[Federal Register Volume 60, Number 56 (Thursday, March 23, 1995)]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-6926]
ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 52
Transportation Conformity; Proposed Approval of Petition for
Exemption From Nitrogen Oxides Provisions, Colorado
AGENCY: Environmental Protection Agency.
ACTION: Proposed rule.
SUMMARY: The Environmental Protection Agency (EPA) is proposing to
approve a petition that was submitted pursuant to section 182(f) of the
Clean Air Act (as amended in 1990) (CAA) by the Denver Regional Council
of Governments (DRCOG) requesting that the Denver metropolitan area, an
ozone nonattainment area classified as transitional, be exempted from
the requirements regarding the control of oxides of nitrogen (NOX)
imposed by the Federal conformity rules. These rules waive certain
NOX requirements if an exemption under section 182(f) is granted
by EPA. The EPA has indicated in relevant guidance that areas
(including transitional areas, like the Denver Metropolitan area)
demonstrating attainment based on ambient air quality monitoring data
without additional NOX reductions satisfy the exemption test.
DATES: Comments must be received on or before April 24, 1995.
ADDRESSES: Written comments should be addressed to: Douglas M. Skie,
Chief, Air Quality Branch (8ART-AP), United States Environmental
Protection Agency, Region VIII, 999 18th Street, suite 500, Denver,
Copies of the DRCOG petition and other information relevant to this
action are available for inspection between 8 a.m. and 4 p.m. Monday
through Friday at the following locations: United States Environmental
Protection Agency, Region VIII, Air Quality Branch (8ART-AP), 999 18th
Street, suite 500, Denver, Colorado 80202-2466.
Air and Radiation Docket and Information Center, United States
Environmental Protection Agency, 401 M. Street SW., Washington, DC
Anyone wishing to review this petition at the Denver EPA Regional
office is asked to contact the person below to schedule an appointment
24 hours in advance.
FOR FURTHER INFORMATION CONTACT: Ms. Aundrey C. Wilkins, SIP Section
(8ART-AP), Air Programs Branch, United States Environmental Protection
Agency, Region VIII, 999 18th Street, Suite 500, Denver, Colorado,
80202-2466, telephone (303) 294-1379.
Section 182(f) of the Clean Air Act contains requirements for major
stationary NOX sources in marginal and above ozone nonattainment
areas and in an ozone transport region. Section 182(f) also specifies
circumstances under which the NOX requirements would be limited or
would not apply.
Under section 182(f)(1)(A), an exemption from the NOX
requirements may be granted for nonattainment areas outside an ozone
transport region if EPA determines that ``additional reductions of
NOX would not contribute to attainment'' of the ozone NAAQS in
those areas. EPA has indicated that in cases where a nonattainment area
is demonstrating attainment with 3 consecutive years of air quality
monitoring data, without having implemented the section 182(f) NOX
provisions, it is clear that this test is met since ``additional
reductions of NOX would not contribute to attainment'' of the
NAAQS in that area.
EPA's general and transportation conformity rules reference the
section 182(f) exemption process as a means for exempting affected
areas from certain NOX conformity requirements. See 58 FR 62197,
November 24, 1993, Transportation Conformity, and 58 FR 63240, November
30, 1993, General Conformity.
