proposed FIP. We will also review and take action on any regional haze
SIP submitted by the state to determine whether such SIP is approvable,
regardless of whether or not its terms match those of the FIP. We
encourage the State to submit a SIP revision to replace the FIP, either
before or after our final action.

A. Disapproval of the State's NOX BART Determinations and
Federal Implementation Plan for NOX BART Determinations and
Limits

    As noted above, the State provided five-factor analyses that
considered all factors, but we find that its

consideration of the costs of compliance and visibility improvement was
inconsistent with regulatory and statutory requirements. In
disapproving specific State BART determinations in our proposed
rulemaking notice on June 4, 2012, we based our analysis on information
provided by the State in their BART analyses, with the exception of
visibility improvement modeling, and thus accepted the cost information
provided by the State. In this proposed rulemaking, in addition to the
other BART information in the State SIP submittal, we are basing our
proposed BART determinations on cost analyses and visibility
improvement modeling developed by EPA, as explained in section VII.C of
this notice. EPA is proposing to disapprove the State's NOX
BART determinations, and we are proposing to issue a BART FIP, for the
following units: PacifiCorp Dave Johnston Unit 3 and Unit 4, PacifiCorp
Naughton Unit 1 and Unit 2, PacifiCorp Wyodak Unit 1, and Basin
Electric Laramie River Units 1, 2, and 3. EPA's rationale for
disapproving the State's BART determinations for these units, as well
as EPA's BART FIP determinations and emission limits, are discussed
below.
    We are also asking if interested parties have additional
information or comments regarding the BART factors and EPA's proposed
determinations, for example our weighing of average costs, incremental
costs, visibility improvement, and timing of installation of such
controls, and in light of such information, whether the interested
parties think the Agency should consider another BART control
technology option that could be finalized either instead of, or in
conjunction with, BART as proposed. The Agency is also asking if
interested parties have additional information or comments on the
proposed timing of compliance when the challenge of coordinating the
work our proposed SIP and FIP will require is considered.
    The Agency will take the comments and testimony received, as well
as any further SIP revisions submitted by the State, into consideration
in our final promulgation. Supplemental information received may lead
the Agency to adopt final SIP and/or FIP regulations that reflect a
different BART control technology option, or impact other proposed
regulatory provisions, which differ from this proposal.
1. Disapproval of the State's Basin Electric Laramie River Units 1-3
NOX BART Determination and FIP to Address NOX
BART
Wyoming's NOX BART Determination
    During the 2001-2003 baseline, Basin Electric Laramie River Units
1-3 were all controlled with LNBs with a permit limit of 0.5 lbs/MMBtu
(3-hour rolling average). The State determined that new LNBs, OFA, new
LNBs and OFA, new SNCR/SCR hybrid \50\, new LNBs and OFA with SNCR, and
SCR were technically feasible for reducing NOX emissions at
Units 1-3. The State determined that natural gas re-burn was
technically infeasible. The State did not identify any energy or non-
air quality environmental impacts that would preclude the selection of
any of the controls evaluated, and there are no remaining-useful-life
issues for this source. A summary of the State's NOX BART
analysis is provided in Tables 36-38 below. As discussed above, the
visibility improvement modeling results in these tables were developed
by EPA because Wyoming did not properly follow the BART Guidelines.
Baseline NOX emissions are 6,320 tpy for Unit 1, 6,285 tpy
for Unit 2, and 6,448 tpy for Unit 3 based on annual average heat input
for 2001-2003 and an emission rate of 0.27 lb/MMBtu.
---------------------------------------------------------------------------

    \50\ A hybrid SNCR/SCR system combines the lower costs and
higher ammonia slip of SNCR with the higher NOx reduction potential
and lower ammonia slip of SCR. During operation, the SNCR system is
allowed to inject higher amounts of reagent into the flue gas. The
increased reagent flow brings about increased NOx reduction, but
also causes increased ammonia slip which is then consumed by the SCR
system. The use of the ammonia slip by the SCR system can reduce the
size of the required SCR catalyst.

                                  Table 36--Summary of Wyoming's Basin Electric Laramie River Unit 1 NOX BART Analysis
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Visibility
                                                                                improvement
                                                                                (delta dv for
                                                           Emission rate                                                                    the maximum
                                                            (lb/MMBtu)       Emission       Annualized     Average cost     Incremental        98th
                   Control technology                         (30-day        reduction         costs       effectiveness       cost         percentile
                                                              rolling          (tpy)                          ($/ton)      effectiveness  impact at Wind
                                                             average)                                                                      Cave National
                                                                                Park) EPA
                                                                                analysis
--------------------------------------------------------------------------------------------------------------------------------------------------------
OFA.....................................................            0.23             936        $625,000            $668  ..............            0.08
New LNBs................................................            0.23             936       1,360,000           1,453  ..............            0.08
New LNBs with OFA.......................................            0.23             936       1,944,000           2,077  ..............            0.08
SNCR/SCR Hybrid.........................................            0.20           1,639       7,429,000           4,534  ..............  ..............
New LNBs with OFA and SNCR..............................            0.12           3,511       7,365,000           2,098          $2,105            0.32
SCR.....................................................            0.07           4,681      15,787,000           3,372           7,198            0.44
--------------------------------------------------------------------------------------------------------------------------------------------------------

                                  Table 37--Summary of Wyoming's Basin Electric Laramie River Unit 2 NOX BART Analysis
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Visibility
                                                                                improvement
                                                                                (delta dv for
                                                           Emission rate                                                                    the maximum
                                                            (lb/MMBtu)       Emission       Annualized     Average cost     Incremental        98th
                   Control technology                         (30-day        reduction         costs       effectiveness       cost         percentile
                                                              rolling          (tpy)                          ($/ton)      effectiveness  impact at Wind
                                                             average)                                                                      Cave National
                                                                                Park) EPA
                                                                                analysis
--------------------------------------------------------------------------------------------------------------------------------------------------------
OFA.....................................................            0.23             931        $625,000            $671  ..............            0.08

New LNBs................................................            0.23             931      $1,360,000          $1,461  ..............            0.08
New LNBs with OFA.......................................            0.23             931       1,944,000           2,088  ..............            0.08
SNCR/SCR Hybrid.........................................            0.20           1,630       7,429,000           4,559  ..............  ..............
New LNBs with OFA and SNCR..............................            0.12           3,492       7,365,000           2,109          $2,117            0.32
SCR.....................................................            0.07           4,656      15,787,000           3,391           7,242            0.44
--------------------------------------------------------------------------------------------------------------------------------------------------------

                                  Table 38--Summary of Wyoming's Basin Electric Laramie River Unit 3 NOX BART Analysis
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Visibility
                                                                                improvement
                                                                                (delta dv for
                                                           Emission rate                                                                    the maximum
                                                            (lb/MMBtu)       Emission       Annualized     Average cost     Incremental        98th
                   Control technology                         (30-day        reduction         costs       effectiveness       cost         percentile
                                                              rolling          (tpy)                          ($/ton)      effectiveness  impact at Wind
                                                             average)                                                                      Cave National
                                                                                Park) EPA
                                                                                analysis
--------------------------------------------------------------------------------------------------------------------------------------------------------
OFA.....................................................            0.23             955        $625,000            $654  ..............            0.08
New LNBs................................................            0.23             955       1,360,000           1,424  ..............            0.08
New LNBs with OFA.......................................            0.23             955       1,944,000           2,036  ..............            0.08
SNCR/SCR Hybrid.........................................            0.20           1,672       7,429,000           4,444  ..............  ..............
New LNBs with OFA and SNCR..............................            0.12           3,582       7,365,000           2,056          $2,064            0.33
SCR.....................................................            0.07           4,777      15,787,000           3,305           7,054            0.44
--------------------------------------------------------------------------------------------------------------------------------------------------------

    The State eliminated the SNCR/SCR hybrid from further consideration
because it has higher cost-effectiveness values and lower control
efficiency compared to new LNBs plus OFA with SNCR.
    Based on its consideration of the five factors, the State
determined that new LNBs with OFA were reasonable for NOX
BART. The State determined that the NOX BART emission limit
for Laramie River Unit 1 is 0.23 lb/MMBtu (30-day rolling average). The
State determined that the NOX BART emission limit for
Laramie River Unit 2 is 0.23 lb/MMBtu (30-day rolling average). The
State determined that the NOX BART emission limit for
Laramie River Unit 3 is 0.23 lb/MMBtu (30-day rolling average).
    The State's proposed SIP required additional NOX
emission reductions for Laramie River under its LTS. Based on the costs
and visibility improvement for Laramie River Station Units 1, 2, and 3,
the State proposed installation of two SCRs, or equivalent performing
emission control systems, at any of the three units. The State proposed
that the add-on NOX control achieve an emission rate, on an
individual unit basis, at or below 0.07 lb/MMBtu on a 30-day rolling
average. The State proposed that the add-on controls be installed and
operational on one of the Laramie River Station units by December 31,
2018 and on a second Laramie River Station unit by December 31, 2023.
    On March 8, 2010, Basin Electric Power Cooperative appealed the
additional controls proposed by the State under its LTS before the
Wyoming Environmental Quality Council. The State entered into a
settlement agreement on November 16, 2010 with Basin Electric Power
Cooperative (a copy of the settlement agreement is included in the
State's revised NOX BART Analysis for Laramie River dated
January 3, 2011). As part of the settlement agreement, the State agreed
to remove the requirement for Basin Electric to install additional
controls under the LTS. In return, Basin Electric agreed to additional
NOX emissions reductions under BART. Under the settlement
agreement, Basin Electric agreed to a NOX emission limit of
0.21 lb/MMBtu (30-day rolling average) on all three units. Basin
Electric also agreed to a NOX emission limit for Unit 1 and
Unit 2 of 4,780 tpy and a NOX emission limit for Unit 3 of
4,914 tpy, effectively capping emissions from all three units at 12,773
tpy. In the SIP adopted by the State, the State determined the emission
limits in the settlement agreement were BART for Basin Electric Laramie
River Units 1, 2, and 3.
EPA's Basin Electric Laramie River Units 1-3 NOX BART
Determination and FIP for NOX BART
    The EPA agrees with the State's analysis pertaining to energy or
non-air quality environmental impacts and remaining-useful-life for
this source. However, EPA disagrees with the State's baseline
NOX emissions estimates, as listed above, because the State
based its estimate on annual average heat input for 2001-2003 at an
emission rate of 0.07 lb/MMBtu and not actual annual averages. EPA's
revised baseline NOX emissions are 6,051 tpy for Unit 1,
6,293 tpy for Unit 2, and 6,375 tpy for Unit 3 based on the actual
annual average for the years 2001-2003. A summary of the EPA's
NOX BART analysis and the visibility impacts is provided in
Tables 39-44 below.

