ILLINOIS POLLUTION CONTROL BOARD
February 15~ 1979
IN THE MATTER OF:
)
R75—5
PROPOSED AMENDMENTS
TO CHAPTER
)
R74-2
2,
PART II, SULFUR DIOXIDE
)
CONSOLIDATED
EMISSIONS.
OPINION OF THE BOARD
(by Mr. Goodman):
On March
7,
1974,
the Board initiated inquiry hearings,
docketed
R74-2,
into the validity
of the Air Pollution Regulations
(Chapter
2 of the Board’s Rules and Regulations)
as they pertain to sulfur
dioxide
(SO2)
emissions.
The Board conducted eight public inquiry
hearings on R74—2 throughout the State in
1974.
On December
5,
1974,
the Board ordered the Environmental Protection Agency (Agency)
to analyze two of the Board’s sulfur dioxide regulations affecting
sources outside
the major metropolitan areas
(MMA’s)
as to their
effect on air quality.
On January
9,
1975,
a Board member proposed
an amendment to Rule 204,
and the Board authorized the proposal
for hearing.
The proposal,
which was docketed number R74—2,
was
published in the Board’s Environmental Register number 97.
On March 31,
1975,
the Agency filed a proposal to amend certain
of the Board’s sulfur dioxide regulations.
The Board docketed
the proposal R75-5
and, on April
10.,
1975,
ordered that
it be set
for hearing.
The R74—2 and R75-5 proceedings were consolidated
for hearing.
The Agency
submitted revisions
to its R75—5 proposal
on April
30,
1976, August
3,
1977,
and January
6,
1978,
and the
various proposals were published in the Board’s Environmental Register
numbers
101,
120,
163 and 172.
Public hearings were held in the
following locations:
June
24, 1975
Edwardsville
June 30,
1975
Chicago
July 15, 1975
Peoria
July 29, 1975
Carbondale
August 12,
1975
Chicago
September
16, 1975
Chicago
October
21, 1975
Chicago
March 30,
1976
Chicago
May 4,
1976
Chicago
May 25,
1976
Chicago
The Board wishes to express
its appreciation for the excellent
work done in this matter by:
Roberta Levinson, Administrative Assistant
and Hearing Officer herein; Carolyn
1-Jesse, Technical Assistant;
and Ken Kirkpatrick, Administrative Assistant.
32—573
—2—
In accordance with Section
6 of the Environmental Protection
Act
(Act),
the Illinois Institute for Environmental Quality
(now
the Illinois Institute
for Natural Resources)
on November 11,
1977,
filed IIEQ Document No.
77/36,
the economic impact study of
the proposed sulfur dioxide amendments.
Economic impact hearings
were held
in the following locations:
January
10,
1978
Springfield
January
17,
1978
Chicago
The record was kept open
in this matter for 45 days after the
final hearing to allow for submittal
of public comments.
On May 11,
1978,
and again on August 24,
1978,
the Board
proposed final draft Orders which modified the Agency’s proposal
and subsequent revisions
in several respects.
Pursuant
to
Section
5 of the Illinois Administrative Procedure Act,
Ill.
Rev.
Stat., Ch.
127, §1001 et
~
the proposed final drafts were
published
in the Illinois Register on June
16,
1978 and September
29,
1978.
The public comment period extended through November
14,
1978.
Having considered the public comments
and re—examined the
record, we have modified our proposed draft Order
in certain
respects.
Based upon the voluminous record, exhibits and public
comments received,
the Board on December 14,
1978 adopted these
amendments to certain of our sulfur dioxide regulations.
Before beginning our analysis,
we note that legislation on
the state and federal
level had a significant impact on the
history and outcome of these amendments.
On the state
level,
the
Illinois legislature in 1975 amended the Environmental Protection
Act
(Act)
to include Section 10(h),
which required the Board to
adopt regulations prescribing the conditions under which existing
sources may use intermittent control systems
(ICS’s)
in lieu of
compliance with SO2 standards.
On the federal
level, Congress in
1977 adopted amendments
to the Clean Air Act,
42 U.S.C.
§7401 et
~.(1977),
many of which impose new requirements which must be
incorporated into the State Implementation Plans required by
Section 110 of the Clean Air Act.
The impact of both
of these
pieces of legislation will be discussed
in the course of this
Opinion.
HISTORY OF THE REGULATIONS
Section
109 of the Clean Air Act as amended
in 1970 required
the Administrator of the United States Environmental Protection
Agency to promulgate primary and secondary national ambient air
quality standards
(NAAQS) for certain pollutants,
including
sulfur dioxide.
The primary national ambient air quality
standard
is defined as the standard requisite
to protect the
public health.
The U.S. Environmental Protection Agency
32—574
—3—
promulgated a primary annual 502 standard of
89 uq/m3(0.03 ppm)
and a short term
(24 hr.)
standard of 365 ug/m
.
The Board
adopted primary ambient air quality SO2 standards identical
to
these federal standards
in Rule 308 of Chapter
2.
Section 110 of
the Clean Air Act requires each state
to submit to the U.S.
Environmental Protection Agency
a State Implementation Plan
(SIP)
which includes emission limitations insuring attainment and
maintenance of the NAAQS.
The Clean Air Act as
amended in 1977,
in Section 107(d)(1),
requires each State to identify which air quality control regions
or portions thereof in the State do not meet a national primary
air quality standard for SO2.
For those areas designated
non—attainment,
the State must by July
1,
1979,
revise its SIP to
assure attainment
of the SO2 standard by December 31,
1982.
For
those areas designated attainment, Part C of the Clean Air Act,
entitled “Prevention of Significant Deterioration of Air
Quality,” applies.
The Board notes that the portion of the State
covered by these amended regulations
includes only one designated
non—attainment
area, Massac County
(43 Federal Register 8987—8988
(March
3,
1978)).
In 1972, the Board adopted its Air Pollution Regulations,
which were submitted by the Illinois Environmental Protection
Agency to the U.S. Environmental Protection Agency and approved
as Illinois’
State Implementation Plan.
Included
in those
regulations was Rule 204(e),
which provided a formula by which
owners
of
fuel combustion sources were to determine the total
amount of SO2 per hour which could be emitted from all sources
owned by them and located within a one-mile radius.
The formula
was aimed
at preventing violation of the short—term sulfur
dioxide standard.
