC
is
not
required
for
all
APCD,
but
is
an
alternative
to
continuous
monitoring
of
temperature.
Furthermore,

facilities
can
conduct
multiple
performance
tests
at
different
operating
conditions
to
increase
their
maximum
THC
concentration
operating
limit.

6.
Selection
of
Monitoring
Requirements
for
Uncontrolled
Process
Units
Comment:
Several
commenters
recommended
that
we
change
the
title
of
proposed
§
63.2262
(
n)
(
How
do
I
conduct
performance
tests
and
establish
operating
requirements?
­

Establishing
uncontrolled
process
unit
operating
requirements)
to
"
Establishing
operating
requirements
for
production­
based
compliance
option
process
units"
for
the
final
rule.
The
commenters
stated
that
the
proposed
title
implied
that
no
controls
of
any
kind
are
being
applied
to
these
process
units,
when
in
fact
facilities
may
be
using
P2
202
techniques
to
reduce
emissions.
The
commenters
also
objected
to
wording
within
the
proposed
section
that
suggests
that
temperature
is
the
only
parameter
affecting
HAP
emissions
from
the
process
units.
The
commenters
suggested
that
the
requirements
be
revised
in
the
final
rule
to
give
sources
more
flexibility
in
identifying
and
documenting
those
process
unit
operating
parameters
that
are
critical
to
maintaining
compliance
with
the
PBCO
limits.

Response:
At
proposal,
our
intention
was
to
establish
operating
requirements
for
those
process
units
complying
with
rule
requirements
without
the
use
of
an
APCD.
There
are
two
situations
in
the
PCWP
rule
as
proposed
where
process
units
may
not
have
an
add­
on
control
device:
(
1)

when
process
units
meet
the
PBCO,
or
(
2)
when
process
units
used
to
generate
emissions
averaging
debits
do
not
have
an
add­
on
APCD
that
partially
controls
emissions.
To
clarify
this
for
the
final
rule
and
to
address
the
commenters'

concern
regarding
applicability
of
§
63.2262(
n),
we
changed
the
title
of
the
section
to
"
Establishing
operating
requirements
for
process
units
meeting
compliance
options
without
a
control
device."

We
agree
with
the
commenters
that
temperature
alone
is
not
necessarily
the
sole
factor
affecting
HAP
emissions
from
some
process
units.
A
variety
of
factors
can
affect
HAP
emissions,
and
the
controlling
parameter
for
one
process
203
unit
may
be
different
than
the
controlling
parameter
for
another
process
unit.
Therefore,
the
final
rule
gives
sources
more
flexibility
in
selecting
and
establishing
operating
limits
for
process
units
without
add­
on
controls.

The
final
rule
requires
facilities
to
identify
and
document
the
operating
parameter(
s)
that
affect
HAP
emissions
from
the
process
unit
and
to
establish
appropriate
monitoring
methods
and
monitoring
frequencies.
We
recognize
that
it
is
not
practical
to
continuously
monitor
every
process­

unitspecific
factor
that
could
affect
uncontrolled
emissions
(
e.
g.,
there
is
no
way
to
monitor
and
determine
a
3­
hour
block
average
of
wood
species
mix
for
a
particleboard
plant).
However,
some
parameters
are
suitable
for
continuous
monitoring
(
e.
g.,
process
operating
temperature,

furnish
moisture
content)
and
are
already
monitored
as
part
of
normal
operation
but
not
for
compliance
purposes.
We
feel
that
daily
records
of
most
parameters
would
be
sufficient
to
ensure
ongoing
compliance
(
e.
g.,
daily
average
process
operating
temperature,
furnish
moisture,
resin
type,

wood
species
mix)
if
the
parameters
do
not
deviate
from
the
ranges
for
these
parameters
during
the
initial
compliance
test.
Therefore,
in
the
final
PCWP
rule,
we
have
replaced
the
proposed
3­
hour
block
average
temperature
monitoring
requirements
for
process
units
without
control
devices
with
a
requirement
to
maintain,
on
a
daily
basis,
the
process
204
unit
operating
parameter(
s)
within
the
ranges
established
during
the
performance
test.
This
gives
facilities
the
flexibility
to
decide
which
parameters
they
will
monitor
and
control,
while
providing
enforcement
personnel
with
records
that
can
be
used
to
assess
and
compare
the
day­
to­
day
operation
of
the
process
unit
to
the
controlling
operating
parameters.
Facilities
are
also
allowed
to
decide
for
each
parameter
the
appropriate
monitoring
methods,
monitoring
frequencies,
and
averaging
times
(
not
to
exceed
24
hours
for
continuously
monitored
parameters
such
as
temperature
and
wood
furnish
moisture).
Also,
to
ensure
that
the
HAP
emissions
measured
during
the
compliance
tests
are
representative
of
actual
emissions,
the
final
rule
requires
testing
at
representative
operating
conditions,
as
defined
in
the
rule.

7.
Data
Collection
and
Handling
Comment:
Several
commenters
requested
clarifications
and
changes
to
the
proposed
requirements
related
to
data
collection
and
handling
for
CPMS.
The
commenters
stated
that
the
requirement
that
a
valid
hour
of
data
must
include
at
least
three
equally
spaced
data
values
for
that
hour
is
ambiguous
and
should
be
revised.
The
commenters
recommended
that
the
final
rule
require
facilities
to
average
at
least
three
data
points
taken
at
constant
intervals,
provided
the
interval
is
less
than
or
equal
to
15
minutes.
The
205
commenters
further
noted
that
a
better
approach
would
be
to
drop
the
concept
of
an
hourly
average
altogether
and
simply
calculate
the
block
average
as
the
average
of
all
evenly
spaced
measurements
in
the
block
period
with
a
maximum
measurement
interval
of
15
minutes.
The
commenters
also
noted
that
the
proposed
rule
did
not
specify
how
to
calculate
the
3­
hour
block
average
when
one
or
more
of
the
individual
hours
does
not
contain
at
least
three
valid
data
values.

Commenters
also
requested
that
the
final
rule
consolidate
and
clarify
the
requirements
in
proposed
§
§
63.2268
and
63.2270
regarding
data
that
should
be
excluded
from
block
averages.
The
commenters
recommended
that
the
final
rule
explicitly
state
that
any
monitoring
data
taken
during
periods
when
emission
control
equipment
are
not
accepting
emissions
from
the
production
processes
should
be
excluded
from
hourly
or
block
averages.
The
commenters
also
noted
inconsistencies
in
the
proposed
rule
language
that
seemed
to
imply
that
data
collected
during
production
downtime
and
SSM
events
would
be
included
in
the
hourly
averages
but
not
in
the
block
averages.
The
commenters
stated
that,
because
SSM
events
occur
when
the
process
is
not
in
operation,
there
is
no
need
to
collect
data
from
these
periods.

Response:
We
agree
with
the
commenters
that
the
206
proposed
rule
language
regarding
acceptable
data
and
data
averaging
was
somewhat
ambiguous
and
have
revised
the
language
accordingly.
Following
the
commenters'

recommendation,
we
removed
the
concept
of
an
hourly
average
from
the
final
rule
to
allow
block
averages
to
be
calculated
as
the
average
of
all
evenly
spaced
measurements
in
the
3­

hour
or
24­
hour
block
period
with
a
maximum
measurement
interval
of
15
minutes.
In
place
of
the
requirement
for
a
valid
hourly
average
to
contain
at
least
three
equally
spaced
data
values
for
that
hour,
we
added
a
minimum
data
availability
requirement.
The
minimum
data
availability
requirement
specifies
that
to
calculate
data
averages
for
each
3­
hour
or
24­
hour
averaging
period,
you
must
have
at
least
75
percent
of
the
required
recorded
readings
for
that
period
using
only
recorded
readings
that
are
based
on
valid
data.
The
minimum
data
availability
requirement
appears
in
§
63.2270(
f)
of
today's
final
rule.
To
clarify
what
constitutes
valid
data
and
how
to
calculate
block
averages,

we
rearranged
proposed
§
§
63.2268
and
63.2270.
We
moved
proposed
§
63.2268(
a)(
3)
and
(
4)
to
final
§
63.2270
(
now
§
63.2270(
d)
and
(
e))
of
today's
final
rule.
Rather
than
repeating
which
data
should
be
excluded
from
data
averages
in
§
63.2270(
d)
and
(
e),
these
new
sections
now
refer
to
§
63.2270(
b)
and
(
c)
when
discussing
data
that
should
not
be
included
in
data
averages.
We
also
added
data
recorded
207
during
periods
of
SSM
to
the
list
of
data
that
should
be
excluded
from
data
averages
in
§
63.2270.
We
feel
these
changes
to
the
structure
and
wording
of
the
rule
should
fully
address
the
commenters'
concerns.

