**I~NVIRONMENTAL** PROTECTION AGENCY 40 CFRPart 52 EPA-R08-0AR-2009-0557; FRLApproval and Promulgation ofState Implementation Plan Revisions; State ofNorth Dakota; Interstate Transport ofPollution for the 1997 PM2.5 and 8-hour Ozone NAAQS: "Interference with Maintenance" Requirements AGENCY: Environmental Protection Agency (EPA). ACTION: Proposed Rule. SUMMARY: The Environmental Protection Agency is proposing partial approval ofthe State Implementation Plan (SIP) revisions called "Interstate Transport ofAir Pollution" addressing the '"inkrlcrence with maintenance" requirement ofClean Air Act (CAA) section 11 O(a)(2)(D)(i) for the 1997 line particulate matter (PM25) and 8-hour ozone National Ambient Air Quality Standards (NAAQS). 

### In this action EPA proposes to approve theNorth Dakota Interstate Transport 

### SIP sections that address the requirements ofsection 11O(a)(2)(D)(i) prohibiting a state's emissions from interiCring with maintenance by any other state ofthe 1997 PM25 and 8­ hour ol.one NAAQS. This action is being taken under section 110 ofthe CAA. DATES: Comments must be received on orbefore IInsc:rt date 30**day~.?Dcr -ill!.Qlic~.iQn**  in the Federal Register]. ADDRESSES: Submit yourcomments, identified hy Docket 

## In No. EPA-R08-0AR-2009­ 0557, by one ofthe following methods:**1.J.!1Q:l!~y.\-,,-,\y~~g!JJ(iJL9ns.gov.** Follow the on-line instructions for submitting comments. E-mail: mastranl.?elo.do_Dlc:niq)(akpa.l.?oY Fax: (303) 312-6064 (please alert the individual listed in the FOR FURTHERPage 2 of'29 

### INFORMATION CONTACT ifyou arc faxing comments). Mail: Callie Videtich, Director, AirProgram, Environmental Protection Agency (EPA), Region 8, Maiicode 8P-AR, 1595 Wynkoop Street, Denver, Colorado 80202-1129. Iland Deiivery: Callie Vidctich, Director. Air Program. Environmental Protection Agency (EPA), Region 8, Mailcode 8P-i\R, 1595 Wynkoop, Denver, Colorado 80202-1129. Such deliveries are only accepted Monday through Friday, 8:00

a.m. to 4:30 p.m., excluding Federal holidays. Special arrangements should be made for deliveries ofboxed information. Instructions. Direct your comments to Docket ID No. EPA-R08-0AR-2009-0557. EPA's policy is that all comments received will be included in the public docket without change and may be made available online at http://www.regulations.u.ov, including any personal intormation provided, unless the comment includes information claimed to be Confidential Business Information (eBl) or otherinformation whose disclosure is restricted by statute. Do not submit information that you considerto be CHI or otherwise protected through**bl!.I2iLY'{'0!vv.regulations.~.wv** or e-mail. The**h1tP:l/\I;~Vi~[~~~jati()Jl.'Lgs.2-'**Web site 1S an "anonymous access" system, which means EPA will not know your identity or contact information unless you provide it in the body ofyour comment. Ifyou send an e-mail comment directly to EPi\,without going through http://www.regulations.gov, youre-mail address will be automatically captured and included as part ofthe commentthat is placed in the public docket and made available on the Internet. Ifyou submit an electronic comment, EPArecommends that you include your name and othercontac1 information in the body ofyour comment and with anyPage.") or29 disk or CD-ROM you submit. IfEPA cannot read your comment due to technical dirticulties and cannot contact you for clarification, EPA may not be able to consider yourcomment. Electronic files should avoid the use ofspecial characters, any form ofencryption, and be free of any defects or viruses. For additional instructions on submitting comments, go to Section 

### 1. (Jeneral Information ofthe 

### SUPPLEMENTARY INFORMATION section ofthis document. 

### Docker.· All documcnts in the docket arc listed in the**httl2://w.~Y.{-,-[~ggl'!1i9.mum'{** index. Although listed in the index, some information is not publicly available, e.g.,

## em or other inl<mnation whose disclosure is restricted by statute. Certain other material, such as copyrighted material, will be publicly available only in hard copy. Publicly-available docket materials arc available eitherelectronically in httl2://www.regulations.gov orin hard copy atthe Air Program, Environmental Protection Agency (EPA), Region 8, Mailcode 8P-AR, 1595 Wynkoop, Denver, Colorado 80202-1129. EPA requests that irat all possible, you contactthe individual listed in the 

### FOR FURTHER INFORMATION CONTACT section to view the hard copy ofthe docket. You may view the hard copy ofthe docket Monday through Friday, 8:00 a.m. to 4:00 p.m., excluding Federal holidays. 

### FOR FURTHERINFORMATION CONTACT: Domenico Mastrangelo, Air Program, U.S. l:nvironmental Protection Agency, Region 8, Mailcode 8P-AR, 1595 Wynkoop, Denver, Colorado 80202-1129. (303) 312-6436, mastgngelo.domcntco(LI)el2a.gov. 

### SUPPLEMENTARY INFORMATION: Definitions For the purpose ofthis document, we are giving meaning to certain words or initials as follows: (i) The words or initials A<,;t orCbA mean or referto the Clean Air Act. unless the contextPagc4of29 indicates othcrwisc. (ii) The words EPA, wc, us or Qur mean or rcfcr to the United States r:nvironmental Protection Agency. (iii) The initials

## SIE mean orreferto State Implementation Plan. (iv) The words NQ.r:!hl)l;lkota and State mean the State ofNorth Dakota. Tablc ofContcnts I. Gcncral Information What Should IConsider as I Prepare My Comments for EPA? II. Background III. WhatAction Is EPA Proposing? IV. What Is the State Process to Submit This Material to EPA'! V. F..PA's Review and 

### Technical Information A. EPA's Evaluation ofInterference with Maintenance 

### B. North DakotaTransport SIP VI. Proposed Action VII. StatutoI)' and Executive Order Reviews I. General Information What should Iconsider as Iprepare my comments for EPA? 

