## Of

John W. Hickenlooper, Governor Christopher E. Urbina, MD, MPH

Executive Director and Chief Medical Officer Dedicated to protecting and improving the health and environment of the people of Colorado 4300 Cherry Creek Dr. S. Laboratory Services Division Denver, Colorado 80246-1530 8100 Lowry Blvd. Phone (303) 692-2000 Denver, Colorado 80230-6928 ColoradoDepartment Located in Glendale, Colorado (303) 692-3090 

### ofPublicHealth http://www.cdphe.state.co.us andEnvironment

March 18,2011

James Martin Regional Administrator USEPA Region VIII 1595 Wynkoop Street Denver, CO 80202-1129

RE: 2010 Colorado Designations for I-hour Sulfur DioxideNAAQS

Dear Mr. Martin:

Pursuant to the provisions ofsection 107(d)(1) ofthe Clean Air Act, the state ofColorado submits to the Environmental Protection Agency the attached area designations for the I-Hour Sulfur DioxideNational Ambient Air Quality Standard (NAAQS), as revised on June 2, 2010. Federal law requires that the state ofColorado submit the recommended designations for the I-Hour Sulfur Dioxide NAAQS to the EPA by June 2, 2011, and this letter provides the designations of "attainment" and "attainment/unclassifiable" as applicable for all air quality control regions (AQCRs) in Colorado.

The enclosed technical support document provides a table and map which describes each AQCR and its designation and provides supporting analysis. The technical support document makes a strong case that these designation recommendations are accurate and supportable for EPA approval. The attainment designations for the Denver Metropolitan Area (AQCR 3) are based on actual air quality monitoring data for the 2008-2010 time periods. The attainment/unclassifiable designations for areas lacking representative monitoring are based on the State's estimation that I-Hour Sulfur Dioxide levels in these AQCRs are not out ofcompliance with the I-Hour Sulfur DioxideNAAQS.

RECEIVED U.S. EPA R8tllon 8 RA's Office 

## AR 

## 30 l011

Letter to EPA

- Colorado RecommendedI-HourS02 Designations March 18, 2011The enclosed area classifications for the 2010 I-Hour Sulfur Dioxide NAAQS were adopted by the Colorado Air Quality Control Commission following a public hearing held on March 17, 2011. If you have any questions regarding this submittal, please contact Garry Kaufman, Interim Administrator for the Air Quality Control Commission, at (303) 692-3478 or Paul Tourangeau, Director ofthe Air Pollution Control Division, at (303) 692-3114.

Sincerely,

Christopher E. Urbina, MD, MPH Executive Director and ChiefMedical Officer Colorado Department ofPublic Health and Environment

Enclosure State ofColorado, Technical Support Document for I-Hour Sulfur Dioxide Standard Attainment in Colorado

Letter to EPA

- Colorado Recommended I-Hour S02 Designations March 18, 2011

2

# State ofColorado

Technical Support Document for I-Hour Sulfur Dioxide Standard Attainment in Colorado

March 17,2011 Colorado Department ofPublic Health and Environment Air Pollution Control Division 4300 Cherry Creek Drive South Denver, Colorado 80246

## Contents Designation Recommendation 3 Overview 3 Air Quality Data 3 Figure /. Map of /-Hour Sulfur DioxideAmbientAirMonitoring Sites 2008-20/0 4 Figure 2. Colorado I-Hour Sulfur DioxideAmbientAir Concentration Trends (CDPHE) 5 Figure 3. Colorado I-Hour Sulfur DioxideAmbientAir Concentration Trends (Other) 5 Table I. Colorado I-Hour Sulfur Dioxide Monitoring DataSummary (CDPHE) 6 Table 2. Colorado I-Hour Sulfur Dioxide Monitoring DataSummary (Other) 7 Summary Conclusions 7 Table 3. RecommendedI-Hour Sulfur Dioxide Designations byAreafor Colorado 8 Figure 4. Map of Air Quality ControlRegionsfor I-Hour Sulfur Dioxide Designations in Colorado 10



### Colorado Recommended 1-HourS02 Designations Page 2 

### of 10 Technical SupportDocument March 17, 

### 2011

### Colorado Analysis for I-Hour Sulfur Dioxide Attainment

Designation Recommendation

The State recommends that the entire state ofColorado be designated as attainment or attainmentlunclassifiable for the 2010 revised I-hour sulfur dioxide standard. This reconunendation is based on monitoring information that indicates the region is in compliance with the revised I-hour sulfur dioxide standard.



### Overview

On June 2, 2010, the U.S. Environmental Protection Agency (EPA) promulgated a new National Ambient Air Quality Standard (NAAQS) for sulfur dioxide as a I-hour average. The level was set at 75 ppb as the 3-year average ofthe 99th percentile I-hour daily maximum values. States are required to submit area designation reconunendations to EPA by June 2,2011.