Comment:
Several
commenters
noted
that
the
proposed
PCWP
rule
does
not
provide
any
alternatives
to
the
definition
of
a
1­
hour
period
found
in
the
MACT
general
provisions
(
40
CFR
63.2),
which
states
that
a
1­
hour
period
is
any
60­
minute
period
commencing
on
the
hour.
These
commenters
requested
that
facilities
be
given
the
option
of
beginning
a
1­
hour
period
at
a
time
that
is
convenient
depending
on
shift
changes,
employee
duties
at
the
end
of
a
shift,
and
settings
on
the
systems
that
record
data.

Response:
We
agree
with
the
commenters
and
have
included
a
definition
of
1­
hour
period
in
today's
final
rule
that
omits
the
phrase
"
commencing
on
the
hour."

8.
Performance
Specifications
for
CPMS
Comment:
Several
commenters
requested
that
we
write
sections
of
the
final
rule
language
that
address
temperature
measurement.
The
commenters
stated
that
the
phrase
"
minimum
tolerance
of
0.75
percent,"
found
in
proposed
sections
63.2268(
b)(
2),
63.2268(
c)(
3),
and
63.2268(
e)(
2),
should
be
revised
to
read
"
accurate
within
0.75
percent
of
sensor
range."
The
commenters
argued
that,
because
tolerances
usually
refer
to
physical
dimensions,
this
revision
more
208
accurately
reflects
the
intent
of
the
final
PCWP
rule.

Commenters
also
recommended
that
the
sensitivity
for
chart
recorders
be
changed
from
a
sensitivity
in
the
minor
division
of
at
least
20
°
F
to
minor
divisions
of
not
more
than
20
°
F.
The
commenters
noted
that
the
wording
in
the
proposed
rule
means
that
minor
divisions
could
be
30
°
F
or
50
°
F,
but
assumed
that
we
probably
meant
that
20
°
F
is
the
largest
minor
division
that
a
facility
can
use,
and
therefore,
stated
that
the
suggested
revision
is
more
accurate.

Response:
We
agree
that
the
proposed
temperature
measurement
requirements
should
be
clarified.
In
today's
final
rule,
we
wrote
the
requirement
in
§
63.2269(
b)(
2)

(
formerly
proposed
§
63.2268(
b)(
2))
to
read
"
minimum
accuracy
of
0.75
percent
the
temperature
value."
We
eliminated
proposed
sections
§
§
63.2268(
c)
and
63.2268(
e)
from
the
final
rule
because
we
removed
the
requirements
for
monitoring
of
pressure
or
flow.
We
also
wrote
proposed
§
63.2268(
b)(
3)
to
state
that
"
If
a
chart
recorder
is
used,
it
must
have
a
sensitivity
with
minor
divisions
of
not
more
than
20oF."

Comment:
Several
commenters
requested
changes
to
the
proposed
work
practice
requirements
for
dry
rotary
dryers
and
veneer
redryers
related
to
moisture
monitoring.
The
commenters
noted
that
the
proposed
requirement
to
use
a
moisture
monitor
with
a
minimum
accuracy
of
1
percent
was
209
appropriate
for
rotary
dry
dryers
in
the
25
to
35
percent
moisture
content
range.
However,
the
commenters
stated
that
less
stringent
accuracy
requirements
should
be
included
for
veneer
redryers
to
better
correspond
with
current
practices
at
softwood
plywood
and
veneer
facilities.
Specifically,

the
commenters
requested
that
the
final
rule
revise
the
proposed
performance
specifications
for
moisture
monitors
for
veneer
redryers
to
allow
the
use
of
monitors
with
an
accuracy
of
±
3
percent
in
the
15
to
25
percent
moisture
range.
Several
commenters
also
requested
that
the
proposed
calibration
procedures
for
moisture
monitors
be
revised
in
the
final
rule
to
eliminate
grab
sampling
and
to
allow
facilities
to
follow
the
calibration
procedures
recommended
by
the
manufacturer.
The
commenters
argued
that
the
proposed
grab
sampling
procedure
is
impractical
and
that
obtaining
a
representative
grab
sample
would
be
difficult.

Response:
We
agree
with
the
commenters
that
the
proposed
moisture
monitoring
requirements
should
be
adjusted
in
the
final
rule
and
have
made
the
requested
changes
to
the
accuracy
requirements
for
moisture
monitors
used
with
rotary
dry
dryers
and
veneer
redryers.
We
have
also
adjusted
the
calibration
procedures
in
the
final
rule
to
eliminate
grab
sampling
and
to
allow
facilities
to
follow
the
manufacturer's
recommended
calibration
procedures
for
moisture
monitors.
210
I.
Routine
Control
Device
Maintenance
Exemption
(
RCDME)

Comment:
Several
commenters
requested
that
the
proposed
requirements
for
the
RCDME
be
modified
in
the
final
rule
to
give
PCWP
facilities
more
flexibility.
First,
the
commenters
requested
that
the
proposed
RCDME
allowances
(
expressed
as
a
percentage
of
the
process
unit
operating
hours)
be
increased.
The
commenters
argued
that
the
proposed
downtime
allowance
periods
are
too
short
to
allow
for
proper
maintenance.
The
commenters
noted
that
the
NCASI
survey
that
was
used
to
set
the
downtime
allowance
only
included
data
from
1999,
and
many
facilities
may
have
conducted
nonannual
maintenance
and
repairs
in
the
years
preceding
or
following
that
year.
According
to
the
commenters,
the
1999
survey
was
also
limited
in
that
the
majority
of
the
RTO
included
in
the
survey
were
less
than
5
years
old,
and
as
the
equipment
ages
over
a
lifetime
of
5
to
15
years,
performance
will
degrade
below
the
levels
seen
in
the
1999
survey.
Therefore,
the
commenters
suggested
that
we
reexamine
the
NCASI
downtime
data
and
use
the
79th
percentile
instead
of
the
50th
percentile
to
select
downtime
allowances
that
represent
the
time
needed
for
nonannual
events.

Response:
After
reviewing
our
previous
analysis
of
the
downtime
data,
we
maintain
that
the
percentage
downtime
we
proposed
(
3
percent
for
some
process
units
and
0.5
percent
211
for
others)
calculated
on
an
annual
basis
is
appropriate
for
the
final
PCWP
rule.
The
downtime
allowance
allowed
under
the
RCDME
is
intended
to
allow
facilities
limited
time
to
perform
routine
maintenance
on
their
APCD
without
shutting
down
the
process
units
being
controlled
by
the
APCD.
We
included
the
downtime
allowance
in
the
proposed
rule
because
we
recognize
that
frequent
maintenance
must
be
performed
to
combat
particulate
and
salt
buildup
in
some
RTO
and
RCO
for
PCWP
drying
processes.
The
downtime
allowance
is
not
intended
to
cover
every
APCD
maintenance
activity,
only
those
maintenance
activities
that
are
routine
(
e.
g.,

bakeouts,
washouts,
partial
or
full
media
replacements)
and
do
not
coincide
with
process
unit
shutdowns.
Most
APCD
maintenance
should
occur
during
process
unit
shutdowns;
the
RCDME
is
a
downtime
allowance
in
addition
to
the
APCD
maintenance
downtime
that
occurs
during
process
unit
shutdowns.
We
note
that
most
PCWP
plants
do
not
operate
8,760
hours
per
year
without
shutdowns.
For
example,
the
MACT
survey
responses
indicate
that
softwood
plywood
plants
operate
for
an
average
7,540
hours
per
year,
which
would
allow
1,220
hours
for
control
device
maintenance
without
the
RCDME.
Furthermore,
the
RCDME
is
allowed
in
addition
to
APCD
downtime
associated
with
SSM
events
covered
by
the
SSM
plan
(
e.
g.,
electrical
problems,
mechanical
problems,

utility
supply
problems,
and
pre­
filter
upsets).
For
these
212
reasons,
the
final
rule
retains
the
RCDME
allowances
included
in
the
proposed
rule.

Comment:
Several
commenters
objected
to
the
proposed
requirement
that
the
maintenance
be
scheduled
at
the
beginning
of
the
semiannual
period.
The
commenters
argued
that
scheduling
maintenance
activities
at
the
beginning
of
each
semiannual
period
is
neither
consistent
with
industry
practice
nor
practical.
The
commenters
noted
that
downtime
for
maintenance
is
scheduled
as
the
need
arises,
and
downtime
schedules
change
with
need
and
production
requirements.
The
commenters
stated
that
most
facilities
have
a
general
idea
of
when
they
intend
to
conduct
routine
maintenance
activities
and
will
schedule
those
activities
whenever
possible
to
coincide
with
process
downtime
as
it
approaches.
The
commenters
further
noted
that
the
proposed
PCWP
rule
does
not
clarify
what
would
happen
if
maintenance
were
necessary
before
the
scheduled
date.
Therefore,
the
commenters
concluded
that
deleting
the
requirement
to
set
the
maintenance
schedule
at
the
beginning
of
each
semiannual
period
would
eliminate
confusion
and
better
represent
industry
practice.