                                            Table 39--Summary of EPA's Laramie River Unit 1 NOX BART Analysis
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Visibility
                                                                                improvement
                                                           Emission rate                                                                   (delta dv for
                                                            (lb/MMBtu)       Emission       Annualized     Average cost     Incremental     the maximum
                   Control technology                         (annual        reduction         costs       effectiveness       cost            98th
                                                             average)          (tpy)                          ($/ton)      effectiveness    percentile
                                                                                impact at
                                                                                Badlands)
--------------------------------------------------------------------------------------------------------------------------------------------------------
New LNBs with OFA.......................................            0.19           1,556      $2,268,806          $1,458  ..............            0.29
New LNBs with OFA and SNCR..............................            0.15           2,445       5,880,822           2,395          $4,018            0.44
New LNBs with OFA and SCR...............................            0.05           4,880      18,146,629           3,718           5,057            0.79
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Laramie River Unit 1 also impacts other Class I areas. The
visibility improvement modeled by EPA at other Class I areas is shown
in Table 40 below.

                  Table 40--Laramie River Unit 1: Visibility Improvement at Other Class I Areas
----------------------------------------------------------------------------------------------------------------
                                                               Visibility        Visibility        Visibility
                                                               improvement       improvement       improvement
                                                              (delta dv for     (delta dv for     (delta dv for
                       Class I area                         the maximum 98th  the maximum 98th  the maximum 98th
                                                               percentile        percentile        percentile
                                                              impact) - new     impact) - new     impact) - new
                                                               LNBs + OFA      LNBs + OFA/SNCR   LNBs + OFA/SCR
----------------------------------------------------------------------------------------------------------------
Wind Cave.................................................              0.20              0.30              0.64
Rawah.....................................................              0.10              0.16              0.32
Rocky Mountain............................................              0.12              0.19              0.37
----------------------------------------------------------------------------------------------------------------

                                            Table 41--Summary of EPA's Laramie River Unit 2 NOX BART Analysis
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Visibility
                                                                                improvement
                                                           Emission rate                                                                   (delta dv for
                                                            (lb/MMBtu)       Emission       Annualized     Average cost     Incremental     the maximum
                   Control technology                         (annual        reduction         costs       effectiveness       cost            98th
                                                             average)          (tpy)                          ($/ton)      effectiveness    percentile
                                                                                impact at
                                                                                Badlands)
--------------------------------------------------------------------------------------------------------------------------------------------------------
New LNBs with OFA.......................................            0.19            1823      $2,268,806          $1,244  ..............            0.30
New LNBs with OFA and SNCR..............................            0.15           2,717       5,884,257           2,166          $4,044            0.42
New LNBs with OFA and SCR...............................            0.05           5,129      20,017,988           3,903           5,860            0.73
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Laramie River Unit 2 also impacts other Class I areas. The
visibility improvement modeled by EPA at other Class I areas is shown
in Table 42 below.

                  Table 42--Laramie River Unit 2: Visibility Improvement at Other Class I Areas
----------------------------------------------------------------------------------------------------------------
                                                               Visibility        Visibility        Visibility
                                                               improvement       improvement       improvement
                                                              (delta dv for     (delta dv for     (delta dv for
                       Class I area                         the maximum 98th  the maximum 98th  the maximum 98th
                                                               percentile        percentile        percentile
                                                              impact) - new     impact) - new     impact) - new
                                                               LNBs + OFA      LNBs + OFA/SNCR   LNBs + OFA/SCR
----------------------------------------------------------------------------------------------------------------
Wind Cave.................................................              0.24              0.36              0.66
Rawah.....................................................              0.10              0.16              0.29
Rocky Mountain............................................              0.13              0.19              0.35
----------------------------------------------------------------------------------------------------------------

                                            Table 43--Summary of EPA's Laramie River Unit 3 NOX BART Analysis
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Visibility
                                                                                improvement
                                                           Emission rate                                                                   (delta dv for
                                                            (lb/MMBtu)       Emission       Annualized     Average cost     Incremental     the maximum
                   Control technology                         (annual        reduction         costs       effectiveness       cost            98th
                                                             average)          (tpy)                          ($/ton)      effectiveness    percentile
                                                                                impact at
                                                                                Badlands)
--------------------------------------------------------------------------------------------------------------------------------------------------------
New LNBs with OFA.......................................            0.19            1789      $2,268,806          $1,268  ..............            0.22
New LNBs with OFA and SNCR..............................            0.15           2,706       5,933,791           2,192          $3,996            0.33
New LNBs with OFA and SCR...............................            0.05           5,181      18,597,027           3,589           5,117            0.67
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Laramie River Unit 3 also impacts other Class I areas. The
visibility improvement modeled by EPA at other Class I areas is shown
in Table 44 below.

                  Table 44--Laramie River Unit 3: Visibility Improvement at Other Class I Areas
----------------------------------------------------------------------------------------------------------------
                                                               Visibility        Visibility        Visibility
                                                               improvement       improvement       improvement
                                                              (delta dv for     (delta dv for     (delta dv for
                       Class I area                         the maximum 98th  the maximum 98th  the maximum 98th
                                                               percentile        percentile        percentile
                                                              impact) - new     impact) - new     impact) - new
                                                               LNBs + OFA      LNBs + OFA/SNCR   LNBs + OFA/SCR
----------------------------------------------------------------------------------------------------------------
Wind Cave.................................................              0.20              0.31              0.60
Rawah.....................................................              0.10              0.15              0.29
Rocky Mountain............................................              0.12              0.18              0.34
----------------------------------------------------------------------------------------------------------------

    As noted above, under the settlement agreement terms incorporated
into the SIP, Basin Electric agreed to a NOX emission limit
of 0.21 lb/MMBtu (30-day rolling average) on all three units, and thus
eliminated other control options. We propose to find that Wyoming did
not properly follow the requirements of the BART Guidelines in
determining NOX BART for these units.
    Furthermore, as discussed in detail above, because Wyoming relied
on visibility modeling methodologies that are inconsistent with the
statutory and regulatory requirements, we do not consider Wyoming's
analyses of visibility improvement for the NOX BART to be
reasonable for the Laramie units. We propose to find that Wyoming's
analyses for these units are inconsistent with the statutory and
regulatory requirement that ``the degree of improvement in visibility
which may reasonably be anticipated to result from the use of such
technology.''
    Therefore, EPA does not agree with the State's conclusion that a
limit of 0.21 lb/MMBtu is consistent with the BART Guidelines and
reasonable for BART for Laramie River Units 1, 2, and 3, which can be
achieved with the installation and operation of new LNBs with OFA.
Specifically, we propose to find that in negotiating the emission
limit, Wyoming did not properly or reasonably ``take into consideration
the costs of compliance.'' Thus, the State's BART analyses for Basin
Electric Laramie River Units 1, 2, and 3 do not meet the requirements
of the regional haze regulation, and we are proposing to disapprove
those analyses and the State's NOX BART determination. We
are proposing a FIP for NOX BART to fill the gap left by our
disapproval, as explained below.
    Our analysis follows our BART Guidelines. Because the Basin
Electric Laramie River Units 1, 2, and 3 are similar, we are proposing
a single BART analysis and determination that applies to each unit.
With the exception of the NOX emission limits, the
visibility improvement analyses, and the cost-effectiveness analyses,
EPA is proposing to find that the Wyoming regional haze NOX
BART analyses for Units 1, 2 and 3, fulfills all the relevant
requirements of CAA Section 169A and the RHR. As discussed above in
section VII.C.3.b., Wyoming's visibility improvement analyses for these
units is inconsistent with the requirements found in the CAA and BART
Guidelines. Furthermore, we are not relying on the State's costs due to
the reasons described in section VII.C.3.a above.
    In addition, the cost-effectiveness for new LNBs with OFA and SCR
ranges from approximately $3,600/ton to $3,900/ton with significant
visibility improvement at the most impacted Class I area of 0.79 dv for
Unit 1, 0.73 dv for Unit 2, and 0.67 dv for Unit 3. SCR provides
significant visibility improvement at other impacted Class I areas,
with cumulative visibility improvements of 2.12 dv for Unit 1, 1.97 dv
for Unit 2, and 2.29 dv for Unit 3. When considering the cost
effectiveness and visibility improvement of new LNBs plus OFA and SCR,
it is within the range of what EPA has found reasonable for BART in
other SIP and FIP actions. We also propose to find that the incremental
cost-effectiveness does not preclude the selection of new LNBs with OFA
and SCR.
    EPA's NOX BART analyses and the visibility impacts for
Units 1, 2 and 3 is summarized in Tables 39-44 above and detailed
information can be found in the docket.\51\ We propose to find that at
an emission limit of 0.07 lb/MMBtu (30-day rolling average), which can
be achieved by the installation of new LNBs with OFA plus SCR, is
reasonable and consistent with the CAA and BART Guideline requirements
for NOX BART for Basin Electric Laramie River Units 1, 2,
and 3. Consequently, we are proposing that the FIP NOX BART
emission limit for Basin Electric Laramie River Unit 1, Unit 2, and
Unit

3 is 0.07 lb/MMBtu (30-day rolling average).
---------------------------------------------------------------------------

    \51\ Detailed supporting information for our cost and visibility
improvement analyses can be found in the Docket (see Staudt memos
and EPA BART and RP Modeling for Wyoming, respectively).
---------------------------------------------------------------------------

