Approval and Promulgation of State Implementation Plans; North Dakota; Notice of Potential Violations of the Prevention of Significant Deterioration Increments

AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Information notice.

SUMMARY:

North Dakota has conducted a draft modeling analysis that shows numerous violations of the Class I prevention of significant deterioration (PSD) increments for sulfur dioxide (SO₂) in four Class I areas. Those Class I areas include Theodore Roosevelt National Park, the Lostwood Wilderness Area, the Medicine Lakes Wilderness Area, and the Fort Peck Class I Indian Reservation. In a March 13, 2001 letter to EPA, the North Dakota Department of Health has committed to refine this modeling analysis and to subsequently adopt revisions to the State Implementation Plan (SIP) as may be necessary to address the increment violations that may be shown by the revised analysis. The purpose of this document is to inform the public of potential increment violations and of the commitments made by the North Dakota Department of Health to address the potential violations.

EFFECTIVE DATE:

May 29, 2001.

ADDRESSES:

Relevant documents are available for public inspection during normal business hours at the Air and Radiation Program, Environmental Protection Agency, Region VIII, 999 18th Street, Suite 300, Denver, Colorado 80202-2405. Interested persons should contact the person listed below to arrange for a mutually agreeable time to view these documents.

FOR FURTHER INFORMATION CONTACT:

Amy Platt, Air and Radiation Program, Environmental Protection Agency, Region VIII, (303) 312-6449.

SUPPLEMENTARY INFORMATION:

I. What Is the Purpose of This Document?

The purpose of this document is to inform the public of the commitments made by the North Dakota Department of Health regarding draft modeling studies that have shown violations of the PSD increment for SO₂ in four Class I areas. Those Class I areas include Theodore Roosevelt National Park and the Lostwood Wilderness Area, both of which are in North Dakota, and the Medicine Lakes Wilderness Area and the Fort Peck Class I Indian Reservation, both of which are within the State of Montana. In a March 13, 2001 letter to EPA, the North Dakota Department of Health has committed to refine this modeling analysis and to subsequently adopt revisions to its SIP as may be necessary to address the increment violations that may be shown by the revised modeling analysis. Specifically, the North Dakota Department of Health made the following commitments:

• By April 1, 2001—The State will develop an air quality modeling protocol.
• By January 2, 2002—The State will complete its modeling analysis (or within nine months from the time EPA completes its review of the modeling protocol).
• By February 1, 2002—The State will provide EPA with a summary of its modeling analysis.
• By August 1, 2003—The State will complete a SIP revision to resolve the increment issue (if the modeling analysis shows that the increment is exceeded).

Note that EPA is publishing the State's commitments in order to inform the public of the process that the State and EPA are following to address the increment violations modeled by the State. However, this document does not make the State's commitments legally binding.

EPA responded to the State in a letter dated March 28, 2001. Specifically, EPA stated that, in light of the State's March 13, 2001 commitment letter, we will not initiate formal action to call for a SIP revision to address these violations of the PSD increments for SO₂. We acknowledged that the State needs to refine the modeling analysis to better determine the appropriate control strategy(ies) to address the violations, and we will work with the State in its efforts. If the State does not meet its commitments, or if the State and EPA cannot agree on an acceptable modeling protocol or on acceptable control measures, we may decide to initiate a formal SIP call.

II. What Are the PSD Increments?

The purpose of the PSD program of the Clean Air Act (Act), 42 U.S.C. 7470-7479, is to ensure that the air quality in clean air areas remains clean and does not deteriorate to the level of the national ambient air quality standards (NAAQS). The mechanism created by Congress to meet this goal is the establishment of “PSD increments.” These increments define the maximum allowable increases over baseline concentrations that are allowed in a clean air area for a particular pollutant. Any increase above this level indicates that significant deterioration of air quality has occurred. Because only emissions increases above the baseline concentration are considered in determining how much increment has been consumed, the amount of increment consumed can only be determined through air quality dispersion modeling, not through direct monitoring of ambient concentrations.

The Act provides for three different classes of air quality protection, to reflect varying levels of protection from significant deterioration in air quality. In the 1977 Clean Air Act Amendments, Congress designated all international parks, national wilderness areas and national memorial parks which exceed 5000 acres in size, and all national parks which exceed 6000 acres in size as mandatory Class I areas. Congress also allowed States or Tribes to request redesignation of any area to Class I air quality protection status. Class I areas are to receive special protection from degradation of air quality, and the most stringent PSD increments apply in these areas.

The Class I increments for SO₂ are defined in section 163(b)(1) of the Act, 42 U.S.C. 7473(b)(1), as follows:

These increments are also promulgated in EPA's PSD regulations at 40 CFR 52.21(c). North Dakota has adopted these increments as state regulation in section 33-15-15-01.2.b. of the North Dakota Administrative Code, which EPA approved as part of the SIP on November 2, 1979 (44 FR 63102).

For any averaging period other than an annual averaging period, section 163(a) of the Act allows the increment to be exceeded during one such period per year. Otherwise, section 163 of the Act provides that the increments are not to be exceeded and that the SIP must contain measures assuring that the increments will not be exceeded. Section 110(a)(2)(D)(i)(II) of the Act, 42 U.S.C. 7410(a)(2)(D)(i)(II), further requires the SIP to include provisions prohibiting any source or other emitting activity within the State from emitting air pollution in amounts that will interfere with measures to be included in any other State's implementation plan to prevent significant deterioration of air quality. EPA's PSD regulations also provide that the SIP must be revised whenever EPA or the State determines that an applicable PSD increment is being violated. (See 40 CFR 51.166(a)(3).)

III. How Can I Obtain More Information on This Matter?

Copies of the State's March 13, 2001 letter and EPA's March 28, 2001 response can be obtained from the contact person listed above. A Background Document is also available, which discusses in greater detail the PSD requirements of the Act, the history of PSD increment violations in North Dakota Class I areas, and the State's draft modeling analysis.

This notice today informs the public and identifies the appropriate EPA regional office from which the public may gain further information and review the relevant documents pertaining to this North Dakota PSD increment issue.