# Best Available Retrofit Technology (BART) Exemption Modeling Results

for the:



# ConocoPhillips Alaska Natural Gas Corporation (CPANGC) BART-Eligible Sources

prepared for:



# ConocoPhillips Alaska Inc.

prepared by:

April 2008

# Best Available Retrofit Technology (BART) Exemption Modeling Results for the ConocoPhillips Alaska Natural Gas Corporation (CPANGC) BART-Eligible Sources

April 2008

prepared for



# ConocoPhillips Alaska Inc. Anchorage, Alaska

prepared by

Hoefler Consulting Group

3401 Minnesota Dr., Suite 300

Anchorage, Alaska 99503 (907) 563-2137Page 1 

### Best Available Retrofit Technology (BART) Exemption Modeling Results for the ConocoPhillips Alaska Natural Gas Corporation (CPANGC) BART-Eligible Sources

Summary

With the enactment of the Regional Haze Rule, the United States Environmental Protection Agency (EPA) and state and local agencies have established a mechanism to address certain existing sources of air pollutant emissions that are shown to contribute to visibility impacts within Class I areas. This Best Available Retrofit Technology (BART) requirement applies to any BART-eligible source that ‘‘emits any air pollutant which may reasonably be anticipated to cause or contribute to any impairment of visibility” in any mandatory Class I area.

Under 40 Code of Federal Regulation (CFR) Part 51, Appendix Y (BART guideline), a BART-eligible source is considered to “contribute” to visibility impairment in a Class I area if the modeled change in deciviews is equal to or greater than the “contribution threshold.” Any BART-eligible source determined to cause or contribute to visibility impairment in any Class I area is subject to BART. Based on current regulatory guidance, a “contribution threshold” of 0.5 deciviews (dv) is the threshold at which modeled BART eligible source may contribute to visibility impairment.

A state has the option to exempt potentially BART-eligible sources from the BART requirements if a demonstration can be made that the source cannot reasonably cause or contribute to visibility impairment in a Cl ass I area. States, including Alaska, have established criteria and procedures for identifying BART-eligible sources. The Alaska Department of Environmental Conservation (ADEC) has developed regulations regarding BART-eligible sources (18 AAC 50.260, effective December 30, 2007).

ADEC has identified eleven CPANGC Alaska Kenai Liquefied Natural Gas (LNG) Plant emission units as being BART-eligible sources 1 

### . In accordance with 18 AAC 50.260, CPANGC has requested an exemption from BART regulations. The exemption request was based on the likelihood that dispersion modeling would demonstrate that the

emissions from the Kenai LNG Plant emission units would not cause or contribute to visibility impairment in any Class I area. A modeling protocol was submitted to ADEC in February 2008 and approved later that month.

The emissions from the Kenai LNG Plant BART-eligible emission units have been modeled. The modeling results at the Denali Class I area are less than the contribution

1 

### CPANGC acknowledges but disagrees with the identif ication of the Kenai LNG Plant as a source subject

to BART.Page 2 

### threshold of 0.5 dv. The modeling results are slightly above the contribution threshold at

the much closer Tuxedni Class I area.

Background

In 2007, the ADEC developed a list of Alaska BART-eligible sources based on the federal BART guidelines, conducted preliminary dispersion modeling of these BART-eligible sources, and released the results of a regional BART screening analysis that included all BART-eligible sources in the state.

The modeling was completed by the Western Regional Air Partnership (WRAP) on behalf of ADEC. The simulations were done using CALPUFF and a single year, 2002, of processed MM5 CALMET data. The simulations were performed to evaluate whether the BART-eligible sources were subject to a BART determination based on predicted impacts to visibility within two Alaska Class I areas, the Tuxedni National Wildlife Refuge designated as a National Wilderness Area (Tuxedni) and the Denali National Park including the Denali Wilderness but excluding Denali National Preserve (Denali). As noted above, BART-eligible sources are exempt from BART if the visibility impacts are belowscreening criteria set by ADEC, EPA, and the Federal Land Managers (FLMs). Nonexempt BART-eligible sources are potentially subject to costly additional pollution controls on the certain BART-eligible emission units.

