CALPUFF
ANALYSIS
IN
SUPPORT
OF
THE
JUNE
2005
CHANGES
TO
THE
REGIONAL
HAZE
RULE
June
15,
2005
1
The
following
is
in
support
of
the
June
2005
revisions
to
the
Regional
Haze
Rule
(
RHR)
and
the
Guidelines
for
Best
Available
Retrofit
Technology
(
BART)
Determinations
under
the
regional
haze
rule.
The
report
documents
a
portion
of
the
work
involving
the
exercise
of
the
CALPUFF
dispersion
model
for
assessing
visibility
impairment
associated
with
proto­
typical
BART
eligible
coal­
fired
EGUs
and
industrial
boilers.
The
procedures
used
to
set
up
these
analyses,
the
numerous
intermediate
steps,
and
the
modeling
results
were
shared
and
discussed
with
EPA
staff
involved
in
revising
the
regional
haze
rule
over
a
period
of
eighteen
months
or
more.

Background
To
reduce
haze,
and
to
meet
the
requirements
of
the
Clean
Air
Act,
EPA
in
April
1999
issued
a
regional
haze
rule
aimed
at
protecting
visibility
in
156
federal
areas.
The
rule
seeks
to
reduce
the
visibility
impairment
caused
by
many
sources
over
a
wide
area.
EPA's
previous
visibility
regulation,
issued
in
1980,
addressed
only
local
visibility
impairment
from
local
sources.
Soon
after
the
regional
haze
rule
was
finalized,
several
parties
filed
petitions
challenging
the
rule
with
the
U.
S.
Court
of
Appeals
for
the
D.
C.
Circuit.
Because
regional
haze
is
a
problem
caused
by
multiple
sources
over
a
wide
area,
EPA's
rule
required
that
states
(
in
determining
BART
requirements)
assess
visibility
impairment
on
a
cumulative
basis
using
a
regional
air
quality
model;

i.
e.,
as
opposed
to
assessing
visibility
impairment
on
a
source­
by­
source
basis.
In
May
2002,
the
court
ruled
that
EPA's
approach
to
BART
was
not
acceptable;
specifically,
the
court
maintained
that
the
approach
infringed
on
States'
discretion
by
not
providing
an
option
for
States
to
make
BART
determinations
on
an
individual,
source­
by­
source
basis.
Consequently,
the
court
vacated
portions
of
the
regional
haze
rule
related
to
BART
and
remanded
to
EPA
for
appropriate
actions.

Use
of
CALPUFF
for
Regional
Haze
One
of
the
first
challenges
encountered
in
responding
to
the
court's
remand
involved
the
applicability
of
the
CALPUFF
dispersion
model;
currently,
CALPUFF
is
the
only
dispersion
model
with
capability
for
estimating
secondarily
formed
particulates
(
a
critical
ingredient
in
the
2
regional
haze
problem).
The
challenge
we
encountered
is
that
CALPUFF,
has
not
yet
been
fully
tested
for
secondary
formation
and
thus
is
not
fully
approved
for
regulatory
applications
such
as
PSD
and
NAAQS
attainment
demonstrations
(
i.
e.,
it
is
approved
for
primary
particulates,
but
not
for
secondarily­
formed
particulates).
Our
justification
for
using
CALPUFF
for
BART
is
that,

unlike
PSD
and
NAAQS,
the
BART
modeling
results
do
not,
by
themselves,
determine
the
regulatory
consequences.
We
believe
that
CALPUFF
is
based
on
sufficiently
sound
technical
grounds
to
support
assessments
of
relative
impacts
among
BART­
eligible
sources
for
the
purposes
of
guiding
more
refined
analyses
and
to
help
inform
regulatory
decisions
that
are
based
on
a
cumulative
weight
of
evidence,
such
as
the
statutorily­
defined
factors
for
consideration
in
assessing
BART
for
regional
haze.

The
BART
Process
The
BART
process
consists
of
the
following:

1.
Identify,
in
accordance
with
CAA
Section
169A(
b)(
2),
whether
a
source
is
"

BARTeligible
based
on
its
source
category,
when
it
was
put
in
service,
and
its
emissions
of
one
or
more
"
visibility­
impairing"
air
pollutants
including,
gaseous
precursors
to
visibilityimpairing
particulate
matter.

