[Federal Register Volume 59, Number 120 (Thursday, June 23, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-15305]


[[Page Unknown]]

[Federal Register: June 23, 1994]


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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Parts 52 and 81
[CO29-1-6414, CO29-1-6415, & CO36-5-6405; FRL-5003-1]

 

Clean Air Act Approval and Promulgation of PM10 
Implementation Plan for Colorado

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: EPA proposes partial approval of the State implementation plan 
(SIP) submitted by the State of Colorado to achieve attainment of the 
National Ambient Air Quality Standards (NAAQS) for particulate matter 
with an aerodynamic diameter less than or equal to a nominal 10 
micrometers (PM10), including: control measures, technical 
analyses, and other Clean Air Act SIP requirements, with the exception 
of the quantitative milestones element. The SIP was submitted by the 
Governor of Colorado in a letter dated March 17, 1993 to satisfy 
certain federal requirements for an approvable SIP for the Telluride, 
Colorado moderate PM10 nonattainment area. EPA proposes 
conditional approval of the quantitative milestone element because the 
SIP does not demonstrate maintenance of the PM10 NAAQS through 
1997. However, the State has committed to adopt control measures 
necessary to provide for maintenance.
    In addition, EPA proposes full approval of the SIP revision 
submitted by the Governor with a letter dated December 9, 1993 to 
address contingency measure requirements for the Telluride moderate 
PM10 nonattainment area.
    Finally, EPA is proposing to amend the boundary for the Telluride 
nonattainment area to clarify the original description.

DATES: Comments on this proposed action must be received in writing by 
July 25, 1994.

ADDRESSES: Comments should be addressed to Amy Platt, Air Programs 
Branch, SIP Section (8ART-AP), Environmental Protection Agency, Region 
VIII, 999 18th Street, suite 500, Denver, Colorado 80202-2405.
    Copies of the State's submittals and other information are 
available for inspection during normal business hours at the following 
locations: Air Programs Branch, Environmental Protection Agency, Region 
VIII, 999 18th Street, suite 500, Denver, Colorado 80202-2405; and 
Colorado Department of Health, Air Pollution Control Division, 4300 
Cherry Creek Drive South, Denver, Colorado 80222-1530.

FOR FURTHER INFORMATION CONTACT: Amy Platt at (303) 293-1769.

SUPPLEMENTARY INFORMATION:

1. Background

    The Telluride, Colorado area was designated nonattainment for 
PM10 and classified as moderate under sections 107(d)(4)(B) and 
188(a) of the Clean Air Act, upon enactment of the Clean Air Act 
Amendments of 1990.\1\ See 56 FR 56694 (Nov. 6, 1991), 40 CFR 81.306 
(Telluride). The air quality planning requirements for moderate 
PM10 nonattainment areas are set out in subparts 1 and 4 of part 
D, title I of the Act.\2\ The EPA has issued a ``General Preamble'' 
describing EPA's preliminary views on how EPA intends to review SIPs 
and SIP revisions submitted under title I of the Act, including those 
State submittals containing moderate PM10 nonattainment area SIP 
requirements (see generally 57 FR 13498, April 16, 1992 and 57 FR 
18070, April 28, 1992). Because EPA is describing its interpretations 
here only in broad terms, the reader should refer to the General 
Preamble for a more detailed discussion of the interpretations of title 
I advanced in this proposal and the supporting rationale. In this 
action on the Colorado moderate PM10 SIP revisions for the 
Telluride nonattainment area, EPA is proposing to apply its 
interpretations considering the specific factual issues presented. 
Thus, EPA will consider any timely submitted comments before taking 
final action on this proposal.
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    \1\The 1990 Amendments to the Clean Air Act made significant 
changes to the Act. See Public Law No. 101-549, 104 Stat. 2399. 
References herein are to the Clean Air Act, as amended (``the 
Act''). The Clean Air Act is codified, as amended, in the U.S. Code 
at 42 U.S.C. 7401, et seq.
    \2\Subpart 1 contains provisions applicable to nonattainment 
areas generally and Subpart 4 contains provisions specifically 
applicable to PM10 nonattainment areas. At times, Subpart 1 and 
Subpart 4 overlap or conflict. EPA has attempted to clarify the 
relationship among these provisions in the ``General Preamble'' and, 
as appropriate, in today's notice and supporting information.
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    Those States containing initial moderate PM10 nonattainment 
areas (those areas designated under section 107(d)(4)(B) of the Act) 
were required to submit, among other things, the following provisions 
by November 15, 1991:
    1. Provisions to assure that reasonably available control measures 
(RACM) [including such reductions in emissions from existing sources in 
the area as may be obtained through the adoption, at a minimum, of 
reasonably available control technology (RACT)] shall be implemented no 
later than December 10, 1993;
    2. Either a demonstration (including air quality modelling) that 
the plan will provide for attainment as expeditiously as practicable 
but no later than December 31, 1994, or a demonstration that attainment 
by that date is impracticable;
    3. Quantitative milestones which are to be achieved every three 
years and which demonstrate reasonable further progress (RFP) toward 
attainment by December 31, 1994; and
    4. Provisions to assure that the control requirements applicable to 
major stationary sources of PM10 also apply to major stationary 
sources of PM10 precursors except where the Administrator 
determines that such sources do not contribute significantly to 
PM10 levels which exceed the NAAQS in the area. See sections 
172(c), 188, and 189 of the Act.
    Some provisions were due at a later date. States with initial 
moderate PM10 nonattainment areas were required to submit a permit 
program for the construction and operation of new and modified major 
stationary sources of PM10 by June 30, 1992 (see section 189(a)). 
EPA will address this requirement, as appropriate, in a future action. 
Such States also were required to submit contingency measures by 
November 15, 1993 which become effective without further action by the 
State or EPA, upon a determination by EPA that the area has failed to 
achieve reasonable further progress or to attain the PM10 NAAQS by 
the applicable statutory deadline (see section 172(c)(9) and 57 FR 
13543-13544). The State of Colorado has submitted contingency measures 
for Telluride and EPA is addressing those measures in this notice.

