45242 Federal Register / Vol. 82, No. 187 / Thursday, September 28, 2017 / Proposed Rules 

Dated: September 8, 2017. 

Cecil Rodrigues, 

Acting Regional Administrator, Region III. 

[FR Doc. 2017–20723 Filed 9–27–17; 8:45 am] 

BILLING CODE 6560–50–P 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 52 

[EPA–R01–OAR–2017–0083; FRL–9968–43– 

Region 1] 

Air Plan Approval; New Hampshire; 

Nonattainment Plan for the Central 

New Hampshire SO2 Nonattainment 

Area 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Proposed rule. 

SUMMARY: The Environmental Protection 

Agency (EPA) is proposing to approve 

the State Implementation Plan (SIP) 

revision that the State of New 

Hampshire submitted to EPA on January 

31, 2017 for attaining the 1-hour sulfur 

dioxide (SO2) primary national ambient 

air quality standard (NAAQS) for the 

Central New Hampshire Nonattainment 

Area. This plan (herein called a 

‘‘nonattainment plan’’) includes New 

Hampshire’s attainment demonstration 

and other elements required under the 

Clean Air Act (CAA). In addition to an 

attainment demonstration, the 

nonattainment plan addresses the 

requirement for meeting reasonable 

further progress (RFP) toward 

attainment of the NAAQS, reasonably 

available control measures and 

reasonably available control technology 

(RACM/RACT), base-year and 

projection-year emission inventories, 

and contingency measures. As a part of 

approving the attainment 

demonstration, EPA is also proposing to 

approve SO2 emission limits and 

associated compliance parameters for 

Merrimack Station into the New 

Hampshire SIP. EPA proposes to 

conclude that New Hampshire has 

appropriately demonstrated that the 

nonattainment plan provisions provide 

for attainment of the 2010 1-hour 

primary SO2 NAAQS in the Central New 

Hampshire Nonattainment Area by the 

applicable attainment date and that the 

nonattainment plan meets the other 

applicable requirements under the CAA. 

DATES: Comments must be received on 

or before October 30, 2017. 

ADDRESSES: Submit your comments, 

identified by Docket ID No. EPA–R01– 

OAR–2017–0083 at http://

www.regulations.gov, or via email to 

biton.leiran@epa.gov. For comments 

submitted at Regulations.gov, follow the 

online instructions for submitting 

comments. Once submitted, comments 

cannot be edited or removed from 

Regulations.gov. For either manner of 

submission, EPA may publish any 

comment received to its public docket. 

Do not submit electronically any 

information you consider to be 

Confidential Business Information (CBI) 

or other information whose disclosure is 

restricted by statute. Multimedia 

submissions (audio, video, etc.) must be 

accompanied by a written comment. 

The written comment is considered the 

official comment and should include 

discussion of all points you wish to 

make. EPA will generally not consider 

comments or comment contents located 

outside of the primary submission (i.e., 

on the web, cloud, or other file sharing 

system). For additional submission 

methods, please contact the person 

identified in the FOR FURTHER

INFORMATION CONTACT section. For the 

full EPA public comment policy, 

information about CBI or multimedia 

submissions, and general guidance on 

making effective comments, please visit 

http://www.epa.gov/dockets/ 

commenting-epa-dockets. 

FOR FURTHER INFORMATION CONTACT: 

Leiran Biton, EPA New England, 5 Post 

Office Square Suite 100, Mail Code 

OEP05–2, Boston, MA 02109–3912; 

phone: 617–918–1267; fax: 617–918– 

0267; email: biton.leiran@epa.gov. 

SUPPLEMENTARY INFORMATION: 

Throughout this document whenever 

‘‘we,’’ ‘‘us,’’ or ‘‘our’’ is used, we mean 

EPA. 

Table of Contents 

I. Why was New Hampshire required to 

submit an SO2 plan for the Central New 

Hampshire Nonattainment area? 

II. Requirements for SO2 Nonattainment Area 

Plans 

III. Attainment Demonstration and LongerTerm Averaging 

IV. Review of Modeled Attainment Plan 

A. Model Selection and Modeling 

Components 

B. Area of Analysis 

C. Receptor Grid 

D. Meteorological Data 

E. Source Characterization 

F. Emissions Data 

G. Emission Limits 

1. Enforceability 

2. Longer-Term Average Limits 

H. Background Concentrations 

I. Summary of Results 

V. Review of Other Plan Requirements 

A. Emissions Inventory 

B. RACM/RACT 

C. New Source Review (NSR) 

D. Reasonable Further Progress (RFP) 

E. Contingency Measures 

VI. Additional Elements of New Hampshire’s 

Submittal 

A. Conformity 

B. Changes in Allowable Emissions 

C. Air Quality Trends 

D. Compliance With Section 110(a)(2) of 

the CAA 

E. Equivalency Techniques 

VII. EPA’s Proposed Action 

VIII. Incorporation by Reference 

IX. Statutory and Executive Order Reviews 

I. Why was New Hampshire required to 

submit an SO2 plan for the Central New 

Hampshire Nonattainment area? 

On June 22, 2010, EPA promulgated a 

new 1-hour primary SO2 NAAQS of 75 

parts per billion (ppb), which is met at 

an ambient air quality monitoring site 

when the 3-year average of the annual 

99th percentile of 1-hour daily 

maximum concentrations does not 

exceed 75 ppb, as determined in 

accordance with appendix T of 40 CFR 

part 50. See 75 FR 35520, codified at 40 

CFR 50.17(a)–(b). On August 5, 2013, 

EPA designated a first set of 29 areas of 

the country as nonattainment for the 

2010 SO2 NAAQS, including the Central 

New Hampshire Nonattainment Area 

within the State of New Hampshire. See 

78 FR 47191, codified at 40 CFR part 81, 

subpart C. These area designations were 

effective October 4, 2013. Section 191 of 

the CAA directs states to submit SIPs for 

areas designated as nonattainment for 

the SO2 NAAQS to EPA within 18 

months of the effective date of the 

designation, i.e., by no later than April 

4, 2015 in this case. These SIPs are 

required to demonstrate that their 

respective areas will attain the NAAQS 

as expeditiously as practicable, but no 

later than 5 years from the effective date 

of designation, which is October 4, 

2018. 

For a number of areas, including the 

Central New Hampshire Nonattainment 

Area, EPA published a notice on March 

18, 2016 that New Hampshire and other 

pertinent states had failed to submit the 

required SO2 nonattainment plan by the 

submittal deadline. See 81 FR 14736. 

This finding initiated a deadline under 

CAA section 179(a) for the potential 

imposition of new source and highway 

funding sanctions, and for EPA to 

promulgate a federal implementation 

plan (FIP) under section 110(c) of the 

CAA. In response to the requirement for 

SO2 nonattainment plan submittals, 

New Hampshire submitted a 

nonattainment plan for the Central New 

Hampshire Nonattainment Area on 

January 31, 2017. Pursuant to New 

Hampshire’s January 31, 2017 submittal 

and EPA’s subsequent letter dated 

March 20, 2017 to New Hampshire 

finding the submittal complete and 

noting the stopping of the sanctions 

deadline, these sanctions under section 

179(a) will not be imposed. However, to 


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stop the deadline for EPA to promulgate 

a FIP, the state must have made the 

necessary complete submittal and EPA 

must have approved the submittal as 

meeting applicable requirements no 

later than two years after the prior 

finding of failure to submit. Therefore, 

EPA remains under a FIP deadline of 

April 18, 2018. This FIP obligation will 

not apply if EPA issues final approval 

of New Hampshire’s SIP submittal by 

April 18, 2018. 

The remainder of this preamble 

describes the requirements that 

nonattainment plans must meet in order 

to obtain EPA approval, provides a 

review of the State’s plan with respect 

to these requirements, and describes 

EPA’s proposed action on the plan. 

II. Requirements for SO2

Nonattainment Area Plans 

Nonattainment SIPs must meet the 

applicable requirements of the CAA, 

and specifically CAA sections 110, 172, 

191 and 192. EPA’s regulations 

governing nonattainment SIPs are set 

forth at 40 CFR part 51, with specific 

procedural requirements and control 

strategy requirements residing at 

subparts F and G, respectively. Soon 

after Congress enacted the 1990 

Amendments to the CAA, EPA issued 

comprehensive guidance on SIPs in a 

document entitled, ‘‘General Preamble 

for the Implementation of Title I of the 

Clean Air Act Amendments of 1990,’’ 

published at 57 FR 13498 (April 16, 

1992) (General Preamble). Among other 

things, the General Preamble addressed 

SO2 SIPs and fundamental principles for 

SIP control strategies. Id., at 13545–49, 

13567–68. On April 23, 2014, EPA 

issued recommended guidance for 

meeting the statutory requirements in 

SO2 SIPs, in a document entitled, 

‘‘Guidance for 1-Hour SO2

Nonattainment Area SIP Submissions,’’ 

available at https://www.epa.gov/sites/ 

production/files/2016-06/documents/ 

20140423guidance_nonattainment_

sip.pdf. In this guidance, EPA described 

the statutory requirements for a 

complete nonattainment area SIP, which 

includes: An accurate emissions 

inventory of current emissions for all 

sources of SO2 within the 

nonattainment area, an attainment 

demonstration, demonstration of RFP, 

implementation of RACM (including 

RACT), an approvable NSR program, 

enforceable emissions limitations and 

control measures as needed for timely 

attainment, and adequate contingency 

measures for the affected area. 

In order for EPA to fully approve a 

SIP as meeting the requirements of CAA 

sections 110, 172, 191, and 192, and 

EPA’s regulations at 40 CFR part 51, the 

SIP for the affected area needs to 

demonstrate to EPA’s satisfaction that 

each of the aforementioned 

requirements has been met. Under CAA 

sections 110(l) and 193, EPA may not 

approve a SIP that would interfere with 

any applicable requirement concerning 

NAAQS attainment and RFP, or any 

other applicable requirement under the 

CAA. Furthermore, no requirement in 

effect, or required to be adopted by an 

order, settlement, agreement, or plan in 

effect before November 15, 1990, in any 

nonattainment area for any air pollutant, 

may be modified in any manner unless 

it ensures equivalent or greater emission 

reductions of such air pollutant. 

