[Federal Register Volume 76, Number 66 (Wednesday, April 6, 2011)]
[Rules and Regulations]
[Pages 18870-18893]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2011-8032]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R04-OAR-2005-AL-0002-201047; FRL-9290-3]


Approval and Promulgation of Implementation Plans: Alabama: Final 
Disapproval 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 amend an October 15, 2008, final 
rulemaking on two State Implementation Plan (SIP) revisions regarding 
the State of Alabama's rules for visible emissions from certain 
stationary sources. EPA has now determined upon reconsideration that 
Alabama's SIP revisions, dated September 11, 2003, and August 22, 2008, 
are not approvable pursuant to the Clean Air Act (CAA or Act) section 
110(l). Accordingly, EPA is disapproving the two SIP revisions provided 
to EPA by the State of Alabama, through the Alabama Department of 
Environmental Management (ADEM), dated September 11, 2003, and August 
22, 2008 (Submittals). No further action is required by Alabama because 
the SIP revisions were not required by the CAA. As a result of this 
action, Alabama's visible emissions rule that was in the SIP prior to 
the October 15, 2008, final action will be the current SIP-approved 
rule as of the effective date of this action. EPA urges Alabama to 
undertake rulemaking that will bring its State-effective rule into 
conformance with its SIP-approved rule.

DATES: Effective Date: This rule will be effective May 6, 2011.

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 http://www.regulations.gov index. Although 
listed in the index, some information is not publicly available, i.e., 
Confidential Business Information (CBI) 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 http://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: Ms. Lynorae Benjamin, Chief, 
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) 562-9040. Ms. Benjamin can also be reached 
via electronic mail at [email protected].

SUPPLEMENTARY INFORMATION:

Table of Contents

I. What is the background for this action?
II. What action is EPA taking and what is EPA's rationale for 
disapproving the submittals?
III. Response to Comments
IV. Final Action
V. Statutory and Executive Order Reviews

I. What is the background for this action?

    This action follows three key EPA actions regarding Alabama's 
request for approval of the two visible emissions SIP revisions. The 
first was an October 15, 2008, final rule (73 FR 60957) approving 
revisions to the Alabama SIP embodied in two submittals dated September 
11, 2003, and August 22, 2008 (Submittals). The second was an April 3, 
2009, action granting a February 25, 2009, petition for reconsideration 
on the October 15, 2008, final action which had approved the SIP 
revisions. The third was an October 2, 2009, proposed rule (74 FR 
50930) identifying two alternative options being considered by EPA as 
part of the reconsideration process (the alternative proposals were 
either to affirm the October 15, 2008, rulemaking, thereby approving 
Alabama's Submittals or to amend the October 15, 2008, rulemaking, 
thereby disapproving Alabama's Submittals). EPA has now determined that 
Alabama's Submittals are not approvable pursuant to CAA section 110(l). 
Detailed background information for this action is available in the 
proposed rulemaking published on October 2, 2009. 74 FR 50930.
    In relevant but brief part, on September 11, 2003, ADEM submitted a 
voluntary \1\ request for EPA approval of a SIP revision (2003 
Submittal) containing proposed revisions to the existing EPA-approved 
visible emissions portion of the Alabama SIP, found at Alabama 
Administrative Code (AAC) 335-3-4-.01, ``Visible Emissions,'' and 
pertaining to sources of particulate matter (PM) emissions.\2\ In

[[Page 18871]]

an action published on April 12, 2007 (72 FR 18428), EPA proposed to 
approve the 2003 Submittal contingent upon the State of 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 explained that the State would have to provide EPA with 
a revised SIP submittal consistent with certain changes described by 
EPA in the April 12, 2007, notice of proposed rulemaking before EPA 
could approve the revisions. The proposal notice also described EPA's 
rationale for requesting the additional submittal. Specifically, EPA 
noted that the 2003 Submittal was not approvable because the revision 
``would allow a source to emit at a higher allowable average opacity 
percent level (as measured by a COMS--Continuous Opacity Monitoring 
System--in six-minute increments) on a quarterly basis as well as 
allowing higher short term excursions than the current approved SIP 
allows.'' 72 FR at 18430/3. EPA further explained that ``in the absence 
of a supporting demonstration of compliance with the CAA requirements 
from the State, we believe that the 2003 SIP submittal is not 
approvable as submitted.'' Id.
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    \1\ The request was ``voluntary'' because it was not 
specifically required by the CAA or its implementing regulations, 
rather, ADEM chose to revise its rules and submit the SIP revision.
    \2\ PM particles with an aerodynamic diameter less than or equal 
to a nominal 10 micrometers are referred to as PM10; PM 
particles with an aerodynamic diameter less than or equal to a 
nominal 2.5 micrometers are referred to as PM2.5. As a 
general matter, the term ``PM'' refers to particulate matter of 
unspecified size range and includes both PM10 and 
PM2.5.
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    On August 22, 2008, Alabama, through ADEM, provided EPA with an 
amended submittal (2008 Submittal). After further evaluation, EPA 
determined that it could approve the Submittals (i.e., the 2003 
Submittal as amended by the 2008 Submittal). On October 15, 2008, EPA 
took final action to incorporate into the Alabama SIP, the revisions to 
Alabama's visible emissions rule included in the Submittals. 73 FR 
60957. EPA's rationale for its approval is discussed in that final 
action. In order to approve the Submittals in 2008, EPA relied on two 
main findings: ``(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.'' 73 
FR 60959/2. The October 15, 2008, final action was effective on 
November 14, 2008 (by its terms, the Alabama rule change became 
effective, and thus applicable to sources, on May 14, 2009).
    Following the October 2008 final action, EPA received two petitions 
for reconsideration submitted on behalf of the Alabama Environmental 
Council (AEC) and other parties (Petitioners), one on December 12, 
2008, and one on February 25, 2009. EPA considered these petitions 
under section 553(e) of the Administrative Procedures Act (APA) and the 
CAA. The first petition for reconsideration raised procedural and 
substantive concerns with EPA's October 15, 2008, final action.\3\ EPA 
denied the December 12, 2008, petition via letter on January 15, 2009. 
The second petition incorporated by reference the issues raised in the 
first petition and also identified additional substantive and 
procedural concerns not included in the first petition.\4\ EPA granted 
the Petitioners' second request for reconsideration of the October 15, 
2008, final action via letter on April 3, 2009. In that letter, EPA 
explained that it anticipated initiating a new rulemaking process to 
provide additional opportunities for public comment.
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    \3\ The Petitioners raised eight main issues: (1) EPA was 
arbitrary and capricious in failing to reopen the public comment 
period when ADEM made changes to the rule after the close of the 
public comment period; (2) EPA was arbitrary and capricious in 
deviating from rulemaking policy regarding documentation of post-
comment period meetings between EPA and ADEM and failing to meet 
with Petitioners in addition to ADEM; (3) EPA was arbitrary and 
capricious in proposing to approve a SIP revision before the rule 
had even been developed at the State level; (4) EPA failed to comply 
with rulemaking procedures by failing to complete the docket prior 
to finalizing the rulemaking package; (5) the rule should not have 
been approved because it does not represent reasonably available 
control technology requirements for SIPs because Alabama has 
nonattainment areas for PM2.5; (6) EPA's approval of the 
rule is not consistent with either Section 110(l) or 193 of the CAA 
due to likely increases in short-term particulate matter emissions; 
(7) EPA's final action is not consistent with EPA policies on excess 
emissions and director's discretion; and (8) the final rule does not 
comply with 40 CFR Part 51 because it is not an ``appropriate'' 
visible emission limitation.
    \4\ The Petitioners specifically highlighted two new issues: (1) 
The DC Circuit's decision in Sierra Club v. EPA, 551 F.3d 1019 (D.C. 
Cir. 2008) (SSM MACT decision) made the Agency's action on the SIP 
revision untenable; and (2) new documents added to the docket show 
that throughout the consideration of this matter, EPA acted in an 
arbitrary and duplicitous manner in failing to re-notice the 
rulemaking for public comment given the differences between what EPA 
required of Alabama in the April 12, 2007, proposal and what Alabama 
actually submitted for approval in its August 22, 2008, submittal.
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    On December 12, 2008, Petitioners filed a lawsuit in the Eleventh 
Circuit Court of Appeals challenging EPA's October 15, 2008, final 
action. EPA and the appellants subsequently jointly stayed the 
litigation pending the conclusion of EPA's reconsideration process. 
EPA's October 2, 2009, proposed rule was EPA's initiation of a new 
rulemaking process to reconsider its prior action on the Submittals. In 
that proposal, EPA articulated two alternative options and sought 
public comment on both. One option was to affirm the October 15, 2008, 
final action (thus approving the Submittals) and the other was to amend 
the October 15, 2008, final action (thus disapproving the Submittals). 
The bases for each alternative were described in detail in the October 
2, 2009, proposed rulemaking. 74 FR at 50932-50934. The responses to 
the comments EPA received on the October 2, 2009, proposed action are 
summarized in section III of this rulemaking.

II. What action is EPA taking and what is EPA's rationale for 
disapproving the submittals?

    EPA is now taking final action to amend its October 15, 2008, final 
action and to disapprove Alabama's 2003 and 2008 SIP Submittals 
regarding its visible emissions rule. As EPA explained in its October 
2, 2009, proposed rulemaking, the primary issue for resolution is 
whether approval of the Submittals is consistent with the requirements 
of the CAA, specifically, the requirements of section 110(l). If the 
approval were appropriate under section 110(l), EPA would need to 
consider whether it would also meet the requirements of section 193, 
given that the visible emissions rules in question were in effect prior 
to November 15, 1990, and apply to some sources that are located in 
areas designated nonattainment for one or more NAAQS. In light of the 
fact that this SIP revision would apply statewide, including 
nonattainment areas, EPA has concluded that it cannot approve the SIP 
revision under section 110(l) if it would worsen air quality by 
allowing increased emissions of criteria pollutants or precursors to 
such criteria pollutants. In particular, if the revision would result 
in increases in emissions of pollutants for which an area is designated 
nonattainment, specifically PM2.5, EPA considers that 
allowing increased emissions of such pollutants would interfere with 
the area's ability to attain the NAAQS.\5\ See, e.g., 70 FR 53

[[Page 18872]]

(January 3, 2005); 70 FR 28429 (May 18, 2005) (previous rulemaking 
actions addressing section 110(l)).
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    \5\ With respect to attainment areas, section 110(l) requires 
that an approvable SIP revision not interfere with maintenance of 
the NAAQS or any other requirement of the CAA. In some 
circumstances, allowing increases in criteria pollutants may not 
interfere with maintenance of the NAAQS. EPA has not analyzed 
whether this SIP revision would be approvable with respect to 
attainment areas only because the Submittals included rules that 
applied throughout Alabama, which includes both attainment and 
nonattainment areas, and the State did not make a showing that 
emissions from such sources would not interfere with maintenance of 
the NAAQS in attainment areas and with attainment of the NAAQS in 
nearby nonattainment areas. Similarly, EPA is not basing this 
decision on section 193 because the Submittals are not approvable 
under section 110(l); however, section 193 would have to be 
addressed before EPA could consider approval of the revisions.
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    In this particular circumstance, the analysis of whether the 
Submittals satisfy the CAA is made more difficult by the uncertainty in 
the precise relationship between the opacity of a stack emission stream 
and the mass of PM in the same emission stream at the affected sources. 
After consideration of all the issues raised by the Petitioners in 
their February 2009 petition for reconsideration, as well as comments 
received on the October 2, 2009, proposed rulemaking from many industry 
groups, individual companies, state agencies, and other non-
governmental organizations, EPA has concluded that disapproving the 
2003 and 2008 Submittals results in the interpretation of the CAA that 
is most consistent with the plain text and legislative history of the 
CAA, as well as the air quality goals set forth in the CAA. What 
follows is EPA's explanation of its analysis, which involves a 
discussion of the following: (1) The role of visible emissions in NAAQS 
attainment and maintenance; (2) the history of Alabama's visible 
emissions rule; (3) consideration of CAA section 110(l); (4) comparison 
of the original rule to the revised SIP-approved rule; (5) the role of 
uncertainty in EPA's analysis; and (6) the types of information that 
would be particularly useful in developing a visible emissions SIP 
revision.

1. Role of Visible Emissions in NAAQS Attainment and Maintenance

    Opacity may be defined as the degree to which emissions reduce the 
transmission of light and obscure the view of an object in the 
background. 40 CFR 60.2. Opacity is important because it provides 
information regarding pollutants visible to the eye leaving an 
emissions source. In general, the more that opaque particles pass 
through an emissions point, the more light will be blocked, thus 
increasing the opacity percentage. However, variables such as the size, 
number, and composition of the particles in the emissions can result in 
variations in the percentage of opacity.
    Historically, visible emissions have been an important tool for 
implementation of PM NAAQS and, in particular, for the implementation 
and enforcement of PM limits on sources to help attain the NAAQS. 
Visible emissions have been a useful tool to indicate overall operation 
and maintenance (O & M) of a facility and its emissions control devices 
even before modern instruments that measure PM on a direct, continuous 
basis existed. The observation of greater than normal visible 
emissions, particularly on a recurring basis, has served as an 
indication that incomplete combustion or other changes to the process 
and/or the control device had or were occurring; such changes 
frequently led to increased PM emissions. Although opacity is not a 
criteria pollutant, opacity standards continue to be used as an 
indicator of the effectiveness of emission controls for PM emissions, 
or to assist with implementation and enforcement of PM emission 
standards for purposes of attaining PM NAAQS. Opacity measurements can 
serve as an indicator of a well-maintained, well-operated source and 
that such sources should be able to achieve visible emissions that 
comply with opacity limits. For example, data submitted by one 
commenter show routine source operation with opacity of about five 
percent.\6\ Conversely, visible emissions at much higher percentages 
(such as those allowed by Alabama's revised rules), particularly on a 
recurring basis, may indicate that a source is in violation of 
applicable SIP or permit mass limits as well.
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    \6\ Alabama Power Company in Attachment T from the docket shows 
that over a three-year period its units did not exceed 5 percent 
opacity for 55.4 percent of the operating time, 10 percent opacity 
for 89 percent of the operating time, and 15 percent opacity for 
97.6 percent of the operating time. In addition, the U.S. District 
Court for the Northern District of Alabama found in 2009 that at 
TVA's Plant Colbert, Units 1-4 typical baseline opacity measured 
about 5-8 percent during normal unit operation, and Unit 5 was 
projected to operate below 5 percent opacity even with a partially 
malfunctioning control device and below 10 percent ``under extreme 
conditions that are unlikely to ever occur.'' Sierra Club v. TVA, 
592 F. Supp. 2d 1357, 1367 (N.D. AL 2009).
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    Many commenters agreed that the precise relationship between 
opacity and PM emissions was uncertain. Despite this uncertainty, there 
is a general relationship between opacity and particulate matter mass 
emissions. As a result, increases in opacity can be indicative of 
changes in emissions control device performance or source operation, 
which in turn can lead to increases in mass emissions.
    Furthermore, based on the information contained in the record for 
this action and a general lack of opacity and corresponding PM 
emissions data received to date, it is apparent that the mass of 
emissions based on short-term increases in opacity cannot be quantified 
readily for each of the 19 sources affected by the SIP revisions in the 
Alabama Submittals.\7\ There are several contributors to the 
uncertainties associated with relating mass emissions to increases in 
opacity, including: (1) Differences between combustion technology 
characteristics and fuel components; (2) differences in control 
technology types, temperatures at which they operate, and load 
characteristics; (3) the recognition that both opacity and mass 
emissions are subject to significant variability over short periods of 
time and fluctuations such that one may act independently of the other; 
and (4) differences between the mass of particles that exists at the 
point of opacity measurement by the COMS (e.g., in the stack) and the 
direct PM2.5 that forms immediately upon exiting the stack 
(that are related to fuel components more than to control technology).
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    \7\ EPA specifically requested that commenters provide any 
available concurrent data showing the PM mass emissions and opacity 
for sources affected by the SIP revision at issue, but no commenter 
supplied this information. 74 FR 50934.
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2. History of Alabama's Visible Emissions Rule

    EPA first approved Alabama's visible emissions rules into the 
Alabama SIP in 1972. 37 FR 10842, 10847 (May 31, 1972). The State 
submitted the visible emissions rules as part of its SIP for attainment 
and maintenance of the total suspended particulates (TSP) NAAQS (the 
predecessor to the PM NAAQS). The State has revised these rules three 
times in support of those goals.
    Historically, Alabama has had areas with attainment problems for 
the various PM NAAQS. Originally, EPA designated some areas in Alabama 
as nonattainment for the TSP NAAQS. In 1987, EPA replaced the TSP NAAQS 
with the PM10 NAAQS, and all areas of Alabama were 
designated as attainment for those NAAQS. 56 FR 11101 and 58 FR 67734. 
All areas of Alabama remain designated attainment for the 
PM10 NAAQS. In 1997, EPA promulgated new annual and 24-hour 
particulate matter NAAQS, using PM2.5 as the indicator. 
Effective April 5, 2005, EPA designated portions of Alabama, in the 
Birmingham and Chattanooga areas, as nonattainment for the 1997 
PM2.5 NAAQS. 70 FR 944. In 2006, EPA promulgated new 
PM2.5 NAAQS, significantly tightening the 24-hour standards. 
Effective December 14, 2009, the Birmingham area was designated 
nonattainment for the 24-hour PM2.5

[[Page 18873]]

