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## United States Department ofthe Interior NATIONAL PARK SERVICE AirResources Division P.O. Box 25287 Denver, CO 80225 

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October21, 2009

N3615 (2350)

DavidA. Finley, Administrator DivisionofAir Quality DepartmentofEnvironmental Quality 122 W. 25th Street Cheyenne, Wyoming 82002

DearMr. Finley:

On August 26, 2009, we received Wyoming's draft regional haze implementation plan for review. We appreciate the opportunity to work closely with the State through the initial evaluation, development, and, now, subsequent review ofthis plan. Cooperative efforts such as these ensure that, together, we will continue to make progress toward the Clean Air Act's goal ofnatural visibility conditions at all ofour most pristine National Parks andwilderness areas for future generations.

This letter acknowledges that the U.S. Department ofthe Interior, U.S. Fish and Wildlife Service (FWS), and National Park Service (NPS) have received and conducted a substantive review ofyour revised proposed Regional Haze Rule implementation plan in fulfillment ofyour requirements under the federal regulations 40 CFR 51.308(i)(2) and 51.309(g). Please note, however, that only the U.S. Environmental Protection Agency (EPA) can make a final determination regarding the document's completeness and, therefore, ability to receive federal approval from EPA.

As outlined in a letter to each State dated August 1, 2006, our review focused on eight basic content areas. The content areas reflect priorities for the Federal Land Manager agencies, and we have enclosed comments associated with these priorities. Overall the draftimplementationplanwas well organizedand addressed all thekey elements outlined inour letter. We recognize Wyoming is committingto significant point SOllce emissions reductions. We have two primary concerns with the draft plan: 1) the reasonable progress analyses did not consider what S02 controls beyond those included in the Section 309 State Implementation Plan might be reasonable to address visibility impairmentat Class Iareas outside the Colorado Plateau, and 2) the impacts ofincreases in NOx emissions due to the oil and gas development activities. We previously commented in a letter to you dated August 4, 2009, that we consider selective catalytic2

reduction (SCR) technology to be best available retrofit technology (BART) for several Wyoming facilities that are subjectto BART underthe regional haze rule.

We look forward to your response, as per section 40 CFR 51.308(i)(3). For further information regarding our comments, please contact Pat Brewer of the NPS Air Resources Division at 303-969-2153, or Tim Allen ofthe FWS Branch ofAir Quality at 303-914-3802. Again, we appreciate the opportunity to work closely with the State of Wyoming and compliment you on your hard work and dedication to significant improvement in our nation's airquality values and visibility.
Sincerely,

# J;:~ Chief, AirResources Division National Park Service

Enclosure

cc: Callie Videtich USEPA Region 8 1595 Wynkoop St. Mail Code: 8P-AR Denver, CO 80202-1129 Sincerely,

# ~rktu SandraV. Silva Chief, Branch ofAir Quality U.S. Fish & Wildlife ServiceNational ParkService and U.S. Fish and Wildlife ServiceComments Wyoming DraftState Implementation Plan for Regional Haze October21, 2009

General Comments Wyoming's draft State Implementation Plan (SIP) is well organized and addresses all the key elements ofa regional haze SIP as outlined in our August 2006 letter to the states. Wyoming (WY) applies Western Regional Air Partnership (WRAP) teclmical analyses to define current and natural visibility conditions, emissions inventories, state and source-sector contributions to haze at WY Class I areas, and visibilityresponse to expected emissions controls by 2018. These WRAP products provide the basis for WY's reasonable progress goals. Beyond the emissions reductions modeled by WRAP, WY documents additional nitrogen oxides (NOx) emissions reductions from BestAvailableRetrofitTechnology (BART) and WY's long-term strategy. We
are pleased with WY's commitment to these reductions and recommend that the State highlight total expectedreductions in a summarytable and summary discussionearly inthe document.

We are concerned that WY has relied on sulfur dioxide (S02) controls under the Section 309 State Implementation Plan to also cover all WY's obligations for S02 under the Section 309(g) SIP. The 309 SIP applied to Class I areas on the Colorado Plateau. Because Class I areas in WYand neighboring states are not meeting the uniform rate of progress, WY should also consideras partofits reasonableprogress analyses ifadditional S02controls wouldbe warranted for Class Iareas notonthe Colorado Plateau.

We are also concerned by the projected increases by 2018 in NO" emissions from oil and gas activities. Because these activities are located near the WY Class I areas, these emissions increases may be offsetting the benefits ofthe significant NOx emissions reductions expected from mobile and point sources distributed across the State. Several large oil and gas development projects are being planned for southern and southwestern WY. Emissions from these projects are likely not included in the WRAP Phase II projections. We recommend that WY workclosely withthe oil andgas industryto improvethe emissionprojections andto reduce emissions gromhfrom these projects.

