Document ID: EPA-R08-OAR-2012-0026-0082
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2013-01-08T05:00Z

December 13, 2012
     Summary of EPA's Revised Additional Visibility Improvement Modeling
                          for Wyoming's 309(g) SIP 
      In response to comments on its proposal, EPA has performed new CALPUFF visibility modeling using revised baseline emissions rates.  All Region 8 modeling files are available upon request. Contact Laurel Dygowski at dygowski.laurel@epa.gov. 
      As explained in our proposed notice, EPA had previously performed additional modeling of NOx control scenarios for both BART and reasonable progress sources. This modeling was performed to ascertain visibility improvements from individual NOx controls that the State and BART sources had not individually evaluated. For baseline emissions, the BART Guidelines recommend that states use the maximum 24-hour average actual emission rate for the meteorological period being modeled.  The visibility modeling performed by PacifiCorp, and subsequently submitted by the State, deviates from this guidance by using the permit limit emission rates and maximum rated heat input to derive the modeled emission rates instead of the actual maximum 24-hour average. The visibility modeling performed by Basin Electric, and subsequently submitted by the State, also deviates from this guidance by using a baseline hourly emission rates derived from actual annual average heat input (MMBtu) and actual annual average emission rates (lb/MMBtu) from 2001-2003 continuous emissions monitoring (CEM) data.   For consistency, EPA's previously completed additional modeling used the State's baseline emission rates for the PacifiCorp sites and Basin Electric's Laramie River Station. All other aspects of EPA's additional visibility modeling followed the recommendations made in the State of Wyoming Department of Environmental Quality (WY DEQ) BART Air Modeling Protocol. In response to comments that EPA should have followed the WY DEQ BART Air Modeling Protocol for its additional modeling, EPA has now performed new modeling using the maximum 24-hour average actual emission rates. The results of this new modeling are summarized in this document.
           Tables 3 through 11 show the CALPUFF inputs used for each unit modeled. EPA's modeling modified the State of Wyoming's inputs in order to isolate the impact of different NOx control scenarios.  As seen in the tables, the NOx emission rates were varied across the different scenarios with the other input parameters held constant.  For the PacifiCorp and Basin Electric BART sources, the inputs were derived from the State of Wyoming's BART Application Analyses that can be downloaded from the following website: http://deq.state.wy.us/aqd/309(g)%20Attachment%20A_January%202011%20Submittal.asp
EPA's modeling utilized the emission and stack parameter CALPUFF inputs from "Post-Control Scenario A" in the State's? reports for its Scenarios 1-3 with the only difference between scenarios being the emission rate for NOx and, in the SCR scenarios, total sulfate rates were increased to account for the additional production of ??? that results from SCR controls.  EPA's "New Baseline" is essentially the State's "Post-Control Scenario A" but with the NOx emission rate from their "Baseline" scenario.  Table 1 summarizes the control scenarios from EPA's additional modeling for BART sources.
Table 1- Description of EPA control scenarios for Wyoming's BART sources
                                 EPA Scenario
                                  Description
New Baseline
Post-Control Scenario A from State`s BART Application Analysis with NOx emission rate from state's "Baseline" scenario
Scenario 1
Post-Control Scenario A from State's BART Application Analysis with NOx emission rate that reflects the visibility improvement from LNB/OFA controls.
Scenario 2
Post-Control Scenario A from State's BART Application Analysis with NOx emission rate that reflects the visibility improvement from SNCR controls
Scenario 3
Post-Control Scenario A from State's BART Application Analysis with NOx emission rate that reflects the visibility improvement from SCR controls

      EPA also performed additional modeling for Dave Johnston's Units 1 and 2 (see Table 12 and Table 13).  These are considered reasonable progress sources and were not part of the State's BART Application Analyses.  For consistency, EPA followed a similar approach for modeling these sources as used for the BART sources.  Permit limit emission rates with heat input were used to derive emission inputs in the "New Baseline" scenario.  Similar to the BART sources, the only differences in the control scenarios are the emission rates for NOx and, in the SCR scenario (Scenario 3), total sulfate rates were increased to account for the additional production  that results from SCR controls. Stack parameter data for these sources was obtained from the Western Region Air Partnership's (WRAP) 2002 SMOKE input files.  Table 2 summarizes the control scenarios for EPA's reasonable progress source modeling.
      Table 14 through Table 17 present the results of the additional visibility modeling for all units at each subject facility. Using the updated CALPUFF output, the 98[th] percentile or 8[th] maximum 24-hour visibility impact (deciview [Δdv]) was determined at all Class I areas within 300 kilometers of the subject facility for each year between 2001 and 2003. These tables also present the visibility improvements for EPA Scenario 1, Scenario 2, and Scenario 3, which was determined by the difference between the New Baseline and EPA Scenario. 
Table 2  -  Description of EPA control scenarios for Reasonable Progress sources (Dave Johnston Units 1 and 2)
                                 EPA Scenario
                                  Description
New Baseline
Inputs obtained from facility's Title V Operating Permit limits
Scenario 1
Same inputs as New Baseline with a NOx emission rate that reflect visibility improvements from LNB/OFA controls
Scenario 2
Same inputs as New Baseline with a NOx emission rate that reflect visibility improvements from SNCR controls
Scenario 3
Same inputs as New Baseline with a NOx emission rate that reflect visibility improvements from SCR controls