NAAQS, as revised in 2006. The Birmingham area remains designated as 
nonattainment for both the 2006 24-hour and 1997 annual 
PM2.5 NAAQS. Chattanooga remains designated as nonattainment 
for the 1997 annual PM2.5 NAAQS. Alabama's visible emissions 
rules continue to be a part of the Alabama SIP for attainment and 
maintenance of the PM NAAQS.
    The SIP revision at issue affects the applicable visible emissions 
limits at approximately 19 stationary source facilities.\8\ These 19 
facilities include older coal-fired utilities, cement manufacturing 
facilities, and pulp and paper facilities, among others. Five of these 
facilities are located in or near nonattainment areas for the current 
PM2.5 NAAQS. Specifically, Cheney Lime and Cement Company 
(Allgood), Ernest C. Gaston Electric Generating Plant (Alabama Power 
Company (APC)), and William Crawford Gorgas Electric Generating Plant 
(APC) are located within the Birmingham nonattainment area for the 1997 
annual and 2006 24-hour PM2.5 NAAQS; Bowater Incorporated 
(Westover) is located near that area. In addition, Widows Creek Fossil 
Plant (Tennessee Valley Authority (TVA)) is located in the Chattanooga 
nonattainment area for the 1997 annual PM2.5 NAAQS. Other 
facilities affected by these visible emissions rules may also impact 
these or other nonattainment areas.
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    \8\ At this time, it is EPA's understanding that the rules at 
issue apply to 19 facilities. Due to the applicability portions of 
the rule, the rule could apply to fewer facilities over time, but 
will not likely apply to any more.
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    The geographic location of affected sources covered by the visible 
emission rules in the EPA-approved SIP is relevant. This is because (as 
is discussed more fully below) EPA interprets section 110(l) to 
prohibit approval of SIP revisions that would increase emissions of 
pollutants for which an area is designated nonattainment, in the 
absence of offsetting emission reductions or an attainment 
demonstration addressing the rule changes at issue.
    Opacity remains an important tool that states and EPA rely upon in 
establishing and enforcing PM-related standards for SIPs and other 
standards promulgated under the CAA (such as New Source Performance 
Standards (NSPS) and National Emission Standards for Hazardous Air 
Pollutants). For example, opacity measurements can serve as an 
indicator of compliance with PM emissions between PM stack tests. The 
Submittals would provide sources with the flexibility to allow for 
visible emissions of up to 100 percent opacity (previous maximum 
opacity was 40 percent) for up to 2.4 consecutive hours per day \9\ 
(previous consecutive maximum time for ``exempt'' periods per day was 6 
minutes). This change, like all SIP revisions, must be consistent with 
section 110(l).
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    \9\ The Submittals allow 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).
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3. Consideration of CAA Section 110(l) \10\
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    \10\ EPA's evaluation of this SIP revision focused on section 
110(l). If EPA were to find the revision approvable under section 
110(l) it would have to consider other issues raised by the 
commenters, including whether it is approvable under section 193. 
Further, section 110(l) applies with respect to all NAAQS in effect, 
even where EPA has not yet made designations.
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    In considering whether to approve the SIP revision at issue in this 
action, EPA must evaluate the changes embodied in the Submittals from 
the State in light of the requirements of section 110(l). Section 
110(l) of the CAA provides, in relevant part, that:

    * * * The Administrator shall not approve a revision of a plan 
if the revision would interfere with any applicable requirement 
concerning attainment and reasonable further progress (as defined in 
section 7501 of this title), or any other applicable requirement of 
this chapter.

    Congress added section 110(l) during the 1990 amendments to the CAA 
as support for the cornerstone of the SIP program in the CAA--the 
attainment and maintenance of the NAAQS. 101 Stat. 2404 (101 Pub. L. 
549) (November 15, 1990). The provision was added as part of general 
revisions to section 110 to address EPA actions on SIP revisions, in 
part responding to court cases such as a Ninth Circuit Court of Appeals 
case, Abramowitz v. EPA, 832 F.2d 1071 (9th Cir. 1987), which discussed 
Train v. NRDC, 421 US 60 (1975) (both cases addressed EPA consideration 
of SIP revisions in light of some evaluation of whether the revision at 
issue would affect the NAAQS, i.e., the impacts upon attainment or 
maintenance of the NAAQS). S. Rep. No. 101-228 (Report of the Committee 
on Environment and Public Works, United States Senate) (1990 CAA Legis. 
Hist. 8338, 8360-8363).
    By its plain language, section 110(l) applies to every SIP revision 
submitted by a state. In evaluating whether a given SIP revision would 
interfere with attainment or maintenance, as required by section 
110(l), EPA generally considers whether the SIP revision will allow for 
an increase in actual emissions into the air over what is allowed under 
the existing EPA-approved SIP. EPA has not required that a state 
produce a new complete attainment demonstration in order to make every 
revision to its SIP, provided that the status quo air quality is 
preserved. For the Submittals at issue in this action, EPA's view has 
been that if the SIP revision does not interfere with attainment or 
maintenance of the NAAQS, then it is unlikely to interfere with other 
applicable requirements. For example, if EPA concludes that emissions 
of PM allowed under the SIP are not increasing as a result of the SIP 
revision, then no additional control requirements would be required 
under section 193.
    EPA has historically interpreted section 110(l) as requiring the 
Administrator to have some basis on which to conclude that a SIP 
revision would not interfere with attainment and maintenance of the 
NAAQS, or any other applicable requirement, before EPA could approve 
the SIP revision. EPA has regularly requested such information from the 
state to support a revision, particularly where there was some 
uncertainty regarding the impacts of the SIP revision. For example, in 
2005, the State of North Carolina submitted a SIP revision that raised 
issues similar to the Alabama proposal. After considerable discussion 
between EPA and North Carolina about what revisions would be consistent 
with the requirements of section 110(l), the State submitted a SIP 
revision that addressed key issues. The rules in the revision retained 
the same number of total minutes and maximum levels of opacity allowed 
during excursion periods as under the prior EPA-approved SIP (i.e., the 
four hourly six minute exceedance periods allowed under the existing 
North Carolina SIP could occur at any time, including consecutively, 
during a 24-hour period, but the allowable maximum opacity levels 
during these periods was not increased). In particular, EPA did not 
adopt an ``average daily opacity'' approach for North Carolina, which 
would have allowed extended periods of high opacity (in excess of 40 
percent). See 70 FR 61556 (October 25, 2005). Similarly, EPA has 
proposed to disapprove a visible emissions SIP revision for Ohio in 
which that state sought to relax limitations on the number of occasions 
of excess opacity per hour, potentially allowing entire days with 
elevated opacity. The revision was submitted without a section 110(l) 
showing that the relaxation in opacity requirements would not reflect 
increased emissions

[[Page 18874]]

that would interfere with attainment and maintenance of the NAAQS or 
other requirements of the CAA. 70 FR 36901 (June 27, 2005).
    EPA recognizes that 110(l) analyses are case-specific and that the 
scope and nature of the analysis will vary, depending on the factual 
details of the SIP revision at issue. See, e.g., Hall v. EPA, 273 F.3d 
1146 (9th Cir. 2001) and Kentucky Resources Council, Inc., v. EPA, 467 
F.3d 986 (6th Cir. 2006); see also, 61 FR 16,050, 16,051 (April 11, 
1996) (actions on which the Kentucky Resources Council case were 
based).\11\ However, in the absence of a full attainment or maintenance 
demonstration, EPA has consistently required a sufficient basis in the 
record for concluding that the SIP revision would not interfere with 
attainment and maintenance of the NAAQS, or any other applicable CAA 
requirement.\12\
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    \11\ EPA's action today is consistent with both these 9th and 
6th Circuit cases addressing 110(l).
    \12\ As is discussed below, EPA's previous approval of the 
Submittals was a departure from this approach.
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4. Comparison of the Original Rule to the Revised Rule

    The substantive starting point for evaluating any SIP revision is 
to consider the differences between the current EPA-approved SIP rule 
and the revised rules being proposed by the state in the revision. Many 
of these differences were highlighted by the Petitioners and other 
parties during the public comment process on both the April 2007 
proposal and the October 2, 2009, reconsideration proposal.
    In this case, we began our analysis by comparing the rule in effect 
in the Alabama SIP at the time of EPA's April 2007 proposed action 
(hereafter ``the previous rule'') with the 2003 and 2008 Submittals 
(hereafter ``the current rule''). Under both rules, the maximum number 
of exempt six-minute periods \13\ allowed per day is the same--24; the 
maximum ``allowable average quarterly opacity'' \14\ is approximately 
the same--22 percent under the previous rule, and 21.6 percent under 
the current rule; and the maximum ``allowable average daily opacity'' 
is the same under both rules--22 percent.\15\ However, there are two 
significant differences \16\ between the previous rule and the current 
rule. The first is that the current rule allows for maximum visible 
emissions of 100 percent opacity during the exempt periods, while the 
previous rule allowed for maximum visible emissions of only 40 percent 
opacity during such periods. AAC 335-3-4-.01(4) (current rule). The 
second is that the current rule allows exceedances of the 20 percent 
SIP standard for intervals of up to 2.4 consecutive hours (i.e., up to 
24 consecutive six-minute periods per calendar day), while the previous 
rule allowed exceedances of the 20 percent SIP standard for intervals 
of only 0.1 consecutive hours (i.e., one six-minute period per 
hour).\17\ Thus, the two key differences are that the current rule 
allows for opacity to increase up to 100 percent and allows up to 2.4 
consecutive hours of opacity at that level (i.e., the ``bundling'' of 
high opacity periods) per day. A critical question, therefore, is 
whether the significant increase of the maximum allowable opacity from 
40 percent to 100 percent for such extended periods could result in 
more PM emissions were sources to take advantage of the changed limits.
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    \13\ Unless otherwise noted, this notice refers to exempt 
periods other than those provided by the previous rule for 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), which were part of the existing SIP-approved 
rule and remained unchanged under the October 15, 2008 final action 
rule.
    \14\ ``Allowable average quarterly opacity'' is not a 
traditional measurement used by states or EPA for monitoring opacity 
or for opacity standard-setting purposes. Rather, EPA first used 
this approach, which allows sources to ``average out'' periods of 
very high opacity with periods of lower opacity, in the notice 
proposing to approve the Submittals, if the rules were changed to 
limit allowable average quarterly opacity. See 72 FR 18432 
(providing instructions for calculating ``allowable average 
quarterly opacity levels.'') Subsequently, in the notice approving 
the Submittals, EPA also used the concept of ``allowable average 
daily opacity.'' 73 FR 60958.
    \15\ See previous rule AAC 335-3-4-.01(1)(b) and current rule 
AAC 335-3-4-.01(4) and 335-3-4-.01(5).
    \16\ One of the technical support documents (TSDs) provided for 
this action explains in detail the differences between the current 
and prior visible emissions rules. EPA considered all the 
differences in reaching its decision today. EPA is simply 
identifying two significant differences that are particularly 
relevant to the analysis of the submittal.
    \17\ See previous rule AAC. 335-3-4-.01(1)(b) and current rule 
AAC 335-3-4-.01(4).
---------------------------------------------------------------------------

    In EPA's original approval notice, we adopted a limited analytical 
framework for addressing this question. We did not conclude that the 
proposed change in the SIP would not result in increased PM emissions. 
Rather, we established a new metric of ``average daily opacity'' (and 
``average quarterly opacity'') and concluded that section 110(l) did 
not prohibit approval of a SIP revision that allowed significantly 
increased opacity levels for longer consecutive periods of time because 
the revision would not increase the allowable average opacity levels 
(on either a quarterly or daily basis). This analysis was focused on 
opacity and operational conditions regarding opacity as opposed to a 
focus on the relationship between opacity and PM mass emissions, in 
part because EPA did not have any useful source-specific data regarding 
the relationship between opacity and PM mass emissions at the affected 
facilities.
    EPA also concluded that the relationship between changes in opacity 
and increases or decreases in ambient PM2.5 levels could not 
be quantified readily for the sources subject to the SIP revision, and 
was particularly uncertain for short-term analyses and that the level 
of uncertainty about whether increased opacity levels allowed under the 
revision would allow increased mass emissions was sufficiently high 
that, in the absence of additional information to confirm a change in 
emissions one way or the other, section 110(l) did not prohibit 
approval of the SIP revision.
    After reconsideration, however, EPA's position is that both of the 
findings that provided the foundation for its initial approval of the 
SIP revision were not strong enough to support approval under the CAA. 
EPA concludes that, as it was described in the Submittals, the concept 
of ``average daily opacity'' is not a useful tool for evaluating 
whether the Submittals are likely to maintain current air quality, 
particularly given the lack of other limitations on opacity exceedances 
in the Submittals. One of the primary purposes of opacity limits is to 
ensure that PM control devices are operating within normal parameters. 
Thus, larger and longer exceedances of an opacity limit (e.g., 100 
percent opacity or other high opacity levels over a longer period of 
time such as 2.4 consecutive hours), which may indicate problems with a 
control device or other significant changes in emissions, are more 
significant than shorter and smaller exceedances. Under the approach of 
the revised rule, a control device could temporarily shutdown or 
malfunction, potentially resulting in 100 percent opacity, for an hour 
or two and the source could still be in compliance with the 22 percent 
average daily limit. By contrast, an opacity limit that requires 
consistent compliance at 20 percent, and allows only one excursion of 
six minutes per hour to 40 percent opacity will limit larger and longer 
excursions.
    In addition, an opacity limit that requires consistent compliance 
at 20 percent and allows only one excursion of six minutes per hour to 
40 percent opacity helps ensure that sources and their control devices 
are properly maintained, operated, and controlled. In EPA's experience, 
a source that is properly maintained, operated and

[[Page 18875]]

controlled should be capable of meeting the opacity requirements of the 
Alabama SIP without this revision. EPA is concerned that the allowance 
of higher levels and longer consecutive durations of opacity 
exceedances, even with an ``average daily opacity'' cap, would 
undermine an important purpose of the opacity limit, to ensure proper O 
& M of sources and their control devices.
    After reviewing the issues raised in the petition for 
reconsideration and additional information received during the 
reconsideration public comment period, EPA concludes that the approach 
utilized to evaluate the Submittals in the October 15, 2008, rulemaking 
resulted in a fundamentally incomplete analysis. Requiring a source to 
maintain an average daily opacity of 22 percent does not provide 
assurance that the source will generally achieve the same level of PM 
control (and emissions) as a source which meets a limit of 20 percent 
opacity, except for one six-minute period per hour at 40 percent. 
Accordingly, the approach of the prior notice, which focused solely on 
maintaining an overall average daily (and quarterly) opacity does not 
provide an adequate framework for assessing the impact of the 
Submittals on emissions and air quality, which is the touchstone of the 
analysis required under section 110(l).
    EPA did receive modeling from a variety of sources (which is 
discussed in the Response to Comments portion of today's action, 
beginning with Comment 19) which attempt to show the impact on air 
quality from the changes to the opacity requirements in the Submittals. 
In addition to EPA's discussion in the Response to Comments section, 
EPA's Technical Support Document addressing the modeling identifies the 
information gaps that prevented EPA from conducting the type of source-
specific analysis that would be necessary for completion of an adequate 
110(l) evaluation. For example, elements that are missing from the 
submitted modeling include: data from all the sources and source 
categories affected by the Alabama Submittals; a demonstration of the 
relationship between PM emissions and opacity at a particular facility 
and source-category; consideration of emissions from other sources in 
the modeled area; condensable PM data; explanation for background PM 
levels used in the evaluation; and an explanation of the use of 
PM10 as a surrogate for PM2.5; among other 
concerns. As EPA noted in its evaluation of modeling submitted during 
the first comment period:

    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.

73 FR 60961. EPA has carefully reviewed all of the modeling submitted 
and has concluded that, without source-specific data on the mass-
opacity relationship, there is not an adequate basis to model the 
impact of the revisions to the opacity rules on PM mass emissions. 
Therefore, the models are insufficient and too inaccurate to provide a 
basis for concluding that the Submittals satisfy the requirements of 
section 110(l). As discussed below, EPA would need additional data and 
information before it could conclude that this approach would not 
result in an increase of nonattainment pollutants that would interfere 
with attainment and maintenance of the NAAQS.