2.
Determine
whether
a
BART­
eligible
source
is
"
subject
to
BART"
(
for
any
visibilityimpairing
pollutant),
based
on
an
estimate
of
the
source's
impact
on
visibility.

3.
Determine
BART
for
the
source
by
evaluating
control
options
and
selecting
the
"
best"

alternative,
taking
into
consideration:

!
The
costs
of
compliance,

!
The
energy
and
non
air­
quality
environmental
impacts
of
compliance,
3
!
Any
existing
pollution
control
technology
in
use
at
the
source,

!
The
remaining
useful
life
of
the
source,
and
!
The
degree
of
improvement
in
visibility
that
may
reasonably
be
anticipated
to
result
from
the
use
of
BART.

Our
support
to
the
BART
process
is
focused
on
step
2,
determining
whether
a
BART­
eligible
source
is
subject
to
BART
based
on
an
estimate
of
its'
impact
on
visibility.
Our
approach
to
this
task
involved
:
(
1)
selection
of
sources
to
analyze,
(
2)
creation
of
modeling
domains
to
provide
separate
analyses
for
eastern
and
western
locations,
and
(
3)
use
of
a
range
of
emission
rates
to
bracket
analyses
of
most
interest/
use
to
decision
making
for
the
BART
rule.
In
the
process
of
selecting
sources
for
analyses
we
ended
up
constructing
proto­
typical
sources
to
represent
two
important
categories
in
of
the
universe
of
BART­
eligible
sources:
coal­
fired
boilers
used
to
power
electrical
generating
units
(
EGUs)
and
coal­
fired
industrial
boilers.
This
process
resulted
in
a
total
of
23
scenarios
for
analysis.
Source
characteristics
and
emission
rates
for
the
23
scenarios
are
given
in
Table
1.
The
source
characteristics
are
median
values
based
on
representative
samples
of
BART
eligible
units.
The
emission
rates
were
selected
to
address
various
questions
related
to
the
implementation
of
the
BART
requirement.
It
should
be
noted
that
although
the
emission
rates
are
given
in
units
of
tons
per
year,
there
is
no
presumption
that
the
values
are
actual
or
allowable.
4
Table
1
Emission
rates
and
source
parameters
used
in
CALPUFF
modeling
for
BART
Eligible
coal­
fired
boilers
Emission
rates
(
tpy)
Run
#
Source
ID
Hgt
Elev
Diam
Vel
Temp
SO2
NOx
PM25
Domain
(
m)
(
m)
(
m)
(
m/
s)
(
K)