III. Attainment Demonstration and 

Longer-Term Averaging 

CAA sections 172(c)(1) and (6) direct 

states with areas designated as 

nonattainment to demonstrate that the 

submitted plan provides for attainment 

of the NAAQS. Forty CFR part 51, 

subpart G further delineates the control 

strategy requirements that SIPs must 

meet, and EPA has long required that all 

SIPs and control strategies reflect four 

fundamental principles of 

quantification, enforceability, 

replicability, and accountability. See 

General Preamble, at 13567–68. SO2

attainment plans must consist of two 

components: (1) Emission limits and 

other control measures that assure 

implementation of permanent, 

enforceable, and necessary emission 

controls; and (2) a modeling analysis 

that meets the requirements of 40 CFR 

part 51, appendix W (the Guideline on 

Air Quality Models; ‘‘the Guideline’’) 

and demonstrates that these emission 

limits and control measures provide for 

timely attainment of the primary SO2

NAAQS as expeditiously as practicable, 

but by no later than the attainment date 

for the affected area. In all cases, the 

emission limits and control measures 

must be accompanied by appropriate 

methods and conditions to determine 

compliance with the respective 

emission limits and control measures 

and must be quantifiable (i.e., a specific 

amount of emission reduction can be 

ascribed to the measures), fully 

enforceable (specifying clear, 

unambiguous, and measurable 

requirements for which compliance can 

be practicably determined), replicable 

(the procedures for determining 

compliance are sufficiently specific and 

non-subjective so that two independent 

entities applying the procedures would 

obtain the same result), and accountable 

(source specific limits must be 

permanent and must reflect the 

assumptions used in the SIP 

demonstrations). 

EPA’s April 2014 guidance 

recommends that the emission limits be 

expressed as short-term average limits 

(e.g., addressing emissions averaged 

over one or three hours), but also 

describes the option to utilize emission 

limits with longer averaging times of up 

to 30 days so long as the state meets 

various suggested criteria. See April 

2014 guidance, pp. 22 to 39. The 

guidance recommends that—should 

states and sources utilize longer 

averaging times—the longer-term 

average limit should be set at an 

adjusted level that reflects a stringency 

comparable to the 1-hour average limit 

at the critical emission value shown to 

provide for attainment that the plan 

otherwise would have set. 

The April 2014 guidance provides an 

extensive discussion of EPA’s rationale 

for concluding that appropriately set 

comparably stringent limitations based 

on averaging times as long as 30 days 

can be found to provide for attainment 

of the 2010 SO2 NAAQS. In evaluating 

this option, EPA considered the nature 

of the standard, conducted detailed 

analyses of how 30-day average limits 

impact attainment of the standard, and 

carefully reviewed how best to achieve 

an appropriate balance among the 

various factors that warrant 

consideration in judging whether a 

state’s plan provides for attainment. Id. 

at pp. 22 to 39. See also id. at 

appendices B, C, and D. 

As specified in 40 CFR 50.17(b), the 

1-hour primary SO2 NAAQS is met at an 

ambient air quality monitoring site 

when the 3-year average of the annual 

99th percentile of daily maximum 1- 

hour concentrations is less than or equal 

to 75 parts per billion. In a year with 

365 days of valid monitoring data, the 

99th percentile would be the fourth 

highest daily maximum 1-hour value. 

The 2010 SO2 NAAQS, including this 

form of determining compliance with 

the standard, was upheld by the U.S. 

Court of Appeals for the District of 

Columbia Circuit in Nat’l Envt’l Dev. 

Ass’n’s Clean Air Project v. EPA, 686 

F.3d 803 (D.C. Cir. 2012). Because the 

standard has this form, a single 

exceedance does not create a violation 

of the standard. Instead, at issue is 

whether a source operating in 

compliance with a properly set longerterm average could cause exceedances, 

and if so what the resulting frequency 

and magnitude of such exceedances will 

be, and in particular whether EPA can 

have reasonable confidence that a 

properly set longer-term average limit 

will provide that the average fourth 

highest daily maximum value will be at 

or below 75 ppb. A synopsis of how 

EPA judges whether such plans 


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1An ‘‘average year’’ is used to mean a year with 

average air quality. While 40 CFR 50 appendix T 

provides for averaging three years of 99th percentile 

daily maximum values (e.g., the fourth highest 

maximum daily concentration in a year with 365 

days with valid data), this discussion and an 

example below uses a single ‘‘average year’’ in order 

to simplify the illustration of relevant principles. 

‘‘provide for attainment,’’ based on 

modeling of projected allowable 

emissions and in light of the form of the 

NAAQS for determining attainment at 

monitoring sites, follows. 

For plans for SO2 based on 1-hour 

emission limits, the standard approach 

is to conduct modeling using fixed 

emission rates. The maximum emission 

rate that would be modeled to result in 

attainment (i.e., in an ‘‘average year’’ 1

shows three, not four days with 

maximum hourly levels exceeding 75 

ppb) is labeled the ‘‘critical emission 

value.’’ The modeling process for 

identifying this critical emission value 

inherently considers the numerous 

variables that affect ambient 

concentrations of SO2, such as 

meteorological data, background 

concentrations, and topography. In the 

standard approach, the state would then 

provide for attainment by setting a 

continuously applicable 1-hour 

emission limit at this critical emission 

value. 

EPA recognizes that some sources 

have highly variable emissions, for 

example due to variations in fuel sulfur 

content and operating rate, that can 

make it extremely difficult, even with a 

well-designed control strategy, to ensure 

in practice that emissions for any given 

hour do not exceed the critical emission 

value. EPA also acknowledges the 

concern that longer-term emission limits 

can allow short periods with emissions 

above the critical emission value, 

which, if coincident with 

meteorological conditions conducive to 

high SO2 concentrations, could in turn 

create the possibility of a NAAQS 

exceedance occurring on a day when an 

exceedance would not have occurred if 

emissions were continuously controlled 

at the level corresponding to the critical 

emission value. However, for several 

reasons, EPA believes that the approach 

recommended in our guidance 

document suitably addresses this 

concern. First, from a practical 

perspective, EPA expects the actual 

emission profile of a source subject to 

an appropriately set longer-term average 

limit to be similar to the emission 

profile of a source subject to an 

analogous 1-hour average limit. EPA 

expects this similarity because it has 

recommended that the longer-term 

average limit be set at a level that is 

comparably stringent to the otherwise 

applicable 1-hour limit (reflecting a 

downward adjustment from the critical 

emission value) and that takes the 

source’s emission profile into account. 

As a result, EPA expects either form of 

emission limit to yield comparable air 

quality. 

Second, from a more theoretical 

perspective, EPA has compared the 

likely air quality with a source having 

maximum allowable emissions under an 

appropriately set longer-term limit, as 

compared to the likely air quality with 

the source having maximum allowable 

emissions under the comparable 1-hour 

limit. In this comparison, in the 1-hour 

average limit scenario, the source is 

presumed at all times to emit at the 

critical emission level, and in the 

longer-term average limit scenario, the 

source is presumed occasionally to emit 

more than the critical emission value 

but on average, and presumably at most 

times, to emit well below the critical 

emission value. In an ‘‘average year,’’ 

compliance with the 1-hour limit is 

expected to result in three exceedance 

days (i.e., three days with hourly values 

above 75 ppb) and a fourth day with a 

maximum hourly value at 75 ppb. By 

comparison, with the source complying 

with a longer-term limit, it is possible 

that additional exceedances would 

occur that would not occur in the 1- 

hour limit scenario (if emissions exceed 

the critical emission value at times 

when meteorology is conducive to poor 

air quality). However, this comparison 

must also factor in the likelihood that 

exceedances that would be expected in 

the 1-hour limit scenario would not 

occur in the longer-term limit scenario. 

This result arises because the longerterm limit requires lower emissions 

most of the time (because the limit is set 

well below the critical emission value), 

so a source complying with an 

appropriately set longer-term limit is 

likely to have lower emissions at critical 

times than would be the case if the 

source were emitting as allowed with a 

1-hour limit. 

As a hypothetical example to 

illustrate these points, suppose a source 

always emits 1,000 pounds of SO2 per 

hour and results in air quality at the 

level of the NAAQS (i.e., results in a 

design value of 75 ppb). Suppose further 

that in an ‘‘average year,’’ these 

emissions cause the five highest 

maximum daily average 1-hour 

concentrations to be 100 ppb, 90 ppb, 80 

ppb, 75 ppb, and 70 ppb. Then suppose 

that the source becomes subject to a 30- 

day average emission limit of 700 

pounds per hour. It is theoretically 

possible for a source meeting this limit 

to have emissions that occasionally 

exceed 1,000 pounds per hour, but with 

a typical emission profile, emissions 

would much more commonly be 

between 600 and 800 pounds per hour. 

In this simplified example, assume a 

zero background concentration, which 

allows one to assume a linear 

relationship between emissions and air 

quality. (A nonzero background 

concentration would make the 

mathematics more difficult but would 

give similar results.) Air quality will 

depend on what emissions occur during 

critical hours, but suppose that 

emissions at the relevant times on these 

5 days are 800 pounds per hour, 1,100 

pounds per hour, 500 pounds per hour, 

900 pounds per hour, and 1,200 pounds 

per hour, respectively. (This is a 

conservative example because the 

average of these emissions, 900 pounds 

per hour, is well over the 30-day average 

emission limit.) These emissions would 

result in daily maximum 1-hour 

concentrations of 80 ppb, 99 ppb, 40 

ppb, 67.5 ppb, and 84 ppb. In this 

example, the fifth day would have an 

exceedance that would not otherwise 

have occurred, but the third and fourth 

days would not have exceedances that 

otherwise would have occurred. In this 

example, the fourth highest maximum 

daily concentration under the 30-day 

average would be 67.5 ppb. 

