AIR QUALITY STANDARDS, DESIGNATIONS AND EMISSION BUDGETS

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DEPARTMENT OF PUBLIC HEALTH AND ENVIRONMENT

Air Quality Control Commission

AIR QUALITY STANDARDS, DESIGNATIONS AND EMISSION BUDGETS

5 CCR 1001-14

[Editor’s Notes follow the text of the rules at the end of this CCR Document.]

______________________________________________________________________

Pursuant to Colorado Revised Statutes § 24-4-103 (12.5), materials incorporated by

reference are available for public inspection during normal business hours, or copies

may be obtained at a reasonable cost from the Air Quality Control Commission (the

Commission), 4300 Cherry Creek Drive South, Denver, Colorado 80246-1530. The

material incorporated by reference is also available through the United States

Government Printing Office, online at www.govinfo.gov. Materials incorporated by

reference are those editions in existence as of the date indicated and do not include any

later amendments.

Unless otherwise indicated, any incorporation by reference of 40 CFR Section 93.118

are to the edition published March 14, 2012.

Ambient Air Quality Standards

I.A.

National Ambient Air Quality Standards

For National Ambient Air Quality Standards and associated ambient air

monitoring reference methods, see Title 40, CFR Part 50.

I.B.

Colorado Ambient Air Quality Standards (State Only)

I.B.1. Sulfur Dioxide (SO2)1

The actual concentration of sulfur dioxide at any given receptor site (no

greater than five meters above ground level) in the State of Colorado shall

not exceed a three-hour maximum of 700 micrograms per cubic meter

(ug/m3) (or 0.267 parts per million by volume (ppmv) at one atmosphere

and F25 degrees Celsius more than once in any twelve-month period.

Code of Colorado Regulations

Secretary of State

State of Colorado

CODE OF COLORADO REGULATIONS

5 CCR 1001-14

Air Quality Control Commission

ters above ground level) in the State of Colorado shall

not exceed a three-hour maximum of 700 micrograms per cubic meter

(ug/m3) (or 0.267 parts per million by volume (ppmv) at one atmosphere

and F25 degrees Celsius more than once in any twelve-month period.

Code of Colorado Regulations

Secretary of State

State of Colorado

CODE OF COLORADO REGULATIONS

5 CCR 1001-14

Air Quality Control Commission

The analytical methods to be employed for the determination of ambient

air concentrations of sulfur dioxide shall be any reference method

identified in title 40 CFR, Part 50, Appendix A. Alternative methods may be

used listed as a “reference” or “equivalent” method by the U.S.

Environmental Protection Agency in accordance with Title 40 CFR, Part

53. Concentrations shall be reported as micrograms per cubic meter or

parts per million referred to a temperature of 25 degrees Celsius and a

pressure of one atmosphere (1013 millibars).

1Sulfur Dioxide: Revised: 3/10/83; Effective 4/30/83. Revised 2/18/10; Effective 3/30/10.

II.

Reserved

III.

Classification of Nonattainment and Attainment/Maintenance Areas in

Colorado*

III.A. through III.E. Repealed

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Air Quality Control Commission

Area

Classification

Boundary

PM10

Denver Metro

(effective

10/16/02)

Attainment/

Maintenance

All of Denver, Jefferson, and Douglas Counties;

Boulder County (excluding Rocky Mountain

National Park) and the Automobile Inspection

and Readjustment Program portions of Adams

and Arapahoe Counties. See attached map.

Steamboat

Springs (effective

11/24/04)

Attainment

/Maintenance

Steamboat Springs Area Airshed as adopted

by the Routt County Commissioners May 28,

1991. See attached map.

Pagosa Springs

(effective

8/14/01)

Attainment/

Maintenance

See attached map.

Telluride/Mt.

Village/San

Miguel County

(effective 8/14/01)

Attainment/

Maintenance

See attached map.

Aspen/Pitkin

County (effective

7/14/03)

Attainment/

Maintenance

See attached map

/24/04)

Attainment

/Maintenance

Steamboat Springs Area Airshed as adopted

by the Routt County Commissioners May 28,

1991. See attached map.

Pagosa Springs

(effective

8/14/01)

Attainment/

Maintenance

See attached map.

Telluride/Mt.

Village/San

Miguel County

(effective 8/14/01)

Attainment/

Maintenance

See attached map.

Aspen/Pitkin

County (effective

7/14/03)

Attainment/

Maintenance

See attached map.

Cañon

City/Fremont

County

(effective 7/31/00)

Attainment/

Maintenance

See attached map.

Lamar

(effective

11/25/05)

Attainment/

Maintenance

Lamar City Limits as of July 30, 1991. See

attached map.

Ozone

Denver 1-Hour

Ozone

Attainment/Mainte

nance Area

(effective

10/11/01)

Attainment/

Maintenance

The Counties of Jefferson and Douglas, the

Cities and Counties of Denver and Broomfield,

Boulder County (excluding Rocky Mountain

National Park), Adams County west of Kiowa

Creek, and Arapahoe County west of Kiowa

Creek. See attached map.

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Air Quality Control Commission

Area

Classification

Boundary

Denver Metro

Area/North Front

Range 8-Hour

Ozone

Nonattainment

Area (effective

11/20/07)

Nonattainment

The Counties of Adams, Arapahoe, Boulder

(includes part of Rocky Mountain National

Park), Douglas, and Jefferson; the Cities and

Counties of Denver and Broomfield; and the

following portions of the Counties of Larimer

and Weld:

Larimer County (includes part of Rocky

Mountain National Park), that portion of the

county that lies south of a line described as

follows: Beginning at a point on Larimer

County’s eastern boundary and Weld County’s

western boundary intersected by 40 degrees,

42 minutes, and 47.1 seconds north latitude,

proceed west to a point defined by the

intersection of 40 degrees, 42 minutes, 47.1

seconds north latitude and 105 degrees, 29

minutes, and 40.0 seconds west longitude,

thence proceed south on 105 degrees, 29

minutes, 40.0 seconds west longitude to the

intersection with 40 degrees, 33 minutes and

17.4 seconds north latitude, thence proceed

west on 40 degrees, 33 minu

d 47.1 seconds north latitude,

proceed west to a point defined by the

intersection of 40 degrees, 42 minutes, 47.1

seconds north latitude and 105 degrees, 29

minutes, and 40.0 seconds west longitude,

thence proceed south on 105 degrees, 29

minutes, 40.0 seconds west longitude to the

intersection with 40 degrees, 33 minutes and

17.4 seconds north latitude, thence proceed

west on 40 degrees, 33 minutes, 17.4 seconds

north latitude until this line intersects Larimer

County’s western boundary and Grand

County’s eastern boundary.

Weld County, that portion of the county that lies

south of a line described as follows: Beginning

at a point on Weld County’s eastern boundary

and Logan County’s western boundary

intersected by 40 degrees, 42 minutes, 47.1

seconds north latitude, proceed west on 40

degrees, 42 minutes, 47.1 seconds north

latitude until this line intersects Weld County’s

western boundary and Larimer County’s

eastern boundary.

See attached map.

* The classification of the Denver Metro Area as an attainment/maintenance area shall not affect Air Quality Control Commission

Regulations Number 1, 5 CCR 1001-3, Section VIII; or Number 3, 5 CCR 1001-5, Part B, Section IV.D.2.(d)(i) or (ii). Such provisions

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Air Quality Control Commission

shall apply in the Denver Metro Area in the same manner as they would apply if the Denver Metro Area were nonattainment area for

PM10.

III.F.

Denver PM10 and 1-Hour Ozone Attainment/Maintenance Area

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III.G. Steamboat Springs Attainment/Maintenance Area for PM10

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III.H. Pagosa Springs Attainment/Maintenance Area for PM10

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III.I.

Telluride/Mt. Village/San Miguel County Attainment/Maintenance Area for

PM10

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/Maintenance Area for PM10

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III.H. Pagosa Springs Attainment/Maintenance Area for PM10

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Air Quality Control Commission

III.I.

Telluride/Mt. Village/San Miguel County Attainment/Maintenance Area for

PM10

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Air Quality Control Commission

III.J. Aspen/Pitkin County Attainment/Maintenance Area for PM10

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Air Quality Control Commission

III.K. Cañon City/Fremont County Attainment/Maintenance Area for PM10

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III.L. Lamar Attainment/Maintenance Area for PM10

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III.M. Denver Metro Area/North Front Range 8-Hour Ozone Nonattainment Area,

2008 Ozone National Ambient Air Quality Standard

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III.N. Denver Metro Area/North Front Range and northern Weld County 8-Hour

Ozone Nonattainment Area, 2015 Ozone National Ambient Air Quality Standard

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IV.

Visibility Standard

To be added to the Colorado Air Quality Control Commission document “Ambient Air

Standards for Metropolitan Denver Air Quality Control Region, State Air Pollution

Control Areas and the State of Colorado.”

Visibility Standard for the AIR Program Area

Level: The Visibility Standard for the AIR program area is an atmospheric extinction

of.076/km 1, equivalent to a standard visual range of 32 miles2

Averaging Time: The Averaging time is four hours. All four hours must be contiguous

tandards for Metropolitan Denver Air Quality Control Region, State Air Pollution

Control Areas and the State of Colorado.”

Visibility Standard for the AIR Program Area

Level: The Visibility Standard for the AIR program area is an atmospheric extinction

of.076/km 1, equivalent to a standard visual range of 32 miles2

Averaging Time: The Averaging time is four hours. All four hours must be contiguous.

No four-hour average in violation of the standard can have hours in common with any

other four-hour period in violation of the standard.3

Applicability: The visibility standard is applicable in the AIR program area.4 The visibility

standard applies during an eight-hour period from 8:00 a.m. (0800) to 4:00 p.m. (1600)

each day Mountain Local Time. The visibility standard applies only during hours when

the hourly average relative humidity is less than 70 percent.5

1Extinction is a measure of the ability of the atmosphere to attenuate light. It is traditionally expressed in light attenuation per

kilometer. It is measured directly with a long-path transmissometer or by other equivalent methods as determined by the Air Pollution

Control Division.

2Extinction (Bext) can be converted to standard visual range (SVR) in miles as follows:

SVR (Miles) = (3.912/(Bext +.01 km))*.06214

Where Bray is the Rayleigh scattering coefficient (.0099/km) for Denver's altitude and the visual range is standardized to a Rayleigh

scattering coefficient of.01/km or an altitude of 1.55km. The formula assumes a contrast threshold of two percent.

3There are five possible contiguous four-hour periods from 0800 to 1600 each day (0800 to 1200, 0900 to 1300, 1000 to 1500, and

1200 to 1600). Only the periods from 0800 to 1200 and from 1200 to 1600 do not have overlapping hours. Therefore, a maximum of

two standard violations are possible each day that have no overlapping hours or hours in common.

4The AIR program area is defined in C.R.S. 42-4-307 (8)

are five possible contiguous four-hour periods from 0800 to 1600 each day (0800 to 1200, 0900 to 1300, 1000 to 1500, and

1200 to 1600). Only the periods from 0800 to 1200 and from 1200 to 1600 do not have overlapping hours. Therefore, a maximum of

two standard violations are possible each day that have no overlapping hours or hours in common.

4The AIR program area is defined in C.R.S. 42-4-307 (8).

5Any hour with a relative humidity of 70 percent or over would not be included in the four-hour running averages.

* Visibility: Adopted: 12/21/89; Effective: 1/1/95

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Air Quality Control Commission

Emission Budgets for Attainment/Maintenance Areas in the State of

Colorado

V.A.

Budgets

V.A.1. The following Motor Vehicle Emission Budgets shall be utilized to assess the

conformity of Transportation Plans, TIPs, and where appropriate, Projects, for the

applicable periods and geographic areas indicated:

Denver Attainment/Maintenance Area

(Modeling Domain)

PM10: 2015 through 2021: 54 tons/day;

2022 and beyond: 55 tons/day.

Nitrogen Oxides: 2015 through 2021: 70

tons/day; 2022 and beyond: 56 tons/day

Trading provisions: Trading of PM10 for

NOx, or NOx for PM10 to adjust

emission budgets for purposes of

demonstrating transportation conformity

shall be allowed using the emission

trading formula as follows:

For trades necessary to increase a

primary PM10 budget, 15.0 tons/day of

NOx will be taken from the NOx budget

to increase the primary PM10 budget by

1.0 tons/day, a ration of 15 to 1.

For trades necessary to increase a NOx

budget, 1.0 tons/day of primary PM10

will be taken from the primary PM10

budget to increase the NOx budget by

12.0 tons/day, a ratio of 1 to 12.

Implementation of trading provisions: In

the event the MPO cannot demonstrate

consistency with the specific PM10 and

NOx mobile source emission budgets,

the trading provisions may be utilized

only after the MPO has considered all

reasonably available local control

measures to meet the budgets

ll be taken from the primary PM10

budget to increase the NOx budget by

12.0 tons/day, a ratio of 1 to 12.

Implementation of trading provisions: In

the event the MPO cannot demonstrate

consistency with the specific PM10 and

NOx mobile source emission budgets,

the trading provisions may be utilized

only after the MPO has considered all

reasonably available local control

measures to meet the budgets. The

MPO must demonstrate the need for

trading through the usual consultation

procedures for state implementation

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Air Quality Control Commission

plan development delineated in Section

IV (F) of AQCC Regulation Number 10,

Criteria for Analysis of Conformity.

If trading is utilized, the MPO shall

include the following information in the

transportation conformity determination:

The budget for primary PM10

and NOx for each required year of

the conformity determination, before

trading is employed; (2) The portion

of the original budget to be used to

supplement a wanting budget, for

each required year for the

conformity determination; (3) The

increased budget that results from

trading, along with relevant

calculations, and (4) the resulting

primary PM10 and NOx budgets for

each required year of the conformity

demonstration.

The MPO shall then compare projected

emissions to the adjusted PM10 and

NOx motor vehicle emission budgets to

demonstrate conformity.

Denver Attainment/Maintenance Area

Ozone Precursors

(attainment/maintenance area

boundary) NOx 2002 and beyond 134

tpsd VOC 2002 and beyond 119 tpsd

(tpsd = tons per summer day

Denver Metro Area/North Front Range

8-Hour Ozone Moderate

Nonattainment Area (for the 1997 8-

Hour Ozone NAAQS; to be superseded

by the emissions budgets associated

with the 2008 8-Hour Ozone NAAQS

upon the effective date of EPA’s

Regional Emissions Budgets

NOx: 122.9 tons/day

VOCs: 109.2 tons/day

Southern Sub-Regional Emissions

Budgets

NOx: 102.4 tons/day

Adopted 2008, 1997

Ozone NAAQS

er day

Denver Metro Area/North Front Range

8-Hour Ozone Moderate

Nonattainment Area (for the 1997 8-

Hour Ozone NAAQS; to be superseded

by the emissions budgets associated

with the 2008 8-Hour Ozone NAAQS

upon the effective date of EPA’s

Regional Emissions Budgets

NOx: 122.9 tons/day

VOCs: 109.2 tons/day

Southern Sub-Regional Emissions

Budgets

NOx: 102.4 tons/day

Adopted 2008, 1997

Ozone NAAQS

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Air Quality Control Commission

determination of adequacy for

transportation conformity purposes)

(State Only)

VOCs: 89.7 tons/day

Northern Sub-Regional Emissions

Budgets

NOx: 20.5 tons/day

VOCs: 19.5 tons/day

Denver Metro Area/North Front Range

8-Hour Ozone Nonattainment Area (for

the 2008 8-Hour Ozone NAAQS; these

emissions budgets will supersede the

previous emissions budgets upon the

effective date of EPA’s determination

of adequacy for transportation

conformity purposes)

Regional Emissions Budgets

NOx: 73 tons/day

VOCs: 55 tons/day

Southern Sub-Regional Emissions

Budgets

NOx: 61 tons/day

VOCs: 47 tons/day

Northern Sub-Regional Emissions

Budgets

NOx: 12 tons/day

VOCs: 8 tons/day

Adopted 2016, 2008

Ozone NAAQS,

Moderate SIP

Denver Metro Area/North Front Range

8-Hour Ozone Serious Nonattainment

Area (for the 2008 8-Hour Ozone

NAAQS; these emissions budgets will

supersede the previous emissions

budgets upon the effective date of

EPA’s determination of adequacy for

transportation conformity purposes)

(State Only)