WRAP used the CALPUFF modeling system to assess BART-eligible emission units based on the 15 kilometer (km) MM5 output data for 2002. The CALPUFF model grid spacing was 2 km, significantly different than the MM5 grid spacing of 15 km. In addition, because only one year was simulated, BART exemption simulations performed by WRAP used the highest modeled visib ility degradation, not the 98 th 

### percentile as allowed under EPA guidance.

Of the BART-eligible sources, twelve Kenai LNG Plant emission units were identified in the ADEC BART assessment as being BART-eligible sources based on definition and modeled visibility impact. Based on a requeste d review of BART-eligible sources, ADEC

removed one of the Kenai LNG Plant emission units from BART eligibility (May 7, 2007 letter from ADEC to Marta Czarnezki), leaving a total of eleven emission units potentially subject to BART.

Despite the ADEC modeling findings of significant impacts, CPANGC believed that these impacts are overly conservative, requested an exemption from BART, and submitted a modeling protocol to demonstrate that impacts from Kenai LNG Plant BART-eligible sources would not exceed threshold levels at the Class I areas, exempting the Kenai LNG

Plant emission units from BART.Page 3 

### Modeling Overview

The Kenai LNG Plant BART exemption modeling included the following elements:

• Three-years of Geomatrix-updated MM5 and processed CALMET files;

• The most recent EPA-approved version of CALPUFF (5.8);

• Daily maximum emission estimates;

• Exhaust parameters reflecting daily firing;

• Appropriate background values for ozone and ammonia; and

• Use of the 98 th 

### percentile visibility value to assess impact at both Tuxedni and

Denali.

During discussions with ADEC, the owners of many of the Alaska BART-eligible sources agreed to fund Geomatrix to develop two additional years of CALMET meteorological data, so that the appropriate 98 th 

### percentile values could be used in determining impacts within Class I areas. Geomatrix provided 3-years of processed CALMET data (2002 through 2004) in accordance with an ADEC approved protocol. These CALMET data were used in the analysis.

EPA has recently released an updated approved version of CALPUFF and the associatedsuite of processors (version 5.8). This version and the associated pre- and postprocessors were used in the BART exempt ion visibility assess ment. Th e CALPUFF modeling system consists of three main processors, CALMET, CALPUFF, and CALPOST. CALMET is the meteorological model t hat generates hourly three-dimensional meteorological fields of variables such as wind and temperature. CALPUFF simulates the transport, dispersion, and transformation of pollutants emitted from an emission unit and calculates hourly concentration values for visibility impairing compounds at each receptor located in the modeling domain. CALPOST calculates time-averaged concentration values from the CALPUFF predictions and performs visibility calculations.

Visibility impacts are determined on a daily basis. Therefore, modeled BART emission rates and exhaust parameters reflect the actual maximum daily source operating scenarios. The Kenai LNG Plant BART-eligible turbine emissions were modeled based on the conservative assumption that the turbines operated up to their compressor limited rate with inlet air pre-heating. Because emissions from the BART-eligible turbines cause approximately 96 percent of the modeled visibility impacts, the other Kenai LNG Plant BART-eligible emission units were modeled using the average daily emissions. These average daily emissions are the best reasonably available emission rates.

Other inputs included appropriate background concentrations of ammonia (0.5 parts per billion [ppb]) and hourly ozone data from Denali National Park with missing values filled using 40 ppb.Page 4 

### Once CALPUFF was run and values have been determined at each receptor in the Class I areas, the post-processor CALPOST was used to estimate the maximum daily change in visibility associated with the Kenai LNG Plant modeled emission units as compared to natural background conditions at both Tuxedni and Denali. Changes in visibility are provided by the model in delta-deciview units. The 98 th 

### percentile maximum impact was compared with the exemption threshold of 0.5 delta-deciviews.

CALPUFF Modeling Inputs and Results

The CALPUFF model emission unit parameters are shown in Table 1. These parameters were developed from the inputs shown in Table 2 (turbine inlet temperature and compressor limited characteristics) and Table 3 (emission rate calculations). The modeled parameters previously used in the ADEC-sponsored WRAP analysis are provided in Table

4.

The 12 monthly CALMET files for each year were sequentially read in a single year long run by setting NMET = 12. Hourly ozone data for Denali was obtained from the EPA CASTNET website for each year. Any missing values were filled with 40 ppb and formatted into the updated ozone.dat format. Default settings were used.