1
EGU_
E#
1
100
200
8.0
27.0
400
10000
3500
50
Eastern
2
EGU_
W#
2
100
200
8.0
27.0
400
10000
6250
50
Western
3
EGU_
E#
3
100
200
8.0
27.0
400
5000
3500
50
Eastern
4
EGU_
W#
4
100
200
8.0
27.0
400
5000
6250
50
Western
5
EGU_
E#
5
100
200
8.0
27.0
400
1000
3500
50
Eastern
6
EGU_
W#
6
100
200
8.0
27.0
400
1000
6250
50
Western
7
EGU_
E#
7
100
200
8.0
27.0
400
1000
350
50
Eastern
8
EGU_
W#
8
100
200
8.0
27.0
400
1000
625
50
Western
9
EGU_
E#
9
100
200
8.0
27.0
400
30000
10000
50
Eastern
10
EGU_
E#
10
100
200
8.0
27.0
400
3000
10000
50
Eastern
11
EGU_
E#
11
100
200
8.0
27.0
400
3000
1000
50
Eastern
12
IB_
E#
12
55
200
2.6
11.4
414
7000
1400
20
Eastern
13
IB_
W#
13
55
200
2.6
11.4
414
7000
1400
20
Western
14
IB_
E#
14
55
200
2.6
11.4
414
900
1400
20
Eastern
15
IB_
W#
15
55
200
2.6
11.4
414
900
1400
20
Western
16
IB_
E#
16
55
200
2.6
11.4
414
900
300
20
Eastern
17
IB_
W#
17
55
200
2.6
11.4
414
900
300
20
Western
18
IB_
E#
18
55
200
2.6
11.4
414
0
1000
20
Eastern
19
IB_
E#
19
55
200
2.6
11.4
414
0
500
20
Eastern
20
IB_
W#
20
55
200
2.6
11.4
414
0
1000
20
Western
21
IB_
W#
21
55
200
2.6
11.4
414
0
500
20
Western
22
IB_
E#
22
55
200
3.1
11.4
478
7000
1400
20
Eastern
23
IB_
W#
23
55
200
3.1
11.4
478
7000
1400
20
Western
Key
to
Source
ID
EGU
Electrial
Generating
Unit
IB
Industrial
Boiler
_
E
indicates
the
Eastern
domain
_
W
indicates
the
Western
domain
#
nn
indicates
the
run
number
1
Revision
to
the
Guideline
on
Air
Quality
Models:
Adoption
of
a
Preferred
Long
Range
Transport
Model
and
Other
Revisions;
Final
Rule,
Federal
Register/
Vol.
68,
No.
72
/
April
15,
2003
5
CALPUFF
CALPUFF
is
an
advanced
meteorological
and
air
quality
modeling
system
recommended
by
the
U.
S.
EPA
as
the
preferred
tool
for
evaluating
impacts
associated
with
the
long
range
transport
of
primary
pollutants.
It
was
promulgated
for
regulatory
use
in
specific
circumstances
in
the
Guideline
on
Air
Quality
Models,
Appendix
W
to
40
CFR
Part
511.
CALPUFF
is
recommended
by
the
Inter
Agency
Workgroup
on
Air
Quality
Models
(
IWAQM)
for
use
in
evaluating
impacts
on
visibility
in
the
156
Federal
Class
I
areas.
The
modeling
system
consists
of
three
main
components:
CALMET
(
a
diagnostic
3­
dimensional
meteorological
model),
CALPUFF
(
an
air
quality
dispersion
model),
and
CALPOST
(
a
postprocessing
package).

With
few
exceptions
we
have
used
the
default
CALPUFF
settings
as
recommended
in
the
IWAQM
Phase
II
report.
Our
setups
(
selections
of
model
options
and
switch
settings)
for
the
three
CALPUFF
modules
(
CALMET,
CALPUFF,
and
CALPOST)
are
documented
in
the
example
command
file
input
images
provided
in
appendix
A.
Complete
documentation
on
our
use
of
CALPUFF
for
BART
is
included
on
a
DVD
which
is
being
provided
to
the
docket
for
the
June
2005
changes
to
the
regional
haze
rule.
In
the
following
we
highlight
portions
of
this
material.

As
mentioned
previously,
we
created
two
modeling
domains
(
east
and
west)
for
use
in
evaluating
the
potential
effects
of
our
proto­
typical
BART
eligible
sources
The
two
domains
are
identical
in
terms
of
the
overall
size
(
dimensions)
and
grid
spacing.
Each
domain
is
a
600
x
600
km
square
sectioned
into
75
x
75
horizontal
grid
cells
and
10
vertical
layers;
the
horizontal
grid
spacing
is
8
km.,
vertical
levels
are
located
at
20,50,75,
100,
250,
500,
750,
1000,
2000,
and
3000
m.

The
location
of
the
domain
determines
which
meteorological
stations
will
be
used
in
CALMET
to
build
the
three­
dimensional
wind
fields
used
in
CALPUFF.
The
Eastern
domain
is
centered
over
6
West
Virginia
and
uses
meteorological
data
for
5
upper­
air
stations
and
22
surface
stations
(
see
Table
A­
2).
The
Western
domain
is
centered
over
Denver
and
uses
meteorological
data
for
3
upper­
air
stations
and
12
surface
stations
(
see
Table
A­
1).
Meteorological
data
for
the
five
year
period
1986­
1990
were
used
for
both
domains.