I. This Action

    Section 110(k) of the Act sets out provisions governing EPA's 
review of SIP submittals (see 57 FR 13565-13566). EPA is proposing 
partial approval of those elements (excluding the quantitative 
milestones element) of the Telluride PM10 SIP, which were due on 
November 15, 1991 and submitted on March 17, 1993. Further, section 
110(k)(4) of the Act authorizes EPA to approve a plan revision based on 
a commitment of the State to adopt specific enforceable measures by a 
date certain, but not later than one year after the date of approval of 
the plan revision. EPA is proposing conditional approval of the 
quantitative milestones element of the Telluride PM10 SIP based on 
the State's commitment dated April 21, 1994 to adopt control measures 
for Telluride by November 30, 1994 that are necessary to demonstrate 
maintenance of the PM10 NAAQS. Section 110(k)(4) provides that any 
such conditional approval shall be treated as a disapproval if the 
state fails to comply with such commitment.\3\
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    \3\If the State fails to comply with its commitment, this 
conditional approval of the quantitative milestones element will 
become a disapproval upon EPA notification of the State by letter. 
EPA subsequently will publish a notice in the ``Notices Section'' of 
the Federal Register announcing such action and explaining its 
implications. If EPA determines that it cannot issue a final 
conditional approval of the quantitative milestones element of the 
SIP or if the conditional approval is converted to a disapproval, 
the sanctions clock under section 179(a) of the Act will begin. This 
clock will begin at the time EPA issues a final disapproval or at 
the time EPA notifies the State by letter that a conditional 
approval has been converted to a disapproval.
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    Although the State did not follow EPA guidance in calculating its 
original attainment and maintenance demonstrations provided in the SIP, 
it included a commitment to revise the demonstrations consistent with 
EPA guidance (based on a revised emissions inventory and chemical mass 
balance (CMB) analysis). These analyses have been completed.
    The revised analyses were received from the State in a September 
20, 1993 letter from Thomas Getz, Colorado Air Pollution Control 
Division (APCD) to Douglas Skie, EPA. The revised demonstration, 
calculated consistent with EPA guidance, corroborates the attainment 
demonstration provided in the SIP, i.e., it still shows attainment of 
the PM10 NAAQS by December 31, 1994. However, the revised 
demonstration does not show maintenance of the PM10 NAAQS through 
1997 as called for by the quantitative milestones requirement. Although 
the area has not recorded a violation of the PM10 NAAQS since 
1986, projections indicate that Telluride's extensive growth rate will 
cause the area to fall out of attainment after the end of 1994. Section 
189(c) of the Act provides that moderate area SIP revisions must 
contain quantitative milestones which are to be achieved every three 
years until the nonattainment area is redesignated attainment and which 
demonstrate reasonable further progress toward attainment. As explained 
further in part II.A.6 below, at least two three-year milestones 
(showing, at a minimum, continued maintenance of the NAAQS through 
1997) were to be submitted with the moderate area SIP for Telluride due 
on November 1991.
    The quantitative milestone element of the Telluride SIP is 
deficient in that it does not demonstrate that the second quantitative 
milestone--continued maintenance from 1994 through 1997--will be 
achieved. EPA proposes to conditionally approve this element of the SIP 
in light of the State's commitment to adopt additional control measures 
necessary to provide for continued maintenance.
    The State has indicated that it intends to address the maintenance 
issue by proposing for adoption additional control measures to maintain 
the PM10 NAAQS through 1997. In an April 21, 1994 letter from 
Thomas Getz, APCD, to Douglas Skie, EPA, the State made the following 
commitments. Maintenance control measures and any related SIP revision 
will be proposed to the Colorado Air Quality Control Commission (AQCC) 
by July 21, 1994. A public hearing on such regulations and SIP revision 
will be held by October 20, 1994 and the adopted regulations and SIP 
revision will be submitted to EPA by November 30, 1994. The effective 
date of such measures must be November 1, 1995, but could be as early 
as December 1, 1994.
    While the State has allowed some of its commitment dates to slip in 
the past due to numerous SIP development activities, EPA believes these 
dates are achievable for the following reasons. Most of the initial SIP 
development work for the State's PM10 nonattainment areas has been 
completed, thus lessening some of the competing demands on its 
workload. Further, the local Telluride governments and citizens appear 
to be dedicated to improving their air quality and supportive of 
efforts to move forward with maintenance measures.
    Upon adoption and submittal to EPA, these additional control 
measures for maintenance will be evaluated for their adequacy in 
allowing the area to demonstrate maintenance through 1997.
    Because of the quantitative milestones deficiency, EPA is proposing 
to grant partial approval of the remaining elements of the Telluride 
PM10 plan that were due on November 15, 1991, and submitted by the 
State on March 17, 1993. Further, EPA proposes full approval of the 
contingency measures submitted by the State on December 9, 1993. EPA 
believes that the Telluride plan meets those applicable requirements of 
the Act. EPA proposes conditional approval of the quantitative 
milestones element. While the SIP does not demonstrate that maintenance 
of the NAAQS will be achieved through 1997, the State has committed to 
adopt by November 30, 1994 the necessary control measures to provide 
for maintenance.
    In addition, EPA is proposing to amend the nonattainment area 
boundary description for Telluride in order to clarify the original 
description.
    Since the Telluride PM10 SIP elements due on November 15, 1991 
were not submitted by that date, as required by section 189(a)(2)(A) of 
the Act, EPA made a finding that the State failed to submit the SIP, 
pursuant to section 179 of the Act, and notified the Governor in a 
letter dated December 16, 1991. See 57 FR 19906, 19908 (May 8, 1992). 
After the Telluride PM10 SIP was submitted on March 17, 1993, EPA 
found the submittal complete pursuant to section 110(k)(1) of the Act 
and notified the Governor accordingly in a letter dated April 30, 1993. 
This completeness determination corrected the State's deficiency and 
turned off the sanctions clock under section 179 of the Act.

