42346 Federal Register / Vol. 75, No. 139 / Wednesday, July 21, 2010 / Proposed Rules 

of the Paperwork Reduction Act (44 

U.S.C. 3501 et seq.); 

• Is certified as not having a 

significant economic impact on a 

substantial number of small entities 

under the Regulatory Flexibility Act (5 

U.S.C. 601 et seq.); 

• Does not contain any unfunded 

mandate or significantly or uniquely 

affect small governments, as described 

in the Unfunded Mandates Reform Act 

of 1995 (Public Law 104–4); 

• Does not have Federalism 

implications as specified in Executive 

Order 13132 (64 FR 43255, August 10, 

1999); 

• Is not an economically significant 

regulatory action based on health or 

safety risks subject to Executive Order 

13045 (62 FR 19885, April 23, 1997); 

• Is not a significant regulatory action 

subject to Executive Order 13211 (66 FR 

28355, May 22, 2001); 

• Is not subject to requirements of 

Section 12(d) of the National 

Technology Transfer and Advancement 

Act of 1995 (15 U.S.C. 272 note) because 

application of those requirements would 

be inconsistent with the Clean Air Act; 

and 

• Does not provide EPA with the 

discretionary authority to address, as 

appropriate, disproportionate human 

health or environmental effects, using 

practicable and legally permissible 

methods, under Executive Order 12898 

(59 FR 7629, February 16, 1994). 

In addition, this rule does not have 

tribal implications as specified by 

Executive Order 13175 (65 FR 67249, 

November 9, 2000), because the SIP is 

not approved to apply in Indian country 

located in the state, and EPA notes that 

it will not impose substantial direct 

costs on tribal governments or preempt 

tribal law. 

List of Subjects in 40 CFR Part 52 

Environmental protection, Air 

pollution control, Carbon monoxide, 

Intergovernmental relations, Lead, 

Nitrogen dioxide, Ozone, Particulate 

matter, Reporting and recordkeeping 

requirements, Sulfur oxides, Volatile 

organic compounds. 

Authority: 42 U.S.C. 7401 et seq. 

Dated: July 12, 2010. 

Carol Rushin, 

Deputy Regional Administrator, Region 8. 

[FR Doc. 2010–17790 Filed 7–20–10; 8:45 am] 

BILLING CODE 6560–50–P 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 52 

[EPA–R08–OAR–2010–0285; FRL–9177–2] 

Approval and Promulgation of Air 

Quality Implementation Plans; 

Colorado; Attainment Demonstration 

for the 1997 8-Hour Ozone Standard, 

and Approval of Related Revisions 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Proposed rule. 

SUMMARY: EPA is proposing to act on 

proposed revisions to Colorado’s State 

Implementation Plan (SIP). On June 18, 

2009, Colorado submitted proposed SIP 

revisions intended to ensure attainment 

of the 1997 ozone National Ambient Air 

Quality Standards (NAAQS) in the 

Denver Metro Area/North Front Range 

nonattainment area by 2010. The June 

18, 2009 submittal consists of an ozone 

attainment plan, which includes 

emission inventories, a modeled 

attainment demonstration using 

photochemical grid modeling, a weight 

of evidence analysis, and 2010 motor 

vehicle emissions budgets for 

transportation conformity. The 

submittal also includes revisions to 

Colorado Regulation Numbers 3 and 7 

and to Colorado’s Ambient Air Quality 

Standards Regulation. EPA is proposing 

to approve the attainment 

demonstration, the rest of the ozone 

attainment plan, with limited 

exceptions, and the revisions to 

Colorado Regulation Number 3, Parts A 

and B. EPA is proposing to approve 

portions of the revisions to Colorado 

Regulation Number 7 and to disapprove 

other portions. EPA is proposing to 

disapprove Colorado Regulation 

Number 3, Part C, and Colorado’s 

Ambient Air Quality Standards 

Regulation. EPA is proposing to 

disapprove limited portions of the 

ozone attainment plan. EPA is 

proposing these actions pursuant to 

section 110 and part D of the Clean Air 

Act (CAA) and EPA’s regulations. 

DATES: Comments must be received on 

or before August 20, 2010. 

ADDRESSES: Submit your comments, 

identified by Docket ID Regulation 

Number EPA–R08–OAR–2010–0285, by 

one of the following methods: 

• http://www.regulations.gov. Follow 

the on-line instructions for submitting 

comments. 

• E-mail: kenney.james@epa.gov. 

• Fax: (303) 312–6064 (please alert 

the individual listed in the FOR FURTHER

INFORMATION CONTACT if you are faxing 

comments). 

• Mail: James Kenney, Air Program, 

EPA Region 8, Mailcode 8P–AR, 1595 

Wynkoop St., Denver, Colorado 80202– 

1129. 

• Hand Delivery: James Kenney, Air 

Program, EPA, Region 8, Mailcode 8P– 

AR, 1595 Wynkoop St., Denver, 

Colorado 80202–1129. Such deliveries 

are only accepted Monday through 

Friday, 8 a.m. to 4:30 p.m., excluding 

Federal holidays. Special arrangements 

should be made for deliveries of boxed 

information. 

Instructions: Direct your comments to 

Docket ID Regulation Number EPA– 

R08–OAR–2010–0285. EPA’s policy is 

that all comments received will be 

included in the public docket without 

change and may be made available 

online at http://www.regulations.gov, 

including any personal information 

provided, unless the comment includes 

information claimed to be Confidential 

Business Information (CBI) or other 

information whose disclosure is 

restricted by statute. Do not submit 

information that you consider to be CBI 

or otherwise protected through http:// 

www.regulations.gov or e-mail. The 

http://www.regulations.gov web site is 

an ‘‘anonymous access’’ system, which 

means EPA will not know your identity 

or contact information unless you 

provide it in the body of your comment. 

If you send an e-mail comment directly 

to EPA, without going through http:// 

www.regulations.gov, your e-mail 

address will be automatically captured 

and included as part of the comment 

that is placed in the public docket and 

made available on the Internet. If you 

submit an electronic comment, EPA 

recommends that you include your 

name and other contact information in 

the body of your comment and with any 

disk or CD–ROM you submit. If EPA 

cannot read your comment due to 

technical difficulties and cannot contact 

you for clarification, EPA may not be 

able to consider your comment. 

Electronic files should avoid the use of 

special characters, any form of 

encryption, and be free of any defects or 

viruses. For additional information 

about EPA’s public docket, visit the EPA 

Docket Center homepage at http:// 

www.epa.gov/epahome/dockets.htm. 

Docket: All documents in the docket 

are listed in the http:// 

www.regulations.gov index. Although 

listed in the index, some information is 

not publicly available, e.g., CBI or other 

information whose disclosure is 

restricted by statute. Certain other 

material, such as copyrighted material, 

will be publicly available only in hard 

copy. Publicly available docket 

materials are available either 

electronically in http:// 


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www.regulations.gov or in hard copy at 

the Air Program, EPA Region 8, 1595 

Wynkoop Street, Denver, Colorado 

80202–1129. EPA requests that if at all 

possible, you contact the individual 

listed in the FOR FURTHER INFORMATION

CONTACT section to view the hard copy 

of the docket. You may view the hard 

copy of the docket Monday through 

Friday, 8 a.m. to 4 p.m., excluding 

Federal holidays. 

FOR FURTHER INFORMATION CONTACT: 

James C. Kenney, Air Program, EPA 

Region 8, Mailcode 8P–AR, 1595 

Wynkoop St., Denver, Colorado 80202– 

1129, phone (303) 312–6176, e-mail 

kenney.james@epa.gov. 

SUPPLEMENTARY INFORMATION: 

Definitions 

For the purpose of this document, we 

are giving meaning to certain words or 

initials as follows: 

• The words or initials Act or CAA 

mean or refer to the Clean Air Act, 

unless the context indicates otherwise. 

• The words EPA, we, us or our mean 

or refer to the United States 

Environmental Protection Agency. 

• The initials SIP mean or refer to 

State Implementation Plan. 

• The words Colorado and State 

mean the State of Colorado. 

Table of Contents 

I. General Information 

II. What action is EPA proposing? 

III. What is the background of this action? 

IV. What is EPA’s evaluation of the SIP 

revision? 

A. Procedural Requirements 

B. Monitoring 

C. Emission Inventories 

D. Photochemical Grid Modeling 

E. Modeled Attainment Demonstration 

F. Weight of Evidence 

G. Specific OAP Language 

H. SIP Control Measures 

I. Transportation Conformity 

V. Consideration of Section 110(l) of the CAA 

VI. Proposed Action 

VII. Statutory and Executive Order Reviews 

I. General Information 

What should I consider as I prepare my 

comments for EPA? 

1. Submitting CBI: Do not submit CBI 

to EPA through http:// 

www.regulations.gov or e-mail. Clearly 

mark the part or all of the information 

that you claim to be CBI. For CBI 

information in a disk or CD ROM that 

you mail to EPA, mark the outside of the 

disk or CD ROM as CBI and then 

identify electronically within the disk or 

CD ROM the specific information that is 

claimed as CBI. In addition to one 

complete version of the comment that 

includes information claimed as CBI, a 

copy of the comment that does not 

contain the information claimed as CBI 

must be submitted for inclusion in the 

public docket. Information so marked 

will not be disclosed except in 

accordance with procedures set forth in 

the Code of Federal Regulations (CFR) 

pursuant to 40 CFR part 2. 

2. Tips for Preparing Your Comments: 

When submitting comments, remember 

to: 

• Identify the rulemaking by docket 

number and other identifying 

information (subject heading, Federal 

Register date and page number). 

• Follow directions—The agency may 

ask you to respond to specific questions 

or organize comments by referencing a 

CFR part or section number. 

• Explain why you agree or disagree; 

suggest alternatives and substitute 

language for your requested changes. 

• Describe any assumptions and 

provide any technical information and/ 

or data that you used. 