    We propose that Basin Electric meet our proposed emission limit at
Laramie River Units 1, 2, and 3, as expeditiously as practicable, but
no later than five years after EPA finalizes action on our proposed
FIP. This is consistent with the requirements of 40 CFR 51.308(e)(iv).
    We are also asking if interested parties have additional
information regarding the BART factors and EPA's proposed
determination, for example our weighing of average costs, incremental
costs, visibility improvement, and timing of installation of such
controls, and in light of such information, whether the interested
parties think the Agency should consider another BART control
technology option that could be finalized either instead of, or in
conjunction with, BART as proposed. The Agency will take the comments
and testimony received, as well as any further SIP revisions submitted
by the State, into consideration in our final promulgation.
Supplemental information received may lead the Agency to adopt final
SIP and/or FIP regulations that reflect a different BART control
technology option, or impact other proposed regulatory provisions,
which differ from this proposal.
2. Disapproval of the State's PacifiCorp Dave Johnston Unit 3 and Unit
4 NOX BART Determinations and FIP To Address NOX
BART
Wyoming's NOX BART Determination for Dave Johnston Unit 3
    During the baseline period of 2001-2003, Dave Johnston Unit 3 was
uncontrolled for NOX and had emission limits of 0.75 lb/
MMbtu (3-hour rolling) and 0.59 lb/MMbtu (annual). The State determined
LNBs with advanced OFA, LNBs with advanced OFA and SNCR, and LNBs with
advanced OFA and SCR were technically feasible for controlling
NOX emissions from Unit 3. The State did not identify any
technically infeasible controls.
    The State did not identify any energy or non-air quality
environmental impacts that would preclude the selection of any of the
controls evaluated, and there are no remaining-useful-life issues for
this source. Baseline NOX emissions are 5,814 tpy for Unit 3
based on unit heat input rate of 2,500 MMBtu/hr and 7,884 hours of
operation. A summary of the State's NOX BART analysis and
the visibility impacts is provided in Table 45 below. As discussed
above, the visibility improvement modeling results in these tables were
developed by EPA because Wyoming did not properly follow the BART
Guidelines.

                                          Table 45--Summary of Wyoming's Dave Johnston Unit 3 NOX BART Analysis
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Visibility
                                                                                improvement
                                                                                (delta
                                                                                deciview for
                                                           Emission rate     Emission                      Average cost     Incremental     the maximum
                   Control technology                     (lb/MMBtu) (30-    reduction      Annualized     effectiveness       cost            98th
                                                            day rolling        (tpy)           costs          ($/ton)      effectiveness    percentile
                                                             average)                                                                     impact at Wind
                                                                                Cave National
                                                                                Park) EPA
                                                                                analysis
--------------------------------------------------------------------------------------------------------------------------------------------------------
LNB with advanced OFA...................................            0.28           2,723      $1,764,775            $648  ..............            0.77
LNB with advanced OFA and SNCR..........................            0.19           3,717       2,679,192             721            $920            0.94
LNB with advanced OFA and SCR...........................            0.07           5,041      16,347,519           3,243          10,234            1.16
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Based on its consideration of the five factors, the State
determined LNBs with OFA were reasonable for NOX BART. The
State determined the cost of compliance (capital costs and annual
operating and maintenance costs) were significantly higher for the
addition of SCR. The State determined that the NOX BART
emission limit for Unit 3 is 0.28 lb/MMBtu (30-day rolling average).
EPA's Conclusions on Dave Johnston Unit 3 NOX BART
Determination and Proposed FIP for NOX BART
    The EPA agrees with the State's analysis pertaining to energy or
non-air quality environmental impacts and remaining-useful-life for
this source. We disagree with the State's estimate of baseline
NOX emissions (5,814 tpy) because it is based on a unit heat
input rate of 2,500 MMBtu/hr and 7,884 hours of operation rather than
an average of actual annual emissions. EPA finds that baseline
NOX emissions are 4,913 tpy for Unit 3 based on the actual
annual average for the years 2001-2003. A summary of the EPA's
NOX BART analysis and the visibility impacts is provided in
Tables 46 and 47 below.

                                            Table 46--Summary of EPA's Dave Johnston Unit 3 NOX BART Analysis
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Visibility
                                                                                improvement
                                                                                (delta dv for
                                                           Emission rate     Emission                      Average cost     Incremental     the maximum
                   Control technology                       (lb/MMBtu)       reduction      Annualized     effectiveness       cost            98th
                                                              (annual          (tpy)           costs          ($/ton)      effectiveness    percentile
                                                             average)                                                                     impact at Wind
                                                                                Cave National
                                                                                Park)
--------------------------------------------------------------------------------------------------------------------------------------------------------
LNBs with OFA...........................................            0.22           2,837      $1,699,807            $599  ..............            0.64
LNBs with OFA and SNCR..................................            0.16           3,356       3,545,435           1,057          $3,555            0.76
LNBs with OFA and SCR...................................            0.05           4,433      11,262,188           2,540           7,163            1.00
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Dave Johnston Unit 3 also impacts other Class I areas. The
visibility improvement modeled by EPA at other Class I areas is shown
in Table 47 below.

              Table 47--Dave Johnston Unit 3: Visibility Improvement Modeled at Other Class I Areas
----------------------------------------------------------------------------------------------------------------
                                                               Visibility        Visibility        Visibility
                                                               improvement       improvement       improvement
                                                              (delta dv for     (delta dv for     (delta dv for
                       Class I area                         the maximum 98th  the maximum 98th  the maximum 98th
                                                               percentile        percentile        percentile
                                                            impact) - LNBs +  impact) - LNBs +  impact) - LNBs +
                                                                   OFA            OFA/SNCR           OFA/SCR
----------------------------------------------------------------------------------------------------------------
Badlands..................................................              0.44              0.52              0.67
Mt. Zirkel................................................              0.21              0.25              0.33
Rawah.....................................................              0.24              0.29              0.38
Rocky Mountain............................................              0.34              0.41              0.54
----------------------------------------------------------------------------------------------------------------

    EPA does not agree with the State's conclusion that a limit of 0.28
lb/MMBtu, which can be achieved with the installation and operation of
LNBs with OFA, is reasonable for NOX BART for Dave Johnston
Unit 3. We propose to find that Wyoming did not properly follow the
requirements of the BART Guidelines in determining NOX BART
for this unit. Specifically, we propose to find that Wyoming did not
properly or reasonably conduct certain requirements of the BART
analysis.
    As discussed in detail above, because Wyoming relied on visibility
modeling methodologies that are inconsistent with the statutory and
regulatory requirements, we do not consider Wyoming's analysis of
visibility improvement for the NOX BART to be reasonable for
Dave Johnston Unit 3. We propose to find that Wyoming's analysis for
this Unit is inconsistent with the statutory and regulatory requirement
that ``the degree of improvement in visibility which may reasonably be
anticipated to result from the use of such technology.''
    Also, we are not relying on the State's costs due to reasons stated
in section VII.C.3.a. We propose to find that Wyoming did not properly
or reasonably ``take into consideration the costs of compliance.''
Thus, the State's BART analysis for Dave Johnson Unit 3 does not meet
the requirements of the CAA and the RHR, and we are proposing to
disapprove the analysis and the State's NOX BART
determination. We are proposing a FIP for NOX BART to fill
the gap left by our disapproval, as explained below.
    Our analysis follows our BART Guidelines. With the exception of the
NOX emission limits, the visibility improvement analyses,
and the cost analyses, EPA is proposing to find that the Wyoming
regional haze NOX BART analysis for Dave Johnson Units 3
fulfills all the relevant requirements of CAA Section 169A and the
Regional Haze Rule. As discussed above, Wyoming's visibility
improvement analyses for these units is inconsistent with the
requirements found in the BART Guidelines.
    EPA's NOX BART analysis and the visibility impacts for
Dave Johnson Units 3 are summarized in Tables 46-47 above and detailed
information can be found in the docket.\52\ The cost-effectiveness for
LNB with OFA and SCR at this unit is $2,540, with visibility
improvement at the most impacted Class I area of 1.00 dv. SCR provides
significant visibility improvement at other impacted Class I areas,
with cumulative visibility improvements of 2.92 dv. We do not find that
the incremental cost-effectiveness for LNBs with OFA and SCR precludes
the selection of this technology for BART. The cost-effectiveness and
visibility improvement are within the range that Wyoming in its SIP and
EPA in other SIP and FIP actions have considered reasonable in the BART
context.
---------------------------------------------------------------------------

    \52\ Detailed supporting information for our cost and visibility
improvement analyses can be found in the Docket (see Staudt memos
and EPA BART and RP Modeling for Wyoming, respectively).
---------------------------------------------------------------------------

    Based on our examination of the cost estimates and the predicted
visibility improvement (along with a consideration of the other BART
factors), we propose to find that LNBs with OFA plus SCR at an emission
limit of 0.07 lb/MMBtu (30-day rolling average) is reasonable and
consistent with the CAA and BART Guideline requirements for
NOX BART for Dave Johnston Unit 3. We are proposing that the
FIP NOX BART emission limit for PacifiCorp Dave Johnston
Unit 3 is 0.07 lb/MMBtu (30-day rolling average).
    We propose that PacifiCorp meet our proposed emission limit at Dave
Johnston Unit, as expeditiously as practicable, but no later than five
years after EPA finalizes action on our proposed FIP, consistent with
the requirements of 40 CFR 51.308(e)(iv).
    We are also asking if interested parties have additional
information regarding the BART factors and EPA's proposed
determination, for example our weighing of average costs, incremental
costs, visibility improvement, and timing of installation of such
controls, and in light of such information, whether the interested
parties think the Agency should consider another BART control
technology option that could be finalized either instead of, or in
conjunction with, BART as proposed. The Agency will take the comments
and testimony received, as well as any further SIP revisions submitted
by the State, into consideration in our final promulgation.
Supplemental information received may lead the Agency to adopt final
SIP and/or FIP regulations that reflect a different BART control
technology option, or impact other proposed regulatory provisions,
which differ from this proposal.
Wyoming's NOX BART Determination for Dave Johnston Unit 4
    Unit 4 is currently controlled with LNBs that were placed in
operation in 1976. The State determined new LNBs with advanced OFA, new
LNBs with advanced OFA and SNCR, and new LNBs with advanced OFA and SCR
were technically feasible for controlling NOX emissions for
Unit 4. The State did not identify any technically infeasible controls.
    The State did not identify any energy or non-air quality
environmental impacts that would preclude the selection of any of the
controls evaluated, and there are no remaining-useful-life issues for
this source. Baseline NOX emissions are 8,566 tpy for Unit 4
based on unit heat input rate of 2,500 MMBtu/hr and 7,884 hours of
operation. A summary of the State's NOX BART analysis and
the visibility impacts is provided in Table 48 below. As discussed
above, the visibility improvement modeling results in these tables were
developed by EPA because Wyoming did not properly follow the BART
Guidelines.