Regional Emissions Budgets

NOx: 54.7 tons/day

VOCs: 49.4 tons/day

Southern Sub-Regional Emissions

Budgets

NOx: 45 tons/day

VOCs: 41.2 tons/day

Northern Sub-Regional Emissions

Budgets

NOx: 9.7 tons/day

VOCs: 8.2 tons/day

Adopted 2020, 2008

Ozone NAAQS,

Serious SIP

Denver Metro Area/North Front Range

8-Hour Ozone Nonattainment Area (for

the 2008 8-Hour Ozone NAAQS; these

emissions budgets will supersede the

previous emissions budgets upon the

effective date of EPA’s determination

of adequacy for transportation

Regional Emissions Budgets

NOx: 21.7 tons

gional Emissions

Budgets

NOx: 9.7 tons/day

VOCs: 8.2 tons/day

Adopted 2020, 2008

Ozone NAAQS,

Serious SIP

Denver Metro Area/North Front Range

8-Hour Ozone Nonattainment Area (for

the 2008 8-Hour Ozone NAAQS; these

emissions budgets will supersede the

previous emissions budgets upon the

effective date of EPA’s determination

of adequacy for transportation

Regional Emissions Budgets

NOx: 21.7 tons/day

VOCs: 27.0 tons/day

Southern Sub-Regional Emissions

Budgets

NOx: 18.3 tons/day

VOCs: 23.0 tons/day

Adopted 2023, 2008

Ozone NAAQS,

Severe SIP

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Air Quality Control Commission

conformity purposes)

Northern Sub-Regional Emissions

Budgets

NOx: 3.4 tons/day

VOCs: 4.0 tons/day

Denver Metro Area/North Front Range

and northern Weld County Ozone

Nonattainment Area (for the 2015 8-

Hour Ozone NAAQS; these emissions

budgets will supersede the previous

emissions budgets upon the effective

date of EPA’s determination of

adequacy for transportation conformity

purposes)

Regional Emissions Budgets

NOx: 31.6 tons/day

VOCs: 35.2 tons/day

Southern Sub-Regional Emissions

Budgets

NOx: 26.8 tons/day

VOCs: 30.0 tons/day

Northern Sub-Regional Emissions

Budgets

NOx: 4.8 tons/day

VOCs: 5.2 tons/day

Adopted 2022, 2015

Ozone NAAQS,

Moderate SIP

Denver Metro Area/North Front Range

and northern Weld County Ozone

Nonattainment Area (for the 2015 8-

Hour Ozone NAAQS; these emissions

budgets will supersede the previous

emissions budgets upon the effective

date of EPA’s determination of

adequacy for transportation conformity

purposes)

Regional Emissions Budgets

NOx: 28.8 tons/day

VOCs: 27.2 tons/day

Southern Sub-Regional Emissions

Budgets

NOx: 24.8 tons/day

VOCs: 23.2 tons/day

Northern Sub-Regional Emissions

Budgets

NOx: 3.9 tons/day

VOCs: 4.0 tons/day

Adopted 2025, 2015

Ozone NAAQS,

Serious SIP

Aspen Attainment/Maintenance Area

PM10 2023 and Beyond: 1,146 lbs./day

Cañon City

PM10 2020 and Beyond: 1,613 lbs./day

Lamar (Modeling Area)

PM10 2025 and Beyond: 764 lbs./day

VOCs: 27.2 tons/day

Southern Sub-Regional Emissions

Budgets

NOx: 24.8 tons/day

VOCs: 23.2 tons/day

Northern Sub-Regional Emissions

Budgets

NOx: 3.9 tons/day

VOCs: 4.0 tons/day

Adopted 2025, 2015

Ozone NAAQS,

Serious SIP

Aspen Attainment/Maintenance Area

PM10 2023 and Beyond: 1,146 lbs./day

Cañon City

PM10 2020 and Beyond: 1,613 lbs./day

Lamar (Modeling Area)

PM10 2025 and Beyond: 764 lbs./day

Pagosa Springs (Modeling Area)

PM10 2021 and Beyond: 946 lbs./day

Steamboat Springs (Modeling Area)

PM10 2015 through 2023: 21,773

lbs./day

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Air Quality Control Commission

PM10 2024 and Beyond: 1,103.2

lbs./day

Telluride (Modeling Area)

PM10 2021 and Beyond: 1,008 lbs./day

V.A.2. Geographic Coverage

Unless otherwise specified, the geographic coverage of each of the area Motor

Vehicle Emissions Budgets shall be the nonattainment or attainment

maintenance area as defined in the respective state implementation plans.

V.A.3. The Motor Vehicle Emissions Budget for PM10 applies to total primary PM10

emissions, including emissions from tailpipe exhaust, unpaved roads (except for

the Denver PM10 nonattainment area), re-entrained road dust and street sand. It

does not include precursor or secondary emissions, which, where appropriate,

are covered under separate budgets.

V.A.4. Effective Dates

V.A.4.a.

Repealed

V.A.4.b.

Repealed

V.A.4.c.

Reserved

V.A.4.d.

Reserved

V.A.4.e.

total primary PM10

emissions, including emissions from tailpipe exhaust, unpaved roads (except for

the Denver PM10 nonattainment area), re-entrained road dust and street sand. It

does not include precursor or secondary emissions, which, where appropriate,

are covered under separate budgets.

V.A.4. Effective Dates

V.A.4.a.

Repealed

V.A.4.b.

Repealed

V.A.4.c.

Reserved

V.A.4.d.

Reserved

V.A.4.e.

Aspen PM10

The 16,244 pounds-per-day PM10 emission budget established in Section

V.A.1. shall take effect as a matter of state law when such budget takes

effect as a matter of federal law pursuant to 40 CFR Section 93.118. Until

such time as the 16,244 pounds-per-day budget takes effect pursuant to

this section and 40 CFR Section 93.118, the PM10 emission budget for

the Aspen PM10 Nonattainment Area shall be 13,974 pounds-per-day.

V.A.4.f.

Pagosa Springs PM10

The 946 pounds-per-day PM10 emission budget established in Section

V.A.1. shall take effect as a matter of state law when budget takes effect

as a matter of federal law pursuant to 40 CFR Section 93.118. Until such

time as the 946 pounds-per-day budget takes effect pursuant to this

section and 40 CFR Section 93.118, the PM10 emission budget for the

Pagosa Springs PM10 attainment/maintenance area shall be 7,486

pounds-per-day.

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V.A.4.g.

Cañon City PM10

The 1,613 pounds-per-day PM10 emission budget established in Section

V.A.1. shall take effect as a matter of state law when such budget takes

effect as a matter of federal law pursuant to 40 CFR Section 93.118. Until

such time as the 1,613 pounds-per-day budget takes effect pursuant to

this section and 40 CFR section 93.118, the PM10 emission budget for the

Cañon City PM10 attainment/maintenance area shall be 7,439 pounds-

per-day.

V.A.4.h.

Lamar PM10

The 764 pounds-per-day PM10 emission budget established in Section

V.A.1

budget takes

effect as a matter of federal law pursuant to 40 CFR Section 93.118. Until

such time as the 1,613 pounds-per-day budget takes effect pursuant to

this section and 40 CFR section 93.118, the PM10 emission budget for the

Cañon City PM10 attainment/maintenance area shall be 7,439 pounds-

per-day.

V.A.4.h.

Lamar PM10

The 764 pounds-per-day PM10 emission budget established in Section

V.A.1. shall take effect as a matter of state law when such budget takes

effect as a matter of federal law pursuant to 40 CFR Section 93.118. Until

such time as the 764 pounds-per-day budget takes effect pursuant to this

section and 40 CFR Section 93.118, the PM10 emission budget for the

Lamar PM10 Nonattainment Area shall be 7,534 pounds-per-day.

V.A.4.i.

Steamboat Springs PM10

The 21,773 pounds-per-day PM10 emission budget established in Section

V.A.1. shall take effect as a matter of state law when such budget takes

effect as a matter of federal law pursuant to 40 CFR Section 93.118. Until

such time as the 21,773 pounds-per-day budget takes effect pursuant to

this section and 40 CFR Section 93.118, the PM10 emission budget for

the Steamboat Springs PM10 Nonattainment Area shall be 20,682

pounds-per-day.

V.A.4.j.

Telluride PM10

The 1,108 pounds-per-day PM10 emission budget established in Section

V.a.1. shall take effect as a matter of state law when such budget takes

effect as a matter of federal law pursuant to 40 CFR Section 93.118. Until

such time as the 1,108 pounds-per-day budget takes effect pursuant to

this section and 40 CFR Section 93.118, the PM10 emission budget for

the Telluride PM10 Attainment Area shall be 10,001 pounds-per-day (2012

and beyond).

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law when such budget takes

effect as a matter of federal law pursuant to 40 CFR Section 93.118. Until

such time as the 1,108 pounds-per-day budget takes effect pursuant to

this section and 40 CFR Section 93.118, the PM10 emission budget for

the Telluride PM10 Attainment Area shall be 10,001 pounds-per-day (2012

and beyond).

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Air Quality Control Commission

V.B.

Reserved

V.C.

Additional Requirements for the Denver PM10 Attainment/Maintenance

Area

V.C.1. Geographic Coverage

The geographic coverage for the Denver PM10 Motor Vehicle Emissions Budget

is the modeling domain contained in the most recent revision to the Denver

PM10 state implementation plan and technical support documentation, which are

available for inspection at the offices of the AQCC located at 4300 Cherry Creek

Drive South, Denver, Colorado.

V.C.2. Regional Emissions Analysis

The emissions budgets set out in this section shall be used for regional

emissions analyses required for conformity determinations.

V.D.

Repealed

VI.

Carbon Monoxide Standard within the Eisenhower Tunnel* (State Only)

Pursuant to the authority of § 25-7-106 (1), (b) and (c) and of 25-7-107 (1), (a), and (b)

of Colorado Revised Statutes 1973, the Colorado Air Quality Control Commission

designated and confines of any traveled portions of the roadways within the Eisenhower

Tunnel as a control area in which the adoption and maintenance of an ambient air

standard is deemed necessary with particular identification of “carbon monoxide” as the

pollutant hereby made subject to the following standard to maintain an acceptable

human carboxyhemoglobin level: the ambient air within the Eisenhower Tunnel shall be

maintained so that the levels of carbon monoxide shall not exceed a 15 minute average

of 100 parts per million volume (115 milligrams per cubic meter at 760 Torr and 25

degrees Celsius) concentration.

* Carbon Monoxide/Eisenhower Tunnel: Adopted: 9/5/75 Effective: 12/17/75

Method of Testing:

intain an acceptable

human carboxyhemoglobin level: the ambient air within the Eisenhower Tunnel shall be

maintained so that the levels of carbon monoxide shall not exceed a 15 minute average

of 100 parts per million volume (115 milligrams per cubic meter at 760 Torr and 25

degrees Celsius) concentration.

* Carbon Monoxide/Eisenhower Tunnel: Adopted: 9/5/75 Effective: 12/17/75

Method of Testing:

1. For the purpose of this regulation, primary determinations of CO

shall be made by use of instrumentation based on non-

dispersive infrared spectrophotometry (NDIR), as specified in

Federal Register, 36 (84), 8194-8195 (30 April, 1971), Appendix

C. Other methods equivalent, in accuracy, precision, and

freedom from interferences may be used if approved in advance

by the Air Pollution Control Division.

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Routine monitoring of CO may be performed by instruments based on other

principles, provided that such instruments are demonstrated to yield results

equivalent to measurements by NDIR. methods, within the limits of accuracy and

precision approved in advance by the Air Pollution Control Division.

Instruments used for primary determinations and routine monitoring shall be

maintained to at least the minimum standards recommended by their

manufacturers. Calibrations shall be made at the location of use according to the

procedures set out in “Guidelines for Development of a Quality Assurance

Program: Reference Method for the “Continuous Measurement of Carbon

Monoxide in the Atmosphere” , EPA-R4-028A, June 1973, pp. 8-20.

Records of maintenance and calibrations of all instruments shall be kept in a

current, timely manner. The sources and identifications of gas mixtures used in

calibrations shall be entered in records of calibration. These records of calibration

and summaries of operating CO levels shall be made available within 30 days

after the end of the calendar quarter to the Air Pollution Control Division for

review.

of maintenance and calibrations of all instruments shall be kept in a

current, timely manner. The sources and identifications of gas mixtures used in

calibrations shall be entered in records of calibration. These records of calibration

and summaries of operating CO levels shall be made available within 30 days

after the end of the calendar quarter to the Air Pollution Control Division for

review.

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VII.

Rationale

VII.A. Rationale for the Promulgation of Ambient Air Quality Standards for Sulfur

Dioxide

The Commission's review of the large volume of scientific data presented at the

hearings led to several conclusions relevant to the establishment of appropriate ambient

air quality standards for the State of Colorado. Sulfur dioxide is a colorless, irritating gas

with a taste threshold on the order of 600 to 800 micrograms per cubic meter and an

odor threshold approximately twice that value. It is converted in the atmosphere (at a

presently undetermined rate) into particulate sulfuric acid droplets, and solid metallic

sulfates. The hazards to human health of such sulfates are presently under extensive

investigation by EPA and a broad section of the scientific community.

This Commission has not considered the question of health impacts of particulate

surfaces in its adoption of ambient air standards for Colorado except to note that the

information available is often conflicting and confusing. The same remarks are

applicable to the effect of particulate sulfates on visibility. The Commission is very much

aware that many have questioned the validity of EPA primary and secondary sulfur

dioxide standards to protect humans, and animals, and vegetation with regard to (a)

long term exposure to low concentrations of sulfur dioxide, (b) effects of altitude on

atmospheric conversion of sulfur dioxide and attendant sulfate hazards, and (c)

synergistic action of sulfur dioxide with other pollutants on vegetation

e that many have questioned the validity of EPA primary and secondary sulfur

dioxide standards to protect humans, and animals, and vegetation with regard to (a)

long term exposure to low concentrations of sulfur dioxide, (b) effects of altitude on

atmospheric conversion of sulfur dioxide and attendant sulfate hazards, and (c)

synergistic action of sulfur dioxide with other pollutants on vegetation.

The concerns of this Commission with regard to such considerations has led to the

adoption of ambient air standards more restrictive than the EPA primary and secondary

standards because: (1) the Commission is charged under the Colorado Air Pollution

Control Act of 1970 with the achievement of the maximum practical degree of air purity

throughout the State, (2) the evidence presented before this Commission and the

evaluation conducted by the Commission and its staff raises serious unanswered

questions about the possible effect of long term exposure of certain low levels of sulfur

dioxide on vegetation and on the agricultural industry in our State, (3) the Commission

desired to ensure that the policy of this State with regard to maximization of air purity

and the Federal Prevention of Significant Deterioration policies, under which Colorado

desires to seek delegation of authority, will be realized with regard to existing air quality

in Colorado for sulfur dioxide which is generally very good.

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d to ensure that the policy of this State with regard to maximization of air purity

and the Federal Prevention of Significant Deterioration policies, under which Colorado

desires to seek delegation of authority, will be realized with regard to existing air quality

in Colorado for sulfur dioxide which is generally very good.

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Under the Prevention of Significant Deterioration doctrine, EPA has adopted sulfur

dioxide ambient air quality standards in three classes. Class I preserves the pristine

quality of pristine air. Class II permits moderate deterioration, and Class III sets an

absolute limit at the Federal secondary standard (that ambient air standard designed to

protect human welfare). The evidence received by this Commission was overwhelming

in its support of the preservation of pristine conditions in National Parks, National

Monuments, Wilderness and Primitive Areas, and the Gunnison Gorge Recreation area.

It is logical to apply the EPA Prevention of Significant Deterioration Class I standards to

these regions, to protect the air quality for intrusion by external sources, and no

submission by any industrial representative in these public hearings opposed the use of

the Federal Class I standards for the areas noted above.

The Commission has discovered no adequate rationale for adoption of the (EPA) PSD

Class III standard for sulfur dioxide. This Commission questions the need for

authorization of such concentrations of sulfur dioxide in the State of Colorado. Existing

conditions in Colorado do not appear to even approach the Class in levels, and no

proposal for development, as described by industrial representatives at the hearings,

would be at all restricted by a standard more stringent than the Federal Class II

standard

fur dioxide. This Commission questions the need for

authorization of such concentrations of sulfur dioxide in the State of Colorado. Existing

conditions in Colorado do not appear to even approach the Class in levels, and no

proposal for development, as described by industrial representatives at the hearings,

would be at all restricted by a standard more stringent than the Federal Class II

standard. Therefore, Federal PSD Class II standards have been adopted as the

Colorado Category III standards: proposed development of sulfur dioxide sources as

presented to the Commission by a variety of industrial representatives, can proceed

with much less impact than the Federal Class II for sulfur dioxide would allow. The

Commission has thereby maintained consistency with Federal PSD requirements and

feels that the State will be in a position in the near future to request delegation of

authority from the Environmental Protection Agency for enforcement of PSD

requirements.