This interpretation is discussed in a May 27, 1994 memorandum from
John S. Seitz, Director, Office of Air Quality Planning and Standards
(OAQPS), entitled ``Section 182(f) Nitrogen Oxides (NOX)
Exemptions--Revised Process and Criteria.'' This memorandum revised
relevant portions of previously-issued OAQPS guidance dated December,
1993, entitled ``Guideline for Determining the Applicability of
Nitrogen Oxide Requirements under Section 182(f).'' Both documents
address EPA's policy regarding NOX exemptions for areas outside an
ozone transport region that have air quality monitoring data showing
attainment. The section 182(f) NOX provisions and the guidance
cited above apply to marginal and above ozone nonattainment areas, but
not nonclassifiable ozone nonattainment areas (i.e., submarginal,
transitional, and incomplete/no data). However, on June 17, 1994, EPA
published a document entitled ``Conformity; General Preamble for
Exemption from Nitrogen Oxides Provisions'' (59 FR 31238) (``General
Preamble''). This document provides guidance on the exemption of
nonclassifiable ozone nonattainment areas, outside an ozone transport
region, from the conformity rule's NOX provisions based on air
quality monitoring data showing attainment. As a transitional ozone
nonattainment area, the Denver metropolitan area falls within the
Pursuant to section 182(f), a person or State may petition EPA to
grant an exemption which would relieve the relevant nonattainment area
from certain requirements of the general and transportation conformity
rule. DRCOG submitted a NOX exemption petition on May 25, 1994 and
submitted supporting documentation via a letter dated August 1, 1994.
Ambient air quality data provided with the DRCOG petition showed no
violations of the ozone NAAQS during the three-year period from 1991
through 1993. Further, the Colorado Air Pollution Control Division
(APCD) provided additional air quality data for the same time period
supporting DRCOG's position that there were no violations.
II. Analysis of the DRCOG Petition for a NOX Exemption
EPA believes that DRCOG has demonstrated that the Denver
metropolitan area qualifies for an exemption from the NOX
conformity requirements based on the ambient data provided by DRCOG and
APCD for 1991, 1992, and 1993. The AIRS data show no violations of
ozone NAAQS during these three years.
The APCD has endorsed the DRCOG petition in a letter dated December
15, 1994, from Tom Getz, Director, APCD, to Mr. William Yellowtail, the
EPA Region VIII Regional Administrator.
III. Analysis of Other Ozone Network Issues
EPA considered the condition of the ozone ambient air monitoring
network as part of evaluating the DRCOG NOX exemption request. In
1989, EPA called attention to suspected deficiencies in the ozone
ambient air monitoring network. EPA and the APCD have continued to
address these concerns over the years. The APCD conducted studies of
the ozone network in 1991 and 1992. A 1993 study report noted that the
network was not measuring at maximum concentrations. The APCD found
that the maximum concentration area covered the northwest and southwest
parts of the ozone nonattainment area. The state is required to
designate at least one site, but should include as many as are
necessary, to adequately monitor the maximum concentration area. (40
CFR Part 58).
In 1993, it was determined that higher values appeared in the
northwest part of [[Page 15270]] the maximum concentration area rather
than in the southwest. Priority was given to placing new sites in the
In 1993, APCD added two new sites in the northwest--Enrel and South
Boulder Creek. No violations were recorded at these two sites in 1993.
However, data in AIRS show one exceedance at the South Boulder Creek
site in 1993. Three exceedances must occur for there to be a violation.
These two new sites were retained and studied in 1994. The APCD has
reported that no violations or exceedances occurred at either of these
sites in 1994.
There are nine sites currently on the Denver ozone ambient air
monitoring network, including the two new sites. The Enrel and South
Boulder Creek sites continue to record higher values than other sites
on the network. The one exceedance at the South Boulder Creek site in
1993 and the continued higher value readings at the same site and at
the Enrel site confirm study findings that these sites are within the
maximum concentration area and should remain in place.
Modifying the network to ensure monitoring of maximum
concentrations is an EPA priority and is required by 40 CFR part 58.
The EPA is working with APCD to ensure that at least one monitoring
site is established in the southwest area in 1995. In addition, the
APCD plans to conduct further study in this southwest area during the
1995 summer ozone season to more accurately identify where sites should
Although there have been concerns with the monitoring network, EPA
believes that many of the concerns have been corrected and that any
remaining concerns are not significant enough to deny the NOX
waiver. As indicated above, no violations have been recorded by the
network, even since installation of the Enrel and South Boulder Creek
sites in 1993. In addition, the NOX waiver policy published in the
General Preamble provides further protection by providing for granting
a NOX exemption on a contingent basis as described in section IV
of this Federal Register document. This allows EPA to revoke the
exemption if violations are recorded at any monitoring sites.