Table 3  -  Modeling Assumptions for PacifiCorp - Dave Johnston Unit 3
CALPUFF Inputs
New Baseline
Scenario 1
Scenario 2
Scenario 3
SO2 (lb/hr)
                                                                            420
                                                                            420
                                                                            420
                                                                            420
Total Sulfate (SO4)(lb/hr)
                                                                            2.5
                                                                            2.5
                                                                            2.5
                                                                            5.1
Nox (lb/hr)
                                                                         1671.0
                                                                          706.3
                                                                          529.7
                                                                          163.3
HNO3
                                                                              0
                                                                              0
                                                                              0
                                                                              0
NO3
                                                                              0
                                                                              0
                                                                              0
                                                                              0
PM10-2.5 
(coarse PM)(lb/hr)
                                                                           23.9
                                                                           23.9
                                                                           23.9
                                                                           23.9
PM2.5 (lb/hr)
                                                                           18.1
                                                                           18.1
                                                                           18.1
                                                                           18.1
Stack Height (meters)
                                                                          152.4
                                                                          152.4
                                                                          152.4
                                                                          152.4
Base Elevation (meters)
                                                                           1509
                                                                           1509
                                                                           1509
                                                                           1509
Stack Diameter (meters)
                                                                           4.57
                                                                           4.57
                                                                           4.57
                                                                           4.57
Exit Velocity (meters/second)
                                                                           25.5
                                                                           25.5
                                                                           25.5
                                                                           25.5
Exit Temperature (Kelvin)
                                                                            348
                                                                            348
                                                                            348
                                                                            348

Table 4  -  Modeling Assumptions for PacifiCorp - Dave Johnston Unit 4
CALPUFF Inputs
New Baseline
Scenario 1
Scenario 2
Scenario 3
SO2 (lb/hr)
                                                                            615
                                                                            615
                                                                            615
                                                                            615
Total Sulfate (SO4)(lb/hr)
                                                                            3.7
                                                                            3.7
                                                                            3.7
                                                                            7.4
Nox (lb/hr)
                                                                         1983.0
                                                                          765.1
                                                                          612.1
                                                                          270.8
HNO3
                                                                              0
                                                                              0
                                                                              0
                                                                              0
NO3
                                                                              0
                                                                              0
                                                                              0
                                                                              0
PM10-2.5 
(coarse PM)(lb/hr)
                                                                           35.1
                                                                           35.1
                                                                           35.1
                                                                           35.1
PM2.5 (lb/hr)
                                                                           26.4
                                                                           26.4
                                                                           26.4
                                                                           26.4
Stack Height (meters)
                                                                            152
                                                                            152
                                                                            152
                                                                            152
Base Elevation (meters)
                                                                           1509
                                                                           1509
                                                                           1509
                                                                           1509
Stack Diameter (meters)
                                                                           5.79
                                                                           5.79
                                                                           5.79
                                                                           5.79
Exit Velocity (meters/second)
                                                                           25.7
                                                                           25.7
                                                                           25.7
                                                                           25.7
Exit Temperature (Kelvin)
                                                                            350
                                                                            350
                                                                            350
                                                                            350

Table 5  -  Modeling Assumptions for PacifiCorp - Naughton Unit 1
CALPUFF Inputs
New Baseline
Scenario 1
Scenario 2
Scenario 3
SO2 (lb/hr)
                                                                            278
                                                                            278
                                                                            278
                                                                            278
Total Sulfate (SO4)(lb/hr)
                                                                           16.7
                                                                           16.7
                                                                           16.7
                                                                           33.3
Nox (lb/hr)
                                                                         1322.0
                                                                          540.7
                                                                          405.5
                                                                          128.2
HNO3
                                                                              0
                                                                              0
                                                                              0
                                                                              0
NO3
                                                                              0
                                                                              0
                                                                              0
                                                                              0
PM10-2.5 
(coarse PM)(lb/hr)
                                                                           33.4
                                                                           33.4
                                                                           33.4
                                                                           33.4
PM2.5 (lb/hr)
                                                                           44.3
                                                                           44.3
                                                                           44.3
                                                                           44.3
Stack Height (meters)
                                                                            145
                                                                            145
                                                                            145
                                                                            145
Base Elevation (meters)
                                                                           2115
                                                                           2115
                                                                           2115
                                                                           2115
Stack Diameter (meters)
                                                                           4.88
                                                                           4.88
                                                                           4.88
                                                                           4.88
Exit Velocity (meters/second)
                                                                           18.1
                                                                           18.1
                                                                           18.1
                                                                           18.1
Exit Temperature (Kelvin)
                                                                            323
                                                                            323
                                                                            323
                                                                            323

Table 6  -  Modeling Assumptions for PacifiCorp - Naughton Unit 2
CALPUFF Inputs
New Baseline
Scenario 1
Scenario 2
Scenario 3
SO2 (lb/hr)
                                                                            360
                                                                            360
                                                                            360
                                                                            360
Total Sulfate (SO4)(lb/hr)
                                                                           21.6
                                                                           21.6
                                                                           21.6
                                                                           43.2
Nox (lb/hr)
                                                                         1636.0
                                                                          660.7
                                                                          495.5
                                                                          156.7
HNO3
                                                                              0
                                                                              0
                                                                              0
                                                                              0
NO3
                                                                              0
                                                                              0
                                                                              0
                                                                              0
PM10-2.5 
(coarse PM)(lb/hr)
                                                                           55.7
                                                                           55.7
                                                                           55.7
                                                                           55.7
PM2.5 (lb/hr)
                                                                           73.9
                                                                           73.9
                                                                           73.9
                                                                           73.9
Stack Height (meters)
                                                                            145
                                                                            145
                                                                            145
                                                                            145
Base Elevation (meters)
                                                                           2115
                                                                           2115
                                                                           2115
                                                                           2115
Stack Diameter (meters)
                                                                           5.49
                                                                           5.49
                                                                           5.49
                                                                           5.49
Exit Velocity (meters/second)
                                                                           18.5
                                                                           18.5
                                                                           18.5
                                                                           18.5
Exit Temperature (Kelvin)
                                                                            323
                                                                            323
                                                                            323
                                                                            323