                                          Table 48--Summary of Wyoming's Dave Johnston Unit 4 NOX BART Analysis
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Visibility
                                                                                improvement
                                                                                (delta
                                                           Emission rate                                                                   deciview for
                                                            (lb/MMBtu)       Emission                      Average cost     Incremental     the maximum
                   Control technology                         (30-day        reduction      Annualized     effectiveness       cost            98th
                                                              rolling          (tpy)           costs          ($/ton)      effectiveness    percentile
                                                             average)                                                                     impact at Wind
                                                                                Cave National
                                                                                Park) EPA
                                                                                analysis
--------------------------------------------------------------------------------------------------------------------------------------------------------
New LNB with advanced OFA...............................            0.15           6,142        $841,527            $137  ..............            0.71
New LNB with advanced OFA and SNCR......................            0.12           6,626       2,141,786             323          $2,686            0.80
New LNB with advanced OFA and SCR.......................            0.07           7,435      16,430,528           2,210          17,662            0.97
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Based on its consideration of the five factors, the State
determined new LNBs with advanced OFA was reasonable for NOX
BART for Dave Johnston Unit 4. The State determined the NOX
BART emission limit for Unit 4 is 0.15 lb/MMBtu (30-day rolling
average).
EPA's Conclusions on Dave Johnston Unit 4 NOX BART
Determination and FIP for NOX BART
    The EPA agrees with the State's analysis pertaining to energy or
non-air quality environmental impacts and remaining-useful-life for
this source. We disagree with the State's estimate of baseline
NOX emissions (8,566 tpy) because it is based on a unit heat
input rate of 2,500 MMBtu/hr and 7,884 hours of operation rather than
an average of actual annual emissions. EPA finds that baseline
NOX emissions are 5,070 tpy for Unit 4 based on the actual
annual average for the years 2001-2003. A summary of the EPA's
NOX BART analysis and the visibility impacts is provided in
Tables 49 and 50 below.

                                            Table 49--Summary of EPA's Dave Johnston Unit 4 NOX BART Analysis
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Visibility
                                                                                improvement
                                                                                (delta dv for
                                                           Emission rate     Emission                      Average cost     Incremental     the maximum
                   Control technology                       (lb/MMBtu)       reduction      Annualized     effectiveness       cost            98th
                                                              (annual          (tpy)           costs          ($/ton)      effectiveness    percentile
                                                             average)                                                                     impact at Wind
                                                                                Cave National
                                                                                Park)
--------------------------------------------------------------------------------------------------------------------------------------------------------
New LNBs with OFA.......................................            0.14           3,114        $767,342            $246  ..............            0.84
New LNBs with OFA and SNCR..............................            0.11           3,505       2,592,288             740          $4,665            0.95
New LNBs with OFA and SCR...............................            0.05           4,377      13,021,894           2,975          11,951             1.2
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Dave Johnston Unit 4 also impacts other Class I areas. The
visibility improvement EPA modeled at other Class I areas is shown in
Table 50 below.

              Table 50--Dave Johnston Unit 4: Visibility Improvement Modeled at Other Class I Areas
----------------------------------------------------------------------------------------------------------------
                                                               Visibility        Visibility        Visibility
                                                               improvement       improvement       improvement
                                                              (delta dv for     (delta dv for     (delta dv for
                       Class I area                         the maximum 98th  the maximum 98th  the maximum 98th
                                                               percentile        percentile        percentile
                                                              impact) - new     impact) - new     impact) - new
                                                               LNBs + OFA      LNBs + OFA/SNCR   LNBs + OFA/SCR
----------------------------------------------------------------------------------------------------------------
Badlands..................................................              0.54              0.57              0.73
Mt. Zirkel................................................              0.28              0.32              0.37
Rawah.....................................................              0.29              0.32              0.39
Rocky Mountain............................................              0.45              0.51              0.63
----------------------------------------------------------------------------------------------------------------

    EPA does not agree with the State's conclusion that a limit of 0.15
lb/MMBtu, which can be achieved with the installation and operation on
new LNBs with OFA, is reasonable for NOX BART for Dave
Johnston Unit 4. We propose to find that Wyoming did not properly
follow the requirements of the BART Guidelines in determining
NOX BART for this unit. Specifically, we propose to find
that Wyoming did not properly or reasonably conduct certain
requirements of the BART analysis.
    As discussed in detail above, because Wyoming relied on visibility
modeling methodologies that are inconsistent with the statutory and
regulatory requirements, we do not consider Wyoming's analysis of
visibility improvement for the NOX BART to be

reasonable for Dave Johnston Unit 4. We propose to find that Wyoming's
analysis for this Unit is inconsistent with the statutory and
regulatory requirement that ``the degree of improvement in visibility
which may reasonably be anticipated to result from the use of such
technology.''
    Also, we are not relying on the State's costs due to reasons stated
in section VII.C.3.b. We propose to find that Wyoming did not properly
or reasonably ``take into consideration the costs of compliance.''
Thus, the State's BART analysis for Dave Johnson Unit 4 does not meet
the requirements of the regional haze regulation, and we are proposing
to disapprove the analysis and the State's NOX BART
determination. We are proposing a FIP for NOX BART to fill
the gap left by our disapproval, as explained below.
    Our analysis follows our BART Guidelines. With the exception of the
NOX emission limits, the visibility improvement analyses,
and the cost-effectiveness analyses, EPA is proposing to find that the
Wyoming RH BART analysis of NOX for Dave Johnson Units 4
fulfills all the relevant requirements of CAA Section 169A and the RHR.
As discussed above, Wyoming's visibility improvement analyses for these
units are inconsistent with the requirements found in the BART
Guidelines.
    EPA's NOX BART analysis and the visibility impacts for
Dave Johnson Unit 4 are summarized in Tables 49-50 above and detailed
information can be found in the docket.\53\ Additionally, the cost
effectiveness and visibility improvement are within the range that
Wyoming in its SIP and EPA in other SIP and FIP actions have considered
reasonable and consistent with the BART Guidelines.
---------------------------------------------------------------------------

    \53\ Detailed supporting information for our cost and visibility
improvement analyses can be found in the Docket (see Staudt memos
and EPA BART and RP Modeling for Wyoming, respectively).
---------------------------------------------------------------------------

    Based on our examination of the cost estimates and the predicted
visibility improvement (along with a consideration of the other BART
factors), we propose to find that new LNBs with OFA plus SNCR at an
emission limit of 0.12 lb/MMBtu (30-day rolling average) is reasonable
and consistent with the CAA and BART Guideline requirements for
NOX BART for Dave Johnston Unit 4. We are proposing that the
FIP NOX BART emission limit for PacifiCorp Dave Johnston
Unit 4 is 0.12 lb/MMBtu (30-day rolling average).
    We propose to eliminate the higher performing control option (i.e.,
new LNBs with advanced OFA plus SCR) because, although the average cost
effectiveness and visibility improvement for SCR are within the range
EPA has found reasonable in other SIP or FIP actions, we find that the
incremental cost of SCR at $11,951/ton is high enough so that it
precludes the selection of SCR.
    We propose that PacifiCorp meet our proposed emission limit at Dave
Johnston Unit 4, as expeditiously as practicable, but no later than
five years after EPA finalizes action on our proposed FIP. This is
consistent with the requirements of 40 CFR 51.308(e)(iv).
    We are also asking if interested parties have additional
information regarding the BART factors and EPA's proposed
determination, for example our weighing of average costs, incremental
costs, visibility improvement, and timing of installation of such
controls, and in light of such information, whether the interested
parties think the Agency should consider another BART control
technology option that could be finalized either instead of, or in
conjunction with, BART as proposed. The Agency will take the comments
and testimony received, as well as any further SIP revisions submitted
by the State, into consideration in our final promulgation.
Supplemental information received may lead the Agency to adopt final
SIP and/or FIP regulations that reflect a different BART control
technology option, or impact other proposed regulatory provisions,
which differ from this proposal.
3. Proposal in the Alternative for PacifiCorp Jim Bridger Units 1 and 2
NOX BART
    As noted above, EPA is seeking comment on a proposal (``first
proposed approach'') to approve the regional haze plan submitted by the
State for Jim Bridger Unit 1 and Unit 2. EPA also is seeking comment on
another alternative approach (``second proposed approach'') that would
determine that BART for Units 1 and 2 at Jim Bridger power plant is
SCR, and would establish corresponding NOX emission limits
for these units that would have to be achieved within five years of our
final action. This would have the effect of accelerating the
installation of the SCR controls at these units that the State and
source owner (PacifiCorp) had proposed to install later (in the 2021-
2022 time-period). The State determined that BART for these units is
LNB plus OFA, and selected the 2021-2022 time-period for SCR-based
emission limits as a reasonable progress measure. The timeframe was
based on the large number of actions PacifiCorp is undertaking (or
helping to finance) at a large number of EGUs in Wyoming, Utah,
Colorado, and Arizona that it owns and operates or co-owns.
    Under our second proposed approach, EPA would propose that it does
not agree with the State's conclusion that a limit of 0.26 lb/MMBtu is
reasonable for BART for Jim Bridger Units 1 and 2, which can be
achieved with the installation and operation on LNBs with OFA. In
particular, the cost-effectiveness values that EPA calculated for LNBs
with OFA and SCR at Unit 1 is $2,393 with a 0.96 deciview visibility
improvement at the most impacted Class I area. The cost-effectiveness
values that EPA calculated for LNBs with SOFA and SCR at Unit 2 is
$2,492, with a 0.95 deciview visibility improvement at the most
impacted Class I area. Under this approach, EPA would propose to find
that the cost effectiveness values are reasonable and the visibility
improvement significant for LNBs with SOFA plus SCR. In addition, the
costs are within the range that Wyoming in its SIP and EPA in other SIP
and FIP actions have considered reasonable in the BART context. We
would propose in the alternative to find that it was unreasonable for
the State not to determine that LNBs with OFA plus SCR was
NOX BART for Jim Bridger Units 1 and 2. Though the State is
requiring the installation of SCR on Units 1 and 2 under its LTS, the
compliance date for both installations is beyond the five-years allowed
for BART sources by 40 CFR 51.308(e)(iv). Thus, we would propose to
disapprove the State's NOX BART determination for Jim
Bridger Units 1 and 2 and propose a FIP for NOX BART.
    Based on our examination of the cost estimates and the predicted
visibility improvement (along with a consideration of the other BART
factors), for our second proposed approach we would propose to find
that LNBs with SOFA plus SCR at an emission limit of 0.07 lb/MMBtu (30-
day rolling average) is reasonable for NOX BART for Jim
Bridger Units 1 and 2. We would propose that the FIP NOX
BART emission limit for PacifiCorp Units 1 and 2 is 0.07 lb/MMBtu (30-
day rolling average).
    Under our second proposed approach, we would propose that
PacifiCorp meet our proposed emission limit at Jim Bridger Unit 1 and
2, as expeditiously as practicable, but no later than five years after
EPA finalizes action on our proposed FIP. This is consistent with