The Colorado Category I standards for sulfur dioxide effective December 18, 1975 are

very stringent ones, and because the bulk of the state is now designated as a Colorado

Category I, certain proposed industrial development, as presented before this

Commission and including energy conversion, might thereby be restricted. One

proposed solution to this problem was redesignation to the Federal (PSD) Class II for

the entire state. This concentration of sulfur dioxide. As noted above, the Commission

simply does not feel that such extreme degradation in existing air quality for sulfur

dioxide throughout the entire state is necessary. It is not necessary, according to

evidence presented to the Commission, to go to the Colorado Category II standards set

forth under the 1975 regulation to permit projected new industrial development.

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s not feel that such extreme degradation in existing air quality for sulfur

dioxide throughout the entire state is necessary. It is not necessary, according to

evidence presented to the Commission, to go to the Colorado Category II standards set

forth under the 1975 regulation to permit projected new industrial development.

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The Commission has therefore adopted a standard, which are essentially at the halfway

mark between PSD Class I and PSD Class II. This standard does allow for all the

proposed development of sulfur dioxide sources described in hearings before this

Commission and is an acceptable one to the Commission because it will not prohibit

development, with careful siting considerations, yet avoids the necessity for

redesignation involving substantial deterioration of existing air quality for sulfur dioxide.

It should be noted that, at the PSD Class II levels, many Colorado citizens might

actually be physically affected by the unpleasant and irritating taste of sulfur dioxide in

the ambient air.

All of the above-described ambient standards to be established by this Commission for

sulfur dioxide, are incremental standards. However, the Commission also feels strongly

that an absolute standard, and “under lid,” should be placed on sulfur dioxide levels as

well. It is the absolute concentration, rather than the increment, which affects human

health, welfare, and the “quality of life” which our Colorado Air Pollution Control Act so

clearly seeks to protect. In order to assure compliance with the policy of this state, this

Commission has adopted a three-hour average concentration of sulfur dioxide, of 700

micrograms per cubic meter, as an absolute standard not to be exceeded more than

once per year. This absolute standard is again related to that level of sulfur dioxide in

the ambient air, which may cause obvious physical irritation for certain Colorado

citizens

assure compliance with the policy of this state, this

Commission has adopted a three-hour average concentration of sulfur dioxide, of 700

micrograms per cubic meter, as an absolute standard not to be exceeded more than

once per year. This absolute standard is again related to that level of sulfur dioxide in

the ambient air, which may cause obvious physical irritation for certain Colorado

citizens. This Commission intends to protect those citizens and all other residents of our

State from impairment of their general welfare, convenience, and enjoyment of the

beauty of life, which Colorado has to offer.

Ambient air quality standards will play an important role in the permitting process, and

since that process involves the application of predictive modeling all incremental

standards should be considered significant only to one significant figure.

As noted above, Colorado Category I for sulfur dioxide has been designated for certain

areas based on the evidence received at public hearing. The Commission has also

provided for designation of any National Parks, Monuments, Wilderness or Primitive

Areas or Wild and Scenic River Corridors, which may be established in Colorado in the

future. Such designation will be made after Commission evaluation of the comments of

members of the public at hearing.

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The Commission, on the basis of broad support from industry and the general public,

decided not to permit redesignation of the Category I areas. The Commission found that

sufficient documentation should accompany a redesignation request to show that the

request is serious, well thought out in its various implications, and has some public

support. On the basis of considerable testimony, it also developed a set of criteria by

which the redesignation request will be judged. The Commission thus concluded that all

of these elements in the redesignation process must be met before the designation is

granted.

VII.B

redesignation request to show that the

request is serious, well thought out in its various implications, and has some public

support. On the basis of considerable testimony, it also developed a set of criteria by

which the redesignation request will be judged. The Commission thus concluded that all

of these elements in the redesignation process must be met before the designation is

granted.

VII.B. Rationale and Justification for Revision to the Ambient Air Quality Standards for

Sulfur Dioxide Regarding the Method of Testing and Reporting (Section C)

This action brings the State of Colorado regulations into conformity with the Federal

regulations for (a) the methods for measurements of ambient concentrations of sulfur

dioxide and (b) the manner in which these concentrations are reported:

This question as to whether these concentrations should be expressed in (a)

micrograms per actual cubic meter or (b) micrograms per standard cubic meter (at 25

degrees Celsius and one atmosphere) is not resolved. If the hazard is related to the

ratio of sulfur dioxide to oxygen the standard cubic meter concentration is preferable. If

the concentrations are expressed in micrograms per standard cubic meter, the

equivalent expression in parts per million is independent of altitude and temperature;

this is not true if the concentrations are given in micrograms per actual cubic meter. The

deciding issue in the decision was conformity with Federal Standards.

VII.C. Rationale and Justification for the Repeal and Readoption of Ambient Air Quality

Standards for Total Suspended Particulates*

This action brings the State of Colorado Ambient Air Quality Standards for Total

Suspended Particulates into conformity with the existing Federal Ambient Air Quality

Standards for Total Suspended Particulates, and are the same standards, which are

required to be met by 1982 by the Clean Air Act (1977 Amendments) and the Colorado

State Implementation Plan

Standards for Total Suspended Particulates*

This action brings the State of Colorado Ambient Air Quality Standards for Total

Suspended Particulates into conformity with the existing Federal Ambient Air Quality

Standards for Total Suspended Particulates, and are the same standards, which are

required to be met by 1982 by the Clean Air Act (1977 Amendments) and the Colorado

State Implementation Plan.

Ambient Air Quality Standards play an important role in determining various aspects of

the State air pollution permitting process and thus the adoption of State Ambient Air

Quality Standards for Total Suspended Particulates identical to the Federal standards

subject’s applicants for an emission permit to only one standard, rather than different

State and Federal Standard

The deciding issues in the decision were conformity with Federal standards and great

public understanding.

* Rationale/TSP – Repeal and Readoption: Adopted 4/12/79

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VIII.

Statements of Basis, Specific Statutory Authority and Purpose

VIII.A. Emission Budgets for Nonattainment Areas in the State of Colorado

Adopted: February 16, 1995

Section 176(c) of the Federal Clean Air Act Amendments of 1990 requires that

transportation plans and programs adopted by a metropolitan planning organization

conform to the appropriate state implementation plan. Pursuant to EPA regulations

implementing Section 176(c), mobile source emissions resulting from such plans and

programs ultimately must be demonstrated, to be consistent with the motor vehicle

emissions budget set forth in the applicable SIP. Without a clearly indicated intent

otherwise, the SIP's highway and transit mobile source inventory serves as the motor

vehicle emissions budget

tation plan. Pursuant to EPA regulations

implementing Section 176(c), mobile source emissions resulting from such plans and

programs ultimately must be demonstrated, to be consistent with the motor vehicle

emissions budget set forth in the applicable SIP. Without a clearly indicated intent

otherwise, the SIP's highway and transit mobile source inventory serves as the motor

vehicle emissions budget. However, where a SIP quantifies a “safety margin” by which

emissions from all sources are less than would be consistent with attainment throughout

the region, the State may submit a SIP revision which assigns some or all of this safety

margin to the motor vehicle emissions budget for purposes of conformity

determinations.

Adoption of Mobile Source Emissions Budgets for the Denver Nonattainment

Area

PM10

The Denver PM10 SIP, which originally was submitted prior to EPA's adoption of the

conformity regulations in November 1993, does not have mobile source emissions

budgets explicitly labeled. The Denver PM10 SIP adopted by the Air Quality Control

Commission on October 20, 1994 notes the intent to establish specific mobile source

emissions budgets for both primary PM10 emissions and emissions of PM10

precursors. The Regional Air Quality Council proposed and the Air Quality Control

Commission adopted a regional PM10 emissions budget that allocates some of the

“safety margin” in regional emissions to the mobile source emissions budget for

purposes of conformity.

Establishing the Primary PM10 Budget

The attainment demonstration for the Denver PM10 SIP indicates that modeled

concentrations approaching the federal PM10 health and welfare standard are limited to

a very small portion of the Denver region centered along the 1-25 corridor generally

between Broadway and 1-70. The remainder of the region is well below the federal

standard.

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t demonstration for the Denver PM10 SIP indicates that modeled

concentrations approaching the federal PM10 health and welfare standard are limited to

a very small portion of the Denver region centered along the 1-25 corridor generally

between Broadway and 1-70. The remainder of the region is well below the federal

standard.

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Thus, while the mobile source inventory in the central Denver area is at the Maximum

consistent with meeting the health and welfare standards, on a regional basis there is a

“safety margin” by which emissions from all sources in the region are less than the total

emissions that would be consistent with attainment of the PM10 health and welfare

standard.

In order to determine how much of the regional emissions “safety margin” to assign to

the mobile source emissions budget, the RAQC used DRCOG's transportation network

as defined by the 2015 Interim Regional Transportation Plan and projections of vehicle

miles traveled (“VMT”) as the basis for the analysis in order to determine how much of

the anticipated mobile source emission growth can be accommodated in the revision

while still maintaining the federal PM10 health and welfare standard. The emissions

from the 2015 network and its resulting VMT were estimated for each modeling grid

based on the primary PM10 emissions factors for tailpipe exhaust, re-entrained road

dust and street sand used in the PM10 SIP. The resulting gridded emissions from the

network were then modeled using the same dispersion model used for the PM10 SIP.

The analysis then identified any areas where the increased emissions resulted in

predicted concentrations greater than the federal standard of 150/ugm3.

Emissions in these areas were then reduced sufficiently so that no values above the

federal standard were predicted

PM10 SIP. The resulting gridded emissions from the

network were then modeled using the same dispersion model used for the PM10 SIP.

The analysis then identified any areas where the increased emissions resulted in

predicted concentrations greater than the federal standard of 150/ugm3.

Emissions in these areas were then reduced sufficiently so that no values above the

federal standard were predicted. The sum of the total emissions in the geographic area

modeled, taking in to account emission reductions needed to assure that PM10 health

and welfare standards were met, was then established as the PM10 mobile source

emissions budget set forth in the Ambient Air Standards rule. That budget applies as a

ceiling on emissions for each identified year.

The AQCC is aware that EPA is under court order to reconsider the PM10 national

ambient air quality standard, and that EPA is actively considering revision of the particle

size indicator and mass concentration of current standard. The AQCC considers this an

interim budget that will be replaced by a 44-ton budget in 1998. This will give the AQCC

an opportunity to develop and review a long range, comprehensive air quality

management plan that will set the air quality goals and agenda for the Denver region

over the next 20 years. The AQCC anticipates that the mobile source emissions budget

in the long range, comprehensive air quality plan will not exceed 44 tons per day. The

notice for the hearing on the long range, comprehensive air quality plan will also include

a notice for rule making on the mobile source emissions budget.

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ver the next 20 years. The AQCC anticipates that the mobile source emissions budget

in the long range, comprehensive air quality plan will not exceed 44 tons per day. The

notice for the hearing on the long range, comprehensive air quality plan will also include

a notice for rule making on the mobile source emissions budget.

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Development of Control Measures

The PM10 SIP includes all control measures necessary to achieve the emissions

budget levels for 1995 through 1997 and to ensure that localized violations of the

national ambient air quality standard for PM10 will not develop prior to December 31,

1997. However, as the SIP does not extend beyond 1997, it does not include the control

measures that may be necessary to achieve later budgeted levels. Additional control

measures to reduce mobile source emissions in the years beyond 1997 must become

enforceable as set forth in the Ambient Air Standards rule before an MPO may rely on

any such reductions in assessing conformity of a future plan or program with the mobile

source emissions budgets. This will ensure that no local violations of the national

standard will result beyond 1997.

PM10 Precursors

The Motor Vehicle Emissions Budget for PM10 applies to total primary PM10 emissions

and does not include precursor or secondary emissions. A separate Motor Vehicle

Emissions Budget for emissions of nitrogen oxides as a precursor to PM10 is

established by this Regulation. Available information indicates that SO2 emissions from

mobile sources are an insignificant contributor to secondary particulate formation in the

Denver area. Therefore, a Motor Vehicle Emissions Budget for SO2 is not established

ude precursor or secondary emissions. A separate Motor Vehicle

Emissions Budget for emissions of nitrogen oxides as a precursor to PM10 is

established by this Regulation. Available information indicates that SO2 emissions from

mobile sources are an insignificant contributor to secondary particulate formation in the

Denver area. Therefore, a Motor Vehicle Emissions Budget for SO2 is not established.

Carbon Monoxide

The RAQC recommended and the AQCC adopted as the Motor Vehicle Emissions

Budget for 1995 through 1999 the Denver Nonattainment Area Carbon Monoxide (“CO”

) SIP's estimation of regional mobile source emissions that will result after

implementation of the base programs and measures set forth in Chapter V of the SIP.

These measures include 2.7% oxygenated gasoline, the first year of the Enhanced

Inspection and Maintenance Program, and the base transportation system network that

is in place or will be completed by 1995. For purposes of determining conformity, the

budget of 1125 tons per day will remain in effect until the attainment budget takes effect

in 2000.

The RAQC recommended establishing the CO mobile source emissions budget for the

year 2000 and beyond at 825 tons per day, the level of emissions necessary to

demonstrate attainment of the federal CO standard. The AQCC chose to adopt a budget

of 808 tons per day when the Denver CO SIP was adopted on June 16, 1994. As part of

this Regulation, the RAQC and DRCOG recommended adoption of the originally

recommended CO Mobile Vehicle Emissions Budget of 825 tons per day.

Statutory Authority

The specific statutory authority for this rule is set out at § 25-7-105(1)(a), C.R.S.

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tons per day when the Denver CO SIP was adopted on June 16, 1994. As part of

this Regulation, the RAQC and DRCOG recommended adoption of the originally

recommended CO Mobile Vehicle Emissions Budget of 825 tons per day.

Statutory Authority

The specific statutory authority for this rule is set out at § 25-7-105(1)(a), C.R.S.

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VIII.B. Ozone Redesignation and the Adoption of the Mobile Source Emissions Budgets

for Ozone Precursors: VOC and NOX

Adopted: March 21, 1996

The Denver metropolitan area was designated as nonattainment area by the EPA in

1978 for violations of the Ozone National Ambient Air Quality Standard (NAAQS).

Pursuant to 185A of the 1990 amendments to the federal Clean Air Act (CAA), the

Denver Metro Area was classified as a transitional nonattainment area. The Denver

metropolitan area has demonstrated through quality-assured, monitored data from 1993

through 1995 that it has attained the ozone NAAQS. The Regional Air Quality Council

has compiled the documentation required by Section 107(d)(3)(E) of the CAA to request

redesignation to attainment status.

Included in the requirement for redesignation is a fully approved Maintenance Plan that

meets Section 175A of the CAA. Upon approval by the EPA, the Maintenance Plan will

become an element of the Colorado State Implementation Plan. The maintenance

demonstration was based on future inventories that assumed the continuance of

existing VOC controls in the Denver metro area. Such controls include the continued

application of Regulation Number 7 to the Denver area.

Federal law does not require the redesignation of the Denver nonattainment area.

However, such redesignation is required by state law. § 25-7-107(2.5). The changes to

the Ambient Air Quality Standard regulation are consistent with continued maintenance

of the ozone standard and are not otherwise more stringent than the relevant federal

requirements

cation of Regulation Number 7 to the Denver area.

Federal law does not require the redesignation of the Denver nonattainment area.

However, such redesignation is required by state law. § 25-7-107(2.5). The changes to

the Ambient Air Quality Standard regulation are consistent with continued maintenance

of the ozone standard and are not otherwise more stringent than the relevant federal

requirements.

Classification of the Denver metropolitan area

Upon redesignation by the EPA, the classification of the Denver metro area will change

from “transitional” to “attainment” for the ozone NAAQS. The Regional Air Quality

Council recommended and the Commission adopted a change in classification for the

Denver Metro area to attainment maintenance reflecting this change in status. In

addition the boundaries of the attainment maintenance are redefined and a map

depicting the boundaries is noted. The boundaries and map are the same as the

present Denver metro nonattainment area. The specific statutory authority to

redesignate the area is set out in §§ 25-7-105(1)(a)(I) and (2), -106(1)(a); -107(1) and

(2.5); and 25-7-301.

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Adoption of mobile source emissions budgets

Section 176(c) of the CAA requires that transportation plans and programs adopted by a

metropolitan planning organization conform to the appropriate state implementation

plan. Pursuant to EPA regulations implementing Section 176(c), mobile source

emissions resulting from such plans and programs ultimately mus2 be consistent with

the motor vehicle emissions budget set forth in the applicable SIP.