This simplified example illustrates 

the findings of a more complicated 

statistical analysis that EPA conducted 

using a range of scenarios using actual 

plant data. As described in appendix B 

of EPA’s April 2014 SO2 nonattainment 

planning guidance, EPA found that the 

requirement for lower average emissions 

is highly likely to yield better air quality 

than is required with a comparably 

stringent 1-hour limit. Based on 

analyses described in appendix B of our 

April 2014 guidance, EPA expects that 

an emission profile with maximum 

allowable emissions under an 

appropriately set comparably stringent 

30-day average limit is likely to have the 

net effect of having a lower number of 

exceedances and better air quality than 

an emission profile with maximum 

allowable emissions under a 1-hour 

emission limit at the critical emission 

value. This result provides a compelling 

policy rationale for allowing the use of 

a longer averaging period in appropriate 

circumstances where the facts indicate 

this result can be expected to occur. 

The question then becomes whether 

this approach—which is likely to 

produce a lower number of overall 

exceedances even though it may 

produce some unexpected exceedances 

above the critical emission value— 

meets the requirement in section 

110(a)(1) and 172(c)(1) and (6) for state 

implementation plans to ‘‘provide for 


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Federal Register / Vol. 82, No. 187 / Thursday, September 28, 2017 / Proposed Rules 45245 

2For example, if the critical emission value is 

1,000 pounds of SO2 per hour, and a suitable 

adjustment factor is determined to be 70 percent, 

the recommended longer-term average limit would 

be 700 pounds per hour. 

attainment’’ of the NAAQS. For SO2, as 

for other pollutants, it is generally 

impossible to design a nonattainment 

plan in the present that will guarantee 

that attainment will occur in the future. 

A variety of factors can cause a welldesigned attainment plan to fail and 

unexpectedly not result in attainment, 

for example if meteorology occurs that 

is more conducive to poor air quality 

than was anticipated in the plan. 

Therefore, in determining whether a 

plan meets the requirement to provide 

for attainment, EPA’s task is commonly 

to judge not whether the plan provides 

absolute certainty that attainment will 

in fact occur, but rather whether the 

plan provides an adequate level of 

confidence of prospective NAAQS 

attainment. From this perspective, in 

evaluating use of a 30-day average limit, 

EPA must weigh the likely net effect on 

air quality. Such an evaluation must 

consider the risk that occasions with 

meteorology conducive to high 

concentrations will have elevated 

emissions leading to exceedances that 

would not otherwise have occurred, and 

must also weigh the likelihood that the 

requirement for lower emissions on 

average will result in days not having 

exceedances that would have been 

expected with emissions at the critical 

emission value. Additional policy 

considerations, such as in this case the 

desirability of accommodating real 

world emissions variability without 

significant risk of violations, are also 

appropriate factors for EPA to weigh in 

judging whether a plan provides a 

reasonable degree of confidence that the 

plan will lead to attainment. Based on 

these considerations, especially given 

the high likelihood that a continuously 

enforceable limit averaged over as long 

as 30 days, determined in accordance 

with EPA’s guidance, will result in 

attainment, EPA believes as a general 

matter that such limits, if appropriately 

determined, can reasonably be 

considered to provide for attainment of 

the 2010 SO2 NAAQS. 

The April 2014 guidance offers 

specific recommendations for 

determining an appropriate longer-term 

average limit. The recommended 

method starts with determination of the 

1-hour emission limit that would 

provide for attainment (i.e., the critical 

emission value), and applies an 

adjustment factor to determine the 

(lower) level of the longer-term average 

emission limit that would be estimated 

to have a stringency comparable to the 

otherwise necessary 1-hour emission 

limit. This method uses a database of 

continuous emission data reflecting the 

type of control that the source will be 

using to comply with the SIP emission 

limits, which (if compliance requires 

new controls) may require use of an 

emission database from another source. 

The recommended method involves 

using these data to compute a complete 

set of emission averages, computed 

according to the averaging time and 

averaging procedures of the prospective 

emission limitation. In this 

recommended method, the ratio of the 

99th percentile among these longer-term 

averages to the 99th percentile of the 1- 

hour values represents an adjustment 

factor that may be multiplied by the 

candidate 1-hour emission limit to 

determine a longer-term average 

emission limit that may be considered 

comparably stringent.2 The guidance 

also addresses a variety of related 

topics, such as the potential utility of 

setting supplemental emission limits, 

such as mass-based limits, to reduce the 

likelihood and/or magnitude of elevated 

emission levels that might occur under 

the longer-term emission rate limit. 

Preferred air quality models for use in 

regulatory applications are described in 

appendix A of EPA’s Guideline on Air 

Quality Models. In 2005, EPA 

promulgated AERMOD as the Agency’s 

preferred near-field dispersion modeling 

for a wide range of regulatory 

applications addressing stationary 

sources (for example in estimating SO2

concentrations) in all types of terrain 

based on extensive developmental and 

performance evaluation. On December 

20, 2016, EPA revised the Guideline, 

which provided additional regulatory 

options and updated methods for 

dispersion modeling with AERMOD; the 

updates became effective on May 22, 

2017. Supplemental guidance on 

modeling for purposes of demonstrating 

attainment of the SO2 standard is 

provided in appendix A to the April 23, 

2014 SO2 nonattainment area SIP 

guidance document referenced above. 

Appendix A of the guidance provides 

extensive guidance on the modeling 

domain, source inputs, assorted types of 

meteorological data, and background 

concentrations. Consistency with the 

recommendations in this guidance is 

generally necessary for the attainment 

demonstration to offer adequately 

reliable assurance that the plan provides 

for attainment. 

As stated previously, attainment 

demonstrations for the 2010 1-hour 

primary SO2 NAAQS must demonstrate 

future attainment and maintenance of 

the NAAQS in the entire area 

designated as nonattainment (i.e., not 

just at the violating monitor) by using 

air quality dispersion modeling to show 

that the mix of sources and enforceable 

control measures and emission rates in 

an identified area will not lead to a 

violation of the SO2 NAAQS. For a 

short-term (e.g., 1-hour) standard, EPA 

believes that dispersion modeling using 

allowable emissions and addressing 

stationary sources in the affected area 

(and in some cases those sources located 

outside the nonattainment area which 

may affect attainment in the area) is 

technically appropriate, efficient, and 

effective in demonstrating attainment in 

nonattainment areas because it takes 

into consideration combinations of 

meteorological and emission source 

operating conditions that may 

contribute to peak ground-level 

concentrations of SO2. 

The meteorological data used in the 

analysis should generally be processed 

with the most recent version of 

AERMET. Estimated concentrations 

should include ambient background 

concentrations, should follow the form 

of the standard, and should be 

calculated as described in the August 

23, 2010 clarification memo on 

‘‘Applicability of Appendix W Modeling 

Guidance for the 1-hr SO2 National 

Ambient Air Quality Standard.’’ 

IV. Review of Modeled Attainment Plan 

The following discussion evaluates 

various features of the modeling that 

New Hampshire used in its attainment 

demonstration. 

A. Model Selection and Modeling 

Components 

New Hampshire’s attainment 

demonstration used EPA’s preferred 

model AERMOD (version 15181) with 

default options (e.g., without use of the 

ADJ_U* option) and rural dispersion 

coefficients for this application. The 

AERMOD modeling system contains the 

following components: 

—AERMOD: The dispersion model 

—AERMAP: The terrain processor for 

AERMOD 

—AERMET: The meteorological data 

processor for AERMOD 

—BPIP–PRIME: The building input 

processor 

—AERMINUTE: A pre-processor to 

AERMET incorporating 1-minute 

automated surface observation system 

(ASOS) wind data 

—AERSURFACE: The surface 

characteristics processor for AERMET 

—AERSCREEN: A screening version of 

AERMOD 

For any dispersion modeling exercise, 

the ‘‘urban’’ or ‘‘rural’’ determination of 


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a source is important in determining the 

boundary layer characteristics that affect 

the model’s prediction of downwind 

concentrations. For SO2 modeling, the 

urban/rural determination is important 

because AERMOD invokes a 4-hour 

half-life for urban SO2 sources. 

To investigate whether the rural 

determination was correct, EPA 

examined aerial imagery within 3 km of 

the facility and classified land use 

within the total area, as described in 

section 7.2.1.1 of the Guideline. Using 

this approach, EPA found that less than 

50 percent of the land use in the area 

reflected urban characteristics, and that 

therefore, consistent with the State’s 

selection, rural dispersion 

characteristics were most appropriate 

for use in this assessment. 

The State used AERMOD version 

15181, the most up-to-date version at 

the time the area was modeled, using all 

regulatory default options. AERMOD 

version 16216r has since become the 

regulatory model version. There were no 

updates from 15181 to 16216r that 

would significantly affect the 

concentrations predicted here. 

The ADJ_U* option, which adjusts the 

minimum surface roughness velocity 

under stable, low-wind speed 

conditions, was not invoked by the 

State. Not invoking ADJ_U*, as in the 

demonstration submitted by New 

Hampshire, may result in higher 

modeled concentrations; therefore, this 

element of the model option selection is 

conservative (i.e., unlikely to 

underpredict concentrations). 

EPA finds this selection appropriate 

because this model version using 

default options is sufficiently up to date, 

the rural option selection is in line with 

site characteristics, and the selection of 

default surface roughness velocity 

characteristics (i.e., no ADJ_U*) is not 

expected to underpredict 

concentrations. 

B. Area of Analysis 

New Hampshire accounted for SO2

impacts in the modeling domain, which 

extends in a 50 km radius around 

Merrimack Station and includes both 

locations within and outside of the 

nonattainment area, through the 

inclusion of measured background 

levels and explicitly modeled emission 

sources. The only source New 

Hampshire included explicitly in the 

modeling was Merrimack Station. In the 

narrative of the January 31, 2017 SIP 

submittal, New Hampshire indicated 

that other emitters of SO2 were 

accounted for in the background levels 

monitored within the nonattainment 

area. (The approach for developing the 

monitored background levels is 

described in detail in section IV.H, 

below.) In the submittal, New 

Hampshire also identified sources with 

annual emissions greater than 100 tons 

SO2 per year outside of the 

nonattainment area. Specifically, in the 

submission to EPA, New Hampshire 

identified Schiller Station and 

Newington Station, which are both 

located in the New Hampshire seacoast 

area approximately 55 km to the east 

southeast of Merrimack Station, as the 

principal nearby emitters of over 100 

tons SO2 annually. Schiller and 

Newington stations are each located 

about 30 km from the boundary of the 

nonattainment area. 