Two separate modeling runs were done, one for each Class I area. Because the settings of the modeling domain exceeded the default values in the EPA version of CALPUFF, the executables were recompiled to conform to the Geomatrix grid settings (mx = 270, my = 325). The computational grid for the Denali runs maintained the larger domain (270 by 325), whereas the runs for Tuxedni used a smaller computational grid (200 by 200).

CALPUFF was run for each year of the three year period and concentration, deposition, and visibility files were saved. The values in these files were subsequently used as input to CALPOST to determine visibility impacts.

The impact of the Kenai LNG Plant modeled emission units was calculated from the daily visibility values for each receptor by determining the change in deciviews compared against natural visibility conditions. Relative humidity can play an important role in atmospheric visibility as sulfates and nitrates accrete water and scatter more light at higher humidities. The relative humidity factor values listed in Guidance for Estimating Natural Visibility Conditions Under the Regional Haze Rule , EPA-454/B03-005 (September 2003) were applied and those values used are shown in Table 5. To determine whether a source may reasonably be anticipated to cause or contribute to visibility impairment at a Class I area, the impacts predicted by CALPUFF are compared against the pertinent natural visibility background and the selected threshold.Page 5 

### The locations of the modeled Kenai LNG Plant emission units relative to the Class I area receptors is shown in Figure 1. Also depicted is the extent of the CALPUFF modeling domain and the terrain used in the analysis. As seen in Figure 1, the Tuxedni Class I area is much nearer the Kenai plant site, but much more confined than the farther away but much larger Denali receptor grid. Receptor heights and locations were obtained from FLM

files.

CALPOST was run using Method 6 (MVISBK=6) for calculating extinction. The monthly f (RH) adjustment factors listed in Table 5 were applied directly to the background and modeled sulfate and nitrate concentrations, as recommended in the BART guidelines.

The EPA BART guidance recommends that the threshold value for defining whether a source “contributes” to visibility impairment is 0.5 dv change from natural conditions. Alaska has opted to use the 0.5 dv threshold.

Results of the modeling are shown in Table 6 in deciviews for each year for each Class I area. As shown in the table, none of the 98 th 

### percentile deciview values exceed the threshold at the many Denali receptors that were modeled. Therefore, the Kenai LNG Plant BART-eligible sources are exempt from BART regulations for the Denali Class I

area.

The results at the more proximate Tuxedni receptors suggest the potential to affect visibility exists because the 98 th 

### percentile values exceed the contribution threshold value of 0.5 deciviews. CPANGC believes these results to be conservative, given the modeling approach and the fact that the highest impacts occur during winter conditions which tend to naturally limit visibility.

Modeling Files

The CALPUFF and CALPOST input and list files are provided on CD for each Class I area. The re-compiled executables are also provided. Geomatrix has already supplied ADEC with the CALMET files used in the analysis.Page 6Table 1. Kenai LNG Plant - BART-Eligible Modeled Source ParametersLocation (LCC)Emission Rates (g/s)ModelIDEmissionUnitX (km)Y (km)StackHeight(m)BaseElevation(m msl)StackDiameter(m)ExitVelocity(m/s)Exit Temp(K)DownwashSO2SO4NOXHNO3NO3PM2.5AK37GE Frame 5Turbine#151-20.886 186.612 21.34 36.6 2.15 42.5657 0 0 0 6.53 0 0 0.12AK38GE Frame 5Turbine#152-20.887 186.612 21.34 36.6 2.15 42.5 657 0 0 0 6.53 0 0 0.12AK39GE Frame 5Turbine#251-20.883 186.612 21.34 36.6 2.15 51.4 714 0 0 0 8.87 0 0 0.15AK40GE Frame 5Turbine#252-20.884 186.612 21.34 36.6 2.15 51.4 714 0 0 0 8.87 0 0 0.16AK41GE Frame 5Turbine#351-20.886 186.612 21.34 36.6 2.15 41.9 680 0 0 0 6.4 0 0 0.13AK42GE Frame 5Turbine#353-20.887 186.612 21.34 36.6 2.15 41.9 680 0 0 0 6.4 0 0 0.13AK44Erie City 9MBoiler #501-20.878 186.612 18.98 36.6 0.97 9.71 460.9 0 0 0 0.32 0 0 0.02AK45Erie City 9MBoiler #502-20.878 186.612 18.98 36.6 0.97 9.71 460.9 0 0 0 0.3 0 0 0.02AK46Erie City 9MBoiler #511-20.877 186.612 18.98 36.6 0.97 9.51 460.9 0 0 0 0.33 0 0 0.02AK47Cat D-379EmergencyGenerator-20.879 186.612 4.27 36.6 0.2 32.9 749.8 0 0.11 0 0.49 0 0 0.03AK48GroundFlare(includingpilot)-20.9 186.644 0.91 36.6 13.7 0.001 1273 0 0 0 0.32 0 0 0.01Page 7 