Without clearly indicated intent otherwise, the SIP's highway and transit mobile source

inventory serves as the motor vehicle emissions budget

opriate state implementation

plan. Pursuant to EPA regulations implementing Section 176(c), mobile source

emissions resulting from such plans and programs ultimately mus2 be consistent with

the motor vehicle emissions budget set forth in the applicable SIP.

Without clearly indicated intent otherwise, the SIP's highway and transit mobile source

inventory serves as the motor vehicle emissions budget. However, where a SIP

quantifies a “safety margin” by which emissions from all sources are less than would be

consistent with attainment throughout the region, the state may submit a SIP revision

which assigns some or all of this safety margin to the motor vehicle emissions budget

for the purposed of conformity determinations.

The most recent revisions to the Denver Ozone SIP were submitted in 1989 and 1990,

which was prior to EPA's adoption of the conformity regulations in November 1993, and

those revisions did not include explicitly labeled mobile source emissions budgets. The

Denver Ozone Maintenance Plan adopted March 21, 1996 notes the intent to establish

specific mobile source emissions budgets for the two ozone precursor gases, volatile

organic compounds (VOC) and nitrogen oxides (NOx).

The Regional Air Quality Council proposed, and the Commission adopted regional VOC

and NOx emissions budgets as provide in the rule. Such budgets allocate the “safety

margin” in regional emissions to the mobile source emissions budget for purposes of

conformity. The specific statutory authority to establish such budgets is set out in §25-7-

105(1)(a)(I).

Establishing ozone precursor budgets

The attainment demonstration is based on monitored data, which demonstrates

attainment of the NAAQS during the three-year period, 1993-95. The attainment

inventory is the baseline VOC and NOx inventory calculated for the 1993 year

ons budget for purposes of

conformity. The specific statutory authority to establish such budgets is set out in §25-7-

105(1)(a)(I).

Establishing ozone precursor budgets

The attainment demonstration is based on monitored data, which demonstrates

attainment of the NAAQS during the three-year period, 1993-95. The attainment

inventory is the baseline VOC and NOx inventory calculated for the 1993 year. The

maintenance demonstration for the Denver Ozone Maintenance Plan is based on the

future projected VOC and NOx maintenance year (2010) inventory being less than or

equal to the respective, VOC or NOx attainment year (1993) inventory. The projected

2010 inventories take into account projected growth, existing state and local control

strategies and additional federal measures and standards mandated by the Clean Air

Act Amendments of 1990.

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The total 2010 inventory for either precursor does not exceed the total 1993 inventory,

therefore demonstrating maintenance of the NAAQS through the year 2010. Then

inventory provides a “margin of safety”, since the 2010 VOC inventory is about 33 tons

per day less than the 1993 attainment inventory and the 2010 NOx inventory is about 14

tons per day less than the 1993 attainment inventory.

The emissions budget applies as a ceiling on emission in the year for which it is defined

and for all subsequent years until another milestone year for which a different budget is

defined.

Adopted ozone precursor budgets

The Regional Air Quality Council recommended that the Commission adopt mobile

source emission budgets for ozone precursors, VOC and NOx to include the available

safety margin in 1993 and in 2010 and beyond.

The adopted mobile source emissions budget is 124 tons per day for VOC in 1993 and

2010 and beyond. For NOx the budget is 139 tons per day for 1993, and 135 tons per

day is adopted for 2010 and beyond.

Findings required pursuant to

§ 25-7-110.8

The Commission determines that:

emission budgets for ozone precursors, VOC and NOx to include the available

safety margin in 1993 and in 2010 and beyond.

The adopted mobile source emissions budget is 124 tons per day for VOC in 1993 and

2010 and beyond. For NOx the budget is 139 tons per day for 1993, and 135 tons per

day is adopted for 2010 and beyond.

Findings required pursuant to

§ 25-7-110.8

The Commission determines that:

The emission inventory and the maintenance demonstration that support

the redesignation request are based on reasonably available, validated

and sound scientific methodologies. Such inventory and maintenance

demonstration were prepared by the Regional Air Quality Council and

have been reviewed by the Division. Any validated and sound scientific

methodologies and information made available by interested parties has

been considered.

The rule is administrative in nature in that it redesignates the area as an

attainment maintenance area, and will not result in any further reduction in

air pollution beyond those reductions that are currently being achieved.

The alternative chosen by the Commission is the most cost-effective,

provides the regulated community flexibility, and achieves the necessary

reduction in air pollution.

The alternative chosen by the Commission will maximize the air quality

benefits in the most cost-effective manner.

VIII.C. Redesignation of the Greeley Carbon Monoxide Nonattainment Area to

Attainment/Maintenance

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fective,

provides the regulated community flexibility, and achieves the necessary

reduction in air pollution.

The alternative chosen by the Commission will maximize the air quality

benefits in the most cost-effective manner.

VIII.C. Redesignation of the Greeley Carbon Monoxide Nonattainment Area to

Attainment/Maintenance

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Adopted September 19,1996

This Statement of Basis, Specific Statutory Authority and Purpose complies with the

requirements of the Administrative Procedures Act, § 24-4-103, C.R.S., and the

Colorado Air Pollution Prevention and Control Act, § 25-7-110.5, C.R.S.

Basis

Greeley carbon monoxide (CO) nonattainment area has not exceeded the National

Ambient Air Quality Standards for CO since 1988. Therefore, the area is eligible for

redesignation to attainment status under Section 107 of the federal Clean Air Act. The

State of Colorado is formally requesting redesignation, and the adopted redesignation

request and maintenance plan for the area will become part of the State Implementation

Plan (SIP) upon approval by the U.S. Environmental Protection Agency. The Ambient

Air Quality Standards for the State of Colorado regulation must be revised to reflect the

requested redesignation.

Statutory Authority

Specific authorities for revising the Ambient Air Quality Standards rule to reclassify the

area to attainment are contained in the Colorado Air Pollution Prevention and Control

Act, §§ 25-7-105 (1) and (2), 25-7-106(1)(a), and 25-7-107(1), (2.5), and (4). Additional

authorities are contained in §§ 25-7-302 regarding SIP contents and 25-7-109 (2)(c)

regarding the authority to regulate CO.

Purpose

The revisions to the Ambient Air Quality Standards regulation will implement the

redesignation of the Greeley CO nonattainment area to attainment. The rule revisions

become effective upon EPA's approval of the redesignation request and the

accompanying maintenance plan

uthorities are contained in §§ 25-7-302 regarding SIP contents and 25-7-109 (2)(c)

regarding the authority to regulate CO.

Purpose

The revisions to the Ambient Air Quality Standards regulation will implement the

redesignation of the Greeley CO nonattainment area to attainment. The rule revisions

become effective upon EPA's approval of the redesignation request and the

accompanying maintenance plan. The purpose of this delay in the effective date of this

rule revision is to comply with the requirement of 175 A(c) that all applicable

nonattainment area requirements shall remain in place pending EPA approval.

The changes to the Ambient Air Quality Standards regulation are as follows:

Revise the classification of the area to “Attainment/Maintenance”; and

Update the map of the area with a more legible version (the boundaries of

the area remain unchanged).

The overall effect of these rule changes will be to relax some of the applicable

requirements for stationary source permitting and for transportation planning. These

amendments to the rules are not specifically intended to reduce air pollution and,

therefore, the findings of § 25-7-110.8(1) C.R.S. are inapplicable.

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Federal Requirements

Redesignation to an attainment area is authorized but not strictly required by the federal

Act. However, expeditious action to redesignate the area as an attainment area is

required by § 25-7-107(2.5) C.R.S. In order to be meaningful, such a redesignation

must be submitted to the EPA as a SIP revision. The rule amendments are not

otherwise more stringent than the requirements of the federal Act.

VIII.D. Steamboat Springs PM10 State Implementation Plan Element

Adopted October 17, 1996

This Statement of Basis, Specific Statutory Authority, and Purpose complies with the

requirements of the Administrative Procedures Act, § 24-4-103 C.R.S. and the Colorado

Air Pollution Prevention and Control Act, § 25-7-110.5, C.R.S

ts are not

otherwise more stringent than the requirements of the federal Act.

VIII.D. Steamboat Springs PM10 State Implementation Plan Element

Adopted October 17, 1996

This Statement of Basis, Specific Statutory Authority, and Purpose complies with the

requirements of the Administrative Procedures Act, § 24-4-103 C.R.S. and the Colorado

Air Pollution Prevention and Control Act, § 25-7-110.5, C.R.S.

Basis

Section 172 of the federal Clean Air Act requires that control measures and contingency

measures be adopted as part of nonattainment area state implementation plans. The

Colorado Attorney General's Office has determined that any emission control measure

for a nonattainment area must be adopted as a State regulation in order for the

measure to be enforceable by the State of Colorado.

The Steamboat Springs area is designated as nonattainment for fine particulate matter

(PM10). In the Steamboat Springs State Implementation Plan (SIP) Element

(September 1995), the State of Colorado committed to adopt additional control

measures that allow the area to demonstrate continued maintenance of the PM10

National Ambient Air Quality Standards (NAAQS), and contingency measures that could

be implemented in the future if the area fails to attain the PM10 NAAQS by the required

date. The State Implementation Plan-Specific Regulations for Nonattainment Areas has

been revised to include these measures. Also, the Ambient Air Quality Standards for the

State of Colorado regulation has been revised to reflect the correct name of the

nonattainment area and to include emission budgets that are utilized in transportation

planning efforts.

Statutory Authority

General authority for revising the Ambient Air Quality Standards... to change the name

of the nonattainment area and to adopt the emission budgets is contained in the

Colorado Air Pollution Prevention and Control Act, § 25-7-105 (1). General and specific

authorities for revising the SIP-Specific Regulations..

mission budgets that are utilized in transportation

planning efforts.

Statutory Authority

General authority for revising the Ambient Air Quality Standards... to change the name

of the nonattainment area and to adopt the emission budgets is contained in the

Colorado Air Pollution Prevention and Control Act, § 25-7-105 (1). General and specific

authorities for revising the SIP-Specific Regulations... to adopt the emission control

measures and the contingency measures are contained in §§ 25-7-105 (1), 25-7-

106(1)(c), and 25-7-109(1) and (2).

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Purpose

Administrative changes to the Ambient Air Quality Standards ... regulation are as

follows:

Revise the name of the nonattainment area from “Routt County” to

“Steamboat Springs” , making the regulation consistent with the

Steamboat Springs PM10 SIP Element; and

Establish PM10 mobile source emission budgets for Steamboat Springs

modeling area for the periods “1999-2001” and “2002 and Beyond” for use

in making transportation conformity determinations.

Paved road dust is a primary source of PM10 emissions in the Steamboat Springs

nonattainment area. Revisions to the

SIP-Specific Regulations ... to control paved

road dust are as follows:

The previously adopted “one percent” specification for fine materials

contained in street sand is changed to “two percent”. This change was

originally requested by the City of Steamboat Springs in order to provide

the City with the maximum flexibility for providing safe streets during

winter driving conditions. This revision will increase PM10 emissions, but

the increase is more than offset by the street sweeping activities described

below.

In order to show continued attainment and maintenance of the PM10

National Ambient Air Quality Standards (NAAQS), the City of Steamboat

Springs must increase the frequency of street sweeping on Lincoln

Avenue

providing safe streets during

winter driving conditions. This revision will increase PM10 emissions, but

the increase is more than offset by the street sweeping activities described

below.

In order to show continued attainment and maintenance of the PM10

National Ambient Air Quality Standards (NAAQS), the City of Steamboat

Springs must increase the frequency of street sweeping on Lincoln

Avenue. Sweeping must occur at least once each day following each

street sanding deployment (weather and road conditions permitting) until

the City has swept Lincoln Avenue at least four times, instead of once

after each sanding deployment as previously required. The City requested

this increase in sweeping frequency in order to compensate for increased

emissions that resulted from changing the street sand specification, and to

provide emission reductions necessary to demonstrate continued

maintenance with the PM10 NAAQS.

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Within two months following a determination that the Steamboat Springs

nonattainment area has failed to attain the PM10 NAAQS or show

reasonable further progress, the City must sweep additional sections of

Lincoln Avenue and all other City streets within a defined area of central

Steamboat Springs within four days following each street sanding

deployment (weather and road conditions permitting). This sweeping

constitutes the federally required contingency measures for the Steamboat

Springs nonattainment area.

Findings

The Air Quality Control Commission makes the following findings pursuant to C.R.S. §

25-7-110.8(1).

First, the rule revisions are based on reasonably available, validated, reviewed and

sound scientific methodologies. The emission inventories that establish the emission

budgets, and the monitoring, inventories, and dispersion modeling that indicate the

need for control measures and their effectiveness in reducing PM10 emissions, were

developed/performed in accordance with published guidance from EPA

st, the rule revisions are based on reasonably available, validated, reviewed and

sound scientific methodologies. The emission inventories that establish the emission

budgets, and the monitoring, inventories, and dispersion modeling that indicate the

need for control measures and their effectiveness in reducing PM10 emissions, were

developed/performed in accordance with published guidance from EPA. Monitoring

activities in Steamboat Springs are conducted in compliance with the EPA regulations of

40 CFR Part 58. Emission inventories were developed in accordance with EPA

guidance found in “ AP-42”, the “SIP Development Guideline Document” , and the

“Control of Open Fugitive Dust” document. Dispersion modeling using the “WYND

valley” model was performed in accordance with EPA's “Supplement B to the Guideline

on Air Quality Models”.

Second, the street sweeping revisions to the SIP-Specific Regulations ... shall result in a

demonstrable reduction in air pollution due to the removal of street sand and

background paved road dust from the streets. The amount of reductions relied upon in

the SIP Element’s attainment demonstration are supported by the EPA guidance

documents cited above. The emission budgets in the Ambient Air Quality Standards ...

regulation will result in PM10 emission reductions in the area by limiting growth from the

mobile sources sector to 2002 levels (for the purposes of “transportation conformity”

determinations - federal transportation conformity regulations of 40 CFR Subpart T). As

a result, federally funded or approved projects will have to offset any additional growth

in mobile source emissions.

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area by limiting growth from the

mobile sources sector to 2002 levels (for the purposes of “transportation conformity”

determinations - federal transportation conformity regulations of 40 CFR Subpart T). As

a result, federally funded or approved projects will have to offset any additional growth

in mobile source emissions.

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Third, street sweeping is cost-effective in this case because the City is already

conducting some of the sweeping in this rule. Other alternatives, such as alternative

deicers and sand reduction plans, were not considered viable because of concerns

about public safety during winter driving conditions. The potentially lower cost

alternative of one percent fines was not adopted because the City of Steamboat Springs

preferred this control measure. Therefore, it is assumed that the street sweeping

controls and the emission budget are the most cost effective alternative, and the rule

revisions maximize air quality benefits in the most cost effective manner.

Federal Requirements

The adoption of control measures, contingency measures, and emission budgets are

required by federal regulations, and the federal regulations allow the State flexibility in

determining what the measures and budgets should be. These measures and budgets

will be submitted to the EPA as a SIP revision. The rule amendments are not otherwise

more stringent than the requirements of the federal Act.

VIII.E. Redesignating Cañon City/Fremont County PM10 Nonattainment Area to

Attainment and Establishing a New Emissions Budget for the area for 1997

through 2015.

Adopted October 17, 1996

This statement of Basis, Specific Statutory Authority and Purpose complies with the

requirements of the Administrative Procedures Act, C.R.S. 1973, Section 24-4-103(4)

for adopted or modified regulations

eral Act.

VIII.E. Redesignating Cañon City/Fremont County PM10 Nonattainment Area to

Attainment and Establishing a New Emissions Budget for the area for 1997

through 2015.

Adopted October 17, 1996

This statement of Basis, Specific Statutory Authority and Purpose complies with the

requirements of the Administrative Procedures Act, C.R.S. 1973, Section 24-4-103(4)

for adopted or modified regulations. Because the Cañon City/Fremont County

nonattainment area qualifies for redesignation to attainment/maintenance status,

continuation of “nonattainment” status would keep in effect unnecessarily burdensome

requirements for the area's the public and private sectors. Rule changes corresponding

to redesignation are not more stringent than federal requirements.

Basis

The Cañon City/Fremont County PM10 Nonattainment area has never violated the

National Ambient Air Quality Standards for PM10, and has not had an exceedance in

eight years (since May of 1988). Therefore the area is eligible for redesignation to

attainment status under Section 107 of the federal Clean Air Act as amended. Colorado

is formally requesting redesignation and proposing a maintenance plan for the area,

which will become that area's portion of the State Implementation Plan (SIP) upon

USEPA approval. The Ambient Air Standards for the State of Colorado rule must be

revised to reflect the SIP changes.