### ]. Suhmilling CBI Do not submit CHI to EPAthrough http://www.reQulation:;.go\i or email. Clearly mark the part or all ofthe information that you claim 10 be CHI. For 

### eBI inf()rmation in a disk or CD ROM that youmail to EPA, mark the outside ofthe disk orCD ROM as CHI and then identify electronically within the disk or CD ROM the specificPage 5 of29 information that is claimed as CBI. In addition to one complete version ofthe comment that includes information claimed as CHI, a copy ol'the comment that does not contain the in1'ormation claimed as CHI must be submitted**f~)r** inclusion in the public docket. fnrormation so marked will not be disclosed except in accordance with procedures set rorth in 40 CFR part 2. 2. Tipsj(Jr PreparinR Your Commenfs. When submitting comments, rememberto:

a. Identify the rulemaking by docket number and otheridentifying information (subject heading, Federal Registerdate and page number). b. Follow directions

- The agency may ask you to respond to specific questions or organize comments by referencing a Code ofFederal Regulations (CFR) part or section number.

c. Explain why you agree ordisagree; suggest alternatives and substitute language for your requested changes. d. Describe any assumptions and provide any technical information and/ordatathat you used.

e. Ifyou estimate potential costs or burdens, explain howyou arrived at your estimate in sutlicient detail to allow for it to be reproduced. 

## r. Provide specific examples to illustrate your concerns, and suggest alternatives. g. Expluin your views as clearly as possible, avoidingthe usc ofprofanity or personal threats. h. Make sure to submityour comments by the comment period deadline identified. II. Background On July 18, 1997, EPApromulgated new NAAQS for ozone and for PM2 ). This actionPage 6 oC29 is being taken in response to the promulgation ofthe 1997 PM2 :i and 8-hour ozone Ni\i\QS. This action docs not address the requirements for the 2006 24-hour PM2 :i or 2008 8-hour ozone Ni\i\QS; those standards will be addressed in lateractions. Section 11 O(a)( 1) ofthe Ci\i\ requires states to submit SIPsto address a new orrevised Ni\i\QS within 3 years after promulgation ofsuch standards, or within such shorterperiod as**l~Pi\** may prescribe. Section 110(a)(2) lists the clements that such new SIPs must address, as applicable, including section 110(a)(2)(D)(i), which pertains to interstate transport ofcertain emissions. On August 15,2006, EPA issued its "Guidance for State Implementation Plan (SIP) Submissions to Meet Current Outstanding Obligations Under Section 11 O(a)(2)(D)(i) for the 8­ Ilour Ozone and PM2:i :\ational Ambient Air Quality Standards" (2006 Guidance). EPA developed the 2006 Guidance to make recommendations to states for making submissions to meet the requirements ofsection 110(a)(2)(D)(i) for the 1997 8-hour ozone standards and the 1997 PM2 :i standards. As identified in the 2006 Guidance, the "good neighbor" provisions in section IIO(a)(2)(D)(i) require each state to submit a SIP that prohibits emissions that adversely affect another state in the ways contemplated in the statute. Section 110(a)(2)(D)(i) contains Cour distinct requirements related to the impacts ofinterstate transp0l1. The S[P must prevent sources in the state from emitting pollutants in amounts which will: (1) contribute significantly to nonattainment ofthe Ni\AQS in other states; (2) interfere with maintenance ofthe Ni\AQS in other states; (3) interfere with provisions to prevent significantdeterioration ofair quality in other states; or (4) interCere with efforts to protect visibility in other states. On i\pril 6, 2009 LPi\ received a SIP revision from the State oP\orth Dakota intended toPage 7 of29 address the requirements ofsection IIO(a)(2)(D)(i)**j~)r** both the 1997 8-hourozonc standards and the 1997 PM25 standards. In this rulemaking, EPA is addressing only the requirements that pertain to preventing sources in North Dakota from emitting pollutants that will interfere with maintenance ofthe ]997 8-hour OIone NAA()S and the 1997 PM} 5 NAAQS by other states. In its submission, the State of0iorth Dakota indicated that its current SIP is adequate to prevent such interference. With this submission, the state intended to meet the recommendations ofthe 2006 Guidance for SIP submissions to meet thc second element ofscction II0(a)(2)(D)(i) for the 1997 PM25 and 8-hour070ne standards. 

### Ill. WhatAction Is EPA Proposing? EPA is proposing partial approval orthe North Dakota Interstate Transport ofAir Pollution SIP for the 1997 PM25 and 8-hour ozone NAAQS. The addition to thc North Dakota SIP ofsection 7.8, "InterstateTransport ofAir Pollution," was adopted by the State ofNorth Dakotaon April I, 2009 and submitted to EPA on April 6, 2009. EPA is proposing to approve the language and demonstrations ofthe North Dakota Interstate Transport SIP that address clement (2) ofsection II0(a)(2)(D)(i), i.e
.. the prohibition ofinterference with maintenance of the 1997 8-hourozone NAAQS and the 1997 PM25 NAAQS by any other statc. 

### IY. What Is the State Process to SubmitThis Material to EPA? Section IIO(k) ofthe CAA addresses EPA's rulemaking action on SIP submissions by states. The CAA requires states to observe certain procedural requirements in developing SIP revisions for submittal to EPA. Section 110(a)(2) of the CAA requires that each SIP revision be adopted after reasonable notice and public hearing. This must occur prior to the revision being submitted by a state to EPA.Page 8 01'29 The North Dakota Department ofHealth (NDDH) held a public hearing on October 7, 2008 for the addition to the North Dakota SIP ofthe Interstate Transport non-regulatory provisions. The NDDI-I adopted the provisions on April 1, 2009 and suhmitted them to EPA on April 6, 2009.**L~PA** has reviewed the submittal by the NDDH and has determined that the State met the requirements for reasonable notice and public hearing under section 110(a)(2) ofthe CAl\. 

