
[Federal Register: October 15, 2008 (Volume 73, Number 200)]
[Rules and Regulations]               
[Page 60957-60963]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr15oc08-19]                         

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R04-OAR-2005-AL-0002-200819; FRL-8727-7]

 
Approval and Promulgation of Implementation Plans: Alabama: 
Approval of Revisions to the Visible Emissions Rule

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: EPA is taking final action to approve revisions to the Visible 
Emissions portion of the State Implementation Plan (SIP) submitted to 
EPA by the State of Alabama, via the Alabama Department of 
Environmental Management (ADEM), on September 11, 2003 (the ``2003 ADEM 
submittal''), and amended by a revision submitted to EPA on August 22, 
2008 (the ``2008 ADEM amendment''). The open burning portion of the 
State of Alabama's 2003 ADEM submittal was previously approved in a 
separate action on March 9, 2006 (71 FR 12138) and is not relevant to 
this action. These revisions amend the requirements for units that are 
required to operate continuous opacity monitoring systems (COMS) and 
that are not subject to any opacity limits other than those of the 
Alabama SIP.

DATES: Effective Date: This rule will be effective November 14, 2008.

ADDRESSES: EPA has established a docket for this action under Docket 
Identification No. EPA-R04-OAR-2005-AL-0002. All documents in the 
docket are listed on the www.regulations.gov Web site. Although listed 
in the index, some information is not publicly available, i.e., 
Confidential Business Information or other information whose disclosure 
is restricted by statute. Certain other material, such as copyrighted 
material, is not placed on the Internet and will be publicly available 
only in hard copy form. Publicly available docket materials are 
available either electronically through www.regulations.gov or in hard 
copy at the Regulatory Development Section, Air Planning Branch, Air, 
Pesticides and Toxics Management Division, U.S. Environmental 
Protection Agency, Region 4, 61 Forsyth Street, SW., Atlanta, Georgia 
30303-8960. EPA requests that, if at all possible, you contact the 
person listed in the FOR FURTHER INFORMATION CONTACT section to 
schedule your inspection. The Regional Office's official hours of 
business are Monday through Friday, 8:30 to 4:30, excluding Federal 
holidays.

FOR FURTHER INFORMATION CONTACT: Mr. Joel Huey, Regulatory Development 
Section, Air Planning Branch, Air, Pesticides and Toxics Management 
Division, Region 4, U.S. Environmental Protection Agency, 61 Forsyth 
Street, SW., Atlanta, Georgia 30303-8960. The telephone number is (404) 
562-9104. Mr. Huey can also be reached via electronic mail at 
huey.joel@epa.gov. For information regarding the Alabama SIP, contact 
Ms. Stacy Harder at the same address listed above. The telephone number 
is (404) 562-9042. Ms. Harder can also be reached via electronic mail 
at harder.stacy@epa.gov.

SUPPLEMENTARY INFORMATION: 

Table of Contents

I. What Is the Background for This Action?
II. What Action Is EPA Taking?
III. Response to Comments
IV. Final Action
V. Statutory and Executive Order Reviews

I. What Is the Background for This Action?

    On September 11, 2003, ADEM submitted a request for EPA approval of 
a SIP submittal containing proposed revisions to the Visible Emissions 
portion of the Alabama SIP, found at ADEM Administrative Code (AAC) 
Chapter 335-3-4-.01, ``Visible Emissions,'' and pertaining to sources 
of particulate matter (PM) emissions. In an action published on April 
12, 2007 (72 FR 18428), EPA proposed to approve the proposed revisions 
contingent upon Alabama submitting a revised SIP submittal addressing 
EPA's concerns regarding impacts of the rule changes on attainment of 
the National Ambient Air Quality Standards (NAAQS), as set forth in 72 
FR 18428-18434. EPA's proposal notice stated that the State would have 
to provide EPA with a revised SIP submittal consistent with certain 
changes described by EPA in our April 12, 2007, notice of proposed

[[Page 60958]]

