I~NVIRONMENTAL PROTECTION AGENCY 

40 CFR Part 52 

EPA-R08-0AR-2009-0557; FRLApproval and Promulgation of State Implementation Plan Revisions; State of North 

Dakota; Interstate Transport of Pollution for the 1997 PM2.5 and 8-hour Ozone NAAQS: 

"Interference with Maintenance" Requirements 

AGENCY: Environmental Protection Agency (EPA). 

ACTION: Proposed Rule. 

SU MMARY: The Environmental Protection Agency is proposing partial approval of the State 

Implementation Plan (SIP) revisions called "Interstate Transport of Air Pollution" addressing the 

'"inkrlcrence with maintenance" requirement of Clean 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 the North Dakota Interstate 

Transport SIP sections that address the requirements of section 11 O(a)(2)(D)(i) prohibiting a 

state's emissions from interiCring with maintenance by any other state of the 1997 PM2 5 and 8­

hour ol.one NAAQS. This action is being taken under section 110 of the CAA. 

DATES: Comments must be received on or before IInsc:rt date 30 day~.?Dcr-ill!.Qlic~.iQn in the 

Federal Register]. 

ADDRESSES: Submit your comments, identified hy Docket In No. EPA-R08-0AR-2009­

0557, by one of the 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 FURTHER 
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INFORMATION CONTACT if you arc faxing comments). 

Mail: Callie Videtich, Director, Air Program, 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 of boxed 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 other information whose disclosure is restricted by statute. Do 

not submit information that you consider to be CHI or otherwise protected through 

bl!.I2iLY'{'0!vv.regulations.~.wvor 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 of your comment. If you send an e-mail comment 

directly to EPi\, without going through http://www.regulations.gov, your e-mail address will be 

automatically captured and included as part of the comment that is placed in the public docket 

and made available on the Internet. If you submit an electronic comment, EPA recommends that 

you include your name and other contac1 information in the body of your comment and with any 
Page.") or 29 

disk or CD-ROM you submit. If EPA cannot read your comment due to technical dirticulties 

and cannot contact you for clarification, EPA may not be able to consider your comment. 

Electronic files should avoid the use of special characters, any form of encryption, and be free of 

any defects or viruses. For additional instructions on submitting comments, go to Section 1. 

(Jeneral Information of the SUPPLEMENTARY INFORMATION section of this 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 either electronically in httl2://www.regulations.gov or in hard copy at the Air Program, 

Environmental Protection Agency (EPA), Region 8, Mailcode 8P-AR, 1595 Wynkoop, Denver, 

Colorado 80202-1129. EPA requests that irat all possible, you contact the individual listed in 

the FOR FURTHER INFORMATION CONTACT section to view the hard copy of the 

docket. You may view the hard copy of the docket Monday through Friday, 8:00 a.m. to 4:00 

p.m., excluding Federal holidays. 

FOR FURTHER INFORMATION 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 of this document, we are giving meaning to certain words or initials as follows: 

(i) The words or initials A<,;t or CbA mean or refer to the Clean Air Act. unless the context 
Pagc4of29 

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 or refer to State Implementation Plan. 

(iv) The words NQ.r:!hl)l;lkota and State mean the State of North Dakota. 

Tablc of Contcnts 

I. Gcncral Information 

What Should I Consider as I Prepare My Comments for EPA? 

II. Background 

III. What Action 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 of Interference with Maintenance 

B. North Dakota Transport SIP 

VI. Proposed Action 

VII. StatutoI)' and Executive Order Reviews 

I. General Information 

What should I consider as I prepare my comments for EPA? 

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

inf()rmation in a disk or CD ROM that you mail to EPA, mark the outside of the disk or CD 

ROM as CHI and then identify electronically within the disk or CD ROM the specific 
Page 5 of29 

information that is claimed as CBI. In addition to one complete version of the 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, remember to: 

a.	 Identify the rulemaking by docket number and other identifying information 

(subject heading, Federal Register date and page number). 

b.	 Follow directions - The agency may ask you to respond to specific questions or 

organize comments by referencing a Code of Federal Regulations (CFR) part or 

section number. 

c.	 Explain why you agree or disagree; suggest alternatives and substitute language 

for your requested changes. 

d.	 Describe any assumptions and provide any technical information and/or data that 

you used. 

e.	 If you estimate potential costs or burdens, explain how you 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, avoiding the usc of profanity or 

personal threats. 

h.	 Make sure to submit your comments by the comment period deadline identified. 