the requirements of 40 CFR 51.308(e)(iv).\54\
---------------------------------------------------------------------------

    \54\ The proposed regulatory language for this rulemaking only
covers our first proposed approach. If EPA finalizes an action that
differs from our first proposed approach for Jim Bridger Units 1 and
2, we will revise the regulatory language accordingly. If we
finalize action on our first proposed approach, the regulatory
language will reflect a compliance deadline of December 31, 2021 for
Unit 2 and December 31, 2022 for Unit 1. If we finalize action on
our second proposed approach, the regulatory language would be
revised to require compliance at Unit 1 and Unit 2 no later than
five years after we take final action.
---------------------------------------------------------------------------

4. Disapproval of the State's PacifiCorp Naughton Units 1 and 2
NOX BART Determinations and FIP to Address NOX
BART
Wyoming's NOX BART Determination
    During the baseline period of 2001-2003, NOX emissions
from Naughton Unit 1 and Unit 2 were controlled with good combustion
practices with NOX emission limits of 0.75 lb/MMBtu (3-hour
block) per boiler, and 0.58 lb/MMBtu (annual) and 0.54 lb/MMBtu
(annual), respectively. The State determined that new LNBs with OFA,
new LNBs with OFA and SNCR, and new LNBs with OFA and SCR were all
technically feasible for controlling NOX emissions from Unit
1 and Unit 2. The State did not identify any technically infeasible
options.
    The State did not identify any energy or non-air quality
environmental impacts that would preclude the selection of any of the
controls evaluated, and there are no remaining-useful-life issues for
this source. A summary of the State's NOX BART analyses for
Units 1 and 2 is provided in Tables 51 and 52 below. As discussed
above, the visibility improvement modeling results in these tables were
developed by EPA because Wyoming did not properly follow the BART
Guidelines. Baseline NOX emissions are 4,230 tpy for Unit 1
and 5,109 tpy for Unit 2 based on heat input rates of 1,850 MMBtu/hr
and 2,400 MMBtu/hr, respectively, and 7,884 hours of operation.

                                            Table 51--Summary of Wyoming's Naughton Unit 1 NOX BART Analysis
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Visibility
                                                                                improvement
                                                                                (delta
                                                                                deciview for
                                                           Emission rate                                                                   the  maximum
                                                            (lb/MMBtu)       Emission       Annualized     Average cost     Incremental        98th
                   Control technology                         (30-day        reduction         costs       effectiveness       cost         percentile
                                                              rolling          (tpy)                          ($/ton)      effectiveness     impact at
                                                             average)                                                                         Bridger
                                                                                Wilderness
                                                                                Area) EPA
                                                                                Analysis
--------------------------------------------------------------------------------------------------------------------------------------------------------
New LNBs with OFA.......................................            0.26           2,334        $993,248            $426  ..............            0.79
New LNBs with OFA and SNCR..............................            0.21           2,699       1,972,363             731          $2,683            0.80
New LNBs with OFA and SCR...............................            0.07           3,720      10,231,210           2,750           8,089            1.07
--------------------------------------------------------------------------------------------------------------------------------------------------------

                                            Table 52--Summary of Wyoming's Naughton Unit 2 NOX BART Analysis
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Visibility
                                                                                improvement
                                                                                (delta
                                                                                deciview)
                                                                                (delta
                                                           Emission rate                                                                   deciview for
                                                            (lb/MMBtu)       Emission       Annualized     Average cost     Incremental    the  maximum
                   Control technology                         (30-day        reduction         costs       effectiveness       cost            98th
                                                              rolling          (tpy)                          ($/ton)      effectiveness    percentile
                                                             average)                                                                        impact at
                                                                                Bridger
                                                                                Wilderness
                                                                                Area) EPA
                                                                                Analysis
--------------------------------------------------------------------------------------------------------------------------------------------------------
New LNBs with OFA.......................................            0.26           2,649        $945,683            $357  ..............            0.70
New LNBs with OFA and SNCR..............................            0.21           3,122       2,260,957             724          $2,781            0.74
New LNBs with OFA and SCR...............................            0.07           4,447      12,664,919           2,848           7,852            1.10
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Based on its consideration of the five factors, the State
determined new LNBs with OFA was reasonable for NOX BART for
Unit 1 and Unit 2. The State determined SNCR and SCR were not
reasonable based on the high cost effectiveness and associated
visibility improvement. The State determined that the NOX
BART emission limit for Naughton Unit 1 is 0.26 lb/MMBtu (30-day
rolling average), and the NOX BART emission limit for
Naughton Unit 2 is 0.26 lb/MMBtu (30-day rolling average).
EPA's PacifiCorp Naughton Units 1 and 2 NOX BART
Determination and Proposed FIP for NOX BART
    The EPA agrees with the State's analysis pertaining to energy or
non-air quality environmental impacts and remaining-useful-life for
this source. We disagree with the State's estimate of baseline
NOX emissions of 4,230 tpy for Unit 1 and 5,109 tpy for Unit
2 because these estimates are based on heat input rates of 1,850 MMBtu/
hr and 2,400 MMBtu/hr, respectively rather than an average of actual
annual emissions. EPA finds that baseline NOX emissions are
3,553 tpy for Unit 1 and 4,337 tpy for Unit 2 based on the actual
annual average for the years 2001-2003. A summary of the EPA's
NOX BART analysis and the visibility impacts is provided in
Tables 53-56 below.

                                              Table 53--Summary of EPA's Naughton Unit 1 NOX BART Analysis
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Visibility
                                                                                improvement
                                                                                (delta dv for
                                                           Emission rate                                                                    the maximum
                                                            (lb/MMBtu)       Emission       Annualized     Average cost     Incremental        98th
                   Control technology                         (annual        reduction         costs       effectiveness       cost         percentile
                                                             average)          (tpy)                          ($/ton)      effectiveness     impact at
                                                                                Bridger
                                                                                Wilderness
                                                                                Area)
--------------------------------------------------------------------------------------------------------------------------------------------------------
New LNBs with OFA.......................................            0.21           2,100        $932,466            $444  ..............            0.84
New LNBs with OFA and SNCR..............................            0.16           2,463       2,258,826             917          $3,650            0.99
New LNBs with OFA and SCR...............................            0.05           3,209       7,437,269           2,318           6,947            1.23
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Naughton Unit 1 also impacts other Class I areas. The visibility
improvement modeled by EPA at other Class I areas is shown in Table 54
below.

                    Table 54--Naughton Unit 1: Visibility Improvement at Other Class I Areas
----------------------------------------------------------------------------------------------------------------
                                                                                Visibility
                                                                    Visibility      improvement     Visibility
                                                                    improvement    (delta dv for    improvement
                                                                   (delta dv for    the maximum    (delta dv for
                          Class I area                              the maximum        98th         the maximum
                                                                       98th         percentile         98th
                                                                    percentile      impact) new     percentile
                                                                    impact) new     LNBs + OFA/     impact) new
                                                                    LNBs + OFA         SNCR       LNBs + OFA/SCR
----------------------------------------------------------------------------------------------------------------
Fitzpatrick.....................................................            0.38            0.45            0.56
N. Absaroka.....................................................            0.14            0.16            0.20
Washakie........................................................            0.20            0.23            0.29
Teton...........................................................            0.25            0.29            0.36
Grand Teton.....................................................            0.33            0.39            0.49
Yellowstone.....................................................            0.28            0.32            0.41
----------------------------------------------------------------------------------------------------------------

                                              Table 55--Summary of EPA's Naughton Unit 2 NOX BART Analysis
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Visibility
                                                                                improvement
                                                                                (delta dv for
                                                           Emission rate                                                                    the maximum
                                                            (lb/MMBtu)       Emission       Annualized     Average cost     Incremental        98th
                   Control technology                         (annual        reduction         costs       effectiveness       cost         percentile
                                                             average)          (tpy)                          ($/ton)      effectiveness     impact at
                                                                                Bridger
                                                                                Wilderness
                                                                                Area)
--------------------------------------------------------------------------------------------------------------------------------------------------------
New LNBs with OFA.......................................            0.21           2,586        $883,900            $342  ..............            0.97
New LNBs with OFA and SNCR..............................            0.16           3,024       2,510,049             830          $3,713            1.15
New LNBs with OFA and SCR...............................            0.05           3,922       8,843,387           2,255           7,050            1.42
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Naughton Unit 2 also impacts other Class I areas. The visibility
improvement modeled by EPA at other Class I areas is shown in Table 56
below.