rulemaking, before EPA would approve the revisions.
    EPA provided the public with 60 days to submit comments on our 
proposed rule and the specific changes needed to make the Alabama 
submittal approvable into the Alabama SIP. At the request of a 
commenter, EPA extended the public comment period by 30 days to July 
11, 2007. We received four comment letters from industry 
representatives and one from the State air pollution control agency, 
all of which were in favor of the rulemaking. We received one comment 
letter, submitted on behalf of four environmental groups, opposed to 
it. In general, comments received that were adverse to the proposed 
rulemaking expressed concerns related to air quality impacts, 
particularly on the particulate matter NAAQS, suggested inadequate 
modeling analyses by EPA, and expressed concern with EPA's technical 
assessment of the relationship between opacity and particulate matter 
mass emissions. These comments, and EPA's responses to them, are 
discussed in more detail below in Part III, ``Response to Comments.''
    Following the close of the comment period, EPA and ADEM discussed 
some of the issues raised by the commenters, including comments 
regarding the potential impact of a revised Visible Emissions rule on 
attainment of the PM2.5 NAAQS in Alabama. Documents 
memorializing these conversations are part of the docket for this 
action. As a result of these discussions, ADEM decided to submit the 
necessary revisions proposed by EPA in our April 2007 Federal Register 
notice to support final approval. ADEM also decided to include an 
additional limitation on opacity based on public comments. This 
additional provision limits subject sources to a daily opacity average 
of no more than 22 percent, excluding periods of startup, shutdown, 
load change and rate change (or other short intermittent periods upon 
terms approved by ADEM's Director and included in a State-issued 
permit).\1\ This 22 percent cap was selected because it is equivalent 
to the maximum daily opacity average allowable under the current 
approved SIP, which allows opacity of up to 40 percent for 24 six-
minute averages per day and up to 20 percent for the remainder of the 
day, excluding periods of startup, shutdown, load change and rate 
change (or other short intermittent periods upon terms approved by 
ADEM's Director and included in a State-issued permit). That is, under 
both the existing SIP and the August 22, 2008, revisions, if a source 
were to operate at its maximum allowable opacity for an entire calendar 
day, excluding periods of startup, shutdown, load change and rate 
change (or other short intermittent periods upon terms approved by 
ADEM's Director and included in a State-issued permit), the opacity 
average for that day would be 22 percent. The equation below 
illustrates the calculation of 22 percent average daily opacity allowed 
under the current SIP when T1, the number of six-minute 
average periods of startup, shutdown, load change and rate change (or 
other short intermittent periods upon terms approved by ADEM's Director 
and included in a State-issued permit), is zero.\2\
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    \1\ The director's discretion provisions under Alabama rule 335-
3-4-.01(1)(c) and (d) would be unchanged by this SIP revision, so 
periods of excess emissions allowed in a permit pursuant to those 
provisions would continue to be allowed, as noted here. EPA notes 
that, as the director's discretion provisions are not being revised 
by ADEM or reviewed by EPA at present, nothing in this notice should 
be considered as approving those provisions.
    \2\ This equation includes the variable, T1, to 
represent periods of startup, shutdown, load change and rate change 
(or other short intermittent periods upon terms approved by ADEM's 
Director and included in a State-issued permit) because such periods 
are allowed under both the existing SIP and the proposed revision, 
although EPA expects that such periods will not occur during most 
days. In calculating average opacity over a quarter in the April 12, 
2007, proposal, EPA also used a range of values for such periods.
[GRAPHIC] [TIFF OMITTED] TR15OC08.007

We derived allowable average daily opacity equations for the current 
SIP-approved rule and the 2008 ADEM submittal, substituted various 
exemption durations (T1) in the equations, determined the 
corresponding allowable average daily opacities, and organized the 
results as shown in Table 1 below.

 Table 1--Calculated Allowable Average Daily Opacity Levels for Various Startup, Shutdown, Load Change, and Rate Change Durations (T1), Using Alabama's
                                                  Current SIP-Approved Rule and the 2008 ADEM Submittal
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                                             Calculated allowable average daily opacity (percent) for various startup, shutdown, load change, and rate
                                                                                       change durations (T1)
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                                              T1 = 0          T1 = 12         T1 = 24         T1 = 48        T1 = 120        T1 = 216        T1 = 240
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Current SIP Approved Rule...............            22.0            26.0            30.0            38.0            62.0            94.0           100.0
2008 ADEM Submittal.....................            22.0            25.9            29.8            37.6            61.0            92.2           100.0
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    The text of the new paragraphs added to AAC Chapter 335-3-4-.01 now 
reads as follows:

    (3) The conditions in paragraphs (4) and (5) of this rule apply 
to each emissions unit that meets all of the following requirements:
    (a) A Continuous Opacity Monitoring System (COMS) is used for 
indication of opacity of emissions;
    (b) With respect to opacity limitations, the units are subject 
only to the opacity provisions stated in paragraph (1) of this rule; 
and
    (c) The COMS system utilized is required to comply with the 
requirements of 40 CFR

[[Page 60959]]

60.13 or 40 CFR 75.14 (if applicable) and is required to be 
certified in accordance with the requirements of 40 CFR part 60, 
Appendix B, Performance Specification 1.
    (4) Except as otherwise exempt under subparagraphs (1)(c) or 
(1)(d) of this rule, no permittee shall discharge into the 
atmosphere from any source of emission, particulate of an opacity 
greater than that designated as twenty percent (20%) opacity, as 
determined by a six (6) minute average, except that during each 
calendar quarter, the permittee may discharge into the atmosphere 
from any emissions unit qualifying under paragraph (3) of this rule, 
particulate with an opacity exceeding 20% for not more than twenty-
four (24), six (6) minute periods in any calendar day, if such 
periods do not exceed 2.0 percent of the source calendar quarter 
operating hours for which the opacity standard is applicable and for 
which the COMS is indicating valid data.
    (5) No permittee shall discharge into the atmosphere from any 
source of emission particulate of an opacity greater than 22% 
(excluding exempt periods allowed under subparagraphs (1)(c) and 
(1)(d) of this rule) averaged over each calendar day.
    (6) For a person subject to paragraph (4) of this rule, 
compliance with the opacity standards in this rule shall be 
determined by COMS data.
    (7) For emissions units described in paragraph (3) above, the 
permittee shall comply with paragraphs (4) and (5) within 6 months 
of EPA approval of paragraphs (3), (4), (5), and (6). Until 6 months 
after EPA approval of paragraphs (3), (4), (5), and (6), emissions 
units described by paragraph (3) above shall be subject to the 
emission limit in subparagraph (1)(a) of this rule, the exceptions 
in subparagraphs (1)(b), (1)(c) and (1)(d) of this rule, and the 
compliance measurement techniques in paragraph (2) of this rule.