5. The Role of Uncertainty in EPA's Analysis

    As was noted earlier, a key issue in evaluating the Submittals is 
the element of uncertainty in the relationship between opacity and PM 
mass emissions. Many SIP submittals involve some level of uncertainty. 
EPA has never, and does not now, take the position that a small 
possibility that an attainment SIP might turn out not to result in 
attainment of the NAAQS, or to prevent a violation of the NAAQS, or 
that a SIP revision might worsen air quality, necessitates denial of a 
SIP revision. EPA recognizes that attainment planning generally 
requires a high degree of technical judgment, and often involves some 
degree of uncertainty. In EPA's prior approval, we concluded that the 
level of uncertainty concerning the impact of the SIP revisions on 
emissions of PM from sources was so great that EPA could not make a 
technical judgment as to whether or not approval of the Submittals 
would likely interfere with attainment and maintenance of the NAAQS or 
any other applicable requirements. In the face of such uncertainty, EPA 
concluded that section 110(l) did not prohibit the approval of the 
revisions at issue. After reconsideration, EPA has concluded that its 
traditional, and more precautionary, approach to interpreting section 
110(l) is appropriate.
    There is a general relationship between opacity and PM emissions 
such that an increase in opacity means the concentration of smaller 
particles, larger particles, or both, increases. See, e.g., Malm, 
William C., ``Introduction to Visibility,'' Cooperative Institute for 
Research in the Atmosphere, May 1999 at Chap. 2, p. 8. However, because 
increases in the quantity of smaller particles may be accompanied by 
decreases in the quantity of larger particles, and vice versa, changes 
in opacity do not necessarily reflect corresponding changes in the mass 
of PM emissions. While source-specific relationships between opacity 
and PM emissions may be obtained through testing, they can be 
influenced by a variety of circumstances such as fuel compositions and 
types of equipment malfunction that may occur. Therefore, while changes 
in opacity generally indicate changes in PM emissions, there is 
uncertainty about quantifying the specific level of PM emissions 
associated with varying levels of opacity.
    EPA has previously explained the elements of that uncertainty in 
its proposed reconsideration action. 74 FR at 50933. One key element is 
the recognition that both opacity and mass emissions are subject to 
significant variability of short periods of time and fluctuations such 
that one may act independently of the other. Id. Thus, EPA concludes 
(and many commenters also acknowledged) that there is a relationship 
between opacity and PM such that periods of high opacity can result in 
increased PM emissions, which in turn can cause or contribute to a PM 
NAAQS violation. We can say with certainty that periods of high opacity 
would cause interference with the PM NAAQS in some circumstances. What 
EPA does not know is precisely when such changes in opacity would cause 
the interference, particularly for a variety of source types. This is 
the unknown element discussed in detail in EPA's proposal and this 
final action.
    Section 110(l) was intended to allow SIP revisions in the absence 
of full attainment demonstrations, but EPA's view is that Congress 
would not have wanted EPA to approve SIP revisions where EPA lacked not 
only an attainment demonstration but also any basis for concluding that 
the SIP revision would not interfere with attainment or maintenance of 
the NAAQS, and other applicable requirements. Accordingly, consistent 
with our past practice in considering SIP revisions, EPA concludes that 
there must be either a contemporaneous attainment demonstration or some 
other basis for concluding that a SIP revision will not interfere with 
attainment, and that uncertainty alone is not a sufficient

[[Page 18876]]

basis for approving a SIP revision. Moreover, EPA has also concluded, 
following reconsideration, that there is a sufficient likelihood that 
the SIP revision at issue in this action could allow increased mass 
emissions over what would have been allowed under the previously 
approved SIP rule and that, in the absence of additional information or 
limitations, the revision is not approvable under section 110(l). As 
noted by commenters during the reconsideration process, although a 
precise correlation between mass emissions and opacity for an 
individual source can be difficult to ascertain, the changes 
contemplated in the Submittals are such that changes in emissions, 
including increases, are possible under the opacity levels allowed by 
the SIP revision. Given the location of affected sources within 
nonattainment areas, EPA has concluded that additional emissions from 
such sources would interfere with attainment and maintenance of the 
NAAQS in these areas.
    EPA recognizes that there are circumstances in which a source will 
record opacity levels in excess of a 20 percent standard without 
necessarily increasing its mass emissions, but there are also many 
circumstances where increased opacity levels are associated with 
increased mass levels. The Submittals would provide sources with the 
flexibility to allow for visible emissions of up to 100 percent opacity 
for up to 2.4 consecutive hours per day. The degree of operational 
flexibility associated with the Submittals is such that EPA concludes 
that the opacity limits in the Submittals are likely overall to allow 
increased PM emissions. Even though every instance of operation at 
greater than 20 percent opacity may not result in increased emissions, 
and though EPA cannot precisely quantify the effect of approving the 
Submittals on the information in the record, it is reasonably 
foreseeable that approving the Alabama Submittals would allow increased 
mass emissions, for at least some sources and under at least some 
conditions, over the PM emission levels that would have been allowed 
under the previously approved SIP rule. Given this situation, section 
110(l) requires disapproval of the Submittals absent additional 
limitations which would significantly diminish the likelihood that mass 
emissions increases will occur. The result of the disapproval is simply 
that Alabama's previous EPA-approved visible emissions rule will become 
the federally-enforceable rule in the SIP (although EPA urges that 
Alabama take any regulatory action necessary to avoid having a State-
effective rule that is different from the SIP-approved rule).

6. Information Regarding Development of Visible Emissions SIP Revisions

    In EPA's October 2, 2009, reconsideration proposal following 
reconsideration, EPA included a section entitled, ``III. What 
Additional Information Would EPA Like To Receive?'' 74 FR 50934. EPA 
specifically requested information on the nature of the relationship 
between opacity and PM mass emissions over both the short and long term 
and when the opacity and PM mass emissions may have a predictable 
relationship to one another. Id. EPA also requested source-specific 
data from Alabama facilities affected by the Submittals. EPA also 
included a bulleted list of more specific types of information that 
could assist in conducting an analysis on the impacts of a SIP revision 
on the air quality of the affected area (i.e., a 110(l) analysis). Id. 
Providing guidance on development of a general visible emissions SIP 
revision is difficult because opacity and visible emissions are most 
easily evaluated in a source-specific context. However, states may 
consider the following information useful.
    As a general matter, states may find it instructive to look at 
visible emissions SIP revisions that EPA has approved. An example is 
the North Carolina approval previously referenced in this rulemaking. 
70 FR 61556. As was noted earlier in this rulemaking, there are two key 
differences between the North Carolina action and the Alabama 
Submittals now being disapproved. First, the North Carolina action did 
not allow additional minutes of opacity exceptions. Second, the North 
Carolina action did not change the percentage of opacity allowed during 
the exception periods.
    More generally, EPA expects that providing assurance that a source 
will comply with a rule that allows no more than one 6-minute 
exceedance per hour and opacity readings no greater than 40 percent 
clearly requires more effective control equipment and/or operating 
procedures than it takes to assure a source will comply with a rule 
that allows longer consecutive periods of exempt opacity excursions and 
at higher opacity levels. Opacity and PM emissions are related closely 
enough that control equipment effective enough to meet the more 
stringent opacity standard (in terms of the number of consecutive 
excursions allowed and the level of opacity excursions allowed) will 
also provide a greater level of PM emissions control. Due to the 
importance of first understanding the relationship between opacity and 
PM emissions at the affected sources, source-specific SIP revisions 
have historically been used by most states in developing different 
visible emissions standards for a source, particularly when those 
standards are less stringent than existing standards. Source-specific 
SIP revisions allow for the ability to analyze the PM/opacity 
relationship and establish an appropriate opacity limit that will not 
impact the NAAQS. The technical analysis for such rule changes would 
likely involve collection of parallel mass and opacity data for the 
source in question. If that information indicates that there will be 
increases in PM mass emissions or opacity, then further analysis would 
be required to ensure that the increased emissions associated with the 
increased opacity (or rule change at issue) will not interfere with 
attainment, reasonable further progress, or any other applicable 
requirement of the CAA (the 110(l) factors), for that particular source 
and locale. Further, a more definitive modeling assessment of the 
effect of any proposed rule would include the representative range of 
emission rates and/or conditions producing 100 percent opacity for each 
type of source affected by the rule.
    When source-specific information is available, the uncertainty 
about the relationship between opacity and mass, and the implication of 
the changes in opacity on PM emissions, is reduced and there may be a 
basis upon which to make an informed judgment about the impacts of the 
change with respect to section 110(l). Further, source-specific actions 
are much more discrete since they typically apply at a particular unit 
of a particular facility, thus eliminating the need to evaluate the 
statewide impact of the change. EPA has undertaken source-specific 
opacity revisions. See, e.g., 66 FR 33027 (June 20, 2001) (approving a 
source-specific revision affecting 14 units in Alaska). Similarly, a 
focus on a particular source category may also allow for more specific 
understanding regarding the relationship between opacity and PM 
emissions at the affected facilities and the rule's overall impact to 
air quality. 73 FR 36485 (June 27, 2008) (proposing disapproval of 
source-category specific revision; notice explains how a source-
category revision may be developed).
    EPA is not suggesting that every revision to an opacity standard 
requires source-specific analyses. If a submission provides a 
sufficient basis for EPA to conclude that changes to a visible 
emissions requirement will not result in

[[Page 18877]]

increased PM emissions in a nonattainment area over what would have 
been allowed under the previously approved SIP rule (or otherwise 
interfere with any applicable requirement of the CAA), then EPA 
anticipates that it would be approvable under section 110(l). 
Ultimately, the key issue that must be addressed in any 110(l) analysis 
of an opacity SIP revision is an evaluation regarding the impact of 
that revision on PM emissions and the NAAQS. As was noted earlier, 
because Alabama's Submittals were voluntary revisions to the SIP and 
not mandated, Alabama has no obligation to develop another visible 
emissions revision.

III. Response to Comments

    The following are EPA's responses to the significant adverse 
comments on EPA's October 2, 2009, proposal. EPA is obligated to 
respond to adverse comments received and thus, has reviewed the 
comments that were adverse to a disapproval of the State's SIP 
revisions. EPA is now responding to those comments. Many of the 
comments overlapped or were redundant, so in order to assist with 
readability of the responses, we have organized the comments and 
responses into subject-matter groupings identified below.

1. Basis for Reconsidering the 2008 Final Action
2. Relationship Between Opacity and PM Emissions
3. Modeling
4. Relative Stringency of Previous Rule (Pre-2008 Final Action) to 
Current Rule (Post-2008 Final Action)
5. Attainment and Maintenance of the PM NAAQS (PM10 and 
PM2.5) and Data Submitted in Response to October 2009 
Reconsideration Proposal
6. Impact of Uncertainty in These SIP Revisions
7. Applicability of CAA Sections 110(l) and 193 to This Action
8. CAA Section 110(l) ``Demonstration'' of Non-Interference With the 
NAAQS and Other Requirements
9. Use of COMS and Need for Exemptions
10. Relationship of SIP Revisions to 40 CFR Section 51.212
11. Relationship of SIP Revisions to the Compliance Assurance 
Monitoring (CAM) Rule
12. Relationship of SIP Revisions to Sierra Club v. EPA, 551 F.3d 1019 
(D.C. Cir. 2008), and the Vacatur of Certain Provisions in 40 CFR Part 
63
13. Relationship of SIP Revisions to Reasonably Available Control 
Technology (RACT)
14. Other Exemptions in the Alabama SIP Related to Visible Emissions

1. Basis for Reconsidering the 2008 Final Action

    Comment 1. Commenters argued that because EPA's October 2, 2009, 
reconsideration proposal notice did not select an option, or at least 
disclose to the public which option EPA preferred, EPA's interpretation 
of the relevant CAA provisions and their application to the situation 
here will be entitled to no deference upon judicial review. Also, the 
commenters asserted that their ability to comment on the proposal is 
hamstrung by EPA's failure to articulate which option EPA would choose.
    Response 1. EPA does not agree with commenters' characterization of 
the October 2, 2009, proposed rulemaking. That proposal described two 
alternative actions in detail--including the technical, legal, and 
policy bases for each of the respective actions. EPA provided 
sufficient information for each alternative for commenters to 
participate meaningfully and for either alternative proposal to be 
finalized, depending upon what additional information was developed as 
a result of the reconsideration. EPA has previously used the 
alternative proposal option when dealing with a particularly complex 
rulemaking (see, e.g., proposal regarding California-Imperial Valley 
Planning Area, 66 FR 42187 (August 10, 2001)). In this case, EPA's 
interest in ensuring public comment on the two primary options was best 
achieved through the alternative proposals. There is no indication of 
any commenter being unable to provide meaningful comments. Numerous 
commenters provided substantive comments on both of the two proposals. 
The substance of the commenters' own comments reflect that they were on 
notice of the factual and legal issues relevant to the reconsideration.
    Comment 2. Commenters asserted that there is no new record evidence 
provided by EPA, Petitioners, or other interested parties in order to 
support the second petition for reconsideration of EPA's approval of 
the SIP revision in the October 2008 final action.
    Response 2. EPA's authority to reconsider a SIP rulemaking derives 
from both the Administrative Procedures Act (APA) section 553(e) as 
well as authority in the CAA. The APA provides the opportunity for any 
person to ``petition for the issuance, amendment, or repeal of a 
rule.'' 5 U.S.C. 553(e). The APA does not explicitly limit this right 
based on new evidence or any other limitations alleged by commenter. 
Even if there were such a limitation, EPA disagrees that the second 
petition for reconsideration did not raise issues that warranted 
reexamination of the factual and legal basis for the October 2008 
action.
    Comment 3. Commenters argued that the CAA does not authorize EPA to 
continue to entertain petitions for reconsideration ``indefinitely'' 
after a specific CAA process has been followed and reconsideration has 
been denied. According to the commenters, the CAA allows EPA to 
``call'' an approved State SIP for legal deficiencies, but does not 
allow EPA to continue to reconsider its actions on a state-submitted 
SIP revision after the revision is approved. Commenters also argued 
that EPA lacks authority to reverse its approval of the SIP revisions 
because EPA may only change its standard for review of SIP revisions 
under section 110(l) prospectively--i.e., EPA may only apply an 
allegedly new reading of section 110(l) to new state requests for SIP 
revision. The commenters further argued that any request for 
reconsideration of a final SIP approval must follow the procedures 
identified in CAA section 110(k)(5) for seeking a change to a 
previously approved SIP revision (noting that section 307 does not 
apply and section 553(e) of the APA cannot be used to bypass 110(k)).
    Response 3. EPA disagrees with the commenters' views of EPA's 
authority to reconsider rulemakings under these circumstances. An 
administrative agency has the authority to reconsider its decisions, 
unless Congress specifically limits the agency's discretion to do so. 
See, e.g., Gun South, Inc. v. Brady, 877 F.2d 858, 862 (11th Cir. 1989) 
(holding that agencies have implied authority to reconsider and rectify 
errors even though the applicable statute and rules do not provide 
expressly for such reconsideration). The DC Circuit Court recently 
affirmed this authority in New Jersey v. EPA, 517 F.3d 574 (D.C. Cir. 
2008), where it explained that an agency normally can change its 
position and reverse a prior decision but that in the case before it, 
Congress limited EPA's ability to remove sources from the list of 
hazardous air pollutant source categories, once listed, by requiring 
EPA to follow the specific delisting process at CAA section 112(c)(9). 
See also, e.g., Trujillo v. General Electric Co., 621 F.2d 1084, 1086 
(10th Cir. 1980) (``Administrative agencies have an inherent authority 
to reconsider their own decisions, since the power to decide in the 
first instance carries with it the power to reconsider''). EPA recently 
applied this approach in connection with California conformity

[[Page 18878]]

SIPs. EPA had approved the SIPs based on a mobile source model that was 
current at the time of EPA's approval. EPA proceeded to update the 
mobile source model, but under the previous SIP approvals, conformity 
decisions would continue to be made on the basis of those previous SIP 
approvals, and would not take into account the updates to the mobile 
source model. To remedy this problem, EPA conducted a rulemaking that 
revised the previous SIP approvals so that they were limited to the 
period before States submitted, and EPA found adequate, the mobile 
source budgets in new SIPs based upon the update of the mobile source 
model. See 74 FR 55292, 55342 (October 27, 2009) (discussing EPA's 
inherent authority to reconsider SIP actions). See also 73 FR 21528 
(August 22, 2008) (EPA final action on reconsideration of previous 
Georgia SIP action).
    The commenters questioned EPA's authority to reconsider a SIP 
action and appear to suggest that EPA's authority is limited to only a 
SIP ``call'' under section 110(k)(5) of the CAA. The SIP call process, 
however, is a distinct and separate authority that Congress has given 
to EPA for use when EPA determines that a current SIP is substantially 
inadequate to attain or maintain compliance with the CAA requirements. 
See, e.g., Sierra Club v. Georgia Power Company, 443 F.3d 1346, 1348 
(11th Cir. 2006) (describing the separate revision provisions under the 
CAA and the SIP call process generally). The SIP call process was not 
intended to be the sole means of revising the SIP and does not displace 
EPA's authority to reconsider its approval.\18\ While the two processes 
may be complementary, the authority to reconsider an action and the 
authority to issue a SIP call are not mutually exclusive, and one or 
the other may be appropriate in different circumstances.
---------------------------------------------------------------------------

    \18\ In addition to its SIP call provisions, the CAA also 
includes provisions for the correction of errors in the SIP. See CAA 
section 110(k)(6). EPA notes that the process it has used for 
reconsidering and disapproving this SIP revision is entirely 
consistent with the process required under section 110(k)(6).
---------------------------------------------------------------------------

    As the commenters correctly noted, EPA's approval of a SIP revision 
is not subject to the rulemaking requirements of the CAA section 307(d) 
because it does not fall within the enumerated categories in section 
307(d)(1) of the CAA. Section 307(b)(1), to which a SIP revision 
rulemaking is subject, contemplates the ``filing of a petition for 
reconsideration by the Administrator of any otherwise final rule or 
action.'' 42 U.S.C. 7607(b)(1). Courts have also found that EPA must 
follow the rulemaking requirements of the APA when evaluating a SIP 
submission (see, e.g., Hall, 273 F.3d at 1161), including section 
553(e). Finally, the very nature of a SIP is that it is not a static 
document; it is regularly revised to account for new EPA standards and 
new emissions reduction technologies. 42 U.S.C. 7410(a)(2)(H).
    Furthermore, EPA notes that the SIP revision at issue did not take 
effect by its own terms until after the date on which EPA granted the 
second petition for reconsideration. No sources affected by the 
revisions to the Alabama SIP should have been required to alter their 
facilities or their operations in reliance on the prior EPA approval. 
EPA's view is that a source that is properly maintained, operated and 
controlled should have no difficulty complying with either the pre-
existing or the revised version of visible emissions rules in the SIP, 
or even complying simultaneously with both versions of the SIP, which 
suggests that the reconsideration process should not have been 
disruptive for any source. In the present case, EPA concluded that 
reconsideration of its approval of the Submittals was necessary to 
ensure that the final decision was consistent with the plain text and 
legislative history, and air quality goals of the CAA, given the facts 
at issue in this situation. While the result of EPA's action today is 
that Alabama's Submittals are disapproved, the effective date for such 
disapprovals will be the effective date of this final action. Thus, 
there is nothing retroactive about today's final action.
    Comment 4. Commenters argued that if EPA reverses its approval of 
the Submittals now, that would be arbitrary, contrary to EPA's 
statutory authority and its responsibility to implement the CAA, and in 
violation of EPA's ``delegation commitment'' to Alabama under the CAA.
    Response 4. As a point of clarification, Alabama is authorized to 
implement certain portions of the CAA through its SIP. Commenters do 
not explain the ``delegation commitment'' reference. Such terminology 
is inapposite as the majority of CAA programs are ``authorized,'' not 
``delegated,'' particularly with regard to those embodied in a SIP. 
Some CAA programs, such as section 112, are routinely ``delegated'' by 
EPA to states; however, section 112 programs are not SIP programs. 
EPA's responsibility to implement the CAA extends to ensuring that its 
decisions are based in the CAA and its implementing regulations. In the 
instant action, EPA is reversing a previous approval decision because 
after reconsideration, EPA has concluded that a disapproval is required 
based on known technical information (as opposed to uncertainty) and an 
interpretation of section 110(l) that is most consistent with the plain 
text and legislative history of the CAA, as well as the air quality 
goals set forth in the CAA. As was explained above, EPA's 
reconsideration process is well grounded in statutory authority.
    Comment 5. Commenters asserted that EPA's reconsideration proposal 
notice does not provide any information about the legal authority that 
the Agency believes justifies its action. The commenters further argued 
that it is incumbent upon the Agency to disclose the legal basis upon 
which it proposes to act and to provide the public with the opportunity 
to comment on that asserted basis, and that without such an explanation 
from EPA, the October 2, 2009, proposal notice is deficient and does 
not provide an adequate basis upon which the Agency can lawfully take 
action.
    Response 5. EPA does not agree with commenters' assessment. The 
October 2, 2009, reconsideration proposal includes two alternative 
options for final action--both based upon application of section 110(l) 
of the CAA. Section 110(l) applies to all SIP revisions and limits 
EPA's legal authority to approve revisions to existing EPA-approved SIP 
provisions. The reconsideration proposal notice explained the 
alternative proposed actions as well as the interpretation of section 
110(l) that would support each of the alternatives. The substance of 
the comments reflects that the commenters were in fact on notice of the 
factual and legal issues that EPA raised for reconsideration.
    Comment 6. Commenters asserted that certain documents received in 
response to a Freedom of Information Act (FOIA) request do not support 
the reopening of the public comment period.
    Response 6. As was explained earlier, there is no prohibition on 
EPA's authority to review a final action and allow for a new public 
comment period on that action. EPA has provided the basis of the 
reconsideration of the October 15, 2008, final rule--the CAA and the 
APA. Whether documents obtained through a FOIA support EPA's 
reconsideration, in the opinion of the commenter, is not relevant.
    Comment 7. Commenters asserted that EPA appears to be considering a 
``policy change'' in how it interprets and applies section 110(l) in 
the reconsideration process. Commenters argued that if EPA wants the 
State to amend its approved SIP to reflect revised EPA policy on 
section 110(l), EPA must act under section 110(k)(5) of the CAA and not 
through a ``unilateral'' notice and