Table 7  -  Modeling Assumptions for PacifiCorp - Naughton Unit 3
CALPUFF Inputs
New Baseline
Scenario 1
Scenario 2
Scenario 3
SO2 (lb/hr)
                                                                            814
                                                                            814
                                                                            814
                                                                            814
Total Sulfate (SO4)(lb/hr)
                                                                           33.3
                                                                           33.3
                                                                           33.3
                                                                           66.6
Nox (lb/hr)
                                                                         2368.0
                                                                         2137.4
                                                                         1496.2
                                                                          323.9
HNO3
                                                                              0
                                                                              0
                                                                              0
                                                                              0
NO3
                                                                              0
                                                                              0
                                                                              0
                                                                              0
PM10-2.5 
(coarse PM)(lb/hr)
                                                                           23.9
                                                                           23.9
                                                                           23.9
                                                                           23.9
PM2.5 (lb/hr)
                                                                           31.6
                                                                           31.6
                                                                           31.6
                                                                           31.6
Stack Height (meters)
                                                                            145
                                                                            145
                                                                            145
                                                                            145
Base Elevation (meters)
                                                                           2113
                                                                           2113
                                                                           2113
                                                                           2113
Stack Diameter (meters)
                                                                           8.08
                                                                           8.08
                                                                           8.08
                                                                           8.08
Exit Velocity (meters/second)
                                                                           20.2
                                                                           20.2
                                                                           20.2
                                                                           20.2
Exit Temperature (Kelvin)
                                                                            322
                                                                            322
                                                                            322
                                                                            322

Table 8  -  Modeling Assumptions for PacifiCorp  -  Wyodak
CALPUFF Inputs
New Baseline
Scenario 1
Scenario 2
Scenario 3
SO2 (lb/hr)
                                                                            759
                                                                            759
                                                                            759
                                                                            759
Total Sulfate (SO4)(lb/hr)
                                                                            5.5
                                                                            5.5
                                                                            5.5
                                                                           11.6
Nox (lb/hr)
                                                                         1397.0
                                                                         1022.0
                                                                          817.6
                                                                          266.4
HNO3
                                                                              0
                                                                              0
                                                                              0
                                                                              0
NO3
                                                                              0
                                                                              0
                                                                              0
                                                                              0
PM10-2.5 
(coarse PM)(lb/hr)
                                                                           70.5
                                                                           70.5
                                                                           70.5
                                                                           70.5
PM2.5 (lb/hr)
                                                                           40.2
                                                                           40.2
                                                                           40.2
                                                                           40.2
Stack Height (meters)
                                                                            122
                                                                            122
                                                                            122
                                                                            122
Base Elevation (meters)
                                                                           1347
                                                                           1347
                                                                           1347
                                                                           1347
Stack Diameter (meters)
                                                                            6.1
                                                                            6.1
                                                                            6.1
                                                                            6.1
Exit Velocity (meters/second)
                                                                           23.5
                                                                           23.5
                                                                           23.5
                                                                           23.5
Exit Temperature (Kelvin)
                                                                            350
                                                                            350
                                                                            350
                                                                            350

Table 9  -  Modeling Assumptions for Basin Electric  -  Laramie River Station Unit 1
CALPUFF Inputs
New Baseline
Scenario 1
Scenario 2
Scenario 3
SO2 (tpy)
                                                                           3745
                                                                           3745
                                                                           3745
                                                                           3745
Total Sulfate (SO4)(tpy)
                                                                           3.06
                                                                           3.18
                                                                           3.18
                                                                           3.18
Nox (tpy)
                                                                        9557.16
                                                                         7099.1
                                                                         5679.1
                                                                         1848.8
HNO3
                                                                              0
                                                                              0
                                                                              0
                                                                              0
NO3
                                                                              0
                                                                              0
                                                                              0
                                                                              0
PM10-2.5 
(coarse PM)(tpy)
                                                                              0
                                                                              0
                                                                              0
                                                                              0
PM2.5 (tpy)
                                                                            702
                                                                            702
                                                                            702
                                                                            702
Stack Height (meters)
                                                                        184.404
                                                                        184.404
                                                                        184.404
                                                                        184.404
Base Elevation (meters)
                                                                           1348
                                                                           1348
                                                                           1348
                                                                           1348
Stack Diameter (meters)
                                                                         8.6868
                                                                         8.6868
                                                                         8.6868
                                                                         8.6868
Exit Velocity (meters/second)
                                                                         21.336
                                                                         21.336
                                                                         21.336
                                                                         21.336
Exit Temperature (Kelvin)
                                                                       338.7056
                                                                       338.7056
                                                                       338.7056
                                                                       338.7056

Table 10  -  Modeling Assumptions for Basin Electric  -  Laramie River Station Unit 2
CALPUFF Inputs
New Baseline
Scenario 1
Scenario 2
Scenario 3
SO2 (tpy)
                                                                           3725
                                                                           3725
                                                                           3725
                                                                           3725
Total Sulfate (SO4)(tpy)
                                                                            2.8
                                                                           3.25
                                                                           3.25
                                                                           3.25
Nox (tpy)
                                                                         8786.3
                                                                         6240.6
                                                                         4992.8
                                                                         1625.0
HNO3
                                                                              0
                                                                              0
                                                                              0
                                                                              0
NO3
                                                                              0
                                                                              0
                                                                              0
                                                                              0
PM10-2.5 
(coarse PM)(tpy)
                                                                              0
                                                                              0
                                                                              0
                                                                              0
PM2.5 (tpy)
                                                                            698
                                                                            698
                                                                            698
                                                                            698
Stack Height (meters)
                                                                        184.404
                                                                        184.404
                                                                        184.404
                                                                        184.404
Base Elevation (meters)
                                                                           1348
                                                                           1348
                                                                           1348
                                                                           1348
Stack Diameter (meters)
                                                                         8.6868
                                                                         8.6868
                                                                         8.6868
                                                                         8.6868
Exit Velocity (meters/second)
                                                                          21.03
                                                                          21.03
                                                                          21.03
                                                                          21.03
Exit Temperature (Kelvin)
                                                                       338.7056
                                                                       338.7056
                                                                       338.7056
                                                                       338.7056