    For overall completeness of the changes to the Visible Emissions 
rule, ADEM also made minor revisions to AAC rules 335-3-4-.01(1)(a), 
335-3-4-.01(1)(b), and 335-3-4-.01(2).\3\ In accordance with the 
requirements of the Clean Air Act (CAA), as identified by EPA in our 
April 2007 proposed rule, ADEM held a public hearing on these revisions 
on August 6, 2008. The state-adopted revisions were submitted to EPA on 
August 22, 2008.
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    \3\ The additional revisions are as follows in the underlined 
text:
    AAC 335-3-4-.01(1)(a): `` Except as provided in subparagraphs 
(b), (c), (d), or (e) of this paragraph, and paragraph (3) of this 
rule, no person shall discharge into the atmosphere from any source 
of emission, particulate of an opacity greater than that designated 
as twenty percent (20%) opacity, as determined by a six (6) minute 
average.''
    335-3-4-.01(1)(b): ``For a person not covered by paragraphs (3), 
(4), and (5) of this rule, [d]uring one six (6) minute period in any 
sixty (60) minute period, a person may discharge into the atmosphere 
from any source of emission, particulate of an opacity not greater 
than that designated as forty percent (40%) opacity.''
    335-3-4-.01(2): ``For a person subject to subparagraph (1)(b) of 
this rule, [c]ompliance with opacity standards in this rule shall be 
determined by conducting observations in accordance with Reference 
Method 9 in Appendix A, 40 CFR Part 60, as the same may be amended 
requiring a six (6) minute average as determined by twenty-four (24) 
consecutive readings, at intervals of fifteen (15) seconds each.''
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II. What Action Is EPA Taking?

    Today's action addresses revisions to Alabama SIP rule 335-3-4-.01 
(``Visible Emissions''), submitted initially in 2003 and significantly 
revised and re-submitted on August 22, 2008. These revisions amend the 
requirements for units that operate COMS and that are not subject to 
any opacity limits other than those of the Alabama SIP.\4\ After 
consideration of the comments received in response to EPA's April 12, 
2007, proposed rule and the State's final SIP revision submittal of 
August 22, 2008, EPA is taking final action to approve the revisions to 
the Visible Emissions portion of the Alabama SIP rule. EPA is taking 
this action pursuant to section 110(k) of the CAA.
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    \4\ Although this new opacity standard would only apply to 
certain sources using COMS, consistent with EPA's and ADEM's 
credible evidence rules, nothing in the rule as revised should be 
construed to preclude the use of COMS to enforce the existing 
standard or the use of EPA Method 9 to enforce the revised standard.
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    This final action is based on EPA's determination that the proposed 
SIP revision satisfies the requirements of section 110(l) of the CAA. 
Consistent with our discussion of these issues in the proposed 
rulemaking (see 72 FR 18428), and after consideration of all public 
comments submitted thereon, this determination is based upon our 
findings that (1) the revision would not increase the allowable average 
opacity levels; and (2) the relationship between changes in opacity and 
increases or decreases in ambient PM2.5 levels cannot be quantified 
readily for the sources subject to this SIP revision, and is 
particularly uncertain for short-term analyses. In the proposal we 
calculated the ``average quarterly opacity'' allowed under both the 
existing SIP and the proposed revision and showed that the proposed 
revision, with changes specified in the notice, would result in no 
greater average quarterly opacity allowed than what is allowed under 
the current standard. Accordingly, we relied primarily on the first 
finding for a conclusion that the proposed revision, with changes, 
satisfied the requirements of section 110(l) with respect to the annual 
PM NAAQS. We relied on the second finding for a conclusion that the 
proposed revision satisfied the requirements of section 110(l) with 
respect to the 24-hour PM NAAQS.
    In evaluating the changes submitted by Alabama on August 22, 2008, 
EPA notes that the revised rule as submitted is consistent with, but 
not limited to, the revisions outlined by EPA in the proposal notice. 
EPA's April 12, 2007, notice proposed to approve a revised rule, if one 
were submitted, allowing up to 2.4 hours per day of operation at 
opacity levels in excess of 20 percent, provided that the total of such 
periods did not exceed 2 percent of operating time in a quarter, 
excluding periods of startup, shutdown, load change and rate change (or 
other short intermittent periods upon terms approved by ADEM's Director 
and included in a State-issued permit). The changes identified by EPA 
were intended to ensure that the allowable average quarterly opacity 
under the revised rule would be at least as stringent as (i.e., equal 
to or lower than) that allowed by the current approved SIP, and to 
clarify that only a single version of the opacity standard applies to 
any unit.
    As discussed above, the rule as submitted includes not only the 
limits identified by EPA in the proposal notice but also an additional 
restriction that a source's daily average opacity may not exceed 22 
percent, excluding periods of startup, shutdown, load change and rate 
change (or other short intermittent periods upon terms approved by 
ADEM's Director and included in a State-issued permit). As a result, 
unlike the opacity limits evaluated in the proposal, the average daily 
opacity allowed under the proposed revision as submitted is now no 
greater than under the current SIP. In this way, the rule as submitted 
allows us to evaluate the possible impact of changes to the opacity 
standard on the daily PM NAAQS using the approach we identified in the 
proposal for evaluating the possible impact of changes on the annual PM 
NAAQS. Since a calendar day is the shortest period over which 
compliance with the PM NAAQS is measured, EPA believes it is 
appropriate under this approach to evaluate whether the allowed average 
opacity over a calendar day would be any greater under the proposed 
revision, as submitted, as compared to the existing SIP. Accordingly, 
EPA believes both of the findings cited in the April 12, 2007, proposal 
provide support for our conclusion that the proposed revision as 
submitted satisfies the requirements of section 110(l) with respect to 
the 24-hour PM NAAQS.
    The Alabama Visible Emissions rule revision being approved today 
provides, for sources meeting the criteria of the revised rule, two 
situations where opacity levels above 20 percent are