A. Analysis of State Submission

1. Procedural Background
    The Act requires States to observe certain procedural requirements 
in developing implementation plans and plan revisions for submission to 
EPA. Section 110(a)(2) of the Act provides that each implementation 
plan submitted by a State must be adopted after reasonable notice and 
public hearing.4 Section 110(l) of the Act similarly provides that 
each revision to an implementation plan submitted by a State under the 
Act must be adopted by such State after reasonable notice and public 
hearing.
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    \4\Also section 172(c)(7) of the Act requires that plan 
provisions for nonattainment areas meet the applicable provisions of 
section 110(a)(2).
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    EPA also must determine whether a submittal is complete and 
therefore warrants further EPA review and action (see section 110(k)(1) 
and 57 FR 13565). EPA's completeness criteria for SIP submittals are 
set out at 40 CFR part 51, appendix V (1992). The EPA attempts to make 
completeness determinations within 60 days of receiving a submission. 
However, a submittal is deemed complete by operation of law if a 
completeness determination is not made by EPA six months after receipt 
of the submission.
    To entertain public comment on the PM10 implementation plan 
requirements for Telluride due on November 15, 1991, the Town of 
Telluride, after providing adequate notice, held a public meeting on 
September 24, 1992, and the State of Colorado held a public hearing on 
January 21, 1993 to address the Telluride PM10 SIP. Following the 
public hearings, the Telluride PM10 SIP was adopted by the State. 
The Telluride PM10 SIP was submitted to EPA by the Governor in a 
letter dated March 17, 1993.
    In a letter to the State dated May 14, 1993, EPA requested 
additional information to determine the approvability of the Telluride 
SIP. This information, as submitted by the State in a letter dated June 
8, 1993, adequately addressed EPA's concerns.
    The Telluride PM10 SIP was reviewed by EPA to determine 
completeness in accordance with the completeness criteria set out at 40 
CFR part 51, appendix V. The submittal was found to be complete and a 
letter dated April 30, 1993 was forwarded to the Governor indicating 
the completeness of the submittal and the next steps to be taken in the 
review process.
    To entertain public comment on the PM10 contingency measures 
for Telluride, the State of Colorado, after providing adequate notice, 
held a public meeting on November 12, 1993. Following the public 
hearings, the Telluride PM10 contingency measures were adopted by 
the State. A revision to the Telluride PM10 SIP to include the 
contingency measures was submitted to EPA by the Governor in a letter 
dated December 9, 1993. The submittal was found to be complete by EPA, 
and the Governor was so notified in a February 15, 1994 letter.
    EPA proposes partial approval of those elements (excluding the 
quantitative milestones element) of the Colorado PM10 SIP 
submittal for Telluride that were due on November 15, 1991 and 
conditional approval of the quantitative milestones requirement. EPA 
proposes full approval of the PM10 contingency measures for the 
Telluride area. Finally, EPA is proposing to replace the boundary 
description currently in 40 CFR 81.306 with a revised description to 
more clearly define the nonattainment area. Public comment is invited 
on all these actions.
2. Accurate Emissions Inventory
    Section 172(c)(3) of the Act requires that nonattainment plan 
provisions include a comprehensive, accurate, current inventory of 
actual emissions from all sources of relevant pollutants in the 
nonattainment area. The emissions inventory also should include a 
comprehensive, accurate, and current inventory of allowable emissions 
in the area. See, for example, section 110(a)(2)(K). Because the 
submission of such inventories is a necessary adjunct to an area's 
attainment demonstration (or demonstration that the area cannot 
practicably attain), the emissions inventories must be received with 
the demonstration submission (see 57 FR 13539).
    The APCD chose 1991 as the Telluride base year emissions inventory 
of actual PM10 emissions. The results were as follows. Area 
sources contribute to approximately 96 percent of the total emissions 
for the area, with geologic material (including re-entrained road dust 
from highways, paved roads, chip sealed roads, and unpaved roads) 
contributing approximately 82 percent, wood burning contributing 
approximately 13 percent, and tailpipe emissions contributing 
approximately one percent. The remaining four percent of PM10 
emissions is due to point sources.
    The emissions inventory demonstrates that re-entrained road dust 
and wood burning are the major sources of PM10 emissions. Point 
sources are responsible for only a small percentage of the PM10 
emissions in the Telluride nonattainment area.
    The emissions inventory was generally calculated using EPA's 
``Compilation of Air Pollution Emission Factors (AP-42)'' with the 
exception of the sanding emissions, which were calculated using 
emission factors developed for the Denver PM10 SIP at EPA's 
recommendation. EPA had previously commented that the AP-42 default 
emission factors for re-entrained road dust likely underestimated 
emissions from re-entrained road dust for high elevation mountain 
towns, such as Telluride. The State, therefore, included a commitment 
in the Telluride SIP to conduct a silt loading study in Telluride 
during the winter of 1992-1993 and to use that study to improve the 
emissions inventory and verify the adequacy of the attainment and 
maintenance demonstrations. This commitment has been completed, and the 
State used the revised emissions inventory correctly to recalculate the 
attainment and maintenance demonstrations. The revised emissions 
inventory indicates a slightly higher contribution from area sources, 
due to an increase in the estimated contribution from re-entrained road 
dust. See Section II.A.4. below and the Technical Support Document 
(TSD) for further information.
    Since the emissions inventory was calculated using EPA's AP-42 
(with the exception of the sanding emissions, as noted above), EPA is 
proposing to approve the emissions inventory because it generally 
appears to be accurate and comprehensive, and provides a sufficient 
basis for determining the adequacy of the attainment demonstration for 
this area consistent with the requirements of sections 172(c)(3) and 
110(a)(2)(K) of the Act.5 For further details see the TSD for this 
action.
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    \5\EPA issued guidance on PM-10 emissions inventories prior to 
the enactment of the Clean Air Act Amendments in the form of the 
1987 PM-10 SIP Development Guideline. The guidance provided in this 
document appears to be consistent with the amended Act. See section 
193 of the Act.
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3. RACM (Including RACT)
    As noted, the initial moderate PM10 nonattainment areas must submit 
provisions to assure that RACM (including RACT) are implemented no 
later than December 10, 1993 (see sections 172(c)(1) and 189(a)(1)(C)). 
The General Preamble contains a detailed discussion of EPA's 
interpretation of the RACM (including RACT) requirement (see 57 FR 
13539-13545 and 13560-13561).
    In broad terms, the State should identify available control 
measures and evaluate them for their reasonableness in light of the 
feasibility of the controls and the attainment needs of the area. 57 FR 
13540-13544. A State may reject an available control measure if the 
measure is technologically infeasible or the cost of the control is 
unreasonable. In addition, RACM does not require controls on emissions 
from sources that are insignificant (i.e., de minimis) and does not 
require the implementation of all available control measures where an 
area demonstrates timely attainment and the implementation of 
additional controls would not expedite attainment.
    Colorado's SIP revision for Telluride contains control measures for 
sources of wood and coal burning. In the following table, an outline is 
presented on the control measure, associated emissions reduction 
credit, and effective date.