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federal Clean Air Act as amended. Colorado

is formally requesting redesignation and proposing a maintenance plan for the area,

which will become that area's portion of the State Implementation Plan (SIP) upon

USEPA approval. The Ambient Air Standards for the State of Colorado rule must be

revised to reflect the SIP changes.

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Statutory Authority

General authority for the Ambient Air Standards rule is contained in the Colorado Air

Pollution Prevention and Control Act. §§ 25-7-105 (1) and (2). Specific authority is found

at §§ 25-7-107 (2.5), regarding expeditious redesignation; and 25-7-302, regarding SIP

contents. Commission action in promulgating these revisions is taken pursuant to §§ 25-

7-105(1)(a), regarding establishment of emissions budgets; 25-7-106 (1)(a), regarding

redesignations; 25-7-109(2)(b), regarding the authority to regulate particulate matter.

Federal Requirements

Redesignation to an attainment area is authorized but not strictly required by the federal

act. However, expeditious action to redesignate the area as an attainment area is

required by State statute (25-7-107(2.5)). In order to be meaningful such redesignation

must be submitted to EPA as a SIP revision, and, in fact, § 25-7-107(4) compels that it

be submitted to EPA. Federal law requires the establishment of a motor vehicle

emissions budget in the SIP, either explicitly by identifying such an emissions budget or

implicitly in the maintenance demonstration. The emissions budget required by Federal

law must be consistent with the maintenance of the NAAQS. This rule explicitly

establishes such an emissions budget as a regulation as required by 24-4-103(1), C.

R.S. The motor vehicle emissions budget established in the rule is consistent with

continued maintenance of the NAAQS and therefore complies with, and does not

exceed, this federal requirement.

Purpose

Expeditious action to redesignate to attainment status is taken pursuant to 27-7-

107(2.5), C.R.S

rule explicitly

establishes such an emissions budget as a regulation as required by 24-4-103(1), C.

R.S. The motor vehicle emissions budget established in the rule is consistent with

continued maintenance of the NAAQS and therefore complies with, and does not

exceed, this federal requirement.

Purpose

Expeditious action to redesignate to attainment status is taken pursuant to 27-7-

107(2.5), C.R.S. The proposed revisions to the Ambient Air Standards for the State of

Colorado would implement changes to be made to the State Implementation Plan via

redesignation to attainment for PM10 and adoption and approval of the maintenance

plan for the Cañon City/Fremont County area. The rule revisions would relax certain

requirements for the area. The purpose of an increased mobile source emissions

budget is to provide greater flexibility in making transportation conformity findings, and

to maintain a reasonable margin for accommodation of uncertainty and future growth.

NOTE: Excepting the increase in the area's mobile source emissions budget, the rule

revisions would take effect only upon published USEPA approval of redesignation and of

the maintenance plan. The changes to the Ambient Air Standards would be as follows:

Page 12: Changing the Cañon City/Fremont County classification from

“Moderate” (nonattainment area) to: “Attainment/Maintenance” for the

PM10 NAAQS. This change does not take effect until request/plan is

approved by USEPA.

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ignation and of

the maintenance plan. The changes to the Ambient Air Standards would be as follows:

Page 12: Changing the Cañon City/Fremont County classification from

“Moderate” (nonattainment area) to: “Attainment/Maintenance” for the

PM10 NAAQS. This change does not take effect until request/plan is

approved by USEPA.

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Map page 19: Changing the Cañon City/Fremont County area map from

“nonattainment” to “attainment/maintenance” for PM10. This change does

not take effect until request/plan is approved by USEPA.

Page 23: Motor Vehicle Emission Budget for the area would increase from

5,130 lbs./day to 7,439 lbs./day for 1997 and beyond.

Overall Effect

The overall effect of these rule changes will be to relax the applicable regulations.

These amendments to the rules are not specifically intended to reduce air pollution and,

therefore, the findings in 25-7-110.8(1) are inapplicable.

VIII.F. Longmont Nonattainment Area Redesignation as an attainment area for carbon

monoxide (CO)

Adopted: December 18, 1997

Federal Requirements

42 USC § 7407 (d)(3) provides that the State may request redesignation to attainment

status for areas of the State that qualify for such redesignation based on air quality data,

planning and control considerations. In order for the EPA to approve of such a

redesignation request, § 42 USC §§ 7407(d)(3)(E) and 7505a require the State to

submit a maintenance plan that includes enforceable control measures, will provide for

maintenance of the standard for ten years following the approval of the redesignation

request, and that complies with the requirements of 42 USC § 7410.

EPA policy implementing federal law on maintenance plans gives the State a choice

between two options. Under the first option, the State may develop a simplified

maintenance plan based on a comparison of base-year and future-year emissions

inventories

tenance of the standard for ten years following the approval of the redesignation

request, and that complies with the requirements of 42 USC § 7410.

EPA policy implementing federal law on maintenance plans gives the State a choice

between two options. Under the first option, the State may develop a simplified

maintenance plan based on a comparison of base-year and future-year emissions

inventories. Such a maintenance plan is acceptable if the future-year emissions are less

than the emissions in the base-year. However, this option is available only if the

maintenance plan includes all of the control measures that were included in the

attainment SIP for the area. Under the second option, the State may eliminate control

measures from the maintenance plan, provided that the maintenance plan

demonstrates maintenance of the NAAQS without such control measures. Such a

maintenance demonstration must be supported by dispersion analysis or some other

form of air quality modeling.

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The rule change adopted by the Commission is based on a maintenance plan with a

design value of 5.5 parts per million (ppm). This design value is well below the NAAQS

of 9.0 ppm, and suggests that the State may be able to eliminate some control

measures from the maintenance plan. However, the State has not performed the level

of air quality modeling adequate to justify removal of control measures from the

maintenance plan. Therefore, the State cannot use the second option at this time. The

rule change is supported by a maintenance plan that is based on the first option. Such a

maintenance plan must include all of the control measures that were included in the

attainment SIP in order to comply with federal requirements. Furthermore, the State

may not eliminate the oxygenated fuels program from the Longmont maintenance area

because Longmont is part of the Denver consolidated metropolitan statistical area. 42

USC 7512a(b)(3)

e plan that is based on the first option. Such a

maintenance plan must include all of the control measures that were included in the

attainment SIP in order to comply with federal requirements. Furthermore, the State

may not eliminate the oxygenated fuels program from the Longmont maintenance area

because Longmont is part of the Denver consolidated metropolitan statistical area. 42

USC 7512a(b)(3). Therefore, the rule adopted by the Commission does not differ or

exceed federal requirements.

Statutory Authority

Specific statutory authority for the redesignation of the Longmont area as an attainment

area is provided in § 25-7-107(1).

Findings pursuant to § 25-7-110.8

The rule change adopted by the Commission on October 16, 1997 does not include the

adoption of any additional control measures intended to reduce air pollution. The

Commission's action merely changes the status of the Longmont nonattainment area,

and assigns the safety margin to mobile sources. This rule change provides flexibility for

the community by establishing a Basis for redesignation of the area as an attainment

area, and by allocating the safety margin to the mobile source sector for purposes of

transportation conformity determinations. In the meantime, the Commission has initiated

a process for evaluating whether control measures such as the Automobile Inspection

and Readjustment Program are still necessary to maintain the NAAQS for CO in

Longmont and other communities in Colorado, In this way the rule change provides

greater flexibility in the near term while the Commission continues to evaluate its

options for reducing air pollution and maintaining the NAAQS in the most cost-effective

manner. The Commission has also considered the factors described in § 25-7-109(1)(b)

in adopting these revisions.

VIII.G. Colorado Springs Nonattainment Area Redesignation as an attainment area for

carbon monoxide (CO), and to establish an emissions budget that allocates a

portion of the safety margin to the mobile source sector

Adopted: January 15, 1998

aining the NAAQS in the most cost-effective

manner. The Commission has also considered the factors described in § 25-7-109(1)(b)

in adopting these revisions.

VIII.G. Colorado Springs Nonattainment Area Redesignation as an attainment area for

carbon monoxide (CO), and to establish an emissions budget that allocates a

portion of the safety margin to the mobile source sector

Adopted: January 15, 1998

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Federal Requirements

42 USC §7407(d)(3) provides that the State may request redesignation to attainment

status for areas of the State that qualify for such redesignation based on air quality data,

planning and control considerations. In order for the EPA to approve of such a

redesignation request, § 42 USC §§7407(d)(3)((E) and 7505a require the State to

submit a maintenance plan that includes enforceable control measures, will provide for

maintenance of the standard for ten years following the approval of the redesignation

request, and that complies with the requirements of 42 USC §7410.

EPA policy implementing federal law on maintenance plans generally gives the State a

choice between two options. Under the first option, the State may develop a simplified

maintenance plan based on a comparison of base-year and future-year emissions

inventories. Such a maintenance plan is acceptable if the future-year emissions are less

than the emissions in the base-year. As a general rule, this option is available only if the

maintenance plan includes all of the control measures that were included in the

attainment SIP for the area.

However, pursuant to a memo the EPA sent the Division on October 10, 1997, the State

was able to eliminate the Clean Air Campaign and RIDEFINDERS from the Colorado

Springs carbon monoxide maintenance SIP by supplementing the emission inventory

comparison with additional modeling. EPA concurred that these two SIP elements

(RIDEFINDERS and the Clean Air Campaign) may be deleted in accordance with its

maintenance SIP policy

emo the EPA sent the Division on October 10, 1997, the State

was able to eliminate the Clean Air Campaign and RIDEFINDERS from the Colorado

Springs carbon monoxide maintenance SIP by supplementing the emission inventory

comparison with additional modeling. EPA concurred that these two SIP elements

(RIDEFINDERS and the Clean Air Campaign) may be deleted in accordance with its

maintenance SIP policy. Under the second option, the State may eliminate control

measures from the maintenance plan, provided that the maintenance plan

demonstrates maintenance of the NAAQS without such control measures. Such a

maintenance demonstration must be supported by adequate air quality modeling or

analysis.

There is reason to believe that the state may be able to eliminate either the oxygenated

fuels program or the motor vehicle inspection and maintenance program, and still

demonstrate maintenance of the NAAQS for carbon monoxide for the Colorado Springs

area. However, the State has not performed the air quality modeling necessary to justify

removal such control measures. Therefore, the State cannot use the second option at

this time. The rule change is supported by a maintenance plan that is based on the first

option. Such a maintenance plan must include all of the control measures that were

included in the attainment SIP in order to comply with federal requirements. EPA has

concurred with the Division's and the Pikes Peak Area Council of Governments'

inventory and supplemental modeling was adequate to support the removal of the

RIDEFINDERS and Clean Air Campaigns from the Colorado Springs carbon monoxide

maintenance SIP because these control strategies will not impact maintenance of the

NAAQS.

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concurred with the Division's and the Pikes Peak Area Council of Governments'

inventory and supplemental modeling was adequate to support the removal of the

RIDEFINDERS and Clean Air Campaigns from the Colorado Springs carbon monoxide

maintenance SIP because these control strategies will not impact maintenance of the

NAAQS.

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Statutory Authority

Specific statutory authority for the redesignation of the Colorado Springs area as an

attainment area is provided in §25-7-107(1).

Findings pursuant to §25-7-110.8

The rule change adopted by the Commission on January 15, 1998 does not include the

adoption of any additional control measures intended to reduce air pollution. The

Commission's action merely changes the status of the Colorado Springs nonattainment

area, and allocates a portion of the safety margin in the year 2010 to the mobile source

sector.

The redesignation of the area was based on reasonably available, validated, reviewed

and sound scientific methodologies, which are described in the maintenance plan

narrative and the Final Emission Inventories for the Colorado Springs, Colorado,

Carbon Monoxide Nonattainment Area Redesignation Plan. Such documents have been

available for public review in draft form for several months, and have been revised in

response to comments and review. Final documents were available thirty days prior to

the hearing.

The redesignation of the Colorado Springs area as an attainment area is the most cost-

effective alternative. Such redesignation provides the regulated community with

flexibility, yet maintains the National Ambient Air Quality Standard (NAAQS) for carbon

monoxide.

Contested issues

The maintenance plan associated with the rule change does not include two control

measures (RIDEFINDERS and the Clean Air Campaign) that were previously included

in the State Implementation Plan (SIP). Several parties to the hearing objected to the

removal of these measures from the SIP

exibility, yet maintains the National Ambient Air Quality Standard (NAAQS) for carbon

monoxide.

Contested issues

The maintenance plan associated with the rule change does not include two control

measures (RIDEFINDERS and the Clean Air Campaign) that were previously included

in the State Implementation Plan (SIP). Several parties to the hearing objected to the

removal of these measures from the SIP. The Commission voted to remove the

RIDEFINDERS and the Clean Air Campaign from the mandatory sections of the SIP in

deference to the request of the Pikes Peak Area Council of Governments, the lead air

quality-planning agency for the Colorado Springs area, pursuant to CRS §25-7-

105(1)(a)(II). These measures are not necessary to maintain the NAAQS and are not

otherwise federally required. Therefore, pursuant to §25-7-105.1, these measures

should not be included in the maintenance plan. Furthermore, these control measures

were not implemented by rule. Accordingly no rule change is necessary to remove such

measures from the SIP.

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As indicated above, the Commission chose to redesignate the area by comparing the

base-year and future-year inventories, and the Division did not perform air quality

modeling adequate to justify the removal of the oxygenated fuels program from the SIP.

Several parties urged the removal of the oxygenated fuels program from the plan.

However, such revision of the plan would have delayed the redesignation of the area

pending further air quality analysis, and would have required substantial revisions to the

maintenance plan. The Colorado Springs area would remain a nonattainment area in

the meantime.

The Commission has initiated a process for evaluating whether control measures such

as the oxygenated fuels program and the Automobile Inspection and Readjustment (I/M)

Program are still necessary to maintain the NAAQS for CO in the Colorado Springs area

and other communities in Colorado

revisions to the

maintenance plan. The Colorado Springs area would remain a nonattainment area in

the meantime.

The Commission has initiated a process for evaluating whether control measures such

as the oxygenated fuels program and the Automobile Inspection and Readjustment (I/M)

Program are still necessary to maintain the NAAQS for CO in the Colorado Springs area

and other communities in Colorado. For these reasons, the Commission has decided to

approve of the maintenance plan and to redesignate the area, but also agrees that the

evaluation of the need for the control measures should be expedited. PPACG has

proposed that the Air Pollution Control Division expedite analyses of whether

oxygenated fuels program is necessary to demonstrate maintenance of the carbon

monoxide NAAQS in the Colorado Springs area. This evaluation is consistent with the

Division's ongoing consideration of future carbon monoxide control strategies for

Colorado's Front Range, and PPACG suggests that an expedited Colorado Springs

evaluation could provide valuable information and experience for other areas eligible for

redesignation to attainment status. This evaluation shall include both 1990 and 1993

base-years.

The APCD will report its progress to the PPACG and the Air Quality Control Commission

in writing in March and June 1998, and will submit the results of said analyses to

PPACG and other interested parties.

The PPACG has agreed to review the information, and will make an initial determination

regarding whether oxygenated fuels are necessary to maintain the federal carbon

monoxide NAAQS within 90 days of receipt of the technical analysis. If the oxygenated

fuels program is not necessary to maintain the federal CO standards, PPACG has

agreed to petition the Commission for revision of Regulation 13 and the Colorado

Springs maintenance plan to reduce the oxygen content requirement or recategorize

that program as a “contingency measure,” as appropriate in light of the analyses

NAAQS within 90 days of receipt of the technical analysis. If the oxygenated

fuels program is not necessary to maintain the federal CO standards, PPACG has

agreed to petition the Commission for revision of Regulation 13 and the Colorado

Springs maintenance plan to reduce the oxygen content requirement or recategorize

that program as a “contingency measure,” as appropriate in light of the analyses.

Similarly, the Division and other interested persons may petition for revisions to the I/M

Program, or removal of such program from the State Implementation Plan.

Based on this schedule, the Technical Secretary to the Commission has agreed to

amend the Commission's long-term schedule and tentatively to set a hearing date as

requested by the PPACG as early as practical.

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Several parties also objected to the process used by Pikes Peak Area Council of

Governments (PPACG) to develop the maintenance plan. The procedure used by the

PPACG to develop the maintenance plan complied with the minimum requirements of

the Intergovernmental Coordination and Public Involvement process (“the ICPI”)

contained in the 1982 Colorado Springs Element of the Carbon Monoxide State

Implementation Plan (Including the 1993 and 1994 revisions) (“the Colorado Springs

attainment SIP”).