                    Table 56--Naughton Unit 2: Visibility Improvement at Other Class I Areas
----------------------------------------------------------------------------------------------------------------
                                                                                Visibility
                                                                    Visibility      improvement     Visibility
                                                                    improvement    (delta dv for    improvement
                                                                   (delta dv for    the maximum    (delta dv for
                          Class I area                              the maximum        98th         the maximum
                                                                       98th         percentile         98th
                                                                    percentile      impact) new     percentile
                                                                    impact) new     LNBs + OFA/     impact) new
                                                                    LNBs + OFA         SNCR       LNBs + OFA/SCR
----------------------------------------------------------------------------------------------------------------
Fitzpatrick.....................................................            0.43            0.51            0.64
N. Absaroka.....................................................            0.18            0.21            0.26
Washakie........................................................            0.24            0.28            0.34
Teton...........................................................            0.24            0.37            0.45
Grand Teton.....................................................            0.48            0.56            0.70

Yellowstone.....................................................            0.26            0.30            0.37
----------------------------------------------------------------------------------------------------------------

    EPA does not agree with the State's conclusion that a limit of 0.26
lb/MMBtu, which can be achieved with the installation and operation of
new LNBs with SOFA, is reasonable for BART for Naughton Units 1 and 2.
We propose to find that Wyoming did not properly follow the
requirements of the BART Guidelines in determining NOx BART for these
units. Specifically, we propose to find that Wyoming did not properly
or reasonably conduct certain requirements of the BART analyses.
    As discussed in detail above, because Wyoming relied on visibility
modeling methodologies that are inconsistent with the statutory and
regulatory requirements, we do not consider Wyoming's analysis of
visibility improvement for the NOX BART to be reasonable for
Naughton Units 1 and 2. We propose to find that Wyoming's analyses for
these Units are inconsistent with the statutory and regulatory
requirement that ``the degree of improvement in visibility which may
reasonably be anticipated to result from the use of such technology.''
    Also, we are not relying on the State's costs due to reasons stated
in section VII.C.3.b. We propose to find that Wyoming did not properly
or reasonably ``take into consideration the costs of compliance.''
Thus, the State's BART analyses for Naughton Units 1 and 2 do not meet
the requirements of the CAA and RHR, and we are proposing to disapprove
the analyses and the State's NOX BART determinations. We are
proposing a FIP for NOX BART to fill the gaps left by our
disapproval, as explained below.
    Our analysis follows our BART Guidelines. With the exception of the
NOX emission limits, the visibility improvement analyses,
and the cost effectiveness analyses, EPA is proposing to find that the
Wyoming's regional haze NOX BART analysis for Naughton Units
1 and 2, fulfills all the relevant requirements of CAA Section 169A and
the RHR.
    EPA's NOX BART analysis and the visibility impacts for
Naughton Units 1 and 2 are summarized in Tables 53-56 above and
detailed information can be found in the docket.\55\ EPA's cost
analysis estimated the cost-effectiveness value for LNBs with OFA and
SCR at Unit 1 is $2,318/ton with a 1.23 dv visibility improvement at
the most impacted Class I area. The cost effectiveness value for LNBs
with OFA and SCR at Unit 2 is estimated at $2,255/ton, with a 1.42 dv
visibility improvement at the most impacted Class I area. In addition,
the installation of SCR will also have substantial visibility benefits
for other Class I areas, besides the most impacted area. The cumulative
visibility improvement is 3.54 dv for Unit 1 and 4.18 dv for Unit 2.
EPA followed the BART Guidelines in developing these cost-effectiveness
values, which are reasonable and the visibility improvement is
significant for new LNBs with OFA plus SCR. The costs and visibility
improvements are within the range that Wyoming in its SIP and EPA in
other SIP and FIP actions have considered reasonable in the BART
context.
---------------------------------------------------------------------------

    \55\ Detailed supporting information for our cost and visibility
improvement analyses can be found in the Docket (see Staudt memos
and EPA BART and RP Modeling for Wyoming, respectively).
---------------------------------------------------------------------------

    Based on our examination of the cost estimates and the predicted
visibility improvement (along with a consideration of the other BART
factors), we propose to find that new LNBs with OFA plus SCR at an
emission limit of 0.07 lb/MMBtu (30-day rolling average) is reasonable
and consistent with the CAA and BART Guidelines requirements for
NOX BART for Naughton Units 1 and 2. We are proposing that
the FIP NOX BART emission limit for PacifiCorp Naughton
Units 1 and 2 is 0.07 lb/MMBtu (30-day rolling average).
    We propose that PacifiCorp meet our proposed emission limit at
Naughton Unit 1 and 2, as expeditiously as practicable, but no later
than five years after EPA finalizes action on our proposed FIP. This is
consistent with the requirements of 40 CFR 51.308(e)(iv).
    We are also asking if interested parties have additional
information regarding the BART factors and EPA's proposed
determination, for example our weighing of average costs, incremental
costs, visibility improvement, and timing of installation of such
controls, and in light of such information, whether the interested
parties think the Agency should consider another BART control
technology option that could be finalized either instead of, or in
conjunction with, BART as proposed. The Agency will take the comments
and testimony received, as well as any further SIP revisions submitted
by the State, into consideration in our final promulgation.
Supplemental information received may lead the Agency to adopt final
SIP and/or FIP regulations that reflect a different BART control
technology option, or impact other proposed regulatory provisions,
which differ from this proposal.
5. Disapproval of the State's PacifiCorp Wyodak Unit 1 NOX
BART Determination and FIP To Address NOX BART
Wyoming's NOX BART Determination
    During the baseline period, Wyodak Unit 1 was controlled for
NOX emissions with early generation LNBs with emission
limits of 0.70 lb/MMBtu (3-hour block) and 0.31 lb/MMbtu (annual). The
State determined new LNBs with OFA, existing LNBs with ROFA, new LNBs
with OFA plus SNCR, and new LNBs with OFA plus SCR were technically
feasible for controlling NOX emissions. The State did not
identify any technically infeasible control options.
    The State did not identify any energy or non-air quality
environmental impacts that would preclude the selection of any of the
controls evaluated, and there are no remaining-useful-life issues for
this source. A summary of the State's NOX BART analyses for
Unit 1 is provided in Table 57 below. Baseline NOX emissions
are 5,744 tpy based on the unit heat input rate of 4,700 MMBtu/hr and
7,884 hours of operation per year. As discussed above, the visibility
improvement modeling results in these tables were developed by EPA
because Wyoming

did not properly follow the BART Guidelines.

                                             Table 57--Summary of Wyoming's Wyodak Unit 1 NOX BART Analysis
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Visibility
                                                                                improvement
                                                                                (delta dv for
                                                           Emission rate                                                                    the maximum
                                                            (lb/MMBtu)       Emission       Annualized     Average cost     Incremental        98th
                   Control technology                         (30-day        reduction         costs       effectiveness       cost         percentile
                                                              rolling          (tpy)                          ($/ton)      effectiveness  impact at Wind
                                                             average)                                                                      Cave National
                                                                                Park)  EPA
                                                                                analysis
--------------------------------------------------------------------------------------------------------------------------------------------------------
LNBs with OFA...........................................            0.23           1,483      $1,306,203            $881  ..............            0.25
LNBs with OFA and SNCR..................................            0.18           2,409       2,306,728             958          $1,080            0.40
LNBs with OFA and SCR...................................            0.07           4,447      18,910,781           4,252           8,147            0.72
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Based on its consideration of the five factors, the State
determined LNBs with OFA was reasonable for NOX BART for
Unit 1. The State determined other control technologies were not
reasonable based on the high-cost effectiveness values and low
visibility improvement. The State determined the NOX BART
emission limit for Wyodak Unit 1 is 0.23 lb/MMBtu (30-day rolling
average).
EPA's Conclusions on Wyodak Unit 1 NOX BART Determination
and FIP for NOX BART
    The EPA agrees with the State's analysis pertaining to energy or
non-air quality environmental impacts and remaining-useful-life for
this source. We disagree with the State's estimate of baseline
NOX emissions of 5,744 tpy because these estimates are based
on the unit heat input rate of 4,700 MMBtu/hr and 7,884 hours of
operation per year rather than an average of actual annual emissions.
EPA finds that baseline NOX emissions are 4,615 tpy based on
the actual annual average for the years 2001-2003. A summary of the
EPA's NOX BART analysis and the visibility impacts is
provided in Tables 58 and 59 below.

                                                  Table 58--Summary of EPA's Wyodak's NOX BART Analysis
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Visibility
                                                                                improvement
                                                                                (delta dv for
                                                           Emission rate     Emission                      Average cost     Incremental     the maximum
                   Control technology                       (lb/MMBtu)       reduction      Annualized     effectiveness       cost            98th
                                                              (annual          (tpy)           costs          ($/ton)      effectiveness    percentile
                                                             average)                                                                     impact at Wind
                                                                                Cave National
                                                                                Park)
--------------------------------------------------------------------------------------------------------------------------------------------------------
New LNBs with OFA.......................................            0.19           1,239      $1,272,427          $1,027  ..............            0.24
New LNBs with OFA and SNCR..............................            0.15           1,914       3,787,466           1,979          $3,725            0.38
New LNBs with OFA and SCR...............................            0.05           3,735      14,386,417           3,852           5,822            0.71
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Wyodak also impacts one other Class I area. The visibility
improvement EPA modeled at the other Class I area is shown in Table 59
below.

