2018-20446. Adequacy Determination for the Missoula PM10

AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Adequacy determination.

SUMMARY:

In this announcement, the Environmental Protection Agency (EPA) is notifying the public that the EPA has found the Missoula PM₁₀ National Ambient Air Quality Standard (NAAQS) Limited Maintenance Plan (LMP) adequate for transportation conformity purposes. As more fully explained in the Supplementary Information section of this notice, this finding will affect future transportation conformity determinations.

DATES:

This finding is effective on October 12, 2018.

FOR FURTHER INFORMATION CONTACT:

Tim Russ, Air Program, EPA, Region 8, Mailcode 8P-AR, 1595 Wynkoop Street, Denver, Colorado 80202-1129, [phone], or [e-mail].

SUPPLEMENTARY INFORMATION:

Throughout this document wherever “we,” “us,” or “our” is used, we mean the EPA.

Transportation conformity is required by section 176(c) of the Clean Air Act to ensure that federally funded highway and transit projects are consistent with the air quality goals established by the state implementation plan (SIP). The EPA's conformity rule provisions at 40 CFR part 93, subpart A, establish the criteria and procedures for determining whether transportation plans, programs and projects conform to the SIP. Conformity to a SIP means that transportation activities will not produce new air quality violations, worsen existing violations, or delay timely attainment of the applicable NAAQS.^[1]

The criteria by which the EPA determines whether a SIP revision's LMP ^[2] or motor vehicle emission budgets (MVEBs) are adequate for transportation conformity purposes are outlined at 40 CFR 93.118(e)(4), and the adequacy review process is described at 40 CFR 93.118(f)(1). We applied these criteria and followed this process in making the determinations announced in this notice.

This document is simply an announcement of findings that the EPA has already made, as described below.

The State of Montana submitted the Missoula PM₁₀ LMP ^[3] on August 1, 2016. As part of our adequacy review, we announced receipt of the Missoula PM₁₀ LMP and posted an announcement of availability on the EPA Office of Transportation and Air Quality's transportation conformity website https://www.epa.gov/​state-and-local-transportation/​adequacy-review-state-implementation-plan-sip-submissions-conformity. The EPA requested public comments by May 30, 2018. We did not receive any comments. We sent a letter to the Montana Department of Environmental Quality on July 23, 2018, that stated that the submitted Missoula PM₁₀ LMP was adequate for transportation conformity purposes.

Following the effective date listed in the DATES section of this notice, the Missoula County-City Metropolitan Planning Organization, the Montana Department of Transportation, and the U.S. Department of Transportation are required to use the provisions of the Missoula PM₁₀ LMP for future transportation conformity determinations for projects in the Missoula PM₁₀ nonattainment area. Please refer to 40 CFR 81.327 for a description of the nonattainment area boundary. On the effective date of this adequacy determination, the previously-approved PM₁₀ MVEB of 16,119 pounds per day of PM₁₀^[4] for the Missoula PM₁₀ NAAQS nonattainment area will no longer be applicable for transportation conformity purposes.

Please note that our adequacy review of the LMP for transportation conformity is separate from our future rulemaking action on the Missoula PM₁₀ redesignation request and LMP SIP revision and should not be used to prejudge our ultimate approval or disapproval of that SIP revision. Even if we find the Missoula PM₁₀ LMP adequate for transportation conformity purposes now, we may later find it necessary to disapprove the SIP revision. Should this situation arise, we would revisit our adequacy finding.

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

Dated: September 14, 2018.

Douglas Benevento,

Regional Administrator, EPA Region 8.

Footnotes

1.  The applicable PM₁₀ NAAQS is found in 40 CFR part 50, section 50.6: “The level of the national primary and secondary 24-hour ambient air quality standards for particulate matter is 150 micrograms per cubic meter (µg/m3. ), 24-hour average concentration. The standards are attained when the expected number of days per calendar year with a 24-hour average concentration above 150 µg/m3. , as determined in accordance with appendix K to this part, is equal to or less than one.”

2.  On August 9, 2001, EPA issued a guidance memorandum titled “Limited Maintenance Plan Option for Moderate PM₁₀ Nonattainment Areas.” https://www.epa.gov/​sites/​production/​files/​2016-06/​documents/​2001lmp-pm10.pdf.

3.  Particulate matter less than or equal to 10 microns in diameter.

4.  The PM₁₀ MVEB was originally derived from the motor vehicle source category of the emissions inventory for the Missoula PM₁₀ nonattainment area; see the EPA 's SIP approvals of December 13, 1994 (59 FR 64133) and August 30, 1995 (60 FR 45051.)