[[Page 60960]]

allowed: (1) 24 six-minute averages per day of up to 100 percent 
opacity, provided that no subject source can exceed a daily average 
opacity of 22 percent, excluding periods of startup, shutdown, load 
change and rate change (or other short intermittent periods upon terms 
approved by ADEM's Director and included in a State-issued permit); and 
(2) periods of startup, shutdown, load change and rate change (or other 
short intermittent periods upon terms approved by ADEM's Director and 
included in a State-issued permit). The provisions in the first 
instance above do not apply if a source exceeds 20 percent opacity for 
more than two percent of the remaining operating time in a quarter, 
after subtracting out periods of startup, shutdown, load change and 
rate change (or other short intermittent periods upon terms approved by 
ADEM's Director and included in a State-issued permit).

III. Response to Comments

    EPA proposed to approve the Visible Emissions portion of the SIP 
revision contained in the 2003 ADEM submittal, provided the State 
revised it as described in the April 12, 2007, Federal Register Notice 
and submitted it as a SIP revision. At the request of a commenter, EPA 
extended the 60-day public comment period to 90 days, ending July 11, 
2007. 72 FR 32569 (June 13, 2007). The final rule reflects our 
consideration of the State's revision submitted on August 22, 2008, and 
all comments received on the proposed action. This section responds to 
the significant comments.
    Comment 1: Commenters objected to EPA's approval of Paragraphs (3), 
(4) and (5) of AAC rule 335-3-4-.01, stating that doing so would be 
approving an ``automatic exemption'' from certain emission limitations 
that must function on a ``continuous basis'' and would result in a 
violation of Section 302(k) of the CAA and 40 CFR 51.100(z).
    Response: The revisions to ACC rule 335-3-4-.01 amend the 
requirements for certain units that operate COMS and are, therefore, 
revisions to the rule itself. A source that meets the requirements of 
the revised standard will be in continuous compliance with the 
standard. The provisions of the CAA and its implementing regulations 
cited by the commenters do not require that all SIP measures require 
compliance with the same numerical emission limitation at all times. 
See Kamp v. Hernandez, 752 F.2d 1444 (9 Cir.), modified, 778 F.2d 527 
(9th Cir. 1985). EPA believes the rule, as amended, does not violate 
Section 302(k) of the CAA and 40 CFR 51.100(z).
    Comment 2: Commenters stated that EPA's analysis of ACC rule 335-3-
4-.01 is ``illegal'' because an ``analysis premised on the notion that 
a relaxation is acceptable as long as average emissions are equal to or 
no lower than the status quo runs afoul of Hall, which explicitly 
rejected that type of analysis.''
    Response: The 9th Circuit Court of Appeals decision in Hall v. U.S. 
E.P.A., 273 F.3d 1146, does not require EPA to disapprove the SIP 
revision at issue. It is not binding precedent in the 11th Circuit 
Court of Appeals, and two other circuits have agreed with EPA's view 
that a SIP revision may be approved under section 110(l) ``unless the 
agency finds it will make air quality worse.'' See Kentucky Resources 
Council, Inc. v. EPA, 467 F.3d 986 (6th Cir. 2006); GHASP v. EPA, No. 
06-61030 (5th Cir. Aug. 13, 2008). Furthermore, although the Hall court 
adopted an approach, based on the facts of that case, under which ``EPA 
must be able to conclude that the particular plan revision before it is 
consistent with the development of an overall plan capable of meeting 
the Act's attainment requirements,'' EPA believes this revision is 
consistent with development of an overall plan capable of demonstrating 
attainment in a timely fashion.
    Comment 3: Commenters stated that EPA must perform modeling 