                         Table 59--Wyodak: Visibility Improvement at Other Class I Areas
----------------------------------------------------------------------------------------------------------------
                                                                                Visibility
                                                                    Visibility      improvement     Visibility
                                                                    improvement    (delta dv for    improvement
                                                                   (delta dv for    the maximum    (delta dv for
                          Class I area                              the maximum        98th         the maximum
                                                                       98th         percentile         98th
                                                                    percentile     impact) - new    percentile
                                                                   impact) - new    LNBs + OFA/    impact) - new
                                                                    LNBs + OFA         SNCR       LNBs + OFA/SCR
----------------------------------------------------------------------------------------------------------------
Badlands........................................................            0.17            0.23            0.45
----------------------------------------------------------------------------------------------------------------

    EPA does not agree with the State's conclusion that a limit of 0.23
lb/MMBtu is reasonable for NOX BART for Wyodak Unit 1, which
can be achieved with the installation and operation of new LNBs with
OFA. We propose to find that Wyoming did not properly follow the
requirements of the BART Guidelines in determining NOx BART for this
unit. Specifically, we propose to find that Wyoming did not properly or
reasonably conduct certain requirements of the BART analysis.
    As discussed in detail above, because Wyoming relied on visibility
modeling methodologies that are inconsistent with the statutory and
regulatory requirements, we do not consider Wyoming's analysis of
visibility improvement for the NOX BART to be reasonable for
Wyodak Unit 1. We propose to find that Wyoming's analysis for this Unit
is inconsistent with the statutory and regulatory requirement that
``the degree of improvement in visibility which may reasonably be

anticipated to result from the use of such technology.''
    Also, we are not relying on the State's costs due to reasons stated
in section VII.C.3.b of this notice. We propose to find that Wyoming
did not properly or reasonably ``take into consideration the costs of
compliance.'' Thus, the State's BART analysis for Wyodak Unit 1 does
not meet the requirements of the CAA and RHR, and we are proposing to
disapprove the analysis and the State's NOX BART
determination. We are proposing a FIP for NOX BART to fill
the gap left by our disapproval, as explained below.
    Our analysis follows our BART Guidelines. With the exception of the
NOX emission limits, the visibility improvement analyses,
and the cost-effectiveness analyses, EPA is proposing to find that the
Wyoming's regional haze NOX BART analysis for Wyodak Unit 1
fulfills all the relevant requirements of CAA Section 169A and the RHR.
    EPA's NOX BART analysis and the visibility impacts for
Wyodak Unit 1 are summarized in Tables 58-59 above and detailed
information can be found in the docket.\56\ In particular, the cost
effectiveness value for new LNB with OFA plus SNCR at this unit is
$1,979/ton with a visibility improvement at the most impacted Class I
area of 0.38 deciviews. The costs are within the range that EPA in
other SIP and FIP actions has considered reasonable and consistent with
the BART Guidelines.
---------------------------------------------------------------------------

    \56\ Detailed supporting information for our cost and visibility
improvement analyses can be found in the Docket (see Staudt memos
and EPA BART and RP Modeling for Wyoming, respectively.
---------------------------------------------------------------------------

    Based on our examination of the costs estimates, emission
reductions, and the predicted visibility improvement, we propose to
find that new LNBs with OFA plus SNCR at an emission limit of 0.17 lb/
MMBtu (30-day rolling average) is reasonable and consistent with the
CAA and BART Guideline requirements for NOX BART for Wyodak
Unit 1. We are proposing that the FIP NOX BART emission
limit for PacifiCorp Wyodak Unit 1 is 0.17 lb/MMBtu (30-day rolling
average).
    We have eliminated the highest performing option from
consideration--new LNBs with OFA plus SCR. Although the cost-
effectiveness and visibility improvement are within the range of other
EPA FIP actions, we find that the cumulative visibility improvement of
1.16 deciviews for new LNBs with OFA plus SCR is low compared to the
cumulative visibility benefits that will be achieved by requiring SCR
at Dave Johnston Unit 3 (2.92 dv), Laramie River Unit 1 (2.12 dv),
Laramie River Unit 2 (1.97 dv), Laramie River Unit 3 (2.29 dv),
Naughton Unit 1 (3.54 dv), and Naughton Unit 2 (4.18 dv).
    We propose that PacifiCorp meet our proposed emission limit at
Wyodak Unit 1, as expeditiously as practicable, but no later than five
years after EPA finalizes action on our proposed FIP. This is
consistent with the requirements of 40 CFR 51.308(e)(iv).
    We are also asking if interested parties have additional
information regarding the BART factors and EPA's proposed
determination, for example our weighing of average costs, incremental
costs, visibility improvement, and timing of installation of such
controls, and in light of such information, whether the interested
parties think the Agency should consider another BART control
technology option that could be finalized either instead of, or in
conjunction with, BART as proposed. The Agency will take the comments
and testimony received, as well as any further SIP revisions submitted
by the State, into consideration in our final promulgation.
Supplemental information received may lead the Agency to adopt final
SIP and/or FIP regulations that reflect a different BART control
technology option, or impact other proposed regulatory provisions,
which differ from this proposal.

B. Disapproval of the State's NOX Reasonable Progress
Determinations and Federal Implementation Plan for NOX
Reasonable Progress Determinations and Limits

    We are proposing to disapprove the State's reasonable progress
determination for PacifiCorp Dave Johnston Unit 1 and Unit 2, and we
are proposing a reasonable progress NOX FIP for these units,
as explained below. As noted above, the State provided four-factor
analyses that evaluated the required factors. However, due to
deficiencies in the control cost estimates, EPA conducted its own cost
analyses for Dave Johnston Unit 1 and 2. The cost analysis was done in
the same manner as described for BART sources in Section VII.C.
    We concluded that it is also appropriate to consider a fifth factor
for these units for evaluating potential reasonable progress control
options--the degree of visibility improvement that may reasonably be
anticipated from the use of the reasonable progress controls. Our
reasonable progress guidance contemplates that states (or EPA in lieu
of a state) may be able to consider other relevant factors for
reasonable progress sources (see EPA's Guidance for Setting Reasonable
Progress Goals under the Regional Haze Program, (``Reasonable Progress
Guidance''), pp. 2-3, July 1, 2007). We find it appropriate, in certain
circumstances, to consider visibility improvement when evaluating
potential reasonable progress controls. Thus, in the same manner as
described for BART sources in Section VII.C, EPA conducted visibility
improvement modeling for Dave Johnston Units 1 and 2.
1. PacifiCorp Dave Johnston--Units 1 and 2
Background
    PacifiCorp's Dave Johnston power plant is comprised of four units
burning pulverized subbituminous Powder River Basin coal. Units 3 and 4
are subject to BART, as described above. Units 1 and 2 are nominal 106
MW dry bottom wall-fired boilers. Unit 1 began operation in 1958 and
Unit 2 in 1960.
Wyoming's NOX Reasonable Progress Determinations
    Unit 1 and Unit 2 are currently uncontrolled for NOX
emissions. The State determined that LNBs, LNBs with OFA, SNCR, and SCR
were technically feasible for controlling NOX emissions. The
State did not identify any technically infeasible control options.
    The State did not identify any energy or non-air quality
environmental impacts that would preclude the selection of any of the
controls evaluated, and there are no remaining-useful-life issues for
this source. A summary of the State's NOX reasonable
progress analyses for Unit 1 and Unit 2, along with our visibility
modeling results, are provided in Tables 60 and 61 below. Baseline
NOX emissions are 2,256 tpy for Unit 1 and 2,174 tpy for
Unit 2 based on 2002 actual emissions. Wyoming did not provide
controlled emission rates in their reasonable progress analysis.

                   Table 60--Summary of Dave Johnston Unit 1 NOX Reasonable Progress Analysis
----------------------------------------------------------------------------------------------------------------
                                                                                Visibility
                                                                                improvement
                                                                                (delta dv for
                                                                                the maximum
                                      Control        Emission       Annualized     Average cost        98th
       Control technology         efficiency (%)     reduction         costs       effectiveness    percentile
                                                       (tpy)                          ($/ton)     impact at Wind
                                                                                Cave National
                                                                                Park) EPA
                                                                                Analysis
----------------------------------------------------------------------------------------------------------------
LNBs............................              51           1,150        $631,000            $528            0.37
LNBs with OFA...................              65           1,466         962,000             632            0.49
SNCR............................              40             902       2,490,000           2,659            0.26
SCR.............................              80           1,804       3,390,000           1,810            0.58
----------------------------------------------------------------------------------------------------------------

                   Table 61--Summary of Dave Johnston Unit 2 NOX Reasonable Progress Analysis
----------------------------------------------------------------------------------------------------------------
                                                                                Visibility
                                                                                improvement
                                                                                (delta dv for
                                                                                the maximum
                                      Control        Emission       Annualized     Average cost        98th
       Control technology         efficiency (%)     reduction         costs       effectiveness    percentile
                                                       (tpy)                          ($/ton)     impact at Wind
                                                                                Cave National
                                                                                Park) EPA
                                                                                Analysis
----------------------------------------------------------------------------------------------------------------
LNBs............................              51           1,108        $631,000            $538            0.38
LNBs with OFA...................              65           1,413         962,000             644            0.49
SNCR............................              40             869       2,490,000           2,709            0.28
SCR.............................              80           1,739       3,390,000           1,844            0.58
----------------------------------------------------------------------------------------------------------------

    The State estimated that it would take nearly five and a half years
for NOX reduction strategies to become effective. The State
determined that roughly two years would be necessary for the State to
develop the necessary regulations to implement the selected control
measures. The State estimated that it would take up to a year for the
source to secure the capital necessary to purchase emission control
devices and approximately 18 months would be required for the company
to design, fabricate, and install SCR or SNCR technology. Because there
are two boilers being evaluated at Dave Johnston, the State determined
an additional year may be required for staging the installation
process.
    The State determined that no controls were reasonable for this
planning period. The State cited that the four-factor analysis was
limited, in that no guidance was provided by EPA for identifying
significant sources and EPA did not establish contribution to
visibility impairment thresholds (a potential fifth factor for
reasonable progress determinations).\57\ The State further claims that
the State cannot, per Wyoming Statute 35-11-202, establish emission
control requirements except through state rule or regulation.
Furthermore, the Wyoming statute requires the State to consider the
character and degree of injury of the emissions involved. In this case,
the State claims it would need to have visibility modeling that
assessed the degree of injury caused by the emissions, which the State
does not have. The State believes it has taken a strong and reasonable
first step in identifying potential contributors to visibility
impairment, and that the next step of creating an appropriate rule or
regulation will be accomplished in the next SIP revision.
---------------------------------------------------------------------------

    \57\ States must consider the four factors as listed above but
can also take into account other relevant factors for the reasonable
progress sources identified (see EPA's Guidance for Setting
Reasonable Progress Goals under the Regional Haze Program, (``EPA's
Reasonable Progress Guidance''), p. 2-3, July 1, 2007).
---------------------------------------------------------------------------

EPA's Conclusions on Dave Johnston Units 1 and 2 NOX
Reasonable Progress Determination and FIP for NOX Reasonable
Progress Controls
    The EPA agrees with the State's analysis pertaining to energy or
non-air quality environmental impacts and remaining-useful-life for
this source. We disagree with the State's estimate of baseline
NOX emissions of 2,256 tpy for Unit 1 and 2,174 tpy for Unit
2, which were based on 2002 actual emissions. EPA's estimate of
baseline NOX emissions are 2,188 tpy for Unit 1 and 2,161
tpy for Unit 2 based on the actual annual average for the years 2001-
2003. A summary of the EPA's NOX BART analysis and the
visibility impacts is provided in Tables 62-65 below.

