Clean Air Act Approval and Promulgation of State Implementation Plan for Colorado; Carbon Monoxide Attainment Demonstrations and Related SIP Elements for Denver and Longmont; Clean Air Act Reclassification

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 52 and 81

[CO43-2-6865; CO43-1-6931; FRL-5532-07]

Clean Air Act Approval and Promulgation of State Implementation

Plan for Colorado; Carbon Monoxide Attainment Demonstrations and

Related SIP Elements for Denver and Longmont; Clean Air Act

Reclassification

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice of Proposed Rulemaking.

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SUMMARY: The Environmental Protection Agency today proposes approval of

the State Implementation Plan (SIP) revisions submitted by the State of

Colorado for the purpose of bringing about the attainment of the

national ambient air quality standards (NAAQS) for carbon monoxide

(CO). The implementation plan revisions were submitted by the State to

satisfy certain Federal requirements for an approvable nonattainment

area CO SIP for Denver and Longmont. This action includes proposed

approval of revisions to Colorado Regulations 11 (vehicle inspection

and maintenance) and 13 (oxygenated fuels) submitted to satisfy

conditions in the SIP. It also includes proposed reclassification of

the Denver CO nonattainment area from Moderate to Serious. The

rationale for the approvals and reclassification are set forth in this

document. Additional information is available at the address indicated

below.

DATES: Comments on this proposed action must be received in writing by

August 8, 1996.

ADDRESSES: Comments should be addressed to: Richard R. Long, Director

of Air Programs (8P2-A), Environmental Protection Agency, Region VIII,

999 18th Street, Suite 500, Denver, Colorado 80202-2466.

Copies of the State's submittals and other information are

available for inspection during normal business hours at the following

locations: Environmental Protection Agency, Region VIII, Air Programs,

999 18th Street, 3rd Floor, South Terrace, Denver, Colorado 80202-2466;

and Colorado Air Pollution Control Division, 4300 Cherry Creek Dr.

South, Denver, Colorado 80222-1530.

FOR FURTHER INFORMATION CONTACT: Jeff Houk at (303) 312-6446.

SUPPLEMENTARY INFORMATION:

I. Background

The air quality planning requirements for moderate CO nonattainment

areas are set out in sections 186-187 of the Clean Air Act (Act)

Amendments of 1990 (CAAA) which pertain to the classification of CO

nonattainment areas and to the submission requirements of the SIP's for

these areas, respectively. The EPA has issued a ``General Preamble''

describing EPA's preliminary views on how EPA intends to review SIP's

and SIP revisions submitted under Title I of the Act, [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 today's

proposal and the supporting rationale. In today's rulemaking action on

the Denver and Longmont CO SIPs, EPA is proposing to apply its

interpretations taking into consideration the specific factual issues

presented. Thus, EPA will consider any timely submitted comments before

taking final action on today's proposal.

This Federal Register document specifically addresses several

requirements of the 1990 CAAA which were required to be submitted no

later than November 15, 1992, and which the State did not submit by

that date. These requirements include an attainment demonstration,

contingency measures and, for Denver, a vehicle miles travelled

forecasting and tracking program and transportation control measures.

EPA made a formal finding that the State had failed to submit these SIP

revisions in a letter to Governor Roy Romer dated January 15, 1993.

This Federal Register document also addresses revisions to Regulations

11 and 13, submitted by the State of Colorado to implement portions of

the control strategy relied upon by the attainment demonstration.

Section 187(a)(7) required those States containing CO nonattainment

areas with design values greater than 12.7 parts per million (ppm) to

submit, among other things, an attainment demonstration by November 15,

1992, demonstrating that the plan will provide for attainment by

December 31, 1995 for moderate CO nonattainment areas and December 31,

2000 for serious CO nonattainment areas. The attainment demonstration

must include a SIP control strategy, which is also due by November 15,

1992. The SIP control strategy for a given nonattainment area must be

designed to ensure that the area meets the specific annual emissions

reductions necessary for reaching attainment by the deadline. In

addition, section 187(a)(3) requires these areas to implement

contingency measures if any estimate of actual vehicle miles travelled

(VMT) or any updated VMT forecast for the area contained in an annual

report for any year prior to attainment exceeds the number predicted in

the most recent VMT forecast. Contingency measures are also triggered

by failure to attain the NAAQS for CO by the attainment deadline.

Contingency measures must be submitted with the CO SIP by November 15,

1992. Finally, a vehicle miles travelled forecasting and tracking

program is required by Section 187(a)(2)(A), and transportation control

measures are required for Denver by Section 187(a)(2)(B). These

requirements are discussed in more detail below and in the Technical

Support Document for this proposed action.

Longmont had been designated as unclassifiable/attainment prior to

passage of the 1990 CAAA. However, a special monitoring study in 1988-

89 recorded an exceedance of the NAAQS in Longmont. As a result, EPA

Region VIII recommended that the Governor designate this area

nonattainment, and on March 15, 1991, the Governor submitted a

nonattainment designation for this area that was later codified by EPA

at 40 CFR Part 81. Since this area had never had a SIP, EPA interpreted

Section 172 of the Act to require an attainment demonstration for

Longmont. Contingency measures under Section 172(c)(9) were also

required. On January 15, 1993, EPA made a formal finding that the State

had failed to submit these SIP revisions for Longmont.

On July 11, 1994 and July 13, 1994, Governor Roy Romer submitted

comprehensive revisions to the Colorado SIP. The carbon monoxide SIP

element submittals for Denver and Longmont addressed the outstanding

CAA requirements discussed above, as well as other CAA mandates. The

July 11, 1994 CO SIP revision for Denver was developed primarily by the

Colorado Department of Health's Air Pollution Control Division (APCD),

the Colorado Air Quality Control Commission (AQCC), and the Regional

Air Quality Council (RAQC), which represents local government and

citizen interests. The July 13, 1994 CO SIP revision for Longmont was

developed primarily by the APCD, in consultation with the City of

Longmont.