### Table 2. Kenai LNG Plant – BART-Eligible Turbine Emission Parameters – Compressor Limited – Pre-heat Inlet

Amb Temp Intake Temp Power 1 HC 2 Exh Flow Exh Temp Velocity NO X

( ° F) ( ° F) (bhp) (MMBtu/hr) (lb/hr) ( ° K) (m/sec) (g/sec)

GE Frame 5 Turbines #151 and #152 – Model ID AK 37 and AK38 -35.5 40 13,166 151.5 631, 954 677 42.46861 6.5305 -26.5 40 13,166 151.5 631, 954 677 42.46861 6.5305 -17.5 40 13,166 151.5 631, 954 677 42.46861 6.5305 -8.5 40 13,166 151.5 631, 954 677 42.46861 6.5305 0.5 40 13,166 151.5 631,9 54 677 42.46861 6.5305 9.5 40 13,166 151.5 631,9 54 677 42.46861 6.5305 18.5 40 13,166 151.5 631,9 54 677 42.46861 6.5305 27.5 40 13,166 151.5 631,9 54 677 42.46861 6.5305 36.5 40 13,166 151.5 631,9 54 677 42.46861 6.5305 45.5 45.5 13,166 151.7 628, 000 684 42.60017 6.5412 54.5 54.5 13,166 152.2 621, 673 694 42.81419 6.5586 63.5 63.5 13,166 152.6 615, 516 705 43.02667 6.5759 72.5 72.5 13,166 153.0 609, 522 715 43.23764 6.5931 81.5 81.5 13,166 153.3 603, 684 725 43.44715 6.6101 GE Frame 5 Turbines #251 and #252 – Model ID AK 39 and AK40 -35.5 40 18,545 205.7 714, 087 725 51.36614 8.8682 -26.5 40 18,545 204.8 714, 087 725 51.36614 8.8291 -17.5 40 18,545 204.8 714, 087 725 51.36614 8.8291 -8.5 40 18,545 204.8 714, 087 725 51.36614 8.8291 0.5 40 18,545 204.8 714,0 87 725 51.36614 8.8291 9.5 40 18,545 204.8 714,0 87 725 51.36614 8.8291 18.5 40 18,545 204.8 714,0 87 725 51.36614 8.8291 27.5 40 18,545 204.8 714,0 87 725 51.36614 8.8291 36.5 40 18,545 204.8 714,0 87 725 51.36614 8.8291 45.5 45.5 18,545 205.1 708, 993 732 51.49408 8.8388 54.5 54.5 18,545 205.4 700, 836 744 51.70202 8.8545 63.5 63.5 18,545 205.8 692, 894 755 51.90824 8.8701 72.5 72.5 18,545 206.1 685, 156 767 52.11277 8.8856 81.5 81.5 18,545 206.5 677, 616 778 52.31566 8.9009 GE Frame 5 Turbines #351 and #352 – Model ID AK 41 and AK42 -35.5 40 13,436 148.5 629, 385 671 41.89056 6.4008 -26.5 40 13,436 148.5 629, 385 671 41.89056 6.4008 -17.5 40 13,436 148.5 629, 385 671 41.89056 6.4008 -8.5 40 13,436 148.5 629, 385 671 41.89056 6.4008 0.5 40 13,436 148.5 629,3 85 671 41.89056 6.4008 9.5 40 13,436 148.5 629,3 85 671 41.89056 6.4008 18.5 40 13,436 148.5 629,3 85 671 41.89056 6.4008 27.5 40 13,436 148.5 629,3 85 671 41.89056 6.4008 36.5 40 13,436 148.5 629,3 85 671 41.89056 6.4008 45.5 45.5 13,436 148.8 625, 499 677 42.03629 6.4125 54.5 54.5 13,436 149.2 619, 280 688 42.27336 6.4317 63.5 63.5 13,436 149.6 613, 228 699 42.50873 6.4507 72.5 72.5 13,436 150.1 607, 337 709 42.74243 6.4696 81.5 81.5 13,436 150.5 601, 600 720 42.97448 6.4883Page 8Table 3. Kenai LNG Plant - Actual Emissions from BART-Eligible Emission Units Other than Combustion TurbinesEmission