For the purpose of ensuring that no 

other sources of SO2 were 

inappropriately excluded in New 

Hampshire’s modeling, EPA reviewed 

its 2014 National Emissions Inventory 

(NEI), version 1 for sources within or 

nearby to the nonattainment area. 

During this review, EPA identified one 

additional source in the region that has 

emitted greater than 100 tons of SO2

annually, though not within the Central 

New Hampshire Nonattainment Area. 

The source, Monadnock Paper Mills Inc. 

(Monadnock Paper), a pulp and paper 

facility located in Bennington, New 

Hampshire approximately 40 km to the 

southwest of Merrimack Station and 24 

km from the closest portion of the 

nonattainment area, emitted 148 tons 

SO2 in 2014 according to the 2014 NEI. 

EPA examined whether Monadnock 

Paper might have an influence on the 

nonattainment area. The main criterion 

described in section 8.3 of the Guideline 

for establishing whether a secondary 

source is adequately represented by 

ambient monitoring data is whether that 

secondary source causes a significant 

concentration gradient in the vicinity of 

the primary source under consideration. 

In this context, secondary sources that 

do not cause a significant concentration 

gradient are typically considered to be 

adequately represented in the monitored 

ambient background. Based on the 

magnitude of emissions and distance 

relative to the nonattainment area, EPA 

believes it is unlikely that Monadnock 

Paper will cause a significant 

concentration gradient within the 

nonattainment area and has concluded 

that Monadnock Paper is adequately 

represented in the monitored ambient 

background. 

To examine the possible influence of 

other sources on the nonattainment 

area, EPA considered the most recent 

modeling assessment for Schiller and 

Newington stations provided by New 

Hampshire to EPA in February 2017 for 

purposes of SO2 designations. That 

modeling and EPA’s evaluation of it are 

described in detail in the New 

Hampshire technical support document 

for EPA’s intended designations for the 

2010 SO2 NAAQS, for which EPA sent 

letters to states on August 22, 2017. 

Based on this information, EPA found 

no significant concentration gradient 

due to emissions from Schiller Station 

or Newington Station within the 

nonattainment area and has concluded 

that both stations are adequately 

represented in the monitored ambient 

background. 

Additionally, EPA believes that the 

background levels reasonably account 

for other sources influencing air quality 

within the nonattainment area because 

data used to develop background levels 

include hours during which those 

sources may have impacted the 

monitors. 

Therefore, based on the reasoning 

provided in the preceding paragraphs, 

EPA concludes that the State 

appropriately accounted for these other 

sources through the inclusion of 

monitored background concentrations 

(see section IV.H below). 

C. Receptor Grid 

Within AERMOD, air quality 

concentration results are calculated at 

discrete locations identified by the user; 

these locations are called receptors. The 

receptor placement for the area of 

analysis selected by the State is a 

network of polar grids centered on 

Merrimack Station to a distance of 50 

km in all directions. Polar grid radii 

were spaced at 10 degree intervals. 

Receptors were placed every 20 meters 

along the perimeter of and excluded 

within the facility. Polar receptors along 

the radii were spaced as follows: 

—20-meter spacing to 200 meters; 

—50-meter spacing from 200 meters to 

500 meters; 

—100-meter spacing from 500 meters to 

2 km; 

—250-meter spacing from 2 km to 10 

km; 

—500-meter spacing from 10 km to 30 

km; and 

—1,000-meter spacing from 30 km to 50 

km. 

In addition to the 4,349 receptors 

included in the description above, the 

State included 2,308 additional 

receptors in dense Cartesian arrays with 

100-meter spatial resolution, over areas 

of expected maximum predicted 

concentrations based on preliminary 

modeling. Specifically, this was done in 

areas of complex terrain features at 

distances between 5 and 15 km of 

Merrimack Station. 

The receptor network contained a 

total of 6,657 receptors, covering a 


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circular area of 50 km in radius, 

including the entirety of the 

nonattainment area. EPA finds that the 

modeling domain and receptor network 

are sufficient to identify maximum 

impacts from Merrimack Station, and 

are therefore adequate for characterizing 

the nonattainment area. 

D. Meteorological Data 

New Hampshire used AERMOD’s 

meteorological data preprocessor 

AERMET (version 15181) with 2 years 

of surface and concurrent upper air 

meteorological data. The State relied on 

site-specific surface observations 

collected at Merrimack Station in Bow, 

New Hampshire during the 23-month 

period from January 1994 through 

November 1995 at five meteorological 

tower measurement levels and fifteen 

SODAR (Sound Detection and Ranging) 

levels. In addition, the State used 

surface observations from the National 

Weather Service (NWS) station at 

Concord Municipal Airport in Concord, 

New Hampshire (WBAN Station No. 

14745) in the following ways: (1) To 

supplement site-specific surface data 

with additional parameters (sky cover, 

ceiling height, and surface pressure) not 

available in the site-specific 

meteorological data, (2) to substitute for 

missing site-specific wind observations 

(51 hours of the 16,776 hours of the 23 

month period), and (3) to extend the 

meteorological dataset through 

December 1995 to develop a full 2-year 

analysis period. Concord Municipal 

Airport is approximately 7 km to the 

north-northwest of Merrimack Station. 

The State used coincident upper air 

observations from different NWS 

stations located in Portland, Maine 

(WBAN Station No. 14764) from January 

1, 1994 through September 21, 1994, 

and Gray, Maine (WBAN Station No. 

54762) from September 22, 1994 

through December 31, 1995. (The 

Portland station ceased its upper air 

observations on September 22, 1994, 

when the Gray station began its upper 

air observations.) The Portland station is 

around 110 km to the northeast of 

Merrimack and the Gray station is 

around 130 km to the northeast of 

Merrimack. 

New Hampshire also considered the 

use of more recent (2008–2012) NWS 

data collected at Concord Municipal 

Airport. The State cited two potential 

advantages of using this alternative 

dataset, mainly that it was significantly 

newer and included data derived from 

1-minute resolution observations using 

the AERMINUTE preprocessor to 

AERMET. New Hampshire weighed 

these considerations against the 

advantages of using the 1994–1995 sitespecific data, specifically: (1) The 

observation height for the site-specific 

data is closer in height to the stacks at 

Merrimack Station than the 8 meter 

collection height for the NWS data; (2) 

the site-specific wind direction data are 

more representative of the channeling 

effect within the Merrimack River valley 

in the location of Merrimack Station; 

and (3) use of the site-specific data 

would be consistent with previous 

modeling of Merrimack, which relied on 

the site-specific meteorology. 

EPA concurs with the choice of 

surface and upper air meteorological 

data inputs as being appropriately 

representative of site-specific 

meteorology. Specifically, EPA has 

judged the representativeness of the 

measured surface meteorological data 

according to the following four factors, 

as listed in section 8.4.1(b) to the 

Guideline: (1) The proximity of the 

meteorological monitoring site to the 

area under consideration, (2) the 

complexity of the terrain, (3) the 

exposure of the meteorological 

monitoring site, and (4) the period of 

time during which data are collected. 

Regarding proximity (factor 1), the sitespecific data is preferred over the more 

distant NWS data, though both data 

sources are sufficiently close to be 

appropriately representative of the site. 

Regarding the complexity of terrain 

(factor 2), both Concord and the sitespecific location show wind flow 

patterns with predominant northwest 

flow and secondary southeast flows, but 

the site-specific data show a more 

pronounced valley channeling effect 

with fewer hours with wind flow in 

other directions. In terms of exposure of 

the site, neither location appears to be 

exposed in a way that would have 

biased data collection (factor 3). Finally, 

regarding the data collection time 

period (factor 4), the more recent data at 

the NWS station would allow for use of 

1-minute resolution data for more 

accurate wind data inputs, and would 

be preferred for this factor. 

Notwithstanding the age of the onsite 

data, current land-use is comparable to 

historical land-use, so that the historic 

meteorological data are sufficiently 

representative of current conditions. In 

summary, based on the four factors 

described above, despite the availability 

of recent nearby NWS data, the analysis 

suggests that the 1994–1995 site-specific 

data augmented with NWS data are 

more representative of conditions 

pertinent to releases at Merrimack 

Station. The 23 months of site-specific 

data supplemented with 1 additional 

month of NWS data represent an 

appropriate study period, consistent 

with EPA guidance contained in section 

8.4.2(e) of the Guideline, which states 

that at least 1 year of site-specific 

meteorological data are required to 

ensure that worst-case meteorological 

conditions are adequately represented 

in the model results. The upper air 

stations selected for the analysis are the 

closest sites and are suitably 

representative of the upper air in the 

Central New Hampshire Nonattainment 

Area, and are therefore most appropriate 

for developing upper air profiles for the 

State’s modeling analysis. 

The State used AERSURFACE version 

13016 using land cover data from the 

1992 National Land Cover Dataset 

(NLCD) for both surface data collection 

locations to estimate the surface 

characteristics (albedo, Bowen ratio, and 

surface roughness length) of the area of 

analysis. The State estimated surface 

roughness length values for 12 spatial 

sectors out to the recommended radius 

of 1 km at a monthly temporal 

resolution for average surface moisture 

conditions. EPA concurs with New 

Hampshire’s approach to developing 

relevant surface characteristics for use 

in processing meteorological data for 

this area. 

E. Source Characterization 

EPA also reviewed the State’s source 

characterization in its modeling 

assessment, including source types, use 

of accurate stack parameters, and 

inclusion of building dimensions for 

building downwash. The State’s source 

characterization in its modeling 

demonstration was consistent with the 

recommendations included in the 

Guideline. The source used actual stack 

height (445 feet), which EPA 

determined to be good engineering 

practice (GEP) height using BPIP– 

PRIME. The State also adequately 

characterized the source’s building 

layout and location, as well as the stack 

parameters, e.g., exit temperature, exit 

velocity, location, and diameter. EPA 

verified the position of buildings and 

stacks using aerial imagery and relevant 

stack parameters based on permit 

conditions. 