----------------------------------------------------------------------------------------------------------------
      Source category               Control measure            PM10 emissions reduction        Effective date   
----------------------------------------------------------------------------------------------------------------
Wood and coal burning.....  Colorado regulation entitled    ..............................  March 2, 1993.      
                             ``State Implementation Plan-                                                       
                             Specific Regulations for                                                           
                             Local Elements, Telluride                                                          
                             Nonattainment Area''.                                                              
                            Requires continued              Existing local programs were                        
                             implementation of local         given emission reduction                           
                             programs to control solid       credits in the base,                               
                             fuel burning devices,           attainment, and maintenance                        
                             eliminate coal burning, &       year emissions inventories.                        
                             prohibit installation of                                                           
                             additional solid fuel burning                                                      
                             devices.                                                                           
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    Since 1986, no violations of the PM10 NAAQS have been recorded 
in Telluride. RACM does not require additional controls on other area 
sources since the plan demonstrates attainment of the NAAQS and 
implementation of additional controls would not further expedite 
attainment. Further, RACT does not require additional controls for the 
stationary sources in the Telluride nonattainment area because point 
source emissions in the area are de minimis and control of such sources 
would not expedite attainment of the PM10 NAAQS.
    There are also other Statewide control measures that already apply 
in the Telluride area, which will help curb PM10 emissions in the 
Telluride nonattainment area. Specifically, Colorado Regulation No. 4 
requires new wood stoves to meet the emission requirements of EPA's 
Standards of Performance for New Residential Wood Heaters in 40 CFR 
60.532(b), and Colorado Regulation No. 3 regulates the construction and 
modification of stationary sources of PM10.\6\ These measures will 
help to reduce emissions from new stationary source growth and 
residential wood combustion. However, EPA is not proposing action on 
Regulation Nos. 3 and 4 because EPA has previously approved these 
regulations in separate notices. For further information, see the TSD 
accompanying this notice.
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    \6\The State is required by the amended Clean Air Act to adopt a 
revised new source review permit program for the construction and 
operation of new and modified stationary sources. See section 
189(a)(1)(A). This SIP revision, submitted by the State on January 
14, 1993, was due independent of the November 15, 1991 moderate PM-
10 nonattainment area SIP requirements addressed in this action and 
will be addressed in a separate notice. See section 189(a)(2)(A) of 
the Act.
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    A more detailed discussion of individual source contributions, 
associated control measures (including available control technology) 
and an explanation of why certain available control measures were not 
implemented can be found in the TSD. EPA has reviewed the State's 
documentation and concluded that it adequately justifies the control 
measure to be implemented. The implementation of Colorado's PM10 
nonattainment plan for Telluride will result in the attainment of the 
PM10 NAAQS by December 31, 1994. EPA is proposing to approve the 
Telluride PM10 plan's control strategy as satisfying the RACM 
(including RACT) requirement.
4. Demonstration
    As noted, the initial moderate PM10 nonattainment areas must 
submit a demonstration (including air quality modelling) showing that 
the plan will provide for attainment as expeditiously as practicable, 
but no later than December 31, 1994, or the State must show that 
attainment by December 31, 1994 is impracticable (see section 
189(a)(1)(B) of the Act). The General Preamble sets out EPA's guidance 
on the use of modelling for PM10 moderate area attainment 
demonstrations. 57 FR 13539.
    EPA regulations provide that attainment be demonstrated by means of 
a proportional model or dispersion model or other procedure shown to be 
adequate and appropriate for such purposes. See 40 CFR 51.112(a). In 
general, EPA policy provides that the preferred approach for estimating 
the air quality impacts of emissions of PM10 is to use receptor 
modelling in combination with dispersion modelling. On July 5, 1990, 
EPA issued guidance providing that, in certain situations, it may be 
appropriate to rely on a receptor model demonstration alone as the 
basis for the attainment demonstrations (see July 5, 1990 memo to 
Regional Air Branch Chiefs from Robert D. Bauman, Chief of SO2/
Particulate Matter Programs Branch and Joseph Tikvart, Chief of Source 
Receptor Analysis Branch).
    Telluride met the criteria outlined in the July 5, 1990 memo to 
justify using receptor modelling alone and had originally planned to 
use this approach in its attainment demonstration. However, after 
further review, the State determined that the CMB data that would be 
used in the receptor modelling were inadequate and decided to base the 
attainment and maintenance demonstration on simple emissions rollback. 
Emissions rollback modelling involves using the ratio of the design day 
ambient concentration to the design day emissions and projecting future 
concentrations. However, EPA policy allows the use of other methods of 
demonstrating attainment, such as emissions rollback modelling, only in 
certain limited circumstances which were not met by this area. (See 
March 4, 1991 memorandum from John Calcagni, Director of EPA's Air 
Quality Management Division, and William G. Laxton, Director of EPA's 
Technical Support Division, entitled ``PM10 SIP Attainment 
Demonstration Policy for Initial Moderate Nonattainment Areas.'')
    The attainment demonstration presented in the March 17, 1993 
submittal indicated that the PM10 NAAQS will be attained by 1994 
in the Telluride area. The 24-hour PM10 NAAQS is 150 micrograms/
cubic meter (g/m3), and the standard is attained when the 
expected number of days per calendar year with a 24-hour average 
concentration above 150 g/m3 is equal to or less than one 
(see 40 CFR 50.6). The annual PM10 NAAQS is 50 g/m3, 
and the standard is attained when the expected annual arithmetic mean 
concentration is less than or equal to 50 g/m3 (id.).
    The demonstration for Telluride, submitted with the SIP on March 
17, 1993, indicated that the 24-hour PM10 NAAQS will be attained 
by December 31, 1994 at 119 g/m3. Because no violations 
of the PM10 annual NAAQS have been recorded in the Telluride area 
since 1986 and because the attainment demonstration submitted with the 
Telluride SIP shows attainment of the 24-hour PM10 NAAQS, EPA (in 
light of the additional analysis described below) proposes to determine 
that it is reasonable and adequate to assume that protection of the 24-
hour standard will be sufficient to protect the annual standard as 
well. The control strategies relied on to demonstrate timely attainment 
are summarized in the section above entitled ``RACM (including RACT).'' 
For a more detailed description of the attainment demonstration and the 
control strategies used, see the TSD accompanying this document.
    Because the State did not follow EPA policy in calculating the 
attainment demonstration for Telluride and because of the high growth 
rate in the Telluride area, EPA believed it was necessary for the State 
to calculate revised attainment and maintenance demonstrations in 
accordance with EPA's guidance in order to fully assess the adequacy of 
the Telluride PM10 SIP. The State has completed its revised 
demonstrations.
    Specifically, the State included a commitment in the Telluride 
PM10 SIP for the following items, which have been completed: 
conduct revised CMB analyses on all filters greater than 100 
g/m3; calculate a revised emissions inventory based on a 
silt loading study in Telluride; and use this information to assess the 
adequacy of the SIP. If necessary, a SIP revision, including any 
additional control strategies needed to demonstrate attainment and 
