## Department of Environmental

Conservation

OFFICE OF THE COMMISSIONER

Post Office Box 111800 410 Willoughby Avenue, Suite 303

Juneau, Alaska 99811-1800

Main: 907.465.5066

Fax: 907.465.5070 14.022 February 12, 2014

Dennis McLerran Regional Administrator U.S. EPA Region 10

1200 Sixth Avenue

Seattle WA 98101

Significant Impact Levels (SILs)/Signi ficant Monitoring Concentration (SMC)

Dear Mr. McLerran:

The Alaska Department of Environmental Conservati on (ADEC) submits this letter in response to the Environmental Protection Agency (EPA), Region 10’s (R 10’s) concerns about the PM-2.5 Significant Impact Levels (SILs) and Significant Monitoring Concentr ation (SMC) provisions in ADEC’s Air Quality Regulations, 18 AAC 50, which have been submitted to R10 for State Implementation Plan approval.

ADEC adopted the PM-2.5 SIL provisions in 40 CFR 52 .21(k)(2) and the PM-2.5 SM C provisions in 40 CFR 52.21(i)5)(i)(c), as revised as of July 1, 2011, in the 18 AAC 50 regulations that went into effect on January 4,

2013. ADEC submitted these 18 AAC 50 revisions to R1 0 for SIP approval on January 24, 2013. However, on January 22, 2013, the U.S. Court of A ppeals for the District of Columbia, in Sierra Club v. EPA , 705 F.3d 458, vacated and remanded the provisions at 40 CFR 51.166(k)(2) and 40 CF R 52.21(k)(2) (concerning implementation of the PM-2.5 SILs) and vacated th e provisions at 40 CFR 51.166(i)(5)(i)(c) and 40 CFR 52.21(i)(5)(i)(c) (adding the PM-2.5 SM C) that were promulgated as part of the 2010 PM-2.5 PSD Rule. 1 On December 9, 2013, EPA published a Federal Register not ice (78 FR 73698) amending its regulations to

remove the vacated and remanded PM-2.5 SILs and the vacated PM-2.5 SMC provisions from the Code of Federal Regulations.

Therefore, at this time, ADEC withdraws the PM-2.5 SIL provisions found in 40 CFR 52.21(k)(2) and the

PM-2.5 SMC provisions found in 40 CFR 52.21(i)5)(i)(c), as adopted by reference in 18 AAC 50.040(h), effective January 4, 2013, from our request to R10 fo r approval of the SIP submittal of January 24, 2013.

ADEC made additional revisions to 18 AAC 50.215(d) regarding the ambient standard and Class II SILs as

follows:

 effective September 17, 2011 (submitted October 17, 2011)

o included under Table 5 the annual and 24-hou r PM-2.5 SILs and a 1-hour sulfur dioxide (SO 2 ) SIL in a general listing of the ambient stan dard and Class II SILs and changed “time” to “period” in the text of 18 AAC 50.215(d);

1 “Prevention of Significant Deterioration (PSD) for Particulate Matter Less than 2.5 Micrometers (PM 2.5 ) – Increments, Significant Impact Levels (SILs) and Significant Monitoring C oncentration (SMC),” 75 FR 64864 (October 20, 2010).Dennis McLerran 2 February 12, 2014

 effective September 14, 2012 (submitted December 6, 2012)

o revised the discussion concerning the method by which modeled concentrations should be compared to SILs; and

 effective January 4, 2013 (submitted January 24, 2013)

o added the two PM-2.5 averaging periods to the general discussion regarding the comparison of

modeled concentrations to the PM-2.5 SILs and included a 1-hour nitrogen dioxide (NO 2 ) SIL under Table 5 in a general listing of the ambient standard and Class II SILs.

An additional revision to 18 AAC 50.215(d), effective July 25, 2008, was solely a formatting change to Table 5. Therefore, at this time, ADEC withdraws from our requests to R10 for SIP approval the revisions to 18 AAC 50.215(d) which became effective on September 17, 2011 (submitted Octobe r 17, 2011); September 14, 2012 (submitted December 6, 2012); and Janu ary 4, 2013 (submitted January 24, 2013).