I I. Background 

On July 18, 1997, EPA promulgated new NAAQS for ozone and for PM2 ). This action 
Page 6 oC29 

is being taken in response to the promulgation of the 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 later actions. 

Section 11 O(a)( 1) of the Ci\i\ requires states to submit SIPs to address a new or revised 

Ni\i\QS within 3 years after promulgation of such standards, or within such shorter period as 

l~Pi\ may prescribe. Section 110(a)(2) lists the clements that such new SIPs must address, as 

applicable, including section 11 0(a)(2)(D)(i), which pertains to interstate transport of certain 

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 of section 11 0(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 

II O(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 of interstate transp0l1. The S[P must prevent sources 

in the state from emitting pollutants in amounts which will: (1) contribute significantly to 

nonattainment of the Ni\AQS in other states; (2) interfere with maintenance of the Ni\AQS in 

other states; (3) interfere with provisions to prevent significant deterioration of air 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 to 
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address the requirements of section II O(a)(2)(D)(i) j~)r both the 1997 8-hour ozonc 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 of 0iorth Dakota indicated that its current SIP is adequate to prevent 

such interference. With this submission, the state intended to meet the recommendations of the 

2006 Guidance for SIP submissions to meet thc second element of scction II 0(a)(2)(D)(i) for the 

1997 PM25 and 8-hour 070ne standards. 

Ill. What Action Is EPA Proposing? 

EPA is proposing partial approval or the North Dakota Interstate Transport of Air 

Pollution SIP for the 1997 PM25 and 8-hour ozone NAAQS. The addition to thc North Dakota 

SIP of section 7.8, "Interstate Transport of Air Pollution," was adopted by the State of North 

Dakota on April I, 2009 and submitted to EPA on April 6, 2009. EPA is proposing to approve 

the language and demonstrations of the North Dakota Interstate Transport SIP that address 

clement (2) of section II 0(a)(2)(D)(i), i.e .. the prohibition of interference with maintenance of 

the 1997 8-hour ozone NAAQS and the 1997 PM25 NAAQS by any other statc. 

IY. What Is the State Process to Submit This Material to EPA? 

Section II O(k) of the 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 of Health (NDDH) held a public hearing on October 7, 

2008 for the addition to the North Dakota SIP of the 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 11 0(a)(2) of the CAl\. 

v. EPA's Review and Technical Information 

A. EPA's Evaluation of Interference with Maintenance 

The second dement of section II 0(a)(2)(D)(i) requires that a state's SIP must prohibit 

any source or other type of emissions activity in the state from emitting pollutants that would 

"interCcre with maintenance" of the 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 of NOx that 

significantly contributed to nonattainment, or interfered with maintenance of, the then applicable 

ozone NAAQS through interstate transport of NOx 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 if they 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 of the 1997 8-hour ozone 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 of S02 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 

of the evaluation of whether or not the emissions of sources in certain states had such impacts on 

areas that EPA determined would either be in violation of the NAAQS, or would be in jeopardy 

of violating 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 eliminate the SOz and NOx emissions, 

whether through participation in a regional cap and trade program or by other means. 

EPA's 2006 Guidance addressed section 11 0(a)(2)(D)(i) requirements for the 1997 8­

hour ozone NAAQS and 1997 PMZ5 NAAQS. For those states subject to CAlK EPA indicated 

that compliance with CArR would meet the two requirements of section 11 0(a)(2)(D)(i)(I) for 

these NAAQS. For states not within the CArR region, EPA recommended that states evaluate 

whether or not emissions from their sources would "interfere with maintenance" by other states, 

following the conceptual approach adopted by EP A in CAIR. After recommending various types 

of information that could be relevant for the technical analysis to support the SIP submission, 

such as the amount of em issions and meteorological conditions in the state, EPA further 

indicated that it would he appropriate for the state to assess impacts of its emissions on other 

states using considerations comparable to those used by EPA "in evaluating signi f'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 of section 11 0(a)(2)(D)(i) together without explicitly differentiating between them. 