[[Page 18879]]

comment process. Commenters asserted that they are aware of no other 
situation where EPA has proposed to act in this manner to ``withdraw'' 
a final approval of a SIP revision.\19\
---------------------------------------------------------------------------

    \19\ EPA notes APC's request that should EPA take final acting 
disapproving Alabama's SIP revisions, that EPA stay its disapproval 
action pending litigation (APC Comments, pp. 10, footnote 2). EPA is 
not acting on this request through this final action.
---------------------------------------------------------------------------

    Response 7. EPA's interpretation of 110(l) that is outlined in this 
final action is consistent with EPA's historic interpretation of 
110(l), the plain text of the CAA, and the legislative history of the 
CAA (as well as court opinions that have considered 110(l)). EPA's 
decision is based on its re-evaluation of the likelihood that approval 
of the Submittals will result in increases of allowable PM emissions. 
In amending its previous action, EPA is placing greater weight on the 
technical aspects of the SIP Submittals that are known to have the 
potential for adverse impacts on the NAAQS as a result of allowing 
greater levels and durations of opacity exceedances. This change does 
not represent a policy shift, but rather, an analytical reconsideration 
of what decision is most supported by the CAA, given the facts at issue 
in this rulemaking. Moreover, EPA's reconsideration process in this 
action was far from ``unilateral.'' By reopening the rulemaking for 
additional public comment, and setting forth the legal, technical, and 
policy bases for that alternative outcomes in the reconsideration 
process, EPA sought to ensure that the public had an opportunity to 
comment and review the possible options.
    Ironically, if anything, the SIP call process apparently preferred 
by commenters is more ``unilateral'' in that such a process is 
initiated after EPA has concerns that an existing SIP is substantially 
inadequate and often requires a state to take action to revise its SIP 
following EPA's final action on the SIP call. Here, EPA's disapproval 
will result in a rule coming back into effect that was in effect for 
years. Alabama will not be required to submit a revised SIP revision. 
Further, as explained above, EPA has used the alternative proposal 
approach in the past. While the approach is not appropriate in all 
regulatory actions, it serves an important purpose of seeking public 
comment in the unusual circumstance in which two potentially 
supportable decisions exist and additional information or input from 
the public may be helpful to EPA in making a final decision.
    Comment 8. Commenters stated that EPA's prior analysis of the SIP 
revision remains sound and that there is no basis for reversing the 
conclusions of that analysis. According to the commenters, the rigors 
of the prior SIP revision process insured that the concerns raised by 
the Petitioners have already been heard and considered by both ADEM and 
EPA multiple times. The commenters argued that the petition for 
reconsideration raised no issues that were not or could not have been 
raised during the prior rulemaking process. Therefore, the commenters 
argued that reversing the prior approval of Alabama's Submittals at 
this point and in this manner would not only be an abuse of EPA's 
authority under the CAA, it would be the height of arbitrary and 
capricious Agency action.
    Response 8. EPA does not agree with the commenters' assessment. For 
the reasons described in this final notice, EPA has determined that 
reconsidering its prior approval and seeking additional notice and 
comment on the factual and legal issues raised by the Petitioners was 
an appropriate action. In reversing its prior approval, EPA has 
concluded that disapproval is necessary pursuant to the plain text of 
the CAA, its legislative history, and the air quality goals described 
therein. EPA appreciates that there has been substantial discussion 
about the merits of the Submittals, including various opportunities for 
public comment. Ultimately, however, when weighing alternatives, EPA's 
final decision must be the one that is most consistent with the CAA, 
even if that decision is reached through a reconsideration process. EPA 
has already addressed its authority to review the October 15, 2008, 
final action in response to comments above.
    Comment 9. Commenters asserted that in granting the second petition 
for reconsideration and re-opening the rulemaking for further public 
comment, EPA ignores the lack of a legal basis for reconsideration, its 
earlier rejection of AEC's arguments for reconsideration on the merits, 
and its thorough review and technical analysis of the effect of these 
SIP revisions during the earlier rulemaking itself. According to the 
commenters, reconsidering a SIP approval sets a poor precedent and 
undermines regulatory certainty and the integrity of EPA's rulemaking 
processes.
    Response 9. EPA does not agree with commenters' assessment. To the 
contrary, the reconsideration process has ensured that EPA has left no 
issue unconsidered in its analysis of the Submittals. EPA's final 
action on the Submittals, while amended from its previous action, is 
strongly grounded in the CAA, the APA, and sound science. This action 
furthers the purposes of the CAA, is based on the substantive 
requirements of the CAA, and follows the rulemaking requirements of the 
CAA and the APA. Thus, the action supports regulatory certainty and the 
integrity of SIP process. See, e.g. 73 FR 21528 (August 22, 2008) (EPA 
reconsideration of Georgia SIP action). Indeed, the fact that the CAA 
and the APA provide bases for reconsidering regulatory decisions 
demonstrates that Congress expected EPA to take necessary action to 
revise its actions when a party raises factual or legal issues that the 
Agency finds justify reconsidering such actions.
    Comment 10. Commenters questioned why EPA granted the petition for 
reconsideration of the approval of Alabama's Submittal because the 
Petitioners have provided no new information.
    Response 10. As was discussed above, the APA does not restrict 
EPA's authority to reconsider a rule to a specific record or timeframe. 
EPA was petitioned for reconsideration of a rule and EPA granted that 
reconsideration because it concluded that the petition raised factual 
and legal issues that justified further evaluation. The second petition 
for reconsideration raised numerous reasons why EPA's October 15, 2008, 
final action should be reconsidered, including several reasons not 
identified in the first petition for reconsideration. Thus, commenters' 
characterization of the second petition for reconsideration as 
providing no new information is also not correct.

2. Relationship Between Opacity and PM Emissions

    Comment 11. Commenters asserted that data submitted to EPA show 
that there is no reliable or direct correlation between opacity and PM 
emissions. In addition to several sources of uncertainty in the 
relationship between changes in opacity and increases or decreases in 
PM2.5 levels cited by EPA in the April 12, 2007, proposal 
notice, the commenters argued that other variables affecting the 
relationship of opacity and PM mass emissions include stack diameter, 
stack gas temperature, particle density (a function of coal type), and 
flue gas water vapor content. The commenters argued that many, if not 
most, of these variables are beyond the control of source operators. 
Therefore, the commenters stated that while opacity can serve as an 
indicator of whether the boiler and related pollution control equipment 
at a specific source are well-controlled and well-operated, changes to 
opacity of emissions,

[[Page 18880]]

including changes to the SIP limits applicable to opacity in a SIP, 
cannot be presumed to have any direct effect on ambient concentrations 
of PM.
    Response 11. EPA generally agrees with commenters that there is 
inherent uncertainty in the precise relationship between opacity and 
ambient concentrations of PM, although we note that some variables are 
less likely to vary during a single source's operation (as opposed to 
among different sources). EPA also agrees (as a general matter) with 
commenters' statements that opacity is useful as an indicator of a 
source's operations and control technology. Moreover, opacity can be a 
reliable indicator of PM emissions when appropriate source-specific 
testing is carried out and correlations are established for the 
particular source, operating characteristics, and fuel supply.
    EPA disagrees, therefore, that increases in opacity of emissions 
per se could not reflect any increases in mass emissions under any 
circumstances, in particular in the case of the significant increases 
in the percentage opacity and the duration of excursion time at issue 
in these SIP revisions. This comment highlights the importance of 
ensuring that the final decision made by EPA to approve a SIP revision 
is based on a reasoned application of that knowledge within the 
confines of the CAA.
    Comment 12. Commenters argued that available data continue to 
demonstrate there is no reliable, generally applicable relationship 
between opacity and the PM NAAQS. The commenters asserted that previous 
technical studies submitted by APC in the rulemaking confirm this lack 
of correlation. The commenters referred to prior comments for the 
assertion that: ``Because opacity is dependent on so many factors, 
there is no general relationship between opacity and particulate 
loading.''
    Response 12. EPA agrees that opacity data from different individual 
sources are very specific to the source and to the manner in which it 
is being operated for the period over which data is collected. In other 
words, source operation affects data produced by the source. Thus, EPA 
and others must consider not only the data on opacity and PM, but also 
the details regarding the facility and its operating characteristics as 
part of developing an opacity/PM correlation. As a result, such data 
from one facility may be of limited value in extrapolating reliable 
conclusions about emissions from another facility. However, EPA expects 
that sufficiently high increases in opacity up to 100 percent for 
extended periods can represent some impact on PM emissions from the 
sources affected by the rules at issue in the Alabama SIP revisions. As 
noted by comments received through the reconsideration process, 
although the precise correlation between the mass and opacity of 
emissions may vary, significant increases in opacity to its highest 
measurable level at the same source are likely to result in additional 
PM emissions from that source. Given that several sources are located 
in and near nonattainment areas, such additional emissions are 
inconsistent with the prohibition of section 110(l) on SIP revisions 
that will interfere with attainment and maintenance of the NAAQS.
    Comment 13. One commenter asserted that EPA's prior conclusion that 
greater opacity does not necessarily mean greater PM emissions is 
entirely reasonable.
    Response 13. EPA appreciates commenters' position on this issue--
the uncertainty inherent in the relationship between opacity and PM is 
discussed at length in this final action. While EPA agrees that greater 
opacity does not necessarily (in all circumstances) mean greater PM 
emissions, EPA does expect that some periods of greater opacity 
(particularly of high opacity for longer periods of time) are likely in 
at least some circumstances to be accompanied by greater PM emissions.
    Comment 14. A commenter agreed that it is difficult to accurately 
characterize differences in direct PM2.5 emissions 
attributable to short-term increases in opacity and further commented 
that: (1) The type of event causing the short-term increase in opacity 
will most probably have an effect on any direct PM2.5 
emissions differences associated with the event, and (2) based on the 
cumulative size distribution table in AP-42 (Compilation of Air 
Pollutant Emission Factors), any increase in PM emissions associated 
with short-term increases in opacity would most likely occur in 
particle sizes larger than direct PM2.5.
    Response 14. Commenter appears to refer to Table 1-1.6, 
``Cumulative Particle Size Distribution and Size-Specific Emission 
Factors for Dry Bottom Boilers Burning Pulverized Bituminous and 
Subbituminous,'' which is found in Chapter 1 of EPA's AP-42, 
Compilation of Air Pollutant Emission Factors (http://www.epa.gov/ttn/chief/ap42/). This table suggests that for units having pollutant 
emissions controlled by electrostatic precipitators (ESPs), 
PM2.5 accounts for only 29 percent of total PM emissions. 
EPA agrees the type of event causing an increase in opacity of 
emissions may have an effect on the size distribution of PM emissions. 
However, EPA disagrees that increases in PM emissions associated with 
increases in opacity would most likely occur in particle sizes larger 
than 2.5 micrometers in aerodynamic equivalent diameter, since the 
circumstance that causes an opacity increase could occur while a PM 
control device is operating properly, as described by the value 
contained in the AP-42 table, or while a PM control device is not 
operating properly, a condition not described in the AP-42 table. The 
uncertainty regarding the impact of opacity increases on PM emissions 
is further complicated because particles approximately 1.0 micrometer 
in diameter have greater potential for increasing opacity than larger 
particles. See, e.g., Malm, William C., ``Introduction to Visibility,'' 
Cooperative Institute for Research in the Atmosphere, May 1999 at Chap. 
2, p. 8. Thus, for the increases in opacity contemplated in the SIP 
revisions at issue in this rulemaking, EPA is concerned that this 
increased opacity would probably include additional particles of the 
very types that would be problematic for purposes of attaining and 
maintaining the PM2.5 NAAQS.
    Comment 15. Commenters argued that with regard to EPA's request for 
additional information addressing the relationship between opacity and 
PM emissions generally, only the relationship between opacity and 
direct PM2.5 would be relevant to the situation at hand, and 
that this information would be virtually impossible to obtain due to 
the inclusion of larger particles which are an inevitable part of any 
effluent gas stream.
    Response 15. EPA agrees that information concerning the 
relationship between opacity and PM2.5 emissions from a 
facility would be most relevant for purposes of evaluating impacts on 
the PM2.5 NAAQS, but EPA notes that no commenter provided 
such data, despite EPA's specific request for such specific data. 74 FR 
50934 (October 2, 2009). EPA disagrees that this information would be 
virtually impossible to obtain. By way of example, some sources are 
obtaining and reporting these data as part of the current electrical 
utility maximum achievable control technology (MACT) rule information 
collection request. Also, under section 110(l) of the CAA, EPA may not 
approve revisions to SIP if the revisions would interfere with any 
applicable requirement concerning attainment and reasonable further 
progress (RFP), or any other applicable requirement of the CAA. Because 
there are also NAAQS for PM10, states and EPA must also 
consider potential

[[Page 18881]]

impacts of increases of larger particles if increased opacity were to 
include the emissions of larger particles from a source as the 
commenter asserted. For 110(l) purposes, analysis of a SIP revision 
must include all of the current NAAQS, to the extent that the changes 
in the SIP revision could affect such NAAQS. With respect to this 
action, EPA has only focused on the potential impacts of the SIP 
revision on the PM2.5 NAAQS because those are the standards 
that EPA anticipates are most implicated by the increases in opacity at 
issue.
    Comment 16. Commenters argued that although an increase in opacity 
can be a good indication that PM emissions at the stack also are 
increasing, the magnitude of mass emissions relative to any one opacity 
value and the increase in mass emissions relative to increase in 
opacity generally are not quantifiable. Accordingly commenters asserted 
that an increase in opacity would provide no information regarding 
emission levels of PM2.5, as opposed to PM10 or 
total PM, and argued that any correlation between opacity and PM would 
have to be source specific, and even then, uncertainties remain. The 
commenters also criticized EPA's information on opacity and PM, noting 
that the charts included in the docket do not contain sufficient 
information to evaluate the relationship between opacity and PM.
    Response 16. EPA agrees that an increase in opacity can be a good 
indication that PM emissions at the stack also are increasing. It is 
for this reason that we are disapproving the SIP revision embodied in 
the Submittals, even though the magnitude of mass emissions relative to 
any one opacity value and the increase in mass emissions relative to 
increase in opacity generally are not quantifiable. EPA also agrees 
with the commenters that a correlation between mass and opacity can be 
derived at a specific source, and EPA has in the past approved SIP 
revisions that relied on such correlations with sufficient technical 
analysis.
    EPA disagrees, however, that information about opacity increases 
provides no information regarding PM2.5 emissions 
specifically. Rather, information about opacity increases without 
concurrent PM2.5 emissions data or an established 
correlation between opacity and PM2.5 emissions cannot be 
expected to yield definitive information concerning increases in 
PM2.5 emissions. The memorandum in the docket, EPA-R04-OAR-
2005-AL-0002-0064, provides the information known to EPA about the 
charts referenced by the commenter, EPA-R04-OAR-2005-AL-0002-0045 and 
EPA-R04-OAR-2005-AL-0002-0047. Further, the charts provided in the 
docket demonstrate the inherent uncertainty in the relationship between 
opacity and filterable PM mass emissions by showing a range of mass 
emission rates associated with a single opacity value and a range of 
opacity values associated with a single mass emissions rate. However, 
uncertainty about the precise correlation between mass and opacity as a 
general matter, does not mean that opacity increases never represent 
concurrent increases in the mass of PM emissions from a source. To the 
contrary, given the large increases in maximum allowable opacity and 
for the periods of time at issue in the SIP revision contemplated in 
the Submittals, EPA expects that it is likely that there could be 
increases in mass emissions.
    Comment 17. Commenter disputed the relationship between opacity and 
PM mass emissions based upon EPA statements in an unrelated rulemaking. 
The commenter asserted that despite providing the option for use of PM 
continuous emissions monitoring system (CEMS) as a compliance method 
for PM mass limits in revised NSPS Subparts D and Da, EPA also recently 
suggested it had concerns regarding the accuracy of PM CEMS 
measurements above 0.030 pounds per million British Thermal unit (lb/
mmBtu). As a result, the commenter argued that EPA declined to exempt 
units operating above that level from the NSPS opacity standard even 
when such sources install PM CEMS. 74 FR 5070 (January 28, 2009). 
Commenter requested, to the extent EPA relies on data from PM CEMS 
above 0.030 lb/mmBtu in this proceeding, that the Agency explain how it 
resolved those concerns.
    Response 17. EPA disagrees with the commenter's conclusions 
regarding PM CEMS measurement accuracy above 0.030 lbs/mmBtu. As 
mentioned in the cited Federal Register notice, the contribution of 
filterable PM to opacity at these emission levels (less than 0.030 lb/
mmBtu) is generally negligible, and sources with mass limits at this 
level or less will operate with little or no visible emissions (i.e., 
less than 5 percent opacity). As a result, EPA expects that an opacity 
standard is no longer necessary for such sources because the PM mass 
emission rate standard is substantially tighter, and the use of PM CEMS 
with continuous monitoring of PM emissions is more effective than 
opacity monitoring in these circumstances.
    This comment is also not germane to today's action because the SIP 
revisions at issue did not include the requirement that the affected 
sources install PM CEMS as a precondition to the revision of the 
applicable opacity standard. As noted above, opacity standards serve an 
important role in assuring compliance with PM limits, for example by 
alerting regulators to problems with source operation or control 
measures that would not otherwise be noted except during a stack test 
for PM emissions, which occur only periodically. In some circumstances, 
opacity is the emission standard that is the subject of an enforcement 
case.
    Comment 18. A commenter articulated the position that its 
facilities are operating in compliance with PM limits in the title V 
permits and as a result, the opacity rule is not likely to impact PM 
compliance. The commenter further opined that ADEM should address any 
PM nonattainment issues separately from this rulemaking.
    Response 18. EPA disagrees with the assessment that opacity is 
unlikely to have any effect on PM emissions for all the reasons 
explained in this final action regarding that relationship. Further, 
Alabama's visible emissions rule is a part of Alabama's plan to attain 
and maintain the PM NAAQS. Even though it has been in the SIP for some 
time, the rule was originally included for that purpose. Thus there is 
nothing separate about this action and Alabama's PM nonattainment 
issues--the rule at issue here is part of Alabama's overall plan to 
address the PM NAAQS. Further, if a source is in compliance with the 
opacity and PM limits, then this disapproval action should have little 
effect on that source.