The Air Regulations also included Rule
204(c)(1)(B), which required sources located outside the Chicago,
Peoria and St. Louis
(Illinois) MMA’s to meet an emission
standard of
6.0 pounds of SO2 per million btu of heat input.
This standard was based upon the washability of Illinois coal and
was aimed at eliminating easily avoidable emissions
at relatively
low cost.
See
In the Matter of Emission Standards,
R71—23,
Opinion of the Board,
4 PCB 298
(April 13, 1972).
The regulations adopted by the Board herein amend both Rules
204(e)
and 204(c)(1)(B)
as well
as adding new paragraphs
to Rule
204.
Rule 204(e) has been limited to sources outside the
Chicago,
St. Louis
(Illinois)
and Peoria MMA’S and the formula
has been amended
in Rule 204(e)(1)
to more accurately correlate
allowable emissions with prevention
of
the short—term ambient air
quality standard.
The Rule 204(e)(1)
formula is based
on a
conservative set of worst—case meteorological and physical
parameters.
However, because these assumptions may be overly
conservative for some sources,
we have provided a mechanism in
Rule 204(e)(3)
whereby a source may determine
its own alternate
emission limitation through
a program of modeling and monitoring
its emissions.
Rule 204(e)(2)
retains the old mass emission
limitation and “grandfathers in” those sources which have in
good
faith complied with the old formula but would have been thrown
32—575
—4—
into non-compliance with the new formula.
Finally,
although the
new formula and the alternate emission limitation provision could
in some cases allow sources
to increase their emissions to a
level above that allowed by the old formula,
no source may do so
without first proving
it will not violate the prevention of
significant deterioration increment
(PSI) Increment) determined by
Section 163
of the Clean Air Act and Regulations adopted
thereunder.
Also, Rule 204(1)
precludes any source from meeting
the Rule 204(e) formulas by the use of dispersion enhancement
techniques.
The Board has eliminated the prior Rule 204(c)(1)(B)
requirement that the sources
located outside the three
large
MMA’s,
in addition to meeting the mass emission limitation, meet
a 502 standard of 6.0 lbs./MBTU.
However,
sources burning
less
than 250
MBTIJ have been given their choice of complying with the
Rule 204(e) formulas or a standard of
6.8 lbs./MBTU.
ANALYSIS OF THE REVISED REGULATIONS
During the hearings, Gary Melvin of the Agency testified
that in his opinion the new formula found
in Rule 204(e)(1)
protects the short—term standards better than the old formula
(R.123)*, which “...has technical inadequacies and ignored
certain site—specific information”
(R.1011).
Although there are
differences between the old and the new formulas for determining
a source’s mass emission
limitation, they do have several points
in common.
Both formulas are based
on the Gaussian dispersion
equation for point sources, which has been generally accepted to
adequately describe dispersion over short distances
(Ex.
5,
ref.
29). Both formulas also average all the stacks within
a one—mile
radius of the center of the source,
as though all the emissions
from the source were from one stack.
Since the purpose of Rule 204(e)
is to protect the
short—term ambient air quality standards,
adverse meteorological
conditions which could
lead to violations of the short-term
standards are used
in the derivation of the formulas.
According
to Agency witness Melvin,
the old formula
(now in 204(e)(2))
was
presumably derived in order to protect the 3—hour secondary
sulfur dioxide standard
(Ex.
4,
ref
3).
Unstable stability
conditions and
a reference windspeed of 6.56 feet per second,
(2
meters per second), which did not vary according to stack height,
were used.
Trapping conditions due
to an inversion were not
assumed.
The new formula in Rule 204(e)(1) was derived to
protect the primary 24—hour SO2 standard during the following
“worst—case” meteorological conditions
(R.78):
*
All references
to exhibits and pages
in the record will
refer to R75—5,
unless R74-2
is
specified.
12—576
—5—
1.
The plume from the source
is trapped between the ground
and
a stable
layer aloft
such that
the
height of the
inversion base
(lid)
is equal to the effective
stack
height.
(The effective stack height
is equal
to the
sun of the actual
stack height and the height of the
plume rise;
it
is
the
height
at which the plume
essentially becomes level.)
In general, trapping
conditions with
the height of the inversion lid equal
to the effective stack height would be the most
restrictive since these conditions would allow the
least amount of vertical mixing.
If the lid were
situated above the effective stack height,
the mixing
depth would he greater and, consequently,
concentrations of pollutant would be
less;
if the lid
were situated well below the effective stack height,
the plume could punch through the
l.id
and be held aloft
by the inversion
layer and not touch the ground.
2.
Class B stability
(unstable)
is assumed to occur below
the inversion.
Although class D stability (neutral)
is
much more prevalent during limited mixing situations,
class
B stability can occur and would result in higher
ground level concentrations due to uniform vertical
mixing occurring closer to the source.
3.
The average surface wind speed is equal
to 14.44
feet/second
(4.4 meters/second
(mis))
at
a height 32.81
feet
(of
10 meters) and varies according to the
following power
law, which provides for increases
in
wind speed as stac~~ight
increases:
U=U3281(HA/32.8l)
,
where
U
average wind speed
at stack height HA,
in feet,
and U32 81=14.44 feet/sec.
(U= Ulo(HA/i0)O
L, where U
=
average wind speed
at stack
height HAl
in meters,
and U10
=
4.4 m/s).
4.
Persistent plume trapping occurs for six hours which
would result in a maximum hourly SO2 concentrati~n,
which should not be exceeded, equal
to 1q60 ug/m
(micrograms per3cubic meter).
(365 ug/m
x 24 hr.
~
6
hr.
=
1460 ug/m
)
Meteorological data collected at Springfield, Moline, and
Vandalia indicate that unstable atmospheric conditions with
persistent winds
(for
6 hours or more)
at a given compass point
occur from
0 to
5 times per year
(R.80).
Hence,
the new formula
may be considered to be conservative
in the sense that there are
more prevalent meteorological conditions than those which it
assumes
(R.86).
However,
it should be noted that
in order to
protect a short—term standard,
the worst—case conditions,
which
may give rise to violations, even though
infrequent,
should be
considered.
32—577
—6—
The old and the new formulas also differ with respect
to the
site—specific parameters which are used
in calculating a given
source’s emission limitation.
