Class I area                          ([Delta]dv)      SNCR ([Delta]dv)   SCR ([Delta]dv)
----------------------------------------------------------------------------------------------------------------
Arches NP..............................................              0.737              0.906              1.342
Black Canyon of the Gunnison NP........................              0.198              0.241              0.345
Bryce Canyon NP........................................              0.306              0.372              0.534
Canyonlands NP.........................................              0.846              1.041              1.545
Capitol Reef NP........................................              0.639              0.750              1.113
Flat Tops WA...........................................              0.231              0.280              0.404
Grand Canyon NP........................................              0.349              0.426              0.618
Mesa Verde NP..........................................              0.235              0.286              0.426
Zion NP................................................              0.184              0.224              0.323
----------------------------------------------------------------------------------------------------------------

                             Table 16--Hunter Unit 1--Days Greater Than 0.5 Deciview
                                               [Three year total]
----------------------------------------------------------------------------------------------------------------
                                                           LNB with SOFA    LNB with SOFA and  LNB with SOFA and
            Class I area               Baseline (days)         (days)          SNCR (days)         SCR (days)
----------------------------------------------------------------------------------------------------------------
Arches NP...........................                293                260                259                235
Black Canyon of the Gunnison NP.....                 68                 55                 53                 41
Bryce Canyon NP.....................                 42                 37                 36                 28
Canyonlands NP......................                359                330                322                311
Capitol Reef NP.....................                175                160                156                145
Flat Tops WA........................                 77                 63                 59                 50
Grand Canyon NP.....................                 49                 43                 42                 37
Mesa Verde NP.......................                 82                 66                 63                 55
Zion NP.............................                 29                 23                 23                 22
----------------------------------------------------------------------------------------------------------------

                             Table 17--Hunter Unit 1--Days Greater Than 1.0 Deciview
                                               [Three year total]
----------------------------------------------------------------------------------------------------------------
                                                           LNB with SOFA    LNB with SOFA and  LNB with SOFA and
            Class I area               Baseline (days)         (days)          SNCR (days)         SCR (days)
----------------------------------------------------------------------------------------------------------------
Arches NP...........................                170                141                139                122
Black Canyon of the Gunnison NP.....                 22                 13                 12                  9
Bryce Canyon NP.....................                 22                 19                 18                 16
Canyonlands NP......................                240                218                202                188
Capitol Reef NP.....................                118                110                109                 94
Flat Tops WA........................                 31                 20                 18                 10
Grand Canyon NP.....................                 32                 25                 23                 18
Mesa Verde NP.......................                 32                 20                 19                 13
Zion NP.............................                 14                  9                  8                  7
----------------------------------------------------------------------------------------------------------------

    Select BART.
    A summary of our impacts analysis for Hunter Unit 1 is presented in
Table 18.

                                                   Table 18--Summary of Hunter Unit 1 Impacts Analysis
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                          Annual                 Total                                                      Visibility impacts *
                                         emission   Emission    annual     Average cost       Incremental cost     -------------------------------------
            Control option              rate  (lb/ reduction     costs     effectiveness    effectiveness ($/ton)     Improvement     Days >     Days >
                                          MMBtu)     (tpy)    (million$)      ($/ton)                                    (dv)         0.5 dv     1.0 dv
--------------------------------------------------------------------------------------------------------------------------------------------------------
LNB with SOFA.........................       0.21      3,042       $1.2M            $382  ........................           0.846        330        218
LNB with SOFA and SNCR................       0.16      3,735        3.8M           1,016  $3,796..................           1.041        322        202
LNB with SOFA and SCR.................       0.05      5,500       13.1M           2,380  $5,268 (compared to LNB            1.545        311        188
                                                                                with SOFA and SNCR).
                                                                                $4,853 (compared to LNB
                                                                                with SOFA)..
--------------------------------------------------------------------------------------------------------------------------------------------------------
* At the most impacted Class I area, Canyonlands National Park.

    In determining what to co-propose as BART, we have taken into
consideration all five of the statutory factors required by the CAA:
The costs of compliance, the energy and non-air quality environmental
impacts of compliance, any existing pollution control technology in use
at the source, the remaining useful life of the source, and the degree
of improvement in visibility which may reasonably be anticipated to
result from the use of such technology. Later we provide a
justification for our selection of BART, including an explanation of
how each of the CAA factors was used in that selection.
    As described in step 1 before, we have considered the existing
pollution control technology in use at the source. We note that Hunter
Unit 1 was equipped with LNB and SOFA in the spring of 2014 in order to
meet state-law requirements in the 2011 Utah RH SIP submittal, which we
did not approve. In this co-proposal we have to evaluate control
technologies and baseline emissions from the correct starting point,
that is, prior to the installation of the combustion controls pursuant
to state-law NOX limitations.\189\ As a result, we used the
period 2001-2003 as the appropriate period for baseline emissions, in
order to provide a realistic depiction of annual emissions for Hunter
Unit 1 prior to installation of combustion controls.
---------------------------------------------------------------------------

    \189\ See 79 FR 5032, 5105 (Jan. 30, 2014).
---------------------------------------------------------------------------

    We have considered the energy and non-air quality environmental
impacts of compliance and propose to find that

they do not appreciably favor one control option over another, or
preclude a particular control option from selection. And finally, we
have considered the remaining useful life of the source and find that
it is sufficiently long (greater than 20 years) so as not to favor or
preclude any of the control options. As a result, the remaining
factors--the costs of compliance and visibility improvement--are the
primary factors that lead us to our proposed BART selection for Hunter
Unit 1.
    In order to select BART we propose to consider the costs of
compliance and visibility impacts by generally comparing them with BART
determinations that have been made elsewhere. In the context of
reasonable progress determinations, a comparison with another
reasonable progress determination has been upheld by the Ninth Circuit
Court of Appeals as a rational explanation for that determination.\190\
If this were the first BART determination under the RHR and BART
Guidelines, which it is not, it would obviously be difficult to employ
this precise methodology.\191\ At this point, however, the EPA thinks
there are sufficient examples of reasonable determinations to make this
methodology feasible.
---------------------------------------------------------------------------

    \190\ Nat'l Parks Conserv. Ass'n v. U.S. EPA, 788 F.3d 1134,
1148-49 (9th Cir. 2014).
    \191\ Even in that initial scenario, at least cost of
compliance, as expressed in cost-effectiveness in dollars per ton,
can be compared with what has been found reasonable for best
available control technology (BACT) and reasonably available control
technology (RACT), and visibility improvement can be compared with
the 0.5 dv subject-to-BART threshold that determines whether a BART-
eligible source causes or contributes to visibility impairment in
Class I areas. The EPA notes that this alternate methodology would
also support our proposed BART determinations in this action.
---------------------------------------------------------------------------

    Specifically, we propose to compare the average cost-effectiveness,
incremental cost-effectiveness, visibility improvement, and incremental
visibility improvement for LNB and SOFA with SCR with BART
determinations where the EPA and States have based their determination
on the same metrics. The most comparable determination appears to be in
EPA's final action for Wyoming's regional haze SIP, in which EPA
promulgated a FIP for three units at Laramie River Station and
determined NOX BART to be LNB and SOFA with SCR for the
three units.\192\ On a per-unit basis, the visibility improvement at
the most impacted Class I area from this control option was 0.52 to
0.57 dv, and across all three units the sum of the improvement was 1.62
dv. Thus, the application of this control option to all three units of
Laramie River Station was estimated to have a visibility benefit about
the same as the application of this control option to Hunter Unit 1.
The average cost-effectiveness ranged from $4,375/ton to $4,461/ton,
considerably higher than the corresponding value for Hunter Unit 1,
while the incremental cost-effectiveness ranged from $5,449 to $5,871/
ton which is very close to the corresponding value for Hunter Unit 1.
Finally, the incremental visibility improvement as compared to LNB and
SOFA with SNCR was significant, as it is for Hunter Unit 1. On the
other hand, at Dave Johnston Units 3 and 4 (for example), where EPA
rejected LNB and SOFA with SCR, the incremental cost-effectiveness
value of LNB and SOFA with SCR was much higher and incremental
visibility benefit lower than at Laramie River Station and higher than
the same metrics at Hunter Unit 1.\193\
---------------------------------------------------------------------------

    \192\ 79 FR 5032, 5047 (Jan. 30, 2014).
    \193\ 79 FR 5032, 5049.
---------------------------------------------------------------------------

    There are other BART determinations in which SCR has been selected
as BART (either alone or in conjunction with LNB and SOFA) based on
similar metrics, although those determinations may not have explicitly
discussed incremental cost-effectiveness and incremental visibility
benefits on a per-unit basis. First, the State of Colorado selected,
and the EPA approved, SCR as NOX BART for Public Service
Company's Hayden Station, Units 1 and 2.\194\ Hayden Units 1 and 2 were
equipped with first generation LNB and over-fire air (OFA) installed in
1999.\195\ In its BART determination, Colorado considered these
existing controls as given and analyzed as feasible controls upgraded
LNB, SNCR, and SCR. Based on an average cost-effectiveness of $3,385/
ton and $4,064/ton, incremental cost-effectiveness (as compared with
LNB and OFA with SNCR) of $5,326/ton and $7,331/ton, and visibility
improvement of 1.12 dv and 0.85 dv at the most impacted Class I area,
respectively, Colorado selected SCR as BART for Units 1 and 2. In this
case, due to the existing controls at Hayden Station, the cost-
effectiveness values for SCR for Hayden Units 1 and 2 should be
compared to the incremental cost-effectiveness values (as compared with
LNB and SOFA, and with LNB and SOFA with SNCR) for SCR for Hunter Unit
1, and similarly for incremental visibility benefits. We think they are
comparable, particularly for Hayden Unit 2, and considering that Hunter
Unit 1 significantly impacts several Class I areas, while Colorado
selected SCR for Hayden based solely on the visibility improvement at
the most impacted Class I area, Mt. Zirkel Wilderness.
---------------------------------------------------------------------------

    \194\ 77 FR 18069 (Mar. 26, 2012) (proposal); 77 FR 76871 (Dec.
31, 2012) (final).
    \195\ Colorado Department of Health and Environment, Air
Pollution Control Division, Best Available Retrofit Technology
(BART) Analysis of Control Options For Public Service Company--
Hayden Station, p. 5, available at https://www.colorado.gov/pacific/sites/default/files/AP_PO_Hayden-Power-Plant_0.pdf.
---------------------------------------------------------------------------

    Another comparable determination can be found in EPA's FIP for
Arizona Public Service's Cholla Power Plant, Units 2, 3, and 4, in
which EPA determined that NOX BART was SCR.\196\ Similarly
to Colorado's determination for Hayden, EPA considered the existing
controls, LNB and OFA, at the three units and estimated average cost-
effectiveness values for SCR of $3,114/ton, $3,472/ton, and $3,395/ton,
and incremental cost-effectiveness values (as compared to LNB and OFA
with SNCR) of $3,257/ton, $3,811/ton, and $3,661/ton, respectively, for
Units 2, 3, and 4. EPA's modeling showed a source-wide visibility
improvement for SCR of 1.34 dv at the most impacted Class I area. Based
on these metrics, EPA determined NOX BART to be SCR for the
three units. In this case, as with Hayden, the average cost-
effectiveness of SCR at Cholla should be compared with the incremental
cost-effectiveness of SCR (as compared with just LNB and SOFA) at
Hunter Unit 1. The cost-effectiveness values for Hunter Unit 1 are
somewhat higher than at Cholla, but on the other hand the source-wide
visibility improvement at Hunter Units 1 and 2 (as obtained by summing
the per-unit improvements from Units 1 and 2) \197\ from LNB and SOFA
with SCR is 2.759 dv at the most impacted Class I area, with
incremental visibility improvements of 1.29 dv and 0.932 dv over LNB
and SOFA and LNB and SOFA with SNCR, respectively. These visibility
improvements are very much in line with those at Cholla, and given that
the incremental cost-effectiveness of SCR at Hunter Unit 1 is still
reasonable, the comparison with Cholla also supports selection of SCR
for Hunter Unit 1. We invite comment on other potentially relevant BART
determinations and our methodology generally.
---------------------------------------------------------------------------