• If you estimate potential costs or 

burdens, explain how you arrived at 

your estimate in sufficient detail to 

allow for it to be reproduced. 

• Provide specific examples to 

illustrate your concerns, and suggest 

alternatives. 

• Explain your views as clearly as 

possible, avoiding the use of profanity 

or personal threats. 

• Make sure to submit your 

comments by the comment period 

deadline identified. 

II. What action is EPA proposing? 

As enumerated below, EPA is 

proposing various actions on Colorado’s 

proposed revisions to its State 

Implementation Plan (SIP) that it 

submitted to EPA on June 18, 2009, to 

ensure attainment of the 1997 ozone 

National Ambient Air Quality Standards 

(NAAQS) in the Denver Metro Area/ 

North Front Range (DMA/NFR) 

nonattainment area. The DMA/NFR 

nonattainment area includes Adams, 

Arapahoe, Boulder, Broomfield, Denver, 

Douglas, and Jefferson Counties, and 

portions of Larimer and Weld Counties 

(40 CFR 81.306). 

Colorado’s proposed SIP revisions 

consist of the following parts: 

• 8-Hour Ozone Attainment Plan 

(OAP), which includes monitoring 

information, emission inventories, a 

modeled attainment demonstration 

using photochemical grid modeling, a 

weight of evidence analysis, and 2010 

motor vehicle emissions budgets 

(MVEBs) for transportation conformity. 

• Revisions to Regulation Number 3, 

Parts A, B, and C. 

• Revisions to Regulation Number 7. 

• Revisions to Colorado’s Ambient 

Air Quality Standards Regulation. 

We are proposing to approve 

Colorado’s 2010 attainment 

demonstration for the 1997 8-hour 

ozone NAAQS. We are proposing to 

approve the motor vehicle emissions 

budgets contained in the OAP. We are 

proposing to approve all other aspects of 

the OAP, with the following limited 

exceptions: we are proposing to 

disapprove the last paragraph on page 

IV–1 and the first paragraph on page IV– 

2 of the OAP, we are proposing to 

disapprove the words ‘‘federally 

enforceable’’ in the second to last 

paragraph on page V–6 of the OAP, and 

we are proposing to disapprove the 

reference to Attachment A in the OAP’s 

Table of Contents and on page IV–3 of 

the OAP. 

We are proposing to approve the 

revisions to Colorado Regulation 

Number 3, Parts A and B. We are 

proposing to disapprove the revisions to 

Colorado Regulation Number 3, Part C. 

We are proposing to approve the 

following portions of the revisions to 

Colorado Regulation Number 7: 

• Revisions to Sections I through XI, 

except for Colorado’s repeal of Section 

II.D. 

• Revisions to Sections XIII through 

XVI. 

We are proposing to disapprove the 

following portions of the revisions to 

Colorado Regulation Number 7: 

• Colorado’s proposed repeal of 

Section II.D. 

• Revisions to Section XII. 

We are proposing to disapprove the 

revisions to Colorado’s Ambient Air 

Quality Standards Regulation. 

The provisions we are proposing to 

approve meet the requirements of the 

CAA and our regulations, including 40 

CFR 81.300(e)(3)(ii)(D). The provisions 

we are proposing to disapprove are 

inconsistent with CAA requirements 

and our regulations. The specific bases 

for our proposed actions and our 

analyses and findings are discussed in 

this proposed rulemaking. Technical 

information that we rely upon in this 

proposal is contained in the State’s 

technical support document (TSD). The 

TSD is available on-line at http:// 

www.regulations.gov, Docket No. EPA– 

R08–OAR–2010–0285. 

III. What is the background of this 

action? 

On July 18, 1997, EPA promulgated a 

revised 8-hour ozone standard of 0.08 

parts per million (ppm) (62 FR 38855). 

Ozone is formed from the 

photochemical reaction of nitrogen 

oxides (NOX) with volatile organic 

compounds (VOCs). Under EPA 

regulations (40 CFR part 50, Appendix 

I), the 1997 0.08 ppm 8-hour ozone 


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1State revisions to the SIP do not become 

federally effective unless and until they are 

approved by EPA. 40 CFR 51.105. 

NAAQS is attained when the 3-year 

average of the annual fourth highest 

daily maximum 8-hour average ambient 

ozone concentrations is less than or 

equal to 0.08 ppm. Forty CFR part 50, 

Appendix I, section 2.3, directs that the 

third decimal place of the computed 3- 

year average be rounded, with values 

equal to or greater than 0.005 rounding 

up. Thus, under our regulations, a 

computed 3-year average ozone 

concentration of 0.085 ppm is the 

smallest value that is considered to be 

greater than 0.08 ppm and a violation of 

the standard. 

On April 30, 2004, we designated 

areas as attaining or not attaining the 

1997 8-hour ozone NAAQS. As part of 

that rule, we deferred the effective date 

of a designation as nonattainment for 

multiple areas of the country, including 

the DMA/NFR area. These areas, which 

were called Early Action Compact 

(EACs) areas, agreed to follow a program 

to achieve early reduction of emissions 

necessary to attain the 1997 8-hour 

standard in order to attain that standard 

no later than December 31, 2007 (69 FR 

23857). Because the DMA/NFR area 

violated the 1997 8-hour standard 

during the summer of 2007, the 

nonattainment designation for the area 

became effective on November 20, 2007. 

Our regulations addressing EAC areas 

that failed to attain the 1997 8-hour 

ozone standard by December 31, 2007 

(40 CFR § 81.300(e)(3)(ii)(D)) required 

that Colorado submit an attainment 

demonstration SIP for the 1997 8-hour 

standard. Colorado submitted its revised 

attainment demonstration SIP for the 

DMA/NFR area on June 18, 2009. 

IV. What is EPA’s evaluation of the SIP 

revision? 

A. Procedural Requirements 

The CAA requires that states meet 

certain procedural requirements before 

submitting SIP revisions to EPA. 

Specifically, section 110(a)(2) of the 

CAA requires that states adopt SIP 

revisions after reasonable notice and 

public hearing. 

The Colorado Air Quality Control 

Commission (AQCC) provided notice in 

the Colorado Register on October 10, 

2008 and held a public hearing on the 

SIP revision on December 11 and 12, 

2008. The Colorado AQCC adopted the 

SIP revision on December 12, 2008. The 

SIP revision became State effective on 

January 30, 2009.1 Colorado met the 

CAA’s procedural requirements for 

reasonable notice and public hearing. 

B. Monitoring 

The monitoring section of the OAP 

provides information with respect to the 

location of ozone monitors in Colorado 

(from southern Metropolitan Denver to 

northern Fort Collins, including Rocky 

Mountain National Park); the State’s 

ambient air quality data assurance 

program; a description and commitment 

for continued operation of the ozone 

monitoring network; and relevant 8- 

hour average ozone monitoring data and 

recovery rates from 2000 through 

September 2008. 

Ozone monitoring data was collected 

following 40 CFR part 58; EPA’s 

‘‘Quality Assurance Handbook for Air 

Pollution Measurement Systems, Vol. 

II—Ambient Air Quality Monitoring 

Program’’; the Colorado Air Pollution 

Control Division’s (APCD) Quality 

Management Plan and Quality 

Assurance Project Plan documents; and 

Colorado’s Federally-approved 

monitoring SIP (September, 23, 1993, 58 

FR 49435). 

Data for 2005–2007 and 2006–2008 

reflect violations of the 8-hour ozone 

NAAQS at the Rocky Flats North 

monitor (values of 0.085 and 0.086 ppm, 

respectively). Monitoring data are used 

as a basis for photochemical grid 

modeling in the attainment 

demonstration, a process described 

below. In the OAP, Colorado indicates 

that it will continue to operate an 

appropriate air quality monitoring 

network in accordance with 40 CFR part 

58. 

C. Emissions Inventories 

In the OAP, Colorado presents three 

different emissions inventories for the 

DMA/NFR nonattainment area: 2006 

base case, 2010 base case, and 2010 

control case. The inventories, in tons 

per summer day, represent emissions 

estimates for all source categories 

during a typical summer day when 

ozone formation is pronounced. The 

emissions inventories catalog NOX and 

VOC emissions because these pollutants 

are precursors to ozone formation. 

The 2006 base case inventory is the 

‘‘base year’’ inventory for the attainment 

demonstration. Base year inventories are 

developed to help determine the 

emissions reductions needed to 

demonstrate attainment of the NAAQS. 

A base year emissions inventory serves 

as the starting point for attainmentdemonstration air quality modeling and 

for determining the need for additional 

SIP control measures. 

Using 2006 as the base year emissions 

inventory ensures that the inventory 

reflects one of the years used for 

calculating the design value that 

resulted in the area’s nonattainment 

designation. The design value is the 3- 

year average of the annual fourth 

highest daily maximum 8-hour average 

ozone concentration (see 40 CFR part 

50, Appendix D). In Colorado’s case, the 

Denver area was violating the ozone 

standard during the period of 2005– 

2007, and, therefore, the nonattainment 

designation became effective. 

The 2010 base case emissions 

inventory assumes the same federally 

enforceable control measures that were 

in place in 2006 and all federally 

enforceable control measures that 

became effective after 2006. These 

control measures are described at pages 

III–1 through III–3 of the OAP. As 

described in greater detail below, 

Colorado was able to demonstrate 

attainment in 2010 based on the 2010 

base case emissions inventory. 

The 2010 control case emissions 

inventory assumes the adoption and 

implementation of additional control 

measures beyond the measures assumed 

for the 2010 base case. These additional 

control measures are described at page 

V–10 of the OAP (2008 State-only 

revisions to Regulation Number 11 that 

tightened tailpipe standards, 2008 Stateonly revisions to Regulation Number 7 

that required low-bleed devices for 

pneumatic controllers, an increase in 

the system-wide reduction of 

condensate tank VOC emissions from 

75% to 81% in 2010, and 7.8 psi RVP 

gasoline in the NFR area). While 

Colorado was able to demonstrate 

attainment without these additional 

control measures, Colorado modeled the 

2010 control case emissions inventory 

to determine whether additional 

reductions in ozone precursors (NOX

and VOCs) beyond the 2010 base case 

would result in further reductions of 

ozone. 