The Air Pollution Control Division (APCD) ofthe Colorado Department ofPublic Health and Environment (CDPHE) currently operates two sulfur dioxide analyzers in Colorado, both in the Denver metropolitan area. All sulfur dioxide monitoring for the 2008-2010 period shows the 3­ year averages ofthe 99th percentile I-hour daily maximum values to be below the level ofthe NAAQS. There are no other known monitoring sites for sulfur dioxide in Colorado that are currently in operation and meet EPA quality assurance criteria. Thus, the APCD is proposing that Colorado be designated as attainment or attainmentlunclassifiable for the entire state (excluding tribal lands over which the APCD has nojurisdiction).

The EPA requires states base their designation recommendations on monitoring data results from the most current complete three year period. The following analysis discusses air quality data as necessary to demonstrate that Colorado should be designated as attainment or attainmentllinclassifiable for the new I-hour sulfur dioxide NAAQS. Itmust also be noted that this attainment demonstration applies only to non-tribal lands over which the State ofColorado has direct air qualityjurisdiction.



### Air Quality Data

The air quality analysis looked at all known monitoring sites for the I-hour sulfur dioxide standard in Colorado for 2008 through 2010. A map ofthe two APCD site locations currently in operation in Colorado (CAMP and Welby) is presented in Figure 1. Other historic sites were also examined.



### Colorado Recommended I-Hour S02 Designations Page 3 of 10 

### Technical Support Document March 17, 2011Figure 2**~resents** l.ong**t~rm tre~ds**  for the APCD's CAMP and Wel,by**s~tes** as the**~~y~ar** average ofthe 991 percentIle daily maximum values, as well as data for a histone APeD sJte (Sottth Adams). It is evident that ambient I-hour sulfurdioxide levels have decreased dl'amaticalfy ()ver time and are now well below the level ofthe new I-hourNAAQS. Much ofthIS decrease is likely due to emissions reductions in major stationary sources and reduced sulfur levels in 

### diesel fuels. Figure 3 presents trends from some historic sites that were operated by Colorado Springs Utilities. While these sites ended operation in 200I, they do provide information that attainment ofthe new I-hourNAAQS is likely in other areas ofColorado.
_Tables I & 2 present a**summar)~** ofthe_99th percentile data for all these sites, as well as the 3­

year average calculations. These tables also indicate years that are not complete for true data assessments, but have been used in this analysis.



### Figure 1. Map of I-HourSulfurDioxideAmbientAirMonitoringSites 2008-2010

Colorado RecommendedI-Hour S02Designations Page 4 

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### Technical Support Document March 17, 2011

### Figure 2. 

### Colorado l-HourSulfurDioxideAmbientAir Concentration Trends (CDPHE) 

## Sulfur dioxide (CDPHE sites) 3-yearaverage of99th percentile i-hourvalues 120

100

NOTE: Partial years onlyfor CAMP for 1999, 2000, 2008 and 2009. Partial year only for South Adams for 2004. 20 40 60**+--------------.:~~=--------------j** c o

cu C. III



## .... III Q. .c

O--'------'-----'---'-----'------'---------'-----'---'--------'----'---------'-----'------'--------'--...L..-...­

...-Welby08-001-3001 _CAMP08-031-0002**~South** Adams 08-001-0007



### Figure 3. Colorado l-HourSulfurDioxideAmbientAir Concentration Trends (Other) 

## Sulfur dioxide (Colo. Spgs. Utilities sites) 3-yearaverage of99th percentile i-hourvalues 120
100 c 

### .9 80 .c 60 cu C. III



## .... 40 III Q. 20 

## I 2010 1-hr.NAAQS



# --------------------------­**.4'-~** t 

# ;<:::

-. NOTE: Partial years onlyfor Colo. Spgs.



# --­ 

# - Utility sites for 2001.**~CSU-Nixon** 08-041-6001_CSU-Pulpit Rock 08-041-6004 -+-CSU-Colo. College 08-041-0011



### Colorado Recommended 1-HourS02Designations Page 

### 5 of 10 Technical SupportDocument March 17, 

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### Table 1. Colorado 1-HourSulfurDioxideMonitorin/!Data Summary (CDPHE)

Year

1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Welby AQS# 08-001-3001 99%ile I-hr. (ppb)

92 76 100 71 94 69 81 56 75 78 58 46 43 37 27 28 33 38

New Standard: 3-yr. Avg. (ppb)

89 82 88 78 81 69 71 70 70 61 49 42 36 31 29 33 CDPHE-APCD 

### sites CAMP AQS# 08-031-0002 99%ile I-hr. (ppb)

117 107 95 101 78 79 67 

### * 78 

### * 71 68 57 33 34 31 33 46 

### * 35 

### *

39 3-yr. Avg. (ppb)

106 101 91 86 75 75 72 72 65 53 41 33 33 37 38 40
3-yr. Avg. ofI-hr. 99th percentile

## =75 ppb South Adams AQS# 08-001-0007 99%i1e I-hr. 3-yr. Avg. (ppb) (ppb)

69 64 36 56 32 

### * 44

NOTE: 

### * 1999,2000,2008,2009 are incompleteyears for CAMP 

### * 2004 is an incomplete yearfor South Adams



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### Technical SupportDocument March 17, 2011