    \196\ 77 FR 42834 (July 20, 2012) (proposal); 77 FR 72512,
72514-15 (Dec. 5, 2012) (final).
    \197\ We use the source-wide number here to compare with the
Cholla determination; in addition as explained above we must
consider source-wide visibility improvements.
---------------------------------------------------------------------------

    Based on these comparisons to Laramie River Station, Hayden
Station, Dave Johnston Units 3 and 4, and Cholla Power Plant, we think
that selection of LNB and SOFA with SCR as BART for Hunter Unit 1 would
be fully consistent with these prior actions. For Hunter

Unit 1, LNB and SOFA with SCR is very cost-effective, at $2,380/ton on
an average basis (counting the costs and emission reductions from the
combination of the three control technology elements) and at $5,268/ton
on an incremental basis compared to LNB with SOFA and SNCR. Compared to
LNB with SOFA, the incremental cost effectiveness is $4,813/ton, which
also compares favorably to the incremental cost effectiveness that
supported the selection of LNB with SOFA and SCR for Laramie River
Station. For Hunter Unit 1, LNB and SOFA with SCR provides substantial
visibility benefits at several Class I areas that are similar to those
from Laramie River Station and larger than those from Dave Johnson
Units 3 and 4. For example, the visibility improvement from that
control option installed on a single unit is 1.342 dv at Arches NP,
1.545 dv at Canyonlands NP, and 1.113 at Capitol Reef NP. These
comparisons show that costs are justified in light of the substantial
visibility benefits, both total and incremental.
    In the case of Hunter, the unit level visibility improvements
justify the most stringent level of control, SCR, for each of the two
Hunter units. Necessarily, when we consider the source-wide visibility
improvements, they will be larger and also justify the most stringent
level of control. In addition, the unit level visibility improvements
and source-wide visibility improvements (as derived by summing the unit
level visibility improvements) at other impacted Class I areas,
particularly Arches NP and Capitol Reef NP, support the most stringent
level of control. Accordingly, for Hunter Unit 1, we propose to find
that BART for NOX is LNB and SOFA with SCR, represented by
an emission limit of 0.07 lb/MMBtu (30-day rolling average). The
proposed BART emission limit of 0.07 lb/MMBtu allows for a sufficient
margin of compliance for a 30-day rolling average limit that would
apply at all times, including startup, shutdown, and malfunction.\198\
We are also proposing monitoring, recordkeeping, and reporting
requirements as described in our proposed regulatory text for 40 CFR
52.2336.
---------------------------------------------------------------------------

    \198\ Emission limits such as BART are required to be met on a
continuous basis. See 70 FR 39104, 39172 (July 6, 2005) (stating
that emissions limits including BART are to be met on a ``continuous
basis'' in the BART Guidelines, section V); 42 U.S.C. 7602(k)
(noting that emission limits are to be on ``a continuous basis'').
---------------------------------------------------------------------------

    Under 40 CFR 51.308(e)(1)(iv), ``each source subject to BART [is]
required to install and operate BART as expeditiously as practicable,
but in no event later than five years after approval of the
implementation plan revision.'' In light of the considerable effort
involved to retrofit SCR, we propose that five years is as
expeditiously as practicable. Therefore, we propose a compliance
deadline of five years from the date our final FIP becomes effective.
b. Hunter Unit 2
    Generally speaking, Hunter Unit 2 is identical to Hunter Unit 1.
The Hunter Unit 2 boiler is of tangential-fired design with newer
generation low-NOX burners and separated overfire air which
were installed in spring 2011. Hunter Unit 2 currently achieves an
annual emission rate of approximately 0.20 lb/MMBtu with these
combustion controls. Under Utah's submitted regional haze SIP, Unit 1
is subject to a state-law NOX emission limit of 0.26 lb/
MMBtu on a 30-day rolling average. Prior to the installation of LNB and
SOFA the unit operated with an actual annual emission rate of about
0.38 lb/MMBtu.
Step 1: Identify All Available NOX Control Technologies
    For the same reasons as for Hunter Unit 1, we propose to adopt the
identification of available NOX control technologies in
PacifiCorp's 2012 BART analysis to satisfy Step 1, and we refer the
reader to the 2012 PacifiCorp BART analysis for details on those
control technologies.
Step 2: Eliminate Technically Infeasible Options
    In its 2012 BART analysis,\199\ PacifiCorp eliminated available
NOX control technologies that PacifiCorp evaluated as
technologically infeasible for Hunter Unit 2. The remaining
technologically feasible control technologies are the combustion
controls, LNB and SOFA, and the post-combustion controls, SNCR and SCR.
---------------------------------------------------------------------------

    \199\ PacifiCorp BART Analysis for Hunter Unit 2, pp. 2.b-105--
2.a-122 (2012).
---------------------------------------------------------------------------

    As with Hunter Unit 1, we agree with PacifiCorp's evaluation of
technologically available controls for Hunter Unit 2 and propose to
adopt it for Step 2.
Step 3: Evaluate Control Effectiveness of Remaining Control
Technologies
    As noted previously, Hunter Unit 2 is currently achieving an actual
annual emission rate of approximately 0.20 lb/MMBtu with LNB and SOFA.
This represents a 48.2 percent reduction from the baseline emission
rate of 0.38 lb/MMBtu.
    SCR can achieve performance emission rates as low as 0.04 to 0.07
lb/MMBtu on an annual basis.\200\ For this analysis, consistent with
our actions elsewhere, as well with PacifiCorp's analysis, we use an
annual emission rate of 0.05 lb/MMBtu for SCR, which when combined with
LNB and SOFA achieves an overall control efficiency of 86.9 percent.
For this analysis, consistent with our actions elsewhere, as well with
PacifiCorp's analysis, we use an annual emission rate of 0.05 lb/MMBtu
for SCR, which when combined with LNB and SOFA achieves an overall
control efficiency of 86.9 percent.
---------------------------------------------------------------------------

    \200\ Srivastava, R., Hall, R., Khan, S., Lani, B., & Culligan,
K., Nitrogen Oxides Emission Control Options for Coal-Fired Utility
Boilers, 55 J. Air & Waste Mgmt. Assoc. 1367, 1385-86 (2005).
---------------------------------------------------------------------------

    As with Hunter Unit 1, we evaluated post-combustion control
technologies, SNCR and SCR, in combination with combustion controls.
Our evaluation is the same as for Hunter Unit 1. A summary of emissions
projections for the control options evaluated is provided in Table 19.

                  Table 19--Summary of NOX BART Analysis Control Technologies for Hunter Unit 2
----------------------------------------------------------------------------------------------------------------
                                           Control        Annual emission       Emissions          Remaining
           Control option             effectiveness (%)   rate (lb/MMBtu)    reduction (tpy)    emissions (tpy)
----------------------------------------------------------------------------------------------------------------
LNB/SOFA+SCR........................               86.9               0.05              5,230                788
LNB/SOFA+SNCR.......................               59.2               0.16              3,562              2,457
LNB/SOFA............................               48.2               0.20              2,902              3,117
Baseline \1\........................  .................               0.38  .................              6,018
----------------------------------------------------------------------------------------------------------------
\1\ Baseline emissions were determined by averaging the annual emissions from 2001 to 2003 as reported to EPA
  Air Markets Program Data available at http://ampd.epa.gov/ampd/.

Step 4: Evaluate Impacts and Document Results
Part 1--Costs of Compliance
    We obtained capital costs for LNB and SOFA from the 2014 PacifiCorp
BART analysis. PacifiCorp did not report any operating and maintenance
costs for LNB and SOFA. Similarly, we obtained capital cost estimates
for LNB and SOFA with SNCR from the 2014 PacifiCorp BART analysis.
However, for operating and maintenance costs we propose to rely on the
draft 2015 draft SNCR chapter of the CCM. Refer to the ATP report for
details. Capital costs for LNB and SOFA with SCR were also obtained
from the 2014 PacifiCorp BART analysis. However, PacifiCorp's capital
costs were adjusted to account for items that were double-counted or
should not be allowed under the CCM, such as AFUDC.\201\ In addition,
the capital costs were adjusted to account for a significant
overestimation of the catalyst volume and related costs. These
adjustments are documented in the ATP report and associated spread
sheet. A discussion of operating and maintenance costs of SCR is also
included in the ATP report. For the reasons given in the report, we
propose to adopt the cost estimates contained in it.
---------------------------------------------------------------------------

    \201\ See 79 FR 5032, 5133 (Jan. 30, 2014) (discussing reasons
for rejecting use of AFUDC).
---------------------------------------------------------------------------

    A summary of our proposed cost estimates for all control options is
presented in Table 20.

                                                  Table 20--Summary of NOX BART Costs on Hunter Unit 2
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Average cost
            Control option                Total capital     Indirect annual     Direct annual    Total annual cost      Emissions      effectiveness ($/
                                            investment            cost               cost                            reductions (tpy)         ton)
--------------------------------------------------------------------------------------------------------------------------------------------------------
LNB/SOFA..............................              $8.6M              $0.9M                $0M              $0.9M              2,902               $298
LNB/SOFA/SNCR.........................              16.0M               1.6M               1.9M               3.5M              3,562                968
LNB/SOFA/SCR..........................             108.1M               10.3               2.4M              12.7M              5,230              2,432
--------------------------------------------------------------------------------------------------------------------------------------------------------

Parts 2 and 3--Energy and Non-Air Quality Environmental Impacts of
Compliance
    The energy and non-air quality impacts for Hunter Unit 2 are nearly
identical to those for Hunter Unit 1 as discussed previously.
Accordingly, for the same reasons as for Hunter Unit 1, we propose to
determine that we have adequately considered these impacts by including
cost of additional energy in cost effectiveness and assessing non-air
quality environmental impacts as insufficient to eliminate or weigh
against any of the BART options.
Part 4--Remaining Useful Life
    PacifiCorp assumes a remaining useful life of at least 20 years for
Hunter Unit 2 in its BART analysis, and has not indicated any intention
to retire, or curtail generation from, Hunter Unit 2. Therefore, this
factor does not preclude any of the control options considered. In
addition, this factor is consistent with our BART calculation of cost
effectiveness because annualized costs have been calculated over a 20
year period for each of the control options considered. We propose that
this gives adequate consideration to this factor.
Step 5: Evaluate Visibility Impacts
    Table 21 presents the highest of the 98th percentile visibility
improvements at the affected Class I areas for the three meteorological
years modeled, 2001 through 2003. Tables 22 and 23 present the number
of days (summed across three years) with impacts greater than the
contribution and causation thresholds--0.5 dv and 1.0 dv, respectively.

                                Table 21--Hunter Unit 2--Visibility Improvements
----------------------------------------------------------------------------------------------------------------
                                                           LNB with SOFA    LNB with SOFA and  LNB with SOFA and
                      Class I area                          ([Delta]dv)      SNCR ([Delta]dv)   SCR ([Delta]dv)
----------------------------------------------------------------------------------------------------------------
Arches NP..............................................              0.569              0.711              1.080
Black Canyon of the Gunnison NP........................              0.153              0.189              0.279
Bryce Canyon NP........................................              0.234              0.291              0.429
Canyonlands NP.........................................              0.658              0.822              1.250
Capitol Reef NP........................................              0.491              0.623              0.879
Flat Tops WA...........................................              0.180              0.223              0.328
Grand Canyon NP........................................              0.275              0.340              0.506
Mesa Verde NP..........................................              0.182              0.225              0.344
Zion NP................................................              0.144              0.178              0.262
----------------------------------------------------------------------------------------------------------------

                             Table 22--Hunter Unit 2--Days Greater Than 0.5 Deciview
                                               [Three year total]
----------------------------------------------------------------------------------------------------------------
                                                           LNB with SOFA    LNB with SOFA and  LNB with SOFA and
            Class I area               Baseline (days)         (days)          SNCR (days)         SCR (days)
----------------------------------------------------------------------------------------------------------------
Arches NP...........................                293                276                268                245
Black Canyon of the Gunnison NP.....                 68                 57                 55                 49
Bryce Canyon NP.....................                 42                 39                 37                 30
Canyonlands NP......................                359                336                331                317
Capitol Reef NP.....................                175                163                161                152

Flat Tops WA........................                 77                 64                 63                 57
Grand Canyon NP.....................                 49                 46                 45                 40
Mesa Verde NP.......................                 82                 72                 66                 59
Zion NP.............................                 29                 24                 23                 22
----------------------------------------------------------------------------------------------------------------

                             Table 23--Hunter Unit 2--Days Greater Than 1.0 Deciview
                                               [Three year total]
----------------------------------------------------------------------------------------------------------------
                                                           LNB with SOFA    LNB with SOFA and  LNB with SOFA and
            Class I area               Baseline (days)         (days)          SNCR (days)         SCR (days)
----------------------------------------------------------------------------------------------------------------
Arches NP...........................                170                151                145                131
Black Canyon of the Gunnison NP.....                 22                 16                 13                 11
Bryce Canyon NP.....................                 22                 21                 19                 16
Canyonlands NP......................                240                221                218                198
Capitol Reef NP.....................                118                113                111                105
Flat Tops WA........................                 31                 20                 20                 14
Grand Canyon NP.....................                 32                 25                 25                 22
Mesa Verde NP.......................                 32                 22                 20                 14
Zion NP.............................                 14                 11                  9                  8
----------------------------------------------------------------------------------------------------------------

    Select BART.
    A summary of our impacts analysis for Hunter Unit 2 is presented in
Table 24.