                                    Table 62--Summary of EPA's Dave Johnston Unit 1 NOX Reasonable Progress Analysis
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Visibility
                                                                                improvement
                                                                                (delta dv for
                                                           Emission rate     Emission                      Average cost     Incremental     the maximum
                   Control technology                       (lb/MMBtu)       reduction      Annualized     effectiveness       cost            98th
                                                              (annual          (tpy)           costs          ($/ton)      effectiveness    percentile
                                                             average)                                                                     impact at Wind
                                                                                Cave National
                                                                                Park)
--------------------------------------------------------------------------------------------------------------------------------------------------------
LNBs with OFA...........................................            0.20           1,226      $1,187,179            $968  ..............            0.31
LNBs with OFA and SNCR..................................            0.15           1,466       2,087,189           1,423          $3,743            0.35
LNBs with OFA and SCR...................................            0.05           1,947       6,417,536           3,296           9,004            0.44
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Dave Johnston Unit 1 also impacts other Class I areas. The
visibility improvement EPA modeled at other Class I areas is shown in
Table 63 below.

                         Table 63--Visibility Improvement Modeled at Other Class I Areas
----------------------------------------------------------------------------------------------------------------
                                                               Visibility        Visibility        Visibility
                                                               improvement       improvement       improvement
                                                              (delta dv for     (delta dv for     (delta dv for
                       Class I area                         the maximum 98th  the maximum 98th  the maximum 98th
                                                               percentile        percentile        percentile
                                                            impact) - LNBs +  impact) - LNBs +  impact) - LNBs +
                                                                   OFA            OFA/SNCR           OFA/SCR
----------------------------------------------------------------------------------------------------------------
Badlands..................................................              0.17              0.16              0.25
Mt. Zirkel................................................              0.06              0.08              0.13
Rawah.....................................................              0.10              0.12              0.15
Rocky Mountain............................................              0.13              0.16              0.22
----------------------------------------------------------------------------------------------------------------

                                    Table 64--Summary of EPA's Dave Johnston Unit 2 NOX Reasonable Progress Analysis
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Visibility
                                                                                improvement
                                                                                (delta dv for
                                                           Emission rate     Emission                      Average cost     Incremental     the maximum
                   Control technology                       (lb/MMBtu)       reduction      Annualized     effectiveness       cost            98th
                                                              (annual          (tpy)           costs          ($/ton)      effectiveness    percentile
                                                             average)                                                                     impact at Wind
                                                                                Cave National
                                                                                Park)
--------------------------------------------------------------------------------------------------------------------------------------------------------
LNBs with OFA...........................................            0.20           1,180      $1,188,797          $1,007  ..............            0.29
LNBs with OFA and SNCR..................................            0.15           1,425       2,100,619           1,474          $3,718            0.33
LNBs with OFA and SCR...................................            0.05           1,916       6,432,035           3,357           8,830            0.42
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Dave Johnston Unit 1 also impacts other Class I areas. The
visibility improvement EPA modeled at other Class I areas is shown in
Table 65 below.

                         Table 65--Visibility Improvement Modeled at Other Class I Areas
----------------------------------------------------------------------------------------------------------------
                                                               Visibility        Visibility        Visibility
                                                               improvement       improvement       improvement
                                                              (delta dv for     (delta dv for     (delta dv for
                       Class I area                         the maximum 98th  the maximum 98th  the maximum 98th
                                                               percentile        percentile        percentile
                                                            impact) - LNBs +  impact) - LNBs +  impact) - LNBs +
                                                                   OFA            OFA/SNCR           OFA/SCR
----------------------------------------------------------------------------------------------------------------
Badlands..................................................              0.14              0.17              0.24
Mt. Zirkel................................................              0.06              0.09              0.12
Rawah.....................................................              0.09              0.11              0.15
Rocky Mountain............................................              0.13              0.16              0.21
----------------------------------------------------------------------------------------------------------------

    We disagree with the State's reasoning for not adopting reasonable
progress controls for Dave Johnston Unit 1 and Unit 2. If the State
determined that it needed to adopt a rule or perform modeling to
adequately assess and, if warranted, require reasonable progress
controls, the State should have completed these steps before it
submitted its regional haze SIP. The RHR does not allow for commitments
to potentially implement strategies at some later date that are
identified under reasonable progress or for the State to take credit
for such commitments.

    In addition, the cost effectiveness value for LNBs with OFA at Unit
1 is $968/ton and $1,007/ton at Unit 2. These values are very
reasonable and far less than some of the cost effectiveness values the
State found reasonable in making its BART determinations. Given
predicted visibility improvement of approximately 0.30 deciviews per
unit at the most impacted Class I area and the fact that Wyoming's
reasonable progress goals will not meet the URP, we find that it was
unreasonable for the State to reject these very inexpensive controls.
Thus, we are proposing to disapprove the State's NOX
reasonable progress determination for Dave Johnston Unit 1 and Unit 2
and proposing a FIP for NOX reasonable progress controls as
explained below.
    Based on our examination of the State's costs estimates, emission
reductions, and the predicted visibility improvement, we propose to
find that LNBs with OFA at an emission limit of 0.22 lb/MMBtu (30-day
rolling average) is reasonable for NOX reasonable progress
controls for Dave Johnston Units 1 and 2. We are proposing that the FIP
NOX reasonable progress emission limit for PacifiCorp Dave
Johnston Unit 1 and Unit 2 is 0.22 lb/MMBtu (30-day rolling average).
    We propose that PacifiCorp meet our proposed emission limit at Dave
Johnston Units 1 and 2 as expeditiously as practicable, but no later
than July 31, 2018. This is consistent with the requirement that the
SIP cover an initial planning period that ends July 31, 2018.

C. Reasonable Progress Goals

    We are proposing to impose reasonable progress controls on Dave
Johnston Units 1 and 2, as well as more stringent NOX BART
controls on PacifiCorp Dave Johnston Unit 3 and Unit 4, PacifiCorp
Naughton Unit 1 and Unit 2, PacifiCorp Wyodak Unit 1, and Basin
Electric Laramie River Units 1, 2, and 3, than WRAP assumed in modeling
Wyoming's RPGs.
    We could not re-run the WRAP modeling due to time and resource
constraints, but anticipate that the additional controls would result
in an increase in visibility improvement during the 20% worst days. As
noted in our analyses, many of our proposed controls would result in
significant incremental visibility benefits when modeled against
natural background. We anticipate that this would translate into
measurable improvement if modeled on the 20% best days as well. While
we expect our proposed controls will result in additional visibility
improvement, we do not expect that these improvements will result in
the State achieving the URP. For some of the reasons discussed in
section VII.D.3, in particular, emissions from sources outside the WRAP
modeling domain, along with our consideration of the statutory
reasonable progress factors, we find it reasonable for the State to not
achieve the URP during this planning period. We expect the State to
quantify the visibility improvement in its next regional haze SIP
revision.
    For purposes of this action, we are proposing RPGs that are
consistent with the additional controls we are proposing. While we
would prefer to quantify the RPGs, we note that the RPGs themselves are
not enforceable values. The more critical elements for our FIP are the
emissions limits we are proposing to impose, which will be enforceable.

D. Federal Monitoring, Recordkeeping, and Reporting Requirements

    The CAA requires that SIPs, including the regional haze SIP,
contain elements sufficient to ensure emission limits are practically
enforceable.\58\ Other applicable regulatory provisions are contained
in Appendix V to Part 51--Criteria for Determining the Completeness of
Plan Submissions.\59\ We are proposing to find that the State's
regional haze SIP does not contain adequate monitoring, recordkeeping
and reporting requirements. Chapter 6.4, Section V of the SIP contains
monitoring and reporting requirements that we find inadequate for
numerous reasons, summarized as follows: (1) The State's language
includes references to WAQSR Chapters that EPA has not approved as part
of the SIP and are thus not federally enforceable. These references
should be to the appropriate sections in the CFR; (2) Definitions have
not been included; (3) The State's language allows for data
substitution pursuant to 40 CFR part 75. The data substitution
procedures of 40 CFR part 75 were never intended to apply to BART
sources; (4) There are numerous language clarifications and rewordings
needed; and (5) The State did not include appropriate recordkeeping
language.\60\
---------------------------------------------------------------------------

    \58\ CAA Section 110(a)(2) states that SIPs ``shall (A) include
enforceable emission limitations and other control measures, means,
or techniques (including economic incentives such as fees,
marketable permits, and auctions of emissions rights), as well as
schedules and timetables for compliance, as may be necessary or
appropriate to meet the applicable requirements of this chapter; (C)
include a program to provide for the enforcement of the measures
described in subparagraph (A), and regulation of the modification
and construction of any stationary source within the areas covered
by the plan as necessary to assure that national ambient air quality
standards are achieved, including a permit program as required in
parts C and D of this subchapter; (F) require, as may be prescribed
by the Administrator--(i) the installation, maintenance, and
replacement of equipment, and the implementation of other necessary
steps, by owners or operators of stationary sources to monitor
emissions from such sources, (ii) periodic reports on the nature and
amounts of emissions and emissions-related data from such sources,