F. Emissions Data 

New Hampshire included maximum 

allowable 1-hour emissions from 

Merrimack Station in its modeled 

attainment demonstration for the 

Central New Hampshire Nonattainment 

Area. The State indicated that SO2 air 

quality in the area is almost entirely 

characterized by emissions from the two 

primary boilers at Merrimack Station, 

and this informed the State’s decision to 

only explicitly model SO2 emissions 

from Merrimack Station. Additional 


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3The March 1, 2011 EPA memorandum from 

Tyler Fox to EPA Regional Air Division Directors 

entitled ‘‘Additional Clarification Regarding 

Application of Appendix W Modeling Guidance for 

the 1-hour NO2 National Ambient Air Quality 

Standard,’’ which also includes information 

relevant to modeling for SO2, addresses treatment 

of intermittent sources. This guidance indicates that 

air permitting authorities have discretion to exclude 

certain types of intermittent emissions for modeling 

the 1-hour NAAQS on a case-specific basis. 

units (i.e., two peak combustion 

turbines, an emergency generator, an 

emergency boiler, and a fire pump) at 

Merrimack Station operate infrequently 

and were treated as intermittent sources; 

therefore, they were excluded from the 

modeling.3 The State provided 

historical (2011–2014) counts of hours 

of operation for these units to bolster its 

contention that these units do not 

contribute to the annual distribution of 

daily maximum 1-hour concentrations. 

Specifically, during the 2011–2014 

period, the two turbines were operated 

during an average of 40 and 45 hours 

per year, the emergency generator 

during an average of 17 hours per year, 

the emergency boiler during an average 

of 43 hours per year, and the fire pump 

during an average of 3 hours per year. 

The maximum annual usage of any of 

these pieces of equipment during that 

time was 114 hours for combustion 

turbine 1 in 2014. The emergency 

generator is limited through section 

Env-A 1311.02(a) of New Hampshire’s 

SIP-approved air pollution control 

regulations, to a maximum of 500 hours 

of operation during any consecutive 12- 

month period. The fire pump is limited 

to a maximum of 100 hours for 

maintenance and testing during any 

consecutive 12-month period because it 

is subject to EPA’s New Source 

Performance Standards for stationary 

internal combustion engines, 

specifically 40 CFR 60.4211(e). These 

utilization levels and patterns are 

consistent with EPA’s assessment of 

intermittent emissions based on the 

March 1, 2011 EPA guidance. EPA 

believes that this treatment is 

appropriate for those units in this area. 

New Hampshire provided attainment 

modeling used to support its 

establishment of emission rates for 

Merrimack Station. In establishing the 

emission limits, the State followed 

EPA’s April 2014 guidance by using 

modeling to develop a critical emission 

value and adjustment factor to establish 

a longer term limit for Merrimack. The 

State modeled three ‘‘normal operating 

scenarios,’’ comprised of one scenario 

with maximum operation of both utility 

boilers (scenario 1), and two other 

scenarios with maximum operation of 

each boiler individually (scenarios 2 

and 3, respectively). In 2011, New 

Hampshire issued a permit (TP–0008) 

for Merrimack Station that contained, 

among other things, SO2 emission limits 

associated with a flue gas 

desulfurization (FGD) system. The FGD 

was required to be installed at 

Merrimack Station by the New 

Hampshire legislature. See New 

Hampshire Revised Statutes Annotated 

(RSA) 125–O:11. EPA approved the SO2- 

related source-specific requirements of 

that permit into the New Hampshire SIP 

as part of the State’s regional haze SIP 

submittal. See 77 FR 50602 (August 22, 

2012). In September 2016, New 

Hampshire issued a second permit (TP– 

0189) for Merrimack Station, which 

included SO2 emission limits 

specifically designed to ensure 

compliance with the SO2 NAAQS. The 

emission limits included in TP–0189, 

and which New Hampshire has 

proposed for inclusion in the State’s 

SIP, apply at all times. The State’s 

modeling established a critical emission 

value of 2,544 pounds (lb) SO2 per hour 

for scenario 1, which the State 

concluded is comparably stringent to a 

7-boiler operating day rolling average 

limit of 0.39 lb SO2 per million British 

thermal units (MMBtu). The 7-boiler 

operating day rolling average emissions 

limits that would be comparably 

stringent to the 1-hour critical emission 

value under scenarios 2 and 3 would be 

0.92 and 0.47 lb SO2/MMBtu, 

respectively. Because scenario 1 was the 

basis for establishing this limit, and the 

limit (0.39 lb/MMBtu) is more stringent 

than the limits that would have been 

established for either scenario 2 or 3 

(0.92 and 0.47 lb/MMBtu, respectively), 

using emissions from scenario 1 as the 

basis of the modeling analysis is 

appropriate. See section IV.G.2 below 

for further details on the emissions in 

the State’s attainment modeling, 

including discussion of the State’s 

conclusion of comparable stringency 

with the critical emission value. 

In summary, EPA concurs with the 

State’s selection in its attainment 

demonstration modeling of emissions 

from utility boilers at Merrimack 

Station, and exclusion of additional 

emission sources at Merrimack due to 

their intermittent operation. 

G. Emission Limits 

An important prerequisite for 

approval of a nonattainment plan is that 

the emission limits that provide for 

attainment be quantifiable, fully 

enforceable, replicable, and 

accountable. See General Preamble at 

13567–68. The limits that New 

Hampshire’s plan relies on for 

Merrimack Station are expressed as 7- 

boiler operating day rolling average 

limits, where a boiler operating day is 

defined as a 24-hour period that begins 

at midnight and ends the following 

midnight during which any fuel is 

combusted at any time in the boiler; it 

is not necessary for the fuel to be 

combusted for the entire 24-hour period. 

Therefore, part of the review of New 

Hampshire’s nonattainment plan must 

address the use of these limits, both 

with respect to the general suitability of 

using such limits for this purpose and 

with respect to whether the particular 

limits included in the plan have been 

suitably demonstrated to provide for 

attainment. The first subsection that 

follows addresses the enforceability of 

the limits in the plan, and the second 

subsection that follows addresses in 

particular the 7-boiler operating day 

average limits. 

1. Enforceability 

On September 1, 2016, New 

Hampshire issued a permit, TP–0189, to 

Public Service of New Hampshire d/b/ 

a Eversource Energy for Merrimack 

Station. The permit became effective 

and enforceable upon issuance, and was 

issued pursuant to RSA 125–C:11. These 

requirements are more stringent than 

the applicable measures for the facility, 

which require 90% reduction for both 

MK1 and MK2, as incorporated into the 

SIP by reference to Table 4, Items 6 and 

8 of TP–0008. EPA considers the 30- 

boiler operating day limits included in 

TP–0189 (specifically, Table 4, Item 2) 

to supersede the conditions specified in 

Table 4, Items 6 and 8 of TP–0008. 

Monitoring, testing, and 

recordkeeping requirements related to 

all of the permit’s SO2 emission limits 

are clearly described in the permit and 

ensure that the limits are quantifiable, 

fully enforceable, and replicable. The 

accountability of the limits is 

established through the State’s inclusion 

of the permit limits in its nonattainment 

plan, and its modeling demonstration 

using the 1-hour emission levels that are 

comparably stringent to the permit 

limits. In accordance with EPA policy, 

the 7-boiler operating day average limit 

for Merrimack Station is set at a lower 

level than the critical emission value 

used in the attainment demonstration; 

the relationship between these two 

values is discussed in more detail in the 

following section. 

2. Longer-Term Average Limits 

New Hampshire developed a critical 

emission value for each of the three 

normal operating scenarios (see section 

IV.F above) using a target concentration 

threshold of 183.2 micrograms per cubic 

meter (mg/m3) by subtracting a 

background value of 12.8 mg/m3, the 


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4Using a numerical conversion factor of 2.619 mg/ 

m3 per ppb, the 2010 SO2 NAAQS of 75 ppb is 

equivalent to 196.4 mg/m3. The state rounded 196.4 

mg/m3 down to a more protective level of 196 mg/ 

m3. EPA is using the lower value in this case 

because it is consistent with the State’s analysis and 

is also protective of the NAAQS. 

highest hour-by-season background 

value (see section IV.H below), from 196 

mg/m3, which is equivalent to the level 

of the NAAQS of 75 ppb.4 The State 

then divided the target concentration 

threshold by the maximum predicted 

99th percentile concentration using a 

unit emission rate (i.e., 1 lb/hr) for each 

normal operating scenario to establish 

the critical emission value for each 

scenario (e.g., 2,544 lb/hr, equivalent to 

a limit of 0.54 lb/MMBtu at full 

operating load, for scenario 1). 

Using hourly emission data provided 

by EPA’s Air Markets Program Data 

database for Merrimack Station for the 

period between July 4, 2013 and March 

30, 2015 (i.e., since the FGD system 

became operational), the State derived 

adjustment factors for longer-term 

averaging periods for each scenario. 

Because the dataset includes only data 

from Merrimack Station using the 

control technology, it is appropriate for 

use in developing adjustment factors. 

Prior to deriving the adjustment factors, 

the State removed erroneous data points 

from the dataset based on information 

provided by the facility. The adjustment 

factors were calculated as the ratio of 

the 99th percentile of mass emissions 

for the longer-term period to the 99th 

percentile hourly mass emissions. For 

the rolling 7-day averaging period, the 

adjustment factor was 0.73 for each of 

the three scenarios. That is, the 7-day 

mass emission rate limit would need to 

be 0.73 times (or 27% lower than) the 

critical emission value to have 

comparable stringency as a 1-hour rate 

limit. The 7-day adjustment factor of 

0.73 for Merrimack Station is similar to 

0.71, EPA’s average 30-day adjustment 

factor for sources with wet scrubbers 

(derived from a database of 210 sources) 

as listed in appendix D of the April 

2014 guidance. The State then derived 

emission limits for each scenario on an 

emission per heat-input basis, and 

selected the lowest level for the 7-day 

averaging period of 0.39 lb/MMBtu. 

Based on a review of the State’s 

submittal, EPA believes that the 7-boiler 

operating day average limit for 

Merrimack Station provides a suitable 

alternative to establishing a 1-hour 

average emission limit for this source. 

The State has used a suitable database 

in an appropriate manner and has 

thereby applied an appropriate 

adjustment, yielding an emission limit 

that has comparable stringency to the 1- 

hour average limit that the State 

determined would otherwise have been 

necessary to provide for attainment. 

