UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 
REGION 10 


1200 Sixth Avenue. Suite 900 
Seattle. WA 98101-3140 

OFFICE OF 
AIR. WASTE AND TOXICS 

November 24,2010 

Reply To 
Attn Of: AWT-I07 

Ms. Jill Inahara 
Program Operations 
Washington Department ofEcology 
811 SW 6th Avenue 
Portland Oregon 97204 

Re: EPA's Comments on the Proposed Revisions to Oregon Department ofEnvironmental 
Quality's (ODEQ's) New Source Review, Particulate Matter, Greenhouse Gas and Other 
Permitting Regulations 

Dear Ms. lnahara: 

Thank you for the opportunity to review and comment on ODEQ's proposed rule revisions, 
dated October 15,2010. Our comments on these revisions follow: 

General Comments 

In submitting these comments, EPA's review focused on the changes to regulations proposed in 
this rulemaking. Importantly, provisions ofcurrent regulations not open for comment in this rulemaking 
may affect the approvability ofthe regulation changes in this proposed rulemaking. 

Please also note that these comments contain our current views based on a preliminary review 
of the proposed rule. These views should not be considered EPA's final position, which we will reach 
only through notice and comment rulemaking after the state has submitted a rule for our approval as a 
SIP revision. 

OAR 340-200-0020(3)(b): Under the definition of "Actual Emissions", paragraph 
0020(3)(b) should be amended to read " ....but was permitted or approved to construct and 
operate .... "to be consistent with the previous paragraph 0020(3)(a)(C). 

OAR 340-200-0020(7)(h): The revision to the definition of"Aggregate insignificant 
emissions" adding a threshold for greenhouse gases needs to include language indicating that the 
1000 short tons value is measured as C02 equivalent (C02~e). A mass GHG threshold of 1000 
tons could be a major source (e.g., if all 1000 tons on a mass basis was nitrous oxide it would be 
equal to 310,000 tons C02 e), not an insignificant source. 

OAR 340-200-0020(54): The revision to the definition of"Federal Major Source" is not 
consistent with the EPA requirements as set forth in the "Tailoring Rule." The Tailoring Rule 



did not change the size thresholds that define a Federal Major Source. Major sources are still 
determined based on the potential to emit 100 or 250 tons per year or more of a regulated 
pollutant on a mass basis. The Tailoring Rule only changed the definition of"regulated NSR 
pollutant" by adding a new definition that clarified when a pollutant, and specifically GHGs, was 
"subject to regulation" under the Act. GHGs are only subject to regulation under the Act when 
they exceed certain thresholds based on a C02 equivalent (C02 e) basis, not a mass basis. Small 
quantities ofGHGs, far lower than 100 tpy on a mass basis, will be subject to regulation under 
the Act because they exceed 100,000 tpy on a C02e basis (e.g., 4.1841 tpy mass basis of sulfur 
hexafluoride (SF6) equals 100,000 tpy C02e). But a source that has the potential to emit 4.2 tons 
per year ofSF6on a mass basis is not a Federal Major Source because it doesn't exceed the 
1001250 tpy mass threshold. Essentially, there is a two-part test in order to determine a Federal 
Major Source with respect to GHGs. First, GHGs must be a regulated air pollutant that is the 
source must have the potential to emit 100,000 tpy or more on a C02 equivalent (C02 e) basis. 
Then the source must also have the potential to emit 100 or 250 tpy or more on a mass basis. 

EP A sees two options for revising this definition. One would be to drop the new 
language regarding GHGs and add language to the definition of'~regulated air pollutant" similar 
to what is being added to the applicability provisions ofDivision 224 (specifically, the new 
language at 224-001 0(5�. Then it would be clear when GHGs are a regulated pollutant and the 
existing 100 and 250 tpy mass thresholds would be applied per this definition. The second 
option would be to replace the new language here with language that states that, for GHGs, in 
addition to having PTE greater than or equal to 100 or 250 tpy on a mass basis, the source must 
also have PTE greater than or equal to 100,000 tpy on a C02 equivalent (C02 e) basis. 

OAR 340-200-0020(70): The revision to the definition of"Major Source" has the same 
problem as the revised definition of"Federal Major Source" in that it doesn't correctly reflect the 
two-part test for GHGs. In addition, the 100,000 tpy threshold needs to include language 
specifying that it is measured as C02 equivalent (C02 e). 

OAR 340-200-0020(84): The new definition of"Ozone Precursor" should include 
language regarding the measurement methods similar to the language in the definition of"PM10" 
when used in context ofemissions (or the new language regarding PM2.5 precursor emissions) 
especially to distinguish between ambient N02 and NOx emissions. 

OAR 340-200-0020(95)(b): We assume ODEQ removed the conditional test method 
(CTM) citation because CTMs are no longer being developed. We recommend that other test 
method (OTM) 027 for PM2.5 and PMlO, that has superceded CTM 040, be cited here. As with 
the current definitions of "PM" and "PMlO," this definition needs to reference the appropriate 
EPA or ODEQ emissions measurement method in order to distinguish ambient PM2.5 from PM2.5 
emissions. 