analysis at every facility subject to the Alabama Visible Emissions 
rule at AAC rule 335-3-4-.01 and suggest that the State and EPA will be 
abdicating their responsibility to protect the NAAQS if they do not 
perform modeling analysis for every facility subject to the proposed 
rule.
    Response: EPA disagrees with the commenters that modeling is 
required at every facility. As a matter of law, the CAA does not 
require EPA to perform modeling analysis at every facility subject to 
the Alabama Visible Emissions rule. For purposes of analyzing SIP 
revisions, as long as EPA evaluates all of the information before it in 
light of its expertise and has a reasonable basis for concluding that 
the rule revision satisfies the requirements of section 110(l) of the 
CAA, we are authorized to act on a SIP revision. As set forth in the 
proposed rule, we believe our technical analysis supports approval of 
the proposed revisions to the Visible Emissions portion of the Alabama 
SIP, rule 335-3-4-.01. See 72 FR 18428, 18431 (April 12, 2007).
    Comment 4: Commenters stated that CAA section 110(l) requires EPA 
to evaluate whether the proposed SIP revision will make the ambient air 
worse and whether the existing SIP and the proposed revisions, taken 
together, will still achieve the necessary pollution reductions 
required for the State to continue to meet the NAAQS.
    Response: Under section 110(l) of the CAA, EPA may not approve 
revisions to SIPs if the revisions would interfere with any applicable 
requirement concerning attainment and reasonable further progress, or 
any other applicable requirement of the CAA. Therefore, in determining 
whether to approve the revisions to Alabama's Visible Emissions rule, 
we considered the relevant impacts of the proposed change in light of 
the type of requirement affected by the requested revision. In this 
instance, the State is proposing revisions to its opacity requirements. 
EPA notes that the opacity standard itself is not a NAAQS and that the 
PM emission reduction standards remain unchanged in the approved 
Alabama SIP. We have considered the impact of Alabama's proposed 
revision on the NAAQS for PM10 and PM2.5, and on 
other applicable requirements, and determined that it satisfies the 
requirements of CAA section 110(l).
    Comment 5: Commenters opposed EPA's approval of paragraphs (3), (4) 
and (5) of AAC rule 135-3-4-.01, stating that EPA's analysis did not 
include whether the current rule ``as is'' is adequately protective of 
the NAAQS and, therefore, EPA's comparison analysis is incapable of 
providing the information necessary to evaluate the 2003 ADEM 
submittal.
    Response: The CAA requires EPA to evaluate the initial SIP 
submittal as well as all proposed revisions pursuant to the conditions 
set forth in section 110(l) of the CAA as cited above. EPA interprets 
the requirements of section 110(l) to apply with respect to the 
specific changes being proposed. EPA does not interpret section 110(l) 
to require a full attainment or maintenance demonstration before any 
changes to a SIP may be approved. See Kentucky Resources Council, Inc. 
v. EPA, 467 F.3d 986 (6th Cir. 2006); see also e.g., 70 FR 53 (Jan. 3, 
2005), 70 FR 28429 (May 18, 2005) (proposed and final rules, upheld in 
Kentucky Resources, which discuss EPA's interpretation of section 
110(l)). In this action, the State proposed only revisions to its 
opacity requirements. We evaluated the proposed revisions in light of 
the relationship between opacity and PM emissions and determined that a 
reliable and direct correlation could not be readily established, 
particularly for short-term periods. Nonetheless, there is at least an 
indirect relationship between opacity and PM emissions, including the 
use of opacity to track the

[[Page 60961]]