maintenance of the PM10 NAAQS based on the revised demonstrations, 
will be adopted by the Colorado Air Quality Control Commission (AQCC) 
and submitted to EPA.
    The revised analyses (CMB, emissions inventory, attainment and 
maintenance demonstrations), which were received from the State with a 
transmittal letter dated September 20, 1993, confirm attainment of the 
24-hour NAAQS in 1994 (at 142.7 g/m3). Therefore, EPA is 
proposing approval of the attainment demonstration. (See the TSD for 
further information.)
    However, the revised analyses do not demonstrate that the 24-hour 
PM10 NAAQS will be maintained through the November 15, 1997 second 
milestone date. In an April 21, 1994 letter from Thomas Getz, APCD, to 
Douglas Skie, EPA, the State committed to adopt additional control 
measures to demonstrate maintenance. The State's commitment included 
the following revised schedule: (a) maintenance measures will be 
proposed to the Colorado AQCC by July 21, 1994; (b) maintenance 
measures will be adopted by the Colorado AQCC by October 20, 1994; (c) 
a SIP revision including these maintenance measures will be submitted 
to EPA by November 30, 1994.
    While the State has allowed some of its commitment dates to slip in 
the past, EPA believes these dates are achievable for the following 
reasons. First, the local Telluride governments and citizens are 
dedicated to improving their air quality and supportive of efforts to 
move forward with maintenance measures. Further, some of the competing 
demands on the State's workload are reduced now that the initial SIP 
development work has been completed for the State's PM10 
nonattainment areas.
    Based on the State's commitment to adopt maintenance measures for 
Telluride, EPA proposes conditional approval of the quantitative 
milestones element of the Telluride PM10 SIP.
5. PM10 Precursors
    The control requirements that are applicable to major stationary 
sources of PM10 also apply to major stationary sources of 
PM10 precursors, unless EPA determines such sources do not 
contribute significantly to PM10 levels which exceed the NAAQS in 
that area (see section 189(e) of the Act). The General Preamble 
contains guidance addressing how EPA intends to implement section 
189(e) (57 FR 13539-13540 and 13541-13542). An analysis of air quality 
and emissions data for the Telluride nonattainment area indicates that 
exceedances of the NAAQS are attributable chiefly to direct particulate 
emissions from re-entrained road dust and residential wood burning 
(i.e., area sources). The emissions inventory for Telluride did not 
reveal any major stationary sources of PM10 precursors. 
Consequently, EPA is proposing to determine that major sources of 
precursors of PM10 do not contribute significantly to PM10 
levels in excess of the NAAQS in Telluride. The consequence of this 
proposed finding is to exclude any such sources from the applicability 
of PM10 nonattainment area control requirements. Further 
discussion of the analyses and supporting rationale for EPA's proposed 
finding are contained in the TSD accompanying this document. Note that 
while EPA is proposing to make a general finding for this area, the 
proposed finding is based on the current character of the area 
including, for example, the existing mix of sources in the area. It is 
possible, therefore, that future growth could change the significance 
of precursors in the area. EPA intends to issue future guidance 
addressing the effect of such potential changes in the significance of 
precursor emissions in an area.
6. Quantitative Milestones and Reasonable Further Progress
    The PM10 nonattainment area plan revisions demonstrating 
attainment must contain quantitative milestones which are to be 
achieved every three years until the area is redesignated attainment 
and which demonstrate RFP, as defined in section 171(1), toward 
attainment by December 31, 1994 (see section 189(c) of the Act). While 
section 189(c) plainly provides that quantitative milestones are to be 
achieved until an area is redesignated attainment, it is silent in 
indicating the starting point for counting the first three-year period 
or how many milestones must be initially addressed. In the General 
Preamble, EPA addressed the statutory gap in the starting point for 
counting the three-year milestones, indicating that it would begin from 
the due date for the applicable implementation plan revision containing 
the control measures for the area (i.e., November 15, 1991 for initial 
moderate PM10 nonattainment areas). See 57 FR 13539. As to the 
number of milestones, EPA believes that at least two milestones must be 
initially addressed. Thus, submittals to address the SIP revisions due 
on November 15, 1991 for the initial moderate PM10 nonattainment 
areas must demonstrate that two milestones will be achieved (first 
milestone: November 15, 1991 through November 15, 1994; second 
milestone: November 15, 1994 through November 15, 1997). For areas that 
demonstrate timely attainment of the PM10 NAAQS, the second 
milestone should, at a minimum, provide for continued maintenance of 
the standards.7
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    \7\Section 189(c) provides that quantitative milestones are to 
be achieved ``until the area is redesignated attainment.'' However, 
this endpoint for quantitative milestones is speculative because 
redesignation of an area as attainment is contingent upon several 
factors and future events. Therefore, EPA believes it is reasonable 
for States to initially address the first two milestones. Addressing 
two milestones will ensure that the State continues to maintain the 
NAAQS beyond the attainment date for at least some period during 
which an area could be redesignated attainment. Requiring that 
additional milestones be addressed, at least initially, would place 
a potentially unnecessary planning burden on States containing areas 
that are redesignated attainment. However, in all instances, 
additional milestones must be addressed if an area is not 
redesignated attainment.
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    For the initial PM10 nonattainment areas that demonstrate 
attainment, the emissions reduction progress made between the SIP 
submittal (due date of November 15, 1991) and the attainment date of 
December 31, 1994 (46 days beyond the November 15, 1994 milestone date) 
will satisfy the first quantitative milestone. The de minimis timing 
differential makes it administratively impracticable to require 
separate milestone and attainment demonstrations. See generally 57 FR 
13539. In implementing the quantitative milestone and RFP provisions 
for this initial moderate area, EPA has reviewed the attainment 
demonstration for the area to determine the nature of any milestones 
necessary to ensure timely attainment and whether annual incremental 
reductions should be required in order to ensure attainment of the 
PM10 NAAQS by December 31, 1994 (see section 171(1) of the Act). 
The design value for this SIP is below the PM10 NAAQS, and 
attainment is maintained through December 31, 1994, thus meeting the 
initial quantitative milestone and RFP.
    Since the Telluride PM10 SIP does not demonstrate maintenance 
of the PM10 NAAQS through November 15, 1997, the second 
quantitative milestone is not met. However, the State has committed to 
adopt measures that will provide for continued maintenance of the 
PM10 NAAQS in Telluride.
    Therefore, EPA is proposing conditional approval of the 
quantitative milestone element of the SIP submitted for the Telluride 
PM10 nonattainment area. (See Section II.A.4. for further 
information.)
7. Enforceability Issues
    All measures and other elements in the SIP must be enforceable by 
the State and EPA (see sections 172(c)(6), 110(a)(2)(A) and 57 FR 
13556). The EPA criteria addressing the enforceability of SIPs and SIP 
revisions were stated in a September 23, 1987 memorandum (with 
attachments) from J. Craig Potter, Assistant Administrator for Air and 
Radiation, et al. (see 57 FR 13541). Nonattainment area plan provisions 
also must contain a program to provide for enforcement of control 
measures and other elements in the SIP (see section 110(a)(2)(C)).
    The specific control measures contained in the SIP are addressed 
above in Section II.A.3., ``RACM (including RACT).'' The State 
regulation entitled ``State Implementation Plan--Specific Regulations 
for Local Elements, Telluride Nonattainment Area'' became effective on 
March 2, 1993. This regulation requires the Town of Telluride to 
continue implementation and enforcement of Ordinance Number 829, Series 
1988, as it existed on January 1, 1993. The State regulation also 
requires San Miguel County to continue implementation and enforcement 
of Resolutions #1986-20, #1990-33, #1992-27, as they existed on January 
1, 1993. The ordinance and resolutions will limit future growth in 
emissions from wood burning fireplaces and stoves and coal burning 
devices. Further, the State regulation includes record keeping 