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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.1 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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\1\ 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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The 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]. The EPA's completeness criteria for SIP submittals

are set out at 40 CFR Part 51, Appendix V (1991), as amended by 57 FR

42216 (August 26, 1991). 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 within six months after receipt of the

submission.

The AQCC held a public hearing on June 16, 1994 to entertain public

comment on the implementation plan revisions for Denver and Longmont.

Following the public hearing, the SIP revisions were adopted by the

AQCC, and forwarded to the Colorado Legislative Council for review.

(Under Colorado law, SIP revisions imposing new or revised controls on

mobile sources must be reviewed and accepted by the Colorado

Legislative Council.) The AQCC held an emergency hearing on July 7,

1994, to address concerns with the Denver SIP raised by the Legislative

Council, and on July 11 and July 13, 1994, the SIP revisions were

submitted to EPA by the Governor for approval.

The SIP revision was reviewed by EPA to determine completeness

shortly after its submittal, in accordance with the completeness

criteria set out at 40 CFR Part 51, Appendix V (1991), as amended by 57

FR 42216 (August 26, 1991). The submittal was found to be complete, and

a letter dated July 14, 1994 was forwarded to the Governor indicating

the completeness of the submittal and the next steps to be taken in the

review process. The applicable Clean Air Act requirements and EPA's

rationale for its proposed actions are discussed below.

Denver

A. Attainment Demonstration and Control Strategies

(1) Attainment Demonstration

As noted, CO nonattainment areas with design values greater than

12.7 ppm were required to submit a demonstration by November 15, 1992,

that the plan will provide for attainment by December 31, 1995 for

moderate CO nonattainment areas and December 31, 2000 for serious CO

nonattainment areas. APCD conducted an attainment demonstration using

urban areawide modeling in conjunction with intersection modeling for a

modeling region encompassing the Denver nonattainment area.

The CO NAAQS are for 1-hour and 8-hour periods and are not to be

exceeded more than once per year. The 1-hour CO NAAQS is 35 ppm (40 mg/

m3) and the 8-hour CO NAAQS is 9 ppm (10 mg/m3). The

demonstration predicted that the highest 8-hour design concentration as

of the attainment date will be 8.91 ppm, thus demonstrating attainment

of the 8-hour CO NAAQS. No demonstration was required to be carried out

for the 1-hour NAAQS, as Denver has not violated this NAAQS since

before the 1990 CAAA were enacted. The same strategies which bring the

area into attainment with the 8-hour NAAQS will also contribute to

reduced 1-hour concentrations. The modeled attainment demonstration is

discussed in greater detail below.

(a) Policy Issues: Reclassification to Serious and Applicability of

Serious Area SIP Requirements

(i) Reclassification to Serious. During the SIP development

process, the RAQC conducted an exhaustive review of control strategies

for use in demonstrating attainment of the CO NAAQS by the Clean Air

Act-mandated deadline for moderate areas of December 31, 1995. Even

with the oxygenated fuels program and an enhanced I/M program in place,

the RAQC and APCD determined that a 30% reduction in emissions would

still be needed to attain the NAAQS by this date. Any measures would

need to be implemented in the 18-month period between SIP adoption (in

June 1994) and the attainment date, ruling out many potential

strategies with longer implementation horizons. The RAQC considered

several aggressive strategies, including a mandatory no-drive day for

high emitting vehicles, but was unable to identify a package of

strategies that would provide the necessary emission reductions by

December 31, 1995.

As a result, the RAQC recommended to the AQCC that the Denver area

seek reclassification to serious. If Denver were reclassified to

serious, the applicable attainment date would become December 31, 2000

(CAA Section 186(a)(1)). The AQCC adopted this recommendation, and the

Governor formally requested reclassification to serious in his July 11,

1994 letter submitting the SIP. As part of this Federal Register

document, EPA is proposing to reclassify the Denver-Boulder

nonattainment area to serious.

EPA had originally intended to rely upon the authority for

reclassification provided by Section 110(k)(6) of the Clean Air Act.

This paragraph provides broad authority for EPA to correct previous

approvals, disapprovals, designations, and classifications based on new

information. However, air quality data collected during calendar year

1995 show that the Denver area experienced two exceedances of the CO

NAAQS in 1995 at the CAMP monitor. Because of this, Denver cannot

demonstrate attainment of the NAAQS by the statutory December 31, 1995

attainment date for moderate areas, and must be reclassified, by

operation of law, to serious. Under Section 186(b)(2)(A), a moderate

carbon monoxide nonattainment area must be reclassified as serious by

operation of law if the Administrator finds that the area has failed to

attain the CO NAAQS. Pursuant to Section 186(b)(2)(B), EPA must publish

a document in the Federal Register identifying those areas that failed

to attain the NAAQS and the resulting classifications. In this

document, EPA is proposing to find that the Denver/Boulder carbon

monoxide nonattainment area did not attain the NAAQS by the required

attainment date of December 31, 1995, and to revise the area's

classification for carbon monoxide in 40 CFR Part 81 from moderate to

serious.

(ii) Impacts of Reclassification to Serious. Areas classified as

serious are required to attain the CO NAAQS no later than December 31,

2000. In addition, the following additional requirements of CAA Section

187 apply:

Gasoline sold during the winter months must contain a level of

oxygen necessary to attain the NAAQS. (CAA Section 187(b)(3))

A mandatory employer-based trip reduction program must be adopted

and implemented, unless it can be shown that such a program is not

necessary to demonstrate attainment of the NAAQS. (CAA Section

187(b)(2), referencing CAA Section 182(d)(1)(B))

A December 31, 1995 milestone must be identified, and an economic

[[Page 36006]]

incentive program must be adopted and implemented if the milestone is

not achieved or if the area fails to attain the CO NAAQS by December

31, 2000. (CAA Section 187(d))

Vehicle miles travelled forecasts must be submitted for the period

1996-2000 (submittal of vehicle miles traveled forecasts for 1993-1995

is required for moderate areas). (CAA Section 187(a)(2)(A))

Additional requirements for the content and analysis of

transportation plans, programs and projects apply under the EPA/DOT

transportation conformity regulations (58 FR 62215, November 24, 1993).