The three emissions inventories 

discussed above (i.e., 2006 base case 

emissions inventory, 2010 base case 

emissions inventory, and the 2010 

control case emissions inventory) were 

developed using EPA-approved 

guidelines for stationary, mobile, and 

area/off-road emission sources. Point 

source emissions data were self-reported 

to the State by individual sources. Onroad mobile source emissions data were 

estimated using EPA models (MOBILE6) 

and Vehicle Miles Traveled (VMT) data. 

Area/off-road vehicle emissions were 


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developed using demographic 

information. Future emissions were 

projected through the use of economic 

growth modeling and analysis. Table 1 

shows the emissions by source category, 

in tons per day (tpd), from the three 

emission inventories. 

TABLE 1—EMISSIONS INVENTORY DATA FOR SPECIFIC SOURCE CATEGORIES

Source Category (tons/avg. episode day) 

2006 Base 2010 Base 2010 Control 

NOX VOC NOX VOC NOX VOC 

Point Sources: 

Electric Generation Units .......................................................................................... 55.6 0.7 58.5 1.6 58.5 1.6 

External Combustion Boilers .................................................................................... 9.5 0.4 10.0 0.5 10.0 0.5 

Industrial Processes ................................................................................................. 12.5 10.2 14.0 11.0 14.0 11.0 

Petroleum and Solvent Evaporation ......................................................................... 0.3 19.0 0.3 22.0 0.3 22.0 

Other ......................................................................................................................... 3.1 1.8 3.6 2.0 3.6 2.0 

Point Sources Subtotal ...................................................................................... 81.0 32.1 86.4 37.0 86.4 37.0 

Oil and Gas Point & Area Sources: 

Condensate Tanks .................................................................................................... ............ 126.5 ............ 129.6 ............ 105.6 

Other O&G Point Sources ........................................................................................ 22.6 6.8 23.6 8.6 23.6 8.6 

Pneumatic Devices (Area Source) ........................................................................... ............ 24.8 ............ 31.1 ............ 12.0 

Unpermitted Fugitives (Area Sources) ..................................................................... ............ 16.2 ............ 20.4 ............ 20.4 

Other Area Sources .................................................................................................. 17.1 10.8 22.5 13.7 22.5 13.7 

O&G Point & Area Sources Subtotal ................................................................ 39.7 185.2 46.2 203.3 46.2 160.1 

Area Sources 

Personal Care Products ........................................................................................... ............ 7.1 ............ 7.0 ............ 7.0 

Household Products ................................................................................................. ............ 21.4 ............ 17.9 ............ 17.9 

Automotive Aftermarket Products ............................................................................. ............ 11.9 ............ 13.0 ............ 13.0 

Architectural Coatings ............................................................................................... ............ 20.1 ............ 16.8 ............ 16.8 

Aircraft ....................................................................................................................... 7.4 1.3 8.2 1.5 8.2 1.5 

Railroad ..................................................................................................................... 12.8 0.5 13.8 0.6 13.8 0.6 

Other Coatings/Pesticides/Cooking/Misc .................................................................. ............ 3.9 ............ 4.1 ............ 4.1 

Area Source Subtotal ........................................................................................ 20.2 66.3 22.1 61.0 22.1 61.0 

Non-Road Mobile Sources: 

Agricultural Equipment .............................................................................................. 7.0 0.9 6.3 0.7 6.3 0.7 

Airport Equipment ..................................................................................................... 0.7 0.1 0.6 0.1 0.6 0.1 

Commercial Equipment ............................................................................................ 5.3 6.2 5.1 7.0 5.1 7.0 

Construction and Mining Equipment ........................................................................ 35.7 5.5 31.2 4.5 31.2 4.5 

Industrial Equipment ................................................................................................. 10.5 2.4 6.9 1.4 6.9 1.4 

Lawn and Garden Equip. (Commercial) ................................................................... 9.4 35.9 8.9 28.1 8.9 28.1 

Lawn and Garden Equip. (Residential) .................................................................... 1.2 7.5 1.2 11.8 1.2 11.8 

Boats/Recreational Equip/Misc ................................................................................. 0.7 6.9 0.8 7.8 0.8 7.8 

Non-Road Mobile Source Subtotal .................................................................... 70.5 65.3 61.0 61.3 61.0 61.3 

On-Road Mobile Sources Subtotal .................................................................... 165.5 129.7 122.9 109.2 118.9 106.0 

Anthropogenic Subtotal ..................................................................................... 376.8 478.6 338.5 471.8 334.6 425.4 

Biogenic Subtotal ............................................................................................... 53.0 694.0 53.0 694.0 53.0 694.0 

Total ............................................................................................................ 429.8 1172.6 391.5 1165.8 387.6 1119.4 

Colorado employed EPA guidelines 

for rule effectiveness when preparing 

these emission inventories. Rule 

effectiveness, expressed as a percentage, 

represents the ability of a regulatory 

program to control point sources to 

achieve emissions reductions. Based on 

control strategies for the oil and gas 

source category, Colorado used 83 

percent for rule effectiveness. A rule 

effectiveness of 83 percent discounts the 

emissions reductions from the control 

measures by 17 percent. Based on 

Colorado’s analysis, which considered 

compliance rates with existing control 

measures, EPA finds that a value of 83 

percent is reasonable for rule 

effectiveness for oil and gas control 

measures. For further detail regarding 

Colorado’s analysis, the reader should 

refer to Colorado’s TSD. 

For oil and gas point and area sources, 

the 2010 control case inventory reflects 

a 43.2 tpd reduction in VOC emissions 

as compared to the 2010 base case 

inventory. For on-road mobile sources, 

the 2010 control case inventory reflects 

a 3.2 tpd reduction in VOC emissions as 

compared to the 2010 base case 

inventory. 

D. Photochemical Grid Modeling 

Colorado conducted photochemical 

grid modeling (hereafter referred to as 

‘‘modeling’’) to demonstrate that the 

emissions control strategy leads to 

attainment of the NAAQS by 2010. The 

modeling followed EPA’s 

photochemical modeling guidance 

(Guidance on the Use of Models and 

Other Analyses for Demonstrating 

Attainment of Air Quality Goals for 


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Ozone, PM2.5, and Regional Haze, EPA– 

454/B–07–002, April 2007). 

The attainment demonstration 

modeling utilized the Comprehensive 

Air-quality Model with extensions 

(CAMx), Sparse Matrix Operating 

Kernel Emissions (SMOKE) system, and 

Mesoscale Model 5 (MM5). Colorado 

applied these models to data from June 

2006 and July 2006. These models were 

set up using a nested 36/12/4 kilometer 

(km) domain structure. The 36 km 

domain covering most of North America 

was used to generate boundary 

conditions (BCs) for the 12 km modeling 

domain. CAMx was then used to 

simulate ozone formation within the 12/ 

4 km modeling domain. The CAMx 

simulation, sensitivity, and control 

strategy evaluations runs were made on 

the 12/4 km modeling domain. 

EPA guidance recommends that 

model performance be tested against 

certain performance goals. Model 

performance testing is used to 

determine the model’s reliability in 

projecting future year ozone 

concentrations. Using meteorological 

and emissions data from a historical 

base period, ozone concentrations 

predicted by the model are compared to 

monitored ozone concentrations to 

determine model performance. 

EPA’s modeling guidance emphasizes 

the use of graphical and diagnostic 

evaluation techniques to assure that the 

modeling captures the correct chemical 

regimes and emission sources that result 

in high ozone concentrations (i.e., 

assuring that the model is getting the 

right answer for the right reason). 

Colorado’s model performance 

evaluation included such graphical and 

diagnostic evaluation techniques. In 

addition, EPA modeling guidance 

includes three numerical performance 

goals that are useful in evaluating ozone 

models as part of the attainment 

demonstration. These include: unpaired 

accuracy of the peak ≤±20%; normalized 

mean bias ≤±15%; and normalized mean 

gross error ≤35%. 

Using a June 1 through July 30, 2006 

episode period, Colorado calculated the 

mean normalized bias and gross error 

statistical measures using all the 

predicted and observed hourly ozone 

pairs, matched by time and location, for 

which the observed ozone was equal to 

or greater than 0.060 ppm. The 

evaluation showed that the modeling 

achieved the ‘‘Unpaired Accuracy of the 

Peak’’ performance goal of ≤±20% for 58 

of the 60 simulation days of the episode 

(i.e., 97% of the modeled days). There 

were 58 days rather than 60 with bias 

and error comparisons during the 

episode period because two days had no 

observed ozone values greater than 

0.060 ppm; thus, no statistics could be 

calculated for those two days. Of the 58 

days, 50 days (or 86%) achieved EPA’s 

≤±15% performance for mean 

normalized bias and all of them 

achieved EPA’s performance goal for 

mean normalized gross error. 

The CAMx model also exhibited very 

good agreement for VOC/NOX ratios on 

most days, indicating that the model 

was simulating the correct chemical 

regimes. The performance of the CAMx 

model in predicting ozone 

concentrations, and precursor 

concentrations, met EPA’s guidelines for 

model performance. The model outputs 

were consistent with the day-to-day 

patterns of observed data, with low bias 

and error. EPA concurs with Colorado’s 

assessment that the model was properly 

set up, met EPA performance 

requirements, and was appropriately 

used in its application. 

E. Modeled Attainment Demonstration 

The modeled attainment 

demonstration for ozone is one in which 

model estimates are used in a relative 

sense rather than absolute sense. That 

is, we take the ratio of the model’s 

future (2010) to current (2006) 

predictions at ozone monitors in the 

DMA/NFR area. We call these ratios 

‘‘Relative Response Factors’’ (RRFs). 