requirements. The Town of Telluride and San Miguel County must each 
submit to the AQCC on a semi-annual basis beginning November 15, 1993 a 
report that describes the implementation, tracking and enforcement of 
these local control strategies. The reports must include information on 
permits, inspections, compliance, tracking, and enforcement activities 
in order to verify that the ordinances and resolutions have been 
implemented. EPA has reviewed this regulation for enforceability and 
has determined that it meets all of the criteria included in the 
September 23, 1987 Potter Memorandum.
    As discussed in Section II.A.3. above, there are also State wide 
regulations that will impact the emissions of PM10 in the 
Telluride nonattainment area. These regulations include Colorado 
Regulation No. 4, which requires all wood stoves sold after July 1, 
1991 to meet the emission requirements of EPA's Standards of 
Performance for New Residential Wood Heaters in 40 CFR 60.532(b), and 
Colorado Regulation No. 3, which requires construction permits for new 
or modified stationary sources. EPA previously reviewed these 
regulations, and determined that they met the enforceability criteria 
of the September 23, 1987 Potter Memorandum and approved them as part 
of the SIP (see the TSD for information on EPA approvals of these 
regulations).
    The State of Colorado has a program that will ensure that the 
measures contained in the SIP are adequately enforced. The Colorado 
APCD has the authority to implement and enforce all emission 
limitations and control measures adopted by the AQCC. In addition, 
Colorado statute provides that the APCD shall enforce against any 
``person'' who violates the emission control regulations of the AQCC, 
the requirements of the SIP, or the requirements of any permit. The 
definition of ``person'' includes any ``municipal corporation, county, 
city and county or other political subdivision of the State,'' such as 
the Town of Telluride and San Miguel County. Civil penalties of up to 
$15,000 per day per violation are provided for in the State statute for 
any person in violation of these requirements, and criminal penalties 
are also provided for in the State statute.
    Thus, EPA proposes to determine that the control measures contained 
in the SIP revision for Telluride are enforceable and that the APCD has 
adequate enforcement capabilities to ensure compliance with those 
control measures and the State regulations. However, when EPA receives 
those control measures the State must submit to fulfill its commitment 
to provide for continued maintenance of the PM10 NAAQS in 
Telluride, EPA will need to re-evaluate the ultimate adequacy of the 
enforcement program and the enforceability of those measures. The TSD 
contains further information on the State-wide regulations, 
enforceability requirements, and a discussion of the personnel and 
funding intended to support effective implementation of the control 
measures.
8. Contingency Measures
    As provided in section 172(c)(9) of the Act, all moderate 
nonattainment area SIPs that demonstrate attainment must include 
contingency measures. See generally 57 FR 13510-12 and 13543-44. These 
measures must be submitted by November 15, 1993 for the initial 
moderate nonattainment areas. Contingency measures should consist of 
other available measures that are not part of the area's control 
strategy. These measures must take effect without further action by the 
State or EPA, upon EPA's determination that the area has failed to make 
RFP or attain the PM10 NAAQS by the applicable statutory deadline.
    The Governor of Colorado submitted PM10 contingency measures 
for the Telluride area with a letter dated December 9, 1993. The 
measures are as follows.
    The Town Council of the Town of Telluride adopted Ordinance 972, 
Series 1992 on December 15, 1992. The ordinance requires that 0.30 
miles of dirt roads within the Town of Telluride be chip-seal paved. A 
State regulation was developed which requires that the 0.30 miles of 
unpaved dirt roads be chip-seal paved upon the determination that the 
area has failed to attain the PM10 NAAQS or make reasonable 
further progress (RFP). The emission reduction benefit from chip-
sealing the 0.30 miles of dirt roads is calculated to be 65.7 lbs. of 
PM10/day.
    The Board of Commissioners of San Miguel County adopted Resolution 
#1992-61 on October 30, 1992. This resolution requires that 2.0 miles 
of unpaved County gravel roads at the Ski Ranches Subdivision or 0.75 
miles of private dirt roads at the Hillside/Gold King Subdivision, each 
within the Telluride nonattainment area, be chip-seal paved. A State 
regulation was developed which requires that either the 2.0 or the 0.75 
miles of unpaved roads specified in the ordinance be chip-seal paved 
upon the determination that the area has failed to attain the PM10 
NAAQS or make RFP. The emission reduction benefit from chip-sealing 
0.75 miles of dirt roads at the Hillside/Gold King Subdivision is 
calculated to be 154.3 lbs. of PM10/day.
    Calculating the emission reduction benefit of chip-sealing 2.0 
miles of unpaved, gravel roads at the Telluride Ski Ranches Subdivision 
proved to be a more difficult task due to the inappropriateness for the 
Telluride area of the EPA-approved default emission factor for gravel 
roads. Both the State and EPA believe that chip-sealing an unpaved 
gravel road should result in an over-all reduction in particulate 
emissions. However, until gravel road emissions are researched and 
emission factors developed for the local Telluride area, the emission 
reduction benefit of chip-sealing 2.0 miles of unpaved, gravel roads at 
the Telluride Ski Ranches Subdivision can not be quantified.
    Both the Town of Telluride and San Miguel County have the following 
requirement. The chip-sealing must be completed prior to the end of the 
first complete paving season following EPA's determination that the 
area failed to attain the PM10 NAAQS or make RFP. EPA accepts this 
time frame due to the nature of the climate in Telluride, i.e., a 
lengthy snow season which limits the paving season to the summer 
months, and the State's imposition of several reporting requirements. 
Within 60 days following EPA's determination, a report must be 
submitted by each local government to the Colorado AQCC which describes 
the schedule for completing the chip-seal paving projects. The names 
and mileage of the streets to be paved must be identified in the 
reports. Within 60 days following the completion of the paving 
projects, a report must be submitted by each of the local governments 
to the Colorado AQCC which describes the paving activities. The names 
and mileage of the streets paved must be included in the reports. The 
TSD contains further details on these contingency measures and related 
reporting requirements.
    EPA reviewed these contingency measures and determined that they 
would adequately reduce PM10 emissions in the Telluride area 
should their implementation be necessary. Further, the State provided 
adequate documentation to demonstrate its authority in implementing and 
enforcing these measures, including how compliance will be determined 
in practice. Finally, EPA is satisfied with the State's reporting 
requirement that within 60 days of EPA's notification of failure to 
attain the NAAQS or make RFP, the local governments will provide a 
schedule and details of how the chip-sealing measures will be 
implemented.
    Therefore, EPA proposes full approval of the contingency measures 
for the Telluride moderate PM10 nonattainment area.
9. Revisions to the Nonattainment Area Boundary
    The Telluride nonattainment area boundary as codified in the 
Federal Register notice published on November 6, 1991 (see 56 FR 56736) 
is currently defined as the city limits of Telluride. See 40 CFR 
81.306. This boundary description was recommended in a submittal from 
the Governor dated August 31, 1991. In that submittal, the State 
indicated that on June 20, 1991 the AQCC adopted a map which outlined 
the Telluride PM10 nonattainment area. With its PM10 SIP 
submittal dated March 17, 1993, the State provided a clearer 
description of the boundary by providing a legal description of the map 
outline. The boundary essentially includes the Town of Telluride and 
the lower elevations along the San Miguel River downstream of town. The 
following legal description of the nonattainment area represents the 
map outline adopted by the AQCC and used by APCD for SIP purposes:
    The Telluride nonattainment area begins at the intersection of 
Colorado State Highway 145 and the Telluride service area boundary, as 
it existed in 1991. The western edge of the nonattainment area until it 
meets Remine Creek is defined as follows:
    A tract of land located in a portion of the west one-half of 
Section 28 and the east one-half of Section 29, Township 43 North, 
Range 9 west, of the New Mexico Principal Meridian, County of San 
Miguel, State of Colorado, described as follows: Beginning at the 
southwest corner of the said Section 28;