ADEC realizes that it will need to revise the general SIL language in 18 AAC 50.215(d). However, ADEC is also aware that EPA intends to issue guidance soon that will address the court’s concerns about PSD modeling applications. ADEC therefore plans to review EPA’s upcoming guidance to determine whether similar language could be proposed for 18 AAC 50.215(d ). If not, ADEC intends to develop and propose alternative language that would allow the SILs to be appropriately used in both of Alaska’s minor and major new source review permit programs and to begin th e public notice and comment process at the first opportunity.

In light of the above-described court decision, and un til ADEC has revised its regulations, ADEC permitting staff is advising permit applicants to not rely on the provisions regarding Cl ass I PM-2.5 SILs and SMC in preparing applications. ADEC is allowing continue d use of the Class II and ambient standard SILs in

18 AAC 50.215(d) – which is consistent with EPA guidance – but is informing applicants regarding the

court’s concern. 2 In the PSD Modeling Protocol Outline for PSD Permit Applicat ions, available to applicants on our Modeling webpage at http://dec.alaska.gov/air/ap/modeling.htm , ADEC footnotes the discussions of SILs (footnote 2) and SMC (footnote 3) on page 11 as follows:

2 In January 2013, the District of Columbia Circuit Court of Appeals remanded the federal PM-2.5 SILs back to EPA. While the State SIL provisions in 18 AAC 50.215(d) still stand, the PM-2.5 SILs could nevertheless be subject to challenge due to this federal ruling. Regulatory changes may be forthcoming from EPA and/or ADEC. Check the EPA and ADEC websites for possible updates regarding this issue.

3 In January 2013, the District of Columbia Ci rcuit Court of Appeals vacated the PM-2.5

SMC.

In the Modeling Review Procedures Manual (rev. June 30, 2013), also available on the Modeling webpage,

ADEC discusses the revocation of the PM-2.5 SILs (footnote 3 on page 13) and SMC (fourth paragraph on page 33). Although this document is used by staff, it also is available to the public in order that applicants can see how ADEC staff is addressing the vacature and remand of these provisions when reviewing modeling submissions. The relevant portions of the Manual read as follows:

3 In January 2013, the District of Columbia Circuit Court of Appeals revoked the PM-2.5 SIL. Regulatory changes may be forthcoming from EPA and/or ADEC. Check EPA and

2 EPA does not prohibit States from usin g the SILs. In its guidance dated March 2013, EPA wrote, “In the interim, the EPA believes permitting authorities may continue to apply SILs fo r PM2.5 to support a PSD permitting decision, but permitting

authorities should take care to ensure that SILs are not used in a manner that is inconsistent with the requirements of Section 165(a)(3) of the CAA.” (page 11).Dennis McLerran 3 February 12, 2014

ADEC websites periodically and before you be gin a review to see if new regulations have been put in place.

(p. 33) The third method is to submit a modeling analysis that shows the project impacts are below the SMC for each of the PSD-triggered pollu tants. If the predicted impact is less than the SMC for that pollutant, then the project impact may be considered too small to accurately detect with current monitoring techni ques. ADEC may then generally consider the SMC analysis as adequate for meeting the pre-construction monitoring requirement. However, the SMC for PM-2.5 was vacated on Ja nuary 22, 2013 by the District of Columbia Circuit Court. Therefore, projects that trigge r PSD review for PM-2.5 must include [ ] preconstruction PM-2.5 data, rega rdless of the project impacts.

ADEC will continue to work with PSD applicants to make sure the Court’s SIL concerns are addressed in situations where a substantial portion of the PM-2.5 NAAQS or increment is known to be consumed. Additionally, ADEC is requiring all PSD applicants w ho have triggered the PM-2.5 requirements to submit ambient PM-2.5 monitoring data in accordance with the Clean Air Act requirements. Applicants may no longer submit a PM-2.5 SMC demonstration in lieu of providing ambient PM-2.5 data.

If you have any questions or require additional information, please contact Alice Edwards at (907) 465-5105.

Sincerely,

Larry Hartig

Commissioner

cc: Debra Suzuki, EPA Region 10 Kristin Hall, EPA Region 10 Donna Deneen, EPA Region 10 Alice Edwards, Division of Air Quality, ADEC John Kuterbach, Air Permits Pr ogram, Division of Air Quality, ADEC