Future ozone concentrations are 

estimated at existing monitoring sites by 

multiplying a modeled RRF at locations 

near each monitor by the observationbased, monitor-specific, baseline design 

value. The resulting predicted future 

concentrations are then compared with 

the 1997 0.08 ppm 8-hour ozone 

NAAQS. If the predicted future 

concentrations of ozone are lower than 

0.08 ppm at all monitors, attainment is 

demonstrated. The test for ozone is 

based on the calculation of a single 

mean ozone RRF for each monitor. 

Table 2, below, summarizes the 

estimated concentrations within the 

Colorado 4 km grid domain for 

Colorado’s 2006 base case, 2010 base 

case, and final 2010 control measure 

case modeling. The final 2010 control 

measure case is not the same as the 2010 

control case discussed in section III.C of 

this action, above. Unlike the 2010 

control case, the final 2010 control 

measure case does not include emission 

reductions from State-only measures. 

Also, at the time Colorado prepared the 

2010 control case inventory, the AQCC 

had not yet adopted final changes to 

Regulation Number 7. The final changes 

included greater system-wide 

condensate tank VOC reductions in 

2010—85% instead of 81%—and 

additional control requirements. 

Colorado used the final adopted version 

of Regulation Number 7 to create a final 

2010 control measure case inventory 

and then modeled that inventory. For 

further details, see page V–7 of the OAP 

and Appendix I of Colorado’s TSD. 

Table 2, below, displays three 

scenarios: (1) 2005–2007 8-hour ozone 

concentration Current Design Values 

(DVC); (2) projected 2010 base case 8- 

hour ozone concentration Future Design 

Values (DVF); and (3) final 2010 control 

measure case 8-hour ozone 

concentration DVFs. Per EPA guidance, 

the first set of DVFs in Table 2 (columns 

4 and 5) are shown in ppm to the third 

decimal place, with additional digits to 

the right truncated, for comparison with 

the NAAQS. (See 40 CFR part 51, 

Appendix W, section 7.2.1.2, 40 CFR 

part 50, Appendix I, section 2.1.1, and 

Guidance on the Use of Models and 

Other Analyses for Demonstrating 

Attainment of Air Quality Goals for 

Ozone, PM2.5, and Regional Haze, EPA– 

454/B–07–002, April 2007.) The last set 

of DVFs (columns 6 and 7) are displayed 

to the nearest .0001 of a ppm. Although 

not relevant to determining attainment 

of the NAAQS, Colorado included these 

last columns as part of its evaluation of 

model performance, to attempt to 

distinguish any differences in the ozone 

projections between the 2010 base case 

and final 2010 control measure 

modeling and as part of its weight of 

evidence analysis. 

The maximum projected 8-hour ozone 

design value for the 2010 base case and 

final 2010 control measure case is 0.084 

ppm at the Rocky Flats North and Fort 

Collins West monitoring sites. Because 

all projected 2010 8-hour ozone design 

values are below 0.085 ppm, the 2010 

base case and final 2010 control 

measure case both pass the modeled 

ozone attainment demonstration test. 

However, because there are four 

monitoring sites with projected 2010 

DVFs of 0.082 ppm or higher (0.084 

ppm at Rocky Flats North and Fort 

Collins West, 0.083 ppm at Chatfield, 

and 0.082 ppm at NREL), EPA’s 

modeling guidance indicates a ‘‘weight 

of evidence’’ (WOE) analysis should be 

performed. 


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2Some urban areas show higher ozone levels on 

weekends. Some studies indicate that this increase 

in ozone concentrations may result from decreased 

weekend NOX emissions due to fewer trucks on the 

road and differences in the distribution of 

emissions. Under certain conditions, NOX acts to 

reduce ozone concentrations. 

TABLE 2—PROJECTED 2010 8-HOUR OZONE DVFS FOR THE 2010 BASE CASE AND FINAL 2010 CONTROL MEASURE

CASE

Monitor name County 

DVC 

(2005–2007) 

(ppm) 

2010 DVF (EPA Guidance) 

(ppm) 

2010 DVF (nearest 0.0001 

ppm) 

Base case Final control 

measure case Base case Final control measure case 

Welby ......................................................... Adams .......... 0.070 0.070 0.070 0.0702 0.0702 

Highland .................................................... Arapahoe ..... 0.078 0.077 0.077 0.0773 0.0773 

S. Boulder Creek ....................................... Boulder ......... 0.081 0.080 0.080 0.0808 0.0807 

Denver-CAMP ........................................... Denver ......... 0.056 0.056 0.056 0.0560 0.0560 

Carriage ..................................................... Denver ......... 0.074 0.074 0.074 0.0741 0.0741 

Chatfield State Park .................................. Douglas ........ 0.084 0.083 0.083 0.0834 0.0834 

USAF Academy ......................................... El Paso ........ 0.073 0.072 0.072 0.0720 0.0720 

Manitou Springs ........................................ El Paso ........ 0.074 0.073 0.073 0.0737 0.0737 

Arvada ....................................................... Jefferson ...... 0.079 0.079 0.079 0.0792 0.0791 

Welch ......................................................... Jefferson ...... 0.075 0.075 0.075 0.0750 0.0750 

Rocky Flats North ...................................... Jefferson ...... 0.085 0.084 0.084 0.0849 0.0849 

NREL ......................................................... Jefferson ...... 0.082 0.082 0.082 0.0823 0.0822 

Fort Collins West—Note: DVC based on 

two years of measured data.

Larimer ......... 0.086 0.084 0.084 0.0849 0.0848 

Fort Collins ................................................ Larimer ......... 0.074 0.073 0.073 0.0730 0.0730 

Greeley Weld Tower .................................. Weld ............. 0.078 0.077 0.077 0.0777 0.0775 

Gunnison ................................................... Gunnison ...... 0.068 0.067 0.067 0.0678 0.0678 

Larimer ...................................................... Larimer ......... 0.076 0.075 0.075 0.0752 0.0752 

For values that Colorado reported to 

the nearest 0.0001 of a ppm, the 

maximum projected DVF for the 2010 

Base Case is 0.0849 ppm at both the 

Rocky Flats North and Fort Collins West 

monitoring sites (see Table 2). 

According to Colorado’s modeling, 

Colorado’s final 2010 control measures 

would reduce the DVF at the Fort 

Collins West monitoring site by 0.0001 

ppm (to 0.0848 ppm) and would have 

no effect at the Rocky Flats North 

monitoring site (0.0849 ppm). Overall, 

Colorado’s modeling projected that 

Colorado’s final 2010 control measures 

would reduce the 2010 DVF by 0.0001 

ppm at four sites and by 0.0002 ppm at 

one site, with the remainder of the 

monitoring sites having identical DVFs 

for the 2010 base case and final 2010 

control measure case. The largest ozone 

reduction due to Colorado’s final 2010 

control measures (0.0002 ppm) was 

projected to occur at the Weld County 

Tower monitoring site (Greeley), which 

is expected given the proximity of the 

monitor to the oil and gas developments 

in Weld County. Weld County is where 

the largest VOC emission reductions 

would occur due to Colorado’s final 

2010 control measures for condensate 

storage tanks. These results are 

consistent with Colorado’s 2010 

sensitivity modeling, which found that 

proposed oil and gas emission controls 

would have a bigger impact on ozone 

concentrations at Fort Collins West than 

Rocky Flats North. 

Based on our analysis, we are 

proposing approval of Colorado’s 

modeled attainment demonstration. 

Both the 2010 base case modeling and 

the final 2010 control measure case 

modeling show that the DMA/NFR area 

will attain the 8-hour ozone NAAQS by 

2010. However, because we are 

proposing to disapprove Colorado’s 

revisions to Regulation Number 7, 

Section XII, which Colorado relied on in 

its final 2010 control measure modeling, 

our proposed approval of Colorado’s 

attainment demonstration is based on 

the 2010 base case modeling. 

Because Colorado’s modeling 

demonstrates attainment in 2010 based 

on existing SIP-approved measures, and 

it is now 2010, such SIP-approved 

measures represent all measures 

necessary to demonstrate attainment as 

expeditiously as practicable as per 

section 172 of the CAA. Additional 

control measures would not advance the 

attainment date. 

F. Weight of Evidence 

As noted above, since four monitors 

(Rocky Flats North, Fort Collins West, 

Chatfield, and NREL) modeled 

concentrations that fall into the range of 

0.082 to 0.087 ppm, a weight of 

evidence (WOE) analysis is 

recommended by EPA (see ‘‘Guidance 

on the Use of Models and Other 

Analyses for Demonstrating Attainment 

of Air Quality Goals for Ozone, PM2.5, 

and Regional Haze,’’ EPA–454/B–07– 

002, April 2007). A WOE analysis 

involves one or more supplemental 

analyses to enhance the assessment of 

whether the planned emissions 

reductions will result in attainment of 

the 1997 0.08 ppm 8-hour ozone 

NAAQS. The WOE analysis includes: 

Monitoring and emission inventory 

trend analysis; review of the conceptual 

model for ozone formation along the 

North Front Range; additional modeling 

metrics; alternative attainment test 

methods; and assessment of the efficacy 

of Colorado’s SIP-approved regulations, 

state-only regulations, and voluntary 

control measures. The WOE analysis is 

then used to determine if the four 

monitors that modeled ozone 

concentrations in the range of 0.082 to 

0.087 ppm are expected to demonstrate 

attainment of the NAAQS. 