3. Modeling

    Comment 19. Commenters argued that modeling is not required to 
demonstrate that changes to Alabama's opacity rule will not implicate 
the NAAQS. Nonetheless, commenters argued that ADEM performed a 
modeling analysis demonstrating that even earlier versions of the SIP 
revision (predating the Submittals that EPA approved in October 2008) 
would not adversely affect air quality attainment or RFP under very 
conservative assumptions about the relationship between opacity and PM 
emissions. In addition, commenters argued that updated modeling from a 
consultant, ENSR (now known as AECOM), updated ADEM's 2003 modeling in 
2007 using AERMOD (an atmospheric dispersion modeling system and EPA's 
preferred model since 2005) and confirmed ADEM's earlier modeling 
results. Commenters argued that APC and TVA have performed subsequent 
modeling that also

[[Page 18882]]

supported the conclusion that the increased opacity permitted by the 
SIP revisions in the Submittals would not interfere with attainment and 
maintenance of the NAAQS or other requirement of the CAA. Commenters 
asserted that these modeling results show no problem with the NAAQS 
even under unrealistic, worst-case conditions. APC also discussed 
modeling done at APC Plants Barry and Greene and TVA Plant Colbert 
which APC believes supports affirming EPA's 2008 final action approving 
the Alabama SIP revisions. Commenters further noted that ADEM performed 
a modeling analysis demonstrating that the SIP revisions would not 
affect air quality attainment under very conservative assumptions about 
a relationship between opacity and PM emissions. According to the 
commenters, modeling performed by TVA confirms that particulate 
emissions from the Colbert facility would not interfere with 
maintenance of the PM10 or PM2.5 NAAQS, even for 
the unrealistic scenario in which the ESPs are shut down for 10 percent 
of the time every day of the year.
    Response 19. EPA disagrees with the commenter's assertions. As 
discussed in 73 FR 60961 (October 15, 2008), all modeling results are 
predicated on a known or assumed correlation between opacity and PM 
mass emissions. Because this correlation can differ for each source and 
operating condition, modeling that does not use source-specific 
correlations does not and cannot demonstrate with certainty the impact 
of changes in opacity on PM NAAQS. With respect to the modeling 
described by the commenters, the models do not demonstrate that the 
Submittals would not interfere with attainment or maintenance of the 
NAAQS because the models do not appear to have included condensable PM 
or background analyses, to have assessed the impact of nearby PM 
emissions sources, or to have assessed the impact of secondary PM 
formation. Generally, however, the utility of modeling would still be 
limited because the precise relationship between opacity levels and PM 
mass emissions is not known. The docket for this action includes a 
technical support document (TSD) summarizing the modeling that EPA 
received and some of the key assumptions and other issues that impacted 
the utility of the modeling.
    Comment 20. Commenters argued that EPA has routinely approved SIP 
demonstrations based on the use of air models, rightly concluding in 
such matters that the use of the air models leads to a reasonable 
demonstration of compliance with the NAAQS.
    Response 20. As a general matter, EPA agrees that modeling can be a 
useful tool in appropriate circumstances. In this case, the modeling 
provided did not reduce uncertainty regarding the relationship between 
opacity and PM emissions sufficiently to support approval of the 
Submittals. Further, the modeling did not conclusively demonstrate that 
there would be no impact on the NAAQS. Thus, EPA could not conclude 
that the modeling submitted supported approval of the Submittals under 
section 110(l). EPA's modeling TSD provides more information on the 
modeling submitted to EPA as part of this action.
    Comment 21. Commenters stated that monitoring data show a decline 
in ambient PM2.5 and PM10 levels at monitors that 
could potentially be impacted by TVA's Colbert and Widows Creek Plants.
    Response 21. EPA acknowledges that ambient PM levels have been 
improving in many parts of the country as a result of rigorous state 
and EPA efforts to control emissions from many sources of various 
types. EPA wants to maintain these improvements and to support further 
improvements for protection of public health as many areas are still 
designated nonattainment for the NAAQS. Indeed, this is among the 
reasons why reviewing SIP revisions pursuant to section 110(l) is such 
an important exercise.

4. Relative Stringency of Previous Rule (Pre-2008 Final Action) to 
Current Rule (Post 2008 Final Action)

    Comment 22. Commenters argued that Petitioners' claims regarding 
``bundling'' or other potential ways of ``using'' Alabama's visible 
emissions revisions to somehow reduce control efforts while still 
meeting permit requirements are misplaced. According to the commenters, 
it is extremely difficult to achieve continuous or near-continuous 
compliance with the opacity rules, so there is absolutely no incentive 
to try to ``game'' the system by trying to achieve less than maximum 
opacity control at any one time. Further, commenters argued that 
facility procedures aimed at minimizing opacity levels at all times in 
order to avoid non-exempted exceedances insofar as practicable remain 
intact after the rule revisions went into effect January 1, 2009.
    Response 22. The commenters' argument appears to be that even 
though ``bundling'' could occur, it will not, because sources are 
diligently striving to minimize their opacity levels. While EPA 
certainly expects that sources are seeking to minimize their opacity 
levels, EPA's analysis of the revision considered what the two versions 
of the Alabama rules allowed--and not necessarily how sources were 
operating under each rule scenario. As with the modeling submitted by 
many commenters, the primary problem associated with their conclusions 
about the amount of PM emissions during longer periods of elevated 
opacity is the reliance on an assumed relationship between opacity and 
PM emissions that has not been established for the specific source. As 
mentioned previously, this relationship is unknown for each source and 
operating condition, absent sufficient evaluation. EPA disagrees that 
the ``bundling'' of periods of high opacity could never reflect higher 
PM mass emissions.
    EPA understands the difficulties associated with operating older 
facilities, but disagrees that continuous compliance with opacity rules 
can be achieved only through extreme difficulty. The Alabama SIP 
opacity limits in effect following this disapproval should generally be 
capable of being met by a source that is properly maintained, operated 
and controlled. There are control technologies and operational 
paradigms that allow older facilities to comply with Alabama's pre-
October 15, 2008, opacity rules (this was recognized by the court in 
the TVA Colbert case, Sierra Club v. TVA, 592 F. Supp. 2d 1357 (N.D. 
Ala. 2009)).
    Comment 23. Commenter explained that to attempt to bundle six-
minute opacity exceedances would necessitate a purposeful ``turn-down'' 
of the unit's ESP and, thus, result in non-compliance with two 
provisions of the commenter's Lowman Plant's major source operating 
permit (title V permit): (1) That ``all air pollution control devices * 
* * be * * * operated at all times in a manner so as to minimize the 
emissions of air contaminants,'' and (2) once the emissions exceed a 
six-minute average opacity of 20 percent, corrective actions must be 
taken within two hours.
    Response 23. EPA's analysis of the SIP revisions at issue is 
governed by, among other provisions, section 110(l) of the CAA. In that 
context, as was explained previously, EPA must compare the existing SIP 
and the proposed SIP revision. While affected sources may have permit 
limits that are more stringent than the applicable SIP regulations, 
EPA's analysis must focus on what the SIP itself would allow. Permits 
may be revised from time to time, depending on applicable requirements. 
As a result, the type of analysis completed by the commenter based on 
the applicable permits might

[[Page 18883]]

be changed over time. Further, while EPA would, of course, be concerned 
by a purposeful ``turn-down'' of any control device, EPA expects that 
there are other circumstances under which extended periods of 
consecutive exemptions would allow high opacity levels (and mass 
emissions) that would not occur in a well-operated, well-controlled, 
and well-maintained plant. EPA appreciates PowerSouth Energy 
Cooperative's (PSEC's) analysis, which demonstrates that this 
disapproval action should have little effect on the vast majority of 
sources.
    Comment 24. Commenters provided data in three attachments provided 
by PSEC showing emissions during the period of January 1, 2009, thru 
September 30, 2009, clearly indicate that no ``bundling'' occurred. For 
example, Attachment 1 shows that of the total of 90 six-minute periods 
of excess opacity (i.e., six-minute averages of opacity greater than 20 
percent), including startup/shutdown and load change periods, there 
were 40 occurrences of isolated six-minute periods of excess opacity; 
14 occurrences of two consecutive six-minute periods of excess opacity; 
four occurrences of three consecutive six-minute periods of excess 
opacity; one occurrence of four consecutive six-minute periods of 
excess opacity; and one occurrence of six consecutive six-minute 
periods of excess opacity.
    Response 24. EPA appreciates the submission of operating data. One 
of the difficulties with the technical analysis regarding opacity is 
that details regarding facility operation can impact both opacity and 
PM in different ways. Further, EPA must consider the effect of the 
Submittals on how a facility may be allowed to operate, not just how 
the facility actually has been operating. With these considerations in 
mind, the operating data were informative, but not determinative, 
because even if a facility currently operates as the commenters 
describe, the facility would be allowed to operate otherwise under 
Alabama's proposed SIP revisions.
    Comment 25. Commenters suggested that this 22 percent limit ensures 
that the average daily opacity under the revised SIP is no greater than 
under the previous SIP. The commenters asserted that this fully 
responds to AEC's hypothesis of the ``bundling of high opacity 
periods'' and concerns about the elimination of the ``40 percent cap'' 
under the revised SIP. Further the commenters explained the use of a 
daily opacity limit to establish short-term equivalency is appropriate 
because a calendar day is the shortest period over which compliance 
with the PM NAAQS is measured. The commenters stated that AEC provides 
no supporting data on the bundling and operating data provided, which 
commenters believe demonstrates that bundling has not occurred.
    Response 25. The Commenters' statements are incomplete. While the 
22 percent limit does serve the purpose of ensuring subject sources are 
constrained by the same maximum allowable average daily opacity as 
under the previously approved SIP (as explained in EPA's 2008 final 
notice), these SIP revisions would allow opacity levels of up to 100 
percent during exempt periods and for multiple consecutive exempt 
periods, neither of which was previously authorized under the SIP. The 
prior version of the visible emissions rule capped maximum opacity at 
40 percent and limited the time at such level to only six minutes per 
hour. Further, whether ``bundling'' in fact has occurred in the past is 
not the focus of EPA's analysis for purposes of section 110(l).\20\ As 
part of this reconsideration, EPA has had to re-evaluate the concept of 
the ``22 percent daily cap'' supported by the commenter. EPA has 
concluded that even with an ``average daily opacity'' cap, these SIP 
revisions undermine the purpose and effectiveness of the opacity 
standard by allowing extended periods of high opacity. Such high 
opacity can be indicative of problems with control device operation or 
other circumstances potentially leading to increased mass emissions. 
Given that some sources affected by the opacity limits at issue in the 
SIP revisions are located within designated nonattainment areas, EPA 
concludes that this likelihood of increased emissions renders the 
Submittals unapprovable under section 110(l).
---------------------------------------------------------------------------

    \20\ The SIP revisions at issue have been under reconsideration 
since before the changes to Alabama's visible emissions rule now 
being disapproved went into effect; thus, the data submitted in 
public comments may not be a representative random sampling of the 
long-term effects of the rule.
---------------------------------------------------------------------------

    Comment 26. Commenters argued that the equivalency between the 
previous and revised SIPs, with respect to the short-term and long-term 
emission rates, will ensure that there will be no interference with 
NAAQS notwithstanding the bundling of high opacity periods. Further, 
the commenters mentioned that in approving the North Carolina SIP 
revision for visible emissions, EPA concluded that such bundling 
through the ``elimination of the current restriction of no more than 
one six minute exception period per hour'' does not ``pose a problem 
for purposes of Section 110(l).'' Commenters cite to 70 FR at 61558 for 
support.
    Response 26. As EPA explained earlier in this final action, the 
North Carolina opacity revisions are not analogous to Alabama's opacity 
revisions for the main reason that Alabama's revisions allow for 
periods of opacity up to 100 percent, whereas the North Carolina 
revision retained the same maximum opacity of 40 percent. The allowance 
for this high opacity level, along with the lengthy time allowed for 
elevated opacity (up to 2.4 consecutive hours), was not present in the 
North Carolina case.
    Comment 27. Commenters argued that plant operating data confirm 
that the bundling of high opacity periods does not occur in practice. 
Further, the 22 percent cap resolves any concerns regarding the 
bundling were it to occur.
    Response 27. EPA appreciates commenters' information on actual 
operations; however, as explained previously EPA's analysis under 
section 110(l) focuses on what the revised SIP rules would allow. 
Further, as discussed above, the 22 percent cap does not resolve EPA's 
concerns about extended periods of very high opacity.
    Comment 28. Commenters argued that the rule really has nothing to 
do with air quality, and that if it did, EPA would have to justify and 
explain why it is proposing to condemn an opacity rule that is 
numerically more stringent and that has fewer exemptions than many 
other states' opacity rules.
    Response 28. EPA does not agree with commenters' statements. 
Alabama's visible emissions rule is part of Alabama's EPA-approved SIP, 
and part of its plan to attain and maintain the PM NAAQS. As a result, 
any revision of the EPA-approved opacity rules is subject to evaluation 
under section 110(l) of the CAA. Furthermore, the extended consecutive 
periods of opacity exemptions allowed renders this standard uniquely 
less stringent than any other EPA-approved opacity rule.
    Comment 29. Commenters argued that the daily opacity limit is 
neither necessary for approval nor unlawful. According to the 
commenters, because EPA's proposed approval was not based on a finding 
that the rule would not allow any more PM during a 24-hour period than 
the old rule, it is not necessary for the daily limit to meet such a 
criterion.
    Response 29. EPA disagrees that the potential for more PM emissions 
as a result of elevated opacity is not germane to this action. EPA's 
prior approval of the SIP revisions was based on uncertainty about 
whether the revisions

[[Page 18884]]

to the opacity standard would allow more PM emissions during a 24-hour 
period. EPA would not have previously proposed approval if the record 
clearly demonstrated that the rule would have resulted in increased PM 
in nonattainment areas. After reviewing public comment and the State's 
revised submissions, EPA based its prior approval in part on the 
average daily opacity limit included in the revision. At that time, EPA 
accepted certain assumptions, including that the 22 percent daily 
opacity limit would serve to lessen the potential for elevated 
emissions of PM associated with the increases in opacity. Following 
EPA's reconsideration and review of information submitted to EPA, EPA 
no longer accepts that the average daily opacity limit is an 
appropriate or effective tool for evaluating the impact of the 
Submittals on PM emissions. Given EPA's position that there is a 
sufficient likelihood of increased PM emissions associated with the 
elevated opacity allowed under the SIP revisions, the Submittals are 
not approvable under 110(l).