While the 7-boiler operating day average 

limit allows occasions in which 

emissions may be higher than the level 

that would be allowed with the 1-hour 

limit, the State’s limit compensates by 

requiring average emissions to be lower 

than the level that would otherwise 

have been required by a 1-hour average 

limit. For the reasons described above 

and explained in more detail in EPA’s 

April 2014 guidance for SO2

nonattainment plans, EPA finds that 

appropriately set longer-term average 

limits provide a reasonable basis by 

which nonattainment plans may 

provide for attainment. Based on our 

review of this general information as 

well as the particular information in 

New Hampshire’s plan, EPA finds that 

the 7-boiler operating day average limit 

for Merrimack Station will provide for 

attainment of the SO2 NAAQS. 

In the April 2014 guidance for SO2, 

EPA also described possible 

supplemental limits on the frequency 

and/or magnitude of elevated emissions 

to strengthen the justification for the use 

of longer-term average limits to protect 

against NAAQS violations. One option 

provided in the guidance regarding this 

topic is the use of relatively shorter 

averaging times, which provide less 

allowance of emission spikes than 

would longer averaging times, i.e., the 

30-day averaging time. In this instance, 

the emission limit for Merrimack 

Station is on a 7-boiler operating day 

average basis and the limit applies at all 

times. Furthermore, the adjustment 

factor used to derive the limit is similar 

to 0.71, EPA’s average 30-day 

adjustment factor for sources with wet 

scrubbers as listed in appendix D of the 

April 2014 guidance, meaning that the 

factor used to adjust the emission limit 

downward is more pronounced for a 7- 

day period than would typically be 

expected. Based on these 

considerations, EPA believes that the 7- 

boiler operating day limits are 

sufficiently protective of the NAAQS 

without application of an additional, 

supplemental limit. 

H. Background Concentrations 

To develop background 

concentrations for the nonattainment 

area, the State of New Hampshire relied 

on 2012–2014 data from two monitors 

within the nonattainment area: The 

Pembroke monitor, Air Quality System 

(AQS) number 33–013–1006, and the 

Concord monitor, AQS number 33–013– 

1007. The Pembroke monitor is located 

on Pleasant Street in Pembroke, New 

Hampshire, about 1.3 km to the 

southeast of Merrimack Station, and the 

Concord monitor is located at Hazen 

Drive in Concord, New Hampshire, 

about 9.4 km to the north-northwest of 

Merrimack Station. Each of these 

monitors was sited to record 

neighborhood scale exposure levels 

rather than regional background levels; 

there are currently no regional 

background monitors in the Central 

New Hampshire Nonattainment Area. 

Per section 8.3.1.a of the Guideline, 

background air quality should not 

include the ambient impacts of the 

source under consideration. Both the 

Pembroke and Concord monitors reflect 

impacts attributable to Merrimack 

Station. One solution to develop 

background concentrations from 

monitoring data around an isolated 

source, as described in section 8.3.2.c.i 

of the Guidance, is to exclude monitor 

measurements collected when wind is 

from a 90° sector centered on the source. 

Due to the low wind speeds and 

swirling winds characteristic of 

Merrimack Station’s river valley 

location, emissions from the source may 

contribute to the monitors even when 

the wind direction is outside of the 90° 

sector. Therefore, the State determined 

that the 90° exclusion sector approach 

was not appropriate for this application, 

and selected an alternative approach to 

develop background levels. Specifically, 

the State compiled an ambient 

concentration database using the lower 

observed value for the two monitors’ 

hourly values as representing regional 

background levels. This approach 

accounts for area and mobile sources 

and more distant sources that were not 

modeled explicitly but affect SO2 levels 

in the nonattainment area without also 

double-counting impacts from 

Merrimack Station, which was modeled 

explicitly. Using this approach, EPA 

finds the State’s treatment of SO2

background levels to be suitable for the 

modeled attainment demonstration. 

I. Summary of Results 

The modeling analysis upon which 

the State relied in establishing a critical 

emission value for setting emission 

limits for Merrimack Station results in 

concentrations of no greater than 196.0 

mg/m3, which is below the level of the 

1-hour primary SO2 NAAQS of 196.4 

mg/m3. EPA agrees with the State that 

these results indicate that emissions at 

the critical emission value for 

Merrimack Station provide for 

attainment of the 1-hour SO2 NAAQS. 


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45250 Federal Register / Vol. 82, No. 187 / Thursday, September 28, 2017 / Proposed Rules 

V. Review of Other Plan Requirements 

A. Emissions Inventory 

The emissions inventory and source 

emission rate data for an area serve as 

the foundation for air quality modeling 

and other analyses that enable states to: 

(1) Estimate the degree to which 

different sources within a 

nonattainment area contribute to 

violations within the affected area; and 

(2) assess the expected improvement in 

air quality within the nonattainment 

area due to the adoption and 

implementation of control measures. As 

noted above, the State must develop and 

submit to EPA a comprehensive, 

accurate, and current inventory of actual 

emissions from all sources of SO2

emissions in each nonattainment area, 

as well as any sources located outside 

the nonattainment area which may 

affect attainment in the area. See CAA 

section 172(c)(3). 

In its plan, New Hampshire included 

a current emissions inventory for the 

nonattainment area and also for the 

three-county area of Hillsborough, 

Merrimack, and Rockingham Counties 

based on the 2011–2015 period. The 

State principally relied on 2014 as the 

most complete and representative 

record of annual SO2 emissions because 

it coincided with EPA’s National 

Emissions Inventory (NEI), which 

includes a comprehensive inventory of 

all source types. The State allocated 

2014 NEI version 1 emissions from the 

portion of each county within the 

nonattainment area using city- and 

town-level population (for area and nonroad mobile sources) and vehicle miles 

traveled (VMT; for on-road mobile 

sources) statistics. The State included 

emissions from point sources (e.g., 

Merrimack Station) to the area based on 

location. The State calculated emissions 

for the area from some types of sources 

based on county-level emissions. A 

summary of the State’s emissions 

inventories for 2011, 2014, and 2018 are 

presented in Table 1. Based on the 

State’s inventory, of the 5,471 tons SO2

emitted in 2014 within the three county 

area, 1,480 tons were emitted within the 

nonattainment area. Merrimack Station 

emitted 1,044 tons SO2 in 2014. These 

emissions levels are much lower than 

historical emissions levels; for example, 

in 2011, Merrimack Station emitted 

22,420 tons SO2. 

TABLE 1—SUMMARY OF NEW HAMPSHIRE’S INVENTORY OF ACTUAL SO2 EMISSIONS FOR THE CENTRAL NEW HAMPSHIRE

AREA

Year 

Hillsborough, 

Merrimack, and 

Rockingham 

Counties 

(tons) 

Central New 

Hampshire nonattainment area 

(tons) 

Merrimack 

Station 

(tons) 

2011 ................................................................................................................................. 24,934 22,398 22,420 

2014 ................................................................................................................................. 5,471 1,480 1,044 

2018 (projected) ............................................................................................................... 6,966 2,473 1,927 

New Hampshire also developed a 

projected emission inventory for the 

2018 attainment year. The emissions 

projection indicates 1,927 tons of SO2

from Merrimack Station and a total of 

2,473 tons of SO2 within the 

nonattainment area; however, these 

projections rely on a 90% reduction in 

SO2 emissions from Merrimack Station, 

which is less stringent than the at least 

93.4% reduction incorporated into the 

permit New Hampshire issued for 

Merrimack Station on September 1, 

2016, TP–0189. 

EPA agrees that the State’s emissions 

inventories are appropriate because they 

rely on well-established and vetted 

estimates of emissions for the current 

period and attainment year, 

respectively. 

B. RACM/RACT 

CAA section 172(c)(1) requires that 

each attainment plan provide for the 

implementation of all reasonably 

available control measures (RACM) as 

expeditiously as practicable (including 

such reductions in emissions from 

existing sources in the area as may be 

obtained through the adoption, at a 

minimum, of reasonably available 

control technology (RACT)) and shall 

provide for attainment of the NAAQS. 

EPA interprets RACM, including RACT, 

under section 172, as measures that a 

state determines to be reasonably 

available and which contribute to 

attainment as expeditiously as 

practicable for existing sources in the 

area. 

In its January 31, 2017 SIP submittal, 

New Hampshire identified the 

operational and SO2 emission limits 

contained in Merrimack Station’s 

permit, TP–0189, as meeting RACM/ 

RACT. New Hampshire’s plan for 

attaining the 1-hour SO2 NAAQS in the 

Central New Hampshire Nonattainment 

Area is based on the operational and 

emission limitations contained in 

Merrimack Station’s permit. 

Specifically, Merrimack Station’s permit 

limits SO2 emissions from the MK1 and 

MK2 boilers at Merrimack Station to 

0.39 lb/MMBtu on a 7-boiler operating 

day rolling average (achieved through 

operation of the FGD), which the State 

demonstrated was comparably stringent 

to the critical emission value that 

provides for attainment of the NAAQS, 

as described in section IV.G.2 above. 

New Hampshire’s nonattainment plan 

includes the SO2 control measures 

required by the permit, which was 

effective immediately upon issuance on 

September 1, 2016. New Hampshire has 

determined that these measures suffice 

to provide for timely attainment, and 

plans to incorporate relevant conditions 

contained in TP–0189 into Merrimack’s 

title V operating permit (TV–0055). 

The air modeling analysis submitted 

to EPA during the development of the 

SO2 limits in TP–0189 confirms that 

these limits are protective of the 

NAAQS, as described in section IV. 

Because the modeling demonstrates 

attainment using emission limits 

contained in Merrimack Station’s 

permit, TP–0189, the State determined 

that controls for SO2 emissions at 

Merrimack Station are appropriate in 

the Central New Hampshire Area for 

purposes of attaining the 2010 SO2

NAAQS. Accordingly, New Hampshire 

only completed a RACM/RACT analysis 

for Merrimack Station because the air 

quality modeling showed that the SO2

emission reductions required by TP– 

0189 will be sufficient to ensure that the 

nonattainment area achieves attainment 

with the SO2 NAAQS. EPA believes that 

New Hampshire’s approach is 

consistent with EPA’s April 2014 

guidance, which indicates that ‘‘[a]ir 

agencies should consider all RACM/ 

RACT that can be implemented in light 

of the attainment needs for the affected 

area(s).’’ 