                                                   Table 24--Summary of Hunter Unit 2 Impacts Analysis
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                          Annual                  Total                                                     Visibility impacts *
                                         emission    Emission    annual     Average  cost     Incremental  cost    -------------------------------------
            Control option              rate (lb/   reduction     costs     effectiveness   effectiveness ($/ton)     Improvement     Days >     Days >
                                          MMBtu)      (tpy)    (million$)      ($/ton)                                   (dv)         0.5 dv     1.0 dv
--------------------------------------------------------------------------------------------------------------------------------------------------------
LNB with SOFA........................         0.20      2,902       $0.9M            $298  .......................           0.658        336        221
LNB with SOFA and SNCR...............         0.16      3,562        3.5M             968  $3,913.................           0.822        331        218
LNB with SOFA and SCR................         0.05      5,230       12.7M           2,432  $5,558 (compared to LNB           1.250        317        198
                                                                                with SOFA and SNCR).
                                                                                $5,092 (compared to LNB
                                                                                with SOFA)..
--------------------------------------------------------------------------------------------------------------------------------------------------------
* At the most impacted Class I area, Canyonlands National Park.

    In determining what to co-propose as BART, we have taken into
consideration all five of the statutory factors required by the CAA:
The costs of compliance, the energy and non-air quality environmental
impacts of compliance, any existing pollution control technology in use
at the source, the remaining useful life of the source, and the degree
of improvement in visibility which may reasonably be anticipated to
result from the use of such technology. Later on we provide a
justification for our selection of BART, including an explanation of
how each of the CAA factors was used in that selection.
    We have considered the energy and non-air quality environmental
impacts of compliance and propose to find that they do not appreciably
favor one control option over another, or preclude a particular control
option from selection. As explained for Hunter Unit 1, the existing
pollution controls have been accounted for in our evaluation of BART,
and also would not favor or preclude any of the control options
considered. And finally, we have considered the remaining useful life
of the source and find that it is sufficiently long (greater than 20
years) so as not to favor or preclude any of the control options. As a
result, the remaining factors--the costs of compliance and visibility
improvement--are the primary factors that lead us to our proposed BART
selection for Hunter Unit 2.
    In order to select BART we propose (for the same reasons as for
Hunter Unit 1) to weigh the costs of compliance against visibility
impacts by generally comparing them with BART determinations that have
been made elsewhere. Specifically, we propose to compare the average
cost-effectiveness, incremental cost-effectiveness, visibility
improvement, and incremental visibility improvement for LNB and SOFA
with SCR with BART determinations where the EPA and States have based
their determination on the same metrics. The most comparable
determinations are the same as for Hunter Unit 1: Laramie River
Station, Hayden Station, and Cholla Power Plant.

    Based on these comparisons, we think LNB and SOFA with SCR for
Hunter 2 is fully consistent with the other BART determinations. LNB
and SOFA with SCR is very cost-effective at $2,432/ton, and provides
substantial visibility benefits at several Class I areas. For example,
the visibility improvement from that control option is 1.250 dv at
Canyonlands NP and 1.080 dv at Arches NP. The incremental cost-
effectiveness of SCR, $5,558/ton, is by comparison also reasonable.
This comparison also shows that costs are justified in light of the
substantial visibility benefits, both total and incremental.
    In the case of Hunter, the unit level visibility improvements
justify the most stringent level of control, SCR, for each of the two
Hunter units. Necessarily, when we consider the source-wide visibility
improvements, they will be larger and also justify the most stringent
level of control. In addition, the unit level visibility improvements
and source-wide visibility improvements (as derived by summing the unit
level visibility improvements) at other impacted Class I areas,
particularly Arches NP and Capitol Reef NP, support the most stringent
level of control.
    Accordingly, for Hunter Unit 2, we propose to find that BART for
NOX is LNB and SOFA with SCR, represented by an emission
limit of 0.07 lb/MMBtu (30-day rolling average). The proposed BART
emission limit of 0.07 lb/MMBtu allows for a sufficient margin of
compliance for a 30-day rolling average limit that would apply at all
times, including startup, shutdown, and malfunction.\202\ We are also
proposing monitoring, recordkeeping, and reporting requirements as
described in our proposed regulatory text for 40 CFR 52.2336.
---------------------------------------------------------------------------

    \202\ Emission limits such as BART are required to be met on a
continuous basis. See 70 FR 39104, 39172 (July 6, 2005) (stating
that emissions limits including BART are to be met on a ``continuous
basis'' in the BART Guidelines, section V); 42 U.S.C. 7602(k)
(noting that emission limits are to be on ``a continuous basis'').
---------------------------------------------------------------------------

    Under 40 CFR 51.308(e)(1)(iv), ``each source subject to BART [is]
required to install and operate BART as expeditiously as practicable,
but in no event later than 5 years after approval of the implementation
plan revision.'' In light of the considerable effort involved to
retrofit SCR, we propose that five years is as expeditiously as
practicable. Therefore, we propose a compliance deadline of five years
from the date our final FIP becomes effective.
3. Huntington Power Plant
    As described previously in section IV.A, Huntington Units 1 and 2
were determined to be subject to BART. PacifiCorp's Huntington Power
Plant (Huntington), is located in Huntington City, Utah, and consists
of a total of the two electric utility steam generating units.
Huntington Units 1 and 2 have a nameplate generating capacity of 498 MW
each.\203\ The boilers are tangentially fired pulverized coal boilers,
burning bituminous coal from the nearby Deer Creek Mine.
---------------------------------------------------------------------------

    \203\ See U.S. Energy Information Administration, Electric
Generating Capacity for 2011 (taken from Form EIA-860). See ``EIA
existing generating units 2011.xls'' spreadsheet in the docket.
---------------------------------------------------------------------------

    Our evaluation of BART for Huntington Unit 1 and 2 follows the
Guidelines for BART Determinations Under the Regional Haze Rule, which
are found in appendix Y to 40 CFR part 51. For Huntington Units 1 and
2, the BART Guidelines are mandatory because the combined capacity for
all units at the Huntington facility is greater than 750 MW.\204\ Under
the Guidelines, cost estimates for control technologies should be based
on the CCM, where possible.
---------------------------------------------------------------------------

    \204\ See 40 CFR 51.302(e)(1)(ii)(B) (``The determination of
BART for fossil-fuel fired power plants having a total generating
capacity greater than 750 megawatts must be made pursuant to the
guidelines in appendix Y of this part.'').
---------------------------------------------------------------------------

    The BART Guidelines establish presumptive NOX limits for
coal-fired EGUs greater than 200 MW located at greater than 750 MW
power plants that are operating without post-combustion controls. For
the tangential-fired boilers burning bituminous coal at Huntington,
that presumptive limit is 0.28 lb/MMBtu.\205\ The BART Guidelines
provide that the five factor analysis may result in a limit that is
different than the presumptive limit, and the presumptive limits do not
obviate the need to determine BART on a case-by-case basis considering
the five factors.\206\
---------------------------------------------------------------------------

    \205\ 40 CFR part 51, appendix Y, IV.E.5, Table. 1.
    \206\ See 40 CFR 51.301 (defining BART); 40 CFR 51.308(e).
---------------------------------------------------------------------------

    PacifiCorp provided BART analyses for Huntington 1 and 2 to Utah in
2012 and 2014 which we utilize in our proposed BART evaluation
here.\207\ Although we are using some information provided by Utah and
PacifiCorp, we have independently evaluated all five statutory BART
factors.
---------------------------------------------------------------------------

    \207\ See PacifiCorp BART Analysis for Huntington Unit 1(2012);
PacifiCorp BART Analysis for Huntington Unit 2 (2012); see also
Chapter 2 of the Technical Support Document for Utah's Regional Haze
BART Submittal; PacifiCorp's BART Analysis Update for Hunter Units 1
and 2 and Huntington Units 1 and 2 (2014).
---------------------------------------------------------------------------

a. Huntington Unit 1
    The Huntington Unit 1 boiler is of tangential-fired design with
newer generation low-NOX burners and separated overfire air
which were installed in fall 2010. Huntington Unit 1 currently achieves
an annual emission rate of approximately 0.22 lb/MMBtu with these
combustion controls. Under Utah's submitted regional haze SIP, Unit 1
is subject to a state-law NOX emission limit of 0.26 lb/
MMBtu on a 30-day rolling average. Prior to the installation of LNB and
SOFA the unit operated with an actual annual emission rate of about
0.37 lb/MMBtu.
Step 1: Identify All Available NOX Control Technologies
    In its 2012 BART analysis for Huntington Unit 1, PacifiCorp
identified several NOX control technologies, both for
combustion controls and post-combustion controls.\208\ The combustion
controls identified by PacifiCorp include: Low-NOX burners
and separated overfire air (LNB and SOFA overfire air; already
installed), rotating overfire air, neural network optimization system,
flue gas recirculation, gas reburn, fuel lean gas reburn, coal
switching, water injection, and others. Post-combustion control options
identified by PacifiCorp include: SNCR, RRI, SCR, and others.
---------------------------------------------------------------------------

    \208\ PacifiCorp BART Analysis for Huntington Unit 1, p. 2.c-60
(2012).
---------------------------------------------------------------------------

    We note that the combustion controls, LNB and SOFA, have already
been installed on Huntington Unit 1, and so we consider them here as
``any existing controls'' under the third statutory factor. In
addition, the BART Guidelines recognize that ``[c]ombinations of
inherently lower-emitting processes and add-on controls'' are a
category of retrofit controls which can be considered.\209\
Accordingly, the inherently lower-emitting combustion controls, LNB and
SOFA, are evaluated in combination with the add-on controls, SNCR and
SCR.
---------------------------------------------------------------------------

    \209\ 40 CFR part 51 appendix Y.
---------------------------------------------------------------------------

    We have reviewed PacifiCorp's review of NOX control
technologies and find it to be comprehensive. We propose to adopt it to
satisfy Step 1 and we refer to the 2012 PacifiCorp BART analysis for
details on the available NOX control technologies.
Step 2: Eliminate Technically Infeasible Options
    In its 2012 BART analysis,\210\ PacifiCorp eliminated available
NOX control technologies that PacifiCorp evaluated as
technologically infeasible for Huntington Unit 1. The remaining
technologically feasible control technologies are the combustion

controls, LNB and SOFA, and the post-combustion controls, SNCR and SCR.
---------------------------------------------------------------------------

    \210\ PacifiCorp BART Analysis for Huntington Unit 1, pp. 2.c-
61--2.c-77 (2012).
---------------------------------------------------------------------------