The oxygenated gasoline, VMT forecast, and conformity requirements

are discussed elsewhere in this document.

(iii) December 31, 1995 milestone demonstration. CAA Section 187(d)

requires areas classified as serious to submit a demonstration no later

than March 31, 1996, that the area has achieved CO emission reductions

equivalent to the total of the specified annual emission reductions

required by December 31, 1995. The Act does not provide further

guidance on the form or content of the milestone itself, the specified

annual emission reductions, or the nature of the milestone

demonstration. EPA has not issued guidance on this matter.

Since the Act does not prescribe a methodology for determining a

milestone and EPA has not issued guidance for this purpose, the State

has chosen to use its 1995 base case emission inventory as the

milestone (Section XII-D of the SIP). The milestone level is 1396 tons

per day in the nonattainment area; this level represents progress

toward attainment from the 1988 level of 1709 tons per day.

(iv) Employer-based trip reduction program (the ECO program). CAA

Section 187(b)(2) requires areas classified as serious to adopt the

measures required by Section 182(d)(1). These measures consist of

transportation control measures (CAA Section 182(d)(1)(A)) and a

mandatory employer-based travel reduction program (commonly known as

the Employee Commute Options, or ECO, program) (CAA Section

182(d)(1)(B)). Section 187(b)(2) also provides that, in any area

defined as a ``covered area'' under the Clean Fuel Fleet Program

requirements of Section 246(a)(2)(B) (the Denver area meets this

definition), a SIP may exclude any of the Section 182(d)(1) measures if

(1) the SIP includes an explanation of why any measure was not adopted

and what emission reduction measure was adopted to provide comparable

reduction in emissions, or (2) the SIP contains reasons why such

reduction is not necessary to attain the national primary ambient air

quality standard for CO. (As a moderate area, Denver was already

required by the ``Special Rule for Denver,'' Section 187(a)(2)(B), to

address the transportation control measure requirements of Section

182(d)(1)(A). These requirements are discussed in Chapter X of the

SIP.)

The SIP demonstrates that no TCMs are necessary to provide for

attainment of the NAAQS by December 31, 2000 (attainment demonstration,

Tables XII-1 and XII-2). However, several TCMs were adopted as part of

the SIP, including transportation management associations to encourage

and provide technical support for voluntary employer-based trip

reduction activities; financial incentives for subsidized employee

transit passes and other travel reduction strategies for downtown

Denver employees; transit passes for students at the Auraria campus in

downtown Denver; high-occupancy vehicle lanes on Broadway and Lincoln,

two major arterials providing access to the central business district;

and improved traffic signalization in the central business district and

elsewhere in the nonattainment area. Appendix X-A of the SIP also

discusses several other TCMs that were adopted and implemented as part

of the 1979 and 1982 SIPs for Denver and remain in effect.

Section X.F. of the SIP provides the formal justification for

exclusion of the ECO program from the Denver SIP. However, on December

23, 1995, the President signed revisions to the ECO requirements of the

Clean Air Act. These revisions amended the Act to make submittal of a

SIP revision providing for the ECO program voluntary for areas which

are bumped up to a higher classification (and thus, newly made subject

to the requirement). Thus, the State would have no longer been required

to submit such program, even if EPA had initially interpreted the Act

to require this program for Denver.

(b) Technical Evaluation of Attainment Demonstration

EPA is proposing to approve the State's attainment demonstration

for Denver. EPA has determined that the State correctly applied

national guidance in conducting modeling of the entire region and of

six intersections that could potentially cause violations of the CO

NAAQS. In addition, the State complied with a Region VIII request to

conduct modeling of downtown intersections above and beyond the six

required by national guidance. However, due to the factors described

below, the model could not be properly applied to two high-traffic

downtown intersections: Speer/Auraria and Broadway/Colfax. Model

predictions at these two sites were affected by uncertainties in

meteorological and motor vehicle emissions inputs. In addition, the

modeled predictions of high ambient values at these intersections were

not supported by saturation monitoring data obtained at the same

locations. Thus, the attainment demonstration is based on modeled and

monitored values at a third downtown intersection, CAMP, which has

historically recorded the highest CO concentrations in the Denver metro

area. These issues are discussed in greater detail below.

A variety of specialized models were used to model the Denver area

carbon monoxide concentrations in accordance with EPA guidance. The

Urban Airshed Model (UAM) was used to simulate regional concentrations

during two historical episodes when very high carbon monoxide levels

occurred. During these same episodes the CAL3QHC model was used to

simulate concentrations from local streets and roadways. The outputs

from both models were added together so that total predicted

concentrations could be compared with values actually measured at the

monitoring sites during these episodes. These comparisons determine if

the modeling meets the performance criteria prescribed in the UAM

guidance document, and in the modeling protocol. For both episodes

there was a tendency for the UAM/CAL3QHC model to underpredict

concentrations. However, the degree of underprediction was within the

limits specified in EPA UAM Guidance documents, and in the modeling

protocol.

The validated UAM/CAL3QHC model was then applied in the attainment

year (2000) to determine whether proposed control strategies are

sufficient to meet the 8-hour ambient air quality standard (9.0 ppm).

The same meteorological conditions used in the model validation runs

were used in the 2000 model runs. However, the 2000 runs were modeled

with revised emission input files to examine the benefits of the

various control strategies. The 2000 attainment runs showed that the

control strategies in the SIP are sufficient to reduce carbon monoxide

concentrations to less than 9.0 ppm at all locations in the

nonattainment area.

The Denver CO modeling protocol was approved by EPA Region VIII in

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May 1992. Specific intersections to be modeled were not identified in

the protocol. The State showed attainment on each of the six highest

ranked intersections selected for modeling, following screening

criteria contained in ``Guideline for Modeling CO from Roadway

Intersections'', EPA-454/R-92-005. The State subsequently found that

the six busiest intersections for traffic congestion were located in

the suburban areas, where background air quality levels are relatively

low. Application of CAL3QHC at these six locations, combined with UAM

predicted background levels, showed the year 2000 concentrations at

levels well within the CO NAAQS. The Region requested the State to

model an additional intersection in the central business district, to

ensure that control strategies provide for attainment at hot spot

locations in the urban core area, not just at suburban locations

exposed to significantly lower background concentrations.