effectiveness of PM control equipment operation, and we considered the 
impact of Alabama's 2003 and 2008 revisions on the NAAQS for 
PM10 and PM2.5 and on other applicable emission 
limits. We concluded that these SIP revisions satisfy the requirements 
of CAA section 110(l).
    Comment 6: Commenters stated that EPA's rationale for approving AAC 
rule 335-3-4-.01, ``Visible Emissions,'' is not correct because AAC 
rule 335-3-14-.03(1)(h)(2), ``Emergency Exception,'' serves essentially 
the same purpose as a ``malfunction exception.'' Therefore, ADEM's 
claim that there is pressing need to adopt a new two-percent exemption 
lacks merit.
    Response: We did not consider AAC rule 335-3-14-.03(1)(h)(2), 
``Emergency Exception,'' in our decision to approve revisions to ACC 
rule 335-3-4-.01, ``Visible Emissions.'' EPA notes that it does not 
interpret AAC rule 335-3-14-.03(1)(h)(2) as providing the same sort of 
exemption for equipment malfunctions that is included in other SIPs 
(and would be approvable, subject to certain limitations, under current 
EPA policy and guidance). Section 110(l) requires us to evaluate 
proposed SIP revisions in relation to applicable requirements of the 
CAA, not state rules. EPA is not basing our approval of the revision on 
the lack of a ``malfunction exemption'' in Alabama's SIP.
    Comment 7: Commenters stated that EPA may not have complied with 
the Agency's SIP Consistency Policy. If not, then the Regional 
Administrator was not authorized as a matter of law to promulgate the 
proposed SIP revision.
    Response: EPA complied with its SIP consistency policy. 
Documentation of the process is contained in the docket for this rule.
    Comment 8: Commenters stated that modeling shows the revisions to 
AAC rule 335-3-4-.01 would interfere with the PM2.5 NAAQS.
    Response: EPA does not agree that the modeling submitted by the 
commenters shows the revisions to the Alabama Visible Emissions rule 
would interfere with the PM2.5 NAAQS. First, the modeling 
submitted by the commenters assumed that maximum PM emissions will 
occur at 100 percent opacity and that 100 percent opacity will occur 
when the electrostatic precipitator (ESP) is turned off. Commenters did 
not submit data to support this assumption. Data reviewed by EPA in 
considering this SIP revision suggest a wide variation in opacity 
associated with PM emission rates across a range of operating 
conditions for ESPs. For example, data from Review of Concurrent Mass 
Emission and Opacity Measurements for Coal-burning Utility and 
Industrial Boilers (EPA-600/7-80-062), which is listed in the docket 
for this rule and is publicly available, on similarly equipped and 
operated coal-fired electric utilities illustrate the variability of 
opacity with respect to ESP operation and of opacity with particulate 
matter emissions. In one example, a facility equipped with a fully 
energized ESP exhibited 22 percent opacity and a PM emissions rate of 
0.314 lbs PM per million British thermal units (BTU). During another 
test run under the same operating conditions, this facility exhibited a 
45 percent increase in opacity to 32 percent opacity, but a 60 percent 
decrease in PM emissions rate to 0.126 lbs PM per million BTU. 
Moreover, during another test series for this facility in which the ESP 
was fully energized for one run, then turned off for another run, the 
opacity remained constant at 22 percent. Thus, evidence in the docket 
indicates that, at least for some sources, there is not a universal 
correlation between operating conditions of the ESP and opacity.
    Second, one commenter also stated that the facility could operate 
at 100 percent opacity for consecutive periods of 2.4 hours per day and 
up to 4.8 hours in two days back-to-back, thus creating the potential 
for significant short-term impacts on ambient air quality. The 
commenter is correct, provided that these periods of operation do not 
cause the source to exceed two percent of the source calendar operating 
hours or an average daily opacity of 22 percent. Given Alabama's newly 
adopted rule, in a hypothetical situation in which a source operated at 
100 percent opacity for 2.4 hours, the facility would be limited to no 
more than 13.3 percent opacity for the remainder of the day; this limit 
is two-thirds of the otherwise generally applicable limit of 20 
percent. EPA notes that the 24-hour PM NAAQS are measured on a 
calendar-day basis, not as a rolling 24-hour average. Accordingly, EPA 
does not believe the possibility that a facility could operate for 4.8 
hours in two consecutive calendar days indicates that the revised rule 
would interfere with attainment and maintenance of the 24-hour PM 
NAAQS. Furthermore, as discussed below, nothing in the Visible 
Emissions rule excuses a source from compliance with any applicable PM 
emission limit.
    The AERMOD model (a regulatory dispersion model) requires several 
inputs, including PM emission rate. Some commenters assumed a 
correlation between opacity and PM emission rate as part of their 
efforts to model the impact of the revised opacity rule on PM emissions 
and ambient PM concentrations. Opacity, the degree to which emissions 
reduce the transmission of light and obscure the view of an object in 
the background,\5\ is a condition, not a pollutant. For a useful 
relationship to exist between the opacity and mass concentration of the 
particulate emissions from a pollution source, the characteristics of 
the particles (size, shape, and composition) must be sufficiently 
constant, and for a conventional transmissometer (e.g., COMS) to be 
useful as a monitor of the mass concentration, the particulate 
characteristics must remain constant over a useful period of time.\6\
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    \5\ Measurement of the Opacity and Mass Concentration of 
Particulate Emissions by Transmissometry, EPA-650/2-74-128, p3.
    \6\ Measurement of the Opacity and Mass Concentration of 
Particulate Emissions by Transmissometry, EPA-650/2-74-128, p 21.
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    There is a general relationship between opacity and PM, which 
generally develops over longer periods of time. While opacity is used 
as an indicator of compliance with PM limits in certain regulatory 
programs, establishing a relationship between PM and opacity that holds 
for all sources, fuels, control devices, and operating modes can be 
complex. Opacity may not be a reliable indicator of short-term mass 
emissions, or for use in projecting changes in short-term PM ambient 
air quality concentrations. A given opacity level can be associated 
with a range of mass emissions, the level of which depends on fuels, 
industry, boiler type, and controls. Although source-specific 
correlations between opacity and mass emissions can be established for 
some sources, none have been for the sources subject to this SIP 
revision and therefore assumptions must be made about how a change in 
the opacity rule might affect the level of PM mass emissions being 
modeled. These assumptions made about the relationship drive model 
results and, thus, are important in evaluating the result of the 
modeling exercise.
    For the modeling submittals on the Colbert Plant, commenters 
assumed maximum opacity for maximum duration from turned-off PM 
emission control devices. They developed and used differing PM emission 
rates, one set of rates being four times larger than the other set of 
rates, underscoring the uncertainty inherent with relating opacity 
values to mass emissions. They both failed to include impacts of nearby 
emission sources and of secondary PM emissions, and they both used 
cumulative PM mass sizing estimates from AP-42 in their calculation of 
PM10 and PM2.5; however, one commenter