5. Attainment and Maintenance of the PM NAAQS (PM10 and 
PM2.5) and Data Submitted in Response to October 2009 
Reconsideration Proposal

    Comment 30. Commenter argued that while the Clean Air Fine Particle 
Implementation Rule requires that direct PM2.5 emissions be 
addressed in PM2.5 attainment demonstration SIPs, the 
primary thrust of the regulation is the control of precursor compounds 
and not direct PM2.5 emissions. According to the commenters, 
if the Alabama attainment plans are similar to those of Tennessee in 
that sulfates are identified as the main contributor to fine 
particulate matter and reliance is being placed on reductions of sulfur 
dioxide (SO2) to demonstrate compliance, with no measure 
specified for stationary direct PM2.5, then the Petitioners' 
assertion that approval of the Alabama SIP revisions would adversely 
affect PM2.5 attainment or RFP has no merit and should be 
rejected. The commenters explained that if this is the case then the 
Petitioner's assertion that approval of the Alabama SIP revisions would 
not be consistent with sections 110(l) and 193 of the CAA should also 
be rejected as having no merit unless it can be demonstrated that a 
fixed source of direct PM2.5 is a significant contributor to 
a nonattainment area. Additionally, according to the commenters, this 
should be an adequate affirmative demonstration that the requirements 
of sections 110(l) and 193 of the Act are not an issue. Further, the 
commenters asserted that even for areas achieving conformance with the 
PM2.5 ambient standard, for which no SIP would be required, 
the effect of the reductions of PM2.5 precursors would be so 
dominant as to negate any changes to direct PM2.5 emissions.
    Response 30. As was explained earlier, given that ADEM did not 
submit a full attainment demonstration specifically addressing this 
rule and did not propose any offsetting reductions to compensate for 
emission increases in nonattainment areas, EPA's analysis is 
necessarily focused on the comparison between the previous EPA-approved 
version of the visible emissions rules and the revisions that the State 
seeks, in order to ensure that the revision would not allow an increase 
in emissions of pollutants that would interfere with attainment or 
maintenance of the NAAQS, or with other requirements of the CAA. A 
primary consideration, therefore, is whether the revisions could result 
in increases in emissions of a type for which the area where the source 
is located is designated nonattainment. In this context, EPA must 
evaluate the relative stringencies of the two versions of the opacity 
rules, as was explained earlier.
    EPA notes that the commenter's arguments here are premised upon 
what might or might not be appropriate in the context of a 
nonattainment SIP for certain pollutants in an area. EPA does not agree 
that the implementation regulations for the 1997 PM2.5 NAAQS 
are designed or intended to ignore direct PM2.5 emissions 
from sources, and evaluation of controls for such emissions is a 
required element of such a SIP. While it may be correct that a 
nonattainment SIP in a particular area might be designed to focus upon 
emissions of SO2 and nitrogen oxides, or other 
PM2.5 precursors, as an attainment strategy, it does not 
follow that emissions of PM2.5 from the sources subject to 
Alabama opacity rule do not impact attainment and maintenance of these 
NAAQS. Considerations mentioned by the commenters might be relevant in 
the evaluation of the attainment demonstration accompanying a 
nonattainment SIP for the 1997 PM2.5 NAAQS, but they are not 
relevant in the context of a section 110(l) analysis.
    Comment 31. Commenters argued that Alabama's revised SIP for 
visible emissions is a small piece in the overall PM attainment puzzle. 
According to the commenter, any incremental primary PM2.5 
emissions increase as a result of revising the SIP, assuming for 
purposes of argument that such an increase occurs, would be an 
inconsequential contributor to the PM2.5 attainment status 
against the background of the significantly greater secondary 
PM2.5 (sulfate and nitrate) contributions. The commenter 
asserted that viewed in this broader context, EPA could reasonably 
conclude, based on the equivalency demonstration, that the revised SIP 
is consistent with the earlier SIP.
    Response 31. The comment fails to appreciate EPA's limitations in 
reviewing SIP revisions, as described in section 110(l). In addition, 
EPA did not receive an ``equivalency demonstration'' from ADEM that 
addressed all the elements in section 110(l). Further, an increase of 
PM emissions by any increment would make it more difficult for areas in 
Alabama to attain and maintain the NAAQS. EPA has considered the SIP as 
a whole, and concludes that the potential increase renders the 
revisions not approvable.
    Comment 32. Commenters explained that following new data collected 
under the current SIP confirms that EPA's prior analysis was sound:
    A. New data collected under the current SIP shows there is no 
``bundling;''
    B. New data collected under the current SIP shows that daily 
opacity has improved; and
    C. New data collected under the current SIP shows why the rule 
makes sense.
    Response 32. EPA appreciates the submission of these data. EPA 
disagrees, however, with the conclusions that the commenters draw from 
the data. The commenters' focus on what is actually happening with 
respect to ``bundling'' and opacity levels fails to consider what could 
happen under the SIP revision. EPA's analysis pursuant to section 
110(l) must focus on the differences between the two versions of the 
visible emissions rules in terms of what they would allow and not on 
the choices individual facilities may have made to date in terms of 
opacity and PM emissions. Thus, EPA does not agree that the data 
presented by commenters support approval of the Submittals. The 
commenters did not, unfortunately, submit data to establish what the PM 
mass emissions were during periods of elevated opacity at these 
sources.
    Comment 33. Commenter saw no basis for the supposition that 
Alabama's opacity rule revisions will affect PM NAAQS compliance. The 
commenters asserted that as indicated in the attachments, PSEC's Lowman 
Unit 1's opacity compliance continues to be very good. Additionally, 
the commenters explained that annual particulate emission testing in 
2008 and 2009 indicate PM emissions well below the

[[Page 18885]]

standard and show no difference before and after the opacity rule 
revisions.
    Response 33. EPA acknowledges that some facilities affected by the 
SIP revisions may be operating at opacity levels below those required 
by the Alabama SIP. Indeed, a source that is well-controlled, well-
maintained, and well-operated could achieve opacity levels well below 
20 percent. However, EPA's obligation under section 110(l) is to 
consider how a facility could operate under the new rule--not how it 
typically operates or has historically operated. Moreover, EPA notes 
that annual PM testing offers valuable but limited information about 
mass emissions because the testing occurs only once per year for a 
limited period of time. The question not addressed by the comments is 
what the PM mass emissions would be, were a source to be operating at 
the 100 percent opacity for 2.4 hours contemplated by the SIP revision 
at issue.
    Comment 34. Commenters asserted that there are no new data that 
would support EPA's withdrawal of its approval of the rule.
    Response 34. As was discussed previously, EPA's authority to 
reconsider a SIP revision is not limited only to circumstances where 
there are new data. EPA has already explained in today's action why its 
prior approval was not consistent with the purposes of section 110(l), 
and that reconsideration and disapproval is appropriate. Notably, the 
reconsideration was initiated before the revised rule went into effect 
and that sources should be capable of complying with either rule or 
both rules simultaneously.
    In addition, EPA disagrees that no new information supports this 
disapproval. A number of commenters have submitted data and information 
that, while not directly addressing the questions that EPA posed, 
nevertheless help to illustrate the problems with the SIP revisions. 
For example, information submitted by AEC suggests that at least some 
sources, under some conditions, could have increased PM emissions 
during the longer periods of higher opacity that would be permissible 
under the revised visible emissions rules in the Submittals. See 
Comment Letter from George E. Hays and attachments (on behalf of 
Alabama Environmental Council, among others), Docket No. EPA-R04-OAR-
2005-AL-0002-0089.1. Moreover, many of the commenters during the 
reconsideration process submitted comments in which their analysis 
suggested that there is a relationship between PM mass emissions and 
opacity, even if the precise correlation cannot be established without 
much more rigorous testing and evaluations on a source specific basis. 
See Modeling TSD. As was noted earlier, even some of the commenters 
opposing EPA's disapproval action identified the uncertainty in the 
relationship between opacity and PM mass emissions, and the possibility 
of the SIP revisions resulting in emission increases. See, e.g., 
Comment Letter from Lauren E. Freeman (on behalf of the Utility Air 
Regulatory Group) at 4, Docket No. EPA-R04-OAR-2005-AL-0002-0086.1.
    Comment 35. Commenter noted that with regard to EPA's request for 
information on condensable PM, COMS do not measure condensable PM, 
which is in a gaseous form at stack conditions.
    Response 35. EPA acknowledges the response, which underscores one 
component of the uncertainty inherent in the relationship between 
opacity and PM emissions.

6. Impact of Uncertainty in These SIP Revisions

    Comment 36. Commenters asserted that while EPA has consistently 
(and correctly) noted the uncertain relationship between opacity and PM 
for short-term analysis, any question regarding how this uncertainty 
might impact PM, in this case, has now been eliminated entirely with 
the addition of the 22 percent daily average requirement. Commenters 
further stated that ADEM's August 2008 submittal remedied any 
``uncertainty'' question with respect to 24-hour PM by including an 
additional restriction on daily average opacity, so that the average 
daily opacity allowed under the revision is now no greater than under 
the previous SIP.
    Response 36. EPA has shown through calculations, that the maximum 
allowable average daily opacity under both the previous rule and the 
revised rule is 22 percent. However, as discussed above, the revised 
visible emissions rule at issue in the SIP revisions would allow 
sources to operate in a manner they could not under the previous rule--
including increases in opacity concentrations up to 100 percent for an 
extended period of time. As a result, under the revised rule, sources 
may now be permitted to cause much more opacity to levels that would 
have been a violation under the previous EPA-approved SIP rules. Such 
emissions include very high concentrations of excess opacity for 
extended periods. EPA has thus concluded that the ``average daily 
opacity'' cap provides no assurance against increased mass emissions. 
Indeed, as discussed above, EPA has concluded that there is a 
sufficient likelihood of increased mass emissions under the revisions 
so as to make it unapprovable under section 110(l).
    Comment 37. Commenters stated that there is always some uncertainty 
when attainment or interference with a NAAQS is considered in a SIP 
process because it involves an element of prediction and reliance on 
modeling. Further, commenters explain their positions that section 
110(l) does not require absolute certainty and EPA should not 
substitute ``could'' for ``would'' in the 110(l) context.
    Response 37. EPA agrees the Act does not require attainment 
demonstrations or other technical analysis of impacts on attainment or 
maintenance of the NAAQS to an ``absolute certainty.'' However, to make 
a determination that the NAAQS will not be adversely impacted, EPA must 
at least be able to reach the conclusion that this is most likely the 
case. In this action, EPA is relying on what is known about the 
relationship between opacity and PM emissions to conclude that the 
State's revised visible emissions rules in the Submittals is less 
stringent than the previous EPA-approved rule, and that the likely 
increases in emissions of PM at affected sources would be inconsistent 
with section 110(l). Under the revised rule, a source could exceed its 
20 percent opacity limit for well over an hour (up to 100 percent 
opacity). In contrast, the previous SIP-approved rule allowed only one 
occurrence per hour of a 6-minute average opacity above 20 percent (and 
only up to 40 percent). Control equipment that is effective enough to 
avoid a second occurrence of 6-minute average opacity above 20 percent 
will make even the first occurrence an infrequent event. Likewise, 
control equipment and operating procedures that are effective enough to 
enable a unit to meet the requirements of the previous SIP will also 
allow a lesser quantity of PM emissions than control equipment and 
operating procedures that are sufficient to comply with the current SIP 
revision but do not necessarily enable a unit to comply with the 
previous SIP rule.
    In addition, contrary to the commenters' belief, this is not 
dependent upon replacing the word ``would'' with the word ``could.'' 
EPA's conclusion is that available evidence indicates that some of the 
affected sources would have increases in PM emissions, and that these 
emissions would occur in locations where such increased emissions would 
interfere with attainment and maintenance of the NAAQS. Commenters 
evidently misconstrue ``uncertainty'' about the

[[Page 18886]]

precise amount of such likely emissions increases as evidence that no 
such increases could occur.
    Comment 38. Commenters raised concerns regarding PM CEMS 
technology, and the representativeness of PM emissions data obtained 
during Performance Specification (PS) 11 testing. See 40 CFR part 60, 
Appx. B. Briefly, the commenters asserted that PS 11 correlation 
testing, which requires disabling of PM control devices under 
artificial conditions in order to obtain sufficient variability in PM 
emissions to satisfy the PS 11 statistical criteria, rarely provide 
data representative of actual operations or control device 
malfunctions. Commenters also noted that it would not make sense to 
require sources to spend money to install PM CEMS or to perform 
periodic performance tests in order to develop a source-specific 
correlation between opacity and PM.
    Response 38. EPA disagrees with the commenter's views regarding PM 
CEMS technology and PS 11 testing, especially in the context of 
evaluating the SIP revisions at issue here. The procedures of PS 11 are 
conducted to develop a source-specific PM emissions correlation for an 
individual source operating over a range of PM emissions conditions 
through comparison of results from PM emissions testing and PM CEMS. 
Note that PS-11 does not require PM control devices to be disabled. 
Those PM measurement and testing correlation procedures differ from an 
opacity and PM emissions correlation, which is the fundamental issue 
requiring resolution for addressing the visible emissions rules 
revision in Alabama's Submittals. EPA also disagrees that use of PM 
CEMS or periodic performance testing could be ``nonsensical'' in 
determining a source-specific correlation between opacity and PM 
emissions. Indeed, as EPA has previously explained, source-specific 
approaches such as concurrent opacity and PM emissions measurements may 
be one way to determine ``* * * any useful and definitive relationships 
between stack particulate mass emissions values and their corresponding 
opacity levels * * *'' 73 FR 60962 (October 15, 2008).
    EPA agrees that data obtained over a range of operating and control 
device conditions would be necessary to develop a site-specific 
correlation between opacity and PM emissions and that a single, site-
specific correlation should not be extrapolated to other sources. 
Retaining Alabama's original visible emissions rule (the pre-October 
15, 2008, final rule) relieves ADEM (and affected sources) from 
performing an assessment of increased source opacity on PM emissions.
    Comment 39. Commenters suggested that the source-specific nature of 
the opacity/PM relationship does not mean that the uncertain impact of 
a particular change in an opacity rule can be resolved by requiring 
source-specific testing.
    Response 39. EPA agrees that a well-designed data collection 
program should be able to reduce to acceptable levels, if not 
eliminate, most of the uncertainty associated with the relationship 
between PM emissions and opacity resulting from changing opacity 
limits. However, as the commenters themselves argue, the variability in 
the relationship between PM emissions and opacity limits is such that, 
absent the use of PM CEMS, source specific evaluation would be one way 
to determine the impacts of the change at a given source. EPA through 
this disapproval is not determining that the only means to revise an 
opacity standard is through source by source evaluation, nor is EPA 
requiring that with today's action.
    Comment 40. Commenters argued that to the extent that EPA seeks 
information on PM compliance methods in order to assess the costs of 
requiring Alabama to impose more source-specific PM testing in order to 
evaluate the impact of its revised opacity rule, commenters disagree 
that such an evaluation is required under CAA 110(l).
    Response 40. EPA agrees that an assessment of the cost of a 
potential requirement for source-specific testing is not necessary 
pursuant to section 110(l). In order to fully provide the public with 
an opportunity to comment on the proposed action, EPA sought specific 
information, including costs, to assist the public in identifying what 
information might be useful to EPA. EPA has already explained how it 
considered the SIP revisions and the basis for its final action.

7. Applicability of CAA Sections 110(l) and 193 to This Action

    Comment 41. Commenters stated that because EPA correctly found the 
revisions would not interfere with the attainment or maintenance of the 
NAAQS or any other requirement of the CAA, section 110(l) concerns are 
not implicated. The commenters stated that as long as a SIP revision 
does not ``interfere with'' air quality (i.e., make it worse), EPA must 
approve it. According to the commenter, Alabama's rule is consistent 
with the development of an overall plan for attainment, in that all of 
the sources subject to the Rule are also subject to various other 
programs and requirements that EPA has approved to ensure the NAAQS are 
protected.
    Response 41. Commenters' focus on ``air quality'' is a good point--
and was EPA's primary concern as well. EPA's action in this case 
focuses on the known differences between the previous EPA-approved SIP 
rules and the SIP revisions in the Submittals, and what is known 
regarding the technical aspects of the relationship between opacity and 
PM mass emissions. Specifically, that the revised rule allows extended 
periods of much higher opacity that were not previously authorized. EPA 
has concluded that available evidence indicates that the revised rule 
could result in more emissions, and thus interfere with attainment and 
maintenance of the NAAQS, to use the commenters' term, ``make it 
worse.'' Further, for older facilities (such as the ones subject to the 
visible emissions rule at issue), particularly those that are less 
controlled, opacity can be an important indicator of operation and 
control device performance, which, in turn, can affect air quality. In 
this context, and lacking reliable scientific correlations between 
opacity emissions and PM NAAQS violations, EPA has concluded that the 
rule changes described in the Submittals are not approvable under 
section 110(l).
    With respect to the commenters' argument that other regulatory 
programs exist to help insure attainment and maintenance of the NAAQS, 
EPA agrees. However, for the sources affected by the visible emissions 
rules at issue, the opacity standards provide an important tool to 
assure compliance with these other measures. The mere existence of a 
regulatory framework to provide for the attainment of the NAAQS does 
not negate the need for effective tools to assure that the framework 
succeeds.
    Comment 42. Commenters stated that unless ADEM relied upon the 
opacity standard to comply with the PM NAAQS, section 110(l) 
considerations do not come into play. The commenters further stated 
that in this case, Alabama did not rely on the opacity standard to 
demonstrate attainment of the PM NAAQS.
    Response 42. Alabama's visible emissions rule is part of Alabama's 
plan to attain and maintain the NAAQS, and it is in the EPA-approved 
SIP (and has been for a long time). Any revision to the SIP is subject, 
by the plain text of the CAA, to the requirements of section 110(l).
    Comment 43. Commenters stated that EPA's October 2008 approval 
applied and satisfied the correct CAA section 110(l) standard. 
According to the

[[Page 18887]]

commenters, EPA is not required to re-examine the adequacy of the level 
of reductions provided in a plan that has already achieved attainment, 
or speculate how a requested SIP revision might fit into the mix of 
controls that may be chosen by the state to support a future attainment 
demonstration with respect to a new standard. The commenters argued 
that EPA's review under CAA section 110(l) only needs to address 
whether the revision would affect the status quo. EPA could have (and 
in commenters' view, should have) limited its review to whether the 
revision interfered with the requirement to assess good O & M of PM 
control equipment between PM stack tests. Further the commenters 
asserted that because Alabama did not rely on a short-term opacity/PM 
relationship to support its previously approved PM attainment 
demonstration, EPA was not required to analyze changes in the opacity 
standard for equivalency under section 110(l).
    Response 43. EPA does not agree with commenters' characterization 
of EPA's obligation under section 110(l). As a point of clarification, 
Alabama has several nonattainment areas, including PM2.5 
nonattainment areas. The State's visible emissions rule applies to a 
group of stationary sources Statewide--it does not apply only in 
designated attainment areas. Thus, EPA does not agree with commenters' 
argument that because Alabama is currently attaining some NAAQS, EPA's 
consideration under section 110(l) should be different. Further, as was 
noted earlier, in the absence of an attainment demonstration regarding 
the rules at issue, EPA can approve a SIP revision for a nonattainment 
area only if EPA finds that it will not worsen air quality by 
increasing emissions of a nonattainment pollutant, and it is otherwise 
consistent with attainment and maintenance of the NAAQS. Even accepting 
the commenters' argument that the opacity standard is intended to be a 
gauge of good O & M of a source, the SIP revisions contemplated in the 
Submittals raise concerns because the revisions allow facilities to 
emit up to 100 percent opacity for extended periods of time--which is 
hard to square with the need to assure good source operation. Indeed, 
other commenters have asserted that opacity at such levels is the 
equivalent to turning off any relevant control device for an extended 
period of time. Even under what EPA understands commenters' argument to 
be, the SIP revisions present serious concerns about good O & M and 
would not be approvable.
    Comment 44. Commenters explained their view that 110(l) does not 
impose on states a requirement to ``demonstrate'' that each proposed 
revision will not interfere with attainment or require EPA to reject 
each revision that presents ``some remote possibility for 
interference.'' Commenters cited to Kentucky Resources Council (KRC), 
Inc. v. EPA, 467 F.3d 986, 994-95 (6th Cir. 2006) for support.
    Response 44. Section 110(l) prohibits any SIP revision that would 
have the effect of interfering with attainment or maintenance of the 
NAAQS, RFP, or any other requirements of the CAA. Typically, states 
elect to provide the requisite information necessary to establish that 
their intended SIP revisions would not have any of these effects. EPA 
often works with states to evaluate the effects of a given SIP 
revision. In the final analysis, however, EPA is not authorized to 
approve any SIP revision that has such effects.
    When, as here, available information indicates that the SIP 
revision at issue could result in the increase in PM emissions at some 
sources located in or near designated PM nonattainment areas, EPA has 
concluded that the SIP revision is not approvable and that residual 
uncertainty about the precise amount of additional PM emissions that 
would be associated with the dramatic increases in opacity does not 
render the revision approvable.
    Commenters' citation to KRC, 467 F.3d 986, is misplaced because the 
case supports EPA's disapproval action. In that case, the Sixth Circuit 
considered an EPA action approving revisions to the Kentucky SIP 
regarding Kentucky's inspection and maintenance (I/M) program that 
removed the requirement from the active portion of Kentucky's SIP. The 
Court explained that Congress did not intend for EPA to ``reject each 
and every SIP revision that presents some remote possibility for 
interference. Thus, where the EPA does not find that a SIP revision 
would interfere with attainment, approval of the revision does not do 
violence to the statute.'' KRC at 994. The Court upheld EPA's view 
that:

    As long as actual emissions in the air are not increased, EPA 
believes that equivalent (or greater) emissions reductions will be 
acceptable to demonstrate non-interference. EPA does not believe 
that areas must wait to produce a complete attainment demonstration 
to make any revisions to the SIP, provided the status quo air 
quality is preserved.