Table 11  -  Modeling Assumptions for Basin Electric  -  Laramie River Station Unit 3
CALPUFF Inputs
New Baseline
Scenario 1
Scenario 2
Scenario 3
SO2 (tpy)
                                                                           4060
                                                                           4060
                                                                           4060
                                                                           4060
Total Sulfate (SO4)(tpy)
                                                                           0.22
                                                                           0.22
                                                                           0.22
                                                                           0.22
Nox (tpy)
                                                                         8834.5
                                                                         6354.9
                                                                         5083.9
                                                                         1654.8
HNO3
                                                                              0
                                                                              0
                                                                              0
                                                                              0
NO3
                                                                              0
                                                                              0
                                                                              0
                                                                              0
PM10-2.5 (coarse PM)(tpy)
                                                                              0
                                                                              0
                                                                              0
                                                                              0
PM2.5 (tpy)
                                                                            716
                                                                            716
                                                                            716
                                                                            716
Stack Height (meters)
                                                                        184.404
                                                                        184.404
                                                                        184.404
                                                                        184.404
Base Elevation (meters)
                                                                           1348
                                                                           1348
                                                                           1348
                                                                           1348
Stack Diameter (meters)
                                                                         8.6868
                                                                         8.6868
                                                                         8.6868
                                                                         8.6868
Exit Velocity (meters/second)
                                                                          22.25
                                                                          22.25
                                                                          22.25
                                                                          22.25
Exit Temperature (Kelvin)
                                                                          352.0
                                                                          352.0
                                                                          352.0
                                                                          352.0

Reasonable Progress Sources 
Table 12  -  Modeling Assumptions for PacifiCorp - Dave Johnston Unit 1
CALPUFF Inputs
New Baseline
Scenario 1
Scenario 2
Scenario 3
SO2 (lb/hr)
                                                                           1620
                                                                           1620
                                                                           1620
                                                                              0
Total Sulfate (SO4)(lb/hr)
                                                                              1
                                                                              1
                                                                              1
                                                                              2
Nox (lb/hr)
                                                                          679.6
                                                                          298.8
                                                                          224.1
                                                                           74.7
HNO3
                                                                              0
                                                                              0
                                                                              0
                                                                              0
NO3
                                                                              0
                                                                              0
                                                                              0
                                                                              0
PM10-2.5 
(coarse PM)(lb/hr)
                                                                        149.726
                                                                        149.726
                                                                        149.726
                                                                        149.726
PM2.5 (lb/hr)
                                                                        198.474
                                                                        198.474
                                                                        198.474
                                                                        198.474
Stack Height (meters)
                                                                          152.4
                                                                          152.4
                                                                          152.4
                                                                          152.4
Base Elevation (meters)
                                                                           1509
                                                                           1509
                                                                           1509
                                                                           1509
Stack Diameter (meters)
                                                                           3.35
                                                                           3.35
                                                                           3.35
                                                                           3.35
Exit Velocity (meters/second)
                                                                          28.35
                                                                          28.35
                                                                          28.35
                                                                          28.35
Exit Temperature (Kelvin)
                                                                         418.15
                                                                         418.15
                                                                         418.15
                                                                         418.15

Table 13  -  Modeling Assumptions for PacifiCorp - Dave Johnston Unit 2
CALPUFF Inputs
New Baseline
Scenario 1
Scenario 2
Scenario 3
SO2 (lb/hr)
                                                                           1620
                                                                           1620
                                                                           1620
                                                                           1620
Total Sulfate (SO4)(lb/hr)
                                                                              1
                                                                              1
                                                                              1
                                                                              2
Nox (lb/hr)
                                                                          653.7
                                                                          296.7
                                                                          222.5
                                                                           74.2
HNO3
                                                                               
                                                                               
                                                                               
                                                                               
NO3
                                                                               
                                                                               
                                                                               
                                                                               
PM10-2.5 
(coarse PM)(lb/hr)
                                                                        149.726
                                                                        149.726
                                                                        149.726
                                                                        149.726
PM2.5 (lb/hr)
                                                                        198.474
                                                                        198.474
                                                                        198.474
                                                                        198.474
Stack Height (meters)
                                                                          152.4
                                                                          152.4
                                                                          152.4
                                                                          152.4
Base Elevation (meters)
                                                                           1509
                                                                           1509
                                                                           1509
                                                                           1509
Stack Diameter (meters)
                                                                           3.35
                                                                           3.35
                                                                           3.35
                                                                           3.35
Exit Velocity (meters/second)
                                                                          28.69
                                                                          28.69
                                                                          28.69
                                                                          28.69
Exit Temperature (Kelvin)
                                                                         425.93
                                                                         425.93
                                                                         425.93
                                                                         425.93

Table 14  -  Model Results for PacifiCorp  -  Dave Johnston Units
Unit 
Class I Area
by Year
                                 New Baseline
                                  Scenario 1
                                  Scenario 2
                                  Scenario 3

                                98th Percentile
                           Visibility Impact (∆dv)
                                98th Percentile
                           Visibility Impact (∆dv)
                        Visibility Improvement (∆dv)
                                98th Percentile
                           Visibility Impact (∆dv)
                        Visibility Improvement (∆dv)
                                98th Percentile
                           Visibility Impact (∆dv)
                        Visibility Improvement (∆dv)
Unit 1
Badlands 2001
                                     0.824
                                     0.659
                                     0.165
                                     0.631
                                     0.193
                                     0.578
                                     0.246