UnitPollutantFuelEmission FactorMaximum CapacityActualOperationActual EmissionModelIDNameton/yrReferenceAK44Erie City 9MBoiler #5016.2 NOXNat. gas 140 lb/MMscfAP-42 Table1.4-1 (7/98)47 MMBtu/hr 4,836 hr/year 61.60 lb/day 0.323 g/secAK45Erie City 9MBoiler #5027.4 NOXNat. gas 140 lb/MMscfAP-42 Table1.4-1 (7/98)47 MMBtu/hr 6,156 hr/year 57.62 lb/day 0.302 g/secAK46Erie City 9MBoiler #5117.9 NOXNat. gas 140 lb/MMscfAP-42 Table1.4-1 (7/98)46 MMBtu/hr 6,048 hr/year 62.93 lb/day 0.330 g/secAK47Cat D-379EmergencyGenerator0.07 NOXDiesel 4.41 lb/MMBtuAP-42 Table3.3-1 (10/96)350 kW 36 hr/year 92.55 lb/day 0.485 g/secAK48Ground Flare(includingpilot)1.12 NOXNat. gas 0.068 lb/MMBtuAP-42 Table13.5-1 (1/95)148 MMscf/day 881 hr/year 61.13 lb/day 0.320 g/secNotes: 1. Natural gas has a sulfur content of 0.0 ppmv and a heat content of 1,000 Btu/scf.2. Distillate has a sulfur content of 0.1 wt. pct. and a density of 7.0 lb/gal.Page 9Table 4. Kenai LNG Plant – ADEC-Sponsored WRAP Modeled Source ParametersLocation (LCC)Emission Rates (g/s)ModelIDEmissionUnitX (km)Y (km)StackHeight(m)BaseElevation(m msl)StackDiameter(m)ExitVelocity(m/s)Exit Temp(K)DownwashSO2SO4NOXHNO3NO3PM2.5AK37CPAI KenaiLNG (90)-20.8859 186.6209 21.3360 -999.0000 2.1336 32.6136 755.3722 0 0.0000 0.00 6.2738 0.00 0.00 0.6300AK38CPAI KenaiLNG (90)-20.8859 186.6209 21.3360 -999.0000 2.1336 32.6136 755.3722 0 0.0000 0.00 6.2738 0.00 0.00 0.6300AK39CPAI KenaiLNG (90)-20.8859 186.6209 21.3360 -999.0000 2.1336 49.9872 777.0389 0 0.0000 0.00 9.4306 0.00 0.00 0.6300AK40CPAI KenaiLNG (90)-20.8859 186.6209 21.3360 -999.0000 2.1336 49.0728 777.0389 0 0.0000 0.00 9.2211 0.00 0.00 0.6300AK41CPAI KenaiLNG (90)-20.8859 186.6209 21.3360 -999.0000 2.1336 32.6136 755.3722 0 0.0000 0.00 6.3058 0.00 0.00 0.6300AK42CPAI KenaiLNG (90)-20.8859 186.6209 21.3360 -999.0000 2.1336 32.6136 755.3722 0 0.0000 0.00 6.3058 0.00 0.00 0.6300AK44CPAI KenaiLNG (90)-20.8859 186.6209 18.8976 -999.0000 0.9144 9.7536 460.9278 0 0.0000 0.00 0.5807 0.00 0.00 0.0399AK45CPAI KenaiLNG (90)-20.8859 186.6209 18.8976 -999.0000 0.9144 9.7536 460.9278 0 0.0000 0.00 0.5807 0.00 0.00 0.0399AK46CPAI KenaiLNG (90)-20.8859 186.6209 18.8976 -999.0000 0.9144 9.4488 460.9278 0 0.0000 0.00 0.0940 0.00 0.00 0.0431AK47CPAI KenaiLNG (90)-20.8859 186.6209 4.2672 -999.0000 0.3048 32.9184 749.8167 0 0.0767 0.00 1.8323 0.00 0.00 0.1302AK48CPAI KenaiLNG (90)-20.8859 186.6209 62.1792 -999.0000 13.7160 0.0010 1273.1500 0 0.0000 0.00 53.8913 0.00 0.00 0.2179Page 10Table 5. Kenai LNG Plant – Monthly RHFAC Values for Each Class I AreaJanFebMarAprMayJunJulAugSepOctNovDecTuxedni3.6 3.4 2.9 2.8 2.8 2.93.6 3.9 3.8 3.4 3.5 3.7Denali2.5 2.3 2.1 1.9 1.8 2.1 2.5 2.9 2.8 3 2.9 3Page 11 