Response:
We
agree
with
the
commenters
and
have
removed
the
requirement
to
record
the
control
device
maintenance
schedule
for
the
semiannual
period
from
the
final
rule.
We
agree
that
the
proposed
requirement
would
be
impractical
213
because
process
unit
shutdowns
are
not
scheduled
semiannually.
Also,
the
SSM
provisions
do
not
require
scheduling
of
maintenance,
and
therefore,
requiring
scheduling
of
routine
maintenance
covered
under
the
RCDME
would
be
more
restrictive
than
the
requirements
for
SSM.
To
the
extent
possible,
APCD
maintenance
should
be
scheduled
at
the
same
time
as
process
unit
shutdowns.
Thus,
today's
final
rule
retains
the
requirement
that
startup
and
shutdown
of
emission
control
systems
must
be
scheduled
during
times
when
process
equipment
is
also
shut
down.

Comment:
Commenters
also
requested
that
the
proposed
RCDME
requirement
that
facilities
must
minimize
emissions
to
the
greatest
extent
possible
during
maintenance
periods
be
revised
to
require
that
facilities
make
reasonable
efforts
to
minimize
emissions
during
maintenance.
The
commenters
stated
that
this
revision
is
necessary
because
the
proposed
wording
could
be
interpreted
to
mean
that
sources
should
limit
production
or
shut
down
entirely
during
maintenance
periods,
which
is
contrary
to
the
intent
of
the
RCDME.

Response:
We
agree
with
the
commenters
and
have
modified
the
referenced
requirement
as
suggested
by
the
commenters.

J.
Startup,
Shutdown,
and
Malfunction
(
SSM)

Comment:
Several
commenters
noted
inconsistencies
between
the
proposed
rule
and
the
NESHAP
General
Provisions
214
(
40
CFR
part
63,
subpart
A)
and
requested
that
these
inconsistencies
be
resolved
by
making
the
final
PCWP
rule
consistent
with
the
latest
version
of
the
General
Provisions.

Response:
Approximately
1
month
prior
to
publication
of
the
proposed
PCWP
rule,
we
published
proposed
amendments
to
the
NESHAP
General
Provisions
concerning
SSM
procedures
(
67
FR
72875,
December
9,
2002)
and
promulgated
them
in
May
2003
(
68
FR
32585,
May
30,
2003).
Due
to
the
timing
of
the
these
rulemakings,
the
proposed
PCWP
rule
language
did
not
reflect
our
most
recent
decisions
regarding
SSM.
To
avoid
confusion
and
promote
consistency,
we
have
written
the
final
rule
to
reference
the
NESHAP
General
Provisions
directly,
where
applicable,
and
to
be
more
consistent
with
other
recently
promulgated
MACT
standards.
Although
the
amendments
to
the
NESHAP
General
Provisions
regarding
SSM
plans
are
currently
involved
in
litigation,
the
rule
requirements
promulgated
on
May
30,
2003,
apply
to
the
final
PCWP
NESHAP
unless
and
until
we
promulgate
another
revision.
In
response
to
suggestions
made
by
commenters,
we
also
consolidated
several
sections
to
clarify
the
requirements
related
to
SSM
and
to
eliminate
redundancies
in
the
final
rule.
Specifically,
we
combined
proposed
§
63.2250(
d)
with
proposed
§
63.2250(
a)
and
revised
the
resulting
§
63.2250(
a)
to
clarify
that
the
SSM
periods
mentioned
in
proposed
§
63.2250(
a)
apply
to
both
process
units
and
control
devices
and
to
clarify
when
the
compliance
options,
operating
requirements,
and
work
practice
requirements
do
and
do
not
apply.
We
also
removed
proposed
§
63.2250(
e)
from
the
final
rule
because
it
was
a
duplication
of
proposed
§
63.2251(
e)
regarding
control
device
maintenance
schedules.
In
addition,
we
removed
proposed
§
63.2250(
f)
related
to
RCO
catalyst
maintenance
because
this
section
was
misplaced
and
is
not
consistent
with
the
RCO
monitoring
requirements
in
today's
final
rule.

K.
Risk­
Based
Approaches
1.
General
comments
Risk­
based
approaches
Comment:
Numerous
commenters
encouraged
EPA
to
exercise
all
of
the
flexibility
within
its
authority
and
offer
the
widest
possible
array
of
options
so
that
facilities
that
pose
little
risk
to
public
health
or
the
environment
would
not
be
forced
to
add
expensive
and
unproductive
control
equipment
which
would
weaken
them
financially
or
cause
them
to
close.
Commenters
specifically
recommended
that
EPA
incorporate
risk­
based
options
similar
to
all
three
industry
white
papers,
which
would
exclude
facilities
that
pose
no
significant
risk
to
public
health
or
the
environment.
(
As
an
alternative,
one
commenter
recommended
that
EPA
at
least
incorporate
the
concentration­
based
de
minimis
applicability
exemption.)

Commenters
stated
that
inclusion
of
risk
provisions
has
216
the
potential
to
achieve
overall
environmentally
superior
results
in
a
cost­
effective
manner,
particularly
in
cases
where
criteria
pollutants
from
control
devices
(
i.
e.,

incinerators)
may
result
in
greater
impacts
that
the
HAP
emissions
that
they
control.
According
to
a
life
cycle
analysis
conducted
by
one
commenter,
incinerators
used
to
limit
HAP
emissions
from
low­
risk
wood
products
facilities
would
create
more
harm
than
good
through
their
consumption
of
electricity
and
natural
gas.
The
commenter
noted
that
incinerators
emit
carbon
monoxide
(
CO2)
and
criteria
pollutants,
which
could
affect
a
State's
ability
to
meet
the
National
Ambient
Air
Quality
Standards
(
NAAQS)
attainment
requirements
under
the
CAA.
In
particular,
the
commenter
referred
to
EPA's
projection
that
adoption
of
MACT
floor
level
controls
would
result
in
increased
emissions
of
NOx,
a
precursor
to
ozone
and
PM.
According
to
the
commenter,
the
proposed
rule
(
without
risk
provisions)
would
work
against
the
industry's
voluntary
commitment,
in
response
to
President
Bush's
initiative,
to
reduce
the
emissions
of
greenhouse
gases
by
12
percent
over
the
next
10
years.
The
commenter
noted
that
the
costly
mandatory
controls
proposed,

coupled
with
stiff
foreign
competition
and
regulatory
mandates
under
other
MACT
rules,
would
also
create
significant
financial
hardship
across
all
sectors
of
the
industry
and
jeopardize
the
commercial
viability
of
numerous
217
facilities,
many
of
which
are
the
principal
employer
in
the
small,
rural
towns
in
which
they
are
located.
The
projected
costs
for
the
proposed
rule
are
enormous
amounts
of
money
for
an
industry
already
operating
at
the
margin
in
a
depressed
economic
climate.
Noting
EPA's
prediction
that
the
proposed
rule
would
avert
0.07
cases
of
cancer
per
year,

or
one
case
every
14
years,
the
commenter
stated
that
this
would
yield
a
cost­
effectiveness
of
$
2.4
billion
per
cancer
case
averted.
The
commenter
compared
the
cost
per
premature
death
averted
for
several
rules
and
found
the
PCWP
rule
as
proposed
to
be
one
of
the
more
costly.
The
commenter
concluded
that,
in
its
proposed
form,
the
rule
would
impose
hundreds
of
millions
of
dollars
ofsignificant
additional
cost
with
virtually
no
gain
to
either
the
environment
or
the
health.
The
commenter
stated
that
the
proposed
rule
would
be
one
of
the
most
cost­
ineffective
rules
ever
promulgated
by
EPA.
According
to
the
commenter,
the
overwhelming
advantage
of
the
risk­
based
approach
is
that
it
avoids
imposing
high
costs
on
low­
risk
facilities,
where
there
is
little
or
no
benefit
to
be
gained
for
either
the
environment
or
the
public
interest.
The
commenter
stated
that
the
wood
products
industry
as
a
whole
poses
a
small­
to­
insignificant
risk
to
human
health
and
the
environment.