Our review of the WOE analysis 

identified a number of key points that 

provide further evidence that the 

modeling is reliable and that the DMA/ 

NFR area will attain the NAAQS. First, 

although individual concentrations have 

been highly variable, the aggregate trend 

in weather-corrected 4th maximum time 

series suggests ozone levels have been 

flat from 2004 through 2008. The WOE 

analysis suggests that ozone levels are 

not trending upward in the DMA/NFR 

and that the modeling conclusions are 

reasonable. Second, the WOE analysis of 

the weekend-weekday effect 2 related to 

potential disbenefits from NOX

reductions shows a stronger effect in the 

DMA and a weaker effect in outlying 

areas. This spatial pattern is consistent 

with the localized NOX disbenefit 

predicted by the photochemical grid 

modeling; thus, this aspect of the WOE 


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analysis supports the validity of the 

modeling. Third, within the DMA, 

potential increases in ozone 

concentrations due to NOX emissions 

reductions from the federal motor 

vehicle control program do not appear 

significant and should not threaten the 

NAAQS. At monitoring locations 

outside the DMA, the WOE analysis 

suggests that reductions in NOX

emissions will reduce ozone, possibly 

with greater efficiency than VOC 

reductions. Fourth, the WOE analysis 

includes other modeled metrics that 

indicate reductions by 2010 in total 

ozone, grid cells over 0.080 and 0.085 

ppm 8-hour ozone, and grid cell-hours 

over 0.080 and 0.085 ppm ozone based 

on the various control scenarios. For 

example, these metrics indicate a 

reduction in total ozone and grid cells 

greater than 0.085 ppm between the 

2006 and 2010 base cases of 21% and 

14%, respectively. This suggests that the 

changes in emissions between the 2006 

and 2010 base cases will reduce or have 

reduced ozone concentrations. 

EPA finds the WOE analysis provides 

further support to the photochemical 

grid modeling, and the modeling and 

WOE support a determination that the 

area will attain the 1997 0.08 ppm 

8-hour ozone NAAQS by 2010. 

G. Specific OAP Language 

We are proposing to disapprove the 

last paragraph on page IV–1 and the first 

paragraph on page IV–2 of the OAP 

because these paragraphs indicate that 

the OAP revises Section XII of 

Regulation Number 7 as part of the SIP. 

We are proposing to disapprove revised 

Section XII of Regulation Number 7, and 

approval of this language in the OAP 

would potentially conflict with our 

proposed disapproval of revised Section 

XII. We are proposing to disapprove the 

words ‘‘federally enforceable’’ in the 

second to last paragraph on page V–6 of 

the OAP for the same reason. The 

language in question reads, ‘‘AQCC 

action on December 12, 2008 adopted a 

federally enforceable SIP control 

measure revising Regulation No. 7 

*** ’’ Only our approval can make the 

revisions federally enforceable. 

Elsewhere, the OAP discusses 

‘‘adopted SIP control measures’’ or 

provisions that will be part of the SIP. 

We interpret these various references as 

reflecting the AQCC’s intent to submit 

the referenced regulations to us for 

approval and not as an indication that 

they are already part of the federally 

approved SIP or that our approval of the 

OAP alone will make the referenced 

regulations part of the federally 

approved SIP. We are acting on the 

referenced regulations as separate 

elements. 

We are also proposing to disapprove 

the reference to Attachment A in the 

OAP’s Table of Contents and on page 

IV–3 of the OAP because Attachment A 

was not submitted to us with the OAP 

and because the revisions referenced as 

being included in that Attachment A 

(revisions to Regulation Number 7, 

Regulation Number 3, and the Ambient 

Standards Regulation) were submitted 

to us separately for our action. As noted, 

we are acting on the revisions to those 

regulations as separate elements in this 

action. 

H. SIP Control Measures 

Colorado Regulation Number 3 

Colorado submitted revisions to 

Regulation Number 3, Parts A, B, and C, 

along with the OAP. Among other 

things, Part A requires stationary 

sources to submit Air Pollutant 

Emission Notices (APENs) to Colorado 

before emitting pollutants. A source’s 

APEN must include information about 

location and nature of the source and 

expected emissions. Part A also contains 

various exemptions from APEN filing. 

Colorado’s proposed revisions to Part A 

would remove several of these 

exemptions from the regulation. This 

would subject the specified source 

categories to APEN filing and potential 

regulation under Regulation Number 7, 

which uses the APEN-filing threshold in 

Regulation Number 3, Part A, as the 

trigger for applicability of various 

requirements. 

Regulation Number 3, Part B, contains 

construction permit requirements for 

stationary sources. Part B also contains 

various exemptions from minor source 

construction permit requirements. Part 

B contains a generic exemption for 

sources that are not required to file an 

APEN. Colorado recognized that its 

proposed removal of the APEN-filing 

exemption for certain sources under 

Part A would also have the effect of 

subjecting those sources to minor source 

construction permit requirements under 

Part B. For four types of sources, 

Colorado determined that this would 

not be appropriate and adopted a 

revision to Part B that would continue 

to exempt these four types of sources 

from minor source construction 

permitting. The premise behind all the 

minor source construction permitting 

exemptions in Part B is that the 

emissions from the specified sources are 

deemed to have a negligible impact on 

air quality. 

Regulation Number 3, Part C, contains 

Colorado’s operating permit 

requirements. Colorado submitted 

proposed revisions to Part C that remove 

certain oil and gas activities from Part 

C’s insignificant activity exemption. 

For the reasons discussed below, we 

are proposing to approve Parts A and B. 

The proposed revisions to Regulation 

Number 3, Part A, eliminate provisions 

that exempt the following specific types 

of oil and gas-related emission points 

from the APEN requirements: Petroleum 

industry flares with emissions of less 

than 5 tons per year, specified crude oil 

truck loading equipment, oil and gas 

production wastewater, crude oil 

storage tanks, surface water storage 

impoundments for certain oil 

production wastewater, and condensate 

storage tanks where production through 

the tank amounts to less than 730 

barrels per year. The elimination of 

these exemptions means that the facility 

will need to file APENs with the State, 

which should allow Colorado to collect 

more accurate inventory information 

regarding emissions related to oil and 

gas operations. This would also subject 

the specified source categories to the 

condensate storage tank VOC control 

requirements of Regulation Number 7, 

Section XII, which uses the APEN-filing 

threshold in Regulation Number 3, Part 

A, as an applicability threshold. 

The proposed revisions to Regulation 

Number 3, Part B maintain an existing 

exemption from minor source 

construction permitting requirements 

for certain emission points. The 

emission points consist of certain 

petroleum industry flares with 

emissions less than 5 tons per year, 

crude oil truck loading equipment and 

condensate truck loading equipment, oil 

and gas production wastewater, and 

crude oil storage tanks. As noted above, 

under the current SIP-approved version 

of Regulation Number 3, Part B, any 

emission points exempt from filing 

APENs are also exempt from minor 

source construction permit 

requirements. See Regulation Number 3, 

Part B, Section III.D.1.a, as contained in 

the EPA-approved SIP at https://

yosemite.epa.gov/R8/R8Sips.nsf/e5e850

cc767bc8b3872573a9004cad73/75c2

d810353a706a87256b7b0066624d?Open

Document. Thus, approval of Colorado’s 

proposed revisions to Part B would not 

change the status quo with regard to 

construction permitting requirements 

for these emission points. 

The revisions to Parts A and B make 

the SIP more stringent by subjecting 

additional emission sources to reporting 

requirements. We are proposing to 

approve these revisions because they 

strengthen the SIP. 

Regarding Part B of Regulation 

Number 3, we note that there is a 

discrepancy between the numbering of 


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3Colorado previously submitted revisions to Part 

B that contain changes to the numbering of Part B 

provisions; we will be acting on those revisions 

separately. 

4When we describe changes as clerical in this 

proposed action, we are referring to changes like 

section renumbering, alphabetizing of definitions, 

minor grammatical and editorial revisions, and 

changes in capitalization. 

5 In March of 1996, Colorado adopted changes to 

Section II.D as a matter of State law and submitted 

the revisions to us for approval. The revisions were 

part of an effort by Colorado at that time to establish 

a de minimis exemption from Regulation Number 

7’s RACT requirements. EPA never approved 

Continued 

the submitted revisions and the EPAapproved SIP. Colorado added new 

Sections II.D.1.k, l, m, and n to Part B 

to specify the four types of emissions 

points that will continue to be exempt 

from minor source construction 

permitting requirements. However, in 

the current EPA-approved SIP, Section 

III.D.1 of Part B lists the types of 

emissions points that are exempt from 

minor source construction permitting 

requirements.3 These emissions points 

are listed in Sections III.D.1.a through j. 

For purposes of this action, we are 

interpreting Colorado’s proposed 

revisions to Part B, in the form of 

Sections II.D.1.k through n, as being an 

addition to Section III.D.1, and 

following immediately after Section 

III.D.1.j of Part B of the EPA-approved 

SIP. As part of our final rulemaking 

action, we will craft appropriate 

regulatory language to effectuate our 

interpretation. 

EPA is proposing to disapprove 

Colorado’s proposed revisions to 

Regulation Number 3, Part C. As noted 

above, Regulation Number 3, Part C, 

contains Colorado’s operating permit 

regulations, which we do not approve 

into the SIP. Instead, we approve 

operating permit regulations under our 

operating permit regulations at 40 CFR 

part 70. Thus, we intend to consider 

approval of Colorado’s proposed Part C 

revisions pursuant to our part 70 

regulations at such time as Colorado 

submits an appropriate request under 40 

CFR 70.4(i). The revisions are 

meaningless absent their regulatory 

context, and that regulatory context is 

not part of the EPA-approved SIP and is 

not incorporated by reference into 40 

CFR part 52. Instead, the approval status 

of Colorado’s part 70 program is 

reflected in 40 CFR part 70, Appendix 

A. Thus, because we are obligated to act 

on the State’s SIP submission, we plan 

to disapprove these revisions as a 

revision to the SIP. If the State requests 

to withdraw Part C from the SIP revision 

prior to the time we take final action, we 

would not be obligated to take final 

action because Part C would no longer 

be pending before the Agency as a SIP 

revision. Additionally, if requested by 

the State, we will separately consider 

these revisions as a revision to the 

approved operating permit program for 

the State. 