In 2008, however, the U.S. Court of Appeals 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 of section 11 0(a)(2)(D)(i)(l) in 

CAIR. The court noted that "EPA gave no independent significance to the 'interfere with 

maintenance' prong of section 11 0(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 eoncl udcd that a plain language reading of the statute requires EPA 

to give independent meaning to the interfere with maintenance requirement of section 

I 10(a)(2)(D) and that the approach used by EPA in CAIR failed 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 respect to 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 Dakota developed and adopted their Interstate Transport SIP not long after the 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. 

I 
Page 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 of the statute, and relied in a general way on the difference between monitored 

concentrations and the 1997 8-hour ozone NAAQS to evaluate the impacts of State emissions on 

maintenance of the NAAQS in neighboring states. EPA believes that it is necessary to evaluate 

these state submissions for section II O(a)(2)(D)(i)(l) in such a way as to assure that the interfere 

with maintenance clement of the statute is givcn independent meaning and is appropriately 

evaluated using the types of information 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 of section 11 O(a)(2)(D)(i). 

EPA has recently proposed a new rule to address interstate transport pursuant to section 

I IO(a)(2)( D)(i), the "Federal Implementation Plans to Reduce Interstate Transport of Fine 

Particulate Matter and Ozone" (Transport Rule Proposal), in order to address the judicial remand 

ofCAIR. 7 As part of the Transport Rule Proposal, EPA specifically reexamined the section 

II 0(a)(2)(D) requirement that emissions from sources in a state must not "interfere with 

maintenance" of the 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-hour ozone ;,\AAQS and 1997 PM2 'i NAAQS in the future. and therefore at risk to 

-_.....---_..._...- ...-.-.--­

7 See "Federal Implementation Plans to Reduce Interstate Transport of Fine [)articulate \t1atter and Ozone," 75 FR 

45210 (August 2. 20) 0). 
P~lge 12 of29 

become or continue 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, rather than with significant 

contri bution to nonattainment. 

As described in more detail below, LPNs analysis evaluates data from existing monitors 

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

as air quality modeling data, in order to determine which areas are predicted to be violating the 

1997 8-hour ozone and PM25 NAAQS in 2012, and which areas are predicted potentially to have 

difficulty with maintaining attainment as of that date. In essence, ifan area's projected data (I)r 

2012 indicates that it would be violating the l\JAAQS based on the average of these three 

overlapping periods, then this monitor location is appropriate j~)r comparison for purposes of the 

significant contribution to nonattainment clement of section 11 0(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 over the average of the three periods, then this monitor location is appropriate fl)!" 

comparison for purposes of the intericrence with maintenance element of the statute. 

By this method, EPA has identilied those areas with monitors that arc appropriate 

""maintenance-only sites" or maintenance "receptors'" ior evaluating whether the emissions from 

sources in another state could interfere with maintenance in that particular area. f':P A then uses 

other analytical tools to examine the potential impacts of emissions from upwind states on these 

maintenance receptors in downwind states. L~P A believes that this new approach fl)r identi eying 
Page 13 of29 

those areas that arc predicted to have maintenance problems is appropriate to eval uate the section 

11 O(a)(2)(D)(i) SIP submission or a state for the interference with maintenance element.s F:PA's 

2006 Cjuidance did not provide this specific recommendation to states, but in light of the court's 

decision on CAIR, I':[>A will itselfrollow this 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 precisely the same analytical approach 

as CAIR. In the 2006 Guidance, EPA stated that: "EPA believes that the contents of the SIP 

submission required by section 110(a)(2)(D)(i) may vary depending upon the facts and 

circumstances related 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 or revised NAAQS 

necessarily arTects the contents of the 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 continues to belicvc that thc morc 

widcspread and serious transport problems in the castern United States arc analytically distinct. 

For the 1997 8-hour ozone NAAQS and the 1997 PM25 NAAQS, EPA believes that 

nonattainment and maintenance problems in the western United States are relatively local in 

--_..._.__.­

x To 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 :W 12. 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 of the "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 or from western States. 