## v. EPA's Review and Technical Information A. EPA's Evaluation ofInterference with Maintenance The second dement ofsection II0(a)(2)(D)(i) requires that a state's SIP must prohibit any source or other type ofemissions activity in the state from emitting pollutants that would "interCcre with maintenance" ofthe applicable NAAQS by any other state. This term is not defined in the statute. Therefore, EPA has interpreted this term in past regulatory actions, such

as the 1998 NOx SIP Call, in which EPA took action to eliminate emissions ofNOx that significantly contributed to nonattainment, orinterfered with maintenance of, the then applicable

ozone NAAQS through interstate transport ofNOx and the resulting ozone. I The NOx SIP Call

was the mechanism through which FPA evaluated whether or not the \lOx emissions from

sources in certain states had such prohibited interstate impacts, and ifthey had such impacts, required the states to adopt substantive SIP revisions to eliminate the NOx emissions, whether through participation in a regional cap and trade program or by other means. Alter promulgation ofthe 1997 8-hourozone NAAQS and the 1997 PM2 -; NAAQS, EPA

--_._-- --_.....

### _--­**S~~,** 63 FR 5n5(,**(Octob~r** 27. 1998). EPA's general approach to section [ [0(a)(2)(D) was upheld in Michigan v.**l~r)A,** 213 F.3d 663 (DC Cir. 2000), cel1 denied, 532 L.S. 904 (2001). However, EPA's appl"Oach to interference I

### Pagc90f29 again recognized that regional transport was a serious concem throughout the eastem U.S. and therefore developed the 2005 Clean Air Interstate Rule (CAIR) to address emissions ofS02 and NOx that exacerbate ambient ozone and PMZ5 

### levels in many downwind areas through interstate transport. 2 

### Within CAIR, EPA likewise interpreted the term "interfere with maintenance" as part ofthe evaluation ofwhether or not the emissions ofsources in certain states had such impacts on
areas that EPA determined would eitherbe in violation ofthe NAAQS, or would be injeopardy ofviolating the NAAQS, in a modeled future year unless action were taken by upwind states to reduce SOz and NOx emissions. Through CAIR, EPA again required states that had such interstate impacts to adopt substantive SIP revisions to eliminatethe SOz and NOx emissions, whether through participation in a regional cap and trade program orby othermeans. EPA's 2006 Guidance addressed section 110(a)(2)(D)(i) requirements for the 1997 8­ hour ozone NAAQS and 1997 PMZ5 

### NAAQS. Forthose states subject to CAlK EPA indicated that compliance with CArR would meet the two requirements ofsection 110(a)(2)(D)(i)(I) for these NAAQS. For states not within the CArR region, EPA recommended that states evaluate whetheror not emissions from their sources would "interfere with maintenance" by other states, following the conceptual approach adopted by EPA in CAIR. Afterrecommending various types ofinformation that could be relevant for the technical analysis to support the SIP submission, such as the amount ofemissions and meteorological conditions in the state, EPA further indicated that it would he appropriate for the state to assess impacts ofits emissions on other states using considerations comparableto those used by EPA "in evaluating signif'icant



### --_.. ....

## _- ------- ..**~.-._-_** - -"



# _ . with maintenance in the ,\;Ox SIP Call was not explicitly reviewed by the court. Sec. North Carolina v. U)!\, 531 F.3d 896,90709 (D.C. (,ir. 200R).Page 1001'29 contribution to nonattainment in the CAlK'" EPA did not make specific recommendations for how states should assess "'interference with maintenance" separately, and discussed the first two clements ofsection 110(a)(2)(D)(i) together without explicitly differentiating between them. In 2008, however, the U.S. Court ofAppeals for the D.C. Circuit found that CAIR and the related CAIR federal implementation plans were unlawfLJ!.4 Among other issues. the court held that EPA had not correctly addressed the second clement ofsection 110(a)(2)(D)(i)(l) in CAIR. The court noted that "EPA gave no independent significance to the 'interfere with maintenance' prong ofsection 110(a)(2)(D)(i)(I) to separately identify upwind sources interfering with downwind maintenance."s EPA's approach, the court reasoned, would leave

areas that arc "'barely meeting attainment" with "no recourse" to address upwind emissions snurces() The court therefore eoncludcd that a plain language reading ofthe statute requires EPA to give independent meaning to the interfere with maintenance requirement ofsection I 10(a)(2)(D) and that the approach used by EPA in CAIRfailed to do so. In addition to afTeeting CAIR directly, the court's decision in the North Carolina case indirectly affects EPA's recommendations to states in the 2006 Guidance with respectto the interference with maintenance dement ofsection 11 O(a)(2)(D)(i) because the agency's guidance suggested that states use an approach comparable to that used by EPA in CAIR. States such as 0:orth Dakotadeveloped and adopted their Interstate Transport SIP not long afterthe Court's July 2008 decision, but well before EPA, in the Transport Rule Proposal (sec below), was able to

-----_._--_._---­ 2 Sec, 70 FR 25162 (May 12, 2005). ' 2006 Guidance at 5.

Sec. North Carolina v. j·;PA. 531 F.3d 896 (D.C. Cir. 2008). 'i Id.**(~19()9.** (, Id. IPage 11 01'29 propose a new approach for the interference with maintenance clement. Without recommendations from EPA, North Dakota's SIP may not have sufliciently ditTerentiated between the significant contribution to nonattainment and interference with maintenance clements ofthe statute, and relied in a general way on the difference between monitored concentrations and the 1997 8-hour ozone NAAQS to evaluate the impacts ofState emissions on maintenance ofthe NAAQS in neighboring states. EPA believes that it is necessary to evaluate these state submissions for section IIO(a)(2)(D)(i)(l) in such a way as to assure that the interfere with maintenance clement ofthe statute is givcn independent meaning and is appropriately evaluated using the types ofinformation that I:PA recommended in the 2006 Guidance. To accomplish this, EPA believes it is necessary to use an updated approach to this issue and to supplement the technical analysis provided by the state in order to evaluate the submissions with respect to the interfere with maintenance element ofsection 11 O(a)(2)(D)(i). EPA has recently proposed a newrule to address interstate transport pursuantto section I IO(a)(2)(D)(i), the "Federal Implementation Plans to Reduce Interstate Transport ofFine Particulate Matter and Ozone" (Transport Rule Proposal), in order to address thejudicial remand ofCAIR. 7 As part ofthe Transport Rule Proposal, EPA specifically reexamined the section II0(a)(2)(D) requirement that emissions from sources in a state must not "interfere with maintenance" ofthe 1997 8-hour ozone NAAQS and 1997 PM2 'i NAAQS by other states. In the proposal, EPA developed an approach to identify areas that it predicts to be close to the level of the 1997 8-hourozone ;,\AAQS and 1997 PM2 'i NAAQS in the future. and therefore at risk to 