Colorado Regulation Number 7 

Regulation Number 7 contains various 

requirements intended to reduce 

emissions of ozone precursors. These 

are in the form of specific emission 

limits applicable to various industries 

and generic Reasonably Available 

Control Technology (RACT) 

requirements. EPA approved the repeal 

and re-promulgation of Regulation 

Number 7 in 1981 (46 FR 16687, March 

13, 1981) and has approved various 

revisions to parts of Regulation Number 

7 over the years. Most recently, in 2008 

EPA approved revisions to the control 

requirements for condensate storage 

tanks in Section XII (73 FR 8194, 

February 13, 2008). 

Colorado submitted proposed 

revisions to Regulation Number 7 along 

with the OAP. On November 18, 2009, 

Colorado corrected the version of 

Regulation Number 7 it had submitted 

to reposition the words ‘‘State Only’’ in 

various sections of Regulation Number 

7. 

Colorado made substantive revisions 

to certain limited parts of Regulation 

Number 7, particularly Section XII, and 

also made non-substantive revisions to 

numerous parts of the regulation. For 

ease of consideration, Colorado 

submitted the full text of Regulation 

Number 7 as a SIP revision for our 

approval (with the exception of 

provisions designated ‘‘State Only’’). We 

are only seeking comment on Colorado’s 

proposed changes to the SIP-approved 

version of Regulation Number 7, which 

are described below; we do not view 

this rulemaking as re-opening our past 

approval of the portions of the 

regulation that were not substantively 

modified by the State as part of this 

submission. 

As noted above, Colorado designated 

various parts of Regulation Number 7 

‘‘State Only’’ and in Section I.A.1.c 

indicated that sections designated ‘‘State 

Only’’ are not federally enforceable. Our 

interpretation is that provisions 

designated ‘‘State Only’’ have not been 

submitted to us for approval since one 

of the key purposes of a SIP approval is 

to make the submitted regulations 

federally enforceable. Instead, we 

interpret these provisions to have been 

submitted for informational purposes. 

Hence, we are not proposing to act on 

the portions of Regulation Number 7 

designated ‘‘State Only’’ and do not 

discuss them further unless they impact 

the portions of the regulation that 

Colorado intended to be federally 

enforceable. 

Analysis of Regulation Number 7 

Changes by Section 

Section I: 

Section I contains applicability 

provisions, definitions of new and 

existing sources, and related provisions. 

Except for minor clerical changes,4 this 

section remains unchanged from the 

current SIP-approved version. Thus, we 

are proposing to approve the changes to 

conform the SIP to Colorado’s 

regulation. 

Section II: 

Section II contains general provisions. 

Section II.A contains definitions. The 

State alphabetized the definitions 

Otherwise, the definitions are 

unchanged. The State made minor 

clerical changes to Section II.B, which 

contains an exemption for emissions of 

organic compounds having negligible 

photochemical reactivity. The State 

made minor clerical changes to Section 

II.C, which contains generic RACT 

requirements. 

Section II as submitted reflects 

Colorado’s repeal of Sections II.E and F. 

Colorado had previously submitted 

Sections II.E and F to us for approval, 

but we never acted on them. Section II.E 

would have allowed Colorado to 

approve alternative emission control 

plans, compliance methods, test 

methods, and test procedures without 

EPA approval of a source-specific SIP 

revision. However, subsequent to 

submitting Section II.E to us, Colorado 

repealed it (in November 2003). Section 

II.F would have allowed Gates Rubber 

Company to satisfy VOC RACT 

requirements in Regulation Number 7 

related to surface coating operations by 

obtaining emission reduction credits 

from Coors Brewing Company. Gates 

Rubber Company stopped operating a 

few years ago, and Colorado repealed 

Section II.F as part of its December 12, 

2008 rulemaking. 

We are proposing to approve the 

changes to Sections II.A, B, and C as 

minor, non-substantive revisions. 

Because section II.E and F were never 

approved as part of the SIP, the State 

repeal of those provisions has no 

meaning for this action. However, we 

are proposing to approve the language of 

Regulation Number 7 that reflects the 

repeal of II.E and F to conform the SIP 

to the numbering of Colorado’s 

regulation. 

In addition to the changes noted 

above, the submitted revision to Section 

II reflects Colorado’s repeal of Section 

II.D.5 The SIP-approved version of 


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Colorado’s 1996 changes to Section II.D. Based on 

EPA’s indication that it intended to disapprove 

Colorado’s 1996 changes to Section II.D, Colorado 

repealed Section II.D entirely in November 2003. 

Colorado did not re-adopt the pre-1996 version of 

Section II.D, and the version of Regulation Number 

7 that we are considering in this action indicates 

that Section II.D has been repealed. 

Section II.D requires sources to seek a 

revision to the SIP to gain approval of 

alternative control plans and test 

methods and indicates that no 

alternative is effective until the 

alternative is approved as a revision to 

the SIP. Colorado originally adopted 

Section II.D in September 1989 to 

address specific EPA concerns that 

Colorado’s RACT rule would allow 

changes to control requirements or test 

methods without EPA approval. 

We are proposing to disapprove the 

repeal of Section II.D for the following 

reasons: (1) A court might interpret the 

repeal to allow the State to approve 

alternative control requirements and test 

methods without EPA approval, and 

without public involvement, which 

could undermine the enforceability of 

Regulation Number 7’s RACT 

requirements and would be inconsistent 

with the CAA, particularly section 

110(i); (2) the State has offered no 

explanation or justification for the 

repeal; and (3) other sections of 

Regulation Number 7 still crossreference Section II.D as specifying 

necessary procedures for gaining 

approval of alternative control 

requirements and test methods (See, 

e.g., Section IX.A.5.c of Regulation 

Number 7), and, therefore, removing 

Section II.D would introduce ambiguity 

into the Regulation. 

Our proposed disapproval of the 

repeal of Section II.D does not 

undermine the validity of the 

attainment demonstration. Rather, it 

strengthens it by ensuring that EPA and 

public review will be required before a 

source may use an alternative control 

requirement or test method. Such 

review will help ensure that any such 

alternative would not interfere with the 

effectiveness of the program as relied on 

for purposes of demonstrating 

attainment. Although we are proposing 

to disapprove the repeal of Section II.D, 

our disapproval would not trigger 

sanctions or a FIP obligation. This is 

because the repeal of Section II.D is not 

required by the CAA (see CAA section 

179), and our disapproval of the repeal 

of Section II.D would not leave a 

deficiency in the SIP. Section II.D will 

remain in the SIP after disapproval of 

Colorado’s proposed repeal, and it will 

be incumbent on sources and the State 

to comply with Section II.D’s 

requirements. Thus, there would be 

nothing for the State to correct through 

a SIP revision and nothing for us to 

correct through a FIP. 

Sections III through XI: 

The changes are clerical in nature and 

do not affect the substance of the 

requirements. Therefore, we are 

proposing to approve the changes. 

Section XII: 

Section XII contains the emission 

control requirements for condensate 

storage tanks. The State reorganized 

Section XII and included additional 

control requirements for condensate 

tanks. The following table outlines the 

reorganization/renumbering contained 

in Colorado’s proposed revisions to 

Section XII: 

Colorado revised section XII section 

number 

Corresponding EPA-approved section 

XII section number Subject 

XII.A ..................................................... XII.A ..................................................... Applicability. 

XII.A.1 .................................................. XII.A.1 .................................................. Applicability. 

XII.A.1.a through c ............................... XII.A.1.a through c ............................... Applicability. 

XII.A.1.d ............................................... None .................................................... Applicability. 

XII.A.2 .................................................. XII.D.4 .................................................. Exception to applicability for oil refineries. 

XII.A.3 .................................................. None .................................................... Applicability for natural gas processing plants and certain natural gas compressor stations. Indicates they are subject to 

Section XII.G. 

XII.A.4 .................................................. None .................................................... Applicability for certain glycol natural gas dehydrators, natural 

gas compressor stations, drip stations, or gas processing 

plants. Indicates they are only subject to XII.B and XII.H. 

XII.A.5 .................................................. XII.A.8 .................................................. Exception to applicability based on uncontrolled actual VOC 

emissions threshold of 30 tons per year. 

XII.B.1, 2, 3, 9, 12, and 14 .................. XII.D.1; XII.D.5 through 9 .................... Definitions of various terms. 

XII.B.4, 5, 6, 7, 8, 10, 11, and 13 ........ None .................................................... Definitions of various terms. XII.B.13 contains a State-only 

definition. 

XII.C.1.a ............................................... XII.D.2.a ............................................... General requirements for operation/maintenance of control 

equipment. 

XII.C.1.b ............................................... XII.D.2.b ............................................... General requirement to minimize leakage VOCs. 

XII.C.1.c ............................................... XII.A.7 and XII.A.4.h ............................ Air pollution control equipment control efficiency. Failure to operate and maintain control equipment at indicated locations 

is a violation. 

XII.C.1.d ............................................... XII.D.2.c ............................................... Requirements for combustion devices. 

XII.C.1.e and f ...................................... None .................................................... State-only requirements related to combustion devices. 

XII.C.2 and XII.C.2.a ............................ XII.D.3 .................................................. Emission factors for emission estimates. 

XII.C.2.b ............................................... None .................................................... State-only. Emission factors for emission estimates in areas 

other than the 8-hour ozone control area (DMA/NFR nonattainment area). 

XII.D ..................................................... XII.A.2 .................................................. Emission control requirements for condensate tanks. 

XII.D.1 .................................................. None .................................................... Control requirement for new and modified condensate tanks. 

XII.D.2.a(i) through (x) ......................... XII.A.2.a through h ............................... System-wide control requirements for condensate storage 

tanks. 

XII.D.2.b ............................................... XII.A.9 .................................................. Alternative emission control equipment. 

XII.E ..................................................... XII.A.3 .................................................. Monitoring. 

XII.E.1 .................................................. None .................................................... Requirements for control equipment other than a combustion 

device. 

XII.E.2 .................................................. None .................................................... State only requirement related to new and modified tanks controlled by a combustion device. 


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Colorado revised section XII section 

number 

Corresponding EPA-approved section 

XII section number Subject 

XII.E.3., XII.E.3.a and b ....................... XII.A.3.a and b ..................................... Checks for combustion devices. 