KRC at 995 (quoting a prior SIP action, 70 FR 28,429, 28,430 (May 18, 
2005)). During the course of the SIP revision at issue in that case, 
EPA informed Kentucky of the need to demonstrate equivalent offsetting 
reductions due to the existing nonattainment areas in Kentucky. 
Kentucky responded by adopting additional control requirements into its 
SIP programs which were sufficient to offset the increased emissions 
anticipated as a result of removing the I/M program from the active 
SIP. This type of equivalency analysis was not provided by Alabama and 
we cannot conclude in this case that the status quo air quality will be 
maintained. Rather, in the case of Alabama, EPA judges that there is 
more than a remote possibility for increased emissions under the SIP 
revision and that our current action is consistent with the KRC case.
    Comment 45. Commenters make a distinction between attainment and 
nonattainment areas for purposes of a 110(l) analysis. Commenters 
appear to suggest that because Alabama had no outstanding nonattainment 
plans due in the time frame of the October 15, 2008, final rule, that 
the 110(l) analysis should address whether the revision would affect 
the status quo.
    Response 45. EPA agrees that the 110(l) analysis for a 
nonattainment area should, in the absence of an attainment 
demonstration, assure at least that the status quo is maintained. Thus, 
EPA will generally not approve a SIP revision that allows additional 
emissions of pollutants for which an area is designated nonattainment 
in the absence of offsetting reductions. Because EPA now concludes that 
Alabama's SIP revisions are likely to result in an increase in PM 
emissions, for which parts of Alabama are designated nonattainment, it 
cannot be approved consistent with section 110(l).\21\ While EPA has 
previously required a more robust 110(l) analysis for nonattainment 
areas, there is still an analysis required for attainment areas. 
Section 110(l) applies to all SIP revisions, regardless of whether the 
revision is impacting attainment areas or nonattainment areas. 
Alabama's visible emissions rule at issue is part of Alabama's plan to 
attain and maintain the NAAQS. The analysis under 110(l) does not 
depend on what SIP revisions are currently due, although 110(l)

[[Page 18888]]

requires EPA to consider other applicable requirements in the SIP.
---------------------------------------------------------------------------

    \21\ As was discussed above, EPA also concludes that even if the 
uncertainty about the impact of the SIP revision on PM emissions 
were so great that EPA could make no technical judgment at all about 
the net effect of this SIP revision on PM emissions, the revision 
would still not be approvable under section 110(l).
---------------------------------------------------------------------------

    Comment 46. Commenters explained that because they believe that 
there is no relationship between opacity and PM, the inquiry as to 
110(l) could end there. Commenters also argued against substituting the 
words ``could interfere'' for ``would interfere'' in 110(l).
    Response 46. EPA does not agree that there is no relationship 
between opacity and PM emissions. Rather, EPA concludes that there is a 
general relationship between opacity and PM emissions, but for a 
specific source and its operating characteristics, there is uncertainty 
about whether increases in opacity are accompanied by increases in PM 
emissions without examination of each source at issue. In addition, EPA 
does not substitute the words ``could interfere'' for ``would 
interfere'' in interpreting and applying 110(l). For any given source 
at any given time, it is accurate to say that increased opacity could 
be accompanied by increased PM emissions. However, in evaluating what 
would be allowed under the Submittals across all sources and 
circumstances, EPA concludes it is likely that the increased opacity 
allowed by the Submittals would result in increased PM emissions. EPA 
judges the significant increase in the flexibility in the opacity 
exemptions allowed to sources under the revised rule is great enough 
that, absent a convincing demonstration otherwise, the Agency may only 
conclude the revised rule hinders (i.e., ``would interfere'' with) 
efforts to attain and maintain compliance with the PM NAAQS.
    Comment 47. Commenters explained that changes to Alabama's Visible 
Emission Rule do not affect compliance with PM limits. According to the 
commenter, Alabama has not relied on opacity limits to demonstrate 
attainment with the PM NAAQS. Thus, the commenter argued that section 
110(l) does not apply here at all.
    Response 47. Section 110(l) applies, by its plain text, to all SIP 
revisions including Alabama's 2003 and 2008 Submittals. Contrary to the 
commenter's belief, the State has historically included the visible 
emissions rules in its SIP for purposes of attainment and maintenance 
of the PM NAAQS. The fact that the State may not have sought specific 
SIP credit attributable to the opacity limits (not to be confused with 
SIP credit for the PM limits that such opacity limits are designed to 
assure compliance with) does not mean that the opacity limits are not 
part of the SIP.
    Comment 48. Commenters explained that 110(l) does not require 
absolute certainty regarding interference with attainment and 
maintenance of the NAAQS. According to the commenters, EPA has never 
taken that position and it would be a departure from Agency practice to 
take such a position. Commenters cited to KRC v. EPA, 467 F.3d 986 (6th 
Cir. 2006) and Galveston-Houston Ass'n for Smog Prevention (GHASP) v. 
EPA, 289 Fed. Appx. 745 (5th Cir. 2008). Commenters concluded that EPA 
cannot rely on mere uncertainty as a basis for disapproving a SIP 
revision.
    Response 48. EPA agrees that section 110(l) does not require 
absolute certainty. EPA's decision today relies on certainties 
concerning the impacts of the revisions to Alabama's visible emissions 
rules in the Submittals. These certainties include that the Alabama 
rule would allow for increase of maximum opacity from 40 percent to 100 
percent and would allow such increases for up to 2.4 hours at a time, 
instead of for only six minutes per hour. EPA is disapproving the 
revision because while there are uncertainties--such as precisely when 
PM mass emissions would increase or by what precise amount--EPA expects 
that it is likely in at least some circumstances to result in increases 
in PM mass emissions. EPA generally, absent an attainment demonstration 
or offsetting emission reductions, will not approve a SIP revision that 
results in increases in emissions of a pollutant for which an area is 
designated nonattainment pursuant to the requirements of section 
110(l). EPA has already discussed the KRC case in a previous response. 
The GHASP case supports EPA's position in this action because that was 
another case where the court upheld EPA's interpretation that section 
110(l) requires that a SIP revision must at least maintain status quo 
air quality to be approvable.

8. CAA Section 110(l) ``Demonstration'' of Non-Interference With the 
NAAQS and Other Requirements

    Comment 49. Commenters argued that it is not clear what EPA means 
when it says that ``Alabama has not provided EPA with an affirmative 
demonstration that the [Rule] will not interfere with the attainment 
and maintenance of the NAAQS'' (74 Fed. Reg. at 50933), since, in the 
commenters' view, that is exactly what the 2008 revision adding the 22 
percent daily average cap ensures. Commenters further stated that to 
require Alabama to provide more than the modeling of its 2003 submittal 
would be contrary to what the CAA requires and would be essentially 
asking for the impossible given the acknowledged uncertainty between 
opacity and PM, particularly for short-term analysis.
    Response 49. EPA does not agree with the commenters' interpretation 
of 110(l) or characterization of what was provided to EPA. As was 
explained above, EPA has concluded that the interpretation of 110(l) 
that is most consistent with the plain text, legislative history, and 
air quality goals of the CAA is that in order to approve the SIP 
revision, there must be some reasonable basis for concluding that the 
SIP revision will not interfere with attainment or maintenance of the 
NAAQS, consistent with the requirements of 110(l). As commenters 
acknowledged, the evaluation for this particular SIP revision is 
challenging due to the inherent uncertainty in the relationship between 
opacity and PM mass emissions at a given source. For this reason, it is 
even more important that the demonstration be sufficient to ensure that 
EPA is complying with section 110(l).
    A fundamental purpose of 110(l) is to allow SIP revisions in the 
absence of a full attainment demonstration provided that such revisions 
are consistent with continued attainment and maintenance of the NAAQS. 
To the extent that emission increases of a particular SIP revision 
cannot be modeled with some level of certainty regarding impact on the 
NAAQS, section 110(l) may bar that SIP revision, absent equivalent 
offsetting emissions reductions and in the absence of an attainment or 
maintenance demonstration. In EPA's judgment, the analysis submitted in 
connection with the SIP revisions at issue here fails to provide a 
reasonable basis on which to conclude that the changes would not 
interfere with attainment and maintenance of the NAAQS. EPA concludes 
that the CAA prohibits this SIP revision because air emissions could be 
allowed to increase and thus, worsen air quality in nonattainment 
areas.
    Comment 50. Commenters argued that there is no basis for reversing 
EPA's prior analysis because the current SIP ensures opacity will be 
equal to or lower than that allowed under the previous SIP. Commenters 
further stated that EPA demonstrated mathematically that both the 
suggested changes in its 2007 proposal to approve the Rule and in 
Alabama's 2008 revisions as submitted are at least as stringent as 
Alabama's existing SIP and even more stringent than the 2003 revisions.
    Response 50. As discussed above, EPA has concluded after 
reconsideration that it is not appropriate to measure the stringency of 
the SIP revisions in the Submittals using an

[[Page 18889]]

``average daily limit.'' Alabama's revised rule allows for extended 
periods of operation at high levels of opacity that were not previously 
authorized. Absent a showing that a source's PM emissions would not be 
elevated if it was permitted to have opacity at up to 100 percent for 
up to 2.4 hours a day, EPA has concluded that the SIP revisions would 
be inconsistent with section 110(l).
    Comment 51. Commenters argued that Alabama has made an affirmative 
demonstration that the visible emissions standards in the previous SIP 
and the revised SIP are equivalent. Alabama's previous visible 
emissions rule allowed opacity of up to 40 percent for one six-minute 
period per hour. The revised rule allows the same maximum time of 
higher opacity in a single day (up to 144 minutes per day), but 
eliminates the 40 percent cap. To assure equivalency with the previous 
rule, the revised SIP limits the daily average opacity to less than 22 
percent. The basis for derivation of the 22 percent limit was clearly 
set out in EPA's final rule. 73 FR at 60958-59 (October 15, 2008).
    Response 51. As explained above, as a result of this 
reconsideration EPA disagrees that the two versions of the visible 
emissions rules could be equivalent, as explained in detail in the Rule 
Comparison TSD included in the docket. Ultimately, if the impacts of 
the two versions were actually equivalent, there would be no reason for 
Alabama to seek the SIP revisions. The practical reality is that the 
revised rule allows for opacity increases not previously authorized 
(both in concentration and quantity of time). Furthermore, the rule at 
issue specifically affects facilities which for one reason or another 
are not subject to any other opacity limit--and thus this opacity limit 
is particularly important both for air quality and as an indicator of 
facility O & M. While EPA understands the commenters' concerns, EPA 
does not agree that the two versions of the visible emissions rules are 
equivalent.
    Comment 52. One commenter stated that EPA's approval was entirely 
consistent with section 110(l). According to the commenter, EPA made an 
``appropriate inquiry'' under section 110(l) to protect the NAAQS 
because it made an equivalency determination and did not rely solely on 
uncertainty as a basis for the approval. This commenter believes that 
any uncertainty is erased by the 22 percent cap.
    Response 52. EPA's October 15, 2008, final action relied heavily on 
the uncertainty inherent in the relationship between opacity and PM 
mass emissions. The October 15, 2008, action was different from other 
110(l) analyses previously completed by EPA for that reason. EPA agrees 
that this rule presents particularly complex technical issues but has 
ultimately decided that heavy reliance on uncertainty as a basis for 
approval is not the decision most consistent with the CAA. Section 
110(l) is intended to preclude SIP revisions that could have adverse 
consequences for public health, and accordingly EPA thinks that it 
should continue to interpret the provision using a precautionary 
principle to ensure such public health protection in the face of 
uncertainty about the impacts of a SIP revision.
    Comment 53. Commenters drew comparisons between Ohio's recent 
opacity proposal and North Carolina's previous opacity proposal and 
concluded that Alabama's opacity limits are far below those of other 
states (specifically, North Carolina and Georgia).
    Response 53. EPA does not agree with commenters' assessment of 
opacity requirements in other states. Alabama's revised rule was unique 
in that it allows opacity of up to 100 percent (not allowed under the 
recent North Carolina revisions)--and it allows such opacity for up to 
2.4 consecutive hours. Opacity revisions, by nature, require detailed 
case-by-case analyses. Due to the specific circumstances of a state 
(i.e., attainment status, affected facilities, topography, 
etc[hellip]), it is difficult to directly compare opacity rules from 
state to state (or SIP to SIP). While previous opacity decisions are 
informative, no other state presents a circumstance totally analogous 
to Alabama's circumstances. In addition, EPA has proposed to disapprove 
comparable revisions to the visible emissions rules in the Ohio SIP for 
reasons comparable to those described in this final action.

9. Use of COMS and Need for Exemptions

    Comment 54. One commenter argued that without a regulatory 
mechanism to address excess emissions reported from COMS, such as that 
used by Alabama, sources are vulnerable to enforcement actions for 
short term opacity excursions that have negligible environmental 
effects.
    Response 54. The environmental effect of individual ``short-term'' 
opacity excursions depends upon the duration and level of such 
exceedances, as well as the relationship between opacity and PM 
emissions at the source where they occur. This is one reason why EPA 
has concluded that use of an ``average daily opacity'' cap, in which 
longer excursions at higher levels are allowed to be ``averaged out'' 
with periods of normal operation at lower opacity levels, does little 
to help reduce PM emissions. Therefore, an ``average daily opacity 
cap'' is not a sufficient basis to approve the proposed SIP revisions. 
Frequent recurrence of such events may reflect the need to improve 
source operation or emission controls in order to comply with the 
opacity limit, but that would be masked by the averaging effect of an 
average daily opacity standard.
    In the case of the visible emissions rule changes at issue in these 
SIP revisions, some sources may have to take action to improve their 
opacity performance in order to comply with the previous SIP rule. 
Finally, today's action does not impede the State's ability to exercise 
its own enforcement discretion in the event that it decides a given 
opacity violation does not warrant such action.
    Comment 55. Commenters explained that when utilizing COMS that 
yield opacity data for nearly 100 percent of source operating time, 
given the extremely short data averages utilized for opacity data (six-
minute data averages), time periods of excess occur from even the best 
operated sources.
    Response 55. EPA acknowledges that some sources may have difficulty 
in complying with 20 percent opacity limits 100 percent of the time, 
especially when events out of the source's control occur, but EPA 
expects that all sources can comply with the pre-existing version of 
the visible emissions rule that will be in place as a result of today's 
disapproval action. EPA expects that any unusual difficulties for 
specific sources would ease as sources subject to Alabama's visible 
emissions rule take steps to improve their opacity performance.
    Comment 56. One commenter explained that 40 CFR 60.284(e) is the 
recognition by EPA that some type of exemption time period is necessary 
when opacity regulations are enforced by a continuous in-stack 
monitoring system and that this regulation is probably the basis of the 
Alabama SIP revisions. The commenter further explained its view that 
the ``the preamble to both the NSPS (40 CFR 60.7(c)) and the MACT 
[maximum achievable control technology] (40 CFR 63.10(e)(3))'' both 
state that sources required to submit reports of excess emissions from 
continuous in-stack monitoring systems are only required to submit 
summary reports of the excess emissions data and not detailed reports, 
provided that the total duration of excess is less than one percent of 
the

[[Page 18890]]

total operating time of the monitored source for the operating time 
period and that the monitor downtime is less than five percent of the 
total operating time of the monitored source for the reporting time 
period. The commenter considered these two regulations as a ``de 
facto'' recognition by EPA of [the need for] exemption time periods 
similar to that proposed in the Alabama SIP revisions.
    Response 56. EPA disagrees with the premise of the comment, as it 
misses the mark concerning what is relevant in the context of a SIP 
revision for purposes of section 110(l). The NSPS and SIPs serve 
different purposes under the CAA. The NSPS are industry-specific 
nationally uniform air emission standards that limit the amount of 
emissions allowed from new sources or from modified existing sources. 
They are technology-based standards, meaning that they contain 
industry-specific limitations based on the best available technology. 
Under section 111 of the CAA, a standard of performance must reflect 
the degree of emission limitation and the percentage reduction 
achievable through application of the best technological system of 
continuous emission reduction that the Administrator determines has 
been adequately demonstrated. Such determinations take into 
consideration the cost of achieving such emission reduction and any 
non-air quality health and environmental impact and energy 
requirements. The fact that such standards contain various reporting 
requirements about excess emissions does not address the issues 
relevant to an analysis to support a SIP revision.
    SIPs are EPA-approved state plans for the establishment, 
regulation, and enforcement of air pollution standards--the NAAQS. 
Under section 110 of the Act, each state must adopt a plan to provide 
for implementation, maintenance, and enforcement of the primary and 
secondary NAAQS within the state. Because SIPs serve a different 
purpose than the NSPS, EPA evaluates them differently. For example, the 
NSPS provide exemptions from compliance during brief periods such as 
startup, shutdown, and malfunctions (SSM). Such automatic exemptions 
are not appropriate for SIP rules because SIPs are ambient-based 
standards and any emissions above the allowable may cause or contribute 
to violations of the NAAQS. Generally, because SIPs must provide for 
attainment and maintenance of the NAAQS and the achievement of 
prevention of significant deterioration increments, EPA's policy is 
that all periods of excess emissions must be considered violations. 
SIPs can contain regulations with affirmative defenses for violations 
that occur due to events not reasonably within the control of the 
source, but they should not contain automatic exemptions. EPA's policy 
with respect to appropriate SIP provisions is contained in the 1999 
memorandum entitled ``State Implementation Plans (SIPs): Policy 
Regarding Excess Emissions During Malfunctions, Startup, and 
Shutdown.''
    Comment 57. Commenters explained that despite its best efforts, 
continuous compliance with the 20 percent opacity limit is an 
unachievable goal, and imposing penalties for failing to achieve an 
unattainable goal does not promote continuous, long term environmental 
improvement.
    Response 57. EPA's final action does not impose penalties or 
implicate any specific enforcement actions. Rather, it simply finds 
that Alabama's revisions to its visible emissions rule are not 
approvable under section 110(l) of the CAA. EPA encourages the 
commenter to discuss specific compliance concerns with ADEM. Sources 
should generally be capable of complying with the Alabama opacity rule, 
but we remain open to considering further SIP revisions that provide 
greater assurance that PM emissions will not increase as a result.