    We agree with PacifiCorp's evaluation of technologically available
controls for Huntington Unit 1 and propose to adopt it for Step 2.
Step 3: Evaluate Control Effectiveness of Remaining Control
Technologies
    As noted previously, Huntington Unit 1 is currently achieving an
actual annual emission rate of approximately 0.22 lb/MMBtu with LNB and
SOFA. This represents a 41.5 percent reduction from the baseline
emission rate of 0.37 lb/MMBtu.
    The post-combustion control technologies, SNCR and SCR, have been
evaluated in combination with combustion controls. That is, the inlet
concentration to the post-combustion controls is assumed to be 0.22 lb/
MMBtu (annual). This allows the equipment and operating and maintenance
costs of the post-combustion controls to be minimized based on the
lower inlet NOX concentration.
    Typically, SNCR reduces NOX an additional 20 to 30
percent above combustion controls without excessive NH3
slip.\211\ For this analysis, the control efficiency of SNCR has been
calculated based on the formula in the 2015 draft CCM SNCR
chapter,\212\ which for Huntington Unit 1 yields an additional
reduction of 21.7 percent after combustion controls. When combined with
LNB and SOFA, SNCR is anticipated to achieve an annual emission rate of
0.17 lb/MMBtu, corresponding to an overall control efficiency of 54.2
percent.
---------------------------------------------------------------------------

    \211\ Institute of Clean Air Companies, White Paper, SNCR for
Controlling NOX Emissions, pp. 4, 9 (Feb. 2008).
    \212\ See [DRAFT] 2015 SNCR CCM (July 2015), Figure 1.1c: SNCR
NOX Reduction Efficiency Versus Baseline NOX
Levels for Coal-fired Utility Boilers.
---------------------------------------------------------------------------

    SCR can achieve performance emission rates as low as 0.04 to 0.07
lb/MMBtu on an annual basis.\213\ For this analysis, consistent with
our actions elsewhere, as well with PacifiCorp's analysis, we use an
annual emission rate of 0.05 lb/MMBtu for SCR, which when combined with
LNB and SOFA achieves an overall control efficiency of 86.7 percent.
---------------------------------------------------------------------------

    \213\ Srivastava, R., Hall, R., Khan, S., Lani, B., & Culligan,
K., Nitrogen Oxides Emission Control Options for Coal-Fired Utility
Boilers, 55 J. Air & Waste Mgmt. Assoc. 1367, 1367-88 (2005).
---------------------------------------------------------------------------

    A summary of emissions projections for the control options
evaluated is provided in Table 25.

                Table 25--Summary of NOX BART Analysis Control Technologies for Huntington Unit 1
----------------------------------------------------------------------------------------------------------------
                                                      Control         Annual         Emissions       Remaining
                 Control option                    effectiveness   emission rate     reduction       emissions
                                                        (%)         (lb/MMBtu)         (tpy)           (tpy)
----------------------------------------------------------------------------------------------------------------
LNB/SOFA +SCR...................................            86.7            0.05           5,092             784
LNB/SOFA +SNCR..................................            54.2            0.17           3,185           2,692
LNB/SOFA........................................            41.5            0.22           2,440           3,436
Baseline \1\....................................  ..............            0.37  ..............           5,876
----------------------------------------------------------------------------------------------------------------
\1\ Baseline emissions were determined by averaging the annual emissions from 2001 to 2003 as reported to EPA
  Air Markets Program Data available at http://ampd.epa.gov/ampd/.

Step 4: Evaluate Impacts and Document Results
Part 1--Costs of Compliance
    We obtained capital costs for LNB and SOFA from the 2014 PacifiCorp
BART analysis. PacifiCorp did not report any operating and maintenance
costs for LNB and SOFA. Similarly, we obtained capital cost estimates
for LNB and SOFA with SNCR from the 2014 PacifiCorp BART analysis.
However, for operating and maintenance costs we propose to rely on the
draft 2015 draft SNCR chapter of the CCM. Refer to the ATP report for
details. Capital costs for LNB and SOFA with SCR were also obtained
from the 2014 PacifiCorp BART analysis. However, PacifiCorp's capital
costs were adjusted to account for items that were double-counted or
should not be allowed under the CCM, such as AFUDC.\214\ In addition,
the capital costs were adjusted to account for a significant
overestimation of the catalyst volume and related costs. These
adjustments are documented in the ATP report and associated spread
sheet. A discussion of operating and maintenance costs of SCR is also
included in the ATP report. For the reasons given in the report, we
propose to adopt the cost estimates contained in it.
---------------------------------------------------------------------------

    \214\ See 79 FR 5032, 5133 (Jan. 30, 2014) (discussing reasons
for rejecting use of AFUDC).
---------------------------------------------------------------------------

    A summary of our proposed cost estimates for all control options is
presented in Table 26.

                                                Table 26--Summary of NOX BART Costs on Huntington Unit 1
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Emissions     Average Cost
                     Control option                        Total capital     Indirect      Direct annual   Total annual     reductions     effectiveness
                                                            investment      annual cost        cost            cost            (tpy)          ($/ton)
--------------------------------------------------------------------------------------------------------------------------------------------------------
LNB/SOFA................................................           $8.1M           $0.8M             $0M           $0.8M           2,440            $332
LNB/SOFA/SNCR...........................................           15.5M            1.5M            2.0M            3.5M           3,185           1,098
LNB/SOFA/SCR............................................          107.8M           10.3M            2.5M           12.8M           5,092           2,515
--------------------------------------------------------------------------------------------------------------------------------------------------------

Parts 2 and 3--Energy and Non-Air Quality Environmental Impacts of
Compliance
    SNCR slightly reduces the thermal efficiency of a boiler as the
reduction reaction uses thermal energy from the boiler, decreasing the
energy available for power generation.\215\ Using the CCM, we have
calculated the electrical power consumption of SNCR to be 361,000 kW-hr
per year for Huntington Unit 1.
---------------------------------------------------------------------------

    \215\ EPA Air Pollution Control Cost Manual, pp. 1-21 (6th ed.
2002).
---------------------------------------------------------------------------

    For SCR, the thermal efficiency is much more reduced because the
new ductwork and the reactor's catalyst layers decrease the flue gas
pressure. As

a result, additional fan power is necessary to maintain the flue gas
flow rate through the ductwork and reactor. Using the CCM, we have
calculated the electrical power consumption of SCR to be approximately
18,617,000 kW-hr per year for Huntington Unit 1.
    Both SCR and SNCR require some minimal electricity to service
pretreatment and injection equipment, pumps, compressors, and control
systems. The energy requirements described earlier are not significant
enough to warrant elimination of either SNCR or SCR as BART. In
addition, the cost of the additional energy requirements has been
included in our cost effectiveness calculations.
    SNCR and SCR will slightly increase the quantity of ash that will
need to be disposed. In addition, transportation and storage of
chemical reagents may result in spills or releases. However, these non-
air quality environmental impacts do not warrant elimination of either
SNCR or SCR as BART.
    There are no additional energy requirements associated with the new
LNB and SOFA, and no significant non-air quality environmental impacts.
    In summary, we propose to determine that we have adequately
considered these impacts by including cost of additional energy in cost
effectiveness and assessing non-air quality environmental impacts as
insufficient to eliminate or weigh against any of the BART options.
Part 4--Remaining Useful Life
    PacifiCorp assumes a remaining useful life of at least 20 years for
Huntington Unit 1 in its BART analysis, and has not indicated any
intention to retire, or curtail generation from, Huntington Unit 1.
Therefore, this factor does not preclude any of the control options
considered. In addition, this factor does not impact our BART
calculation of cost effectiveness because annualized costs have been
calculated over a 20 year period for each of the control options
considered. We propose that this gives adequate consideration to this
factor.
Step 5: Evaluate Visibility Impacts
    Table 27 presents the highest of the 98th percentile visibility
improvements at the affected Class I areas for the three meteorological
years modeled, 2001 through 2003. Tables 28 and 29 present the number
of days (summed across three years) with impacts greater than the
contribution and causation thresholds--0.5 dv and 1.0 dv, respectively.

                              Table 27--Huntington Unit 1--Visibility Improvements
----------------------------------------------------------------------------------------------------------------
                                                                                LNB with SOFA   LNB with SOFA
                          Class I Area                             LNB with SOFA     and SNCR         and SCR
                                                                    ([Delta]dv)     ([Delta]dv)     ([Delta]dv)
----------------------------------------------------------------------------------------------------------------
Arches NP.......................................................           0.684           0.907           1.488
Black Canyon of the Gunnison NP.................................           0.156           0.205           0.328
Bryce Canyon NP.................................................           0.222           0.292           0.473
Canyonlands NP..................................................           0.851           1.133           1.881
Capitol Reef NP.................................................           0.493           0.651           1.108
Flat Tops WA....................................................           0.181           0.239           0.383
Grand Canyon NP.................................................           0.200           0.262           0.419
Mesa Verde NP...................................................           0.215           0.284           0.462
Zion NP.........................................................           0.150           0.198           0.320
----------------------------------------------------------------------------------------------------------------

                           Table 28--Huntington Unit 1--Days Greater Than 0.5 Deciview
                                               [Three year total]
----------------------------------------------------------------------------------------------------------------
                                                                                LNB with SOFA
                  Class I Area                       Baseline      LNB with SOFA     and SNCR      LNB with SOFA
                                                      (days)          (days)          (days)      and SCR (days)
----------------------------------------------------------------------------------------------------------------
Arches NP.......................................             237             221             210             180
Black Canyon of the Gunnison NP.................              45              33              30              23
Bryce Canyon NP.................................              36              26              25              19
Canyonlands NP..................................             277             249             244             210
Capitol Reef NP.................................             131             117             116              99
Flat Tops WA....................................              64              41              37              27
Grand Canyon NP.................................              40              35              34              27
Mesa Verde NP...................................              63              46              41              30
Zion NP.........................................              21              16              16              14
----------------------------------------------------------------------------------------------------------------

                           Table 29--Huntington Unit 1--Days Greater than 1.0 Deciview
                                               [Three year total]
----------------------------------------------------------------------------------------------------------------
                                                                                LNB with SOFA
                  Class I Area                       Baseline      LNB with SOFA     and SNCR      LNB with SOFA
                                                      (days)          (days)          (days)      and SCR (days)
----------------------------------------------------------------------------------------------------------------
Arches NP.......................................             146             121             117              86
Black Canyon of the Gunnison NP.................              16               7               7               3
Bryce Canyon NP.................................              19              13               9               5
Canyonlands NP..................................             175             153             143             117
Capitol Reef NP.................................              91              74              69              55

Flat Tops WA....................................              17               9               8               3
Grand Canyon NP.................................              19              13              12               9
Mesa Verde NP...................................              22              13              10               4
Zion NP.........................................              11               8               6               4
----------------------------------------------------------------------------------------------------------------

    Select BART.
    A summary of our impacts analysis for Huntington Unit 1 is
presented in Table 30.

                                                 Table 30--Summary of Huntington Unit 1 Impacts Analysis
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                        Annual                    Total                                                     Visibility impacts *
                                       emission     Emission      annual     Average cost      Incremental cost    -------------------------------------
           Control option             rate (lb/    reduction      costs      effectiveness   effectiveness ($/ton)    Improvement     Days >     Days >
                                        MMBtu)       (tpy)      (million$)      ($/ton)                                  (dv)         0.5 dv     1.0 dv
--------------------------------------------------------------------------------------------------------------------------------------------------------
LNB with SOFA......................         0.22        2,440        $0.8M            $332  ......................           0.851        249        153
LNB with SOFA and SNCR.............         0.17        3,185         3.5M           1,098  3,609.................           1.113        244        143
LNB with SOFA and SCR..............         0.05        5,092        12.8M           2,515  $4,879 (compared to              1.881        210        117
                                                                                LNB with SOFA and
                                                                                SNCR).
                                                                                $4,522 (compared to
                                                                                LNB with SOFA).
--------------------------------------------------------------------------------------------------------------------------------------------------------
* At the most impacted Class I area, Canyonlands National Park.