The
commenter
stated
that
the
final
rule
should
include
reasonable
risk­
based
mechanisms
to
allow
facilities
posing
218
no
significant
risk
to
limit
their
emissions
below
levels
of
concern
without
having
to
install
incinerator
controls.
The
commenter
stated
that
facilities
wishing
to
take
advantage
of
the
risk­
based
exemption
would
take
a
federally­
enforceable
permit
limit
that
would
guarantee
that
their
emissions
remain
below
the
risk­
based
emission
standard.
This
would
constitute
an
emission
limitation,

within
the
statutory
definition
of
the
term,
and
it
would
allow
facilities
to
forego
the
installation
of
incinerators
where
they
are
not
warranted
by
public
health
and
environmental
considerations,
the
commenter
claimed.

Some
commenters
argued
that
the
risk­
based
options
are
legally
justified,
protective
of
human
health
and
the
environment,
and
economically
sensible.
These
commenters
stated
that
the
risk­
based
options
are
supported
under
the
CAA,
through
EPA's
authority
under
sections
112(
d)(
4)
and
112(
c)(
9)
to
set
emission
standards
other
than
MACT
for
certain
low­
risk
facilities
and
delist
technology­
defined
low­
risk
subcategories,
respectively,
and
through
what
they
claimed
is
EPA's
inherent
de
minimis
authority
to
avoid
undertaking
regulatory
action
in
the
absence
of
meaningful
risk.
One
commenter
pointed
out
that,
by
meeting
the
stringent
health
benchmarks
necessary
to
qualify
for
the
risk­
based
compliance
approaches,
facilities
already
would
have
satisfied
the
residual
risk
provisions
8
years
ahead
of
219
the
statutory
requirements
set
forth
in
section
112(
f)
of
the
CAA.

Two
commenters
believed
that
the
risk­
based
approach
would
particularly
benefit
small
mills
located
in
rural
areas
with
timber­
dependent
economies.
One
commenter
stated
that,
by
offering
manufacturers
an
opportunity
to
apply
for
subcategorization
on
a
site­
specific
basis,
facilities
that
are
remotely
located,
or
which
were
originally
planned
and
sited
with
thorough
consideration
of
airshed
impacts,
would
not
be
unduly
burdened
with
MACT
requirements
which
yield
little
or
no
public
health
benefits.

Some
commenters
argued
that
such
low­
risk
facilities
should
not
be
burdened
with
the
requirements
of
MACT.
One
commenter
noted
that
the
regulatory
framework
exists
within
their
State
to
implement
a
risk­
based
approach.
Another
commenter
agreed
with
the
concept
of
a
risk­
based
approach
but
stated
that
it
would
not
be
appropriate
for
State
and
local
programs
to
determine
which
facilities
should
be
exempted
from
MACT.
Another
commenter
suggested
that
exemptions
be
provided
on
a
case­
by­
case
basis
to
individual
facilities
that
are
able
to
demonstrate
that
they
pose
no
significant
risk
to
public
health
or
the
environment.

Several
commenters
opposed
the
risk­
based
exemptions.

Two
commenters
stated
that
the
use
of
risk­
based
concepts
to
evade
MACT
applicability
is
contrary
to
the
intent
of
the
220
CAA
and
is
based
on
a
flawed
interpretation
of
section
112(
d)(
4)
written
by
an
industry
subject
to
regulation.
One
commenter
added
that
the
CAA
requires
a
technology­
based
floor
level
of
control
and
does
not
provide
exclusions
for
risk
or
secondary
impacts
in
applying
the
MACT
floor.
The
other
commenter
was
particularly
concerned
about
industry's
unprecedented
proposal
to
include
de
minimis
exemptions
and
cost
in
the
MACT
standard
process.
The
commenter
stated
that
including
case­
by­
case
risk­
based
exemptions
would
jeopardize
the
effectiveness
of
the
national
air
toxics
program
to
adequately
protect
public
health
and
the
environment
and
to
establish
a
level
playing
field.
A
third
commenter
noted
that
subcategorization
and
source
category
deletions
under
CAA
section
112(
c)
have
been
implemented
several
times
since
the
MACT
program
began.

Some
commenters
pointed
out
that
they
have
not
been
able
to
comment
on
the
technical
merit
of
the
risk
analysis
employed
by
the
EPA.
They
argued
that,
until
the
residual
risk
analysis
procedures
have
been
implemented
via
the
CAA
section
112(
f)
process,
risk
analysis
should
not
be
used
in
making
MACT
determinations
pursuant
to
CAA
section
112(
d)(
4).
Also,
risk
analysis
could
never
be
used
to
establish
a
MACT
floor.

One
commenter
pointed
out
that,
in
separate
rulemakings
and
lawsuits,
EPA
adopted
legal
positions
and
policies
that
221
they
claimed
refute
and
contradict
the
very
risk­
based
and
cost­
based
approaches
contained
in
the
proposal.
In
these
other
arenas,
EPA
properly
rejected
risk
assessment
to
alter
the
establishment
of
MACT
standards.
The
EPA
also
properly
rejected
cost
in
determining
MACT
floors
and
in
denying
a
basis
for
avoiding
the
MACT
floor.
(
See
Brief
for
Respondent
Environmental
Protection
Agency,
Sierra
Club
v.

EPA;
Brief
for
Respondent
Environmental
Protection
Agency,

Cement
Kiln
Recycling
Coalition
v.
EPA,
No.
99­
1457
and
consolidated
cases,
(
D.
C.
Cir.)
(
Jan.
18,
2001);
Brief
for
Respondent
Environmental
Protection
Agency,
National
Lime
Ass'n
v.
EPA,
233
F.
3D
625
(
D.
C.
Cir.
2000)
(
July
14,

2000).)

Response:
We
feel
that
the
assertions
by
one
commenter
about
the
negative
environmental
disbenefits
of
the
PCWP
rule
as
proposed
are
overstated.
We
disagree
that
the
PCWP
industry
as
a
whole
poses
a
small­
to­
insignificant
risk
to
human
health
and
the
environment.
However,
we
acknowledge
that
there
are
some
PCWP
facilities
that
pose
little
risk
to
human
health
and
the
environment.
Consequently,
we
have
included
an
option
in
today's
final
PCWP
rule
that
would
allow
individual
facilities
to
be
found
eligible
for
membership
in
a
delisted
low­
risk
subcategory
if
they
demonstrate
that
they
do
not
pose
a
significant
risk
to
human
health
or
the
environment.
The
low­
risk
subcategory
222
delisting
in
today's
final
PCWP
rule
is
based
on
our
authority
under
CAA
sections
112(
c)(
1)
and
(
9).
The
statute
requires
that
categories
or
subcategories
meet
specific
risk
criteria
in
order
to
be
delisted.
To
determine
whether
source
categories
and
subcategories,
and
their
constituent
sources,
meet
these
criteria,
risk
analyses
may
be
used.
We
disagree
with
the
commenter
that
we
must
wait
for
implementation
of
CAA
section
112(
f)
before
utilizing
risk
analysis
in
this
manner.
Section
112(
d)(
1)
of
the
CAA
gives
us
the
authority
to
distinguish
among
classes,
types,
and
sizes
of
sources
within
a
category,
and
CAA
section
112(
c)(
1)
does
not
restrict
our
authority
to
base
categories
and
subcategories
on
other
appropriate
criteria.
As
discussed
in
more
detail
elsewhere
in
this
notice,
we
feel
these
provisions
of
the
CAA
allow
us
to
define
a
subcategory
of
sources
in
terms
of
risk.
Thus,
the
low­
risk
subcategory
of
PCWP
facilities
is
defined
in
terms
of
risk,
not
cost.

We
are
not
subcategorizing
or
determining
MACT
floors
based
on
cost.
Furthermore,
because
most
facilities
will
make
their
low­
risk
demonstrations
following
promulgation
of
today's
final
PCWP
rule,
the
MACT
level
of
emissions
reduction
required
by
today's
final
rule
is
not
affected
by
facilities
becoming
part
of
the
low­
risk
subcategory.

We
are
not
pursuing
the
risk­
based
exemptions
based
on
CAA
section
112(
d)(
4).
We
do
not
feel
that
a
risk­
based
223
approach
based
on
section
112(
d)(
4)
is
appropriate
for
the
PCWP
industry
because
PCWP
facilities
emit
HAP
for
which
no
health
thresholds
have
been
established
and
because
the
legislative
history
of
the
1990
Amendments
to
the
CAA
indicates
that
Congress
considered
and
rejected
allowing
us
to
grant
such
source­
specific
exemptions
from
the
MACT
floor.
We
also
are
not
relying
on
de
minimis
authority.

Legal
issues
associated
with
the
risk­
based
provisions
are
addressed
elsewhere
in
this
preamble.