The new formula utilizes the
following weighted—average
stack parameters which are specific to
that facility:
stack diameter,
exit velocity of stack
gases,
exit temperature of stack gases,
and actual stack height.
The
weighting factor for
a given stack
is based on the percentage
of
total emissions that are emitted from that stack.
For example,
if a source has two stacks with stack A emitting 40
of the
source’s emissions and stack B emitting 60,
then the stack A
parameters would be weighted by a factor of 0.4 and the stack B
parameters would be weighted by a
factor of 0.6.
The firing rates to be used for determining the weighting
factor
P,
exit gas temperature T,
and exit gas velocity V are
based on the boilers’
name plate ratings
(R.2115), which are the
operating conditions that presumably result
in maximum emissions.
In the old formula, on the other hand,
the average actual stack
height was the only site-specific parameter used.
(The stack
heights were weighted by percentage of total emissions.)
The
allowable emissions from a given source were obtained through a
comparison of
the average actual stack height of that source with
the average actual stack height of a reference source for which
an allowable emission limitation had been calculated.
The
reference stack had the following parameters:
an actual
stack
height equal
to 300 feet,
an exit gas temperature equal
to 500°F,
a stack diameter equal to
7
feet,
and an exit gas velocity equal
to 60 feet/sec.
(Ex.
4,
ref.
3).
The old and the new formulas also utilize different plume
rise formulas for calculating the height that the plume rises
from the top of the stack before leveling.
The new formula
utilizes the “2/3 power
law” formula developed by Briggs and
promoted by the U.S. Environmental Protection Agency
(Ex.
4,
ref.
9,
p.
15). Although
no one plume rise formula applies to all
conditions,
“buoyant plumes have been found
to follow the 2/3 law
for transitional rise for considerable distance downwind,
regardless of stratification”
(Ex.
5,
ref.
30,
p.
57).
Several
references
(Ex.
5,
ref.
30; Ex.
4,
ref.
16; Ex.
4,
ref
9;
Ex.
5,
ref.
31) noted that the bulk of plume rise data fit this formula.
However,
it should be noted that the Briggs formula tends to
over—predict plume rise for large stacks and consequently
underestimates ground—level concentrations
(Ex.
4,
ref.
5). The
old formula does not utilize the Briggs plume rise formula.
It also appears that the Briggs formula
is more accurate for
facilities that have
a single stack than for facilities that have
multiple stacks near each other.
During one experiment to verify
the plume rise formula,
it was found that during stable
conditions the observed plume rise from two nearby stacks was
somewhat greater than the plume rise that would occur from the
stacks individually or for a calculated average stack, weighted
by the SO2 emission rate
(Ex.
4,
ref.
14,
p.
1051).
32—578
—7--
Neither the old nor the new rule provide for background
concentrations of sulfur dioxide
(R.86).
For more detail
on the
derivation of the old and the new formula,
see reference
3
of
exhibit
4 and reference 26 of exhibit
5,
respectively.
Various witnesses testified as
to shortcomings of the new
formula.
Most of the criticism was directed at modeling
emissions from numerous stacks
as
if they came from one stack
with parameters
(e.g.
height, diameter) equal
to the average of
the parameters
from the other stacks.
In particular, Kontnik and
Davidson, testifying for the U.S. Industrial Chemical Company,
argued the formula in Rule 204(e)(1)
does not model
the effects
of multiple sources realistically (R.443).
They testified that
when multiple stacks are involved,
each site must be considered
individually so that the following characteristics can be
considered:
three—dimensional spacing of each source
(vertical
and horizontal spacing), heat contents of the plumes and any
structures that are near the stacks
(R.444).
For example,
the
plumes from a tall
stack with a large plume rise and a short
stack with a small plume rise may never interact
(R.446).
T.J.
May, testifying for Illinois Power (starting on R.683),
stated that the proximity of the three tall stacks
at
a plant
like the Baldwin Plant could
lead to enhanced plume rise.
This
would be due to the hot flue gases combining and tending to
reduce the total amount of air to flue gas interface,
which would
reduce plume cooling, allowing higher plume rise and increased
dispersion.
Polcaliyka,
with Sargent and Lundy,
also testified for
Illinois Power that the method of converting
all stacks within a
one—mile radius into
a single average stack
is overly
conservative
(R.694).
In particular,
he stated that the
worst—case meteorology
for stack A is not necessarily the
worst-case for stack B and will not be the worst—case for the
average stack derived from stacks A and B.
According to this
witness,
in order to be fair and realistic
in a multiple stack
situation,
one must consider the distance between stacks and
their alignment with respect to each other and the prevailing
wind direction.
For example,
he recommended that,
if the stacks
are separated by large distances and/or are dissimilar
in design,
each stack be considered separately and the ground—level
concentrations be added.
On the other hand,
if the stacks are
close enough together to get plume interaction which would
involve increased plume
rise,
that condition should be considered
also.
It was also pointed out by Fancher of Commonwealth Edison
(starting on R.1093) that for some sources, especially short
sources,
plume trapping by an inversion may not be the worst—case
condition.
Plume coning,
looping,
inversion break—up and
fumigation may result in higher ground—level concentrations.
Another weakness in the new formula is that
it assumes that the
maximum emission rate results in maximum ground—level concentrations,
which is not always true
(P.C.
#52).
32—579
—8—
Despite the Board’s recognition that the Rule 204(e)(1)
formula may indeed have certain shortcomings, the Board finds
that
it
is
a state—of-the-art formula and describes the
worst—case
(most restrictive) meteorological conditions for many,
though not all, sources.
However,
sources who are able
to prove
to the Board
that operating,
meteorological,
and/or plume
dispersion conditions other than those found in Rule 204(e)(1)
would be the limiting worst-case conditions may obtain a
site—specific alternate emission limitation pursuant to Rule
204(e)(3).
In addition,
sources who by April
1,
1978,
complied
with the old formula but do not comply with the new Rule
204(e)(1) formula, may continue to comply with the old formula,
pursuant to Rule 204(e)(2).
As stated,
in order for a source
to qualify for a Rule
204(e)(3) alternate emission standard,
it must prove
site—specific limiting worst—case conditions different than those
in Rule 204(e)(1).
An example of a situation
in which an
alternate operating condition could be more appropriate would be
a common stack servicing several units.
Under high volume
conditions,
it may perform well
(R.703).