Accordingly, EPA believes that section 11O(a)(2)(D)(i) SIP submissions Cor states not 

evaluated in the Transport Rule Proposal may be evaluated using a "weight of the 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 of emissions 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 of the 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 if other available information is suHicient to evaluate thc presence or degree 

of interstate 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 

of the Rockies, from North Dakota in the north to Texas in the south and eastward, and its 

analysis results include estimates of North 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 whether emissions from North 

II Scc, Transport Rule Proposal, 75 FR 45210, /1,5277. 
Page 1501'29 

Dakota interfere with maintenance of the NAAQS by any other states we use these estimated 

contributions in combination with other types of information 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 of section 11 O(a)(2)(D)(i), the State of North Dakota on April 

6, 2009 made a SIP submission to EPA addressing interstate transport for the 1997 PM25 and the 

8-hour ozone NAAQS. EPA has previously approved this submission for purposes of the 

significant contribution to nonattainment and of the interference with PSD clements of section 

110(a)(2)(D)(i).12 The State's submittal focused primarily on whether emissions from North 

Dakota sources signilicantly contribute to nonattainmcnt of the 1997 8-hour ozone NAAQS and 

1997 PM25 NAAQS in other states. Following the 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 of these NAAQS by other states separately from significant 

contribution to nonattainment in other states. Instead, the State presumed that if North Dakota 

sources were not significantly contributing to violations of the NAAQS in other states, then no 

further specific evaluation was necessary for purposes of the interference with maintenance 

clement of section 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 of EPA's new 

interpretation. We therefore discuss in more detail the approach of the Transport Rule Proposal 

and apply it to our assessment of whether North Dakota's emissions interfere with maintenance 

of the relevant NAAQS by any other states. 

Below, we discuss in greater detail relevant methods and techniques ofthe Transpoli 

Rule ProposaL followed by our assessment of whether emissions from North Dakota interfere 

with maintenance of the 1997 PM25 and 8-hour ozone NAAQS. 

On July 6, 2010, the EPA Administrator signed a proposed rule in response to the judicial 

remand of CAIR. The Transport Rule Proposal, published August 2,20 I0, includes a new 

approach to determine whether emissions from a state interfere with maintenance ofthe 1997 8­

hour ozone NAAQS and the 1997 PM2j NAAQS by other states. In this action, EPA is using 

modeling results from the Transport Rule Proposal to assess whether North Dakota emissions 

interfere with maintenance of the 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 of ozone and PM2 5 

at monitors to identify areas that are expected to be out of attainment 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 of future air quality at existing ozone and PM25 monitoring 

sites in those locations. EPA then used these sites as the receptors for eXamining the 
Page 1701'29 

contributions of emissions from sources located in upwind states to nonattainment and 

maintenance problems at these monitoring locations. 

For ozone, EPA evaluated air quality, 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 if the 3-year average of the 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-year average 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 of the 

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 of the 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-year average 98th 

percentile concentration is referred to as the 24-hour average 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 of this action, is met when the 3-year avcrage of thc 

'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 of the 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 

conccntrations to project concentrations anticipated in 2012 to determine which monitoring sites 

are expected to be nonattainment in this future year. EPA also projected 2012 design val ues 

based on each of the 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 of potential 

variability in future projections due to differences in actual meteorology and emissions from 

what was modeled. 

EPA identified those sites that are projected to be attainment based on the S-year 

weighted average design value, but that have a maximum design value (based on a single three 

year period) that exceeds the NAAQS. 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 of the NAAQS at these locations if there ar~ adverse 

variations in meteorology or emissions. These projected maintenance sites arc the ones that EPA 

has used to determine if emissions from North Dakota sources potentially interfere with 

maintenance of the 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 air quality modeling, contributions from individual states to 

downwind maintenance receptors. States whose contributions to any downwind receptors which 

arc above the "signi ficant contribution" threshold, one percent of the relevant NAi\QS, are 

considered "linked" to thosc receptors for the purpose of the second step. In the second step, 

EPA uses maximum cost thresholds, infoTIncd by air quality considerations, to detennine the 

portion of each 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 percent ofthe Ni\AQS for both PM2 ) and ozone. III For the 1997 annual PM2.) EPA 

proposed in the Transport Rule Proposal a threshold of 0.15 ).tg/m3

, without any further rounding 

up. I? States contributing less than 0.15 ).tg/m3to downwind maintcnance receptors are below the 