The State performed preliminary CAL3QHC modeling at three

additional intersections in the Downtown area: Speer & Auraria;

Broadway & Colfax; and Broadway & Champa. These preliminary 1995

results showed predicted concentrations at Speer/Auraria and Broadway/

Colfax up to 6 ppm higher than concentrations modeled at the CAMP

monitor (Broadway & Champa). Because of uncertainties related to the

validity of meteorological inputs used in the model, the State opted

not to include the CAL3QHC modeling results for the two higher

intersections in the current SIP, deferring consideration of these

locations until additional saturation monitoring studies could be

conducted at these intersections. The State selected Broadway and

Champa as the intersection to use in the SIP attainment demonstration

because the on-site air quality and meteorology monitoring data

available at this location provided more confidence in the results,

i.e., produced modelled concentrations that were in good agreement with

concentrations actually monitored at the site. There are significant

and unique micro-meteorological effects influencing each of the three

central business district intersections, including: high-rise office

buildings, channeling of the wind down ``urban street canyons'', and

urban heat island effects. Since the Diagnostic Wind Model (DWM) used

with UAM does not include any of these effects, the State did not

consider the meteorological outputs from DWM appropriate for use in

microscale modeling.

The State's intersection analysis is consistent with national

policy and other recent UAM/CAL3QHC modeling applications. Additional

information on the attainment demonstration modeling is included in the

Technical Support Document for this action.

(2) Control Strategies

Section 172(c)(1) requires the plans for all nonattainment areas to

provide for the implementation of RACM (including RACT) as

expeditiously as practicable and to provide for attainment of the

NAAQS. The EPA interprets this requirement to impose a duty on all

nonattainment areas to consider the available control measures, and to

adopt and implement such measures as are reasonably available for

implementation in the area and necessary for attainment of the NAAQS as

components of the area's attainment demonstration. The EPA has reviewed

the State's explanation and associated documentation and concluded that

it adequately justifies the control measures to be implemented. EPA is

proposing to approve several of the control strategies. The exact

nature of EPA's proposed approvals is discussed in more detail below

and in the Technical Support Document for today's action.

The Denver CO SIP takes credit for several control programs in the

attainment demonstration. Those identified in Chapter V of the SIP as

``baseline strategies'' are measures which were in existence at the

time of CO SIP development, and for which no further State regulatory

action was required. EPA is not taking action on these control

strategies through this SIP revision, as these are strategies which

have been adopted through previous SIP revisions and have been or are

being acted on in other Federal Register documents. Those identified as

``additional control strategies'' are measures which were newly-

considered and adopted for the attainment demonstration, and which are

being acted on in this SIP revision.

The baseline strategies include the Federal motor vehicle control

program, the 2.7% oxygenated fuels program (approved in the Federal

Register on July 25, 1994 (59 FR 37698)), the Enhanced inspection and

maintenance (I/M) program (conditionally approved in the Federal

Register on November 8, 1994 (59 FR 55584)), various transportation

system improvements, and the woodburning control measures adopted as

part of the Denver PM10 SIP (approved in the Federal Register on July

25, 1994 (59 FR 37698)).

In addition, Section 246 of the Clean Air Act requires that the

State adopt and implement the Clean Fuels Fleet Program, an alternative

fuels program for certain commercial and governmental fleet operations.

AQCC Regulation 17, the Clean Fuels Fleet Program regulation, was

adopted by the AQCC on May 5, 1994, and submitted with the Denver CO

SIP. (The full Clean Fuels Fleet Program SIP was submitted to EPA on

October 17, 1994.) A wide variety of non-mandated alternative fuels

programs are also underway in the Denver area. No credit is taken for

Regulation 17 or any of the other programs in the attainment

demonstration, and EPA will act on the Clean Fuels Fleet Program in the

Federal Register at a later date.

Several additional control strategies have been formally

incorporated into or committed to in the Denver CO SIP to provide for

attainment of the CO NAAQS by December 31, 2000. These measures are

described in Chapter VI of the SIP and are discussed below.

(a) 3.1% oxygenated fuels program. In the CO SIP, the State made a

commitment, which has since been met, to implement and adopt a 3.1%

oxygenated fuels program, providing additional benefit over the 2.7%

program already required of the area by Section 211(m) of the Act. The

program is being implemented in two phases. In the winter of 1994-95, a

``maximum blending'' program took effect, which requires gasoline

suppliers using methyl tert-butyl ether as an oxygenate to blend at the

2.7% oxygen level (the maximum allowed by Federal regulations), and

suppliers using ethanol as an oxygenate to blend at the 3.5% oxygen

level (also the maximum allowed by Federal regulations). The market

share of ethanol in the Denver area has exceeded 50% in recent years,

and this approach is expected to result in at least a 3.1% oxygen

content during each winter season. If the maximum blending approach

should fail to provide for at least a 3.1% oxygen content, the SIP

provides that in subsequent winter seasons an averaging program,

pursuant to EPA guidance for such programs, will take effect.

AQCC Regulation 13 governs the oxygenated fuels program. The SIP

committed to revise this regulation in two steps. Reg 13 was revised to

incorporate the maximum blending approach for the winter of 1994-95 by

the AQCC on July 19, 1994. Reg 13 was revised to incorporate the more

complex 3.1% averaging program on October 20, 1994. Both sets of

regulation revisions were submitted by the Governor for EPA approval on

September 29, 1995. The

[[Page 36008]]

September 29, 1995 submittal was determined complete on November 30,

1995.

(b) Increased I/M failure rate for pre-1982 vehicles. The SIP

includes a commitment, which has since been met, to revise Regulation

11, which governs the I/M program, to incorporate more stringent

emissions cutpoints which will increase the failure rate for pre-1982

vehicles from the current 14-26% to approximately 40%. Pre-1982

vehicles have less advanced emission control system technology,

resulting in higher CO emission levels, and the more stringent

cutpoints for these vehicles will result in the identification and

repair of a greater number of high-emitting vehicles than are captured

by the present I/M program (an increase of approximately 70,000

vehicles per year). These regulation revisions were adopted by the AQCC

on September 22, 1994, and submitted by the Governor for EPA approval

on September 29, 1995. The September 29, 1995 submittal was determined

complete on November 30, 1995.