    In determining what to co-propose as BART, we have taken into
consideration all five of the statutory factors required by the CAA:
The costs of compliance, the energy and non-air quality environmental
impacts of compliance, any existing pollution control technology in use
at the source, the remaining useful life of the source, and the degree
of improvement in visibility which may reasonably be anticipated to
result from the use of such technology. Later on we provide a
justification for our selection of BART, including an explanation of
how each of the CAA factors was used in that selection.
    As described in step 1 previously, we have considered the existing
pollution control technology in use at the source. We note that
Huntington Unit 1 was equipped with LNB and SOFA in the fall of 2010 in
order to meet state-law requirements in the 2011 Utah RH SIP submittal,
which we did not approve. In this co-proposal we have to evaluate
control technologies and baseline emissions from the correct starting
point, that is, prior to the installation of the combustion controls
pursuant to state-law NOX limitations.\216\ As a result, we
used the period 2001-2003 as the appropriate period for baseline
emissions, in order to provide a realistic depiction of annual
emissions for Huntington Unit 1 prior to installation of combustion
controls.
---------------------------------------------------------------------------

    \216\ See 79 FR 5032, 5105-1 (Jan. 30, 2012).
---------------------------------------------------------------------------

    We have considered the energy and non-air quality environmental
impacts of compliance and propose to find that they do not appreciably
favor one control option over another, or preclude a particular control
option from selection. And finally, we have considered the remaining
useful life of the source and find that it is sufficiently long
(greater than 20 years) so as not to favor or preclude any of the
control options. As a result, the remaining factors--the costs of
compliance and visibility improvement--are the primary factors that
lead us to our proposed BART selection for Huntington Unit 1.
    Having already considered the other factors, in order to select
BART we propose to weigh the costs of compliance against visibility
impacts by generally comparing them with BART determinations that have
been made elsewhere. Specifically, we propose to compare the average
cost-effectiveness, incremental cost-effectiveness, visibility
improvement, and incremental visibility improvement for LNB and SOFA
with SCR with BART determinations where the EPA and States have based
their determination on the same metrics. The most comparable
determinations are the same as for Hunter Unit 1. The most comparable
determination appears to be in EPA's final action for Wyoming's
regional haze SIP, in which EPA promulgated a FIP for three units at
Laramie River Station and determined BART to be LNB and SOFA with SCR
for the three units.\217\ On a per-unit basis, the visibility
improvement from that control option was 0.52 to 0.57 dv, and across
all three units the sum of the improvement was 1.62 dv. The average
cost-effectiveness ranged from $4,375/ton to $4,461/ton, while the
incremental cost-effectiveness ranged from $5,449 to $5,871/ton.
Finally, the incremental visibility improvement as compared to LNB and
SOFA with SNCR was significant. On the other hand, at Dave Johnston
Units 3 and 4 (for example), where EPA rejected LNB and SOFA with SCR,
the incremental cost-effectiveness value of LNB and SOFA with SCR was
much higher and incremental visibility benefit lower than at Laramie
River Station.\218\
---------------------------------------------------------------------------

    \217\ 79 FR 5032, 5047 (Jan. 30, 2014).
    \218\ 79 FR 5032, 5049.

---------------------------------------------------------------------------

    There are other BART determinations in which SCR has been selected
as BART (either alone or in conjunction with LNB and SOFA) based on
similar metrics, although those determinations may not have explicitly
discussed incremental cost-effectiveness and incremental visibility
benefits on a per-unit basis. First, the State of Colorado selected,
and the EPA approved, SCR as NOX BART for Public Service
Company's Hayden Station, Units 1 and 2.\219\ Hayden Units 1 and 2 were
equipped with first generation LNB and over-fire air (OFA) installed in
1999.\220\ In its BART determination, Colorado considered these
existing controls as given and analyzed as feasible controls upgraded
LNB, SNCR, and SCR. Based on an average cost-effectiveness of $3,385/
ton and $4,064/ton, incremental cost-effectiveness (as compared with
LNB and OFA with SNCR) of $5,326/ton and $7,331/ton, and visibility
improvement of 1.12 dv and 0.85 dv at the most impacted Class I area,
respectively, Colorado selected SCR as BART for Units 1 and 2. In this
case, due to the existing controls at Hayden Station, the cost-
effectiveness values for SCR for Hayden Units 1 and 2 should be
compared to the incremental cost-effectiveness values (as compared with
LNB and SOFA, and with LNB and SOFA with SNCR) for SCR for Huntington
Unit 1, and similarly for incremental visibility benefits. We think
they are comparable, particularly for Hayden Unit 2, and considering
that Huntington Unit 1 significantly impacts several Class I areas,
while Colorado selected SCR for Hayden based solely on the visibility
improvement at the most impacted Class I area, Mt. Zirkel Wilderness.
---------------------------------------------------------------------------

    \219\ 77 FR 18069 (Mar. 26, 2012) (proposal); 77 FR 76871 (Dec.
31, 2012) (final).
    \220\ Colorado Department of Health and Environment, Air
Pollution Control Division, Best Available Retrofit Technology
(BART) Analysis of Control Options For Public Service Company--
Hayden Station, p. 5, available at https://www.colorado.gov/pacific/sites/default/files/AP_PO_Hayden-Power-Plant_0.pdf.
---------------------------------------------------------------------------

    Another comparable determination can be found in EPA's FIP for
Arizona Public Service's Cholla Power Plant, Units 2, 3, and 4, in
which EPA determined that NOX BART was SCR.\221\ Similarly
to Colorado's determination for Hayden, EPA considered the existing
controls, LNB and OFA, at the three units and estimated average cost-
effectiveness values for SCR of $3,114/ton, $3,472/ton, and $3,395/ton,
and incremental cost-effectiveness values (as compared to LNB and OFA
with SNCR) of $3,257/ton, $3,811/ton, and $3,661/ton, respectively, for
Units 2, 3, and 4. EPA's modeling showed a source-wide visibility
improvement for SCR of 1.34 dv at the most impacted Class I area. Based
on these metrics, EPA determined NOX BART to be SCR for the
three units. In this case, as with Hayden, the average cost-
effectiveness of SCR at Cholla should be compared with the incremental
cost-effectiveness of SCR (as compared with just LNB and SOFA) at
Huntington Unit 1. The cost-effectiveness values for Huntington Unit 1
are somewhat higher than at Cholla, but on the other hand the source-
wide visibility improvement at Huntington Units 1 and 2 (as obtained by
summing the per-unit improvements from Units 1 and 2) \222\ from LNB
and SOFA with SCR is 2.759 dv at the most impacted Class I area, with
incremental visibility improvements of 1.29 dv and 0.932 dv over LNB
and SOFA and LNB and SOFA with SNCR, respectively. These visibility
improvements are very much in line with those at Cholla, and given that
the incremental cost-effectiveness of SCR at Huntington Unit 1 is still
reasonable, the comparison with Cholla also supports selection of SCR
for Huntington Unit 1. We invite comment on other potentially relevant
BART determinations and our methodology generally.
---------------------------------------------------------------------------

    \221\ 77 FR 42834 (July 20, 2012) (proposal); 77 FR 72512,
72514-15 (Dec. 5, 2012) (final).
    \222\ We use the source-wide number here to compare with the
Cholla determination; in addition as explained above we must
consider source-wide visibility improvements.
---------------------------------------------------------------------------

    Based on these comparisons, we think LNB and SOFA with SCR is very
cost-effective at $2,515/ton, and provides substantial visibility
benefits at several Class I areas. For example, the visibility
improvement from that control option is 1.488 dv at Arches NP, 1.881 dv
at Canyonlands NP, and 1.108 dv at Capitol Reef NP. The incremental
cost-effectiveness of SCR, $4,879/ton, is by comparison with the
Laramie River Station BART determination also reasonable. This
comparison also shows that costs are justified in light of the
substantial visibility benefits, both total and incremental.
    In the case of Huntington, the unit level visibility improvements
justify the most stringent level of control, SCR, for each of the two
Huntington units. Necessarily, when we consider the source-wide
visibility improvements, they will be larger and also justify the most
stringent level of control.
    Accordingly, for Huntington Unit 1, we propose to find that BART
for NOX is LNB and SOFA with SCR, represented by an emission
limit of 0.07 lb/MMBtu (30-day rolling average). The proposed BART
emission limit of 0.07 lb/MMBtu allows for a sufficient margin of
compliance for a 30-day rolling average limit that would apply at all
times, including startup, shutdown, and malfunction.\223\ We are also
proposing monitoring, recordkeeping, and reporting requirements as
described in our proposed regulatory text for 40 CFR 52.2336.
---------------------------------------------------------------------------

    \223\ Emission limits such as BART are required to be met on a
continuous basis. See 70 FR 39104, 39172 (July 6, 2005) (stating
that emissions limits including BART are to be met on a ``continuous
basis'' in the BART Guidelines, section V); 42 U.S.C. 7602(k)
(noting that emission limits are to be on ``a continuous basis'').
---------------------------------------------------------------------------

    Under 40 CFR 51.308(e)(1)(iv), ``each source subject to BART [is]
required to install and operate BART as expeditiously as practicable,
but in no event later than 5 years after approval of the implementation
plan revision.'' In light of the considerable effort involved to
retrofit SCR, we propose that five years is as expeditiously as
practicable. Therefore, we propose a compliance deadline of five years
from the date our final FIP becomes effective.
b. Huntington Unit 2
    Generally, Huntington Unit 2 is identical to Unit 1. The Huntington
Unit 2 boiler is of tangential-fired design with newer generation low-
NOX burners and separated overfire air which were installed
in winter 2006. Huntington Unit 2 currently achieves an annual emission
rate of approximately 0.21 lb/MMBtu with these combustion controls.
Under Utah's submitted regional haze SIP, Unit 2 is subject to a state-
law NOX emission limit of 0.26 lb/MMBtu on a 30-day rolling
average. Prior to the installation of LNB and SOFA the unit operated
with an actual annual emission rate of about 0.39 lb/MMBtu.
Step 1: Identify All Available NOX Control Technologies
    For the same reasons as for Huntington Unit 1, we propose to adopt
the identification of available NOX control technologies in
PacifiCorp's 2012 BART analysis to satisfy Step 1, and we refer the
reader to the 2012 PacifiCorp BART analysis for details on the
available NOX control technologies.
Step 2: Eliminate Technically Infeasible Options
    In its 2012 BART analysis,\224\ PacifiCorp eliminated available
NOX control technologies that PacifiCorp evaluated as
technologically infeasible for Huntington Unit 2. The remaining
technologically feasible control technologies are the combustion

controls, LNB and SOFA, and the post-combustion controls, SNCR and SCR.
---------------------------------------------------------------------------

    \224\ PacifiCorp BART Analysis for Huntington Unit 2, pp. 2.a-
106--2.a-124 (2012).
---------------------------------------------------------------------------

    We agree with PacifiCorp's evaluation of technologically available
controls for Huntington Unit 2 and propose to adopt it for Step 2.
Step 3: Evaluate Control Effectiveness of Remaining Control
Technologies
    As noted previously, Huntington Unit 2 is currently achieving an
actual annual emission rate of approximately 0.21 lb/MMBtu with LNB and
SOFA. This represents a 44.6 percent reduction from the baseline
emission rate of 0.39 lb/MMBtu.
    The post-combustion control technologies, SNCR and SCR, have been
evaluated in combination with combustion controls. That is, the inlet
concentration to the post-combustion controls is assumed to be 0.21 lb/
MMBtu (annual). This allows the equipment and operating and maintenance
costs of the post-combustion controls to be minimized based on the
lower inlet NOX concentration.
    Typically, SNCR reduces NOX an additional 20 to 30
percent above combustion controls without excessive NH3
slip.\225\ For this analysis, the control efficiency of SNCR has been
calculated based on the formula in the 2015 draft CCM SNCR
chapter,\226\ which for Huntington Unit 2 yields an additional
reduction of 21.5 percent after combustion controls. When combined with
LNB and SOFA, SNCR is anticipated to achieve an annual emission rate of
0.17 lb/MMBtu, corresponding to an overall control efficiency of 56.6
percent.
---------------------------------------------------------------------------

    \225\ Institute of Clean Air Companies, White Paper, SNCR for
Controlling NOX Emissions, pp. 4 and 9 (Feb. 2008).
    \226\ EPA Selective Noncatalytic, Reduction Cost Manual Draft
for Public Comment, p. 1-6 (Figure 1.1c: SNCR NOX
Reduction Efficiency Versus Baseline NOX Levels for Coal-
fired Utility Boilers) (June 5, 2015).
---------------------------------------------------------------------------

    SCR can achieve performance emission rates as low as 0.04 to 0.07
lb/MMBtu on an annual basis.\227\ For this analysis, consistent with
our actions elsewhere, as well with PacifiCorp's analysis, we use an
annual emission rate of 0.05 lb/MMBtu for SCR, which when combined with
LNB and SOFA achieves an overall control efficiency of 87.0 percent.
---------------------------------------------------------------------------

    \227\ Srivastava, R., Hall, R., Khan, S., Lani, B., & Culligan,
K., Nitrogen Oxides Emission Control Options for Coal-Fired Utility
Boilers, 55 J. Air & Waste Mgmt Assoc. 55, 1367, 1367-88 (2005).
---------------------------------------------------------------------------

    A summary of emissions projections for the control options
evaluated is provided in Table 31.