However,
if the load is
reduced to
30,
the stack may not function as well due to a
decrease
in exit gas volocity which would cause
a decrease in
plume
rise and may
lead
to downwash.
Since large isolated sources may not threaten the annual
standard but may cause short—term elevated concentrations due to
fumigation,
high winds,
limited mixing, atmospheric stagnation,
and/or poor stack design,
modeling emissions under those
conditions is essential
(R.
1584).
In determining an alternate
emission limitation,
the following adverse meterorological
conditions should be considered,
unless
a facility has monitored
the site—specific meteorological conditions for at least three
years
(in that case,
the most adverse meteorological conditions
for that site should be modeled
(Ex.
64):
1.
Trapping conditions with the mixing height equal
to the maximum height of plume rise,
wind speed
equal to 14.44 ft./sec.
(4.4 m/s)
at a height of
32.81
ft.
(10 meters)
above ground level,
and
atmospheric stability equal
to B
(unstable).
2.
Neutral stability with moderate to high winds
(at the
wind speed which produces the maximum ground—level
concentration),
mixing height equal
to 3937
ft.
(1200
meters) and stability class
equal
to
I) (neutral).
3.
Atmospheric stagnation with the mixing height equal to
1640 ft.
(500 meters,) atmospheric stability equal to D
(neutral),
and the wind speed equal
to 4.43 mi./hr.
(2
m/s)
at a height of 32.81
feet
(10 meters) above
ground—level.
32—580
—9—
4.
Inversion break-up fumigation with the mixing height
located at ground-level
at the beginning of the
three—hour period, rising
at a rate of 16.01 ft./min.
(4.88 meters/minute);
an atmospheric stability class of
E
(stable)
above the height of the inversion and B
(unstable) below the inversion; and a wind speed of
14.44 ft./sec.
(4.4 m/s)
at a height of 32.81 feet
(10
meters) above ground—level.
5.
Any other meteorological conditions experienced in the
vicinity of the subject facility which might reasonably
be expected to produce maximum ground—level SO2
concentrations in excess of those calculated under the
above four conditions.
In all cases,
background concentrations of
SO.)t
which are
contributed by other sources,
should be considered, and the
calculations should be made with the wind from the direction
which would align the emission sources to maximize the
ground—level concentration for the actual source configuration.
In determining an alternate emission formula,
it
is
necessary to model emissions and monitor the ambient air qualtiy
in the vicinity of the source in question.
Modeling is necessary
because it
is impractical
to have enough monitors
in the vicinity
of the source to be confident that all violations are identified
(R.1446).
Monitoring data is essential
in order
to validate and
calibrate the model being used.
Rule 204(e)(2) “grandfathers
in” sources who had come into
compliance with the Rule 204(e)
formula in effect prior to these
amendments but who are not in compliance with the new formula.
Because the Board has determined that
it
is economicailly
unreasonable to require such sources
to spend the additional
funds necessary to meet the new formula
(see the discussion on
“Technical Feasibility and Economic Reasonableness”),
we have
allowed such sources to choose between the two formulas.
As noted
previously, all areas
of the state covered by Rule 204(e),
with
the exception of Massac County, have been designated as having
attained the ambient air quality standards for SO2
(43 Federal
Register 8987—8988
(March
3,
1978))
(or have been designated as
“cannot be classified”).
Allowing sources who have met the old
standard to continue
to meet that standard should not,
therefore,
prevent maintenance of the standard.
Nevertheless,
the Board
notes that Rule 102 prohibits any source from preventing the
attainment or maintenance of any applicable air quality standard,
regardless of whether the source
is in compliance with a specific
emission limitation.
Rule 204(i) prohibits sources from complying with the mass
emission limitations determined by Rule 204(e)(1),
(2), or
(3) by
means of dispersion enhancement techniques,
which the Rule
defines generally.
Such techniques merely dilute the emissions
over
a
larger area without actually decreasing the emissions.
Prohibition of dispersion enhancement techniques as
a means
of
complying with an emission limitation
is specifically mandated by
Section 123
of the Clean Air Act Amendments of 1977.
:32—581
—10—
All sources located outside the three largest MMA’s were
previously required to comply with
a pounds per million btu SO2
standard of 6.0
in addition to the pounds per hour standard
determined by Rule 204(e).
As mentioned previously,
this rule
was based on the washability of Illinois coal.
This requirement
has been eliminated because the record indicated
it is not
technically or economically feasible for all sources to meet the
standard by washing Illinois coal
(R.8,
Ex.23; R74—2,
R.1504).
However,
the Board has retained
a pounds per million btu standard
of 6.8
for small
sources
(with heat
input
less than 250 MBTU/hr.)
and has allowed such sources
to choose between this
limit and the
pounds per hour standard determined by Rule 204(e).
Changing the
standard from 6.0
to
6.8 lbs./MBTU approximately doubles the
amount of Illinois coal that can be burned without control and
still meet the standard
(R74—2, Ex.56(c)).
Considering the minor
impact of these sources and the general attainment of the SO2
ambient standards
in the areas involved,
this change should not
affect air quality.
Each of the Agency’s proposals included a rule which would
have prohibited sources from increasing their emission
rate
beyond the existing rate
as of the effective date of the
regulations.
This rule was referred to as the “cap rule” because
it “capped” emissions at current levels.
The version of the cap
rule included in the January
6,
1978,
Agency proposal would have
required that any source which increased its firing rate or
emission rate after
the effective date
of
the Rule be considered
a modified source
and,
thus,
subject to new source performance
standards.
Industry representatives expressed opposition to this
proposal
(R.2130,
2143—2149,
2199—2201).
The Board finds that
there
is
insufficient support
in the record to prove that such a
restrictive provision is necessary to protect air quality.
We
have not,
therefore,
included a “cap” provision in the adopted
regulations.
However,
as mentioned previously,
Section 163 of the Clean
Air Act as amended
in 1977 requires that for any given area the
maximum allowable increase in concentrations of SO2 over the
baseline concentration of 502 not exceed a certain amount,
commonly known as the PSD increment.
The U.S. Environmental
Protection Agency,
the Agency and Commonwealth Edison Co.
expressed concern in public comments
(P.C.
#‘s
52,
51 and
42,
respectively) that the proposed regulations could
in some cases
allow sources to increase emissions and, therefore, possibly
violate the
PSI) increment.