The primary complaint lodged by the parties is that the PPACG did not adequately

consult with the Air Quality Technical Committee (AQTC). However, it appears that the

staff of the PPACG consulted with the AQTC, and did so most recently on October 22,

1997 and November 18, 1997. In addition, members of the AQTC presented their

complaints to the PPACG in September 1997. Pursuant to the Colorado Springs

Attainment SIP, the PPACG is the lead agency for air quality planning and the AQTC is

merely an advisory committee. The PPACG is not required to heed the advice of the

AQTC. The consultation with AQTC complied with the minimum requirements of the

ICPI

and November 18, 1997. In addition, members of the AQTC presented their

complaints to the PPACG in September 1997. Pursuant to the Colorado Springs

Attainment SIP, the PPACG is the lead agency for air quality planning and the AQTC is

merely an advisory committee. The PPACG is not required to heed the advice of the

AQTC. The consultation with AQTC complied with the minimum requirements of the

ICPI.

The parties also complain that the maintenance plan had to be approved by the Urban

Area Planning Council (UAPC), rather than the PPACG's Board of Directors. However,

nothing in the Colorado Springs Attainment SIP implies that the PPACG Board of

Directors does not have the authority to develop the maintenance plan. The Colorado

Springs Attainment SIP identifies the PPACG as the lead air quality-planning agency,

and identifies the UAPC as the Metropolitan Planning Agency for transportation matters

, unless objected to by the PPACG. Colorado Springs Attainment SIP, Appendix A. The

UAPC is advisory to the PPACG on all other matters, including air quality planning. Id.

Furthermore, according to Ken Prather of PPACG, the UAPC recommended approval of

the maintenance plan and redesignation request.

The agreements and schedules set out in this Statement of Basis, Specific Statutory

Authority, and Purpose shall not be included in the SIP, and this statement of basis,

specific statutory authority and purpose shall not be construed to create enforceable

requirements.

VIII.H. Total Suspended Particulate Matter Revocation

Adopted: September 17, 1998

The Commission revoked the Colorado ambient air quality standard for Total

Suspended Particulate matter to conform Colorado's standards to the current National

Ambient Air Quality Standards for Particulate Matter adopted by the U.S. Environmental

Protection Agency.

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d Particulate Matter Revocation

Adopted: September 17, 1998

The Commission revoked the Colorado ambient air quality standard for Total

Suspended Particulate matter to conform Colorado's standards to the current National

Ambient Air Quality Standards for Particulate Matter adopted by the U.S. Environmental

Protection Agency.

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Federal Requirements

The State ambient standard for TSP is based on the National Ambient Air Quality

Standard (NAAQS) for TSP that the Environmental Protection Agency (“EPA” ) repealed

in 1987 in favor of the NAAQS for particulate matter less than ten microns in diameter

(PM10). The NAAQS for PM10 is less stringent than the State ambient standard for

TSP. The repeal of the TSP standard will ensure that Colorado's ambient air quality

standards for particulate matter meet, but do not exceed, federal requirements.

The federal government no longer has an ambient air quality standard for particulate

matter as TSP. Standards for the PM10 and PM2.5 size ranges have been adopted

instead. EPA believes that PM10 and PM2.5, the smaller diameter particles, can travel

deeper into the lungs than TSP, and has found that the NAAQS for PM10 and PM2.5

adequately protect public health. The federal Clean Air Act requires Colorado to adopt

the new federal standards, which regulate particulate matter as PM10 and PM2.5.

Retention of the state TSP standard would regulate particulate matter in all three-size

ranges. The regulation of particulate matter in all three-size ranges is not necessary,

and is not cost-effective.

The repeal of the ambient air quality standard for TSP shall be submitted to EPA as a

SIP revision.

Statutory Authority

§ 25-7 108, C.R.S., authorizes the Commission to revoke the TSP ambient air quality

standard

e state TSP standard would regulate particulate matter in all three-size

ranges. The regulation of particulate matter in all three-size ranges is not necessary,

and is not cost-effective.

The repeal of the ambient air quality standard for TSP shall be submitted to EPA as a

SIP revision.

Statutory Authority

§ 25-7 108, C.R.S., authorizes the Commission to revoke the TSP ambient air quality

standard. This section allows the Commission “to adopt, promulgate, amend, and

modify such standards for the quality of ambient air as may be appropriate or

necessary.”

Findings Pursuant to Colorado Revised Statutes 25-7-110.8

This rule change does not include the adoption of any additional control measures

intended to reduce air pollution. The Commission's action merely revokes an ambient

air quality standard that is not federally required.

VIII.I. Denver metropolitan nonattainment area redesignation as an attainment area for

carbon monoxide

Adopted: January 10, 2000

The amendments to the “Ambient Air Quality Standards for the State of Colorado”

Regulation adopted by the Commission change the air quality classification of the

Denver area for carbon monoxide. The purpose of this rule change is to implement the

direction in § 25-7-107 (2.5), C.R.S. to take expeditious action to redesignate the area

as attainment for carbon monoxide (CO).

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The amendments also revise the mobile source emissions budget used to determine

whether transportation plans and projects conform to the State Implementation Plan.

Federal Requirements

42 USC Section 7407(d)(3) provides that the State may request redesignation to

attainment status for areas of the State that qualify for such redesignation based on air

quality data, and planning and control considerations

ndments also revise the mobile source emissions budget used to determine

whether transportation plans and projects conform to the State Implementation Plan.

Federal Requirements

42 USC Section 7407(d)(3) provides that the State may request redesignation to

attainment status for areas of the State that qualify for such redesignation based on air

quality data, and planning and control considerations. In order for the EPA to approve of

such a redesignation request, 42 USC Sections 7407(d)(3)(E) and 7505a require the

State to submit a maintenance plan that will provide for maintenance of the standard for

ten years following the approval of the redesignation request. The federal requirements

for preparation, adoption and submittal of implementation plans, including the

maintenance plan, are set out at 40 CFR, Part 51.

The maintenance plan adopted by the Commission includes an oxygenated fuels

program and an Automobile Inspection and Readjustment Program as necessary to

maintain the National Ambient Air Quality Standards (NAAQS) for carbon monoxide

through the year 2013. The year 2013 is approximately ten years following the

anticipated date of EPA approval of the maintenance plan. The federal requirements for

emissions budgets are set out at 42 USC Section 7506(c) and 40 CFR 93.124. The

emissions budget establishes a test for determining whether transportation plans or

projects may cause or contribute to a violation of the NAAQS. The emissions budget

contained in the maintenance plan is based on the mobile source emission inventories

supporting the maintenance demonstration. The maintenance plan does not include any

provisions that are not required by provisions of the federal act or that are otherwise

more stringent than requirements of the federal act.

Statutory Authority

Specific statutory authority for the redesignation of the Denver area as an attainment

area is provided in § 25-7-107, C.R.S. (1999)

e emission inventories

supporting the maintenance demonstration. The maintenance plan does not include any

provisions that are not required by provisions of the federal act or that are otherwise

more stringent than requirements of the federal act.

Statutory Authority

Specific statutory authority for the redesignation of the Denver area as an attainment

area is provided in § 25-7-107, C.R.S. (1999).

Findings pursuant to § 25-7-110.8

The mobile source emissions budget is the only control included in the amendments

that will operate to reduce air pollution. The emissions budget establishes a cap on

mobile source emissions and is administered though the transportation conformity

regulations. Air Quality Control Commission Regulation Number 10, Part B; 40 CFR

Part 93. The December 16, 1999 rule amendments reduced the mobile source

emissions budget from 825 tons per day to 800 tons per day.

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The revisions are based on the computer model currently approved by the EPA. The

computer model used to develop the revised rule overstates the air quality benefits of

some of the control programs in the SIP. The EPA is currently updating and improving

the computer model but the revised computer model has not been approved by EPA

and may not be used for federal regulatory purposes. In spite of the problems with the

computer model used to develop this regulation, the regulation is based on the most

reasonably available, validated, reviewed and sound scientific methodologies currently

available under federal law. All methodologies and information made available by

interested parties have been considered.

The alternative to the redesignation of the Denver area to an attainment area is to for

the Denver area to remain a nonattainment area for carbon monoxide. Redesignation to

attainment is the more cost-effective alternative

, reviewed and sound scientific methodologies currently

available under federal law. All methodologies and information made available by

interested parties have been considered.

The alternative to the redesignation of the Denver area to an attainment area is to for

the Denver area to remain a nonattainment area for carbon monoxide. Redesignation to

attainment is the more cost-effective alternative. Redesignation provides the regulated

community with more flexibility and achieves the reductions in air pollution necessary to

maintain the NAAQS. There is no viable alternative to limiting mobile source emissions

to 800 tons per day in the year 2013. Mobile source emissions can be effectively

controlled using the measures described in the maintenance plan to keep mobile source

emissions below the emissions budget. Thus, the revision to the ambient air quality

standard will maximize the air quality benefits of the Commission's regulations in the

most cost-effective manner.

VIII.J. Colorado Springs

Adopted: February 17, 2000

The amendments to the “Ambient Air Quality Standards for the State of Colorado”

Regulation adopted by the Commission revise the mobile source emissions budgets for

the Colorado Springs area. The emissions budget is to determine whether

transportation plans and projects conform to the State Implementation Plan.

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Federal Requirements

The federal requirements for emissions budgets are set out at 42 USC 7506(c) and 40

CFR 93.124. The emissions budget establishes a test for determining whether

transportation plans or projects may cause or contribute to a violation of the national

ambient air quality standard (NAAQS). The emissions budget for Colorado Springs is

based on the mobile source inventory for the year 1990. The previous emissions

budget, which was adopted in January 1998, was based on the mobile source inventory

for the year 1993

udget establishes a test for determining whether

transportation plans or projects may cause or contribute to a violation of the national

ambient air quality standard (NAAQS). The emissions budget for Colorado Springs is

based on the mobile source inventory for the year 1990. The previous emissions

budget, which was adopted in January 1998, was based on the mobile source inventory

for the year 1993. Some parties to the January 1998 hearing urged the Commission to

adopt an emissions budget based on 1990, rather than 1993, mobile source emissions.

The Commission did not have sufficient data or evidence at the January 1998 hearing to

establish an emissions budget based on the 1990 base year. Therefore, the

Commission adopted an emissions budget based on the 1993 base year and directed

the Division to evaluate the request to establish an emissions budget based on 1990

mobile source emissions. Colorado Springs was in attainment of the national standard

in both 1990 and 1993 but mobile source emissions were significantly higher in 1990

than in 1993. As authorized by federal regulations, this revision establishes a higher

emissions budget for mobile sources based on the 1990 mobile source inventory. The

regulatory revisions do not include any provisions that are not required by provisions of

the federal act or that are otherwise more stringent than requirements of the federal act.

Statutory Authority

The authority to establish emissions budgets is included in the general authority to

adopt a State Implementation Plan set out in § 25-7-105(1), C.R.S. (1999).

Findings pursuant to § 25-7-110.8

The emissions budget establishes a cap on mobile source emissions and will be

administered though the transportation conformity regulations. Air Quality Control

Commission Regulation Number 10, Part B; 40 CFR Part 93. The change increases the

emissions budget, and thus increases the allowable emissions from mobile sources.

The carbon monoxide emissions budget is based on the computer model currently

approved by the EPA

stablishes a cap on mobile source emissions and will be

administered though the transportation conformity regulations. Air Quality Control

Commission Regulation Number 10, Part B; 40 CFR Part 93. The change increases the

emissions budget, and thus increases the allowable emissions from mobile sources.

The carbon monoxide emissions budget is based on the computer model currently

approved by the EPA. The computer model used to develop the revised rule overstates

the air quality benefits of some of the control programs in the SIP. The EPA is currently

updating and improving the computer model but the revised computer model has not

been approved by EPA and may not be used for federal regulatory purposes, In spite of

the problems with the computer model used to develop this regulation, the regulation is

based on the most reasonably available, validated, reviewed and sound scientific

methodologies currently available under federal law. All methodologies and information

made available by interested parties have been considered. The revisions to the

ambient air quality standard will maximize the air quality benefits of the Commission's

regulations in the most cost-effective manner.

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VIII.K. Denver, Ozone Maintenance Plan

Adopted: January 11, 2001

The amendments to the Ambient Air Quality Standards for the State of Colorado revise

the mobile source emissions budgets for ozone precursors in the Denver metropolitan

area. The emissions budgets are used to determine whether transportation plans and

projects conform to the State Implementation Plan.

Federal Requirements

The federal requirements for emissions budgets are set out at 42 USC 7506(c) and 40

CFR 93.124. The emissions budget establishes a test for determining whether

transportation plans or projects may cause or contribute to a violation of the national

ambient air quality standard (NAAQS)

determine whether transportation plans and

projects conform to the State Implementation Plan.

Federal Requirements

The federal requirements for emissions budgets are set out at 42 USC 7506(c) and 40

CFR 93.124. The emissions budget establishes a test for determining whether

transportation plans or projects may cause or contribute to a violation of the national

ambient air quality standard (NAAQS).

The maintenance plan must include emission budgets for ozone precursors, but the

federal rules allow the State some discretion in setting the emissions budgets. The

State may set an emission budget equal to the projected emissions from motor vehicles

in the last year of the maintenance plan. Alternatively, the State may establish a higher

emissions budget for mobile sources if the area could tolerate such higher emissions

without exceeding the relevant NAAQS. 40 CFR 93.124. The Denver area can tolerate

additional mobile source emissions of ozone precursors. The emissions budgets

established in this rulemaking make this entire amount of additional emissions available

to DRCOG and CDOT for conformity purposes. The rule revision is not more stringent

than requirements of the federal act.

Statutory Authority

The authority to establish emissions budgets is included in the general authority to

adopt a State Implementation Plan set out in Section 25-7-105(1), C.R.S. (1999).

Findings pursuant to § 25-7-110.8

The emissions budgets are based on EPA-approved models and assumptions for

estimating emissions from mobile sources. The Commission believes the EPA-approved

model is inaccurate, but federal rules require the State to use such model to

demonstrate the adequacy of the maintenance plan. Thus, the rule revision is based on

the only scientific methodology authorized for use by federal law. All methodologies and

information made available by interested parties have been considered

ating emissions from mobile sources. The Commission believes the EPA-approved

model is inaccurate, but federal rules require the State to use such model to

demonstrate the adequacy of the maintenance plan. Thus, the rule revision is based on

the only scientific methodology authorized for use by federal law. All methodologies and

information made available by interested parties have been considered.

The revisions to the ambient air quality standard will maximize the air quality benefits of

the Commission's regulations in the most cost-effective manner.

VIII.L. Pagosa Springs and Telluride PM10

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Adopted: March 16, 2001

The amendments to the “Ambient Air Quality Standards” for the State of Colorado

Regulation adopted by the Commission change the air quality classifications of the

Pagosa Springs area and the Telluride area for particulate matter. The purpose of this

rule change is to implement the direction in § 25-7-107 (2.5), C.R.S. (1999) to take

expeditious action to redesignate the areas as attainment for particulate matter less

than ten microns in diameter (PM10). The Commission also adopted simultaneous

revisions to the “State Implementation Plan Specific Regulations for Nonattainment -

Attainment/Maintenance Areas” to repeal obsolete control measures, contingency

measures, and reporting requirements.

The amendments to the “Ambient Air Quality Standards” for the State of Colorado also

revise the mobile source emissions budgets for the Pagosa Springs and Telluride areas.

The emissions budgets are used to determine whether transportation plans and projects

conform to the State Implementation Plan.

Federal Requirements

42 USC 7407(d)(3) provides that the State may request redesignation to attainment

status for areas of the State that qualify for such redesignation based on air quality data,

and planning and control considerations

Pagosa Springs and Telluride areas.

The emissions budgets are used to determine whether transportation plans and projects

conform to the State Implementation Plan.

Federal Requirements

42 USC 7407(d)(3) provides that the State may request redesignation to attainment

status for areas of the State that qualify for such redesignation based on air quality data,

and planning and control considerations. In order for the EPA to approve such a

redesignation request, 42 USC Sections 7407(d)(3)((E) and 7505a require the State to

submit a maintenance plan that will provide for maintenance of the standard for ten

years following the approval of the redesignation request. The federal requirements for

preparation, adoption and submittal of implementation plans, including the maintenance

plan, are set out at 40 CFR, Part 51. The maintenance plans adopted by the

Commission will maintain the national standard for PM10 in Pagosa Springs and

Telluride for the requisite ten-year period.

The federal requirements for emissions budgets are set out at 42 USC 7506(c) and 40

CFR 93.124. The emissions budget establishes a test for determining whether

transportation plans or projects may cause or contribute to a violation of the national

ambient air quality standard (NAAQS). The emissions budgets for Telluride and Pagosa

Springs are based on the roll-forward analyses that support the maintenance

demonstrations.

