[Federal Register Volume 68, Number 100 (Friday, May 23, 2003)]
[Notices]
[Pages 28211-28212]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-12181]


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ENVIRONMENTAL PROTECTION AGENCY

[ND-001-0009; FRL-7498-5]


Notice of Availability of Dispersion Modeling Analysis of PSD 
Class I Increment Consumption in North Dakota and Eastern Montana

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice of availability.

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SUMMARY: The EPA announces the availability of a dispersion modeling 
analysis of Prevention of Significant Deterioration (PSD) increment 
consumption in North Dakota and eastern Montana. EPA's air quality 
modeling analysis is contained in a report titled Dispersion Modeling 
Analysis of PSD Class I Increment Consumption in North Dakota and 
Eastern Montana (May 2003 Version). The results of this analysis show 
numerous violations of the Class I PSD increments for sulfur dioxide 
(SO2) in four Class I areas. These Class I areas are the 
Theodore Roosevelt National Park and the Lostwood Wilderness Area in 
North Dakota and the Medicine Lakes Wilderness Area and Fort Peck 
Indian Reservation in Montana. The EPA is soliciting additional public 
comments on this analysis before taking any further actions.

DATES: Comments on the May 2003 version of the Report will be accepted 
for 30 days. Comments must be received in writing on or before June 23, 
2003.

ADDRESSES: Written comments may be mailed to Richard R. Long, Director, 
Air and Radiation Program, Mailcode 8P-AR, Environmental Protection 
Agency (EPA), Region VIII, 999 18th Street, Suite 300, Denver, Colorado 
80202. The Report and supporting documentation

[[Page 28212]]

are available on EPA's Web site at http://www.epa.gov/region8/air/ndair.html. Copies of the Report and supporting documentation and data 
are also 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. 
Interested persons should contact the person listed below to arrange a 
time to view the Report.

FOR FURTHER INFORMATION CONTACT: Carl Daly, EPA, Region VIII, (303) 
312-6416.

SUPPLEMENTARY INFORMATION: 

I. What Are the PSD Increments?

    The purpose of the Prevention of Significant Deterioration (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:

Annual arithmetic mean--2 [mu]g/m\3\
Twenty-four hour maximum--5 [mu]g/m\3\
Three-hour maximum--25 [mu]g/m\3\

    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 State 
Implementation Plan (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).)

II. What Is the Basis for EPA's Modeling Study and What Are the Next 
Steps?

    The North Dakota Department of Health (NDDH) conducted a modeling 
analysis in 1999 and prepared a draft report that showed violations of 
the Class I PSD increments for SO2 in four Class I areas. In 
a March 13, 2001 letter to EPA, the NDDH 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 (see EPA's May 29, 
2001 Information Notice for more details, 66 FR 29127). However, in 
developing a modeling approach to finalize the study, EPA and North 
Dakota could not fully agree on the appropriate data, or the emissions 
inputs that should be used in the final modeling. Therefore, EPA 
prepared a dispersion modeling analysis of PSD increment consumption in 
North Dakota and eastern Montana. On March 5, 2002 EPA released a draft 
analysis report (January 2002 Version) to interested stakeholders for 
review and comment. The draft modeling results showed numerous 
violations of the PSD increment for SO2, both for the three-
hour and twenty-four hour increments, in four Class I areas. Comments 
received on the January 2002 draft Report have been considered by EPA 
and incorporated as appropriate into this May 2003 version of the 
Dispersion Modeling Analysis of PSD Class I Increment Consumption in 
North Dakota and Eastern Montana Report. These public comments and the 
January 2002 draft Report are available for review on the Web site 
noted below.
    As outlined in the May 2003 version Report, EPA's methodology 
follows EPA regulatory requirements and guidance as applied over the 
last 20 plus years. We believe this approach also best meets the intent 
of the increment modeling--to characterize the potential for increment 
violations under realistic emissions and meteorology conditions.
    The results of this study are similar to those from the air quality 
modeling analysis completed by the State of North Dakota in 1999 and 
from EPA's January 2002 draft Report. EPA will consider all comments 
received before taking any further actions.

III. How Can I Obtain a Copy of and/or Provide Input on This Report?

    The May 2003 version of the Report and supporting documentation are 
available on EPA's Web site at http://www.epa.gov/region8/air/ndair.html. Copies of the Report can also be obtained from the contact 
person listed above. Written comments may be mailed to Richard R. Long, 
Director, Air and Radiation Program, Mailcode 8P-AR, Environmental 
Protection Agency (EPA), Region VIII, 999 18th Street, Suite 300, 
Denver, Colorado 80202.
    This notice today informs the public and identifies the appropriate 
EPA regional office from which the public may gain further information 
and view the Dispersion Modeling Analysis of PSD Class I Increment 
Consumption in North Dakota and Eastern Montana Report (May 2003 
Version). This notice and the May 2003 version of the Report do not 
constitute final agency action. Such action may be taken at some point 
in the future, after notice and comment, as may be necessary to address 
any PSD increment violations.

    Dated: May 2, 2003.
Robert E. Roberts,
Regional Administrator, Region VIII.
[FR Doc. 03-12181 Filed 5-22-03; 8:45 am]
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