10. Relationship of SIP Revisions to 40 CFR 51.212

    Comment 58. Commenters argued that the visible emissions rule in 
the revised SIP is appropriate under 40 CFR 51.212(b). Some commenters 
also discussed that the ``indirect'' use of COMS for compliance 
determinations adopted by Alabama and many other states is based on the 
approach adopted by EPA under the NSPS, which also specify Method 9 as 
the compliance method but require reporting of COMS data as an 
indicator of good control device O & M. The commenters asserted that 
because ADEM's rule continues to use COMS data as an indicator of good 
O & M, but now simply provides an option for its use ``directly * * * 
for compliance determinations,'' respecting the independently 
enforceable opacity limit as allowed under Appendix P, the rule 
continues to meet EPA's criteria. Other commenters highlighted the 
position that 51.212 provides states with discretion and the Alabama 
rule enhances enforcement through use of COMS.
    Response 58. In the present action, EPA is not evaluating the 
approvability of the SIP revision to Alabama's visible emission rule 
revisions in light of the requirements of 40 CFR 51.212. While EPA 
agrees that this provision requires states to have SIPs with 
appropriate methods to assure compliance with emissions limits, EPA is 
not here addressing whether the revisions at issue would or would not 
meet those requirements. EPA's analysis for the present action focused 
on the section 110(l) limitations on EPA's authority to approve a SIP 
revision. Even if Alabama's revised visible emissions rule were 
consistent with section 51.212, this would not alleviate the concerns 
that EPA has with respect to section 110(l).
    Comment 59. Commenters stated that ADEM's two percent criterion is 
consistent with policies developed by EPA in the 1980s to support the 
use of continuous monitors. Commenters noted that there is no national 
standard on visible emissions and ADEM's use of a flexible approach is 
consistent with part 51.
    Response 59. In the present rulemaking, EPA is not articulating a 
position on ADEM's enforcement discretion or policies regarding 
enforcement discretion, although EPA is aware of the fairly recent 
Eleventh Circuit Court's opinion addressing ADEM's enforcement 
discretion in a visible emissions context. As was explained earlier, 
EPA acknowledges the various comments that support ADEM's Submittals by 
citing to other federal requirements. However, EPA's analysis was 
focused on its authority under section 110, and the review of ADEM's 
Submittals that is most supported by the CAA.

11. Relationship of SIP Revisions to Compliance Assurance Monitoring 
(CAM) Rule

    Comment 60. Commenters explained that although Alabama's visible 
emissions rule may have some role in evaluating long-term PM control 
device operation, it is no longer the primary means by which major 
sources assure compliance with SIP limits on PM. Commenters believe 
that this role is now filled by EPA's CAM rule at 40 CFR part 64.
    Response 60. EPA's present action is not dependent upon whether the 
State's visible emissions rule is the ``primary'' means for evaluating 
compliance with PM limits, although that has been and continues to be a 
legitimate reason for such opacity limits in SIPs. EPA's present action 
is based primarily on its obligation under section 110(l) not to 
approve SIP revisions that would interfere with attainment or 
maintenance of the NAAQS or other applicable requirements of the CAA. 
EPA agrees that the CAM rule provides additional support for evaluation 
of

[[Page 18891]]

control device operation; however, CAM applicability and methodologies 
vary from facility-to-facility. The CAM rule is designed to provide 
reasonable assurance of ongoing compliance with applicable emissions 
limits, such as the PM emission limits of the SIP. But CAM requirements 
are in addition to the requirements of Alabama's visible emissions 
rule; as a result, the commenters' statements do not resolve whether 
the revisions to the visible emissions rule satisfy section 110(l).

12. Relationship of SIP Revisions to Sierra Club v. EPA, 551 F.3d 1019 
(D.C. Cir. 2008), and the Vacatur of Certain Provisions in 40 CFR Part 
63

    Comment 61. Commenters explained that the D.C. Circuit Court's 
vacatur of 40 CFR part 63 provisions pertaining to SSM and its impact 
on the opacity SIP revision are irrelevant. Further, commenters noted 
that SSM provisions are not at issue in the instant SIP revision.
    Response 61. EPA does not agree with the blanket statement that SSM 
provisions are not at issue in the instant SIP revision. As part of 
EPA's 110(l) evaluation, EPA may consider the SIP as a whole--including 
other provisions, such as SSM provisions, that may further affect the 
consequences of a given SIP revision. In this case, EPA's analysis 
focused primarily on the provisions of the visible emissions rule that 
the State actually sought to change in the Submittals. However, EPA may 
consider the entirety of a rule, and the SIP, in completing a 110(l) 
analysis.

13. Relationship of SIP Revisions to Reasonably Available Control 
Technology (RACT)

    Comment 62. Commenters explained that the Submittals on opacity are 
not required to comply with RACT and that there is no requirement for 
EPA to review ``unrelated SIP revisions requests'' for future RACT 
compliance. Moreover, commenters stated that when Alabama does submit a 
SIP revision to address RACT, EPA is not compelled to require that 
revision to establish any particular opacity standard. Another 
commenter stated that Alabama's revised SIP imposes the proper opacity 
RACT standard. Several commenters noted that the Petitioners will have 
separate opportunity to challenge RACT determinations is RACT-specific 
rulemaking.
    Response 62. RACT refers to equipment and practices that reduce 
pollutant emissions that are reasonably available and both 
technologically and economically feasible. RACT usually applies to 
existing sources in nonattainment areas. Since EPA has concluded that 
this revision is not approvable under section 110(l) for the reasons 
already stated, it is not necessary to determine whether Alabama has 
relied on opacity limits to meet its RACT obligations.
    Notably, section 172 of the Act, Nonattainment plan provisions in 
general, requires nonattainment plans ``shall provide for the 
implementation of all reasonably available control measures as 
expeditiously as practicable (including such reductions in emissions 
from existing sources in the area as may be obtained through the 
adoption, at a minimum, of reasonably available control technology) and 
shall provide for attainment of the national primary ambient air 
quality standards.'' Section 172 requirements, including RACT, are 
applicable requirements of the CAA which section 110(l) evaluations may 
consider.
    Section 110(l) requires that EPA consider whether the revision at 
issue would interfere with the NAAQS, and any other applicable 
requirement concerning attainment and RFP. Thus, EPA is authorized to 
consider whether the revision would interfere with an area's ability to 
comply with RACT or other requirements in the SIP. In this case, 
however, EPA's review was primarily focused on interference with the 
NAAQS. While some applicable requirements may be subject to separate 
SIP revisions, as was noted by several commenters, that does not mean 
that EPA is prohibited from considering whether revision of a rule at 
issue may implicate another applicable requirement. RACT issues are 
likely to also be addressed separately in other SIP revisions.

14. Other Exemptions in Alabama SIP Related to Visible Emissions

    Comment 63. Commenters noted that EPA's final action was not 
inconsistent with EPA policies on excess emissions and director's 
discretion.
    Response 63. As was previously noted by EPA in the 2007 proposal 
and the October 2008, action, the director's discretion provisions 
under Alabama rule 335-3-4-.01(1)(c) and (d) are unchanged by the SIP 
revisions. As a result, periods of excess emissions allowed in a permit 
pursuant to those provisions remain unchanged under Alabama's rules. 
EPA did, however, consider Alabama's provisions for excess emissions in 
evaluating the rule as a whole and comparing it with the previous EPA-
approved SIP rule. These types of details become relevant, particularly 
when parties compare Alabama's visible emissions rules with those in 
other states. In this action, EPA is not taking any action on Alabama's 
existing SIP-approved rules that implicate director's discretion and 
excess emissions.

IV. Final Action

    EPA is taking final action to amend an October 15, 2008, final 
rulemaking on two SIP revisions regarding the State of Alabama's rules 
for visible emissions from certain stationary sources. EPA has now 
determined upon reconsideration that Alabama's SIP revisions, dated 
September 11, 2003, and August 22, 2008, are not approvable pursuant to 
CAA section 110(l). Accordingly, EPA is now disapproving the revisions 
submitted by the State of Alabama on September 11, 2003, and August 22, 
2008. As a result of this action, Alabama's visible emissions rule that 
was in the SIP prior to the October 15, 2008, final action will be the 
``current'' SIP-approved rule. Alabama is urged to undertake rulemaking 
in order to conform its SIP-approved rule with its State-effective 
rule.

V. Statutory and Executive Order Reviews

A. Executive Order 12866, Regulatory Planning and Review

    This final action has been determined to be a ``significant 
regulatory action'' subject to review by the Office of Management and 
Budget (OMB) under Executive Order 12866 (58 FR 51735, October 4, 
1993). Accordingly, EPA submitted this action to the Office of 
Management and Budget (OMB) for review under Executive Order 12866 and 
any changes made in response to OMB recommendations have been 
documented in the docket for this action.

B. Paperwork Reduction Act

    This action does not impose an information collection burden under 
the provisions of the Paperwork Reduction Act, 44 U.S.C. 3501 et seq., 
because these SIP disapprovals under section 110 will not in-and-of 
itself create any new information collection burdens but simply 
disapproves certain State requirements for inclusion into the SIP. 
Burden is defined at 5 CFR 1320.3(b).

C. Regulatory Flexibility Act (RFA)

    The RFA generally requires an agency to conduct a regulatory 
flexibility analysis of any rule subject to notice and comment 
rulemaking requirements unless the agency certifies that the rule will 
not have a significant economic impact on a substantial number of small 
entities. Small entities include small businesses, small not-for-profit

[[Page 18892]]

enterprises, and small governmental jurisdictions. For purposes of 
assessing the impacts of today's rule on small entities, small entity 
is defined as: (1) A small business as defined by the Small Business 
Administration's regulations at 13 CFR 121.201; (2) a small 
governmental jurisdiction that is a government of a city, county, town, 
school district or special district with a population of less than 
50,000; and (3) a small organization that is any not-for-profit 
enterprise which is independently owned and operated and is not 
dominant in its field. This rule will not have a significant impact on 
a substantial number of small entities because EPA understands that 
only one small entity will be affected by this rule. Furthermore, even 
if additional small entities were affected by this rule, this rule 
would not have a significant economic impact on any small entity 
because it simply restores a long-standing requirement of the Alabama 
SIP concerning visible emissions.
    Therefore, after considering the economic impacts of today's 
rulemaking on small entities, I certify that this action will not have 
a significant economic impact on a substantial number of small 
entities.

D. Unfunded Mandates Reform Act

    This action contains no Federal mandates under the provisions of 
Title II of the Unfunded Mandates Reform Act of 1995, 2 U.S.C. 1531-
1538 ``for State, local, or tribal governments or the private sector.'' 
EPA has determined that the disapproval action does not include a 
Federal mandate that may result in estimated costs of $100 million or 
more to either State, local, or tribal governments in the aggregate, or 
to the private sector. This Federal action determines that pre-existing 
requirements under State or local law should not be approved as part of 
the Federally approved SIP. It imposes no new requirements. 
Accordingly, no additional costs to State, local, or tribal 
governments, or to the private sector, result from this action.

E. Executive Order 13132, Federalism

    Executive Order 13132, entitled ``Federalism'' (64 FR 43255, August 
10, 1999), requires EPA to develop an accountable process to ensure 
``meaningful and timely input by State and local officials in the 
development of regulatory policies that have Federalism implications.'' 
``Policies that have Federalism implications'' is defined in the 
Executive Order to include regulations that have ``substantial direct 
effects on the States, on the relationship between the national 
government and the States, or on the distribution of power and 
responsibilities among the various levels of government.''
    This action does not have Federalism implications. It will not have 
substantial direct effects on the States, on the relationship between 
the national government and the States, or on the distribution of power 
and responsibilities among the various levels of government, as 
specified in Executive Order 13132, because it merely disapproves 
certain State requirements for inclusion into the SIP and does not 
alter the relationship or the distribution of power and 
responsibilities established in the CAA. Thus, Executive Order 13132 
does not apply to this action.

F. Executive Order 13175, Coordination With Indian Tribal Governments

    This action does not have tribal implications, as specified in 
Executive Order 13175 (59 FR 22951, November 9, 2000), because the SIP 
EPA is disapproving would not 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. This final rule does not 
have tribal implications, as specified in Executive Order 13175. It 
will not have substantial direct effects on tribal governments, on the 
relationship between the Federal government and Indian tribes, or on 
the distribution of power and responsibilities between the Federal 
government and Indian tribes. This action does not involve or impose 
any requirements that affect Indian Tribes. Thus, Executive Order 13175 
does not apply to this action.

G. Executive Order 13045, Protection of Children From Environmental 
Health Risks and Safety Risks

    EPA interprets Executive Order 13045 (62 FR 19885, April 23, 1997) 
as applying only to those regulatory actions that concern health or 
safety risks, such that the analysis required under section 5-501 of 
the Executive Order has the potential to influence the regulation. This 
action is not subject to Executive Order 13045 because it is not an 
economically significant regulatory action based on health or safety 
risks subject to Executive Order 13045 (62 FR 19885, April 23, 1997). 
This SIP disapproval under section 110 will not in-and-of itself create 
any new rules but simply disapproves certain State requirements for 
inclusion into the SIP.

H. Executive Order 13211, Actions That Significantly Affect Energy 
Supply, Distribution, or Use

    This action is not a ``significant energy action'' as defined in 
Executive Order 13211 (66 FR 28355 (May 22, 2001)), because it is not 
likely to have a significant adverse effect on the supply, 
distribution, or use of energy. We have concluded this rule is not 
likely to have a significant adverse effect on the supply, distribution 
or use of energy because this rule applies only to 19 facilities in 
Alabama and simply restores a long-standing rule concerning visible 
emissions.

I. National Technology Transfer and Advancement Act (NTTAA)

    Section 12(d) of the NTTAA of 1995 (NTTAA), Public Law 104-113, 
section 12(d) (15 U.S.C. 272 note) directs EPA to use voluntary 
consensus standards (VCS) in its regulatory activities unless to do so 
would be inconsistent with applicable law or otherwise impractical. VCS 
are technical standards (e.g., materials specifications, test methods, 
sampling procedures, and business practices) that are developed or 
adopted by VCS bodies. NTTAA directs EPA to provide Congress, through 
the OMB, explanations when the Agency decides not to use available and 
applicable VCS.
    EPA believes that this action is not subject to requirements of 
Section 12(d) of NTTAA because application of those requirements would 
be inconsistent with the CAA. Today's action does not require the 
public to perform activities conducive to the use of VCS.

J. Executive Order 12898: Federal Actions To Address Environmental 
Justice in Minority Populations and Low-Income Populations

    Executive Order 12898 (59 FR 7629, (February 16, 1994)) establishes 
Federal executive policy on environmental justice. Its main provision 
directs Federal agencies, to the greatest extent practicable and 
permitted by law, to make environmental justice part of their mission 
by identifying and addressing, as appropriate, disproportionately high 
and adverse human health or environmental effects of their programs, 
policies, and activities on minority populations and low-income 
populations in the United States.
    EPA lacks the discretionary authority to address environmental 
justice in this action. In reviewing SIP submissions, EPA's role is to 
approve or disapprove State choices, based on the criteria of the CAA. 
Accordingly, this action merely disapproves certain State requirements 
for inclusion into the SIP

[[Page 18893]]

under section 110. Accordingly, it 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.

K. Congressional Review Act

    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 rule 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). This rule will be effective May 6, 2011.

L. Petitions for Judicial Review

    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 June 6, 2011. Filing a petition for 
reconsideration by the Administrator of this final rule does not affect 
the finality of this rule 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 CAA 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: March 29, 2011.
Gwendolyn Keyes Fleming,
Regional Administrator, Region 4.

    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
--------------------------------------------------------------------------------------------------------------------------------------------------------
 
                                                                      * * * * * * *
Section 335-3-4-.01...............  Visible Emissions....      10/15/1996  4/6/2011 [Insert citation of
                                                                            publication].
 
                                                                      * * * * * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------

* * * * *
[FR Doc. 2011-8032 Filed 4-5-11; 8:45 am]
BILLING CODE 6560-50-P