Badlands 2002
                                     0.585
                                     0.490
                                     0.095
                                     0.462
                                     0.123
                                     0.419
                                     0.166

Badlands 2003
                                     0.773
                                     0.659
                                     0.114
                                     0.618
                                     0.155
                                     0.539
                                     0.234

Wind Cave 2001
                                     0.921
                                     0.717
                                     0.204
                                     0.683
                                     0.238
                                     0.622
                                     0.299

Wind Cave 2002
                                     0.879
                                     0.769
                                     0.110
                                     0.741
                                     0.138
                                     0.686
                                     0.193

Wind Cave 2003
                                     1.226
                                     0.918
                                     0.308
                                     0.874
                                     0.352
                                     0.787
                                     0.439
Unit 2
Badlands 2001
                                     0.802
                                     0.658
                                     0.144
                                     0.631
                                     0.171
                                     0.577
                                     0.225

Badlands 2002
                                     0.590
                                     0.487
                                     0.103
                                     0.460
                                     0.130
                                     0.422
                                     0.168

Badlands 2003
                                     0.774
                                     0.659
                                     0.115
                                     0.617
                                     0.157
                                     0.538
                                     0.236

Wind Cave 2001
                                     0.904
                                     0.701
                                     0.203
                                     0.676
                                     0.228
                                     0.630
                                     0.274

Wind Cave 2002
                                     0.875
                                     0.763
                                     0.112
                                     0.736
                                     0.139
                                     0.683
                                     0.192

Wind Cave 2003
                                     1.206
                                     0.918
                                     0.288
                                     0.873
                                     0.333
                                     0.788
                                     0.418
Unit 3
Badlands 2001
                                     0.800
                                     0.417
                                     0.383
                                     0.350
                                     0.450
                                     0.211
                                     0.589

Badlands 2002
                                     0.641
                                     0.310
                                     0.331
                                     0.250
                                     0.391
                                     0.152
                                     0.489

Badlands 2003
                                     0.882
                                     0.440
                                     0.442
                                     0.359
                                     0.523
                                     0.208
                                     0.674

Wind Cave 2001
                                     1.03
                                     0.529
                                     0.500
                                     0.435
                                     0.594
                                     0.238
                                     0.791

Wind Cave 2002
                                     0.84
                                     0.448
                                     0.395
                                     0.370
                                     0.473
                                     0.230
                                     0.613

Wind Cave 2003
                                     1.32
                                     0.683
                                     0.639
                                     0.564
                                     0.758
                                     0.318
                                     1.004

Mt Zirkel 2001
                                     0.216
                                     0.115
                                     0.101
                                     0.093
                                     0.123
                                     0.061
                                     0.155

Mt Zirkel 2002
                                     0.353
                                     0.177
                                     0.176
                                     0.148
                                     0.205
                                     0.096
                                     0.257

Mt Zirkel 2003
                                     0.439
                                     0.228
                                     0.211
                                     0.190
                                     0.249
                                     0.105
                                     0.334

Rawah 2001
                                     0.264
                                     0.147
                                     0.117
                                     0.122
                                     0.142
                                     0.07
                                     0.191

Rawah 2002
                                     0.486
                                     0.262
                                     0.224
                                     0.222
                                     0.264
                                     0.14
                                     0.349

Rawah 2003
                                     0.484
                                     0.241
                                     0.243
                                     0.197
                                     0.287
                                     0.11
                                     0.375

RMNP 2001
                                     0.311
                                     0.166
                                     0.145
                                     0.139
                                     0.172
                                     0.09
                                     0.224

RMNP 2002
                                     0.475
                                     0.230
                                     0.245
                                     0.189
                                     0.286
                                     0.09
                                     0.381

RMNP 2003
                                     0.688
                                     0.346
                                     0.342
                                     0.281
                                     0.407
                                     0.15
                                     0.539
Unit 4
Badlands 2001
                                     0.995
                                     0.456
                                     0.539
                                     0.456
                                     0.539
                                     0.320
                                     0.675

Badlands 2002
                                     0.762
                                     0.365
                                     0.397
                                     0.332
                                     0.430
                                     0.222
                                     0.540

Badlands 2003
                                     1.049
                                     0.556
                                     0.493
                                     0.479
                                     0.570
                                     0.322
                                     0.727

Mt Zirkel 2001
                                     0.242
                                     0.124
                                     0.118
                                     0.123
                                     0.119
                                     0.122
                                     0.120

Mt Zirkel 2002
                                     0.424
                                     0.216
                                     0.208
                                     0.189
                                     0.235
                                     0.165
                                     0.259

Mt Zirkel 2003
                                     0.557
                                     0.279
                                     0.278
                                     0.238
                                     0.319
                                     0.192
                                     0.365

Rawah 2001
                                     0.332
                                     0.163
                                     0.169
                                     0.139
                                     0.193
                                     0.100
                                     0.232

Rawah 2002
                                     0.586
                                     0.316
                                     0.270
                                     0.282
                                     0.304
                                     0.208
                                     0.378

Rawah 2003
                                     0.557
                                     0.270
                                     0.287
                                     0.235
                                     0.322
                                     0.169
                                     0.388

RMNP 2001
                                     0.373
                                     0.186
                                     0.187
                                     0.166
                                     0.207
                                     0.122
                                     0.251

RMNP 2002
                                     0.515
                                     0.264
                                     0.251
                                     0.236
                                     0.279
                                     0.149
                                     0.366

RMNP 2003
                                     0.869
                                     0.421
                                     0.448
                                     0.364
                                     0.505
                                     0.239
                                     0.630

Wind Cave 2001
                                     1.164
                                     0.469
                                     0.695
                                     0.468
                                     0.696
                                     0.349
                                     0.815