## -_..... 

### ---_..._ ...- ...-.-.--­ 7 See "Federal Implementation Plans to Reduce Interstate Transport ofFine [)articulate \t1atter and Ozone," 75 FR 45210 (August 2. 20)0).**P~lge** 12 of29 become orcontinue to be nonattainment II)r these NAAQS unless emissions from sources in other states arc appropriately controlled. This approach starts by identifying those specific geographic areas for which further evaluation is appropriate, and differentiates between areas where the concern is with interference with maintenance, ratherthan with significant contribution to nonattainment. As described in more detail below, LPNs analysis evaluates data from existing monitors

overthree overlapping three-year periods (i.e., 2003-2005, 2004-2006, and 2005-2007), as well

as airquality modeling data, in order to determine which areas are predicted to be violating the 1997 8-hourozone and PM25 NAAQS in 2012, and which areas are predicted potentially to have difficulty with maintaining attainment as ofthatdate. In essence, ifan area's projected data (I)r 2012 indicates that it would be violating the l\JAAQS based on the average ofthese three overlappingperiods, then this monitor location is appropriate**j~)r** comparison for purposes ofthe significant contribution to nonattainment clement ofsection 110(a)(2)(D)(i). 

# If: however, an area's projected data indicate that it would be violating the NAAQS based on the highest single period, but not overthe average ofthe three periods, then this monitorlocation is appropriate fl)!" comparison for purposes ofthe intericrence with maintenance element ofthe statute. By this method, EPA has identilied those areas with monitors that arc appropriate ""maintenance-only sites" or maintenance "receptors'" iorevaluating whetherthe emissions from

sources in another state could interfere with maintenance in that particular area. f':PA then uses otheranalytical tools to examine the potential impacts ofemissions from upwind states on these maintenance receptors in downwind states.**L~P** A believes that this new approach fl)r identieyingPage 13 of29 those areas that arc predicted to have maintenance problems is appropriate to evaluate the section 11O(a)(2)(D)(i) SIP submission ora state for the interference with maintenance element.s F:PA's 2006 Cjuidance did not provide this specific recommendation to states, but in light ofthe court's decision on CAIR, I':[>A will itselfrollowthis approach in acting upon the North Dakota submission. As explained in the 2006 Guidance, EPA does not believe that section 110(a)(2)(D)(i) SIP submissions trom all states necessarily need to follow preciselythe same analytical approach

as CAIR. In the 2006 Guidance, EPA stated that: "EPA believes that the contents ofthe SIP submission required by section 110(a)(2)(D)(i) may vary depending upon the facts and circumstancesrelated to the specific NAAQS. In pmiicular, the data and analytical tools available at the time the State develops and submits a SIP for a new orrevised NAAQS necessarily arTects the contents ofthe required submission."') EPA also indicated in the 2006 Guidance that it did not anticipate that sources in states outside the geographic area covcred by CAIR werc significantly contributing to nonattainment, or interfering with maintenancc, in other states. IO As notcd in the Transport Rule Proposal, EPA continuesto belicvc that thc morc widcspread and serious transport problems in the castern United States arc analytically distinct. Forthe 1997 8-hourozone NAAQS and the 1997 PM25 NAAQS, EPA believesthat nonattainment and maintenance problems in the western United States are relatively local in



### --_

..._.

# __.­ xTo begin this analysis, I:P/\ first identifies alll1lonitors projected to be in nonallainll1ent 01', based 011 historic variability in air quality, projected to have maintenance problems in :W12. These maintenance areas arc at risk not to st,t)' in attainment because they are so close to the level 01" the 1997 ozone and PM2 , N/\/\QS that minor variations in weather or emissiolls could result in violations ofthe "I/\/\QS in 20\2. ') 2006 C,uidance at :J. III Id. at 5.Page 14 of29 nature with only limited impacts from interstate transport. I I In the Transport Rule Proposal, EPA did not calculate interstate ozone or PM25 contributions to orfrom western States. Accordingly, EPAbelieves that section 11O(a)(2)(D)(i) SIP submissions Cor states not evaluated in the Transport Rule Proposal may be evaluated using a "weightofthe evidence" approach that takes into account availahle relevant information, such as that recommended by EPA in the 2006 Guidance for states outside the area aJlected by CAIR. Such information may include, but is not limited to, the amount ofemissions in the state relevant to the NAAQS in question, the meteorological conditions in the area, the distance from the state to the nearest monitors in other states that are appropriate receptors, or such other information as may be prohative to consider whether sources in the state may interfere with maintenance ofthe 1997 8­ hour ozone and PM25 NAAQS in other states. These submissions can rely on modeling when acceptable modeling technical analyses are available, but EPA does not believe that modeling is necessarily required ifother available information is suHicient to evaluate thc presence or degree ofinterstate transport in a given situation. As a result, in the Transport Rule ProposaL EPA f()cused its modeling on a domain including eastern states. The Transport Rule Proposal's modeling domain includes all states cast ofthe Rockies, from North Dakota in the north to Texas in the south and eastward, and its analysis results include estimates ofNorth Dakota's contribution to the maintenance-only sites within the Transport Rule Proposal's modeling domain for the 1997 annual PM25 and 8-holll'

ozone NAAQS. To reach a comprehensive determination on whetheremissions from North

II Scc, Transport Rule Proposal, 75 FR 45210, /1,5277.

### Page 1501'29 Dakota interfere with maintenance ofthe NAAQS by any other states we use these estimated contributions in combination with othertypes ofinformation that allow us to assess whether emissions from North Dakota interfere with maintenance ofthe NAAQS by states outside the Eastern modeling domain. 