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 which the affected receptors are 

located. States with "linkages" to downwind maintenance receptors are included in the 

analytical process that determines the controls (if any) requircd for compliance with the 

"interference with maintenance" element of scction 11 O(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)
 

(J une 2{) I0). Dvai lab Ie at Regulat ions.gov as Document ID No. EPA-I IQ-OAR-2009-049 1-0047. For greater detai I
 

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 orair quality 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 of the NAAQS. State contributions 

or 0.8 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 (if any) required of such states to satisfy the "interfere with 

maintenance" clement of section 11 O(a)(2)(D)(i) for the 1997 8-hour ozone standard. IX 

In the Transport Rule Proposal, EPA projected future concentrations of PM25 to identi l'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. For the 1997 annual PM25 

NAAQS, the Transport Rule Proposal identified 16 maintenance receptors in its modeling 

domain. The monitors at risk ror maintenance are located in seven states. including two 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 45248 
Pagc 2101'29 

two thirds below the "significant contribution" threshold of 0.15 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 of the monitors at risk 

for maintenance of the NAAQS. 21 

To assist in the evaluation of whether emissions from a state's sources interfere with 

maintenance of the NAAQS in western states, EPA has developed, independent of the Transport 

Rule ProposaL a modeling analysis identifying monitors at risk for maintenance of the NAAQS 

within a modeling domain that includes the western states. The analysis presented in the memo, 

"Documentation of Future Ycar Ozone 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 of western 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 Dakota to 

)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 of Future Year Ozonc and Annual PVl 2 ) Design Valucs for 

Western Stutcs," at 5. 

2, This distance is cstimat0d on a straight path h'om \:orth Dakota's southwestern corner to [,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 range 
Page 22 01'29 

the two maintenance receptors in Los Angeles ai1d Orange Counties. In addition, west of the 

Continental Divide the prevailing winds generally move from south-westerly, westerly, or northwesterly directions, as indicated by the typical movement of weather systems. Thus, geography, 

topography and meteorology of the region that encompasses North Dakota and California make 

it unlikely for PM2.5 emissions and/or its precursors to contributc significantly to California's 

maintenance receptors. and thus interfere with maintenance of the annual PM2 5 1997 NAAQS at 

these receptors. 

It must also be noted that there arc no maintenance receptors in any ofthc western states 

adjacent, or relatively close, to North Dakota, such as Montana, Idaho, Wyoming, and Utah. In 

fact, 2012 projected design valucs for the annual PM25 peaked in Utah, Montana and Idaho at 

concentrations bcIow ]2 ~lg/m3, and in Wyoming at concentrations below ]() f.lg/m3.24 

Turning to the 1997 24-hour PM2 5NAAQS. in the Transport Rule Proposal EPA did not 

evaluate nonattainment receptors because there were no violations of these standards in portions 

of the U.S. covered by the 12 km grid, which includes the 37 states east of the Rockies?5 In fact. 

based on recent monitoring data (2007-2009 design values that are under final EPA review), the 

highest 24-hour PM25 design value in 47 of the 48 states of the continental U.S. (not including 

California) is 50 f.lg/m3, which is well below the level of the ]997 24-hour PM25 NAAQS 01'65 

~lg/1l1;.2(' Thercj(.m~. outside of California, 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 of ambient 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, Sierra Nevada range 

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 of the impacts from North Dakota emissions 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 or prevailing winds) make it highly unlikely that emissions from North 

Dakota contribute significantly to the San Joaquin Valley monitors at risk for maintenance ofthe 

24-hour PM25 NAAQS. 

In conclusion, our analysis indicates that emissions of PI'vhs and/or its precursors from 

the sources in North Dakota are unlikely to interfere with maintenance or the 24-hour and the 

annual PM25 NAAQS by any other states. 