In
today's
final
PCWP
rule,
we
are
identifying
the
criteria
we
will
use
to
identify
low­
risk
PCWP
facilities
and
requesting
that
any
candidate
facilities,
in
addition
to
the
facilities
already
identified
as
low
risk
in
today's
action,
submit
information
to
us
based
on
those
criteria
so
that
we
can
evaluate
whether
they
might
be
low­
risk.

Today's
final
PCWP
rule
also
establishes
a
low­
risk
PCWP
subcategory
based
on
the
criteria
(
and
including
several
identified
facilities)
and
delists
the
subcategory
based
on
our
finding
that
no
source
that
would
be
eligible
to
be
included
in
the
subcategory
based
on
our
adopted
criteria
emits
HAP
at
levels
that
exceed
the
thresholds
specified
in
section
112(
c)(
9)(
B)
of
the
CAA.
To
be
found
eligible
to
be
included
in
the
delisted
source
category,
facilities
will
have
to
demonstrate
to
us
that
they
meet
the
criteria
established
by
today's
final
PCWP
rule
and
assume
federally
224
enforceable
limitations
that
ensure
their
HAP
emissions
do
not
subsequently
increase
to
exceed
levels
reflected
in
their
eligibility
demonstrations.

The
criteria
defining
the
low­
risk
subcategory
of
PCWP
facilities
are
included
in
appendix
B
to
subpart
DDDD
of
40
CFR
part
63.
The
criteria
in
the
appendix
were
developed
for
and
apply
only
to
the
PCWP
industry
and
are
not
applicable
to
other
industries.
Today's
final
PCWP
rule
provides
two
ways
that
a
facility
may
demonstrate
that
it
is
part
of
the
low­
risk
subcategory
of
PCWP
facilities.
First,

look­
up
tables
allow
facilities
to
determine,
using
a
limited
number
of
site­
specific
input
parameters,
whether
emissions
from
their
sources
might
cause
a
hazard
index
(
HI)

limit
for
noncarcinogens
or
a
cancer
benchmark
of
one
in
a
million
to
be
exceeded.
Second,
a
site­
specific
modeling
approach
can
be
used
by
those
facilities
that
cannot
demonstrate
that
they
are
part
of
the
low­
risk
subcategory
using
the
look­
up
tables.

The
low­
risk
subcategory
delisting
that
is
included
in
today's
final
PCWP
rule
is
intended
to
avoid
imposing
unnecessary
controls
on
facilities
that
pose
little
risk
to
human
health
or
the
environment.
Facilities
will
have
to
select
controls
or
other
methods
of
limiting
risk
and
then
demonstrate,
using
appendix
B
to
subpart
DDDD
of
40
CFR
part
63
and
other
analytical
tools,
such
as
the
"
Air
Toxics
Risk
225
Assessment
Reference
Library,"
if
appropriate
in
a
source's
case,
that
their
emissions
qualify
them
to
be
included
in
the
low­
risk
subcategory,
and,
therefore,
to
not
be
subject
to
the
MACT
compliance
options
included
in
today's
final
PCWP
rule.

Comment:
Several
commenters
objected
to
EPA
using
the
preambles
of
individual
rule
proposals
as
the
forum
for
introducing
significant
changes
in
the
way
that
MACT
standards
are
established.
One
commenter
stated
that,
for
many
years,
it
has
coordinated
with
EPA
on
development
of
MACT
standards
for
the
national
air
toxics
program,
and
there
has
been
no
indication
of
any
kind
regarding
inclusion
of
risk­
based
exemptions
in
the
first
phase
of
the
MACT
program.
The
commenter
thought
it
was
unprecedented
and
alarming
that
EPA
was
proposing
such
a
radical
change
at
the
end
of
Phase
1
of
the
MACT
standard
process.
The
commenter
believed
that
allowing
risk­
based
exemptions
requires
changes
to
existing
law
and
that
such
a
debate
should
take
place
within
the
democratic
legislative
process
and
not
in
the
MACT
standard
process.
Another
commenter
stated
that
precedent­
setting
changes
of
the
magnitude
that
EPA
has
raised
should
be
discussed
openly
and
carefully
with
all
affected
parties
instead
of
being
buried
in
the
preambles
of
individual
standards.
A
third
commenter
expressed
concern
that
other
parties
may
miss
commenting
on
the
risk­
based
226
exemptions
because
they
are
contained
within
six
separate
proposals.
The
commenter
added
that
to
give
the
issue
full
consideration,
the
risk
provisions
should
not
be
adopted
within
any
of
the
final
rules
but
should
be
addressed
in
one
place,
such
as
in
revisions
to
the
General
Provisions
of
40
CFR
part
63,
subpart
A.

Response:
The
discussion
of
risk­
based
provisions
in
MACT
was
included
in
individual
proposals
for
several
reasons.
First,
we
recognize
that
such
provisions
might
only
be
appropriate
for
certain
source
categories,
and
our
decision­
making
process
required
source
category­
specific
input
from
stakeholders.
Second,
the
10­
year
MACT
standards,
which
are
now
being
completed,
are
the
last
group
of
MACT
standards
currently
planned
for
development,
and
for
any
risk
provisions
to
be
useful,
the
provisions
must
be
finalized
in
a
timely
manner.
Third,
the
risk­
based
provisions
are
not
available
for
any
other
standards
that
have
already
been
implemented,
and
any
decisions
regarding
risk
must,
therefore,
be
applied
on
a
source
category
specific
basis.
We
do
not
agree
that
changes
to
existing
law
are
necessary
because
of
the
discretion
provided
to
the
Administrator
under
CAA
section
112(
d)(
1)
to
distinguish
among
classes,
types,
and
sizes
of
sources
within
a
category
and
under
CAA
section
112(
c)(
1)
to
base
categories
and
subcategories
on
any
appropriate
criteria.
We
consider
low­
227
risk
facilities
to
be
an
appropriate
subcategory
of
sources
within
the
PCWP
source
category.

Comment:
Several
commenters
stated
that
the
risk­
based
exemption
proposal
removes
the
level
playing
field
that
would
result
from
the
proper
implementation
of
technologybased
MACT
standards.
According
to
the
commenters,

establishing
a
baseline
level
of
control
is
essential
to
prevent
industry
from
moving
to
areas
of
the
country
that
have
the
least
stringent
air
toxics
programs,
which
was
one
of
the
primary
goals
of
developing
a
uniform
national
air
toxics
program
under
section
112
of
the
1990
CAA
amendments.

The
commenters
argued
that
risk­
based
approaches
would
jeopardize
future
reductions
of
HAP
in
a
uniform
and
consistent
manner
across
the
nation.
One
commenter
stated
that
National
Air
Toxics
Assessment
(
NATA)
data
show
that
virtually
no
area
of
the
country
has
escaped
measurable
concentrations
of
toxic
air
pollution.
The
NATA
information
indicates
that
exposure
to
air
toxics
is
high
in
both
densely
populated
and
remote
rural
areas.

One
commenter
disagreed
with
the
assertion
that
the
level
playing
field
would
be
removed.
The
commenter
pointed
out
that
the
argument
that
EPA
should
impose
unnecessary
and
potentially
environmentally
damaging
controls
for
the
sole
purpose
of
equalizing
control
costs
across
facilities
would
be
at
odds
with
the
stated
purpose
of
the
CAA.
According
to
228
the
commenter,
the
claim
that
the
risk­
based
approach
would
favor
facilities
located
away
from
population
centers
is
incorrect.
As
contemplated,
the
risk­
based
approaches
to
the
NESHAP
would
be
keyed
to
the
comparison
of
health
benchmarks
with
potential
maximum
exposure,
regardless
of
whether
actual
receptors
are
present
at
the
exposure
location.
According
to
the
commenter,
the
presence
or
absence
of
human
populations
would
have
no
effect
on
whether
facilities
would
qualify.

Response:
We
agree
that
one
of
the
primary
goals
of
developing
a
uniform
national
air
toxics
program
under
section
112
of
the
1990
CAA
amendments
was
to
establish
a
level
playing
field.
We
do
not
feel
that
defining
a
lowrisk
subcategory
in
today's
final
PCWP
rule
does
anything
to
remove
the
level
playing
field
for
PCWP
facilities.
Today's
final
PCWP
rule
and
its
criteria
for
demonstrating
eligibility
for
the
delisted
low­
risk
subcategory
apply
uniformly
to
all
PCWP
facilities
across
the
nation.
Today's
final
PCWP
rule
establishes
a
baseline
level
of
emission
reduction
or
a
baseline
level
of
risk
(
for
the
low­
risk
subcategory).
All
PCWP
facilities
are
subject
to
these
same
baseline
levels,
and
all
facilities
have
the
same
opportunity
to
demonstrate
that
they
are
part
of
the
delisted
low­
risk
subcategory.
The
criteria
for
the
lowrisk
subcategory
are
not
dependent
on
local
air
toxics
229
programs.
Therefore,
concerns
regarding
facilities
moving
to
areas
of
the
country
with
less­
stringent
air
toxics
programs
should
be
alleviated.