[[Page 60962]]

used an incorrect value that overpredicts PM2.5, and 
underpredicts PM10, by 2.3 times. One commenter included 
condensable PM emissions.
    PM emissions associated with turned-off control devices are 
expected to be higher than PM emissions associated with more commonly 
occurring transient malfunctions of control devices, even though 
maximum opacity may occur from either situation. In order to examine 
the impact of Alabama's rule change on the NAAQS, we would need 
additional information on the range of emission rates associated with 
100 percent opacity and other opacity levels. Estimation of PM 
emissions for a given opacity value is difficult without measurements 
and is the major deficiency and limitation of any modeling for this 
rule change. The range of emission rates that could produce 100 percent 
opacity is not known and is not discussed or established in the 
modeling submitted during the public comment period.
    Therefore, although the modeling presented by commenters shows the 
possibility of an impact on the NAAQS under a worst-case scenario, the 
modeling does not convincingly demonstrate the impact of the rule 
change on the NAAQS because the level of PM emissions while operating 
at 100 percent opacity, and the source-specific relationship between 
opacity and PM emissions, are uncertain and are not demonstrated in the 
public record. For these reasons, the modeling cannot show that the 
rule change will interfere with the 24-hour NAAQS.
    Comment 9: Commenters disagreed with EPA's assertion that ``the 
relationship between changes in opacity and increases or decreases in 
ambient PM2.5 levels cannot be quantified readily and is 
particularly uncertain for short-term and site specific analyses.''
    Response: EPA's assertion is consistent with the findings contained 
in Review of Concurrent Mass Emission and Opacity Measurements for 
Coal-burning Utility and Industrial Boilers (EPA-600/7-80-062), which 
is listed in the docket for this rule and is publicly available. That 
report was developed from over 400 concurrent particulate matter and 
opacity measurements and found that any useful and definitive 
relationships between stack particulate mass emission rates and their 
corresponding opacity levels appear to be site specific. In addition, 
as stated in the proposal notice, the uncertainty in assumptions about 
a correlation between opacity levels and ambient PM concentrations on 
short-term periods or site specific analyses is a function of many 
factors, including differences in the mass of particles that exist at 
the point of COMS measurement in the stack, the total mass of particles 
exiting the stack, including condensable particles that form 
immediately upon exposure to the ambient atmosphere, and the mass of 
particles an ambient sampler is capable of collecting. Commenters 
submitted no information that demonstrates that opacity can be reliably 
correlated with mass emissions over short time periods for a range of 
sources (or these specific sources) without performing site-specific 
analyses, and EPA is aware of none.
    Comment 10: Commenters stated that analyzing air quality impacts on 
a quarterly basis is not appropriate because EPA already has 24-hour 
NAAQS standards for PM10 and PM2.5.
    Response: As we stated in the notice of proposed rulemaking and 
earlier in this final rule, section 110(l) prohibits EPA from approving 
any revision to a SIP that would interfere with any applicable 
requirement concerning attainment and reasonable further progress, or 
any other applicable requirement. In this instance we believe that 
because the State regulation at issue pertains to opacity, the primary 
CAA requirements of concern should be impacts on compliance with the 
NAAQS for PM10 and PM2.5, which include both 
daily and annual standards. The quarterly time frame commenters refer 
to is used in AAC rule 335-3-4-.01(4) to prohibit a source from 
operating at higher opacity levels for greater than 2 percent of the 
source operating hours per calendar quarter. In light of this specific 
provision that applies on a quarterly basis, and because analyzing for 
impacts on a quarterly basis provides a conservative basis for 
assessing impacts on an annual basis, we decided it appropriate to 
analyze air quality impacts on a quarterly basis to judge interference 
with the annual standards, and we concluded the requirements of section 
110(l) have been satisfied with respect to all of the PM NAAQS.
    Comment 11: Commenters stated that the 2003 revisions to AAC rule 
335-3-4-.01, and the conditions set forth in the April 12, 2007, notice 
of proposed rulemaking, would lead to interference with compliance with 
mass particulate matter limits. As evidence that its assertion was 
correct, the commenters stated that if Tennessee Valley Authority (TVA) 
were to turn off its control equipment for any of its units at the 
Colbert plant for 2.4 consecutive hours, TVA would violate the PM 
standard (0.12 lb/mmBtu) at that unit.
    Response: The PM limit of 0.12 lb/mmBtu under the Alabama SIP does 
not include any exempt periods and continues to apply regardless of any 
revisions to the opacity rule. EPA lacks the data necessary to 
determine quantitatively what impact, if any, the revisions to the rule 
would or could have on ambient PM emissions. As described earlier, the 
commenters' assertion of an approach that allows one to determine the 
amount of ambient PM emissions based on an increase in stack opacity is 
fraught with questionable assumptions such as de-energized control 
devices yielding 100 percent opacity and 100 percent opacity providing 
maximum PM emissions.