Three
rules which could conceivably
result in increased emissions are the new Rule 204(e)(1) formula
(see Ex.
25),
Rule 204(e)(3)
and the 6.8 lbs./MBTU optional
standard for sources burning less than 250 MBTU/hr.
Rule
204(e)(3) includes a requirement that sources seeking an
alternate standard prove that
they will not violate the
PSD
increment.
We have also included in our adopted regulations Rule
204(e)(4),
which precludes sources complying with the Rule
204(e)(1) formula or the 6.8 lbs./MBTU standard from increasing
emissions without first obtaining a new operating permit from the
32—582
—11—
Agency based on an application which proves that the PSI)
increment will not be violated.
The Agency shall have the
authority,
as
it does
with
other permit applications,
to
determine the details of what such an application should include.
The Board notes that this record does not provide
a basis for
determining a method of allocating the increment among sources.
INTERMITTENT CONTROL SYSTEMS
As mentioned previously,
the Illinois
legislature
in 1975
amended the Environmental Protection Act to include Section
10(h),
which requires the Board to adopt regulations prescribing
the conditions under which sources may use intermittent control
systems
(ICS’s)
in lieu of compliance with
SOT, standards.
An ICS
is a system whereby
a source determines, hase~on modeling and
monitoring,
the conditions
under which air quality violations may
occur.
The source adopts
a strategy such as
fuel switching,
load
reduction,
or temporary shutdown to prevent
the occurrence
of a
predicted violation.
The Agency’s original proposal
in P75—5
included an extensive ICS provision allowing existing sources
located outside the three MMA’s
to use an ICS,
under certain con-
ditions,
for several years
in lieu of compliance with specific
SO2 standards.
Much of the testimony and exhibits submitted at
the hearings focused on the merits of ICS (R.589—529,
745—811,
966—986, 933—1036,
1363,
1387,
1396—1418,
1471—1473,
1545—1556,
1656, Exs.29,34,65).
The Clean Air Act Amendments of 1977,
adopted after these
proceedings were well under way,
specifically prohibit the use of
intermittent control
systems as a method of compliance with
emission limitations.
Section 123
of the Clean Air Act
specifically defines intermittent control systems as dispersion
enhancement techniques,
which,
as has been discussed,
cannot be
used to comply with emission standards.
The Agency,
therefore,
in its January
6,
1978,
revisions proposed a much abbreviated
version of the ICS rule which would have provided for use of an
ICS only
in addition to constant emission controls and as
a
result of a Board Order or a condition attached by the Agency to
the source’s permit.
Industry representatives expressed
opposition to this proposal
(P.214,224).
In the Board’s final Order, we have eliminated the ICS Rule
entirely and have,
in accordance with Section 123 of the Clean
Air Act,
defined ICS as a dispersion enhancement technique.
The
change was in large part based upon a comment by the U.S.
Environmental Protection Agency
(P.C.
#52) which indicated that
ICS was impermissible, even in addition to constant controls,
if
it was used as
an aid to achieve
an ambient air quality standard.
The Board could,
of course,
in a compliance order in a situation
where constant emission controls have not been installed order
the operation of an ICS in the interim period.
32—58:3
—12—
ECONOMIC
IMPACT
STUDY
(STUDY)
The Study that was
filed with the Board
(Ex.90)
analyzed
part of the proposed regulation.
Specifically, the Study
examined both the current and
(then) proposed mass emission
limitations,
the six—pound standard of old Rule 204(c)(l)(B)(i),
and the proposed “cap rule”
(Ex.
90,
pp.
1-4).
The Study’s
analysis did not consider intermittent control systems,
the pro-
hibition on the use of dispersion enhancement techniques,
or the
provision for a determination of
a site-specific emission
limitation.
Also not considered were the “grandfathering”
provision and the change
for small
sources
(Rule 204(c)(1)(B)).
Because of
the discrepancy between what was analyzed
and what was
adopted, many of the findings of
Lhe Study do not apply to the
adopted regulation.
However,
the findings did present some
implications
for what was proposed at
the time and were of use to
the Board in its analysis.
The study initially examined
54 sources; thirty—six
sources
were determined
to comply with both the existing and proposed
mass emission limitations
(R.l962).
The incremental costs and
benefits
of the proposed regulation were designated
as zero for
these 36 sources
(Ex.
90,
p.51).
The Board,
however, recognizes
that there may be some loss of flexibility for these sources.
The remaining
18 sources were examined in some detail.
Estimates of control costs were made, although the author of the
study emphasized that these costs should be viewed in the
aggregate and not
as site-specific approximations
(P.1970).
Furthermore,
these estimates of control costs do not consider the
possibility of combining two or more control stràgegies
(Ex.90,pp.56—7).
It
is clear that
the greatest impact was
determined to be additional
control costs for sources which
complied with the existing
emission rate hut not the proposed
rate (P.1976; Ex.99;
Ex..90,
p.58, Table
46).
Since the rule as
adopted “grandfathers in” these sources, as well
as sources which
were
in compliance with
a F3oardOrder as of April
1,
1978,
they
will not incur any additional control costs.
The author of the
Study concluded that
“.
.
.if those sources that are already in
compliance with current emission limits are exempt from the
proposed revisions of proposed amendments,
then the two
—
the
current and the proposed regulations
—
are almost identical,
economically”
(P.1976).
Some sources which,
due to
non-compliance with the old emission limitation,
are not
“grandfathered” may be
required to control
to a greater extent
under Rule 204(e) (1) than under Rule 204(e) (2);
other sources may
have
a looser emission limitation under 204(e)(1)
than under
204(e)(2).
To sources which would have a tighter limitation
under Rule 204(e)(1), additional
costs may be incurred
(Ex.99;
Ex.90, p.58, Table 4—6).
Benefits were examined by using a damage function to express
the effects of sulfur dioxide levels in monetary terms.
The
damage function considered changes in mortality rates, morbidity,
32—584
—13—
materials
soiling and corrosion,
and crop yields; changes
in
aesthetics,
visibility,
animal mortality and morbidity
(Ex.90,
p.
ix), corrosion to certain industrial and commercial equipment,
damages
to works
of art,
and damage
to goods
in retail stores
were not considered
(P.2298).
The monetary calculations were
based on dispersion modeling predictions
of ambient SO2 levels
under the different emission limitations.