### Table 2. Colorado I-HourSulfurDioxideMonitorinf(Data Summary (Other) Colorado Springs Utilities sites CSU-Nixon CSU-Pulpit Rock CSU-Colo. College AQS# 08-041-6001 AQS# 08-041-6004 AQS# 08-041-6011 99%i1e i-hr. 3-yr. Avg. 99%ile i-hr. 3-yr. Avg. 99%ile i-hr. 3-yr. Avg. Year (ppb) (ppb) (ppb) (ppb) (ppb) (ppb)

1993 58 27 46 1994 51 28 60 1995 53 54 24 26 52 53 1996 45 50 25 26 54 55 1997 55 51 15 21 27 44 1998 43 48 22 21 54 45 1999 55 51 17 18 56 46 2000 39 46 23 21 60 57 2001 39 

### * 44 19 

### * 20 49 

### * 55 (shut down) (shut down) (shut down)

New Standard: 3-yr. Avg. of i-hr. 99th percentile

## =75 ppb

NOTE: 

### * 2001 is an incomplete yearfor CSU-Nixon, CSU-Pulpit Rock, CSU-Colo. College

Summary Conclusions

The data and analysis presented provide documentation and compelling evidence supporting a finding that Colorado should be designated as attainment or attainmentlunclassifiable for the 2010 I-hour sulfur dioxide NAAQS. Itis important to note that only areas over which Colorado has direct air qualityjurisdiction are included in this attainment attainmentlunclassifiable finding and recommendation. The Southern Ute Indian Tribe, and the Southern Ute Indian Tribe/State of Colorado Environmental Commission, as well as the Ute Mountain Ute Indian Tribe, are distinct nations or entities and consequently such Tribal lands are specifically excluded from this designation recommendation.

Table 3 provides a complete listing ofthe recommended designations, by area. Figure 4 provides
a map ofthe Air Quality Control Regions for the I-hour sulfur dioxide designations in Colorado. These recommendations are based on current monitoring information that indicates compliance with the revised standard.

Colorado Recommended I-Hour S02 Designations Page 7 of10 Technical SupportDocument March 17.2011

### Table 3. 

### RecommendedI-HourSulfurDioxideDesignations byArea/or Colorado
2010 Colorado Designations forthe 1-Hour Sulfur Dioxide NAAQS (based on 2007-2009 monitoring data)

Air Quality Control Regions (AQCR) Sulfur Dioxide NAAQS Designation State AQCR 01 Logan County Morgan County Phillips County Sedgwick County Washington County Yuma County AttainmentiUnciassifiable

State AQCR 02 Larimer County Weld County AttainmentiUnclassifiable

State AQCR 03 Adams County Arapahoe County Boulder County (including the portion of Rocky Mountain National Park therein) Broomfield County Clear Creek County Denver County Douglas County Jefferson County Gilpin County Attainment

State AQCR 04 AttainmentiUnclassifiable EI Paso County Park County Teller County
State AQCR 05 Cheyenne County Elbert County Kit Carson County Lincoln County AttainmentiUnclassifiable

State AQCR 06 AttainmentiUnclassifiable Baca County Bent County Crowley County Kiowa County Otero County Prowers County
State AQCR 07 Huerfano County Las Animas County Pueblo County Attainment/Unclassifiable

Colorado Recommended 1-Hour

### S02Designations Page 

### 8 of 10 Technical SupportDocument March 17, 20112010 Colorado Designations for the 1-Hour Sulfur Dioxide NAAQS (based on 2007-2009 monitoring data)

Air Quality Control Regions (AQCR) Sulfur Dioxide NAAQS Designation State AQCR 08 Alamosa County Conejos County Costilla County Mineral County Rio Grande County Saguache County AttainmentlU nclassifiable

State AQCR 09 Archuleta County (part) excluding Southern Ute Indian Tribe (SUIT) lands Dolores County La Plata County (part) excluding SUIT and Ute Mountain Ute Tribe lands Montezuma County (part) excluding SUIT and Ute Mountain Ute Tribe lands San Juan County AttainmentlUnciassifiable

State AQCR 10 Delta County Gunnison County Hinsdale County Montrose County Ouray County San Miguel County AttainmentlUnciassifiable

State AQCR 11 Garfield County Mesa County Moffat County Rio Blanco County AttainmentlUnclassifiable

State AQCR 12 AttainmentlUnciassifiable Eagle County Grand County Jackson County Pitkin County Routt County Summit County
State AQCR 13 AttainmentlUnciassifiable Chaffee County Custer County Fremont County Lake County

Colorado Recommended I-Hour S02 Designations Page 

### 9 of 10 Technical Support Document March 17, 2011

### Figure 4. 

### Map

## 0/ AirQuality ControlRegions/orI-HourSulfurDioxideDesignations in Colorado

S02 Monitoring Site c:l Colorado Air auality Comrol Regions CitiesfTowns 0 Counties AQCR 1

A CR 5

AQCR 6

Colorado Oepartmem of Puhlrc Health and E",;ronment

. Air Pollution Control or,;sion Legend

(;)



### Colorado Recommended I-Hour S02Designations Page 10 

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### Technical Support Document March 17, 2011