### B. North Dakota Transport SIP To meet the requirements ofsection 11O(a)(2)(D)(i), the State ofNorth Dakota on April 6, 2009 made a SIP submission to EPAaddressing interstate transport for the 1997 PM25 

### and the 8-hour ozone NAAQS. EPA has previously approved this submission for purposes ofthe significant contribution to nonattainment and ofthe interference with PSD clements ofsection 110(a)(2)(D)(i).12 The State's submittal focused primarily on whether emissions from North Dakota sources signilicantly contribute to nonattainmcnt ofthe 1997 8-hourozoneNAAQS and 1997 PM25 

### NAAQS in otherstates. Followingthe 2006 Guidance and consistent with

## r:.:pA's approach in CAIR, North Dakota did not evaluate whether emissions from the State sources interfere with maintenance ofthese NAAQS by other states separately from significant contribution to nonattainment in other states. Instead, the State presumedthat ifNorth Dakota

sources were not significantly contributing to violations ofthe NAAQS in other states, then no further specific evaluation was necessary for purposes ofthe interference with maintenance clement ofsection 11 O(a)(2)(D)(i). As explained above, however, CAIR was remanded to EPA, in part because the court found that EPA had failed to give independent meaning to the "interfere with maintenance" requirement, a flaw that EPA has remedied in the Transport Rule Proposal.

-- ..•....

# _._--_ _--_._­ I'SCC, 75 FR33174(Junc 1\,2(10)Page 1601'29 ]]owever. North Dakota submitted its Interstate Transport SIP without the benefit ofEPA's new interpretation. We therefore discuss in more detail the approach ofthe Transport Rule Proposal and apply it to ourassessment ofwhether North Dakota's emissions interfere with maintenance ofthe relevant NAAQS by any other states. Below, we discuss in greaterdetail relevant methods and techniques ofthe Transpoli Rule ProposaL followed by our assessment ofwhetheremissions from North Dakota interfere with maintenance ofthe 1997 PM25 and 8-hour ozone NAAQS. On July 6, 

### 2010, the EPA Administrator signed a proposed rule in response to thejudicial remand ofCAIR. The Transport Rule Proposal, published August 

### 2,20I

### 0, includes a new approach to determinewhetheremissions from a state interfere with maintenance ofthe 

### 1997 8­ hour ozone NAAQS and the 

### 1997 PM2jNAAQS by other states. In this action, EPA is using modelingresults from the Transport Rule Proposal to assess whether North Dakota emissions interfere with maintenance ofthe NAAQS by states included in the proposed rule's lllodeling domain. We usc a comparable approach to assess whether North Dakota interferes with maintenance ofthe NAAQS by western states, not modeled f{)r ozone or PM25 contributions from North Dakota. In the Transport Rule Proposal, EPA projected future concentrations ofozone and PM2 5 at monitors to identify areas that are expected to be out ofattainment with NAAQS or to have dirliculty maintaining compliance with the NAAQS in 

### 2012. These areas are referred to as nonattainment and maintenance receptors respectively. These nonattainment and maintenance receptors are hased on projections offuture air quality at existing ozone and PM25 monitoring sites in those locations. EPA then used these sites as the receptors for eXamining thePage 1701'29 contributions ofemissions from sources located in upwind states to nonattainment and maintenance problems at these monitoring locations. For ozone, EPA evaluated airquality, or ozone concentrations, relative to the 1997 8­ hour ozone NAAQS. The 1997 8-hour ozone NAAQS is set at 0.8 parts per million. The 8-hour

ozone standard is met ifthe 3-year average ofthe annual 4th highest daily maximum 8-hour

ozone concentration is less than or equal to 0.08 ppm (i.e., less than 85 ppb based on the rounding convention in 40 CFR part 50 Appendix I). This 3-yearaverage is referred to as the '"design value." For PM2 ), EPA evaluated concentrations for both the annual PM2 ) NAAQS and the 24­ hour PM2) NAAQS. The 1997 annual PM2 ) NAAQS is met when the 3-year average ofthe annual mean concentration is 15.0 micrograms per cubic meter (lJ.g/m3) or less. The 3-year average annual mean concentration is computed at each site by averaging the daily Federal RefCrence Method (FRM) samples by quarter, averaging these quarterly averages to obtain an annual average, and then averaging the three annual averages to get the design value. The 1997 :24-hour PM2 :) NAAQS is met when the 3-year average ofthe annual 98th percentiles is 65

### ~tg/m3 or less. 13 The 3-year average mean 98th percentile concentration is computed at each site by averaging the three individual annual 98th percentile values at each site. The 3-yearaverage 98th percentile concentration is referred to as the 24-houraverage design value. To project future ozone and annual PM2 5 design values, EPA relies on monitoring data from the Air Quality System (AQS) combined with photochemical air quality modeling results
.

....**_--~--_._-_._----** 11 Tht: 2006 24-hour PM}, NAAQS, which is not the subject ofthis action, is met when the 3-year avcrage ofthc 'Innual 98th percentile PM2 ) concentrations is 35 f,lg/m'or less.**Pag~180f29 Th~**  Transport Rule Proposal generates the projected future**ozon~** values**bas~d** on an**av~ragc** or three design value periods which include**th~** years 2003-2007 (i.e., design values for 2003-200S. 2004-2006, and 200S-20(7). The average ofthe three design values creates a "5-year weighted average" value. The 5-year weighted average values were then projected to the future years that**w~r~** analyzed for the Transport Rule Proposal. 14 EPA used the S-year weighted average conccntrationsto project concentrations anticipated in 2012 to determine which monitoring sites

are expected to be nonattainment in this future year. EPA also projected 2012 design values based on each ofthe three year periods (i.e., 2003-2005, 2004-2006, and 200S-2007.) The highest projection,**ref~rred** to as "maximum design value," gives an indication ofpotential variability in future projections due to differences in actual meteorology and emissions from what was modeled. EPA identified those sites that are projectedto be attainment based on the S-year weighted average design value, but that have a maximum design value (based on a single three yearperiod) that exceeds theNAAQS. as maintenance receptors. These sites are attaining the NAAQS based on the projected average design values, but EPA anticipates that there will be

more dilTiculty in maintaining attainment ofthe NAAQS atthese locations ifthere**ar~** adverse variations in meteorology or emissions. These projected maintenance sites arc the ones that EPA has used to determine ifemissions from North Dakota sources potentially interfere with maintenance ofthe 1997 8-hour ozone NAAQS and 1997 annual PMn NAAQS in other states in this action.