The
CALPUFF
modeling
domain
is
a
subset
of
the
CALMET
domain.
For
both
domains
we
employ
a
5
grid
cell
(
40
km)
buffer
to
guard
against
edge
effects
at
the
boundaries;
this
results
in
a
520
km
x
520
km
CALPUFF
domain.
The
proto­
typical
source
to
be
evaluated
is
placed
at
the
center
of
the
domain.
Receptors
for
use
in
modeling
were
placed
in
concentric
rings
located
every
25
km
to
a
maximum
range
of
250
km;
receptors
were
located
every
10
degrees
along
each
ring.
Other
than
the
meteorology
there
are
no
other
domain­
specific
factors
in
our
CALPUFF
modeling.
Both
domains
were
modeled
in
a
flat­
terrain
mode
using
a
common
source/
receptor
base
elevation
of
200
m.
In
addition,
there
is
no
presumption
regarding
the
location
of
Class
I
areas
in
our
CALPUFF
analyses.
The
unstated
presumption,
in
the
use
of
our
results
for
BART,

is
that
all
receptors
are
located
in
Class
I
areas.

Background
Ozone
­
The
IWAQM
recommended
default
for
ozone
is
80
ppb.
The
results
presented
here
are
based
on
CALPUFF
estimates
using
a
background
concentration
of
50
ppb.

The
lower
value
better
characterizes
the
more
recent
data
for
the
National
Park
Service
monitoring
sites.

Background
Ammonia
­
The
IWAQM
recommended
default
for
forested
locations,
0.5
ppb,
was
used
for
the
eastern
domain.
The
IWAQM
recommended
value
for
arid
locations,
1.0
ppb,
was
used
for
the
western
domain.

Metric
for
Tracking
Progress
Under
the
RHR
According
to
the
Regional
Haze
Rule,
baseline
visibility
conditions,
progress
goals,
and
changes
7
)
10
/
ln(
10
ext
b
HI
=

(
)
 
dv
b
b
ext
m
ext
=
+
10
1
0
ln
_
_
in
natural
visibility
conditions
must
be
expressed
in
terms
of
deciview
(
dv)
units.
The
deciview
is
a
unit
of
measurement
of
haze,
implemented
in
a
haze
index
(
HI)
that
is
derived
from
calculated
light
extinction,
and
that
is
designed
so
that
uniform
changes
in
haziness
correspond
approximately
to
uniform
incremental
changes
in
perception,
across
the
entire
range
of
conditions,

from
pristine
to
highly
impaired.
The
HI
is
expressed
by
the
following
formula:

Here,
a
reference
extinction
coefficient
of
10
(
Mm­
1)
in
the
denominator
of
the
log
corresponds
to
a
`
pristine'
environment
and
a
haze
index
(
deciview)
of
zero.
Because
visibility
impairment
is
a
relative
quantity,
the
estimated
(
i.
e.,
modeled)
extinction
for
a
particular
source
is
not
sufficient
by
itself
to
quantify
the
perceived
effects
on
visibility
of
that
source.
This
is
because
a
given
source
impact
(
extinction)
that
may
go
unnoticed
when
viewed
against
a
hazy
background
may
be
acutely
apparent
when
viewed
against
a
pristine
background.
A
fractional
measure,
made
up
of
the
modeled
extinction
coefficient
(
b
ext­
m)
and
a
background
extinction
coefficient
(
b
ext­
0),
is
needed
to
assess
changes
in
visibility.
Two
such
measures
are
computed
and
reported
in
CALPOST,
the
fractional
(
percent)
change
in
extinction
and
the
change
in
the
haze
index
(

deltadeciview

EPA
tracks
progress
under
the
regional
haze
program
using
a
metric
for
natural
visibility
conditions
(
i.
e.,
the
goal
of
the
regional
haze
program).
This
term
is
significant
in
and
of
itself
to
the
extent
that
it
has
its
own
guidance
document.
The
following
is
from
EPA's
guidance
for
estimating
natural
visibility
conditions
under
the
regional
haze
rule.

"
The
term
natural
visibility
conditions
represents
the
ultimate
goal
of
the
regional
haze
program,
8
consistent
with
the
national
visibility
goal
set
forth
in
section
169A
of
the
Clean
Air
Act
(
CAA).