In our previous comments on WY's BART determinations (letter dated August 4, 2009), we recommended that additional facilities could cost effectively utilize Selective Catalytic Reductiontechnology to further reduce NO" emissions.Specific Comments
Sections 2 and 3 effectively describe the WY Class Iareas andthe visibility monitoring datathat define the 20% worstand 20% bestvisibility days atthese areas. The figures in Section 3 clearly demonstrate that organic carbon matter is the largest contributor to light extinction on the 20% worst days at the WY Class I areas and that sulfate (S04) is the second most important contributor. Nitrate (NO]), elemental carbon, and coarse mass are smaller contributors on the 20% worst days. Sulfate andnitratehave largerpercentage contributions onthe 20% bestdays. It would be helpful to include in Section 3 a brief discussion of how light extinction and decivieware calculated from IMPROVE measurements. (This discussion is actuallyprovidedon pages 191 and 192 in Section 13; itwould behelpful to move itto the introductory discussion in Section 3.)
Section 4: Emissions Inventory

WY could improve the reader's understanding of the subsequent chapters by providing additional emissions inventory data. WY reports emissions as calculated by the WRAP for the WRAP 2002d and 2018PRPb inventories. It would be helpful to add the inventory tables for WRAP 2002c and 2018 PRPa inventories for S02 and NOx, and to explain that these are the basis for the CAMx PSAT source apportionment runs that are used in Section 5 to define WY contributions to S04 and NO] at WY Class I areas. WY should also clarify that the 2002d and 2018 PRPb inventories are used in the WRAP CMAQ projections ofprogress by 2018 that are presented in Section 5. Table 4.9-1 does indicate the differences between the two inventories and pg. 47 does cite that additional information on the inventories can be found in the WY Technical Support Document. However, the inventories are so important to interpretation of results in Section 5 thatwerecommendthat WYprovide the datain Section4.

The majority ofthe NOxreductions projected for the 2018PRPb inventory (Table 4.3-1) are due to reductions inthe mobile omoadandnomoad sectors. Point sourceNOxreductions areroughly 7500 tons, while NOx emissions from oil and gas activities are projected to increase by 19,000 tons (132%). There is significant uncertainty in the oil and gas productions as WY is currently reviewing proposals for several additional oil and gas projects that would increase emissions beyondthose estimatedinthe WRAPinventory.

Section 5: SourceApportionmentand Regional HazeModeling

WY cites WRAP CAMx-PSAT analyses ofcontributions to S04 and NO] from different source regions and CMAQ projections of 2018 progress. The inventories and models are subtly different so there are subtle differences inthe results between CAMx-PSAT and CMAQ. PSAT is suggesting small increases in WY's contributions to S04 (Figures 5.2.1-1 through 5.2.1-3) and NO, (Figures 5.2.2-1 throngh 5.2.2-3) by 2018 on the 20% worst days at the WY Class I areas. Referring back to the 2018PRPa S02 inventory, there is actually an increase in S02 emissions from point sources that is revised for the WRAP 2018PRPb inventoryto a decrease in S02 point
source emissions. PSATpoints outthe importance oflocation ofNOx emissions, particularly at the Bridger Wilderness Area. Oil and gas NOx emissions increases are occurring in
2southwestern andcentral WY relatively nearthe WY Class I areas. NOxreductions from mobile andpointsources are more distributed across the state.
The Weighted Emissions Potential (WEP) analyses are appropriately presented and interpreted. Organic carbon, elementalcarbon, andparticulate matter(PM) are importantcontributors to light extinction, but nonMantbropogenic sources dominate and so WY has appropriately placed less emphasis onthese constituents inthis SIP.

It wouldbe helpful to discuss in Section 5 how relative response factors are calculated to project future visibility.
CMAQ results indicate that extinction due to sulfate and nitrate will decrease slightly by 2018, buttheWY Class I areas will notachieve theuniformrate ofprogress.
As part of our ongoing consultation, on October 6, 2009, we consulted with WY staff by teleconference. During our call, it became clear that WY is expecting NOxreductions by 2018 from BART and the long-term strategy that are not included in the WRAP PSAT source apportionment and CMAQ modeling ofprogress by 2018. It is important to point this out in Section 5 even ifthere are not modeling results to demonstrate the benefits ofthese additional reductions.
Section6: BART determination

NPS previously submitted comments that SCR would be cost effective as BART for NOx emissions from additional BART-eligibleElectric Generating Units (EGU). Itwouldbe helpful to state at the end of the section the cumulative NOx reductions expected from BART implementation inWY.