14 Sec, Transport Rule Proposal, at 45246.Page 1901'29 To evaluate ambient impacts from upwind states to maintenance receptors, the Transport Rule Proposal uses a two step approach for measuring each state's significant contribution. In the first step, EPi\ evaluates through airquality modeling, contributions from individual states to downwind maintenance receptors. States whose contributions to any downwind receptors which

arc above the "significant contribution" threshold, one percent ofthe relevantNAi\QS, are considered "linked" to thosc receptors for the purpose ofthe second step. Inthe second step, EPA uses maximum costthresholds, infoTIncd by airquality considerations, to detenninethe portion ofeach state's contribution that constitutes its "interfcrcnce with maintenance," or "signillcant contribution."l) EPi\ Transport Rule Proposal proposed a threshold for "interference with maintenance" at one percentofthe Ni\AQS for both PM2 ) and ozone.III Forthe 1997 annual PM2.) EPA proposed in the Transport Rule Proposal a threshold of0.15 ).tg/m3
, without any further rounding up. I? States contributing less than 0.15 

### ).tg/m3to downwind maintcnance receptors are belowthe threshold and as a result are excluded from further analysis. States contributing 0.15

### ~lg/m3 or

more arc above the threshold and are "linked" to the counties in whichthe affected receptors are located. States with "linkages" to downwind maintenance receptors are included in the analytical process that determines the controls (ifany) requircd for compliance with the "interference with maintenance" element ofscction 11O(a)(2)(D)(i) for the 1997 PM25 standards.

I'j'or tktails, see: id., at 45233 et seq., and "Air Quality Modeling Technical Support Document," (AQMTSD) (June 2{) I0). Dvai labIe at Regulations.gov as Document ID No. EPA-I IQ-OAR-2009-049 1-0047. For greater detaiI 011 <til' quality contributions sel'; "Tnll1sport Rule Air Quality Contributions," Document ID No. EPA-11Q-OAR­ 2009-{)-'191-()060 !(, Tr,lI1sport Rule Proposal, at ·15237. ;7 Note that, difkrently I"rom CAlK the Transport Rule decouples the precision orairquality thresholds from the monitoring reporting 1"Ct]uiremenLS and uses 2-digit values representing olle percellt orthe NAAQS. Id.Page 20 of29

For the 1997 8-hour ozone standard, EPA Transport Rule Proposal proposed a threshold for "interference with maintenance" at 0.8 ppb, one percent ofthe NAAQS. State contributions

or0.8 ppb and higher are considered above the threshold, while state contributions less than (J.8 ppb are below the threshold and such statcs are excluded from further analysis. Statcs contributing significantly, 0.8 ppb or more, to downwind maintenance receptors are considered to he "linked" to the counties in which they are located and are included in the follow-up process that determines the controls (ifany) required ofsuch states to satisfy the "interfere with maintenance" clement ofsection 11 O(a)(2)(D)(i) for the 1997 8-hour ozone standard. IX

In the Transport Rule Proposal, EPA projected future concentrations ofPM25 to identil'y receptors that are expected to have difficulty maintaining compliance with the NAf'QS in 2012, referred to as maintenance-only sites or maintenance receptors. Forthe 1997 annual PM25 NAAQS, the Transport Rule Proposal identified 16 maintenancereceptors in its modeling domain. The monitors at risk ror maintenance are located in seven states. includingtwo in Illinois (Cook County). four in West Virginia, six in Ohio, and one each in Kentucky, New YOlk Pennsylvania and Texas.I'J To determine the states in the Eastern domain that contribute significantly to maintenance receptors, the Transport Rule models the states' PM25 contrihution to the maintenance receptors in these states. The largest contribution from North Dakota emissions to the maintenance receptors in these states was estimated to be 0.05 )J.g/m3

, a level

---_..._------_..

# _­ IK Id. I" Table IVC-S. id
.. at 45248Pagc 

### 2101'29 two thirds below the "significant contribution"threshold of0.15 Ilg/m'. 21) This small contribution excluded North Dakota from the Transport Rule Proposal's follow-up analysis for the states that contributed significantly and were "linked" to at least one ofthe monitors at risk for maintenance ofthe NAAQS.21 To assist in the evaluation ofwhether emissions from a state's sources interfere with maintenance ofthe NAAQS in western states, EPA has developed, independent ofthe Transport Rule ProposaL a modeling analysis identifying monitors at risk for maintenance ofthe NAAQS within a modeling domain that includes the western states. The analysis presented in the memo, "Documentation ofFuture YcarOzone and Annual PM25 Design Values for Western States" (Western States Design Values), uses model results from the Transport Rule Proposal modeling Continental U.S. 

### 36 km grid, which is coarser than the 

### 12 km grid used in the Transport Rule, but does not necessarily yield less reliable results. 22 EPA's modeling analysis ofwestern states to identify monitors at risk for maintenance of the 

### 1997 annual PM25 NAAQS identifies only two such maintenance-only receptors, in Los Angeles and Orange Counties, California. These monitors are at least 1,100 miles lI'om North Dakota's closest area (the State's southwestern corner,)23 and mountain ranges between North Dakota and the southern California maintenance receptors, such as the Rocky Mountains, Wasatch and the Sierra Nevada, present large obstacles to PM25 transport from North Dakotato

)U Table IV.C-13, id., at 45255
. .'1 I"or "linkages" betwccn states and maintcnancc-only sites se0 Table IV.C-15, id., at 45259-60. 12 EPA's August 23, 20 I0 mcmo, '"Documentation ofFuture Year Ozonc and Annual PVl2 ) Design Valucs for Western Stutcs," at 5. 2, This distance is cstimat0d on a straight path h'om \:orth Dakota's southwestern cornerto [,os Angcles. Any emissions ii'om North Dakota sources I'eaching the Los Angeles and Orange Counties would travcl a longer distance because the sources would be farther east and/or nOl1h than the State's southwestcrn corner, and because long rangePage 