Although
NATA
may
show
measurable
concentrations
of
toxic
air
pollution
across
the
country,
these
data
do
not
suggest
that
PCWP
facilities
that
do
not
contribute
to
the
high
exposures
and
risk
should
be
included
in
MACT
regulations,
notwithstanding
our
authority
under
CAA
section
112(
c)(
9).
A
discussion
is
provided
elsewhere
in
this
section
regarding
how
background
concentrations
are
accounted
for
by
facilities
demonstrating
eligibility
for
the
delisted
low­
risk
subcategory.

Comment:
One
commenter
stated
that
the
dockets
for
the
MACT
proposals
that
contain
the
risk
approaches
make
it
clear
that
the
White
House
Office
of
Management
and
Budget
(
OMB)
and
industry
were
the
driving
forces
behind
the
appearance
of
these
unlawful
approaches
in
EPA's
proposals.

The
commenter
cited
internal
e­
mails
between
the
White
House
OMB
and
EPA
that
it
asserts
reveal
OMB
officials
exerting
pressure
on
EPA
to
take
ownership
of
the
deregulatory
approaches
developed
by
industry.
The
commenter
noted
that
comparison
of
the
proposal
language
for
both
the
Brick
and
Structural
Clay
Products
(
BSCP)
rule
and
PCWP
rule
makes
it
clear
that
EPA
capitulated
to
OMB
pressure
to
remove
references
to
the
risk­
based
exemptions
in
the
PCWP
proposal
230
preamble
as
being
industry's
suggested
approaches,
according
to
the
commenter.
The
commenter
cited
preamble
edits
from
OMB
that
the
commenter
believes
reveals
an
OMB
agenda
to
dictate
EPA
adoption
of
industry's
risk­
based
approaches,

and
to
signal
these
plans
in
the
rulemaking
proposals,
even
before
public
comment
has
been
taken.
The
commenter
also
noted
that
OMB
urged
support
of
a
dangerous
and
technically
unfounded
HI
of
10.0.
The
commenter
condemned
the
industry­
driven
agenda
that
it
claimed
is
being
promoted
by
the
White
House
OMB.

A
second
commenter
stated
that
the
accusations
that
EPA
succumbed
to
industry
lobbying
and
internal
pressures
are
entirely
unfounded.
The
commenter
stated
that
risk­
based
approaches
are
warranted
because
EPA's
NESHAP
program
has
now
turned
to
the
low­
risk
source
categories
that
Congress
instructed
EPA
to
address
last.
The
commenter
pointed
out
that
80
source
categories
have
already
been
addressed
with
MACT
standards.
According
to
the
commenter,
the
remaining
source
categories
are
lower
priority
and
include
a
large
number
of
facilities
that
pose
negligible
risk
to
public
health
and
environment.
The
commenter
stated
that
EPA
purposefully
saved
those
categories
for
last
in
accordance
with
Congress'
explicit,
risk­
based
priority­
setting
mandate
expressed
in
CAA
section
112(
e)(
2).
The
commenter
concluded
that
EPA
has
now
reached
the
point
where
regulation
by
MACT
231
would
result
in
more
environmental
harm
than
good.

Response:
The
first
commenter
is
correct
in
stating
that
industry
representatives
and
OMB
support
the
inclusion
of
risk­
based
approaches
in
today's
final
PCWP
rule
as
a
method
of
reducing
costs.
We
are
required
by
Executive
Order
12866
to
submit
to
OMB
for
review
all
proposed
and
final
rulemaking
packages
that
would
have
an
annual
effect
on
the
economy
of
$
100
million
or
more.
The
comments
we
received
from
OMB
reflect
their
position
that
low­
facilities
do
not
warrant
regulation.
However,
the
commenter
is
incorrect
in
implying
that
we
have
not
exercised
our
independent
judgment
in
addressing
these
issues.
Our
rationale
for
adopting
the
risk­
based
approach
in
this
PCWP
rulemaking
is
that
which
is
included
in
our
rulemaking
record,
and
is
not
based
on
an
inappropriate
abdication
of
our
dutiessuch
an
approach
is
fully
authorized
under
the
CAA.

Effects
on
MACT
program
Comment:
Several
commenters
expressed
concern
about
the
impact
of
a
risk­
based
approach
on
the
MACT
program.
Some
commenters
stated
that
the
proposal
to
include
risk­
based
exemptions
is
contrary
to
the
1990
CAA
Amendments,
which
calls
for
MACT
standards
based
on
technology
rather
than
risk
as
a
first
step.
The
commenters
pointed
out
that
Congress
incorporated
the
residual
risk
program
under
CAA
232
section
112(
f)
to
follow
the
MACT
standards,
not
to
replace
them.
One
commenter
added
that
risk­
based
approaches
would
be
used
separately
to
augment
and
improve
technology­
based
standards
that
do
not
adequately
provide
protection
to
the
public.

Another
commenter
believed
that
CAA
section
112(
d)(
4)

and
the
regulatory
precedent
established
in
over
80
MACT
standards
reject
the
inclusion
of
risk
in
the
first
phase
of
the
MACT
standards
process.
The
commenter
argued
that
the
use
of
risk
assessment
at
this
stage
of
the
MACT
program
is,

in
fact,
directly
opposed
to
title
III
of
the
CAA.

Response:
We
disagree
that
inclusion
of
a
low­
risk
subcategory
in
today's
final
PCWP
rule
is
contrary
to
the
1990
CAA
Amendments.
The
PCWP
MACT
rule
is
a
technologybased
standard
developed
using
the
procedures
dictated
by
section
112
of
the
CAA.
The
only
difference
between
today's
final
PCWP
rule
and
other
MACT
rules
is
that
we
used
our
discretion
under
CAA
sections
112(
c)(
1)
and
(
9)
to
subcategorize
and
delist
low­
risk
facilities,
in
addition
to
fulfilling
our
duties
under
CAA
section
112(
d)
to
set
MACT.

The
CAA
requires
that
categories
or
subcategories
meet
specific
risk
criteria,
and
to
determine
this,
risk
analyses
may
be
used.
We
disagree
with
the
commenter
that
we
must
wait
for
implementation
of
CAA
section
112(
f)
before
utilizing
risk
analysis
in
this
manner.
We
feel
that
233
today's
final
PCWP
rule
is
particularly
well­
suited
for
a
risk­
based
option
because
of
the
specific
pollutants
that
are
emitted
by
PCWP
sources.
For
many
facilities,
the
pollutants
are
emitted
in
amounts
that
pose
little
risk
to
the
surrounding
population.
However,
the
cost
of
controlling
these
pollutants
is
high,
and
may
not
be
justified
by
environmental
benefits
for
these
low­
risk
facilities.
Only
those
PCWP
facilities
that
demonstrate
that
they
are
low
risk
are
eligible
for
inclusion
in
the
delisted
low­
risk
subcategory.
The
criteria
included
in
today's
final
PCWP
rule
defining
the
delisted
low­
risk
subcategory
are
based
on
sufficient
information
to
develop
health­
protective
estimates
of
risk
and
will
provide
ample
protection
of
human
health
and
the
environment.

Inclusion
of
a
low­
risk
subcategory
in
today's
final
PCWP
rule
does
not
alter
the
MACT
program
or
affect
the
schedule
for
promulgation
of
the
remaining
MACT
standards.

We
recognize
that
such
provisions
are
only
appropriate
for
certain
source
categories,
and
our
decision­
making
process
required
source
category­
specific
input
from
stakeholders.

The
10­
year
MACT
standards,
which
are
now
being
completed,

are
the
last
group
of
MACT
standards
currently
planned
for
development,
and
for
any
risk
provisions
to
be
useful,
the
provisions
must
be
finalized
in
a
timely
manner.

Comment:
Several
commenters
stated
that
the
inclusion
234
of
a
risk­
based
approach
would
delay
the
MACT
program
and/
or
promulgation
of
the
PCWP
MACT
standard.
Commenters
stated
that
the
proposal
to
allow
risk­
based
exemptions
would
divert
back
to
the
time­
consuming
NESHAP
development
process
that
existed
prior
to
the
1990
CAA
Amendments.
Under
this
process,
which
began
with
a
risk
assessment
step,
only
eight
NESHAP
were
promulgated
during
a
20­
year
period.
If
the
proposed
approaches
are
inserted
into
upcoming
standards,

the
commenters
feared
the
MACT
program
(
which
is
already
far
behind
schedule)
would
be
further
delayed.