(c) Prohibition on the re-registration of abandoned and impounded

pre-1982 vehicles sold at auction. This element of the SIP requires

local governments in the Denver area to modify their ordinances or

procedures for disposing of pre-1982 abandoned and impounded vehicles

to prohibit purchasers from obtaining any form of title to the

vehicles. These vehicles may be sold for scrappage or dismantling only.

This measure will accelerate the normal rate of removal of vehicles of

this age from the fleet, by preventing up to 5,000 vehicles of this

type from being re-registered. Elimination of this many pre-1982

vehicles could reduce regional CO emissions by up to 5 tons per day.

However, because of the difficulty of defining a concise emission

reduction, the State does not take credit for this strategy in the

attainment demonstration.

B. Transportation Control Measures

Section 187(a)(2)(B) (Special Rule for Denver) requires the State

to submit a SIP revision that includes the TCMs as required in Section

182(d)(1)(A) of the Act, for the purpose of reducing CO emissions. The

SIP may exclude any of the Section 182(d)(1)(A) measures if 1) the SIP

includes an explanation of why any measure was not adopted and what

emission reduction measure was adopted to provide comparable reduction

in emissions, or 2) the SIP contains reasons why such reduction is not

necessary to attain the national primary ambient air quality standard

for CO.

The TCM SIP revision is contained in Chapter X of the Denver CO

SIP. The TCMs adopted as part of the SIP are listed below. See the

Technical Support Document for today's document and the SIP itself for

a more detailed description of these measures.

(1) Employer-based transportation emission management programs

promoted and encouraged by transportation management associations and

financial incentives.

(2) Auraria transit pass.

(3) Conversion of Broadway/Lincoln Bus Lanes to Bus/HOV.

(4) Improved Traffic Signalization.

(5) Other Measures.

Appendix X-A contains the State's assessment of the measures listed

in Section 108(f), including a comprehensive description of strategies

already in place in Denver and the newly-adopted measures. Several TCMs

have already been adopted as part of the SIP in previous ozone and CO

SIP revisions, and have been approved by EPA (45 FR 51199, August 1,

1980, and 48 FR 55284, December 12, 1983). Appendix X-A also describes

projects and programs which are not being included in the SIP but

nevertheless provide some emission reduction benefit.

EPA is proposing to approve this element of the Denver CO SIP. The

SIP satisfies the requirement of Section 187(a)(2)(B) to either include

the TCMs or provide a justification for not including them. The

attainment demonstration for the SIP does not include credit for any of

the TCMs; however, the above measures were adopted as enforceable

provisions of the SIP.

C. Vehicle Miles Traveled Forecasting and Tracking

Section 187(a)(2)(A) of the Clean Air Act Amendments of 1990

required EPA, in consultation with the U.S. Department of

Transportation (DOT), to develop guidance for states to use in

complying with the VMT forecasting and tracking provisions of Section

187. A Notice of Availability for the resulting Section 187 VMT

Forecasting and Tracking Guidance was published in the Federal Register

on March 19, 1992. Section 187(a)(2)(A) requires Denver to submit a SIP

revision providing for a VMT forecasting and tracking program, and

contingency measures for implementation in the event that a VMT

forecast is exceeded. The specific requirements are discussed in detail

in the Technical Support Document for today's action.

The State of Colorado has submitted a SIP revision to EPA in order

to satisfy the requirements of Section 187(a)(2)(A) and Section

187(a)(3). In order to gain approval, the State submittal must provide

for each of the following mandatory elements: (1) a forecast of VMT in

the non-attainment area for each year prior to the attainment year; (2)

a provision for annual updates of the forecasts along with a provision

for annual reports describing the extent to which the forecasts proved

to be accurate; these reports shall provide estimates of actual VMT in

each year for which a forecast was required; (3) adopted and

enforceable contingency measures to be implemented without further

action by the State or the Administrator if actual annual VMT or an

updated forecast exceeds the most recent prior forecast or if the area

fails to attain the CO NAAQS by the attainment date.

(1) VMT Forecasts

Section 187(a)(2)(A) requires that the State include in its SIP

submittal a forecast of VMT in the non-attainment area for each year

before the year in which the SIP projects the National Ambient Air

Quality Standard for CO will be attained. The forecasts are to be based

on guidance developed by EPA in consultation with DOT, i.e., the

Section 187 VMT Forecasting and Tracking Guidance. Table XIV-2 of the

SIP contains the required forecasts of annual VMT for the years 1993-

2001.

(2) Annual VMT Updates/Reports

Section 187(a)(2)(A) specifies that the SIP revision provide for

annual updates of the VMT forecasts and annual reports that describe

the accuracy of the forecasts and that provide estimates of actual VMT

in each year for which a forecast was required. The Section 187 VMT

Forecasting and Tracking Guidance specifies that annual reports should

be submitted to EPA by September 30 of the year following the year for

which the VMT estimate is made. The SIP commits to the submission of

these annual reports and identifies responsibilities among the various

transportation agencies in Denver to develop the reports.

(3) Contingency Measures

Section 187(a)(3) specifies that the State, in its SIP revision,

adopt specific, enforceable contingency measures to be implemented if

the annual estimate of actual VMT or a subsequent VMT forecast exceeds

the most recent prior forecast of VMT or if the area fails to attain

the CO NAAQS by the attainment date. Implementation of the identified

contingency measures must not require further rulemaking activities by

the

[[Page 36009]]

State or EPA. Certain actions, such as notification of sources, would

probably be needed before a measure could be implemented effectively.

The State has met this requirement, as discussed in Section D. below.

The State of Colorado has submitted a SIP revision implementing each of

the required elements required by Section 187(a)(2)(A) and Section

187(a)(3) of the CAAA.