Thence N 89 deg. 36' 00'' W. 292.70 Feet;
Thence S 04 deg. 05' 12'' W. 538.63 Feet;
Thence N 03 deg. 29' 42'' W. 780.19 Feet;
Thence N 22 deg. 15' 00'' E. 3344.16 Feet;
Thence S 51 deg. 51' 49'' E. 570.44 Feet;
Thence S 03 deg. 15' 36'' E. 1106.22 Feet;
Thence S 45 deg. 24' 42'' E. 546.96 Feet;
Thence S 28 deg. 41' 12'' W. 549.62 Feet;
Thence S 29 deg. 40' 09'' E. 169.68 Feet;
Thence S 44 deg. 30' 03'' W. 649.51 Feet;
Thence S 85 deg. 54' 00'' E. 660.00 Feet;
Thence S 04 deg. 06' 00'' W. 660.00 Feet;

Thence N 89 deg. 56' 00'' E. 1318.68 Feet; to the true point of 
beginning containing 11249 acres as described above.
    Then, at Remine Creek, the nonattainment boundary follows the 
service area boundary for 9.65 miles to the eastern edge of the area, 
continuing to follow the 9,200 foot contour line. The boundary then 
intersects Bear Creek. Here the nonattainment boundary diverges from 
the service area boundary (9,200 foot contour line). The nonattainment 
boundary continues in a west, southwest direction for 0.92 miles from 
the intersection of the 9,200 foot contour line and Bear Creek to the 
top of ski lift number 9 in the Telluride Ski Area at an elevation of 
about 11,900 feet. The boundary then shifts and runs in a north-
westerly direction for 0.83 miles from the top of lift 9 to the top of 
lift 7, which is located at an elevation of 10,490 feet. From the top 
of lift 7, the nonattainment boundary continues in a north-westerly 
direction for 0.5 miles to the intersection of lift 3 with the 10,000 
foot control line. The nonattainment boundary follows the 10,000 foot 
contour line in a south, south-west direction for 3.2 miles, until it 
intersects Skunk Creek. Here the boundary diverges from the 10,000 foot 
contour line and follows Skunk Creek in a northerly direction for 2.25 
miles. At the intersection of Skunk Creek and Colorado State Highway 
145, the nonattainment boundary leaves the creek and follows Highway 
145 in a northerly direction until it meets the service area boundary 
as it existed prior to changes adopted in 1991.
    The boundary was determined to be the reasonable Telluride air shed 
by considering factors such as local topography, meteorology, emissions 
sources, land use practices, and tourism. EPA is proposing to replace 
the boundary description currently in 40 CFR 81.306 with this revised 
description to more clearly define the nonattainment area.