### 22 01'29 the two maintenance receptors in Los Angeles ai1d Orange Counties. In addition, west ofthe Continental Divide the prevailing winds generally move from south-westerly, westerly, or northwesterly directions, as indicated by the typical movement ofweather systems. Thus, geography, topography and meteorology ofthe region that encompasses North Dakota and Californiamake it unlikely for PM2.5emissions and/or its precursors to contributc significantly to California's maintenance receptors. and thus interfere with maintenance ofthe annual PM25 1997 NAAQS at these receptors. It must also be noted that there arc no maintenance receptors in any ofthc western states adjacent, orrelatively close, to North Dakota, such as Montana, Idaho, Wyoming, and Utah. In fact, 2012 projected design valucs for the annual PM25 peaked in Utah, Montanaand Idaho at concentrations bcIow ]2**~lg/m3,** and in Wyoming at concentrations below ]() f.lg/m3.24 Turning to the 1997 24-hour PM25NAAQS. in the Transport Rule Proposal EPA did not evaluate nonattainment receptors because there were no violations ofthese standards in portions ofthe U.S. covered by the 12 km grid, which includes the 37 states east ofthe Rockies?5 In fact. based on recent monitoringdata (2007-2009 design values that are under final EPA review), the highest 24-hour PM25 design value in 47 ofthe 48 states ofthe continental U.S. (not including California) is 50 f.lg/m3, which is well below the level ofthe ]997 24-hour PM25 NAAQS 01'65**~lg/1l1;.2(' Thercj(.m~.**  outside ofCalifornia, there are no areas that we would expect to have difiiculty in maintaining the 1997 24-hour PMn NAAQS. In California. the most recent (2009)



### _._**_~_** 

# _-_ _---_.._-------­ lransport air parcel pathways rarely follow a straight path. 'I Wcstcrn Statcs Design Valucs (August 23.2010) at 9-1 I. 25 EPA did not model projcctions 10rthe 24-hour PM25 NAAQS in the 36km grid modeling domain. For the statcs included in the Eastcrn domain see Table IV.C-13, Transport Rule Proposal, at 45255. 2(, Data undergoing revicw from EPA's Air Quality System, which is EPA's repository ofambient air quality data.

### Page 23 of29 24-hour PM25

### design values show that the only monitors that might be at risk for maintenance of the 1997 24-hour 

### PYh5 NAAQS are in Turlock, Fresno, and Bakersfield, in the northern, central and southern sections urthe San Joaquin ValIey.27 The high mountain ranges on three sides of the Valley's boundaries (Coast Mountain with 5,000 reet peaks on the west, SierraNevadarange with 14,000 fCet peaks on the east, and Tehachapi Mountains with 6.000 rect along the southern boundary) are an obstacle to transport ofPM2.5 

### and its precursors into the valley. As noted earlier in our discussion ofthe impacts from North Dakotaemissions on annual PM25 

### concentrations, and in this casc too, the geography (nearly 1,200 miles distance), topography (high mountain ranges betwecn North Dakota and California), and meteorology (southwestcrly

or westerly directions orprevailing winds) make it highly unlikely that emissions from North Dakotacontribute significantly to the San Joaquin Valley monitors at risk for maintenance ofthe 24-hourPM25 

### NAAQS. In conclusion, our analysis indicatesthat emissions of

### PI'vhs and/or its precursors from the sources in North Dakota are unlikely to interfere with maintenance orthe 24-hour and the annual PM25 

### NAAQS 

### by any other states.

In the Transport Rule Proposal, EPA projected future concentrations ofozone to identify receptors, referred to as maintenance receptors, that are expected to have difliculty maintaining compliance with the 1997 8-hour ozone NAAQS in 2012. To determine states that impact maintenance-only sites, in the Transport Rule Proposal EPA models the states' ozone

. ---'-_ 

## _._._-_ _-_._ .. ----_..

### _._-_....

### _-- ---_.-

..._-­ (See http://www.epa.gov/ttn/airs/airsaqs/)
.

.'7 The ;\()S preliminary design value data shows that in 200<,) design values at monitors ill these locations rangedPage 24 01'29 contribution to these receptors. For the 8-hourozone NAAQS, EPA identiiied 16 maintenance receptors in its modeling domain. The monitors at risk for maintenance are located in a handful ofstates, including eight monitors in Texas, f(lUr in Connecticut, two in Georgia, and one each in New York and Pennsylvania. 2S The largest contribution from North Dakotaemissionsto the 16 maintenance receptors in these states was estimated to be 0.0 ppb, resulting in the exclusion of the State's emissions from further analysis, and in the conclusion that North Dakota emissions do not interCcre with maintenance orthe 1997 8-hour ozone NAAQS by any states in the eastern U.S.A. As noted earlieL EPA has also developed a modeling analysis identifying maintenance receptors within a modeling domain that includes the western states. 29 In the western states EPA identified only f(lUr monitors at risk for maintenance ofthe 1997 8-hourozone NAAQS, and all f()ur are in California, in Mercer. Placer, Riverside, and Sacramento Counties. Geography and topography are not favorable to ozonetransport from North Dakota, which is approximately 1200 miles northeast ofthe counties referenced above. 1n the absence ofsignificant northeasterly regional transport winds, mountain ranges betweenNorth Dakota and the California maintenance receptors, such as the Rocky Mountains. the Wasatch and the Sierra Nevada, present seriolls obstacles to ozone transport from North Dakotato Calif(JI'nia. Thus, geography and topography reduce the likelihood oftransport from N0l1h Dakotato California's maintenance receptors. Prevailing wind orientation in fact strongly supports the conclusionthat emissions from

---- ---,-----,---, ----_.- .._--­ b'om 60**~lg/m;** in Fresno and Turlock, to 70**~g/m;** in Bakersfield.**2~** Table IV.C-12, Transport Rule Proposal, at 45252-53

### Page 2501'29 North Dakotasources arc unlikely to interfere with maintenance ofthe]997 8-hour ozone standard in California. West ofthe Continental Divide the prevailing winds generally move from south-westerly, westerly, ornorth-westerly directions, as indicated bythe typical movement ofweather systems. To further evaluate the direction ofregional transport winds affecting thc Californiamaintenance receptors, EPA Rcgion 8 has plotted backtrajectories starting at each maintenance receptor on high ozone days. High ozone days include the top one third ofthe exceedance days (for the 1997 8-hourozone NAAQS) registered at each monitor in 2005 and 2006. As shown by the trajectories mapped for all four maintenance receptors in Figure 3.1, Appendix A ofEPA's supporting documentation, on high ozone days air parcels converge onthe Mercer, Placer, Sacramento and Riverside monitors from the northwest, south and southeast, but there are no pathways from the cast/northeast directions reaching even as**t~lr** 