The regulatory revisions do not include any provisions that are not required by

provisions of the federal act or that are otherwise more stringent than requirements of

the federal act.

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. The emissions budgets for Telluride and Pagosa

Springs are based on the roll-forward analyses that support the maintenance

demonstrations.

The regulatory revisions do not include any provisions that are not required by

provisions of the federal act or that are otherwise more stringent than requirements of

the federal act.

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Statutory Authority

Specific statutory authority to redesignate areas to attainment is provided in § 25-7-107,

C.R.S. (1999). The authority to establish emissions budgets is included in the general

authority to adopt a State Implementation Plan set out in § 25-7-105(1), C.R.S. (1999).

Findings pursuant to § 25-7-110.8

The mobile source emissions budgets are the only control measures included in the

amendments that will operate to reduce air pollution. The emissions budgets establish

caps on mobile source emissions and are administered though the transportation

conformity regulations. Air Quality Control Commission Regulation Number 10, Part B;

40 CFR Part 93. For Pagosa Springs, the change increases the emissions budget, and

thus increases the allowable emissions from mobile sources. The rule revisions

decrease the allowable mobile source emissions of PM10 in Telluride.

The emissions budgets for PM10 for Pagosa Springs and Telluride are also based on

EPA-approved models and assumptions for estimating PM10 emissions from mobile

sources. The Commission believes the EPA-approved model is inaccurate, but federal

rules require the State to use such model to demonstrate the adequacy of the

maintenance plan. In spite of the problems with the computer model used to develop

the regulation, the regulation is based on the most reasonably available, validated,

reviewed and sound scientific methodologies currently available under federal law. All

methodologies and information made available by interested parties have been

considered

tate to use such model to demonstrate the adequacy of the

maintenance plan. In spite of the problems with the computer model used to develop

the regulation, the regulation is based on the most reasonably available, validated,

reviewed and sound scientific methodologies currently available under federal law. All

methodologies and information made available by interested parties have been

considered.

The alternative to the redesignation of the Pagosa Springs and Telluride areas to

attainment is for them to remain PM10 nonattainment areas. Redesignation to

attainment is the more cost-effective alternative. Redesignation provides the regulated

community with more flexibility and achieves the reductions in air pollution necessary to

maintain the NAAQS. The revisions to the ambient air quality standard will maximize the

air quality benefits of the Commission's regulations in the most cost-effective manner.

VIII.M. Denver Metropolitan Area, Redesignation to Attainment for PM10

Adopted: April 19, 2001

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The amendments to the “Ambient Air Quality Standards for the State of Colorado”

Regulation adopted by the Commission change the air quality classification of the

Denver metropolitan area for particulate matter. The purpose of this rule change is to

implement the direction in § 25-7-107 (2.5), C.R.S. (1999) to take expeditious action to

redesignate the area as attainment for particulate matter less than ten microns in

diameter (PM10). In conjunction with this redesignation, the Commission revised

Regulation Number 16, “Street Sanding Emissions” to implement the control measures

necessary to maintain the national standard for PM10 for at least ten years.

The change in the classification of the Denver area affects the regulatory requirements

applicable to stationary sources

iculate matter less than ten microns in

diameter (PM10). In conjunction with this redesignation, the Commission revised

Regulation Number 16, “Street Sanding Emissions” to implement the control measures

necessary to maintain the national standard for PM10 for at least ten years.

The change in the classification of the Denver area affects the regulatory requirements

applicable to stationary sources. For most types of sources, the threshold for

determining whether or not a source is a “major stationary source” for PM, NOx or S02

increases from 100 tons-per-year to 250 tons-per-year. Similarly, the requirements for

new major stationary sources to use the lowest achievable emissions rate, and to obtain

offsets, are relaxed.

The rule change adopted by the Commission, however, maintains existing requirements

in Regulation Number 3 for minor sources in the Denver area to use reasonably

available control technology. The Commission intends, however, to review this

requirement when it reviews Regulation Number 3. The amendments to the “Ambient

Air Quality Standards for the State of Colorado” also revise the PM10 mobile source

emissions budget for the Denver metropolitan area. The emissions budget is used to

determine whether transportation plans and projects conform to the State

Implementation Plan.

Federal Requirements

42 USC 7407(d)(3) provides that the State may request redesignation to attainment

status for areas of the State that qualify for such redesignation based on air quality data,

and planning and control considerations. In order for the EPA to approve such a

redesignation request, 42 USC Sections 7407(d)(3)((E) and 7505a require the State to

submit a maintenance plan that will provide for maintenance of the standard for ten

years following the approval of the redesignation request. The federal requirements for

preparation, adoption and submittal of implementation plans, including the maintenance

plan, are set out at 40 CFR, Part 51

A to approve such a

redesignation request, 42 USC Sections 7407(d)(3)((E) and 7505a require the State to

submit a maintenance plan that will provide for maintenance of the standard for ten

years following the approval of the redesignation request. The federal requirements for

preparation, adoption and submittal of implementation plans, including the maintenance

plan, are set out at 40 CFR, Part 51. The maintenance plans adopted by the

Commission will maintain the national standard for PM10 for the requisite ten-year

period.

The federal requirements for emissions budgets are set out at 42 USC 7506(c) and 40

CFR 93.124. The emissions budget establishes a test for determining whether

transportation plans or projects may cause or contribute to a violation of the national

ambient air quality standard (NAAQS). The emissions budget is based on the analysis

that supports the maintenance demonstration.

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The regulatory revisions do not include any provisions that are not required by

provisions of the federal act or that are otherwise more stringent than requirements of

the federal act.

Statutory Authority

Specific statutory authority to redesignate areas to attainment is provided in § 25-7-107,

C.R.S. (1999). The authority to establish emissions budgets is included in the general

authority to adopt a State Implementation Plan set out in § 25-7-105(1), C.R.S. (1999).

Findings pursuant to § 25-7-110.8

The mobile source emissions budgets are the only control measures included in the

amendments to the Ambient Air Quality Standards rule that will operate to reduce air

pollution. The reference to Regulation Number 3 added to the Ambient Air Quality

Standards merely maintains the status quo; it does not establish any new requirement.

The emissions budgets establish caps on mobile source emissions and are

administered though the transportation conformity regulations. Air Quality Control

Commission Regulation Number 10, Part B; 40 CFR Part 93

operate to reduce air

pollution. The reference to Regulation Number 3 added to the Ambient Air Quality

Standards merely maintains the status quo; it does not establish any new requirement.

The emissions budgets establish caps on mobile source emissions and are

administered though the transportation conformity regulations. Air Quality Control

Commission Regulation Number 10, Part B; 40 CFR Part 93. By capping mobile source

emissions at a prescribed limit, the emission budget could result in a demonstrable

reduction in air pollution.

The emissions budgets are based on EPA-approved models and assumptions for

estimating PM10 emissions from mobile sources. The Commission believes the EPA-

approved models are inaccurate, but federal rules require the State to use such models

to demonstrate the adequacy of the maintenance plan. Thus, the emissions budgets are

based on the only methodologies authorized for use by federal law. All methodologies

and information made available by interested parties have been considered.

The alternative to redesignation is for the Denver area to remain a PM10 nonattainment

area. Redesignation to attainment is the more cost-effective alternative. Redesignation

provides the regulated community with more flexibility and achieves the reductions in air

pollution necessary to maintain the NAAQS. The revisions to the ambient air quality

standard will maximize the air quality benefits of the Commission's regulations in the

most cost-effective manner.

VIII.N. Lamar and Steamboat Springs, Redesignation to Attainment for PM10

Adopted: November 15, 2001

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ves the reductions in air

pollution necessary to maintain the NAAQS. The revisions to the ambient air quality

standard will maximize the air quality benefits of the Commission's regulations in the

most cost-effective manner.

VIII.N. Lamar and Steamboat Springs, Redesignation to Attainment for PM10

Adopted: November 15, 2001

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The amendments to the “Ambient Air Quality Standards for the State of Colorado”

Regulation adopted by the Commission change the air quality classifications of the

Steamboat Springs and Lamar areas to attainment/maintenance for particulate matter,

and revise the mobile source emissions budgets for these areas. The Commission

adopted simultaneous revisions to the “State Implementation Plan-Specific Regulation

for Nonattainment Areas” to repeal obsolete contingency measures.

Federal Requirements

The relevant federal requirements are described in detail in the statement of basis,

specific statutory authority and purpose for Pagosa Springs and Telluride published in

Section VIII.L. of the ambient air quality standards regulation. Nothing in this rule

change exceeds the minimum requirements of the federal act.

Statutory Authority

Specific statutory authority to redesignate areas to attainment is provided in § 25-7-107,

C.R.S. (1999). The authority to establish emissions budgets is included in the general

authority to adopt a State Implementation Plan set out in § 25-7-105(1), C.R.S. (1999).

Findings pursuant to § 25-7-110.8

The mobile source emission budget is the only control measures included in the

amendments that will operate to reduce air pollution. The emissions budget is based on

EPA-approved models and assumptions for estimating PM10 emissions from mobile

sources. The Commission believes the EPA-approved model is inaccurate, but federal

rules require the State to use such model to demonstrate the adequacy of the

maintenance plan

ission budget is the only control measures included in the

amendments that will operate to reduce air pollution. The emissions budget is based on

EPA-approved models and assumptions for estimating PM10 emissions from mobile

sources. The Commission believes the EPA-approved model is inaccurate, but federal

rules require the State to use such model to demonstrate the adequacy of the

maintenance plan. All methodologies and information made available by interested

parties have been considered.

The alternative to the redesignation of the areas to attainment is for these areas to

remain PM10 nonattainment areas. Redesignation to attainment is the more cost-

effective alternative. Redesignation provides the regulated community with more

flexibility and achieves the reductions in air pollution necessary to maintain the NAAQS.

The revisions to the ambient air quality standard will maximize the air quality benefits of

the Commission's regulations in the most cost-effective manner.

VIII.O. Fort Collins

Adopted: July 18, 2002

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The amendments to the “Ambient Air Quality Standards for the State of Colorado”

Regulation adopted by the Commission change the air quality classification of the Fort

Collins area to attainment/maintenance for carbon monoxide and establish a mobile

source emissions budget for the area. The Commission adopted simultaneous revisions

to Regulation Number 11, Regulation Number 13 and the “State Implementation Plan-

Specific Regulation for Nonattainment Areas.”

The Commission also repealed Section V.B, “Requirement Regarding Enforceability.”

Section V.B established criteria for emission reduction credit in transportation conformity

determinations. Federal regulations already establish such criteria. 40 CFR 93.122.

Although Section V.B

ulation Number 11, Regulation Number 13 and the “State Implementation Plan-

Specific Regulation for Nonattainment Areas.”

The Commission also repealed Section V.B, “Requirement Regarding Enforceability.”

Section V.B established criteria for emission reduction credit in transportation conformity

determinations. Federal regulations already establish such criteria. 40 CFR 93.122.

Although Section V.B. was similar to the federal criteria set out at 40 CFR 93.122,

Section V.B did not expressly authorize the option of taking credit for a control measure

based on a SIP commitment to implement such a program. Thus, Section V.B appeared

to deny transportation agencies an option that is available under the federal rules. The

maintenance plan adopted by the Commission in conjunction with these changes to the

Ambient Air Quality Standards regulations includes a commitment to implement an

automobile testing program in the year 2026. Under the federal rules, such a

commitment will allow the Colorado Department of Transportation to take emission

reduction credit for the inspection program when it makes transportation conformity

determinations that extend beyond 2026. The Commission repealed Section V.B so that

the rules for taking credit during transportation conformity determinations are identical to

the federal rules on the subject. Elsewhere, in Regulation Number 10, Part B, the

Commission has already passed a state regulation requiring transportation agencies to

comply with the federal rules when performing transportation conformity determinations.

Therefore, Section V.B was confusing and unnecessary, and may have exceeded the

minimum federal requirements. Finally, the Commission made several minor

housekeeping changes and repealed obsolete provisions

ber 10, Part B, the

Commission has already passed a state regulation requiring transportation agencies to

comply with the federal rules when performing transportation conformity determinations.

Therefore, Section V.B was confusing and unnecessary, and may have exceeded the

minimum federal requirements. Finally, the Commission made several minor

housekeeping changes and repealed obsolete provisions.

Federal Requirements

The federal requirements relevant to the redesignation and the emission budget are

described in detail in the statement of basis, specific statutory authority and purpose for

Pagosa Springs and Telluride published in Section VIII.L of the ambient air quality

standards regulation. The federal regulation establishing criteria for taking credit in

transportation conformity determinations is set out at 40 CFR 93.122. Nothing in this

rule change exceeds the minimum requirements of the federal act.

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Statutory Authority

Specific statutory authority to redesignate areas to attainment is provided in § 25-7-107,

C.R.S. (1999). The authority to establish emissions budgets and to establish criteria for

transportation conformity determinations is included in the general authority to adopt a

State Implementation Plan set out in § 25-7-105(1), C.R.S. (1999).

Findings pursuant to § 25-7-110.8

The mobile source emission budget is the only control measures included in the

amendments that will operate to reduce air pollution. The emissions budget is based on

EPA's recently released MOBILE6. Federal rules require the State to use a model

approved by EPA. The Commission believes that the MOBILE6 model is superior to the

MOBILE5 model that was used to develop earlier SIPs. All methodologies and

information’s made available by interested parties have been considered.

The alternative to the redesignation of the areas to attainment is for the Fort Collins

area to remain a nonattainment area for carbon monoxide

the State to use a model

approved by EPA. The Commission believes that the MOBILE6 model is superior to the

MOBILE5 model that was used to develop earlier SIPs. All methodologies and

information’s made available by interested parties have been considered.

The alternative to the redesignation of the areas to attainment is for the Fort Collins

area to remain a nonattainment area for carbon monoxide. Redesignation to attainment

is the more cost-effective alternative. Redesignation provides the regulated community

with more flexibility and maintains the reductions in air pollution necessary to maintain

the NAAQS. In particular, it allowed the Commission to repeal the oxygenated fuels

program for the Fort Collins area, and to remove the automobile testing program from

the SIP. The removal of the automobile testing program from the SIP gives the State the

flexibility to amend or repeal the program later without the delay of the SIP amendment

and approval process. For these reasons, the revisions to the ambient air quality

standard will maximize the air quality benefits of the Commission's regulations in the

most cost- effective manner.

VIII.P. Greeley

Adopted: December 19, 2002

The amendments to the “Ambient Air Quality Standards for the State of Colorado”

Regulation adopted by the Commission establish mobile source emissions budgets for

the Greeley area. The Commission adopted simultaneous revisions to Regulation

Number 13 so that this rule no longer applies in the Greeley area.

Federal Requirements

Nothing in this rule change exceeds the minimum requirements of the federal act.

Statutory Authority

The authority to establish emissions budgets and to establish criteria for transportation

conformity determinations is included in the general authority to adopt a State

Implementation Plan set out in § 25-7-105(1), C.R.S. (2001).

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g in this rule change exceeds the minimum requirements of the federal act.

Statutory Authority

The authority to establish emissions budgets and to establish criteria for transportation

conformity determinations is included in the general authority to adopt a State

Implementation Plan set out in § 25-7-105(1), C.R.S. (2001).

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Findings pursuant to § 25-7-110.8

The mobile source emissions budgets are based on EPA's MOBILE6 emissions model,

as required by federal regulations. All methodologies and information made available by

interested parties have been considered. The emissions budgets reduce the potential

for air pollution by capping emissions from mobile sources. The rule allocates the

margin of safety to mobile sources, thus providing the transportation community with

maximum flexibility authorized by federal law. in adopting this rule, the Commission

chose the most cost-effective alternative.

VIII.Q Denver Carbon Monoxide

Adopted: June 19, 2003

The carbon monoxide emissions budget for the Denver area has been revised to reflect

a new computer model (mobile6) issued by EPA for use in estimating emissions from

motor vehicles. Federal law requires transportation agencies to use such budgets to

make transportation conformity determinations on transportation plans and programs.

40 CFR 93.118. Transportation agencies must use mobile6 for transportation conformity

determinations that begin after January 2004.

Federal Requirements

The revision to the emission budget follows EPA policy established in Policy Guidance

on the Use of Mobile6 for Sip Development and Transportation Conformity (U.S. EPA,

Jan. 18, 2002). The Commission's regulation does not allocate the entire safety margin

to mobile sources, as authorized by federal regulations. Instead, the Commission

reserved a portion of the safety margin in order to preserve a cushion for growth in other

source categories

PA policy established in Policy Guidance

on the Use of Mobile6 for Sip Development and Transportation Conformity (U.S. EPA,

Jan. 18, 2002). The Commission's regulation does not allocate the entire safety margin

to mobile sources, as authorized by federal regulations. Instead, the Commission

reserved a portion of the safety margin in order to preserve a cushion for growth in other

source categories. The reservation of a portion of the safety margin does not mean that

the rule exceeds minimum federal requirements. Instead, the rule merely preserves a

margin of safety for growth in other sources.