III. Implications Of This Action

    EPA is proposing partial approval of the elements (excluding the 
quantitative milestones element) of the PM10 SIP requirements for 
the Telluride, Colorado nonattainment area that were due on November 
15, 1991 and submitted to EPA on March 17, 1993. EPA is proposing 
conditional approval of the quantitative milestones element. EPA is 
proposing full approval of the PM10 contingency measures for the 
Telluride nonattainment area, as submitted to EPA on December 9, 1993. 
As noted, additional submittals for the initial moderate PM10 
nonattainment areas (i.e., nonattainment new source review program 
requirements) are due independent of the SIP requirements addressed in 
this action. EPA will determine the adequacy of any such submittal as 
appropriate.
    EPA is also proposing to amend the boundary description for the 
Telluride nonattainment area to clarify the original description.

IV. Request for Public Comments

    The EPA is requesting comments on all aspects of this proposal. As 
indicated at the outset of this document, EPA will consider any 
comments received by July 25, 1994.

V. Executive Order (EO) 12866

    This action has been classified as a Table 2 action by the Regional 
Administrator under the procedures published in the Federal Register on 
January 19, 1989 (54 FR 2214-2225), as revised by an October 4, 1993, 
memorandum from Michael H. Shapiro, Acting Assistant Administrator for 
Air and Radiation. A future document will inform the general public of 
these tables. On January 6, 1989, the Office of Management and Budget 
(OMB) waived Table 2 and Table 3 SIP revisions (54 FR 2222) from the 
requirements of section 3 of E.O. 12291 for two years. The EPA has 
submitted a request for a permanent waiver for Table 2 and Table 3 SIP 
revisions. The OMB has agreed to continue the waiver until such time as 
it rules on EPA's request. This request continues in effect under E.O. 
12866 which superseded E.O. 12291 on September 30, 1993. OMB has 
exempted this regulatory action from E.O. 12866 review.

VI. Regulatory Flexibility

    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. 604. 
Alternatively, EPA may certify that the rule will not have a 
significant economic 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 50,000.
    Approvals and conditional approvals of SIP submittals under section 
110 and subchapter I, part D of the Clean Air Act do not create any new 
requirements, but simply approve requirements that the State is already 
imposing. Therefore, because the Federal SIP-approval does not impose 
any new requirements, I certify that it does not have a significant 
impact on small entities affected. Moreover, due to the nature of the 
federal-state relationship under the Clean Air Act, preparation of a 
regulatory flexibility analysis would constitute federal inquiry into 
the economic reasonableness of state action. The Clean Air Act forbids 
EPA to base its actions concerning SIPs on such grounds. Union Electric 
Co. v. U.S. E.P.A., 427 U.S. 246, 256-66 (1976); 42 U.S.C. 7410(a)(2).

List of Subjects

40 CFR Part 52

    Environmental protection, Air pollution control, Hydrocarbons, 
Intergovernmental relations, Nitrogen dioxide, Particulate matter, 
Reporting and record keeping requirements, Sulfur dioxide, Volatile 
organic compounds.

40 CFR Part 81

    Air pollution control, National parks, Wilderness areas.

    Authority: 42 U.S.C. 7401-7671q.

    Dated: June 15, 1994.
Jack W. McGraw,
Acting Regional Administrator.
[FR Doc. 94-15305 Filed 6-22-94; 8:45 am]
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