UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

REGION6 

. Mr. Doug Szenher 

1445 ROSS AVENUE, SUITE 1200 

DALLAS, TX 75202-2733 

MAR 2 2 2011 

Arkansas Department of Environmental Quality 

POA Division 

5301 Northshore Drive 

NorthLittleRock,AR 72118 

RE: U.S. Environmental Protection Agency (EPA) Comments on Proposed Revisions to the 

Arkansas Regulations 19 and 26 for the Greenhouse Gas (GHG) Tailoring Rule 

Dear Mr. Szenher: 

Thank you for providing us the opportunity to review and comment on the proposed 

revisions to Regulations 19 and 26 of the Arkansas Air Pollution Code. The proposed 

rulemaking revises the Arkansas prevention of significant deterioration (PSD) and title V 

programs to establish the greenhouse gas-specific permitting thresholds in EPA's final rule 

''Prevention of Significant Deterioration and Title V Greenhouse Gas Tailoring Rule" published 

on June 3, 2010 (see 75 FR 31514). 

We are supportive of the proposed rule revisions, but note that there are several 

significant differences between the proposed Arkansas revisions and the federal GHG Tailoring 

Rule provisions at 40 Code ofFederal Regulations (CFR) 52.21 and 70.2 as outlined in our 

enclosed comments. These areas of difference must be corrected for the Arkansas program to 

implement the GHG thresholds as EPA intended. 

We encourage the Arkansas Department of Environmental Quality (ADEQ) to adopt 

these revisions with the corrections identified in the enclosure to correctly implement the GHG 

Tailoring Rule provisions in the state of Arkansas. We would appreciate the opportunity to 

review the revised rulemaking language prior to adoption to ensure the revisions address our 

concerns and adequately implement the GHG Tailoring Rule provisions. 

We appreciate the timely efforts by ADEQ to update the PSD and title V programs and 

its.willingness to consult EPA Region 6 throughout this process. We look forward to future 

collaboration with ADEQ on the implementation of the GHG Tailoring Rule. If you have any 
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questions about the GHG Tailoring Rule, or about EPA's review of your proposed rulemaking, 

please feel free to contact me at (214) 665-6435 or contact Ms. Adina Wiley of my staff at 

(214) 665-2115. 

Enclosure 

Sincerely yours, 

Y'~4- JeffRobinson 

Chief 

Air Permits Section 
1 

Enclosure 

I. The definition of"C02 Equivalent Emissions" at Regulation 19, Chapter 2 includes the 

incorporation date of October 30, 2009. We note that it will be ADEQ's responsibility to 

monitor Table A-1 to subpart A of 40 CPR Part 98 for updates and to initiate rulernaking 

accordingly pursuant to all applicable state implementation plan (SIP) revision 

requirements. 

2. The definition of"greenhouse gases" at Regulation 19, Chapter 2, should be revised to 

mirror the definition of"greenhouse gases" at Regulation 19, Section 19.904(0)(1). 

Additionally, this definition must be revised to remove the reference to measuring in 

C02e because C02e is one of two steps used in conjunction with major source mass 

thresholds to determine whether a source is subject to regulation for its GHG emissions. 

We suggest the following revisions to this definition: 

"Greenhouse gases" (GHGs) is the air pollutant defined as the aggregate group of 

six greenhouse gases: carbon dioxide, nitrous oxide, methane, hydro fluorocarbons, 

perfluorocarbons, and sulfur hexafluoride, 1111d slialllle mell&llf'ed BB COOe. 

3. EPA does not support the proposed revisions to Regulation 19, Section 

19.407(C)(2)(a)(vi). While an emission source with a potential to emit (PTE) less than 

the 75,000 tpy C02e will in practical effect be excluded from regulatory consideration in 

a way that may equate to the treatment of de minimis emission levels, the significance 

levels established in the Tailoring Rule are not by nature considered de minimis by EPA. 

See 75 FRat 31560. EPA approaches GHG applicability in two steps. First, EPA uses 

the phased-in GHG permitting thresholds to determine if the source's GHG emissions are 

subject to regulation. Then, EPA determines whether the source has a PTE that is at or 

above the Clean Air Act major source thresholds for GHGs. More information about 

EPA's use of the permitting thresholds for determining subject to regulation is available 

in the March 15, 2011, GHG Permitting Questions and Answers posted at 

www.epa.gov/nsr/ghgqa. 

4. Regulation 19.904(G) refers to the permitting ofC02e emissions. We note that the PSD 

program does not permit C02e emissions, but instead permits GHG emissions that are 

subject to regulation. C02e is not in itself a pollutant subject to regulation under PSD; 

C02e is one of two steps used to determine if a source's GHG emissions are subject to 

PSD permitting. 

5. Regulation 19.904(G) also includes the incorporation dates of November 29, 2005, and 

June 3, 2010. We note that it will be ADEQ's responsibility to monitor the referenced 

provisions of 40 CFR 52.21 for updates and initiate rulemaking accordingly pursuant to 

all applicable SIP revision requirements. 