Wind Cave 2002
                                     1.079
                                     0.533
                                     0.546
                                     0.465
                                     0.614
                                     0.342
                                     0.737

Wind Cave 2003
                                     1.691
                                     0.853
                                     0.838
                                     0.745
                                     0.946
                                     0.478
                                     1.213

Table 15  -  Model Results for PacifiCorp  -  Naughton Units
Unit 
Class I Area
by Year
                                 New Baseline
                                  Scenario 1
                                  Scenario 2
                                  Scenario 3

                                98th Percentile
                           Visibility Impact (∆dv)
                                98th Percentile
                           Visibility Impact (∆dv)
                        Visibility Improvement (∆dv)
                                98th Percentile
                           Visibility Impact (∆dv)
                        Visibility Improvement (∆dv)
                                98th Percentile
                           Visibility Impact (∆dv)
                        Visibility Improvement (∆dv)
Unit 1
Bridger 2001
                                     1.634
                                     0.799
                                     0.835
                                     0.649
                                     0.985
                                     0.404
                                     1.230

Bridger 2002
                                     1.350
                                     0.675
                                     0.675
                                     0.557
                                     0.793
                                     0.368
                                     0.982

Bridger 2003
                                     1.490
                                     0.756
                                     0.734
                                     0.624
                                     0.866
                                     0.411
                                     1.079

Fitzpatrick 2001
                                     0.732
                                     0.349
                                     0.383
                                     0.283
                                     0.449
                                     0.174
                                     0.558

Fitzpatrick 2002
                                     0.481
                                     0.239
                                     0.242
                                     0.198
                                     0.283
                                     0.131
                                     0.350

Fitzpatrick 2003
                                     0.609
                                     0.304
                                     0.305
                                     0.248
                                     0.361
                                     0.155
                                     0.454

N. Absaroka 2001
                                     0.266
                                     0.129
                                     0.137
                                     0.109
                                     0.157
                                     0.073
                                     0.193

N. Absaroka 2002
                                     0.279
                                     0.141
                                     0.138
                                     0.120
                                     0.159
                                     0.083
                                     0.196

N. Absaroka 2003
                                     0.158
                                     0.079
                                     0.079
                                     0.068
                                     0.090
                                     0.048
                                     0.110

Washakie 2001
                                     0.327
                                     0.166
                                     0.161
                                     0.138
                                     0.189
                                     0.090
                                     0.237

Washakie 2002
                                     0.402
                                     0.205
                                     0.197
                                     0.172
                                     0.230
                                     0.112
                                     0.290

Washakie 2003
                                     0.291
                                     0.145
                                     0.146
                                     0.119
                                     0.172
                                     0.083
                                     0.208

Teton 2001
                                     0.408
                                     0.208
                                     0.200
                                     0.168
                                     0.240
                                     0.113
                                     0.295

Teton 2002
                                     0.477
                                     0.229
                                     0.248
                                     0.186
                                     0.291
                                     0.121
                                     0.356

Teton 2003
                                     0.331
                                     0.160
                                     0.171
                                     0.132
                                     0.199
                                     0.088
                                     0.243

Grand Teton 2001
                                     0.480
                                     0.230
                                     0.250
                                     0.188
                                     0.292
                                     0.124
                                     0.356

Grand Teton 2002
                                     0.665
                                     0.332
                                     0.333
                                     0.274
                                     0.391
                                     0.177
                                     0.488

Grand Teton 2003
                                     0.331
                                     0.161
                                     0.170
                                     0.131
                                     0.200
                                     0.098
                                     0.233

Yellowstone 2001
                                     0.392
                                     0.198
                                     0.194
                                     0.165
                                     0.227
                                     0.108
                                     0.284

Yellowstone 2002
                                     0.544
                                     0.267
                                     0.277
                                     0.219
                                     0.325
                                     0.137
                                     0.407

Yellowstone 2003
                                     0.339
                                     0.165
                                     0.174
                                     0.136
                                     0.203
                                     0.089
                                     0.250
Unit 2
Bridger 2001
                                     1.952
                                     0.983
                                     0.969
                                     0.804
                                     1.148
                                     0.531
                                     1.421

Bridger 2002
                                     1.575
                                     0.787
                                     0.788
                                     0.653
                                     0.922
                                     0.441
                                     1.134

Bridger 2003
                                     1.859
                                     0.956
                                     0.903
                                     0.796
                                     1.063
                                     0.543
                                     1.316

Fitzpatrick 2001
                                     0.853
                                     0.422
                                     0.431
                                     0.344
                                     0.509
                                     0.216
                                     0.637

Fitzpatrick 2002
                                     0.619
                                     0.299
                                     0.320
                                     0.249
                                     0.370
                                     0.163
                                     0.456

Fitzpatrick 2003
                                     0.709
                                     0.340
                                     0.369
                                     0.276
                                     0.433
                                     0.181
                                     0.528

N. Absaroka 2001
                                     0.347
                                     0.167
                                     0.180
                                     0.137
                                     0.210
                                     0.092
                                     0.255

N. Absaroka 2002
                                     0.344
                                     0.185
                                     0.159
                                     0.158
                                     0.186
                                     0.112
                                     0.232

N. Absaroka 2003
                                     0.193
                                     0.097
                                     0.096
                                     0.082
                                     0.111
                                     0.062
                                     0.131

Washakie 2001
                                     0.427
                                     0.217
                                     0.210
                                     0.175
                                     0.252
                                     0.124
                                     0.303

Washakie 2002
                                     0.484
                                     0.247
                                     0.237
                                     0.208
                                     0.276
                                     0.141
                                     0.343

Washakie 2003
                                     0.350
                                     0.174
                                     0.176
                                     0.145
                                     0.205
                                     0.101
                                     0.249

Teton 2001
                                     0.511
                                     0.261
                                     0.250
                                     0.215
                                     0.296
                                     0.146
                                     0.365