IV. Final Action

    EPA is taking final action to approve the Visible Emissions portion 
of the SIP revisions submitted to EPA by the State of Alabama on 
September 11, 2003, and August 22, 2008. EPA is approving the revision 
of paragraphs (1) and (2), and addition of paragraphs (3), (4), (5), 
(6), and (7) to AAC rule 335-3-4-.01, ``Visible Emissions.''

V. Statutory and Executive Order Reviews

    Under the CAA, the Administrator is required to approve a SIP 
submission that complies with the provisions of the Act and applicable 
Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in 
reviewing SIP submissions, EPA's role is to approve state choices, 
provided that they meet the criteria of the CAA. Accordingly, this 
action merely approves state law as meeting Federal requirements and 
does not impose additional requirements beyond those imposed by state 
law. For that reason, this action:
     Is not a ``significant regulatory action'' subject to 
review by the Office of Management and Budget under Executive Order 
12866 (58 FR 51735, October 4, 1993);
     Does not impose an information collection burden under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     Is certified as not having a significant economic impact 
on a substantial number of small entities under the Regulatory 
Flexibility Act (5 U.S.C. 601 et seq.);
     Does not contain any unfunded mandate or significantly or 
uniquely affect small governments, as described in the Unfunded 
Mandates Reform Act of 1995 (Pub. L. 104-4);
     Does not have Federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999);
     Is not an economically significant regulatory action based 
on health or

[[Page 60963]]

safety risks subject to Executive Order 13045 (62 FR 19885, April 23, 
1997);
     Is not a significant regulatory action subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001);
     Is not subject to requirements of Section 12(d) of the 
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 
note) because application of those requirements would be inconsistent 
with the CAA; and
     Does not provide EPA with the discretionary authority to 
address, as appropriate, disproportionate human health or environmental 
effects, using practicable and legally permissible methods, under 
Executive Order 12898 (59 FR 7629, February 16, 1994).
    In addition, this rule does not have tribal implications as 
specified by Executive Order 13175 (65 FR 67249, November 9, 2000), 
because the SIP is not approved to apply in Indian country located in 
the state, and EPA notes that it will not impose substantial direct 
costs on tribal governments or preempt tribal law.
    The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the 
Small Business Regulatory Enforcement Fairness Act of 1996, generally 
provides that before a rule may take effect, the agency promulgating 
the rule must submit a rule report, which includes a copy of the rule, 
to each House of the Congress and to the Comptroller General of the 
United States. EPA will submit a report containing this action and 
other required information to the U.S. Senate, the U.S. House of 
Representatives, and the Comptroller General of the United States prior 
to publication of the rule in the Federal Register. A major rule cannot 
take effect until 60 days after it is published in the Federal 
Register. This action is not a ``major rule'' as defined by 5 U.S.C. 
804(2).
    Under section 307(b)(1) of the CAA, petitions for judicial review 
of this action must be filed in the United States Court of Appeals for 
the appropriate circuit by December 15, 2008. Filing a petition for 
reconsideration by the Administrator of this final rule does not affect 
the finality of this action for the purposes of judicial review nor 
does it extend the time within which a petition for judicial review may 
be filed, and shall not postpone the effectiveness of such rule or 
action. This action may not be challenged later in proceedings to 
enforce its requirements. (See section 307(b)(2).)

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Carbon monoxide, 
Incorporation by reference, Intergovernmental relations, Lead, Nitrogen 
dioxide, Ozone, Particulate matter, Reporting and recordkeeping 
requirements, Sulfur oxides, Volatile organic compounds.

    Dated: October 1, 2008.
J.I. Palmer, Jr.,
Regional Administrator, Region 4.

0
40 CFR part 52 is amended as follows:

PART 52--[AMENDED]

0
1. The authority citation for part 52 continues to read as follows:

    Authority: 42 U.S.C. 7401 et seq.

Subpart B--Alabama

0
2. Section 52.50(c) is amended by revising the entry for ``Section 335-
3-4.01'' to read as follows:


Sec.  52.50  Identification of plan.

* * * * *
    (c) * * *

                                                            EPA-Approved Alabama Regulations
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                               State
          State citation               Title/subject      effective date             EPA approval date                          Explanation
--------------------------------------------------------------------------------------------------------------------------------------------------------

                                                                      * * * * * * *
                                                    Chapter 335-3-4 Control of Particulate Emissions
--------------------------------------------------------------------------------------------------------------------------------------------------------
Section 335-3-4-.01..............  Visible Emissions....       9/30/2008  10/15/2008 [Insert citation of          ......................................
                                                                           publication].

                                                                      * * * * * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------

* * * * *
 [FR Doc. E8-24031 Filed 10-14-08; 8:45 am]

BILLING CODE 6560-50-P