In the Transport Rule Proposal, EPA projected future concentrations of ozone 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 ranged 
Page 24 01'29 

contribution to these receptors. For the 8-hour ozone NAAQS, EPA identiiied 16 maintenance 

receptors in its modeling domain. The monitors at risk for maintenance are located in a handful 

of states, 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 Dakota emissions to 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 or the 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 of the 1997 8-hour ozone NAAQS, and all 

f()ur are in California, in Mercer. Placer, Riverside, and Sacramento Counties. Geography and 

topography are not favorable to ozone transport from North Dakota, which is approximately 

1200 miles northeast of the counties referenced above. 1n the absence of significant 

northeasterly regional transport winds, mountain ranges between North 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 Dakota to Calif(JI'nia. Thus, 

geography and topography reduce the likelihood of transport from N0l1h Dakota to California's 

maintenance receptors. 

Prevailing wind orientation in fact strongly supports the conclusion that 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 Dakota sources arc unlikely to interfere with maintenance of the] 997 8-hour ozone 

standard in California. West of the Continental Divide the prevailing winds generally move 

from south-westerly, westerly, or north-westerly directions, as indicated by the typical movement 

of weather systems. To further evaluate the direction ofregional transport winds affecting thc 

California maintenance receptors, EPA Rcgion 8 has plotted back trajectories starting at each 

maintenance receptor on high ozone days. High ozone days include the top one third of the 

exceedance days (for the 1997 8-hour ozone 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 of EPA's supporting documentation, on high ozone days air parcels converge on the 

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 

Nevada border, let alone North Dakota. 

For a large number of receptors 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 at these sites in the 2003-2007 period 

were generally well below the 1997 ozone NAAQS. The highest (non-California30

) site had a 

maximum design value of 77 ppb. Additionally, the 2012 modeling results at western monitors 

29 Western States Design Values (August 23,20 I 0). 

30 We are excluding the California monitors from this portion of our 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 of the 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 of the 1997 8-hour ozone NAAQS. 

In conclusion, data and weight of evidence analysis presentcd in this section support the 

position of the North Dakota Interstate Transport SIP (adopted into the State SIP on April L 

2009 and submitted to EPA Apri I 6,2(09) that emissions from North Dakota do not interlCre 

with maintenance of the 1997 8-hour ozone NAAQS by any other state, consistent with the 

requirements of clement (2) of CAA section 11 0(a)(2)(D)(i). 

VI. Proposed Action 

EPA is proposing partial approval of the addition to the North Dakota SIP ofthe 

"Interstate Transport of Air Pollution" SIP addressing the requirements of CAA 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 of the 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 requirement that the SIP contain adequate provisions prohibiting 

emissions from North Dakota from interfering with maintenance of the 1997 PM25 and 8-hour 

ozone NAAQS by any other state. The language in Section 7.8.1, subsection 13., that addresses 

clement ( 1) of section ] 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 that 
Page 27 of29 

complies with the provisions of the 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 of the Clean Air Act. Accordingly, this action merely 

approves state law as meeting Fcderal requirements and does not impose additional requirements 

heyond those imposed by state law. For that reason, this action: 

•	 Is not a "significant regulatory action" subject to review by the Office of Management 

and Budget under Executive Order 12866 (58 FR 51735, October 4, 1993); 

•	 Does not impose an information, collection burden under the provisions of the Paperwork 

Reduction Act (44 U.S.C. 3501 et seq.); 

•	 Is certi lied as not having a signiticant economic impact on a substantial number of small 

entities under the 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 subject to Executive Order 13211 (66 FR 2835, May 

22, 2(01); 
Page 2801'29 

•	 Is not subject to requiremcnb of Section 12(d) of the National Technology Transfer and 

Advancement Act of 1995 (15 U.S.c. 272 note) because application of those 

requirements would be inconsistent with the Clean Air Act; and 

•	 Docs not provide EPA with the discretionary authority to address, as appropriatc, 

disproportionate human health or environmental cffects, using practicable 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 of State 

Implementation Plan Revisions; State of North Dakota; Interstate Transport of 

Pollution for the 1997 PM2.5 and 8-hour Ozone NAAQS: "Interference with 

Maintenance" Requirement. Proposed Rule. (EPA-R08-0AR-2009-0282) Page 29 of 29 

List of Subjects in 40 CFR Part 52 

Environmental protection, Air pollution 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