The sources that are
“grandfathered” will
not reduce emissions,
and there will be no
increase in benefits due to lower ambient SO2
levels.
Sources
which
do increase emissions will effect a lowering
in ambient SO2
levels, and some benefits will accrue
(Ex.99;
Ex.90, p.58).
Rule 204(e)(3)
introduces
additional
uncertainty into the
economic analysis.
Since
a source might obtain a site—specific
emission limitation which
is
less stringent
than the emission
rate modeled in the Study,
the control costs and monetized
benefits could differ significantly from those predicted.
However, despite the limitations of the study,
the Board finds
that the proposed regulation will not have
a significant adverse
economic impact on the people of the State of Illinois.
TECHNICAL FEASIBILITY AND ECONOMIC REASONABLENESS
Section
27(a)
of the Environmental Protection Act requires
that,
in promulgating substantive regulations,
the Board take
into account the technical feasibility and economic
reasonableness
of measuring or reducing the particular type of
pollution regulated,
in this case SO2.
In order to assess the
technical feasibility and economic reasonableness
of the
regulation,
we must examine what the impact will be on the
sources
it
is
intended to regulate.
Exhibit
25 of P75—S
lists
17 power plants and 31 industrial
fuel combustion sources which are affected by this rule change.
For each source,
the exhibit contains the generating capacity,
firing rate,
calculated maximum emissions,
allowable emissions
under the old Rule 204(e),
and allowable emissions under new Rule
204(e)(1).
Although the list does not include
all, affected
sources and may no longer
be totally accurate due to possible
changes
in coal supply or other conditions,
it has been useful in
arriving at
a very rough estimate of the impact of the adopted
regulations.
(The Agency submitted an updated version of this
exhibit
in public comment
#51).
Exhibit
25
indicates that
36 sources are already complying
with the new,
in some cases
tighter, emission
limitation.
Such
sources must continue such compliance.
Voluntary compliance to
this degree
is
indicative of both the technical feasibility and
economic reasonableness
of this level
of control
for these
sources.
Some
loss of
flexibility may result,
since these
sources
no longer have the option of emitting at levels allowed
under the old emission limitation; however,
this loss of
flexibility does not render control at the existing level
32—585
—14—
unreasonable.
We note that several
sources will be allowed to
increase their emissions under
the new formula and will,
if they
intend to increase
them beyond the
level allowed under the old
formula, have to prove in
a permit application that
the emissions
will not violate the applicable
PSI) increment.
Approximately
5 power plants and
4 industrial
sources were,
according to Exhibit 25,
in compliance with the old emission
limitation,
now
in Rule 204(e)(2),
but are not
in compliance with
the new emission limitation
found
in Rule
204(e)(1).
The author
of the economic impact
study found
that
the additional costs for
bringing such sources into compliance with the new rule,
compared
to the benefits derived from compliance,
resulted
in costs
from
the Agency’s proposal exceeding benefits.
Exhibits
90 and
99
provide estimates of control costs.
Concern about these
additional expenditures was expressed
at
the
hearings
(R.191).
Although the Board
finds
that there are limitations
inherent in
these estimates,
we find that the record
in this matter indicates
that
it
is economically unreasonable
to require sources which
have already spent the funds necessary to comply with the old
formula
to spend significant additional
funds
to meet the new
formula, particularly in light of the fact that the old formula,
though no longer state-of—the-art, was based upon maintaining
ambient air quality and that ambient air quality standards for
SO2 have generally been attained.
Hence,
Rule 204(e)(2) now
“grandfathers in” these sources by allowing them to choose
between continuing to meet the old limitation or reducing
emissions
further and meeting
the new limitation.
Two of the
17 power plants and
18
of the
31 industrial
sources
listed in Exhibit
25 have firing rates of less than 250
MBTU/hr.
and thus under Rule 204(c)(1)(B) would be eligible to
choose between the 6.8
lbs.
of
S02/MBTU
standard and the pounds
per hour standard determined by Rule (204(e).
All
20 of these
smaller sources should he able to meet the 6.8 lb.
rule by using
coal benefication (coal
“washing”),
which was discussed fairly
extensively in the record
(R.465—477, 478—493,
Exs. 22,23,19 and
31; R74—2,
Ex.56).
In fact,
calculations based upon information
in the record indicate that half of the Illinois coal for which
we have test results available could meet this limit without
washing
(Ex.23;
R74—2,
Ex.56(c)). Even so,
according to Exhibit
25,
for
9 of
these
18 industrial
sources and both the power
plants Rule 204(e)(1)
is less restrictive than the 6.8 lbs./MBTU
rule.
Our decision to allow such sources
to choose between the
standards
is based upon
a determination that
it
is economically
reasonable to give some leeway to them
in light of their
relatively minor impact on air quality in the areas involved,
since these areas
are not highly industrialized and have
generally achieved attainment of the SO., ambient air quality
standards.
We again note that sources that elect the 6.8
lb.
limit
as their standard
must
apply for a permit and
prove
they
will not violate the PSD increment
if they intend to increase
emissions beyond the
limit allowable under the old Rule 204(e).
32—586
—15—
Finally,
exhibit
25 indicates that only seven out of
17
power plants and four out of 31 industrial sources will in effect
have to reduce emissions or prove that an alternate emission
limitation under Rule 204(e)(3) would he more appropriate. These
numbers may be overestimates since some of these facilities may
have become eligible for “grandfathering”
since exhibit 25 was
prepared.
In addition,
at
least one power plant has already been
granted a site—specific emission limitation.
Illinois Power
Co.
v.
EPA, PCB 79—7.
Because these sources have been operating
in violation of the old rule,
the Board need only consider the
technical feasibility and economic reasonableness
of
requiring
such sources
to reduce their emissions by the additional amount
required by Rule 204(e)(l) over and above that which was required
by the old Rule
204(e).
The precise amount
of additional control
required varies from source
to source.
In some cases,
the new
formula may be less restrictive than the old.
We find that the
record indicates that,
for sources for whom the new rule
is more
restrictive than the old,
requiring
the additional control
necessary to meet the new Rule 204(e)(1)
is economically
reasonable
(Ex.90,
p.58; Ex.99).