Table 6.2-1 compares actual S02 emissions to S02 milestone commitments in the Section 309 SIP. The state should clarify if actual emissions or milestone commitments are used in the WRAP 2018PRPb S02 emissions inventory. Actualemissions are currently running much lower thanthe milestonecommitments.
Section 7: ReasonableProgress Goals
Section 7.5 (pg. 123) indicates that WY Reasonable Progress Goals (RPGs) for 20% Worst Days and 20% Best Days for Wyoming Class I areas are basedprimarily on results ofWRAP CMAQ modeling for 2018. WY should clarify that RPGs listed in Table 7.5-1 are the results ofWRAP 2018b modeling without any additional controls beyond WRAP 2018b modeling. Actual reductions may be greaterthanthose modeled.

Because the WY Class I areas do not achieve the uniform rate ofprogress, WY's reasonable progress analysis needs to consider S02 controls for facilities not already addressed in WY's Section 309 SIP. The S02 reductions inthe 309 SIP do not exempt WY from considering inthis 309(g) SIP how the emissions reductions expected from the 309 SIP controls, plus additional


### 3S02 controls, could be targeted to protect Class I areas that are not on the Colorado Plateau. The State could find that additional S02 controls may not be warranted, butthat finding mustbe based on an assessment ofthe reasonable progress factors noted in the EPA regulations. In Section 7.4 WY clarifies that the S02 reductions under the 309 SIP are included in the WRAP modeling. WY should also define the tons ofS02reductions expected underthe 309 SIP. Table 4.2-1 suggests a net reduction of22,000 tons S02 from all point sources by 2018, butthat figure appears to include more sources thanthose controlling underthe 309 SIP.

Table 7.2-1 is notcitedin the text ofSection7.2.

WY uses Q/d::: 10 as an indicatorofsources that shouldbe consideredunderreasonable progress for additional NO" controls. Without more specific guidance from EPA, there is precedence that other states have used a similar approach to screen sources. Applying these criteria, two units at Dave Johnson EGU, one unit at the Mountain Cement plant, and oil and gas exploration and production are identified for reasonable progress analyses. Highly cost effective NO" controls
were identified in all cases. The reader is referred to Section 8 to learn that WY does not have regulatory authority to require controls on these sources. It would be helpful to provide this information in Section 7or at a minimum to referthe readerto the specific section (8.3.4) where the outcome ofthe reasonable progress analyses is provided.

WY asserts that uniform rate ofprogress will not be met because much ofthe contribution is from uncontrollable sources. We believe that WY should do more to adopt cost effective controls forreasonable progress for those pollutants whichWY can control.

Section 8: Long Term Strategy

WY identifies contributions to Class I areas outside WYand contributions ofneighboring states to WY Class I areas. WY consulted with neighboring states through discussions in WRAP workgroups. WY cites EPA efforts to address emissions from Canada, Mexico, and marine shipping as evidence ofprogress on contributions from sources outside WY.

WY indicates that controls under Section 309 SIP will have greater benefit at WY Class I areas than the Class I areas on the Colorado Plateau. Nonetheless, WY needs to consider what additional S02 controls not considered in the 309 SIP are feasible for the WYand neighboring Class I areas.
Oil and gas development and production are important and growing sources ofNO" emissions in WY. Therefore WY should work closely with the oil and gas industry to develop better estimates ofoil and gas NO" emissions growth. Projects currently under evaluation in southern and southwestern WY (Pinedale, Hiawatha, Moxa Arch, Continental Divide-Creston, Gun Barrel, Madden Deep, and Iron Horse) could significantly increase NO" emissions beyond those already projected inthe WRAP Phase II oil and gas inventory.



### 4While WY is developing the regulatory authority to limit emissions for oil and gas activities, we encouragethe State to askindustry to offset emissions priorto regulatory requirements. Ozone nonattainment in the Sublette County area will require WY to develop NOxemissions reduction strategies. Emissions offsetrequirements currentlyinplace are a start.
Given that WY lacks regulatory authority for additional controls for non-BART sources, it is importantthatWYrevisitcontrols options in 2013. Long-term control strategies at BART facilities are welcome. A table to support Figure 8.3.6·7 would be helpful to understand the magnitude ofexpected emissions reductions from BART implementation and underthe long-term strategy. The table provided by WY after our call was veryhelpful inunderstanding the sources ofemissions reductions.
WY's long-term strategy includes discussion ofexisting programs, including EPA discussions with Canada and Mexico over international emissions, existing WY control programs, natural events plan, measures to mitigate impacts from construction activities, and Smoke Management techniques. We encourage WY to also consider cost-effective controls for point source emissions offine particles, the anthropogenic contribution to dust (fine PM and course PM), and prescribed fire.

We ask that WY include in the discussion ofNew Source Review and Prevention ofSignificant Deterioration requirements recognition of visibility improvement goals so that progress in reducing emissions from existing sources is notoffsetby growthinnew sources.
We lookforward to continuingto workwithWYto protectvisibility and otherairquality related values inthe Class I areas andtheregion.



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