D. Contingency Measures

The Clean Air Act requires each CO nonattainment area with a design

value above 12.7 ppm at the time of classification to adopt contingency

measures that will take effect without further action by the State or

EPA upon a determination by EPA that an area failed to make reasonable

further progress or to attain the standards, as described in

Sec. 172(c)(9), or that actual or forecasted VMT exceeded a previous

forecast. Section 187(a)(3) requires the State to submit a SIP revision

containing contingency measures no later than November 15, 1992. The

State submitted these measures as part of the Denver CO SIP on July 11,

1994.

States may implement contingency measures early to obtain

additional emission reductions, without being required to adopt

replacement contingency measures to put in place should one of the

triggering events for implementation of contingency measures occur.

This policy is described in a memorandum from Tom Helms, Chief of the

OAQPS Ozone Policy and Strategies Group entitled ``Early Implementation

of Contingency Measures for Ozone and Carbon Monoxide Nonattainment

Areas,'' August 13, 1993.

As noted above, the State did not take credit in the attainment

demonstration for the TCMs adopted to meet the requirements of Section

187(a)(2)(B). Because these measures are surplus to the reductions

needed for attainment, the State has adopted these as the required

contingency measures as well. The Denver region is proceeding with

early implementation of these measures to obtain the additional

emission reductions they provide.

If a triggering event for contingency measures occurs, EPA will

review the status of implementation of the TCMs adopted in Chapter X of

the SIP. Each of the TCMs must be fully implemented in order to satisy

the contingency measures requirements of Sections 172 and 187. In

addition, the EPA/DOT transportation conformity regulation (58 FR

62235, November 24, 1993) requires DRCOG and USDOT to demonstrate that

SIP TCMs are being implemented or are on schedule for implementation

before making a conformity determination for transportation plans or

TIPs. This provides an extra degree of assurance that the contingency

measures will be implemented if needed.

Section XIII.C. of the SIP defines the target emissions reduction

level for contingency measures. Based on average projected annual VMT

growth between 1995 and 2000 and the modeled fleet emission factors for

those years, the State determined that minimum emission reductions of

26 tons per day in 1995 and 16 tons per day in 2000 represented the

minimum emission reduction levels for contingency measures pursuant to

EPA guidance. The TCMs, when fully implemented, are projected to

produce an emission reduction of 34 tons per day in the year 2000. The

emission reductions would be higher in earlier years, since the

baseline fleet emission factors to which the contingency measure

effectiveness would be applied are higher. Thus, the submittal

satisfies EPA's minimum criteria for contingency measure effectiveness.

E. Mobile Source Emissions Budgets and Transportation Conformity

Section 176(c)(1) of the Act directs that no department, agency, or

instrumentality of the federal government may permit any activity that

does not conform to a SIP. Section 176(c)(2) further specifies that

federally funded transportation improvement programs (TIPs), regional

transportation plans, and projects must conform to the SIP in order to

be adopted by the metropolitan planning organization. EPA and DOT

promulgated implementing regulations for this CAA provision on November

24, 1993 (58 FR 62235).

One key provision of the conformity regulations requires a

demonstration that emissions from the transportation plan and TIP are

consistent with the emissions budget in the SIP (Sections 93.118 and

93.119 of the conformity rule). The emissions budget is defined as the

level of mobile source emissions relied upon in the attainment and/or

maintenance demonstration to achieve compliance with the NAAQS in the

nonattainment area. The rule's requirements and EPA's policy on

emissions budgets are found in the Preamble to the transportation

conformity rule (58 FR 62193-96) and in the sections of the rule

referenced above. The SIP defines emissions budgets for the 1995

milestone year and the 2000 attainment year.

The 1995 budget is consistent with the mobile source emissions

estimate for the milestone year and is 1125 tons per day in the

nonattainment area. This budget no longer applies for conformity, since

that date has passed. For the year 2000, the SIP includes modeling for

scenarios with and without TCMs. The RAQC recommended that the AQCC

adopt the emissions budget for the scenario without TCMs as the budget

to be used for conformity (825 tons per day in the nonattainment area).

However, the AQCC adopted (and the Governor submitted) an emission

budget of 808 tons per day in the nonattainment area. This lower budget

reflected some (not all) of the emissions reductions associated with

the implementation of the TCMs. The AQCC felt that this lower budget

would provide a margin of safety for attainment and would provide an

extra incentive (through the conformity requirements) for

implementation of the TCMs.

Subsequent to submittal of the SIP, DRCOG completed an initial

conformity analysis for the 2015 transportation plan and the 1995-2000

TIP, and found that the plan and TIP could not conform to the lower

budget adopted by the AQCC and submitted to EPA. In response, the RAQC

adopted a resolution requesting that the AQCC revise the SIP to raise

the emission budget to the attainment level of 825 tons per day. The

AQCC adopted this SIP revision after a public hearing on February 16,

1995, and the Governor submitted this SIP revision on July 18, 1995.

The Governor's July 18, 1995 letter withdraws the 808 ton per day

emission budget submitted on July 11, 1994. This leaves the default

budget of 825 tons per day from the attainment demonstration as the

applicable budget under EPA's conformity rule. Since EPA is proposing

to approve the attainment demonstration, the 825 ton per day budget

that the attainment demonstration is based on would be approved by

default, and no separate action is necessary on the July 18, 1995

submittal of this budget.

Section 93.106(b) of the conformity rule requires that the

transportation plans in moderate nonattainment areas reclassified to

serious meet certain content and analysis requirements. These new

requirements would affect plans adopted two years after

reclassification to serious. Once EPA reclassifies the Denver area to

serious, these requirements will take effect two years thereafter.

DRCOG's transportation planning methodologies already meet many of

these requirements.

[[Page 36010]]

Longmont

A. Background of Sip Revision

Pursuant to the requirements of the 1990 Clean Air Act Amendments,

each State was required to identify its nonattainment areas and submit

descriptions of these areas for EPA promulgation in 40 CFR Part 81.