                Table 31--Summary of NOX BART Analysis Control Technologies for Huntington Unit 2
----------------------------------------------------------------------------------------------------------------
                                                      Control         Annual         Emissions       Remaining
                 Control option                    effectiveness   emission rate     reduction       emissions
                                                        (%)         (lb/MMBtu)         (tpy)           (tpy)
----------------------------------------------------------------------------------------------------------------
LNB/SOFA +SCR...................................            87.0            0.05           5,023             747
LNB/SOFA +SNCR..................................            56.6            0.17           3,264           2,506
LNB/SOFA........................................            44.6            0.21           2,576           3,194
Baseline\1\.....................................              --            0.39              --           5,770
----------------------------------------------------------------------------------------------------------------
\1\ Baseline emissions were determined by averaging the annual emissions from 2001 to 2003 as reported to EPA
  Air Markets Program Data available at http://ampd.epa.gov/ampd/.

Step 4: Evaluate Impacts and Document Results
Part 1--Costs of Compliance
    We obtained capital costs for LNB and SOFA from the 2014 PacifiCorp
BART analysis. PacifiCorp did not report any operating and maintenance
costs for LNB and SOFA. Similarly, we obtained capital cost estimates
for LNB and SOFA with SNCR from the 2014 PacifiCorp BART analysis.
However, for operating and maintenance costs we propose to rely on the
draft 2015 draft SNCR chapter of the CCM. Refer to the ATP report for
details. Capital costs for LNB and SOFA with SCR were also obtained
from the 2014 PacifiCorp BART analysis. However, PacifiCorp's capital
costs were adjusted to account for items that were double-counted or
should not be allowed under the CCM, such as AFUDC.\228\ In addition,
the capital costs were adjusted to account for a significant
overestimation of the catalyst volume and related costs. These
adjustments are documented in the ATP report and associated spread
sheet. A discussion of operating and maintenance costs of SCR is also
included in the ATP report. For the reasons given in the report, we
propose to adopt the cost estimates contained in it.
---------------------------------------------------------------------------

    \228\ See 79 FR 5032, 5133 (discussing reasons for rejecting use
of AFUDC).
---------------------------------------------------------------------------

    A summary of our proposed cost estimates for all control options is
presented in Table 32.

                                                Table 32--Summary of NOX BART Costs on Huntington Unit 2
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Emissions     Average cost
                     Control option                        Total capital     Indirect      Direct annual   Total annual     reductions     effectiveness
                                                            investment     annual costs        costs           cost            (tpy)          ($/ton)
--------------------------------------------------------------------------------------------------------------------------------------------------------
LNB/SOFA................................................           $9.4M           $0.9M             $0M           $0.9M           2,576            $365
LNB/SOFA/SNCR...........................................           16.7M            1.6M            1.9M            3.5M           3,264           1,075
LNB/SOFA/SCR............................................          109.4M           10.4M            2.4M           12.9M           5,023           2,563
--------------------------------------------------------------------------------------------------------------------------------------------------------

Parts 2 and 3--Energy and Non-Air Quality Environmental Impacts of
Compliance
    The energy and non-air quality impacts for Huntington Unit 2 are
nearly identical to those for Huntington Unit 1 as discussed
previously. Accordingly, for the same reasons as for Huntington Unit 1,
we propose to determine that we have adequately considered these
impacts by including cost of additional energy in cost effectiveness
and assessing non-air quality environmental impacts as insufficient to
eliminate or weigh against any of the BART options.

Part 4--Remaining Useful Life
    PacifiCorp assumes a remaining useful life of at least 20 years for
Huntington Unit 2 in its BART analysis, and has not indicated any
intention to retire, or curtail generation from, Huntington Unit 2.
Therefore, this factor does not preclude any of the control options
considered. In addition, this factor does not impact our BART
calculation of cost effectiveness because annualized costs have been
calculated over a 20 year period for each of the control options
considered. We propose that this gives adequate consideration to this
factor.
Step 5: Evaluate Visibility Impacts
    Table 33 presents the highest of the 98th percentile visibility
improvements at the affected Class I areas for the three meteorological
years modeled, 2001 through 2003. Tables 34 and 35 present the number
of days (summed across three years) with impacts greater than the
contribution and causation thresholds--0.5 dv and 1.0 dv, respectively.

                              Table 33--Huntington Unit 2--Visibility Improvements
----------------------------------------------------------------------------------------------------------------
                                                                                LNB with SOFA   LNB with SOFA
                          Class I Area                             LNB with SOFA     and SNCR         and SCR
                                                                    ([Delta]dv)     ([Delta]dv)     ([Delta]dv)
----------------------------------------------------------------------------------------------------------------
Arches NP.......................................................           0.625           0.816           1.316
Black Canyon of the Gunnison NP.................................           0.143           0.184           0.292
Bryce Canyon NP.................................................           0.205           0.266           0.424
Canyonlands NP..................................................           0.776           1.016           1.657
Capitol Reef NP.................................................           0.449           0.584           0.955
Flat Tops WA....................................................           0.168           0.217           0.343
Grand Canyon NP.................................................           0.183           0.236           0.371
Mesa Verde NP...................................................           0.199           0.258           0.414
Zion NP.........................................................           0.136           0.176           0.281
----------------------------------------------------------------------------------------------------------------

                           Table 34--Huntington Unit 2--Days Greater Than 0.5 Deciview
                                               [Three year total]
----------------------------------------------------------------------------------------------------------------
                                                                                LNB with SOFA
                  Class I Area                       Baseline      LNB with SOFA     and SNCR      LNB with SOFA
                                                      (days)          (days)          (days)      and SCR (days)
----------------------------------------------------------------------------------------------------------------
Arches NP.......................................             237             223             214             186
Black Canyon of the Gunnison NP.................              45              35              32              26
Bryce Canyon NP.................................              36              26              26              23
Canyonlands NP..................................             277             254             244             220
Capitol Reef NP.................................             131             119             116             104
Flat Tops WA....................................              64              44              39              31
Grand Canyon NP.................................              40              36              35              30
Mesa Verde NP...................................              63              48              43              31
Zion NP.........................................              21              17              16              15
----------------------------------------------------------------------------------------------------------------

                           Table 35--Huntington Unit 2--Days Greater Than 1.0 Deciview
                                               [Three year total]
----------------------------------------------------------------------------------------------------------------
                                                                                LNB with SOFA
                  Class I Area                       Baseline      LNB with SOFA     and SNCR      LNB with SOFA
                                                      (days)          (days)          (days)      and SCR (days)
----------------------------------------------------------------------------------------------------------------
Arches NP.......................................             146             122             118              98
Black Canyon of the Gunnison NP.................              16               8               7               4
Bryce Canyon NP.................................              19              15              13               6
Canyonlands NP..................................             175             153             149             126
Capitol Reef NP.................................              91              75              70              59
Flat Tops WA....................................              17               9               8               4
Grand Canyon NP.................................              19              13              13               9
Mesa Verde NP...................................              22              13              13               6
Zion NP.........................................              11               8               6               4
----------------------------------------------------------------------------------------------------------------

    Select BART.
    A summary of our impacts analysis for Huntington Unit 2 is
presented in Table 36.

                                                 Table 36--Summary of Huntington Unit 2 Impacts Analysis
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                      Annual                                                                              Visibility impacts *
                                     emission     Emission      Total      Average cost     Incremental cost   -----------------------------------------
          Control option            rate (lb/    reduction      annual     effectiveness    effectiveness ($/     Improvement    Days  >0.5   Days  >1.0
                                      MMBtu)       (tpy)      costs ($)       ($/ton)             ton)               (dv)            dv           dv
--------------------------------------------------------------------------------------------------------------------------------------------------------
LNB with SOFA....................         0.21        2,576        $0.9M            $365  ....................           0.776          254          153
LNB with SOFA and SNCR...........         0.17        3,264         3.5M           1,075  $3,730..............           1.016          244          149
LNB with SOFA and SCR............         0.05        5,023        12.9M           2,563  $5,326..............           1.657          220          126
                                                                                (compared to LNB
                                                                                with SOFA and SNCR).
                                                                                $4,877 (compared to
                                                                                LNB with SOFA).
--------------------------------------------------------------------------------------------------------------------------------------------------------
* At the most impacted Class I area, Canyonlands National Park.

    In determining what to co-propose as BART, we have taken into
consideration all five of the statutory factors required by the CAA:
The costs of compliance, the energy and non-air quality environmental
impacts of compliance, any existing pollution control technology in use
at the source, the remaining useful life of the source, and the degree
of improvement in visibility which may reasonably be anticipated to
result from the use of such technology. Later on we provide a
justification for our selection of BART, including an explanation of
how each of the CAA factors was used in that selection.
    We have considered the energy and non-air quality environmental
impacts of compliance and propose to find that they do not appreciably
favor one control option over another, or preclude a particular control
option from selection. The existing pollution controls have been
accounted for in our evaluation of BART, and also would not favor or
preclude any of the control options considered. And finally, we have
considered the remaining useful life of the source and find that it is
sufficiently long (greater than 20 years) so as not to favor or
preclude any of the control options. As a result, the remaining
factors--the costs of compliance and visibility improvement--are the
primary factors that lead us to our proposed BART selection for
Huntington Unit 2.
    In order to select BART we propose to weigh the costs of compliance
against visibility impacts by generally comparing them with BART
determinations that have been made elsewhere. Specifically, we propose
to compare the average cost-effectiveness, incremental cost-
effectiveness, visibility improvement, and incremental visibility
improvement for LNB and SOFA with SCR with BART determinations where
the EPA and States have based their determination on the same metrics.
The most comparable determinations are the same as for Huntington Unit
1: The Laramie River Station, Hayden Station, and Cholla Power Plant
determinations.
    Based on these comparisons, we think LNB and SOFA with SCR is very
cost-effective at $2,563/ton, and provides substantial visibility
benefits at several Class I areas. For example, the visibility
improvement from that control option is 1.316 at Arches NP and 1.657 dv
Canyonlands NP. The incremental cost-effectiveness of SCR, $5,326/ton,
is by comparison also reasonable. This comparison also shows that costs
are justified in light of the substantial visibility benefits, both
total and incremental.
    In the case of Huntington, the unit level visibility improvements
justify the most stringent level of control, SCR, for each of the two
Huntington units. Necessarily, when we consider the source-wide
visibility improvements, they will be larger and also justify the most
stringent level of control. In addition, the unit level visibility
improvements and source-wide visibility improvements at other impacted
Class I areas, particularly Arches NP and Capitol Reef NP, support the
most stringent level of control.
    Accordingly, for Huntington Unit 2, we propose to find that BART
for NOX is LNB and SOFA with SCR, represented by an emission
limit of 0.07 lb/MMBtu (30-day rolling average). The proposed BART
emission limit of 0.07 lb/MMBtu allows for a sufficient margin of
compliance for a 30-day rolling average limit that would apply at all
times, including startup, shutdown, and malfunction.\229\ We are also
proposing monitoring, recordkeeping, and reporting requirements as
described in our proposed regulatory text for 40 CFR 52.2336.
---------------------------------------------------------------------------

    \229\ Emission limits such as BART are required to be met on a
continuous basis. See 70 FR 39104, 39172 (July 6, 2005) (stating
that emissions limits including BART are to be met on a ``continuous
basis'' in the BART Guidelines, section V); 42 U.S.C. 7602(k)
(noting that emission limits are to be on ``a continuous basis'').
---------------------------------------------------------------------------

    Under Sec.  51.308(e)(1)(iv), ``each source subject to BART [is]
required to install and operate BART as expeditiously as practicable,
but in no event later than 5 years after approval of the implementation
plan revision.'' In light of the considerable effort involved to
retrofit SCR, we propose that five years is as expeditiously as
practicable. Therefore, we propose a compliance deadline of five years
from the date our final FIP becomes effective.
4. Federal Monitoring, Recordkeeping, and Reporting
    We have explained earlier in section III.C.4 that the CAA and 40
CFR part 51, subpart K require that SIPs, including the regional haze
SIP, contain certain elements sufficient to ensure emission limits are
practically enforceable. EPA is proposing to disapprove Utah's
NOX BART Alternative along with the associated monitoring,
recordkeeping and reporting requirements in SIP sections IX.H.21 and
H.22. EPA is proposing regulatory language as part of our FIP that
specifies monitoring, recordkeeping, and reporting requirements for all
BART sources. For purposes of consistency, EPA is proposing to adopt
language that is the same as we have adopted for other states in Region
8.