The Central New Hampshire Area is 

currently showing an attaining design 

value for 2014–2016, and has been since 


jstallworth on DSKBBY8HB2PROD with PROPOSALS
Federal Register / Vol. 82, No. 187 / Thursday, September 28, 2017 / Proposed Rules 45251 

the 2012–2014 period, which means 

that attainment of the NAAQS is as 

expeditious as practicable. 

Based on New Hampshire’s modeling 

demonstration, which accounted for the 

SO2 emission limits contained in 

Merrimack Station’s permit, TP–0189, 

the Central New Hampshire Area is 

projected to attain the 2010 SO2 NAAQS 

by the 2018 attainment date. Because 

the area is currently attaining the 2010 

SO2 NAAQS, EPA proposes to find that 

the control strategy will ensure 

attainment of the NAAQS by the 

required attainment date. 

The State’s plan also includes a 

broader discussion of the SO2 control 

strategy beyond Merrimack Station’s 

permit, TP–0189. Merrimack Station is 

also subject to requirements of the 

Mercury and Air Toxics Standards 

(MATS), which promotes reductions at 

subject facilities of certain hazardous air 

pollutants, including hydrochloric acid; 

such reductions are achieved at 

Merrimack Station through the 

operation of the FGD system, which 

concurrently reduces emissions of SO2. 

New Hampshire also notes in its 

nonattainment plan the anticipated 73% 

reduction in SO2 emissions among 

upwind states subject to EPA’s Cross 

State Air Pollution Rule (CSAPR), 

which will lessen the contribution of 

sources from other states into the 

nonattainment area in future years. New 

Hampshire also described emissions 

reductions at Schiller Station as part of 

statewide efforts to reduce SO2, as well 

as other state rules. 

EPA concurs with New Hampshire’s 

approach and analysis, and proposes to 

conclude that the State has satisfied the 

requirement in section 172(c)(1) to 

adopt and submit all RACM as needed 

to attain the SO2 NAAQS as 

expeditiously as practicable. 

C. New Source Review (NSR) 

EPA last approved New Hampshire’s 

Env-A 618 nonattainment new source 

review rules on May 25, 2017 (82 FR 

24057). These rules provide for 

appropriate new source review for SO2

sources undergoing construction or 

major modification in the Central New 

Hampshire Nonattainment Area without 

need for modification of the approved 

rules. Therefore, EPA concludes that 

this requirement has already been met 

for this area. 

D. Reasonable Further Progress (RFP) 

New Hampshire concluded that the 

appropriate control measures were 

implemented as expeditiously as 

practicable in order to ensure 

attainment of the standard by the 

applicable attainment date. Specifically, 

the State implemented its main control 

strategy, i.e., establishment of federally 

enforceable SO2 emissions limits and 

operational conditions in TP–0189 for 

Merrimack Station in September 2016. 

New Hampshire concluded that this 

plan therefore provides for RFP in 

accordance with the approach to RFP 

described in EPA’s guidance. EPA 

concurs and proposes to conclude that 

the plan provides for RFP. 

E. Contingency Measures 

As discussed in our guidance, Section 

172(c)(9) of the CAA defines 

contingency measures as such measures 

in a SIP that are to be implemented in 

the event that an area fails to make RFP, 

or fails to attain the NAAQS, by the 

applicable attainment date. Contingency 

measures are to become effective 

without further action by the state or 

EPA, where the area has failed to (1) 

achieve RFP or (2) attain the NAAQS by 

the statutory attainment date for the 

affected area. These control measures 

are to consist of other available control 

measures that are not included in the 

control strategy for the nonattainment 

area SIP. EPA guidance describes 

special features of SO2 planning that 

influence the suitability of alternative 

means of addressing the requirement in 

section 172(c)(9) for contingency 

measures for SO2. Because SO2 control 

measures are by definition based on 

what is directly and quantifiably 

necessary emissions controls, any 

violations of the NAAQS are likely 

related to source violations of a source’s 

permit terms. Therefore, an appropriate 

means of satisfying this requirement for 

SO2 is for the state to have a 

comprehensive enforcement program 

that identifies sources of violations of 

the SO2 NAAQS and to undertake an 

aggressive follow-up for compliance and 

enforcement. 

For its contingency program, New 

Hampshire proposed to continue to 

operate a comprehensive program to 

identify sources of violations of the SO2

NAAQS and undertake aggressive 

compliance and enforcement actions, 

including expedited procedures for 

establishing consent agreements 

pending the adoption of the revised SIP. 

New Hampshire’s program for 

enforcement of SIP measures for the 

2010 SO2 NAAQS was approved by EPA 

on June 15, 2016. See 81 FR 44542. As 

EPA stated in its April 2014 guidance, 

EPA believes that this approach 

continues to be a valid approach for the 

implementation of contingency 

measures to address the 2010 SO2

NAAQS. 

Based on the contingency measures 

identified by the State in its plan 

submittal, EPA believes that New 

Hampshire’s plan provides for satisfying 

the contingency measure requirement. 

EPA concurs and proposes to approve 

New Hampshire’s plan for meeting the 

contingency measure requirement in 

this manner. 

VI. Additional Elements of New 

Hampshire’s Submittal 

A. Conformity 

The State addresses general 

conformity and transportation 

conformity requirements as they apply 

to the nonattainment area. Generally, as 

set forth in section 176(c) of the Clean 

Air Act, conformity requires that actions 

by federal agencies do not cause new air 

quality violations, worsen existing 

violations, or delay timely attainment of 

the relevant NAAQS. General 

conformity applies to federal actions, 

other than certain highway and 

transportation projects, if the action 

takes place in a nonattainment area or 

maintenance area (i.e., an area which 

submitted a maintenance plan that 

meets the requirements of section 175A 

of the CAA and has been redesignated 

to attainment) for ozone, particulate 

matter, nitrogen dioxide, carbon 

monoxide, lead, or SO2. EPA’s General 

Conformity Rule (40 CFR 93.150 to 

93.165) establishes the criteria and 

procedures for determining if a federal 

action conforms to the SIP. With respect 

to the 2010 SO2 NAAQS, federal 

agencies are expected to continue to 

estimate emissions for conformity 

analyses in the same manner as they 

estimated emissions for conformity 

analyses under the previous NAAQS for 

SO2. EPA’s General Conformity Rule 

includes the basic requirement that a 

federal agency’s general conformity 

analysis be based on the latest and most 

accurate emission estimation techniques 

available (40 CFR 93.159(b)). When 

updated and improved emissions 

estimation techniques become available, 

EPA expects the federal agency to use 

these techniques. New Hampshire 

addresses general conformity under SIPapproved state rule Env-A 1500. 

Federal Highway and Federal Transit 

Administration projects are subject to 

transportation conformity rather than 

general conformity requirements, with 

some exceptions. New Hampshire 

asserts in its plan that due to minimal 

impact on SO2 from combustion of 

gasoline and diesel fuels, transportation 

conformity rules do not generally apply 

to SO2 unless the EPA Regional 

Administrator or the state air director 

finds that its transportation-related SO2

emissions are a significant contributor 

to fine particulate matter as a precursor. 


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45252 Federal Register / Vol. 82, No. 187 / Thursday, September 28, 2017 / Proposed Rules 

This reasoning is consistent with EPA’s 

April 2014 guidance and EPA proposes 

to conclude that New Hampshire’s plan 

meets our guidance and rule 

requirements with regard to general and 

transportation conformity. 

B. Changes in Allowable Emissions 

The State quantified the changes in 

allowable emissions expected to result 

from implementation of its 

nonattainment area plan. To do so, the 

State compared allowable annual 

emissions at Merrimack Station prior to 

installation of the FGD control system 

with those after the system was 

operational and with those with the 

conditions of TP–0189 in place (i.e., 

allowable emissions under the plan). 

Prior to the effective date of TP–0189, 

under the conditions of TP–0008 (see 77 

FR 50602), Merrimack Station was 

permitted to operate the MK1 boiler 

through the bypass stack (i.e., now the 

emergency stack) for no more than 840 

hours during any consecutive 12-month 

period and thereby bypass SO2 controls; 

the MK2 boiler is unable to operate 

through the bypass stack. The State 

quantified emissions from these boilers 

which were allowed prior to installation 

of the FGD and the effective date of TP– 

0008. Then, the State quantified 

emissions from the MK1 and MK2 

boilers under the provisions of TP–0008 

(i.e., using a 90% emissions reduction). 

Finally, the State quantified emissions 

for MK1 and MK2 allowed under the 

provisions of TP–0189, i.e., assuming an 

average of 0.39 lb/MMBtu. A summary 

of these allowable emissions is 

presented in Table 2. According to the 

plan, allowable annual SO2 emissions 

prior to the FGD installation (and the 

conditions of TP–0008) were 82,537 

tons, compared to 8,254 tons under the 

permit conditions of TP–0008, and 

8,047 tons under the nonattainment 

plan (namely the SO2 emissions limit 

for NAAQS compliance included in TP– 

0189). That is, the State expects 

implementation of the plan to allow 207 

tons fewer than prior to plan 

implementation, and 74,490 tons fewer 

than prior to installation and operation 

of the FGD. 

TABLE 2—SUMMARY OF ANNUAL ALLOWABLE SO2 EMISSIONS FOR THE MK1 AND MK2 BOILERS AT MERRIMACK STATION

Total allowable 

emissions 

Difference in 

allowable 

emissions 

from prior to 

TP–0008 

(tons) 

Difference in 

allowable 

emissions 

from prior to 

TP–0189 

(tons) 

Prior to TP–0008 ......................................................................................................................... 82,537 

With TP–0008 .............................................................................................................................. 8,254 a¥74,283 

Nonattainment Area Plan (With TP–0189) .................................................................................. 8,047 a¥74,489 a b¥206 

a Reported negative emissions values for differences indicate emission reductions. 

b New Hampshire reported a difference of 206 tons compared with the numerical difference of 207 tons between the reported total allowable 

emissions. This slight difference can be attributed to rounding. 