Longmont had been designated as unclassifiable/attainment prior to

passage of the 1990 Amendments. However, a special monitoring study in

1988-89 recorded an exceedance of the NAAQS in Longmont. (This study is

described in Chapter II of the Longmont SIP.) As a result, EPA Region

VIII recommended that the Governor designate this area nonattainment in

a letter dated January 15, 1991. In a letter dated March 15, 1991,

Governor Roy Romer submitted a request that Longmont be designated a

moderate nonattainment area, and submitted boundaries for the new area.

The designation, classification and boundaries were promulgated by EPA

in the Federal Register on November 6, 1991 (56 FR 56733).

Since this area had never had a SIP, EPA interpreted Section 172 of

the Act to require an attainment demonstration for Longmont. As a

moderate area, the applicable attainment date for Longmont is December

31, 1995. Contingency measures under Section 172(b)(9) were also

required. On January 15, 1993, EPA made a formal finding that the State

had failed to submit these SIP revisions for Longmont.

On July 13, 1994, Governor Roy Romer submitted comprehensive

revisions to the Colorado SIP. The carbon monoxide SIP element

submittal for Longmont addressed the outstanding CAA requirements

discussed above, as well as other CAA mandates. EPA found this SIP

element complete on July 14, 1994. The CO SIP revision for Longmont was

developed primarily by APCD, in consultation with the City of Longmont.

The SIP development process is discussed in Chapter I of the SIP.

Throughout the remainder of this Federal Register document,

references are made to the ``Longmont area.'' This is a matter of

convenience; these references apply to the Longmont CO nonattainment

area as defined in 40 CFR Part 81 unless otherwise noted.

B. Attainment Demonstration and Control Strategies: Longmont

(1) Attainment Demonstration

A different approach was used for demonstrating attainment in

Longmont than the methodology used in Denver. Originally, the State

planned to develop the attainment demonstration for Longmont as part of

the modeling for Denver. However, it was discovered that the ambient

conditions which led to exceedances of the CO NAAQS in Denver were not

directly applicable to Longmont. After reviewing the results of the

1988-89 special monitoring studies, which suggested that exceedances

occur due to emissions on a neighborhood scale, and in consideration of

Longmont's small size and low traffic counts relative to conditions in

Denver, EPA concluded that the complex UAM/CAL3QHC modeling methodology

used in Denver was not necessary for demonstrating attainment in

Longmont. EPA recommended that a simple rollforward analysis, similar

to that used in attainment demonstrations for Colorado's smaller PM10

nonattainment areas, be used for Longmont. This decision is documented

in a July 26, 1993 letter from EPA to APCD.

The methodology used and the results are presented in Chapter IV of

the SIP. The SIP projects a second maximum concentration of 6.97 ppm at

the end of 1995, well below the 9.0 ppm NAAQS.

(2) Control Strategies

Section 172(c)(1) of the Act requires the plans for all

nonattainment areas to provide for the implementation of RACM

(including RACT) as expeditiously as practicable and to provide for

attainment of the NAAQS. EPA interprets this requirement to impose a

duty on all nonattainment areas to consider the available control

measures, and to adopt and implement such measures as are reasonably

available and necessary for attainment of the NAAQS as components of

the area's attainment demonstration. EPA has reviewed the State's

explanation and associated documentation and concluded that it

adequately justifies the control measures being implemented.

The Longmont CO SIP takes credit for several control programs in

the attainment demonstration. These control strategies, identified in

Table III.3 and discussed in Chapter V of the SIP, are measures which

were in existence at the time of CO SIP development, and for which no

further State regulatory action was required. EPA is not taking action

on these control strategies in this Federal Register document, as these

are strategies which have been adopted through previous SIP revisions

and have been or are being acted on in other Federal Register

documents. The attainment demonstration does not take credit for any

newly-adopted control strategies, nor are any such strategies included

in the SIP. In addition, Chapter V discusses several other activities

underway in the Longmont area that have emission reduction benefits.

However, these activities are not identified as control strategies and

are not reflected in the 1995 attainment emission inventory, and thus,

EPA is not incorporating these measures into the SIP.

The control strategies relied upon for the Longmont attainment

demonstration include the Federal motor vehicle control program, the

2.7% oxygenated fuels program (approved in the Federal Register on July

25, 1994 (59 FR 37698)), the enhanced inspection and maintenance (I/M)

program (conditionally approved in the Federal Register on November 8,

1994 (59 FR 55594)), various ongoing travel reduction strategies and

transportation system improvements, and woodburning control measures

from the Denver PM10 SIP (the woodburning program was approved in the

Federal Register on July 25, 1995 (59 FR 37698)).

The package of strategies incorporated in the attainment

demonstration is expected to reduce emisssions from 55.070 tons per day

in 1988 to 37.292 tons per day in 1995, for an overall reduction of

approximately 32%. The strategies result in a 1995 projected second

maximum concentration of 6.97 ppm.

C. Contingency Measures: Longmont

EPA's requirements for contingency measures are described above.

Unlike Denver, Longmont is not subject to the CAA Section 187(a)(2)(A)

requirement for a VMT forecasting and tracking program, and thus is not

required to implement contingency measures in the event that a VMT

forecast is exceeded. Contingency measures for Longmont were submitted

as part of the July 13, 1994 SIP.

The 3.1% oxygenated fuels program, adopted as part of the Denver CO

SIP, has been adopted as the contingency measure for Longmont. This

measure is being implemented in the entire six-county Denver

metropolitan area as required by the Clean Air Act, and thus is being

implemented in Longmont, even though it is not credited in the

attainment demonstration. EPA considers this to be early implementation

of the contingency measure, as provided for in the August 13, 1993 Tom

Helms memorandum referenced above.

Section V.C. of the SIP defines the target emissions reduction

level for contingency measures. VMT growth in Longmont was estimated at

3.1% per

[[Page 36011]]

year, which equates to CO emissions growth of 0.92 tons per year. The

3.1% oxygenated fuels program gives Longmont an additional incremental

emission reduction over the 2.7% program of 1.01 tons per year, which

exceeds the minimum emission reduction level. Thus, EPA's minimum

requirements for contingency measures are satisfied by the State's

submittal.