E. PM10 BART Determinations

    As discussed earlier in section IV.B.2, Utah determined that the
PM10 BART emission limit for Hunter Units 1 and 2 and
Huntington Units 1 and 2 was 0.015 lb/MMBtu based on a three-run test
average. Utah noted that because the most stringent technology is in
place at

these units and that the PM10 emission limits have been made
enforceable in the SIP, no further analysis was required.
    EPA has reviewed Utah's PM10 BART streamlined five-
factor analysis and PM10 BART determinations for Hunter
Units 1 and 2 and Huntington Units 1 and 2 and proposes to find that
these determinations meet the requirements of 40 CFR 51.309(d)(4)(vii).
The fabric filter baghouses installed at these BART units are
considered the most stringent technology available. The emission limit
of 0.015 lb/MMBtu at these units represents the most stringent emission
limit for PM10 and is within the range of PM10
BART limits that EPA has approved in other states.\230\ Utah's use of a
streamlined approach to the five-factor analysis is reasonable as the
BART Guidelines provide that a comprehensive BART analysis can be
avoided if a source commits to a BART determination that consists of
the most stringent controls available.\231\
---------------------------------------------------------------------------

    \230\ For example, Wyoming, Naughton Unit 3, Jim Bridger Units 1
through 4, Dave Johnston Units 3 and 4, and Wyodak Unit 1. See 40
CFR 52.2636; 79 FR 5220, (Jan. 30, 2014).
    \231\ 40 CFR 51, appendix Y, section IV.D.1.9.
---------------------------------------------------------------------------

    Utah's regulatory text provides, ``[e]missions of particulate (PM)
shall not exceed 0.015 lb/MMBtu heat input from each boiler based on a
3-run test average.'' \232\ It further states that ``[s]tack testing
for the emission limitation shall be performed each year on each
boiler.'' \233\ We note that BART limits must apply at all times.\234\
Furthermore, EPA's credible evidence rule requires that a state's plan
must not preclude the use of any credible evidence or information,
which can include evidence and information other than the test method
specified in the plan, that would indicate whether a source was in
compliance with applicable requirements.\235\
---------------------------------------------------------------------------

    \232\ Utah Regional Haze State Implementation Plan: Emission
Limits & Operating Practices, Sections IX.H.22.a.i.A-B,
IX.H.22.b.i.A-B (2015).
    \233\ Id.
    \234\ See 42 U.S.C. 7602(k); 40 CFR part 51, appendix Y, section
V.
    \235\ 40 CFR 51.212(c).
---------------------------------------------------------------------------

    Consistent with these requirements, we propose to interpret Utah's
regulatory text as imposing a PM10 limit of 0.015 lb/MMBtu
that applies at all times and does not preclude the use, including the
exclusive use, of any credible evidence or information, relevant to
whether a source is in compliance with the limit.

F. Consultation With FLMs

    As discussed previously in section IV.G, Utah conducted FLM
consultation during late 2014, providing over 60 days prior to the
December 1, 2014 public hearing. Subsequently, the National Park
Service provided extensive comments in response to a second public
comment period in April 2015. Based on these considerations, we propose
to find that Utah has met the requirements of 40 CFR 308(i)(2).

VII. EPA's Proposed Actions

    EPA is proceeding with co-proposals on Utah's June 3, 2015 and
October 20, 2015 regional haze SIP revisions. Later on is a summary of
our proposed actions. As noted above, EPA intends to finalize only one
proposal, although it may differ from what is presented here based on
any comments and additional information we receive.

A. Proposed Approval

    We are proposing to approve the regional haze SIP revisions
submitted by the State of Utah on June 3, 2015 and October 20, 2015:
    1. We are proposing to approve these aspects of the State's June 4,
2015, which rely on elements from prior approvals \236\:
---------------------------------------------------------------------------

    \236\ As necessary for our proposed approval, we propose to fill
gaps in the 2015 Utah RH SIP submittals with the following already-
approved sections from the 2011 Utah RH SIP: Section XX.B.8, Figures
1 and 2, Affected Class I Areas, pp. 8-9; Section XX.D.6.b, Table 3,
BART-Eligible Sources in Utah, p. 21; Section. XX.D.6.c, Sources
Subject to BART, pp. 21-23.
---------------------------------------------------------------------------

     NOX BART Alternative that includes
NOX, and SO2, emission reductions from Hunter
Units 1 through 3, Huntington 1 and 2, and Carbon Units 1 and 2, and
PM10 emission reductions from Carbon Units 1 and 2.
     BART determinations and emission limits for
PM10 at Hunter Units 1 and 2 and Huntington Units 1 and 2.
     Monitoring, recordkeeping and reporting requirements for
units subject to the BART Alternative and the PM10 emission
limits, including conditional approval of the recordkeeping
requirements for the PM10 emission limits.
    2. We are proposing to approve these elements of the State's
October 20, 2015 SIP submittal:
     Enforceable commitments to revise, at a minimum, SIP
Section XX.D.3.c and State rule R307-150 by March 2018 to clarify
emission inventory requirements for tracking compliance with the
SO2 milestone and properly accounting for the SO2
emission reductions due to the closure of the Carbon plant.

B. Proposed Partial Disapproval/Approval and Federal Implementation
Plan

    1. We are proposing to approve these elements of the State's SIP
submittals, which rely on elements from prior approvals:\237\
---------------------------------------------------------------------------

    \237\ Id.
---------------------------------------------------------------------------

     BART determinations and emission limits for
PM10 at Hunter Units 1 and 2 and Huntington Units 1 and 2.
     Monitoring, recordkeeping, and reporting requirements for
units subject to the PM10 emission limits, including
conditional approval of the recordkeeping requirements for the
PM10 emission limits.
    2. We are proposing to disapprove these aspects of the State's June
4, 2015 SIP:
     NOX BART Alternative that includes
NOX, and SO2, emission reductions from Hunter
Units 1 through 3, Huntington 1 and 2, and Carbon Units 1 and 2, and
PM10 emission reductions from Carbon Units 1 and 2.
     Monitoring, recordkeeping and reporting requirements for
units subject to the BART Alternative.
     The enforceable commitments to revise, at a minimum, SIP
Section XX.D.3.c and State rule R307-150 by March 2018.
    3. We are proposing that if we finalize our co-proposal to
disapprove the NOX BART Alternative, we will promulgate a
FIP to address the deficiencies in the Utah regional haze SIPs. The
proposed FIP includes the following elements:
     NOX BART determinations and limits for Hunter
Units 1 and 2, Huntington Units 1 and 2.
     Monitoring, recordkeeping, and reporting requirements
applicable to Hunter Units 1 and 2, and Huntington Units 1 and 2.

VIII. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review and Executive
Order 13563: Improving Regulation and Regulatory Review

    This action is not a ``significant regulatory action'' under the
terms of Executive Order 12866 \238\ and was therefore not submitted to
the Office of Management and Budget (OMB) for review. This proposed
rule applies to only two facilities containing four BART units. It is
therefore not a rule of general applicability.
---------------------------------------------------------------------------

    \238\ 58 FR 51735, 51738 (Oct. 4, 1993).
---------------------------------------------------------------------------

B. Paperwork Reduction Act

    This proposed action does not impose an information collection
burden under the provisions of the Paperwork Reduction Act (PRA).\239\
Because this proposed rule applies to just two facilities, the PRA does
not apply.
---------------------------------------------------------------------------

    \239\ 44 U.S.C. 3501 et seq.

---------------------------------------------------------------------------

C. Regulatory Flexibility Act

    The Regulatory Flexibility Act (RFA) generally requires an agency
to prepare a regulatory flexibility analysis of any rule subject to
notice and comment rulemaking requirements under the Administrative
Procedure Act or any other statute unless the agency certifies that the
rule will not have a significant economic impact on a substantial
number of small entities. Small entities include small businesses,
small organizations, and small governmental jurisdictions.
    For purposes of assessing the impacts of this proposed rule on
small entities, small entity is defined as: (1) A small business as
defined by the Small Business Administration's (SBA) regulations at 13
CFR 121.201; (2) a small governmental jurisdiction that is a government
of a city, county, town, school district or special district with a
population of less than 50,000; and (3) a small organization that is
any not-for-profit enterprise which is independently owned and operated
and is not dominant in its field.
    After considering the economic impacts of this proposed rule on
small entities, I certify that this action will not have a significant
economic impact on a substantial number of small entities under the
RFA. This rule does not impose any requirements or create impacts on
small entities as small entities are not subject to the requirements of
this rule. Under the full approval approach in this proposed rule, EPA
would approve all elements of the State's submittals as meeting the
federal regional haze requirements and therefore EPA's action does not
impose any requirements.\240\ Under the partial approval approach, EPA
would disapprove the state's SIP submittal and promulgate a FIP that
consists of imposing federal controls to meet the BART requirement for
emissions on four specific BART units at two facilities in Utah. The
net result of this action is that EPA is proposing direct emission
controls on selected units at only two sources, and those sources are
large electric generating plants that are not owned by small entities,
and therefore the owners are not a small entities under the RFA.
---------------------------------------------------------------------------

    \240\ See, e.g., Mid-Tex Elec. Coop., Inc. v. FERC, 773 F.2d 327
(D.C. Cir. 1985) (hereinafter Mid-Tex).
---------------------------------------------------------------------------

D. Unfunded Mandates Reform Act (UMRA)

    Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), Public
Law 104-4, establishes requirements for federal agencies to assess the
effects of their regulatory actions on State, local, and Tribal
governments and the private sector. Under section 202 of UMRA, EPA
generally must prepare a written statement, including a cost-benefit
analysis, for final rules with ``Federal mandates'' that may result in
expenditures to State, local, and Tribal governments, in the aggregate,
or to the private sector, of $100 million or more (adjusted for
inflation) in any one year. Before promulgating an EPA rule for which a
written statement is needed, section 205 of UMRA generally requires EPA
to identify and consider a reasonable number of regulatory alternatives
and adopt the least costly, most cost-effective, or least burdensome
alternative that achieves the objectives of the rule. The provisions of
section 205 of UMRA do not apply when they are inconsistent with
applicable law. Moreover, section 205 of UMRA allows EPA to adopt an
alternative other than the least costly, most cost-effective, or least
burdensome alternative if the Administrator publishes with the final
rule an explanation why that alternative was not adopted. Before EPA
establishes any regulatory requirements that may significantly or
uniquely affect small governments, including Tribal governments, it
must have developed under section 203 of UMRA a small government agency
plan. The plan must provide for notifying potentially affected small
governments, enabling officials of affected small governments to have
meaningful and timely input in the development of EPA regulatory
actions with significant federal intergovernmental mandates, and
informing, educating, and advising small governments on compliance with
the regulatory requirements.
    Under Title II of UMRA, EPA has determined that this proposed rule
does not contain a federal mandate that may result in expenditures that
exceed the inflation-adjusted UMRA threshold of $100 million \241\ by
State, local, or Tribal governments or the private sector in any one
year. The private sector expenditures that would result from the
approach to promulgate a FIP would include BART controls for all four
units at the Hunter and Huntington plants would be $51.5 million \242\
per year. Additionally, we do not foresee significant costs (if any)
for state and local governments. Thus, because the annual expenditures
associated with the approach to promulgate a FIP are less than the
threshold of $100 million in any one year, this proposed rule is not
subject to the requirements of sections 202 or 205 of UMRA. This
proposed rule is also not subject to the requirements of section 203 of
UMRA because it contains no regulatory requirements that might
significantly or uniquely affect small governments.
---------------------------------------------------------------------------