Teton 2002
                                     0.609
                                     0.294
                                     0.315
                                     0.241
                                     0.368
                                     0.161
                                     0.448

Teton 2003
                                     0.406
                                     0.202
                                     0.204
                                     0.169
                                     0.237
                                     0.108
                                     0.298

Grand Teton 2001
                                     0.603
                                     0.295
                                     0.308
                                     0.243
                                     0.360
                                     0.156
                                     0.447

Grand Teton 2002
                                     0.932
                                     0.458
                                     0.474
                                     0.375
                                     0.557
                                     0.234
                                     0.698

Grand Teton 2003
                                     0.421
                                     0.208
                                     0.213
                                     0.171
                                     0.250
                                     0.121
                                     0.300

Yellowstone 2001
                                     0.518
                                     0.262
                                     0.256
                                     0.219
                                     0.299
                                     0.146
                                     0.372

Yellowstone 2002
                                     0.536
                                     0.285
                                     0.251
                                     0.244
                                     0.292
                                     0.176
                                     0.360

Yellowstone 2003
                                     0.354
                                     0.172
                                     0.182
                                     0.142
                                     0.212
                                     0.095
                                     0.259
Unit 3
Bridger 2001
                                     2.222
                                     2.051
                                     0.171
                                     1.559
                                     0.663
                                     0.761
                                     1.461

Bridger 2002
                                     1.838
                                     1.695
                                     0.143
                                     1.291
                                     0.547
                                     0.694
                                     1.144

Bridger 2003
                                     2.391
                                     2.220
                                     0.171
                                     1.693
                                     0.698
                                     0.878
                                     1.513

Fitzpatrick 2001
                                     1.144
                                     1.057
                                     0.087
                                     0.816
                                     0.328
                                     0.400
                                     0.744

Fitzpatrick 2002
                                     0.896
                                     0.822
                                     0.074
                                     0.623
                                     0.273
                                     0.305
                                     0.591

Fitzpatrick 2003
                                     0.881
                                     0.810
                                     0.071
                                     0.612
                                     0.269
                                     0.279
                                     0.602

N. Absaroka 2001
                                     0.542
                                     0.499
                                     0.043
                                     0.380
                                     0.162
                                     0.188
                                     0.354

N. Absaroka 2002
                                     0.583
                                     0.541
                                     0.042
                                     0.423
                                     0.160
                                     0.221
                                     0.362

N. Absaroka 2003
                                     0.288
                                     0.266
                                     0.022
                                     0.205
                                     0.083
                                     0.115
                                     0.173

Washakie 2001
                                     0.808
                                     0.746
                                     0.062
                                     0.575
                                     0.233
                                     0.291
                                     0.517

Washakie 2002
                                     0.775
                                     0.712
                                     0.063
                                     0.542
                                     0.233
                                     0.267
                                     0.508

Washakie 2003
                                     0.589
                                     0.541
                                     0.048
                                     0.405
                                     0.184
                                     0.197
                                     0.392

Teton 2001
                                     0.858
                                     0.789
                                     0.069
                                     0.603
                                     0.255
                                     0.304
                                     0.554

Teton 2002
                                     0.962
                                     0.884
                                     0.078
                                     0.665
                                     0.297
                                     0.307
                                     0.655

Teton 2003
                                     0.609
                                     0.560
                                     0.049
                                     0.426
                                     0.183
                                     0.206
                                     0.403

Grand Teton 2001
                                     1.009
                                     0.932
                                     0.077
                                     0.723
                                     0.286
                                     0.362
                                     0.647

Grand Teton 2002
                                     1.090
                                     1.003
                                     0.087
                                     0.757
                                     0.333
                                     0.360
                                     0.730

Grand Teton 2003
                                     0.800
                                     0.734
                                     0.066
                                     0.547
                                     0.253
                                     0.266
                                     0.534

Yellowstone 2001
                                     0.834
                                     0.768
                                     0.066
                                     0.583
                                     0.251
                                     0.282
                                     0.552

Yellowstone 2002
                                     0.860
                                     0.791
                                     0.069
                                     0.600
                                     0.260
                                     0.292
                                     0.568

Yellowstone 2003
                                     0.451
                                     0.416
                                     0.035
                                     0.319
                                     0.132
                                     0.154
                                     0.297

Table 16  -  Model Results for PacifiCorp  -  Wyodak Units
Unit 
Class I Area
by Year
                                 New Baseline
                                  Scenario 1
                                  Scenario 2
                                  Scenario 3

                                98th Percentile
                           Visibility Impact (∆dv)
                                98th Percentile
                           Visibility Impact (∆dv)
                        Visibility Improvement (∆dv)
                                98th Percentile
                           Visibility Impact (∆dv)
                        Visibility Improvement (∆dv)
                                98th Percentile
                           Visibility Impact (∆dv)
                        Visibility Improvement (∆dv)
Unit 1
Badlands 2001
                                     0.579
                                     0.455
                                     0.124
                                     0.389
                                     0.190
                                     0.243
                                     0.336

Badlands 2002
                                     0.746
                                     0.613
                                     0.133
                                     0.539
                                     0.207
                                     0.299
                                     0.447

Badlands 2003
                                     0.706
                                     0.536
                                     0.170
                                     0.479
                                     0.227
                                     0.285
                                     0.421

Wind Cave 2001
                                     0.840
                                     0.648
                                     0.192
                                     0.558
                                     0.282
                                     0.322
                                     0.518

Wind Cave 2002
                                     0.958
                                     0.751
                                     0.207
                                     0.637
                                     0.321
                                     0.365
                                     0.593

Wind Cave 2003
                                     1.138
                                     0.896
                                     0.242
                                     0.762
                                     0.376
                                     0.431
                                     0.707