6. The definition of"C02 Equivalent Emissions" at Regulation 19, Section 19.904(GX 1) 

includes the incorporation date of October 30, 2009. We note that it will be ADEQ's 

responsibility to monitor Table A-1 to subpart A of 40 CFR Part 98 for updates and 

initiate rulemaking accordingly pursuant to all applicable SIP revision requirements. 
2 

7. Regulation 19, Section 19.904(0)(3) includes the incorporation date of 

November 29, 2005. We note that it will be ADEQ's responsibility to monitor the 

referenced provisions of 40 CFR 52.21 for updates and initiate rulemaking accordingly 

pursuant to all applicable SIP revision requirements. 

8. Regulation 19, Section 19.904(0)~3) also includes the following typo: "a significant 

emissions increase (as calculated using the procedures in 40 CFR 52.21(a)(2)(iv), as of 

November 29, 2005), and a significant net emissions increase (as defined in 40 CFR 

52.21(b)(3), as ofNovember 29,2005, and 40 CFR 52.21(b)(23), as of 

November 29, 2005), occur." 

9. Regulation 9, Chapter 9, Appendix A, Insignificant Activities List, Group A, Sections 1 

and 13 states that certain activities less than 75,000 tpy C02 are considered insignificant. 

We note that C02 is only one of six pollutants analyzed in the aggregate to determine 

GHG emissions. Additionally, the insignificant activity list exclusions need to be based 

both on the same major source 100/250 tpy thresholds and the C02e thresholds used to 

determine whether a source is subject to regulation for PSD permitting. 

10. We also recommend the following addition to improve clarity at Group A, Section 13: 

"or 5 tpy of anyJl!Wa:.air pollutant regulated under this regulation. These emission limits 

apply to the sum of all activities listed under this group." 

11. EPA believes the addition of new subsection M under the definition of"applicable 

requirement" at Regulation 26, Chapter 2, would be better situated under the new 

subsection of GHGs under the definition of''regulated air pollutant". The definition of 

"applicable requirement" already appears to cover GHG permitting under subsections A 

and B as Title I requirements. Further, we note that as in comment 4 above, the title V 

program does not permit C02e emissions, but instead permits GHG emissions that are 

subject to regulation. C02e is not in itself a pollutant subject to regulation under title V; 

C02e is one of two steps used to determine if a source's GHG emissions are subject to 

title V permitting. 

12. The definition of"C02 Equivalent Emissions" at Regulation 26, Chapter 2 includes the 

incorporation date of October 30, 2009. We note that it will be ADEQ's responsibility to 

monitor Table A-1 to subpart A of 40 CFR Part 98 for updates and to initiate rulernaking 

accordingly pursuant to all applicable title V revision requirements. 

13. The definition of"greenhouse gases" at Regulation 26, Chapter 2, should be revised to 

mirror the definition of "greenhouse gases" used throughout Regulation 19 to promote 

internal consistency. We suggest the following revisions to this definition: 

"Greenhouse gases" (GHGs) is the air pollutant defmed as the aggregate group 

of six greenhouse gases: carbon dioxide, nitrous oxide, methane, 

hydro fluorocarbons, perfluorocarbons, and sulfur hexafluoride. 
3 

14. The revised definition of"major source" at Regulation 26, Chapter 2 appears to limit 

major source applicability under title V to a source that has both l 00,000 tpy C02e and 

I 00 tpy of any regulated pollutant; essentially this means a source is only major for 

title V if it can be considered major for GHG emissions. EPA believes that the clearest 

option for resolving this concern is to revise the definition of"major source" pursuant to 

the revisions at 40 CFR 70.2 to include the phrase" any regulated air pollutant subject to 

regulation". Then as explained below, the definition of"subject to regulation" could be 

added to the Regulation 26 definitions. 

15. EPA believes that the inclusion of the "subject to regulation" language at 40 CFR 70.2 

would greatly improve clarity of the Arkansas regulations. We think that ADEQ could 

either add this as a separate Regulation 26 definition or include this under the new 

subsection for GHGs under the definition of"regulated air pollutant". 

16. The revisions to Regulation 26, Section 26.302 do not adequately address the two step 

approach used to determine whether a source is subject to title V permitting. In addition 

to emitting at or above the 100,000 tpy C02e threshold, a source must also be a major 

title V source with I 00 tpy of GHG emissions. We note that if the ADEQ chooses to 

correct the definition of"major source" as discussed above in comment 14 it is likely that 

Section 26.302 will not need to be revised. 

17. EPA is concerned about the revisions to Regulation 26, Section 26.305. We interpret the 

purpose of this revision to exclude from inclusion in the title V permit emissions ofGHG 

that are not major for PSD. If that is the case, the revision need to reference both the 

C02e threshold to determine a source is subject to regulation and the l 00/250 tpy major 

source threshold for determining whether the source is major for PSD permitting. 

Additionally, we have concerns that this provision will preclude a source from taking 

synthetic minor limits to avoid major source applicability. 

18. EPA interprets the revisions to the minor permit modification procedures at Regulation 

26, Section 26.1002 to apply to sources that are minor for PSD permitting requirements. 

If that is the correct interpretation, this provision must be revised to reflect the usage of 

C02e to determine if the source is subject to regulation and then the 100/250 tpy major 

source thresholds to determine if the source is major for PSD.