### as the eastern Nevadaborder, let alone North Dakota. For a largenumber ofreceptors in western states, EPA's modeling analysis could not calculate 2012 projected design values because these receptors did not have at least 5 days with base year concentrations equal to or greater than 70 ppb, as required by EPA's modeling guidance. However, the observed maximum design values atthese sites in the 2003-2007 period

were generally well belowthe 1997 ozone NAAQS. Thehighest (non-California30) 

### site had a maximum design value of77 ppb. Additionally, the 2012 modeling results at western monitors

29 Western States Design Values (August 23,20I0). 30 We are excluding the Californiamonitors from this portion ofour analysis because above we have already demonstrated that North Dakota's emissions are unlikely to interfere with maintenance at the modeled California maintenance monitors in the northern, central and southern sections ofthe state. The factors we considered· dIstance, topography, and wind orientation--apply equally to the un-modeled monitors and make it plausible to conclude that the same demonstration is true for North Dakota emissions' impact on California non-modeled monitors.Page 26 of29 (where a future year design value could be estimated,) shows a downward trend in ozone. There

arc no areas in the West where o/:one is predicted to be higher in 2012 (without CAIR) compared to 2005. On these bases it is plausible to conclude that it is highly unlikely, but not impossible, f()f these monitors to be at risk for maintenance ofthe 1997 8-hour ozone NAAQS. In conclusion, data and weight ofevidence analysis presentcd in this section support the position ofthe North Dakota Interstate Transport SIP (adopted into the State SIP on April L 2009 and submitted to EPA ApriI6,2(09) that emissions from North Dakota do not interlCre with maintenance ofthe 1997 8-hour ozone NAAQS by any other state, consistent with the requirements ofclement (2) ofCAA section 110(a)(2)(D)(i). VI. Proposed Action EPA is proposing partial approval ofthe addition to theNorth Dakota SIP ofthe "Interstate Transport ofAir Pollution" SIP addressing the requirements ofCAA section 110(a)(2)(D)(i) for the 1997 PM25 and 8-hour ozone National Ambient Air Quality Standards (NAA()S). r;:PA is proposing approval ofthe language in Section 7.8.1, subsection B., '"Nonattainment and Maintenance Area Impact,"that specifically addresses clement (2) of section 11 O(a)(2)(D)(i), the requirementthat the SIP contain adequate provisions prohibiting emissionsfrom North Dakotafrom interfering with maintenance ofthe 1997 PM25 and 8-hour

ozone NAAQS by any other state. The language in Section 7.8.1, subsection 13., that addresses clement ( 1) ofsection ] 1O(a)(2)(D)(i) was approved by EPA in a June 3, 2010 Federal Register action. VII. Statutory and Executive Order Review Under the Clean Air Act, the Administrator is required to approve a SIP submission thatPage 27 of29 complies with the provisions ofthe Act and applicable Federal regulations. 42 U.S.c. 741 O(k); 40 CFR 52.02(a). Thus, in rcviewing SIP submissions, EPA's role is to approve state choices, provided that they meet the criteria ofthe Clean AirAct. Accordingly, this action merely approves state law as meeting Fcderal requirements and does not impose additional requirements heyond those imposed by state law. Forthat reason, this action:

• Is not a "significantregulatory action" subject to review by the Office ofManagement and Budget underExecutive Order 12866 (58 FR 51735, October4, 1993);

• Does not impose an information,collection burden underthe provisions ofthe Paperwork Reduction Act (44 U.S.C. 3501 etseq.);

• Is certilied as not having a signiticant economic impact on a substantial numberofsmall entities underthe Regulatory Flexibility Act (5 U.S.C. 601 e( seq.);

• Does not contain any unfunded mandate or significantly or uniquely affect small governments, as described in the Unfunded Mandates Reform Act of 1995 (Public Law 104-4);

• Does not have Federalism implications as specified in Executive Order 13132 (64 FR 43255, August 10, 1999);

• Is not an economically significant regulatory action based on health or safety risks subject to Exccutive Order 13045 (62 FR 19885, April 23, 1997);

• Is not a significant regulatory action subjectto Executive Order 13211 (66 FR 2835, May 

### 22, 2(01);Page 2801'29

• Is not subject to requiremcnb ofSection 12(d) ofthe National Technology Transfer and Advancement Act of 1995 (15 U.S.c. 272 note) because application ofthose requirements would be inconsistent with the Clean Air Act; and

• Docs notprovide EPA with the discretionary authority to address, as appropriatc, disproportionate human health orenvironmental cffects, usingpracticable and legally permissible methods, under Executive Order 12898 (59 FR 7629, Fcbruary 16, 19(4). In addition, this rule docs not have tribal implications as specified by Executive Order 13175 (65 FR 67249, November 9, 2000), because the SIP is not approved to apply in Indian country located in thc state, and EPA notes that it will not impose substantial direct costs on tribal governments or prcempt tribal law.

### Page 29 01'29 IDENTIFICATION OF DOCUMENT: Approval and Promulgation ofState Implementation Plan Revisions; State ofNorth Dakota; Interstate Transportof Pollution for the 1997 

### PM2.5 

### and 8-hour OzoneNAAQS: "Interferencewith Maintenance" Requirement. Proposed Rule. (EPA-R08-0AR-2009-0282) Page 29 of29 List ofSubjects in 40 CFR Part 52 Environmental protection, Airpollution control, Incorporation 

### by reference, Intergovernmental relations, Nitrogen dioxide, Ozone, Particulate matter, Reporting and recordkeeping requirements, Volatile Organic Compounds. Authority: 42 U.S.c. 7401 et seq.

# (~ / q /Ie) L-/-._
.**.:.._-!..~::"'_.**

# ~.ewl~:;) Dated: Carol Rushin Acting Regional Administrator Region 8