C. Air Quality Trends 

New Hampshire also included trends 

in ambient monitoring data for the 

nonattainment area. In its 

nonattainment plan, the State shows 

that ambient concentrations in the area 

have dropped markedly since 2011, 

when Merrimack Station began 

operation of its FGD system under the 

SIP-approved conditions of TP–0008, 

and are now below 75 ppb, the level of 

the NAAQS. The monitored design 

value for the Pembroke monitor (AQS 

number 33–013–1006), consistently the 

highest in the area, was 23 ppb for 2012 

to 2014, and 20 ppb for both 2013 to 

2015 and 2014 to 2016. 

D. Compliance With Section 110(a)(2) of 

the CAA 

Section 172(c)(7) of the CAA requires 

nonattainment SIPs to meet the 

applicable provisions of section 

110(a)(2) of the CAA. While the 

provisions of 110(a)(2) address various 

topics, EPA’s past determinations 

suggest that only the section 110(a)(2) 

criteria linked with a particular area’s 

designation and classification are 

relevant to section 172(c)(7). This 

nonattainment SIP submittal satisfies all 

applicable criteria of section 110(a)(2) of 

the CAA, as evidenced by the State’s 

nonattainment new source review 

program which addresses 110(a)(2)(I), 

the included control strategy, and the 

associated emissions limits which are 

relevant to 110(a)(2)(A). In addition, 

EPA approved the State’s SO2

infrastructure SIP on May 25, 2017 (82 

FR 24057). EPA will take action in a 

separate rulemaking on the remaining 

portion of the State’s infrastructure SIP, 

the so-called SO2 ‘‘good neighbor’’ or 

‘‘interstate transport’’ SIP to satisfy 

section 110(a)(2)(D)(i)(I) of the CAA. 

EPA is proposing to conclude that the 

State has meet the requirements of 

172(c)(7) of the CAA. 

E. Equivalency Techniques 

Section 172(c)(8) of the CAA states 

that upon application by any state, the 

Administrator may allow the use of 

equivalent modeling, emission 

inventory, and planning procedures, 

unless the Administrator determines 

that the proposed techniques are, in the 

aggregate, less effective than the 

methods specified by the Administrator. 

The State’s nonattainment SIP 

indicates that it followed existing 

regulations, guidance, and standard 

practices when conducting modeling, 

preparing the emissions inventories, 

and implementing its planning 

procedures. Therefore, the State did not 

use or request approval of alternative or 

equivalent techniques as allowed under 

of the CAA and EPA is proposing to 

conclude that the State’s nonattainment 

SIP meets the requirements of section 

172(c)(8) of the CAA. 

VII. EPA’s Proposed Action 

EPA has determined that New 

Hampshire’s SO2 nonattainment plan 

meets the applicable requirements of 

sections 110, 172, 191, and 192 of the 

CAA. EPA is proposing to approve New 

Hampshire’s January 31, 2017 SIP 

submission for attaining the 2010 1-hour 

SO2 NAAQS for the Central New 

Hampshire Nonattainment Area and for 

meeting other nonattainment area 

planning requirements. This SO2

nonattainment plan includes New 

Hampshire’s attainment demonstration 

for the SO2 nonattainment area. The 

nonattainment area plan also addresses 

requirements for RFP, RACT/RACM, 

enforceable emission limits and control 

measures, base-year and projection-year 

emission inventories, and contingency 

measures. 

In the January 31, 2017 submittal to 

EPA, New Hampshire included the 

applicable monitoring, testing, 

recordkeeping, and reporting 


jstallworth on DSKBBY8HB2PROD with PROPOSALS
Federal Register / Vol. 82, No. 187 / Thursday, September 28, 2017 / Proposed Rules 45253 

requirements contained in Merrimack 

Station’s permit, TP–0189, to 

demonstrate how compliance with 

Merrimack Station’s SO2 emission limit 

will be achieved and determined. EPA 

is proposing to approve into the New 

Hampshire SIP the provisions of 

Merrimack Station’s permit, TP–0189, 

that constitute the SO2 operating and 

emission limits and their associated 

monitoring, testing, recordkeeping, and 

reporting requirements. EPA is 

proposing to approve these provisions 

into the State’s SIP through 

incorporation by reference, as described 

in section VIII, below. EPA’s analysis is 

discussed in this proposed rulemaking. 

EPA is not proposing to remove from 

the existing New Hampshire SIP, Table 

4, items 6, 8, and 10 contained in 

Merrimack Station’s July 2011 permit, 

TP–0008, because EPA has not received 

a request from the State to do so. See 

52.1520(d) EPA-approved State Source 

specific requirements. However, EPA 

considers those provisions to be 

superseded by the conditions of TP– 

0189, which are more stringent, and 

which are to be incorporated into the 

SIP in this proposed action. 

Specifically, two of the provisions, 

items 6 and 8 from Table 4, relate to SO2

emissions limits that have been 

superseded by Merrimack Station’s 

September 2016 permit, TP–0189. Item 

10 from Table 4 has also been 

superseded by Merrimack Station’s 

September 2016 permit, TP–0189, in 

that the existing SIP provision allowed 

operation of one of Merrimack Station’s 

two boilers, MK1, for up to 840 hours 

in any consecutive 12-month period 

through the emergency bypass stack, 

i.e., not through the FGD. Each of the 

corresponding provisions of Merrimack 

Station’s September 2016 permit, TP– 

0189, are more stringent than those 

existing SIP provisions. EPA is taking 

public comments for thirty days 

following the publication of this 

proposed action in the Federal Register. 

We will take all comments into 

consideration in our final action. 

VIII. Incorporation by Reference 

In this rule, EPA is proposing to 

include in a final EPA rule regulatory 

text that includes incorporation by 

reference. In accordance with 

requirements of 1 CFR 51.5, EPA is 

proposing to incorporate by reference 

certain federally enforceable provisions 

of Merrimack Station’s permit, TP–0189, 

effective on September 1, 2016. 

Specifically, the following provisions of 

that permit are proposed to be 

incorporated by reference: Items 1, 2, 

and 3 in Table 4 (‘‘Operating and 

Emission Limits’’); items 1 and 2 in 

Table 5 (‘‘Monitoring and Testing 

Requirements’’); items 1 and 2 in Table 

6 (‘‘Recordkeeping Requirements’’); and 

items 1 and 2 in Table 7 (‘‘Reporting 

Requirements’’). 

EPA has made, and will continue to 

make, these materials generally 

available through www.regulations.gov 

and/or at the EPA Region 1 Office 

(please contact the person identified in 

the FOR FURTHER INFORMATION CONTACT

section of this preamble for more 

information). 

IX. Statutory and Executive Order 

Reviews 

Under the CAA, the Administrator is 

required to approve a SIP submission 

that complies with the provisions of the 

Act and applicable Federal regulations. 

42 U.S.C. 7410(k); 40 CFR 52.02(a). 

Thus, in reviewing SIP submissions, 

EPA’s role is to approve state choices, 

provided that they meet the criteria of 

the CAA. Accordingly, this proposed 

action merely approves state law as 

meeting Federal requirements and does 

not impose additional requirements 

beyond those imposed by state law. For 

that reason, this proposed 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) and 13563 (76 FR 3821, 

January 21, 2011); 

• does not impose an information 

collection burden under the provisions 

of the Paperwork Reduction Act (44 

U.S.C. 3501 et seq.); 

• is certified as not having a 

significant economic impact on a 

substantial number of small entities 

under the Regulatory Flexibility Act (5 

U.S.C. 601 et seq.); 

• does not contain any unfunded 

mandate or significantly or uniquely 

affect small governments, as described 

in the Unfunded Mandates Reform Act 

of 1995 (Pub. L. 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 Executive Order 

13045 (62 FR 19885, April 23, 1997); 

• is not a significant regulatory action 

subject to Executive Order 13211 (66 FR 

28355, May 22, 2001); 

• is not subject to requirements 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 CAA; and 

• does not provide EPA with the 

discretionary authority to address, as 

appropriate, disproportionate human 

health or environmental effects, using 

practicable and legally permissible 

methods, under Executive Order 12898 

(59 FR 7629, February 16, 1994). 

In addition, the SIP is not approved 

to apply on any Indian reservation land 

or in any other area where EPA or an 

Indian tribe has demonstrated that a 

tribe has jurisdiction. In those areas of 

Indian country, the rule does not have 

tribal implications and will not impose 

substantial direct costs on tribal 

governments or preempt tribal law as 

specified by Executive Order 13175 (65 

FR 67249, November 9, 2000). 

List of Subjects in 40 CFR Part 52 

Environmental protection, Air 

pollution control, Incorporation by 

Reference, Intergovernmental relations, 

Reporting and recordkeeping 

requirements, Sulfur oxides. 

Authority: 42 U.S.C. 7401 et seq. 

Dated: September 15, 2017. 

Ken Moraff, 

Acting Regional Administrator, EPA New 

England. 

[FR Doc. 2017–20721 Filed 9–27–17; 8:45 am] 

BILLING CODE 6560–50–P 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 82 

[EPA–HQ–OAR–2017–0213; FRL–9968–67– 

OAR] 

RIN 2060–AT43 

Protection of Stratospheric Ozone: 

Refrigerant Management Regulations 

for Small Cans of Motor Vehicle 

Refrigerant 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Proposed rule. 

SUMMARY: EPA is proposing this action 

to correct an editing oversight that lead 

to a potential conflict in a prior 

rulemaking as to whether or not 

containers holding two pounds or less 

of non-exempt substitute refrigerants for 

use in motor vehicle air conditioning 

that are not equipped with a self-sealing 

valve can be sold to persons that are not 

certified technicians, provided those 

small cans were manufactured or 

imported prior to January 1, 2018. This 

action clarifies that those small cans 

may continue to be sold to persons that 

are not certified as technicians under 

sections 608 or 609 of the Clean Air Act. 

In the ‘‘Rules and Regulations’’ section 

of this Federal Register, EPA is 

publishing this action as a direct final 


jstallworth on DSKBBY8HB2PROD with PROPOSALS