XII.E.4 .................................................. XII.A.4.j ................................................ Documentation of inspections. 

XII.E.4.a–d ........................................... XII.A.3.c–f ............................................ Requirements for the weekly check. 

XII.E.5 .................................................. None .................................................... State-only requirements for surveillance systems. 

XII.F ...................................................... XII.A.4 and XII.A.5 ............................... Recordkeeping and reporting requirements. 

XII.F.1 and 2 ........................................ XII.A.10 and 11 .................................... Marking of AIRS numbers on tanks. 

XII.F.3 ................................................... XII.A.4 .................................................. Introductory language for recordkeeping. 

XII.F.3.a(i) ............................................ XII.A.4.a ............................................... List of tanks and production volumes. 

XII.F.3.a(ii) and (iii) ............................... XII.A.4.b and c ..................................... Listing of emission factors and location and control efficiencies. 

XII.F.3.a(iv) ........................................... XII.A.4.d.i ............................................. List weekly and monthly production values. Describes how to 

determine the averages. 

XII.F.3.a(v)–(vii) .................................... XII.A.4.d.ii–iv ........................................ List weekly and monthly uncontrolled actual and controlled actual emissions by tank and system-wide. List percent reductions weekly and monthly. 

XII.F.3.a(viii) ......................................... XII.A.4.e ............................................... Note any downtime and account for it. 

XII.F.3.a(ix)–(x) .................................... XII.A.4.f–g ............................................ Maintaining and mailing of spreadsheet. 

XII.F.3.b–d ............................................ XII.A.4.h–j ............................................ Failure to have control equipment as indicated on spread 

sheet is violation. Retain spread sheets for five years. Maintain records of inspections. 

XII.F.3.e ................................................ None .................................................... State only. Maintain records of required surveillance system. 

XII.F.3.f ................................................. None .................................................... State only. Keep records for new and modified tanks—when 

installed, etc. 

XII.F.4 ................................................... XII.A.5 .................................................. Reporting for system-wide requirements. 

XII.F.4.a ................................................ XII.A.5.a ............................................... List tanks and production volumes. 

XII.F.4.b–c ............................................ XII.A.5.b–c ........................................... List emission factor and location and control efficiency. 

XII.F.4.d ................................................ XII.A.5.d ............................................... What different reports must show based on time of year. 

Emissions individual tanks. 

XII.F.4.e ................................................ XII.A.5.e ............................................... What different reports must show based on time of year. 

Emissions system-wide. 

XII.F.4.f ................................................. XII.A.5.f ................................................ What different reports must show based on time of year. Percent reduction system-wide. 

XII.F.4.g ................................................ XII.A.5.g ............................................... Note shutdown of control equipment and account for same in 

totals. 

XII.F.4.h ................................................ XII.A.5.h ............................................... State whether required reductions were achieved. 

XII.F.4.i ................................................. XII.A.5.i ................................................ Include any information requested by the Division. 

XII.F.4.j ................................................. XII.A.5.j ................................................ Retention period. 

XII.F.4.k ................................................ XII.A.5.k ............................................... Additional reporting, monthly reporting of problems and corrective actions. 

XII.F.4.l ................................................. XII.A.5.l ................................................ Identify before ozone season tanks being controlled to meet 

system-wide control requirements. 

XII.F.4.m–n ........................................... None .................................................... State-only additional requirements for certifications. 

XII.F.5 ................................................... XII.A.6 .................................................. Exemption from record-keeping and reporting requirements for 

natural gas compressor stations and drip stations authorized 

to operate pursuant to a construction or operating permit. 

XII.G ..................................................... XII.B ..................................................... Requirements for gas processing plants. Introductory statement. 

XII.G.1 .................................................. XII.B.1 .................................................. Part 60 leak detection applies. 

XII.G.2 .................................................. XII.B.2 .................................................. Applicability of control equipment. 

XII.G.3 .................................................. XII.B.3 .................................................. Compliance date for existing plants. 

XII.G.4 .................................................. XII.B.4 .................................................. Compliance date for new plants. 

XII.G.5 .................................................. None .................................................... New exemption for natural gas compressor stations and drip 

stations if certain conditions are met. 

XII.G.6 .................................................. None .................................................... Says that natural gas compressor station or natural gas drip 

station that has a glycol natural gas dehydrator and/or natural gas-fired stationary or portable engine is subject to Section XII.H and/or XVI. 

XII.H ..................................................... XII.C ..................................................... Requirements that apply to vents from gas-condensate-glycol 

separators on glycol natural gas dehydrators at an oil and 

gas exploration and production operation, natural gas compressor station, drip station or gas-processing plant. 

The main feature of Section XII 

remains the requirement for systemwide reductions in condensate storage 

tank VOC emissions. The current EPAapproved Section XII requires that 

uncontrolled actual condensate tank 

VOC emissions in the DMA/NFR area be 

reduced on a weekly basis during the 

summer ozone season by 75% systemwide beginning May 1, 2007, and 78% 

beginning May 1, 2012. Revised Section 

XII (Section XII.D.2) requires an 81% 

system-wide reduction in uncontrolled 

actual weekly condensate tank VOC 

emissions during the summer ozone 

season beginning May 1, 2009, an 85% 

reduction beginning May 1, 2010, and a 

90% reduction beginning May 1, 2011. 

Also, most of the definitions and 

monitoring, recordkeeping, and 

reporting requirements in Section XII 

are unchanged. However, because of 

deficiencies in Colorado’s proposed 

revisions to Section XII, we cannot 


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6We note that the system-wide weekly reduction 

requirement of 78% that commences in May 2012 

in the current EPA-approved version of Section XII 

contains no termination date. 

approve revised Section XII. Below, we 

describe in detail Colorado’s proposed 

revisions to Section XII and the basis for 

our proposed disapproval of such 

revisions. 

As noted above, Colorado was able to 

demonstrate attainment using the 2010 

base case inventory. This inventory 

assumed the continuation of Section XII 

requirements as contained in the current 

EPA-approved SIP, and no new SIP 

control measures. Thus, disapproval of 

Colorado’s proposed Section XII 

revisions would not invalidate the 

attainment demonstration and, thus, 

would not trigger sanctions or a FIP 

obligation. 

Analysis of Specific Section XII 

Revisions 

Section XII.A. 

Section XII.A defines the applicability 

of Section XII requirements and is 

consistent with the current EPAapproved applicability provisions in 

Section XII. 

Section XII.B. 

Section XII.B contains definitions 

specific to Section XII. The substance of 

the definitions contained in Sections 

XII.B.1, 2, 3, 9, 12, and 14 is unchanged 

from the definitions contained in SIPapproved Sections XII.D.1 and XII.D.5 

through 9. The other definitions in 

revised Section XII.B define the 

following terms that are used in Section 

XII: auto-igniter, calendar week, 

condensate storage tank, downtime, 

existing, modified or modification, and 

new. The definitions are clear, 

straightforward, and accurate. The 

definitions of auto-igniter and existing 

are only pertinent to State-only 

provisions and thus have no meaning 

for our SIP action. 

Section XII.C.1. 

Section XII.C.1 contains general 

requirements for air pollution control 

equipment and prevention of leakage. 

Colorado did not change the substance 

of the corresponding EPA-approved 

provisions. 

Section XII.C.2. 

Section XII.C.2 describes the emission 

factors to be used for estimating 

emissions and emissions reductions 

from condensate storage tanks under 

Section XII. Colorado made one change 

to the substance of the corresponding 

EPA-approved provisions: In the current 

EPA-approved SIP (Sections XII.D.3.b 

and 3.b.i), the emission factors to be 

used are specified for condensate 

storage tanks at natural gas compressor 

stations, natural gas drip stations, and 

gas-condensate-glycol separators. In 

revised Sections XII.C.2.a.(ii) and 

a.(ii)(A), Colorado deleted the reference 

to gas-condensate-glycol separators. 

Revised Section XII.H still requires a 90 

percent reduction in emissions at 

certain gas-condensate-glycol 

separators, and Colorado has not 

explained why an emission factor 

specified or determined under Section 

XII.C.2 will not be needed to determine 

compliance with Section XII.H. We 

believe an emission factor will be 

needed to ensure that the reduction 

requirement in Section XII.H can be 

enforced. Thus, this is a deficiency in 

revised Section XII that forms part of the 

basis for our proposed disapproval of 

Section XII.D. 

Section XII.D contains an 

introductory statement regarding the 

control requirements for atmospheric 

condensate storage tanks. The changes 

to current SIP-approved Section XII.A.2 

are minor. While the statement that 

‘‘[e]mission reductions shall not be 

required for each and every unit’’ is 

misleading because the control 

requirement in revised Section XII.D.1 

for new and modified condensate tanks 

applies to every tank, this misstatement 

would not undermine the enforceability 

of the requirements in Section XII.D.1. 

However, Colorado should correct this 

statement. 

Section XII.D.1. 

Section XII.D.1 requires owners or 

operators of any new or modified 

condensate tank at exploration and 

production sites to route emissions to 

air pollution control equipment that has 

a control efficiency of at least 95% for 

VOCs. This requirement applies for the 

first 90 days after the date of first 

production or after a well is newly 

drilled, re-completed, re-fractured, or 

otherwise stimulated. After the initial 

90 days, the emission controls required 

by this subsection may be removed 

provided the source can demonstrate 

compliance with the system-wide 

provisions specified in other 

subsections of section XII. This new 

requirement would strengthen the SIP. 

Section XII.D.2.a. 