Furthermore,
the record
indicates numerous methods for reducing sulfur dioxide emissions,
including the use of
low sulfur western coal or Illinois coal
which has been beneficiated or “washed” as discussed above or the
reduction of sulfur dioxide
in the flue gasses by any of several
methods which we find are demonstrated and available.
These
methods include lime/limestone scrubbers,
double alkali systems,
magnesium oxide and catalytic oxidation (R.311—3l3,
321—24,
838—906,
1101—1316,
1329—1360,
Exs.
11,58,71,79,81; P74—2,
418—425,
474—485,
630—653,
1276—1281,
1289—90,
1614,
1617—1651,
2338—2343,
Exs. 38,40,42,69).
We find that the additional degree
of emission control required by Rule 204(e)(1)
for some sources
is technically feasible.
We have considered the impact of these regulations on the
affected sources.
Based upon the information developed in the
record herein, we conclude that these regulations represent a
technically feasible and economically reasonable approach to
controlling sulfur dioxide emissions.
32—587
—16—
RULE—BY—RULE-EXPLANATION
Rule 101:
Definitions
We have added a citation to the Clean Air Act and a
definition of
“PSD
Increment”
to Rule 101.
The PSD Increment
definition
is intended to correspond to the definition determined
by Section 163
of the Clean Air Act and implementing regulations.
Rules 204(c)(l)(B),
(C), and
(D)
Rule 204(c)(1)(B)
as adopted provides
a choice for existing
fuel combustion emission sources with actual heat input less
than,
or equal
to, 250 million BTU per hour located outside the
Chicago,
St. Louis
(Illinois),
and Peoria major metropolitan
areas.
These small sources may choose an emission limitation of
6.8 lbs./MBTU or the pounds per hour emission limit provided by
Rule 204(e).
These smaller sources are subject to Rule 204(eJ(4
which prohibits any increase
in total emissions over the level
allowed by the previous Rule 204(e) unless the source obtains
a
new operating permit and demonstrates that no applicable PSD
increment will be violated.
Rule 204(c)(1)(C)
requires sources with heat input greater
than 250 MBTU/hr.
to meet the Rule
(204(e)
formula.
Rule
204(c)(1)(D)
is merely a renumbering of what was Rule
204(c)(l)(B)(ii).
The Board has proposed deletion
of this Rule
in a separate proceeding,
docketed P78-17.
Rule 204(e)
Rule 204(e) previously applied to fuel combustion emission
sources statewide.
It has been rewritten to apply only to
sources outside the Chicago,
Peoria and St. Louis
(Illinois)
MMA’s.
Because the Rule
204(e)
formulas contain no provisions
for concentrations of
SOp) from multiple sources
(P.86), the
formulas would not be sutficient
to prevent violations
of ambient
air qualtiy standards in the highly industrialized Chicago,
St.
Louis and Peoria metropolitan areas.
We
note that the Rule
2O4(e) formulas apply
to both new and existing sources but that
new sources must also meet New Source Performance Standards.
See
R78—18, Resolution and Order of the Board, December
14,
1978.
The basis for adopting
a revised formula has been discussed
previously.
However, certain details of the wording of Rule
2O4(e)(1)
require explanation.
Rule 204(e)(1)
includes a
definition of each of
the variables used
in the formula.
“II”
is
defined
as physical stack height
in
feet.
However,
the value
used for “H” in the formula cannot exceed good engineering
practice as defined by Section 123 of the Clean Air Act and
implementing regulations unless the source demonstrates that
a
greater height
is
necessary
to
prevent
downwash or fumigation
conditions.
The term “good engineering practice” when applied to
32—588
—17—
stack heights generally means that the stack is tall enough to
prevent downwash of the plume due to eddies
in the lee of the
building or from other nearby obstructions
(Ex.
4,
ref.
9;
Ex.
5,
ref.
24).
The general rule of thumb
guide for stack heights
is
that the stack should be from 1—1/2
to 2-1/2
times the height of
the nearest obstruction,
depending on the building’s dimensions
(Ex.
5,
ref.
30).
Exact details of maximum allowable stack
heights,
in accordance with the Clean Air Act Amendments of 1977,
have been proposed by the U.S. Environmental Protection Agency.
44 Fed.Reg.2608—2614
(January 12,
1979).
Two signs
of poor stack
design (too short)
are that a substantial portion of the upper
end of the stack
is blackened by soot or the plume centerline
is
continuously observed to slope downward
(R.75).
(For additional
discussion of stack heights see testimony starting on R.1855 and
Ex.
46).
Although the Agency’s proposal specified that stack
height up to 2—1/2 times the height of the nearest obstruction
could be used as the value of
“H”,
we have directly defined
allowable stack heights in accordance with the Clean Air Act and
Regulations adopted thereunder because
in some cases
a stack
height value of less than 2—1/2
times the nearest obstruction may
he required.
We note that the values used for exit temperature,
exit velocity and percentage of total emissions are to be those
which occur during operating conditions which would cause maximum
emissions.
Finally, Rule 204(e)(1)
as adopted differs from the
proposed rule in that
it has been written in the English rather
than the metric system.
Rule 204(e) (2), the “grandfather” provision,
allows sources
in compliance with the old Rule
204(e) but not in compliance with
the new Rule 204(e)(1)
to choose between the two formulas.
A
recent past date
(April
1,
1978) was chosen as the date for
compliance with either the old standard or a Board Order so that
only sources which had complied
in good faith,
and not at the
last minute
in order to receive a lower standard, would be
eligible.
Furthermore, the phrase “during normal cyclical
variations
in firing rate and fuel” has been used to describe the
conditions
under which a source must be unable to comply with the
Rule 204(e)(1) formula in order to qualify for Rule 204(e)(2).
Recognizing that firing rate and, consequently, emissions vary
within any given year for many sources,
the Board has included
this phrase
in order to exclude peak emissions that may occur due
to a process upset
or other abnormal operating conditions or due
to an effort by a source to increase its emissions
in order to
qualify for a looser Rule 204(e)(2) emission limitation.
We note
that the phrase “normal cyclical variations” also appears
in the
Rule 101 definition of
“modification”.
The theory behind Rule 204(e)(3),
the mechanism for
obtaining
a site—specific emission limitation as an alternate to
the Rule 204(e)(1)
or
(e)(2)
limitations, has been discussed
in
detail previously.