Statutory Authority

The Commission adopts this change under its general authority to promulgate and

adopt a state implementation plan, as set out in § 25-7-105(1)(a), C.R.S.

Findings pursuant to § 25-7-110.8. C.R.S.

The purpose of this rule change is to make sure that transportation agencies will use

mobile6-based emissions budgets when making mobile6-based transportation

conformity determinations. The rule change is not intended to reduce air pollution. The

requirements of § 25-7-110.8 do not apply.

VIII.R Longmont and Colorado Springs Carbon Monoxide

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Adopted: December 18, 2003

The carbon monoxide emission budgets for the Longmont and Colorado Springs areas

have been revised to reflect a new computer model (mobile6) issued by EPA for use in

estimating emissions from motor vehicles. Federal law requires transportation agencies

to use such budgets to make transportation conformity determinations on transportation

plans and programs. 40 CFR 93.118. Transportation agencies must use mobile6 for

transportation conformity determinations that begin after January 2004.

Federal Requirements

The revisions to the emission budgets follow EPA policy established in policy guidance

on the use of mobile6 for sip development and transportation conformity (U.S. EPA,

Jan. 18, 2002)

onformity determinations on transportation

plans and programs. 40 CFR 93.118. Transportation agencies must use mobile6 for

transportation conformity determinations that begin after January 2004.

Federal Requirements

The revisions to the emission budgets follow EPA policy established in policy guidance

on the use of mobile6 for sip development and transportation conformity (U.S. EPA,

Jan. 18, 2002). The Commission's regulation allocates the entire safety margin to

mobile sources, as authorized by federal regulations.

Statutory Authority

The Commission adopts this change under its general authority to promulgate and

adopt a state implementation plan, as set out in § 25-7-105(1)(a), C.R.S.

Findings pursuant to § 25-7-110.8. C.R.S.

The purpose of this rule change is to make sure that transportation agencies will use

mobile6-based emissions budgets when making mobile6-based transportation

conformity determinations. The rule change is not intended to reduce air pollution. The

requirements of 25-7-110.8 do not apply.

VIII.S Denver 8-Hour Ozone

Adopted: March 11, 2004

The purpose of this rule change is to define the geographic scope of the Denver 8-hour

Ozone Nonattainment Area for purposes of State Law and Commission regulations.

This definition is not to be included in the state implementation plan.

The Commission adopted this definition in conjunction with the Ozone Action Plan and

certain revisions to of Regulation Number 7 to reduce emissions of volatile organic

compounds from oil and gas operations and from stationary and portable reciprocal

internal combustion engines. Such control measures in Sections XVI, XVI, and XVII VI

of Regulation Number 7 apply in the Denver 8-hour Ozone Nonattainment Area, as

defined in the Ambient Air Quality Standards Regulation.

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ns of volatile organic

compounds from oil and gas operations and from stationary and portable reciprocal

internal combustion engines. Such control measures in Sections XVI, XVI, and XVII VI

of Regulation Number 7 apply in the Denver 8-hour Ozone Nonattainment Area, as

defined in the Ambient Air Quality Standards Regulation.

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The U.S. EPA will also define the geographic scope of the Denver 8-hour Ozone

Nonattainment Area. The Commission intends for its State definition of such area to be

identical to the federal definition. The Commission would ordinarily incorporate the

federal definition by reference but the Commission cannot do that in this case because

EPA has not yet adopted a final rule defining the Denver 8-hour Ozone Nonattainment

Area and will not do so until April 15, 2004 at the earliest. § 24-4-103(12.5), C.R.S.

prohibits the Commission from adopting a later edition of the federal rule. In the event

the area defined by the federal rule is smaller than the area defined by this rule, the

Commission will promptly revise this rule to conform to the federal rule.

The statutory authority to define the nonattainment area is set out in §§ 25-7-105(1)(a)

and (1)(b); 25-7-106(1)(b)(viii), (1)(c) and (5); and 25-7-109(1)(a) and (2), C.R.S.

VIII.T Denver 8-Hour Ozone

Adopted: December 16, 2004

The purpose of this rule change is to revise the geographic scope of the Denver 8-hour

Ozone Nonattainment Area for purposes of State law and Commission regulations.

The revision to the boundaries for the Denver 8-hour ozone control area match the

boundaries promulgated by the Environmental Protection Agency on April 15, 2004. The

initial boundaries matched EPA’s proposed boundaries for the area.

The revisions also include minor, nonsubstantive changes to simplify the language

-hour

Ozone Nonattainment Area for purposes of State law and Commission regulations.

The revision to the boundaries for the Denver 8-hour ozone control area match the

boundaries promulgated by the Environmental Protection Agency on April 15, 2004. The

initial boundaries matched EPA’s proposed boundaries for the area.

The revisions also include minor, nonsubstantive changes to simplify the language.

The statutory authority to define the nonattainment area is set out in §§ 25-7-105(1)(a)

and (1)(b); 25-7-106(1)(b)(VIII), (1)(c) and (5); and 25-7-109(1)(a) and (2), C.R.S.

VIII.U Denver and Longmont Carbon Monoxide Carbon Monoxide, and Denver PM10

Adopted: December 15, 2005

The Commission revised the emissions budgets for carbon monoxide and PM10 for

Denver, as well as the carbon monoxide emissions budget for Longmont. The changes

update the emissions budgets using the latest EPA computer models.

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The Commission has assigned the safety margin for both carbon monoxide and

particulate matter to the mobile source emissions budget, reserving a portion of the

carbon monoxide safety margin in case of additional growth in other sectors beyond the

growth anticipated in the maintenance demonstration. The rule also provides some

flexibility to trade between the NOx and primary particulate budgets for purposes of

transportation conformity determinations. The federal rules allow, but do not require,

assignment of some or the entire safety margin to the transportation conformity budget.

The reservation of a portion of the carbon monoxide safety margin allows for additional

growth in other sectors, but does not make the sip more stringent than the federal

requirements.

The authority to establish emissions budgets is included in the general authority to

adopt a state implementation plan set out in § 25-7-105(1), C.R.S.

The mobile source emissions budgets are based on EPA-approved computer models,

as required by federal regulations

e safety margin allows for additional

growth in other sectors, but does not make the sip more stringent than the federal

requirements.

The authority to establish emissions budgets is included in the general authority to

adopt a state implementation plan set out in § 25-7-105(1), C.R.S.

The mobile source emissions budgets are based on EPA-approved computer models,

as required by federal regulations. All methodologies and information made available by

interested parties have been considered. The rule allocates most of the margin of safety

to mobile sources, but maintains a reasonable margin for accommodation of uncertainty

and future growth in other sectors. The allocation of most of the safety margin to mobile

sources provides flexibility for the transportation community. In adopting this rule, the

Commission chose the most cost-effective option.

VIII.V Cañon City PM10

Adopted: November 20, 2008

The amendments to the “Ambient Air Quality Standards for the State of Colorado”

Regulation adopted by the Commission establish mobile source emissions budgets for

the Cañon City area.

Federal Requirements

Nothing in this rule change exceeds the minimum requirements of the federal act.

Statutory Authority

The authority to establish emissions budgets and to establish criteria for transportation

conformity determinations is included in the general authority to adopt a State

Implementation Plan set out in § 25-7-105(1), C.R.S. (2001).

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g in this rule change exceeds the minimum requirements of the federal act.

Statutory Authority

The authority to establish emissions budgets and to establish criteria for transportation

conformity determinations is included in the general authority to adopt a State

Implementation Plan set out in § 25-7-105(1), C.R.S. (2001).

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Findings pursuant to § 25-7-110.8

The mobile source emissions budgets are based on EPA's MOBILE6 emissions model

and EPA-approved methods for calculating fugitive dust emissions as required by

federal regulations. All methodologies and information made available by interested

parties have been considered. The emissions budgets reduce the potential for air

pollution by capping emissions from mobile sources. In adopting this rule, the

Commission chose the most cost-effective alternative.

Further, these revisions include any typographical, grammatical and formatting errors

throughout the regulation.

VIII.W Denver Metro Area/North Front Range 8-Hour Ozone Emissions Budgets

Adopted December 11, 2008

The amendments to the “Ambient Air Quality Standards for the State of Colorado”

Regulation adopted by the Commission establish mobile source emissions budgets for

the Denver Metro Area/North Front Range 8-Hour Ozone area.

Federal Requirements

Nothing in this rule change exceeds the minimum requirements of the federal act.

Statutory Authority

The authority to establish emissions budgets and to establish criteria for transportation

conformity determinations is included in the general authority to adopt a State

Implementation Plan set out in § 25-7-105(1) and in 25-7-107(1), C.R.S.

Findings pursuant to § 25-7-110.8

The mobile source emissions budgets are based on EPA's MOBILE6 emissions model

and EPA-approved methods for calculating fugitive dust emissions as required by

federal regulations. All methodologies and information made available by interested

parties have been considered

ority to adopt a State

Implementation Plan set out in § 25-7-105(1) and in 25-7-107(1), C.R.S.

Findings pursuant to § 25-7-110.8

The mobile source emissions budgets are based on EPA's MOBILE6 emissions model

and EPA-approved methods for calculating fugitive dust emissions as required by

federal regulations. All methodologies and information made available by interested

parties have been considered. The emissions budgets reduce the potential for air

pollution by capping emissions from mobile sources. In adopting this rule, the

Commission chose the most cost-effective alternative.

VIII.X Pagosa Springs PM10

Adopted November 19, 2009

The amendments to the “Ambient Air Quality Standards for the State of Colorado”

Regulation adopted by the Commission establish mobile source emissions budgets for

the Pagosa Springs PM10 attainment area.

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Federal Requirements

Nothing in this rule change exceeds the minimum requirements of the federal act.

Statutory Authority

The authority to establish emissions budgets and to establish criteria for transportation

conformity determinations is included in the general authority to adopt a State

Implementation Plan set out in § 25-7-105(1), C.R.S. (2001).

Findings pursuant to § 25-7-110.8

The mobile source emissions budgets are based on EPA's MOBILE6 emissions model

and EPA-approved methods for calculating fugitive dust emissions as required by

federal regulations. All methodologies and information made available by interested

parties have been considered. The emissions budgets reduce the potential for air

pollution by capping emissions from mobile sources. In adopting this rule, the

Commission chose the most cost-effective alternative. Further, these revisions will

include any typographical, grammatical and formatting errors throughout the regulation

tions. All methodologies and information made available by interested

parties have been considered. The emissions budgets reduce the potential for air

pollution by capping emissions from mobile sources. In adopting this rule, the

Commission chose the most cost-effective alternative. Further, these revisions will

include any typographical, grammatical and formatting errors throughout the regulation.

VIII.Y Telluride PM10

Adopted November 19, 2009

The amendments to the “Ambient Air Quality Standards for the State of Colorado”

Regulation adopted by the Commission establish mobile source emissions budgets for

the Telluride PM10 attainment area.

Federal Requirements

Nothing in this rule change exceeds the minimum requirements of the federal act.

Statutory Authority

The authority to establish emissions budgets and to establish criteria for transportation

conformity determinations is included in the general authority to adopt a State

Implementation Plan set out in § 25-7-105(1), C.R.S. (2001).

Findings pursuant to § 25-7-110.8

The mobile source emissions budgets are based on EPA's MOBILE6 emissions model

and EPA-approved methods for calculating fugitive dust emissions as required by

federal regulations. All methodologies and information made available by interested

parties have been considered. The emissions budgets reduce the potential for air

pollution by capping emissions from mobile sources. In adopting this rule, the

Commission chose the most cost-effective alternative.

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st emissions as required by

federal regulations. All methodologies and information made available by interested

parties have been considered. The emissions budgets reduce the potential for air

pollution by capping emissions from mobile sources. In adopting this rule, the

Commission chose the most cost-effective alternative.

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Further, these revisions will include any typographical, grammatical and formatting

errors throughout the regulation.

VIII.Z. Ambient Air Quality Standards Regulation Update

Adopted March 18, 2010

The Commission intends to maintain and update its Ambient Air Quality Standards

Regulation.

Statutory Authority

This Statement of Basis, Specific Statutory Authority and Purpose complies with the

requirements of the Colorado Administrative Procedures Act, C.R.S. § 24-4-103, and

the Colorado Air Pollution Prevention and Control Act, C.R.S. §§ 25-7-110, 110.5, and

110.8. Specifically, C.R.S. § 25-7-108 authorizes the Commission to adopt standards for

the quality of ambient air. C.R.S. §§ 25-7-201 and 25-7-209 provide that increases in

pollution concentrations above baseline concentration shall be the same as those

provided for in the federal Clean Air Act.

Basis

Colorado’s Ambient Air Quality Standards Regulation is outdated and unclear.

Purpose

The Commission intends to revise the Ambient Air Quality Standards Regulation by: 1)

removing the ambient air quality standards in the Ambient Air Table in Section II.; 2)

removing the state-only PSD SO2 increments in Section I.B.; and 3) making

administrative changes, including typographical, grammatical and formatting

corrections, as necessary.

Remove Section II. (Ambient Air Table)

The Commission removes the Ambient Air Table in Section II., as it is unnecessary. The

National Ambient Air Quality Standards (NAAQS) are set by EPA. Citizens can get more

current data from EPA

the state-only PSD SO2 increments in Section I.B.; and 3) making

administrative changes, including typographical, grammatical and formatting

corrections, as necessary.

Remove Section II. (Ambient Air Table)

The Commission removes the Ambient Air Table in Section II., as it is unnecessary. The

National Ambient Air Quality Standards (NAAQS) are set by EPA. Citizens can get more

current data from EPA. The EPA maintains a readily available and accessible summary

table of these NAAQS on the internet (see http://epa.gov/air/criteria.html), and the

details of the NAAQS are codified in 40 C.F.R. Part 50, which is also readily available

and accessible on the internet. For these reasons, the Commission removes this

Section II., and references where the information can be found.

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Remove Section I.B. (State-only PSD SO2 Increments)

The Commission removes the state-only incremental ambient air standards for SO2, as

they are artifacts from 1970’s rulemakings that cannot be fully applied per current rules.

The following table compares Colorado’s SO2 increments to the federal SO2

increments.

Colorado SO2 Increments1

Federal SO2 Increments2

Category I

Category II Category III Class I

Class II

Class III

Arithmetic

Mean

2 ug/m3

10 ug/m3

15 ug/m3

2 ug/m3

20 ug/m3

40 ug/m3

24-Hour

Maximum

5 ug/m3

50 ug/m3

100 ug/m3

5 ug/m3

91 ug/m3

182 ug/m3

3-Hour

Maximum

25 ug/m3

300 ug/m3

700 ug/m3

25 ug/m3

512 ug/m3

700 ug/m3

1 See Ambient Air Quality Standards Regulation, Section I.B.

2 See the Clean Air Act, section 163(b), and/or Colorado’s State Implementation Plan – Regulation Number 3, Part D, Section X.A.

Note the distinction between Colorado’s SO2 increment Category areas and the federal

Class areas

/m3

100 ug/m3

5 ug/m3

91 ug/m3

182 ug/m3

3-Hour

Maximum

25 ug/m3

300 ug/m3

700 ug/m3

25 ug/m3

512 ug/m3

700 ug/m3

1 See Ambient Air Quality Standards Regulation, Section I.B.

2 See the Clean Air Act, section 163(b), and/or Colorado’s State Implementation Plan – Regulation Number 3, Part D, Section X.A.

Note the distinction between Colorado’s SO2 increment Category areas and the federal

Class areas. When applicable, Colorado's Category I areas for SO2 were essentially the

same as EPA's Class I area, except that Colorado's Category I areas included some

additional national monuments and forest service primitive areas that would otherwise

be considered as Class II areas. While these former Category I areas for SO2 were

classified as Class II, they were given the protection of the Class I PSD increment for

SO2 only. The remainder of the state was then considered Category II, and now

considered a Class II area. There are no Category III or Class III areas previously or

currently designated in Colorado.

These state-only SO2 increments no longer apply to any area in the state. Early

versions of the Ambient Air Quality Standards Regulation identify Category I, II and III

areas in the state, in which these Colorado SO2 increments applied3.

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However in 1981, in preparation to adopt the federal Prevention of Significant

Deterioration (PSD) rules, a Colorado Increment Task Force met and ultimately made

recommendations on how to adopt the federal PSD Program in Colorado. Co

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