II. Implications of This Action

In today's action, EPA is proposing to approve SIP revisions

submitted by the Governor on July 11, 1994, July 13, 1994, and

September 29, 1995. Specifically, EPA is proposing to (1) approve the

July 11, 1994 attainment demonstration, VMT tracking and forecasting

program, TCM, and contingency measures submittals for Denver; (2)

approve the July 13, 1994 attainment demonstration and contingency

measures submittals for Longmont; and (3) approve the control

strategies for Denver, including the September 29, 1995 submittal of

revisions to Regulations 11 and 13 (I/M and oxygenated fuels).

In this document, EPA is also proposing to find that the Denver/

Boulder carbon monoxide nonattainment area did not attain the NAAQS by

the required attainment date of December 31, 1995, and to revise the

area's classification for carbon monoxide in 40 CFR Part 81 from

moderate to serious. This proposed finding is based on air quality data

revealing more than one exceedance of the CO NAAQS during calendar year

1995, resulting in a design value higher than the NAAQS for the period

1994-95. By action dated December 20, 1994, the EPA Administrator

delegated to the Regional Administrators the authority to determine

whether CO nonattainment areas attained the NAAQS, and to reclassify

those that did not.

III. Request for Public Comments

EPA is requesting comments on all aspects of today's proposal. As

indicated at the outset of this document, EPA will consider any

comments received by August 8, 1996.

IV. Executive Order (EO) 12866

Under EO 12866, 58 FR 51735 (October 4, 1993), EPA is required to

determine whether regulatory actions are significant and therefore

should be subject to OMB review, economic analysis, and the

requirements of the EO. The EO defines a ``significant regulatory

action'' as one that is likely to result in a rule that may meet at

least one of the four criteria identified in section 3(f) of the EO,

including, under paragraph (1), that the rule may ``have an annual

effect on the economy of $100 million or more or adversely affect, in a

material way, the economy, a sector of the economy, productivity,

competition, jobs, the environment, public health or safety, or State,

local, or tribal governments or communities.''

The SIP-related actions proposed today have been classified as

Table 3 actions for signature by the Regional Administrator under the

procedures published in the Federal Register on January 19, 1989 (54 FR

2214-2225), as revised by a July 10, 1995 memorandum from Mary Nichols,

Assistant Administrator for Air and Radiation. The Office of Management

and Budget has exempted these regulatory actions from EO 12866 review.

Likewise, EPA has determined that the finding of failure to attain

proposed today would result in none of the effects identified in

section 3(f) of the EO. Under Section 186(b)(2) of the Clean Air Act,

findings of failure to attain and reclassification of nonattainment

areas are based upon air quality considerations and must occur by

operation of law in light of certain air quality conditions. They do

not, in and of themselves, impose any new requirements on any sectors

of the economy. In addition, because the statutory requirements are

clearly defined with respect to the differently classified areas, and

because those requirements are automatically triggered by

classifications that, in turn, are triggered by air quality values,

findings of failure to attain and reclassification cannot be said to

impose a materially adverse impact on State, local, or tribal

governments or communities.

V. Regulatory Flexibility

Under the Regulatory Flexibility Act, 5 U.S.C. section 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.

sections 603 and 604). Alternatively, EPA may certify that the rule

will not have a significant impact on a substantial number of small

entities. Small entities include small businesses, small not-for-profit

enterprises, and government entities with jurisidiction over

populations that are less than 50,000.

SIP revision approvals under Section 110 and Subchapter I, Part D,

of the CAA do not create any new requirements, but simply approve

requirements that the State is already imposing. Therefore, because the

Federal SIP approval process does not impose any new requirements, EPA

certifies that this proposed rule would not have a significant impact

on any small entities affected. Moreover, due to the nature of the

Federal-State relationship under the CAA, preparation of a regulatory

flexibility analysis would constitute Federal inquiry into the economic

reasonableness of State actions. The CAA forbids EPA to base its

actions concerning SIPs on such grounds. Union Electric Co. v.

U.S.E.P.A., 427 U.S. 246, 256-266 (S. Ct. 1976); 42 U.S.C. section

7410(a)(2).

As discussed in section IV. of this document, findings of failure

to attain and reclassification of nonattainment areas under Section

186(b)(2) of the CAA do not, in and of themselves, create any new

requirements. Therefore, I certify that today's proposal does not have

a significant impact on small entities.

VI. Unfunded Mandates

Under Section 202 of the Unfunded Mandates Reform Act of 1995

(``Unfunded Mandates Act''), signed into law on March 22, 1995, EPA

must prepare a budgetary impact statement to accompany any proposed or

final rule that includes a Federal mandate that may result in estimated

costs to State, local, or tribal governments in the aggregate, or to

the private sector, of $100 million or more. Under Section 205, EPA

must select the most cost-effective and least burdensome alternative

that achieves the objectives of the rule and is consistent with

statutory requirements. Section 203 requires EPA to establish a plan

for informing and advising any small governments that may be

significantly or uniquely impacted by the rule.

EPA has determined that the SIP approval actions proposed today do

not include a Federal mandate that may result in estimated costs of

$100 million or more to either State, local or tribal governments in

the aggregate, or to the private sector. These Federal actions approve

pre-existing requirements under State or local law, and impose no new

Federal requirements. Accordingly, no additional costs to State, local

or tribal governments, or to the private sector, result from these

actions.

Likewise, EPA believes, as discussed in section IV of this

document, that the proposed finding of failure to attain and

reclassification to serious are factual determinations based upon air

quality data and must occur by operation of law and, hence, do not

impose any federal intergovernmental mandate, as defined in section 101

of the Unfunded Mandates Act.

[[Page 36012]]

List of Subjects

40 CFR Part 52

Environmental protection, Air pollution control, Carbon monoxide,

Intergovernmental relations, Reporting recordkeeping requirements.

40 CFR Part 81

Air pollution control.

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

Dated: June 24, 1996.

Jack W. McGraw,

Acting Regional Administrator.

[FR Doc. 96-17319 Filed 7-8-96; 8:45 am]

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