One
commenter
stated
that
they
were
strongly
opposed
to
returning
to
the
morass
of
risk­
based
analysis
in
an
attempt
to
preempt
the
application
of
technology­
based
MACT
standards
and
exempt
facilities.
The
commenter
stated
that
designing
a
risk­
based
analysis
procedure
would
also
take
significant
resources,
as
evidenced
by
the
fact
that
it
took
five
plus
pages
in
the
Federal
Register
to
discuss
just
the
basic
issues
to
be
considered
in
the
analysis.
The
commenter
indicated
that
the
demand
on
government
resources
could
cause
a
delay
in
the
application
of
MACT
nationwide.

The
commenter
stated
that
EPA
should
also
consider
the
issue
of
fairness
since
the
rest
of
the
industrial
sector
whose
NESHAP
have
already
been
promulgated
did
not
have
a
riskbased
option.

Another
commenter
stated
that
it
is
evident
that
the
235
proposed
risk­
based
exemptions
would
require
extensive
debate
and
review
in
order
to
launch,
which
would
further
delay
promulgation
of
the
remaining
MACT
standards.
The
commenter
stated
that
delays
could
be
exacerbated
by
litigation
following
legal
challenges
to
the
rules,
and
such
delays
would
trigger
the
CAA
section
112(
j)
MACT
hammer
provision,
which
would
unnecessarily
burden
the
State
and
local
agencies
and
the
industries.
The
commenter
concluded
that,
obviously,
further
delay
is
unacceptable.
Another
commenter
agreed,
stating
that
it
is
imperative
that
EPA
meet
the
new
deadlines
for
promulgating
the
final
MACT
standards.

Two
commenters
stated
that
EPA's
proposal
to
improperly
incorporate
risk
assessment
into
the
technology­
based
standard
process
would
cripple
a
MACT
program
already
in
disarray.
The
commenters
argued
that
the
risk­
based
approach
could
exacerbate
the
delay
in
HAP
emissions
reductions
required
by
CAA
section
112.
One
commenter
noted
that
EPA's
Office
of
Inspector
General
recently
found
that
EPA
is
nearly
2
years
behind
in
fulfilling
its
statutory
responsibilities
for
implementing
Phase
1
MACT
standards.

According
to
the
commenter,
this
delay
potentially
harms
the
public
and
environment.
The
inclusion
of
risk­
based
exemptions
in
10­
year
MACT
standards
would
only
further
delay
this
process.
The
other
commenter
noted
that
EPA
236
lacks
adequate
emissions
and
exposure
data,
source
characterization
data,
and
health
and
ecological
effects
information
to
conduct
this
process
anyway.
This
commenter
believed
that
the
air
toxics
program
is
flawed
and
failing
to
protect
public
health
and
the
environment
and
argued
that
it
was
irresponsible
for
EPA
to
pursue
a
deregulatory
agenda
that
would
further
weaken
the
effectiveness
of
the
air
toxics
program.
The
commenter
noted
that
EPA
acknowledged
the
complexity
and
delays
associated
with
the
proposed
riskbased
approaches
in
deciding
not
to
adopt
the
approaches
in
the
final
BSCP
rule.

Response:
We
disagree
that
identification
and
delisting
of
a
low­
risk
subcategory
in
today's
final
PCWP
rule
will
alter
the
MACT
program
or
affect
the
schedule
for
promulgation
of
the
remaining
MACT
standards,
especially
the
PCWP
MACT
rule.
In
fact,
it
has
not
caused
such
a
delay
for
the
final
rule.
We
do
not
anticipate
any
further
delays
in
completing
the
remaining
MACT
standards.
The
delisting
of
a
low­
risk
subcategory
in
today's
final
PCWP
rule
affects
only
the
PCWP
rule,
and
not
any
other
MACT
standards.

We
feel
that
the
final
PCWP
rule
is
particularly
wellsuited
for
a
risk­
based
option
because
of
the
specific
pollutants
that
are
emitted.
For
many
facilities,
the
pollutants
are
emitted
in
amounts
that
pose
little
risk
to
the
surrounding
population.
However,
the
cost
of
237
controlling
these
pollutants
is
high
and
may
not
be
justified
by
environmental
benefits
for
these
low­
risk
facilities.
Only
those
PCWP
facilities
that
demonstrate
that
they
are
low
risk
are
eligible
for
inclusion
in
the
delisted
low­
risk
subcategory.
The
criteria
defining
the
delisted
low­
risk
subcategory
are
based
on
sufficient
information
to
develop
health­
protective
estimates
of
risk
and
will
provide
ample
protection
of
human
health
and
the
environment.

Delisting
of
a
low­
risk
subcategory
of
PCWP
facilities
does
not
mean
that
we
will
provide
risk­
based
options
for
other
industries.
Furthermore,
we
have
no
intentions
of
reopening
previously
promulgated
NESHAP
in
light
of
decisions
made
specific
to
the
PCWP
source
category.
The
final
PCWP
NESHAP
is
being
promulgated
by
the
February
2004
court­
ordered
deadline.
Any
delays
in
implementation
of
the
final
PCWP
NESHAP
caused
by
legal
challenges,
which
could
and
often
do
occur
for
any
MACT
standard
we
promulgate
without
a
risk­
based
approach,
are
beyond
our
control.

2.
Legal
authority
Section
112(
d)(
4)
of
the
CAA
Comment:
We
received
multiple
comments
stating
that
CAA
section
112(
d)(
4)
provides
EPA
with
authority
to
exclude
sources
that
emit
threshold
pollutants
from
regulation.
The
commenters
cited
the
language
in
section
112(
d)(
4)
and
CAA
238
legislative
history.
The
commenters
pointed
out
that
EPA
exercised
its
section
112(
d)(
4)
authority
previously
in
choosing
not
to
impose
control
requirements
on
hydrogen
chloride
(
HCl)
emissions
from
chemical
recovery
furnaces
at
pulp
mills
(
40
CFR
part
63,
subpart
MM,
see
63
FR
18754,

18765
(
April
15,
1998)).

We
also
received
multiple
comments
disagreeing
that
CAA
section
112(
d)(
4)
can
be
interpreted
to
allow
exemptions
for
individual
sources.
The
commenters
argued
that
section
112(
d)(
4)
applies
only
to
categories
or
subcategories
of
sources
and
not
to
individual
sources.
These
commenters
also
cited
the
language
of
section
112(
d)(
4)
and
CAA
legislative
history.
The
commenters
interpreted
section
112(
d)(
4)
to
state
that
health­
based
thresholds
can
be
considered
when
establishing
the
degree
of
the
MACT
floor
requirements,
but
they
should
not
be
used
in
lieu
of
the
requirements
established
pursuant
to
section
112(
d)(
3).
One
commenter
also
argued
that
the
third
scenario
suggested
by
EPA
 
application
of
section
112(
d)(
4)
exemption
to
emission
points
within
a
facility
 
is
unlawful
because
there
is
no
statutory
provision
within
the
CAA
to
authorize
emission
point­
by­
point
exemption.

Several
commenters
supported
the
use
of
a
CAA
section
112(
d)(
4)
applicability
cutoffs
for
both
threshold
and
non­
threshold
pollutants
and
believe
that
a
health
threshold
239
of
one
in
a
million
cancer
risk
is
appropriate
for
non­
threshold
pollutants.
The
commenters
interpreted
the
language
in
section
112(
d)(
4)
to
mean
EPA
may
issue
standards
for
any
pollutant
for
which
a
threshold
may
be
established.
The
commenters
believe
that
EPA
could
use
its
section
112(
d)(
4)
authority
to
establish
a
threshold
risk
of
one
in
a
million
for
non­
threshold
carcinogens.
The
commenters
also
believe
that
section
112(
d)(
4)
may
be
properly
applied
to
carcinogenic
HAP
that
EPA
determines
have
a
threshold
of
safe
exposure.
The
commenters
claimed
that
the
current
health
science
for
formaldehyde
and
acetaldehyde
shows
that
these
two
HAP
are
threshold
carcinogens
that
are
emitted
from
wood
products
facilities
at
levels
that
will
not
pose
a
significant
risk
to
human
health.