Table 17  -  Model Results for Basin Electric  -  Laramie River Station Units
Unit 
Class I Area
by Year
                                 New Baseline
                                  Scenario 1
                                  Scenario 2
                                  Scenario 3

                                98th Percentile
                           Visibility Impact (∆dv)
                                98th Percentile
                           Visibility Impact (∆dv)
                        Visibility Improvement (∆dv)
                                98th Percentile
                           Visibility Impact (∆dv)
                        Visibility Improvement (∆dv)
                                98th Percentile
                           Visibility Impact (∆dv)
                        Visibility Improvement (∆dv)
Unit 1
Badlands 2001
                                     1.278
                                     0.993
                                     0.285
                                     0.840
                                     0.438
                                     0.489
                                     0.789

Badlands 2002
                                     0.738
                                     0.582
                                     0.156
                                     0.504
                                     0.234
                                     0.297
                                     0.441

Badlands 2003
                                     1.051
                                     0.820
                                     0.231
                                     0.684
                                     0.367
                                     0.327
                                     0.724

Wind Cave 2001
                                     1.038
                                     0.838
                                     0.200
                                     0.721
                                     0.317
                                     0.399
                                     0.639

Wind Cave 2002
                                     1.077
                                     0.888
                                     0.189
                                     0.778
                                     0.299
                                     0.486
                                     0.591

Wind Cave 2003
                                     0.788
                                     0.618
                                     0.170
                                     0.531
                                     0.257
                                     0.331
                                     0.457

Rawah 2001
                                     0.322
                                     0.269
                                     0.053
                                     0.231
                                     0.091
                                     0.125
                                     0.197

Rawah 2002
                                     0.555
                                     0.454
                                     0.101
                                     0.395
                                     0.160
                                     0.239
                                     0.316

Rawah 2003
                                     0.351
                                     0.300
                                     0.051
                                     0.270
                                     0.081
                                     0.163
                                     0.188

RMNP 2001
                                     0.408
                                     0.318
                                     0.090
                                     0.267
                                     0.141
                                     0.154
                                     0.254

RMNP 2002
                                     0.603
                                     0.481
                                     0.122
                                     0.416
                                     0.187
                                     0.262
                                     0.341

RMNP 2003
                                     0.590
                                     0.472
                                     0.118
                                     0.404
                                     0.186
                                     0.219
                                     0.371
Unit 2
Badlands 2001
                                     1.194
                                     0.895
                                     0.299
                                     0.776
                                     0.418
                                     0.461
                                     0.733

Badlands 2002
                                     0.685
                                     0.532
                                     0.153
                                     0.464
                                     0.221
                                     0.284
                                     0.401

Badlands 2003
                                     0.974
                                     0.734
                                     0.240
                                     0.614
                                     0.360
                                     0.312
                                     0.662

Wind Cave 2001
                                     0.978
                                     0.769
                                     0.209
                                     0.666
                                     0.312
                                     0.377
                                     0.601

Wind Cave 2002
                                     1.031
                                     0.831
                                     0.200
                                     0.734
                                     0.297
                                     0.475
                                     0.556

Wind Cave 2003
                                     0.739
                                     0.562
                                     0.177
                                     0.498
                                     0.241
                                     0.321
                                     0.418

Rawah 2001
                                     0.307
                                     0.248
                                     0.059
                                     0.213
                                     0.094
                                     0.119
                                     0.188

Rawah 2002
                                     0.521
                                     0.417
                                     0.104
                                     0.366
                                     0.155
                                     0.229
                                     0.292

Rawah 2003
                                     0.327
                                     0.275
                                     0.052
                                     0.250
                                     0.077
                                     0.154
                                     0.173

RMNP 2001
                                     0.379
                                     0.287
                                     0.092
                                     0.242
                                     0.137
                                     0.147
                                     0.232

RMNP 2002
                                     0.580
                                     0.450
                                     0.130
                                     0.386
                                     0.194
                                     0.251
                                     0.329

RMNP 2003
                                     0.551
                                     0.429
                                     0.122
                                     0.370
                                     0.181
                                     0.203
                                     0.348
Unit 3
Badlands 2001
                                     1.141
                                     0.923
                                     0.218
                                     0.810
                                     0.331
                                     0.472
                                     0.669

Badlands 2002
                                     0.733
                                     0.577
                                     0.156
                                     0.493
                                     0.240
                                     0.299
                                     0.434

Badlands 2003
                                     0.896
                                     0.696
                                     0.200
                                     0.593
                                     0.303
                                     0.309
                                     0.587

Wind Cave 2001
                                     0.988
                                     0.787
                                     0.201
                                     0.683
                                     0.305
                                     0.389
                                     0.599

Wind Cave 2002
                                     0.993
                                     0.800
                                     0.193
                                     0.702
                                     0.291
                                     0.461
                                     0.532

Wind Cave 2003
                                     0.728
                                     0.583
                                     0.145
                                     0.496
                                     0.232
                                     0.336
                                     0.392

Rawah 2001
                                     0.314
                                     0.258
                                     0.056
                                     0.227
                                     0.087
                                     0.144
                                     0.170

Rawah 2002
                                     0.533
                                     0.432
                                     0.101
                                     0.380
                                     0.153
                                     0.241
                                     0.292

Rawah 2003
                                     0.348
                                     0.296
                                     0.052
                                     0.269
                                     0.079
                                     0.166
                                     0.182

RMNP 2001
                                     0.392
                                     0.301
                                     0.091
                                     0.255
                                     0.137
                                     0.162
                                     0.230

RMNP 2002
                                     0.584
                                     0.473
                                     0.111
                                     0.417
                                     0.167
                                     0.276
                                     0.308

RMNP 2003
                                     0.555
                                     0.438
                                     0.117
                                     0.379
                                     0.176
                                     0.220
                                     0.335