### Table 6. Kenai LNG Plant – 98 th 

### Percentile Delta Deciview Values for Each Class I Area

2002 2003 2004 Threshold

Denali

0.122 0.099 0.128 0.5

Tuxedni

0.567 0.883 0.687 0.5Page 12 

### -200.00 -100.00 0.00 100.00 200.00 300.00 0.00 100.00 200.00 300.00 400.00 500.00 600.00



## Denali Receptors

Tuxedni Receptors

Figure 1. Kenai LNG Plant – Calpuff Modeling Domain and Locations of Emission Units (red star) and Class I Area Receptors (Tuxedni and Denali)Page 13 

### References

EPA, 1995. “Interagency Workgroup on Air Quality Modeling (IWAQM): Assessment of Phase 1 Recommendations Regarding the Use of MESOPUFF II”, EPA- 54/R-95-006. Office of Air Quality Planning and Standards, U.S Environmental Protection Agency, Research Triangle Park, NC 27711.

EPA. 1999. Regional Haze Regulations; Final Rule. Federal Register, 64, 357

13-35774.

EPA, 2003. Guidance for Estimating Natural Visibility Conditions under the Regional Haze Rule. EPA-454/B-03-005. U.S. Environmental Protection Agency, Research Triangle Park, NC.

EPA, 2005. Regional Haze Regulations and Guidelines for Best Available Retrofit Technology (BART) Determinations. Federal Register, 70 (128), Wednesday, July 6, 2005.

FLAG 2000. “Federal Land Managers’ Air Quality Related Values Workgroup (FLAG)”: Phase I Report. USDI – National Park Service, Air Resources Division, Denver, CO.

Irwin, J.S., 1998b. “Interagency Workgroup on Air Quality Modeling (IWAQM): Phase 2 Summary Report and Recommendations for Modeling Long Range Transport Impacts”. EPA-454/R-98-019, Office of Air Quality Planning and Standards, Research Triangle Park, NC, 151 pp. (NTIS Accession Number PB 99-121089).

IWAQM. 1998. Interagency Workgroup on Air Quality Modeling (IWAQM) Phase 2 Summary Report and Recommendations for Modeling Long-Range Transport and Impacts on Regional Visibility. EPA-454/R-98-019. U.S. Environmental Protection Agency, Office of Air Quality Planning and Standards, Research Triangle Part, NC.

Geomatrix, May 2007. Alaska MM5 Modeling Protocol. Prepared for Members of

the Alaska BART Coalition.

Scire, J.S., D.G. Strimaitis, and R.J. Yamartino, 2000a: A User’s Guide for the CALPUFF Dispersion Model (Version 5). Earth Tech, Inc., Concord, MA.Page 14 

### Scire, J.S., F.R. Robe, M.E. Fernau, and R.J. Yamartino, 2000b: A User’s Guide for the CALMET Meteorological Model (Version 5). Earth Tech, Inc., Concord,

M.A

NPS, 1993. “Interagency Workgroup on Air Quality Modeling (IWAQM) Phase 1 Report: Interim Recommendation For Modeling Long Range Transport And Impacts On Regional Visibility”, EPA-454/R-93-015, U.S. Environmental Protection Agency, Technical Support Division, Research Triangle Park, NC.