The
national
visibility
goal
is
to
remedy
existing
and
prevent
future
human­
caused
impairment
of
visibility
in
mandatory
Federal
Class
I
areas.
Regional
haze
strategies
are
to
make
reasonable
progress
towards
this
goal....
estimates
of
natural
visibility
conditions
should
reflect
contemporary
conditions
and
land
use
patterns.
That
is,
estimates
should
attempt
to
calculate
the
degree
of
visibility
impairment
that
exists
today,
given
current
vegetative
landscapes,
when
human
emissions
contributions
are
removed.....
The
1991
peer­
reviewed
report
of
the
National
Acid
Precipitation
Assessment
Program(
NAPAP)
provides
annual
average
estimates
of
natural
concentrations
for
these
six
main
components
of
PM
for
the
eastern
and
western
regions
of
the
country.
By
applying
assumptions
for
average
extinction
efficiencies
for
each
PM
component
and
for
the
effect
of
humidity,
the
NAPAP
report
also
included
estimates
of
natural
visibility
conditions
on
an
annual
average
basis.
With
minor
adjustments,
these
estimates
provide
the
starting
point
for
calculating
natural
visibility
conditions
in
the
mandatory
Federal
Class
I
areas
The
approach
to
estimating
natural
conditions
presented
in
the
NAPAP
report
defines
two
separate
regions
of
the
United
States:
(
1)
the
East,
which
consists
of
all
the
States
east
of
the
Mississippi
River,
and
up
to
one
tier
of
States
west
of
the
Mississippi;
and
(
2)
the
West
,
including
the
desert/
mountain
regions
of
the
Mountain
and
Pacific
time
zones.
Geographically,
these
two
subregions
show
strong
differences
in
haze
sources,
vegetation,
relative
humidity,
and
regional
haze
levels.
....
Table
2­
1
presents
the
default
estimated
natural
concentrations
of
the
particulate
species
for
the
East
and
the
West
along
with
estimates
of
the
dry
extinction
efficiencies
for
each
species.
These
concentration
estimates
are
used
with
the
respective
estimates
of
the
dry
extinction
efficiencies
to
establish
the
light
extinction
attributed
to
natural
sources
in
the
East
and
West."

Natural
Visibility
Conditions
Used
with
CALPUFF
Domains
With
the
information
provided
in
EPA's
guidance
for
estimating
natural
visibility,
and
with
f(
rh)

values
specific
to
the
East
and
West,
(
also
provided
in
the
natural
visibility
guidance
document)

we
have
the
necessary
information
for
calculating
annual
average
natural
visibility
conditions
for
9
the
eastern
and
western
CALPUFF
modeling
domains.
The
annual
average
natural
extinction
values
for
the
eastern
and
western
domains
are
21.2
and
15.7
(
1/
Mm),
respectively;
these
values
correspond
to
haze
index
values
of
7
.5
and
4.5
deciviews,
respectively.

RESULTS
Visibility
results
for
the
23
scenarios
are
given
in
Appendix
B.
For
each
scenario
there
is
a
table
giving
the
number
of
days
(
in
the
indicated
year)
that
a
given
delta­
dv
threshold
(
0.1,
0.5,
and
1.0)

was
exceeded
at
three
distances
(
50,
100,
and
200
km).
A
second
table
gives
the
ten
highest
delta­
dv
values
for
each
year
(
1986­
1990)
for
the
same
three
distances
(
50,
100,
and
200
km).
In
the
top
ten
tables,
a
99th
percentile
is
approximately
equivalent
to
a
value
midway
between
the
values
for
ranks
3
and
4.
Similarly,
a
98th
percentile
is
approximately
equivalent
to
the
value
associated
with
a
rank
of
7.

Caution
to
Readers
Readers
of
this
document
are
cautioned
that
it
is
not
intended
to
provide
guidance
or
recommendations
on
how
to
run
CALPUFF
for
BART.
By
their
very
nature,
illustrative
modeling
analyses
using
proto­
typical
sources
(
as
described
herein)
necessitate
a
degree
of
creativity
that
would
not
generally
be
appropriate
in
a
regulatory
application.
For
example,
a
State
will
be
modeling
a
real
source
and
will
know
the
direction
and
distance
to
the
nearest
Class
I
area;
one
would
not
expect
a
State
to
treat
the
entire
modeling
domain
as
a
Class
I
area
as
was
done
in
the
illustrative
analyses
described
here.
Although
our
procedures
included
the
use
of
default
model
options
and
switch
settings,
one
should
not
view
this
as
either
precluding
other
procedures
or
providing
guarantees
that
using
these
procedures
will
result
in
actions
that
are
fully
approvable.