Multiple
other
commenters
stated
that
CAA
section
112(
d)(
4)
does
not
apply
for
source
categories
that
emit
carcinogens.
The
commenters
argued
that
EPA
may
only
use
the
section
112(
d)(
4)
authority
for
pollutants
with
a
well­
established
health
threshold.
The
commenters
stated
that
section
112(
d)(
4)
only
allows
EPA
to
substitute
a
health
threshold
for
a
MACT
standard
when
the
threshold
has
been
established.
The
commenters
contended
that
Congress
did
not
intend
for
EPA
to
spend
time
determining
if
a
threshold
exists
and
that
it
was
Congress'
intent
that
EPA
240
have
a
high
degree
of
scientific
certainty
before
using
its
section
112(
d)(
4)
authority.
The
commenters
cited
legislative
history.
(
See
S.
Rep.
101­
228
at
171.)
The
commenters
also
stated
that
Congress
specified
that
EPA
must
have
direct
evidence
of
no
effects,
i.
e.,
use
of
a
no
observable
effects
level
(
NOEL),
before
invoking
section
112(
d)(
4);
thus,
EPA
must
be
sure
that
there
are
no
effects
from
exposure
at
the
level
chosen
for
the
emission
standard.

The
commenters
further
argued
that
all
carcinogens
must
be
treated
as
non­
threshold
pollutants
and
noted
that
the
history
of
the
1990
CAA
Amendments
shows
that
Congress
legislated
with
an
understanding
that
carcinogens
do
not
have
a
safe
threshold.

Response:
We
acknowledge
the
commenters'
arguments
regarding
our
discussion
in
the
PCWP
proposal
preamble
regarding
potential
applicability
cutoffs
for
threshold
pollutants
under
the
authority
of
section
112(
d)(
4)
of
the
CAA.
We
feel
that
section
112(
d)(
4)
does
not
give
us
the
authority
to
exempt
facilities
or
emission
points
from
MACT
limitations
on
non­
threshold
pollutant
emissions.
All
PCWP
facilities
emit
carcinogens
(
e.
g.,
formaldehyde),
which
are
currently
considered
non­
threshold
pollutants.
Therefore,

we
are
not
using
section
112(
d)(
4)
authority
to
create
riskbased
options
for
PCWP.
We
do
not
expect
to
further
explore
the
use
of
section
112(
d)(
4)
of
the
CAA
to
exempt
PCWP
241
facilities
from
the
MACT
floor
on
a
case­
by­
case
basis
or
to
set
alternative
standards,
because
PCWP
facilities
emit
HAP
for
which
no
health
thresholds
have
been
established
and
because
the
legislative
history
to
the
1990
Amendments
to
the
CAA
indicates
that
Congress
considered
and
rejected
allowing
us
to
grant
such
source­
specific
exemptions
from
the
MACT
floor.
(
See,
e.
g.,
1
Legis.
Hist.
at
866,
877;
2
Legis.
Hist.
at
2141­
42,
3939.)
As
discussed
below,
we
are
establishing
and
delisting
a
subcategory
of
low­
risk
PCWP
facilities
using
our
authority
under
CAA
sections
112(
c)(
1)

and
(
9).

We
are
establishing
criteria
in
today's
final
PCWP
rule
that
define
a
low­
risk
subcategory
of
PCWP
facilities,
which
requires
demonstration
that
a
facility
warrants
being
included
in
this
subcategory.
The
criteria
are
not
included
in
the
rule
as
emission
standards
or
emission
limits
but
are
included
in
an
appendix
to
the
rule
that
specifies
how
facilities
must
make
their
low­
risk
demonstrations
and
the
steps
that
facilities
must
take
to
ensure
that
they
remain
in
the
low­
risk
subcategory.
We
are
not
setting
a
riskbased
emission
limit,
but,
rather,
we
are
using
our
CAA
section
112(
c)(
9)
authority
to
delist
facilities
that
demonstrate
they
meet
the
risk
and
hazard
criteria
for
being
included
in
this
low­
risk
subcategory.

De
minimis
242
Comment:
Some
commenters
attempted
to
identify
a
source
of
authority
for
risk­
based
approaches
that
was
not
discussed
in
the
preamble
to
the
proposed
rule.
The
commenters
stated
that
a
risk­
based
compliance
option
for
both
threshold
and
non­
threshold
HAP
is
well
within
EPA's
authority
under
the
CAA
and
the
de
minimis
doctrine
articulated
by
appellate
courts.
The
commenters
cited
appellate
case
law
which
they
believe
makes
it
clear
thatholds
EPA
may
lawfully
exempt
de
minimis
sources
of
risk
from
MACT­
level
controls
because
the
legislative
mandate
of
CAA
section
112
is
not
extraordinarily
rigid
and
the
exemption
is
consistent
with
the
CAA's
health­
protective
purpose.
The
commenters
also
argued
that
CAA
sections
112(
c)(
9)
and
112(
f)(
2)
indicate
that
Congress
considered
a
cancer
risk
below
one
in
a
million
to
be
de
minimis
and,

therefore,
insufficient
to
justify
regulation
under
section
112.
The
commenters
stated
that
(
and
cited
examples
where)

EPA's
exercise
of
de
minimis
authority
has
withstood
judicial
challenge,
and
that
application
of
de
minimis
authority
(
as
well
as
its
treatment
by
reviewing
courts)
is
based
on
the
degree
of
risk
at
issue,
not
on
the
mass
of
emissions
to
be
regulated.
The
commenters
stated
that
the
D.
C.
Circuit
has
invalidated
EPA's
de
minimis
authority
only
where
it
was
applied
under
statutory
designs
that
are
extraordinarily
rigid.
The
commenters
stated
that
CAA
243
section
112
provides
clear
indication
of
Congressional
intent
as
to
the
degree
of
risk
that
properly
is
to
be
considered
de
minimis.
A
cancer
risk
of
one
in
a
million
triggers
further
review
under
the
residual
risk
provision
of
CAA
section
112(
f),
and
a
one
in
a
million
cancer
risk
is
the
threshold
below
which
EPA
is
authorized
under
CAA
section
112(
c)(
9)(
B)
to
remove
source
categories
from
MACT
regulation.
One
commenter
attached
a
paper
they
developed
entitled
"
Legal
and
Policy
Basis
for
EPA's
Exercise
of
Its
De
minimis
Authority
Under
Section
112
of
the
Clean
Air
Act
in
the
Context
of
the
Wood
Products
MACT."

Other
commenters
argued
that
de
minimis
authority
does
not
exist
to
create
MACT
exemptions
on
a
facility­
by­
facility
or
category­
wide
basis.
In
addition,

tThe
commenters
stated
that
EPA
lacks
de
minimis
authority
to
delist
subcategories
based
on
risk.
The
commenters
cited
case
law
and
stated
that
EPA
may
not
rely
on
its
narrow
de
minimis
exemption
authority
to
escape
the
highly
prescriptive
provisions
in
section
112.
The
commenters
further
noted
that
EPA
has
not
revealed
any
administrative
record
justifying
a
de
minimis
exemption,
to
demonstrate
in
any
way
that
compliance
with
MACT
would
yield
a
gain
of
trivial
or
no
value.

Response:
We
disagree
with
the
commenters
who
claimed
that
the
low­
risk
approaches,
especially
the
concentration­
244
based
exemption,
can
be
justified
by
de
minimis
principles.

Our
de
minimis
authority
exists
to
help
avoid
excessive
regulation
of
tiny
amounts
of
pollutants,
where
regulation
would
yield
a
result
contrary
to
a
primary
legislative
goal.

It
is
unavailable
where
the
regulatory
function
does
provide
benefits,
in
the
sense
of
furthering
the
regulatory
objectives,
but
the
agency
concludes
that
the
acknowledged
benefits
are
exceeded
by
the
costs.
EDF
v.
EPA,
82
F.
3d
451,
466
(
D.
C.
Cir.
1996);
Public
Citizen
v.
Young,
831
F.
2d
1108,
1112­
13
(
D.
C.
Cir.
1987);
Alabama
Power
v.
EPA,
636
F.
2d
323,
360­
61
&
n.
89
(
D.
C.
Cir.
1979).
Accordingly,
a
de
minimis
exemption
to
CAA
section
112(
d)(
3)
is
unavailable
in
today's
final
PCWP
rule
because
it
would
frustrate
a
primary
legislative
goal
by
preventing
application
of
the
MACT
floor
to
tons
of
PCWP
facilities'
HAP
emissions.

The
U.
S.
Court
of
Appeals
for
the
District
of
Columbia
Circuit
has
already
addressed
the
de
minimis
concept
in
the
MACT
context,
in
National
Lime
Ass'n
v.
EPA,
233
F.
3d
625,

640
(
D.
C.
Cir.
2000)
(
National
Lime),
in
which
the
court
rejected
the
industry
petitioner's
claim
that,
in
light
of
both
the
high
costs
and
low
quantities
of
HAP
at
issue
in
that
case,
we
should
read
a
de
minimis
exception
into
the
requirement
that
it
regulate
all
HAP
emitted
by
major
sources.
In
that
case,
the
Court
found
that
"
EPA
reasonably
rejected
this
argument
on
the
ground
that
the
statute
`
does