    \241\ Adjusted to 2014 dollars, the UMRA threshold becomes $152
million.
    \242\ Andover Technology Partners, Cost of NOX BART
Controls on Utah EGUs, to EC/R, Inc. (Oct. 22, 2015).Andover
Technology Partners is a subcontractor to EC/R Incorporated.
---------------------------------------------------------------------------

E. Executive Order 13132: Federalism

    Executive Order 13132, Federalism,\243\ revokes and replaces
Executive Orders 12612 (Federalism) and 12875 (Enhancing the
Intergovernmental Partnership). Executive Order 13132 requires EPA to
develop an accountable process to ensure ``meaningful and timely input
by State and local officials in the development of regulatory policies
that have federalism implications.'' \244\ ``Policies that have
federalism implications'' is defined in the Executive Order to include
regulations that have ``substantial direct effects on the States, on
the relationship between the national government and the States, or on
the distribution of power and responsibilities among the various levels
of government.'' \245\ Under Executive Order 13132, EPA may not issue a
regulation ``that has federalism implications, that imposes substantial
direct compliance costs, . . . and that is not required by statute,
unless [the federal government provides the] funds necessary to pay the
direct [compliance] costs incurred by the State and local
governments,'' or EPA consults with state and local officials early in
the process of developing the final regulation.\246\ EPA also may not
issue a regulation that has federalism implications and that preempts
state law unless the Agency consults with state and local officials
early in the process of developing the final regulation.
---------------------------------------------------------------------------

    \243\ 64 FR 43255, 43255-43257 (Aug. 10, 1999).
    \244\ 64 FR 43255, 43257.
    \245\ Id.
    \246\ Id.
---------------------------------------------------------------------------

    This action does not have federalism implications. Neither of the
two approaches presented in this proposed rule will have substantial
direct effects on the states, on the relationship between the national
government and the states, or on the distribution of power and
responsibilities among the various levels of government, as specified
in Executive Order 13132. Under the full approval approach, this
proposed action would merely approve the state SIP as federally
enforceable. Under the partial approval approach, this proposed action
would merely address the State not fully meeting its

obligation under the CAA to adequately address the visibility
requirements of Part C of Title I of the CAA in its SIP and to prohibit
emissions from interfering with other states measures to protect
visibility. Thus, Executive Order 13132 does not apply to this action.

F. Executive Order 13175: Consultation and Coordination With Indian
Tribal Governments

    Executive Order 13175, entitled ``Consultation and Coordination
with Indian Tribal Governments'', requires EPA to develop an
accountable process to ensure ``meaningful and timely input by tribal
officials in the development of regulatory policies that have tribal
implications.'' \247\ This proposed rule does not have tribal
implications, as specified in Executive Order 13175. It will not have
substantial direct effects on tribal governments. Thus, Executive Order
13175 does not apply to this rule.
---------------------------------------------------------------------------

    \247\ 65 FR 67249, 67250 (Nov. 9, 2000).
---------------------------------------------------------------------------

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

    This action is not subject to Executive Order 13045 (62 FR 19885,
April 23, 1997) because the environmental health or safety risks
addressed by this action do not present a disproportionate risk to
children. Note, however, that emissions reductions achieved as a result
of this rule, under either proposal, will have a positive benefit on
children's health, as they are especially vulnerable to impacts from
emissions.

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

    This action is not subject to Executive Order 13211 (66 FR 28355
(May 22, 2001)), because it is not a significant regulatory action
under Executive Order 12866.

I. National Technology Transfer and Advancement Act

    Section 12 of the National Technology Transfer and Advancement Act
(NTTAA) of 1995 requires Federal agencies to evaluate existing
technical standards when developing a new regulation. Section 12(d) of
NTTAA, Public Law 104-113, 12(d) (15 U.S.C. 272 note) directs EPA to
consider and use ``voluntary consensus standards'' in its regulatory
activities unless to do so would be inconsistent with applicable law or
otherwise impractical. Voluntary consensus standards are technical
standards (e.g., materials specifications, test methods, sampling
procedures, and business practices) that are developed or adopted by
voluntary consensus standards bodies. NTTAA directs EPA to provide
Congress, through OMB, explanations when the Agency decides not to use
available and applicable voluntary consensus standards.
    This proposed rulemaking does not involve technical standards.
Therefore, EPA is not considering the use of any voluntary consensus
standards.

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

    Executive Order 12898, establishes federal executive policy on
environmental justice.\248\ Its main provision directs federal
agencies, to the greatest extent practicable and permitted by law, to
make environmental justice part of their mission by identifying and
addressing, as appropriate, disproportionately high and adverse human
health or environmental effects of their programs, policies, and
activities on minority populations and low-income populations in the
United States.
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    \248\ 59 FR 7629, 7629 (Feb. 16, 1994).
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    I certify that the approaches under this proposed rule will not
have potential disproportionately high and adverse human health or
environmental effects on minority, low-income or indigenous/tribal
populations. The results of this evaluation are available in the
docket. Both approaches would result in overall emission reductions for
NOX, SO2 and PM10 and therefore an
increase in the level of environmental protection for all affected
populations. EPA, however, will consider any input received during the
public comment period regarding environmental justice considerations.

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

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Incorporation by
reference, Intergovernmental relations, Nitrogen dioxide, Particulate
matter, Sulfur oxides.

    Dated: December 16, 2015.
Shaun L. McGrath,
Regional Administrator, Region 8.

    For the reasons discussed in the preamble, the Environmental
Protection Agency proposes to amend 40 CFR part 52 as follows:

PART 52--APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS

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

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

Subpart TT--Utah

0
2. Add Sec.  52.2336 to read as follows:

Sec.  52.2336  Federal implementation plan for regional haze.

    (a) Applicability. (1) This section applies to each owner and
operator of the following emissions units in the State of Utah:
    (i) PacifiCorp Hunter Plant Units 1 and 2; and
    (ii) PacifiCorp Huntington Plant Units 1 and 2.
    (b) Definitions. Terms not defined here shall have the meaning
given them in the Clean Air Act or EPA's regulations implementing the
Clean Air Act. For purposes of this section:
    (1) BART means Best Available Retrofit Technology.
    (2) BART unit means any unit subject to a Regional Haze emission
limit in table 1 of this section.
    (3) Continuous emission monitoring system or CEMS means the
equipment required by this section to sample, analyze, measure, and
provide, by means of readings recorded at least once every 15 minutes
(using an automated data acquisition and handling system (DAHS)), a
permanent record of NOX emissions, diluent, or stack gas
volumetric flow rate.
    (4) FIP means Federal Implementation Plan.
    (5) The term lb/MMBtu means pounds per million British thermal
units of heat input to the fuel-burning unit.
    (6) NOX means nitrogen oxides.
    (7) Operating day means a 24-hour period between 12 midnight and
the following midnight during which any fuel is combusted at any time
in the BART unit. It is not necessary for fuel to be combusted for the
entire 24-hour period.
    (8) The owner/operator means any person who owns or who operates,
controls, or supervises a unit identified in paragraph (a) of this
section.
    (9) Unit means any of the units identified in paragraph (a) of this
section.
    (c) Emissions limitations. (1) The owners/operators of emissions
units subject to this section shall not emit, or cause to be emitted,
NOX in excess of the following limitations:

       Table 1--to Sec.   52.2336--Emission Limits for BART Units
------------------------------------------------------------------------
                                                           NOX emission
                                                            limit--lb/
                  Source name/BART unit                   MMBtu  (30-day
                                                              rolling
                                                             average)
------------------------------------------------------------------------
PacifiCorp Hunter Plant/Unit 1 \1\......................            0.07
PacifiCorp Hunter Plant/Unit 2 \1\......................            0.07
PacifiCorp Huntington Plant/Unit 1 \1\..................            0.07
PacifiCorp Huntington Plant/Unit 2 \1\..................            0.07
------------------------------------------------------------------------
\1\ The owners and operators of PacifiCorp Hunter Units 1 and 2 and
  Huntington Units 1 and 2, shall comply with the NOX emission limit for
  BART of 0.07 lb/MMBtu and other requirements of this section by [date
  five years from the effective date of the final rule].

    (2) These emission limitations shall apply at all times, including
startups, shutdowns, emergencies, and malfunctions.
    (d) Compliance date. (1) The owners and operators of PacifiCorp
Hunter Units 1 and 2 shall comply with the NOX emission
limit of 0.07 lb/MMBtu and other requirements of this section by [date
five years from the effective date of the final rule]. The owners and
operators of PacifiCorp Huntington Units 1 and 2 shall comply with the
NOX emission limit of 0.07 lb/MMBtu and other requirements
of this section by [date five years from the effective date of the
final rule].
    (e) Compliance determinations for NOX. (1) For all BART
units:
    (i) CEMS. At all times after the earliest compliance date specified
in paragraph (d) of this section, the owner/operator of each unit shall
maintain, calibrate, and operate a CEMS, in full compliance with the
requirements found at 40 CFR part 75, to accurately measure
NOX, diluent, and stack gas volumetric flow rate from each
unit. The CEMS shall be used to determine compliance with the emission
limitations in paragraph (c) of this section for each unit.
    (ii) Method. (A) For any hour in which fuel is combusted in a unit,
the owner/operator of each unit shall calculate the hourly average
NOX emission rate in lb/MMBtu at the CEMS in accordance with
the requirements of 40 CFR part 75. At the end of each operating day,
the owner/operator shall calculate and record a new 30-day rolling
average emission rate in lb/MMBtu from the arithmetic average of all
valid hourly emission rates from the CEMS for the current operating day
and the previous 29 successive operating days.
    (B) An hourly average NOX emission rate in lb/MMBtu is
valid only if the minimum number of data points, as specified in 40 CFR
part 75, is acquired by both the pollutant concentration monitor
(NOX) and the diluent monitor (O2 or
CO2).
    (C) Data reported to meet the requirements of this section shall
not include data substituted using the missing data substitution
procedures of subpart D of 40 CFR part 75, nor shall the data have been
bias adjusted according to the procedures of 40 CFR part 75.
    (f) Recordkeeping. The owner/operator shall maintain the following
records for at least five years:
    (1) All CEMS data, including the date, place, and time of sampling
or measurement; parameters sampled or measured; and results.
    (2) Records of quality assurance and quality control activities for
emissions measuring systems including, but not limited to, any records
required by 40 CFR part 75.
    (3) Records of all major maintenance activities conducted on
emission units, air pollution control equipment, and CEMS.
    (4) Any other CEMS records required by 40 CFR part 75.
    (g) Reporting. All reports under this section shall be submitted to
the Director, Office of Enforcement, Compliance and Environmental
Justice, U.S. Environmental Protection Agency, Region 8, Mail Code
8ENF-AT, 1595 Wynkoop Street, Denver, Colorado 80202-1129.
    (1) The owner/operator of each unit shall submit quarterly excess
emissions reports for NOX BART units no later than the 30th
day following the end of each calendar quarter. Excess emissions means
emissions that exceed the emissions limits specified in paragraph (c)
of this section. The reports shall include the magnitude, date(s), and
duration of each period of excess emissions, specific identification of
each period of excess emissions that occurs during startups, shutdowns,
and malfunctions of the unit, the nature and cause of any malfunction
(if known), and the corrective action taken or preventative measures
adopted.
    (2) The owner/operator of each unit shall submit quarterly CEMS
performance reports, to include dates and duration of each period
during which the CEMS was inoperative (except for zero and span