IV. Approval of the NOX Exemption on a Contingent Basis
According to the General Preamble, approval of an exemption based
solely on ambient air quality monitoring data shall be granted on a
contingent basis, i.e., the exemptions will last for only as long as
the area's monitoring data continue to demonstrate attainment. If EPA
subsequently determines that the area has violated the ozone standard,
the exemption, as of the date of the determination, will no longer
apply. If a violation of the ozone NAAQS is monitored in the Denver
Metropolitan Area, EPA will provide notice in the Federal Register.
Existing transportation plans and TIPs and past conformity
determinations will not be affected by a determination that the
NOX exemption no longer applies, but new conformity determinations
would have to observe the NOX requirements of the conformity rule.
The State must continue to operate an appropriate ambient air quality
monitoring network, in accordance with 40 CFR Part 58, to verify the
attainment status of the area. The air quality data relied on for the
above determination must be consistent with 40 CFR part 58 requirements
and other relevant EPA guidance, and recorded in EPA's AIRS national
The EPA NOX exemption guidelines, published in the General
Preamble, do not require that a redesignation request be submitted with
a request for a NOX transportation conformity exemption.
Conditional exemptions from the transportation conformity NOX
requirements do not substitute for the redesignation process.
The General Preamble stated that for areas which are relying on
monitoring data for the exemption request, the notice proposing
approval of the exemption request should provide opportunity for
comment on the preliminary interpretations contained in the General
Preamble. It should also offer opportunity for comment on the
appropriateness of using monitoring data which are consistent with the
requirements in 40 CFR part 58 and are recorded in AIRS as the basis of
EPA's approval and rescission of the contingent NOX exemption.
Accordingly, EPA requests comments regarding these matters.
V. Impacts of Granting a NOX Waiver for Denver Metropolitan
In ozone nonattainment areas classified as transitional, such as
the Denver metropolitan area, the effect of a NOX exemption is
limited solely to the issue of whether such areas may be exempted from
meeting the applicable NOX requirements of the transportation and
general conformity rule.
EPA also stated in the General Preamble that it plans to amend the
transportation conformity rule to require that once an area's
maintenance plan is approved, any previously approved NOX
conformity exemption no longer applies. The area must then demonstrate
as part of its conformity determinations that the transportation plan
and TIP are consistent with the motor vehicle emissions budgets for
NOX where such a budget is established by the maintenance plan. As
currently written, none of the transportation conformity rule's
NOX requirements would ever apply to an area once such an area had
received a NOX transportation conformity exemption.
Under the Regulatory Flexibility Act, 5 U.S.C. 600 et seq., EPA
must prepare a regulatory flexibility analysis assessing the impact of
any proposed or final rule on small entities. (5 U.S.C. 603 and 604).
Alternatively, EPA may certify that the rule will not have a
significant impact on a substantial number of small entities. Small
entities include small businesses, small not-for-profit enterprises,
and government entities with jurisdiction over populations of less than
This proposal does not create any new requirements. Therefore, I
certify that it does not have significant impact on any small entities
affected. Moreover, due to the nature of the federal-state relationship
under the CAA, preparation of a regulatory flexibility analysis would
constitute federal inquiry into the economic reasonableness of state
The OMB has exempted these actions from review under Executive
Interested parties are invited to comment on all aspects of this
List of Subjects in 40 CFR Part 52
Environmental protection, Air pollution control, Carbon Monoxide,
Hydrocarbons, Intergovernmental relations, Lead, Nitrogen dioxide,
Ozone, Particulate matter, Reporting and recordkeeping requirements,
Volatile organic compounds.
Authority: 42 U.S.C. 7401-7671q.
Dated: March 10, 1995.
William P. Yellowtail,
[FR Doc. 95-6926 Filed 3-22-95; 8:45 am]
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