# E~stern 

# ?(ern Air Pollution Control District 

# Dae~C?.fo!YsE0 Air Pollution

**Con)WG~et012**


### August 21,2012
Gerardo Rios Chief, Air Permits Office (Air-3) EPA Region 9 75 Hawthorne Street San Francisco, CA 94105
SUBJECT: Additional Clarifications for Rule 210.4 and 40 CFR 51.166 Dear Mr. Rios: Pennits Oftice Alr-3 

### U.S. EPA. Region 9

This letter is in response to your request for additional information regarding Eastern Kern Air Pollution Control District (District) Rule 210.4 PSD. In a letter dated July 19, 2012, we responded to your initial request for clarifications regarding Rule 210.4 and the requirements for a Prevention ofSignificant Deterioration (PSD) permitting program. Belowwe provide an additional clarificationregarding Rule 210.4. To implementthe PSD permitting program under the Clean Air Act (CAA), the District incorporated section 40 CFR 52.21(k)(2) ofEPA's regulations by reference into Rule 210.4 and included this provision as partofa SIP revision submitted to EPA for approval. The District understands that EPA has recently stated, in response to litigation, that EPA intends to revise its PSD permitting regulations at 40 CFR 51.166(k)(2) and 40 CFR 52.21(k)(2) to ensure that these provisions are consistent withEPA statements in the supporting rulemaking record and the CAA. In light ofEPA'sresponse to the litigation and in orderto ensure that permitting actions by the District are consistent with the CAA, I am writing to clarify that the District interprets and intends to apply the PSD program provisions in the District's portion ofthe California SIP in a manner that is consistent with certain EPA statements included inthe preamble ofthe 2010 final rule that added section 52.2l(k)(2) to the federal regulations. Section 52.21(k)(2) establishes SignificantImpact Levels (SILs) for PM2.s and reads as follows: (k)(2) Significant impact levels. 

### Forpurposes ofPM25, the demonstrationrequired in paragraph (k)(l) ofthis section is deemed to have been made ifthe emissions increase from the new stationary source alone or from the modification alone would cause, in all areas, air quality impacts less thanthe following amounts:

Administrative Office: 2700 "M" Street, Suite 302, Bakersfield, CA 93301-2370 Phone (661) 862-5250- Fax (66/) 862-5251

www.kernair.org- ekapcd@co.kern.ca.us

### EKAPCDRule 210.4 August21, 2012 Page2

Pollutant PM2.s
................. Averaging time Annual
............ 24-hour
........... Class I area Class II area Class III area 0.06j.!g/mj 0.3 jlg/mj 0.3 11g/mj 0.07 jlg/mj 1.2 jlg/mj 1.2jlg/mJ Paragraph (k)(l) requires that sources applying for a newPSD permit demonstrate that any allowable emission increases from the proposed source or modification, in conjunctionwith all other applicable emissions increases orreductions, will not cause orcontribute to a violation of any NAAQS or any applicable increment. In the preamble to the 2010 final rule adding the (k)(2) provision, EPA advised that, "notwithstanding the existence ofa SIL, permitting authorities should determine when it maybe appropriate to conclude that even a 

### de minimis impact will 'cause or contribute' to an air quality problem and to seekremedial action from the proposed new source or modification." PSD for Particulate Matter Less than 2.5 Micrometers (PM2.5)- Increments, SILs and Significant Monitoring Concentration (SMC), 75 Fed. Reg. 64,864,64,892 (Oct. 20, 2010). In another passage ofthepreamble, EPA also observed that "the use ofa SIL maynotbe appropriate when a substantialportion ofany NAAQS or increment is knownto be consumed." Id. at 64,894. Consistent withthese statements byEPA in the preamble to the 2010 final rule, the District does not interpret section 52.21(k)(2) to preclude the District from exercising the discretion to determine when it maybe appropriate to conclude thateven a 

### de minimis impact on air quality (an impactbelowthe PM2.s SIL values) will cause or contribute to an air quality problem and to seekremedial action from theproposed new source ormodification. Based onthis interpretation, the District will not read section 52.21(k)(2) as an absolute "safe harbor," but will exercise discretion to determine whether a particular application ofthe PM2.s SILs is appropriate when a substantial portion ofthe PM2.s NAAQS or increment is knownto be consumed. The Districtretains the discretion to require additional information from a permit applicant as needed to assure that the source will not cause or contribute to a violation ofanyNAAQS or applicable incrementpursuant to paragraph 52.21(k)(1). Our expectation is thatthe need for the Districtto exercise this discretion will only arise in limited circumstances. The District looks forward to receiving additional guidance from EPA on howto identify when a permitting authority should exercise this type ofdiscretion before applying the PM2 .5 SILs in section 52.21(k)(2) to support a demonstrationthat a source will not cause or contribute to a violation ofthe PM2.s NAAQS and increments. Sincerely,

Air Pollution Control Officer DLJ: JC: dm