Clean Air Act Approval and Promulgation of PMINF10 Implementation Plan for Colorado

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.

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Source category Control measure PM10 emissions reduction Effective date

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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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