OAR 340-200-0020(103)(a)(B): It isn't clear that the provision in the definition of 
"Regulated air pollutant" or "Regulated Pollutant" that references the national ambient air 
quality standards ((103)(a)(B� includes any precursors to such pollutants. This should be 
clarified in the text. 

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OAR 340-200-0020(148)(d): Note that paragraph (d) in the definition of44Volatile 
Organic Compounds" appears to be missing the last line. The EPA definition ofthe term in 40 
CFRSl.100 includes a few more words and the identification of the actual compound subject to 
the provision. 

OAR 340-200, new Table 1: The new Table 1 SIGNIFICANT AIR QUALITY 
IMP ACT includes Class III impact levels for S02 that are higher than the Class II impact levels 
established by EPA in 40 CFR S1.16S(b) (all other Class II and Class III impact levels are the 
same). Oregon will need to submit a demonstration that such higher levels will still ensure 
protection ofthe NAAQS in Class III areas. We also note that both the Class II and Class III 
levels for PMto and PM2.5 are lower than the EPA levels for those pollutants in 40 CFR SI.165(b) 
(for PMto) and S1.166(k)(2) (for PM2.5). 

Also new Table 1 specifies Significant Air Quality Impact values for PM2.5 of0.2 llg/m3 
(annual arithmetic mean) and 1.0 llg/m3 (24-hour average) respectively. These differ from the 
corresponding Class II and III areas PM2.5 SILs of0.3 llg/m3 (annual arithmetic mean) and 1.2 
llg/m3 (24-hour average) established by EPA and published in the Federal Register on October 
20, 201 0 (FR 64864). Please clarify why these values are different? 

OAR 340-202-0210, Table 1: There is a typo in Table 1. For Class I areas, the PMto 
increments should be 4 and 8 J.lg/m3respectively for the annual arithmetic mean and 24-hour 
maximum respectively. 

OAR 340-216-0020, Table 1 Part C (No.5): It must be clear that the 100,000 tons of 
GHG here is in terms ofC02 equivalent (C02e), not mass emissions. See comments on OAR 
340-200 above regarding GHG emission thresholds. 

OAR 340-224-0010(5): This new applicability provision for GHGs needs to include 
language indicating that the 75,000 tpy value is measured as C02 equivalent (C02 e). 

OAR 340-224-0010(6): This new applicability provision for GHGs needs to include language 
indicating that the 100,000 tpy value is measured as C02 equivalent (C02e) and that a new 
stationary source �001O)(6)(a� or an existing stationary source �001O)(6)(b� is subject to 
regulation when it emits, will emit, or has the potential to emit 1 00,000 tpy or more 

OAR 340-224-0050(3): The additional requirements for sources in nonattainment areas 
are only required to apply to sources that are major for the nonattainment pollutant. Since GHGs 
are not criteria pollutants and never will be nonattainment pollutants, these provisions need not 
apply to GHGs. However, ifODEQ does include GHGs here, it needs to include language 
indicating that the 100,000 tpy value is measured as C02 equivalent (C02e). See also comments 
in OAR 340-200 above on GHG emission thresholds. 

OAR 340-224-0060(1): For consistency and accuracy, the text in 0060(1) should be 
amended to read " ... must apply BACTJar each maintenance pollutant or precursor(s) emitted at 
or above a SER. " 

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OAR 340-224-0070(2)(a): To be consistent with paragraph 0070(2), paragraph 
0070(2)(a) should be amended to read "For increases ojPM2.5precursors equal to or greater 
than the precursor significant emission rate, .... ". 

OAR 340 224-0070(5): It is not clear why this new provision for sources impacting 
PM2.5 nonattainment areas is necessary. It appears to duplicate the requirement of 340-2240070(
2)(b). Since 340-224-0050(2) refers to 340-225-0090 both 0070(2)(b) and this new 
0070(5) appear to require the same thing. 

OAR 340-225-0020(3)(a): The clarification to the definition of"baseline concentration" 
is consistent with EPA's definition and the definition in section 169 ofthe Act. When 
submitting this regulation as a SIP revision, Oregon must demonstrate that the regulation is 
consistent with previous interpretations so it cannot be construed to be a relaxation. The old 
language could be interpreted to mean that all emission increases from new sources and 
modifications occurring after January 6, 1975 but before January 1, 1978 consume increment, 
while the new language could be interpreted to mean that only emission increases from major 
new sources and major modifications consume increment. 

OAR 340-225-0090(2)(a)(D)(ii): Even with the conditions provided in this paragraph, it 
may be too broad an assertion to state that a small-scale local energy project and associated 
infrastructure provides a net air quality benefit without conducting air quality dispersion 
modeling to confirm this. We are not aware ofsimilar provisions in the SIPs ofother states. 
Therefore, before Region 10 can consider this for inclusion in the Oregon SIP, we will need to 
consult with EPA Headquarters and other Regions. 

Again, thank you for the opportunity to comment. If you have any questions or concerns 
regarding this letter or would like to discuss these matters further, please contact me at (206)553-
0296. 

Sincerely, 

~j~

Environmental Engineer 
State and Tribal Air Programs Unit 

Enclosures 

c: Debra Suzuki, EPA Region 10 
Julie Vergeront, EPA Region 10 
Dave Bray, EPA Region 10 

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