Although this Rule maintains the basic
concept proposed by the Agency,
it has been revised
in several
32—589
—18—
respects.
Tinder
the Agency’s proposals,
sources would have
applied to the Agency for an alternate standard by means
of
a
permit application.
Citizens groups objected to this procedure
because no hearing was required and,
therefore,
the opportunity
for citizen output prior to the grant
of an alternate standard
was not insured
(P.1645—1655).
Furthermore,
U.S.
EPA indicated
that all site—specific emission limitations must be submitted as
revisions to the Illinois SIP (P.2256).
We have changed the
Agency’s proposal to provide for
a hearing before the Board in
order to allow
for citizen participation and
to satisfy the
requirement of Section 110(a)(3)
of the Clean Air Act that any
revisions to a SIP be adopted only after public hearing.
Rule 204(e)(3)
is largely self—explanatory.
The burden of
proof
is on the petitioning source to prove that under any
potential meteorological conditions
or any foreseeable operating
conditions the source will not cause or contribute to a violation
of air quality standards or violate
any
applicable
PSI)
increment.
Only meteorological conditions which can occur in the area in
which the source is
located need be considered.
All forseeable
operating conditions,
including maximum and less than maximum
firing rate, must he considered because a source’s maximum impact
on ground level concentrations may occur under operating
conditions other than maximum firing
rate.
Procedures applicable
to sources petitioning for an alternate standard pursuant to Rule
204(e)(3) were proposed by the Board on January
18, 1979,
in
P78-6, In the Matter of Procedural Rules Revisions.
The proposed
procedural
rules are based primarily on Exhibit
64 in P75—5,
which was the proposed Agency guidelines
for sources applying for
an alternate standard.
We note that the Rule requires sources granted an alternate
standard to conduct an ambient monitoring and dispersion modeling
program for one year.
At the end of this program, the results
are to be submitted to the Agency in a new operating permit
application.
If the results indicate that the source could
prevent the attainment or maintenance of an air quality standard,
then the Agency is mandated to deny the permit based upon a
potential violation of Rule 102.
Rule 204(f): Sulfur Standards for Process Emission Sources
In accordance with the Agency’s proposal, Rule 204
(f)(1)(D)
has been amended to delete the requirement that existing
processes designed to remove sulfur compounds from the flue gases
of petroleum and petro—chemical processes meet the SO2 emission
limitation determined by Rule 204(e). Testimony indicated that
Rule 204(e)
is not an appropriate rule to apply to these sources
(P. 12).
Rule 204(g):
Measurement Methods
Rule 204(g)(3) describes a method of averaging which is to
be used
in order to determine compliance with subparagraphs
(a),
(b),
(c), and
(d) of Rule 204.
The Agency had proposed that the
coverage of Rule 204(g)(3)
be extended to subparagraph
(e)
of
32—590
—19—
Rule 204.
Illinois Power Co. suggested that Rule 204(g)(3)
be
modified
(P.2193—2199).
The U.S. Environmental Protection Agency
also indicated that Rule 204(g)(3) should be changed in order to
prevent disapproval
of the SIP revisions for nonattainment areas
(P.2259).
The Board makes no change to 204(g)(3).
The record in
this matter, voluminous though
it is,
does not contain sufficient
support for any change.
Rule 204(h):
Compliance Dates
Rule 204(h)
specifies compliance dates applicable to all
paragraphs in Rule 204.
The Rule
is largely a reorganiation of
the previous Rule 204(h).
The only paragraphs
of Rule 204 for
which substantive changes
in compliance dates are intended are
the paragraphs modified by P75-5 specifically:
Rules
204(c)(1)(B), 204(c)(1)(C), 204(e)(l),
204(e)(2)
and Rule
204(e)(3).
The modified compliance dates
for these specified
rules are self—explanatory.
The Agency’s proposal had allowed
sources which had complied with the previous Rule 204(e)
formula
three years from the effective date of the regulation to comply
with the new Rule 204(e)(l)
formula.
However, because Rule
204(e)(2) has “grandfathered in” such sources,
the need for the
three year delay has been eliminated.
We note that,
although the
compliance date under Rule 204(e)(3)
is,
for sources not in
compliance with the previous Rule 204(e),
the date of approval of
the alternate standard,
such sources are subject to enforcement
actions for violation of Rule 204(e)(1)
if not in compliance with
that rule
as of December 14,
1978.
Rule 204(i):
Dispersion Enhancement Techniques
Rule 204(i)
states that the following dispersion enhancement
techniques shall not be used as a means of complying with the
Rule 204(e) mass emissions limitations.
The Rule generally
parallels the Agency’s proposal.
Certain clarifying changes have
been made,
however.
First of
all, we have specifically defined
intermittent control systems
as
a dispersion enhancement
technique,
in accordance with Section 123
of the Clean Air Act
Amendments of
1977.
Secondly, the Agency’s proposal was subject
to the interpretation that any stack height increase was
a
dispersion enhancement technique and,
thus, prohibited as
a
method of complying with Rule 204(e).
Several industry
representatives expressed concern over the wording of
the
Agency’s proposal, particularly
in light of the Clean Air Act
Amendments which allow stack heights up to good engineering
practice to be included
in determining emission limitations
(P.2125,
2242).
Recognizing that an increase in stack height may
be environmentally
sound,
we have specified that increases in
stack height “in excess of good engineering practice necessary to
prevent downwash or fumigation conditions” are dispersion
enhancement techniques.
However,
the Rule also contains the
proviso “except as provided by Section 123 of the Clean Air Act
and Regulations promulgated thereunder,” which
is intended to
32—591
—20—
provide that any inconsistencies between this Rule and Section
123 of the Clean Air Act be resolved in favor of the Clean Air
Act.
The Rule also defines an increase
in exit gas temperature
as
a dispersion enhancement technique.
However, because certain
types of air pollution control equipment,
such as wet scrubbers,
may decrease the exit gas temperature, which
in turn results
in a
reduction in plume rise,
sources will be allowed to reheat the
flue gas to the pre—scrubbing temperature.
Mr. Dumelle Concurs.
I, Christan
L. Moffett,
Clerk of the Illinois Pollution
Contrq.~)3oard,herep~certify the above Opinion was adopted on
the /~‘)
day of
~
,
1979 by a vote
Christan L. Moffet?
rk
Illinois Pollution
ontrol Board
32—592