Section XII.D.2.a contains the systemwide control requirements for 

condensate storage tanks. The current 

SIP provides for a weekly 75% systemwide VOC reduction during the summer 

ozone season beginning in 2010. As 

noted above, the revised section 

significantly increases the summer 

ozone season weekly VOC reduction 

requirements from the current EPAapproved requirements, to 85% 

beginning in 2010 and 90% beginning 

in 2011. However, the revised 

provisions specify no system-wide 

weekly VOC reduction requirement after 

the 2012 summer ozone season.6

As noted previously, Colorado was 

able to demonstrate attainment based on 

a 75% system-wide weekly VOC 

reduction from condensate storage tanks 

beginning in 2010. While revised 

Section XII would provide more 

stringent reductions in the short term, 

including the attainment year, it 

contains no weekly emission reduction 

requirement after the 2012 summer 

ozone season. Thus, although it is more 

stringent in the short term, it is less 

stringent over the long term, and the 

State has not demonstrated how this 

weakening of the SIP will not interfere 

with maintenance of the NAAQS. This 

deficiency forms part of the basis for our 

proposed disapproval of revised Section 

XII. 

Section XII.D.2.b. 

Section XII.D.2.b is a re-numbered 

version of current EPA-approved 

Section XII.A.9. This section contains a 

process for approval of alternative 

emissions control equipment and 

pollution prevention devices and 

processes. Among other things, the 

section specifies requirements for public 

participation and EPA approval. 

Colorado did not change the substance 

of this provision, but simply 

renumbered it from Section XII.A.9 to 

now be section XII.D.2.b. 

The revised section contains 

typographical errors that Colorado 

should correct. In Section XII.D.2.b, 

Colorado should delete the word ‘‘this’’ 

in ‘‘this Section XII.D.2.a’’ because 

Section XII.D.2.a is not part of Section 

XII.D.2.b. In Section XII.D.2.b.(i)(E), the 

reference to ‘‘the spreadsheet and annual 

report required by Sections XII.F.4 and 

XII.F.5’’ should be to ‘‘the spreadsheet 

and annual report required by Sections 

XII.F.3 and XII.F.4.’’ 

Section XII.E. 

Section XII.E contains the monitoring 

requirements that are currently 

specified in EPA-approved Sections 

XII.A.3 and XII.A.4.j. Colorado retained 

the basic requirement for weekly 

inspections or monitoring. 

Colorado improved certain 

provisions. For example, under revised 

Section XII.E, an owner or operator 

must ensure that the control equipment 

is not only operating, but that it is 

operating properly. Revised Section 

XII.E.1 adds a requirement that owners 


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or operators of control equipment other 

than a combustion device follow 

manufacturer’s recommended 

maintenance and inspect the equipment 

to ensure proper maintenance and 

operation. Revised Section XII.E.4 

(current XII.A.4.j) adds a requirement 

that the owner or operator document 

any corrective actions taken and the 

name of the individual performing the 

corrective actions resulting from a 

weekly inspection. Revised Sections 

XII.E.4.a through d add the requirement 

that the owner or operator not only 

perform certain checks, but that the 

owner or operator document those 

checks. 

Revised Section XII.E.3 is deficient. It 

specifies certain inspection and/or 

monitoring requirements for combustion 

devices. It introduces two possible 

means to monitor/inspect the 

combustion device, but one of them— 

use of a surveillance system—is 

designated as a State Only option. The 

federally-enforceable SIP cannot 

provide a compliance option that is only 

available as a matter of State law. 

Discussions with the State have 

revealed that use of a surveillance 

system was not intended as an 

alternative to the monitoring method 

contained in Section XII.E.3.a, but as a 

technique that owners/operators could 

use on a trial basis in addition to the 

method contained in Section XII.E.3.a. 

Thus, the word ‘‘either’’ in Section 

XII.E.3 and the words ‘‘and/or’’ in 

XII.E.3.a are not appropriate. This 

deficiency forms part of the basis for our 

proposed disapproval of revised Section 

XII. 

Section XII.F. 

Section XII.F contains recordkeeping 

and reporting requirements that are 

currently specified in EPA-approved 

Sections XII.A.4 and XII.A.5. The 

recordkeeping requirements specify 

information that must be listed on a 

spreadsheet that owners/operators must 

maintain. Many of the provisions are 

identical to those in the current EPAapproved SIP. 

Sections XII.F.1 through 4. 

In Sections XII.F.1 through 4, 

Colorado made a few substantive 

changes to the existing provisions. In 

revised Section XII.F.3, Colorado added 

a sentence requiring the owner or 

operator to track VOC reductions on a 

calendar weekly and calendar monthly 

basis to demonstrate compliance with 

system-wide VOC reduction 

requirements. Colorado also specified 

that owners/operators would need to 

use the Division-approved spreadsheet 

to track VOC emissions and reductions, 

not just any spreadsheet. These changes 

are reasonable and consistent with CAA 

requirements. 

In revised Section XII.F.3.a(i), which 

requires the spreadsheet to list the 

condensate storage tanks subject to 

Section XII and the production volumes 

for each tank, Colorado specified that 

the spreadsheet must list monthly 

production volumes. It is unclear why 

Colorado added the word ‘‘monthly’’ 

because the following sentence, which 

Colorado did not change, requires the 

owner/operator to list the most recent 

measurement of such production and 

the time period covered by the 

measurement. Also, revised Section 

XII.F.3.a(iv) requires the owner/operator 

to list the production volume for each 

tank as a weekly and monthly average 

based on the most recent measurement 

available and specifies the method for 

pro-rating that measurement over the 

weekly or monthly period. Given the 

specificity of Section XII.F.3.a(iv), we 

are not concerned that the addition of 

the word ‘‘monthly’’ in revised Section 

XII.F.3.a(i) would undermine the 

enforceability of the regulation. 

However, Colorado should remove the 

word ‘‘monthly’’ in revised Section 

XII.F.3.a(i). 

Revised Section XII.F.3.c requires 

owners/operators to retain a copy of 

each weekly and monthly spreadsheet 

for five years instead of the three years 

required by current EPA-approved 

Section XII.A.4.i. 

Revised Section XII.F.3.d requires 

owners/operators to maintain records of 

inspections required by Section XII.E 

but does not specify a period for 

maintenance of the records. This is 

consistent with EPA-approved Section 

XII.A.4.j. However, we consider this 

something that Colorado should 

address. Typically, EPA recommends 

that such records be kept for a minimum 

of five years. 

Revised Section XII.F.3 does not 

contain adequate recordkeeping for the 

control requirement that applies to new 

and modified condensate tanks under 

Section XII.D.1. As noted above, for new 

and modified condensate tanks, owners 

or operators are required to use air 

pollution control equipment with a 

control efficiency of at least 95% for the 

first 90 days. However, the regulation 

only specifies State-only recordkeeping 

requirements relevant to this 

requirement—in Section XII.F.3.f—and 

includes no reporting requirements that 

would be federally enforceable. To meet 

CAA requirements, the regulation, at a 

minimum, should specify that owners/ 

operators provide notification and 

maintain certain records. We believe 

relevant records would include, but may 

not be limited to: The date a new 

atmospheric condensate storage tank 

was installed, or the date a well was 

newly drilled, re-completed, refractured or otherwise stimulated; the 

date the control equipment was 

installed and, if applicable, removed; 

the manufacturer’s design specifications 

for the control equipment; the 

manufacturer’s operation and 

maintenance specifications/instructions 

for the control equipment; and any 

downtime of the control equipment or 

other operational problems and 

corrective action taken. The regulation 

should also specify a record retention 

period for such records. The regulation 

specifies a five-year retention period for 

other records, and it would be 

appropriate to specify the same 

retention period for these records. The 

regulation should also specify that 

owners/operators need to report within 

a reasonable period of time after the 

date the new atmospheric condensate 

storage tank was installed or the date 

the well was newly drilled, recompleted, re-fractured or otherwise 

stimulated. The regulation should also 

require the owner/operator to report any 

non-compliance with the requirements 

of Section XII.D.1 within a reasonable 

time frame. The deficiencies in 

recordkeeping and reporting 

requirements pertaining to the control 

requirements of revised Section XII.D.1 

form part of the basis for our proposed 

disapproval of revised Section XII. 

In revised Section XII.F.4, Colorado 

made minor changes to current EPAapproved reporting requirements. 

Revised Section XII.F.4.a requires the 

semi-annual reports to list all 

condensate storage tanks subject to or 

used to comply with the system-wide 

reduction requirements, not just those 

subject to such requirements. This 

reflects the change to the regulation that 

allows owners/operators to control 

tanks with emissions below the APEN 

filing levels to meet the percent 

reduction requirement in Section 

XII.D.2. In revised Sections XII.F.4.d 

through f Colorado clarified that the 

April 30 reports must include the 

monthly emissions information and the 

November 30 reports must include the 

weekly emissions information. In 

revised Section XII.F.4.g, Colorado 

deleted the requirement in current EPAapproved Section XII.A.5.g that the 

owner/operator note in the report ‘‘the 

date the source believes the shutdown 

[of control equipment] occurred, 

including the basis for such belief.’’ We 

believe this deletion is reasonable 

because the owner/operator is not likely 

to be able to make an accurate estimate 


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of the date the shutdown occurred, and, 

thus, the information is not likely to be 

meaningful in an enforcement context. 

In revised Section XII.F.4.h, Colorado 

clarified monthly versus weekly 

reporting requirements. In revised 

Section XII.F.4.j, Colorado increased the 

retention period for reports from three 

years to five years. These changes are 

consistent with CAA requirements. 

Revised Section XII.F.4.l contains a 

reference to ‘‘this Section XII.D.2.’’ The 

word ‘‘this’’ should be deleted. This 

typographical error is not significant 

enough to undermine the enforceability 

of the regulation, but Colorado should 

correct it. 

Section XII.F.5. 

Section XII.F.5 contains an exemption 

from Section XII’s record-keeping and 

reporting requirements for owners/ 

operators of natural gas compressor 

stations (NGCSs) or natural gas drip 

stations (NGDSs) authorized to operate 

pursuant to a construction permit or 

Title V operating permit if certain 

conditions are met. Colorado removed 

one of the conditions for this exemption 

contained in current EPA-approved 

Section XII.A.6. The removed condition 

provided that total emissions from 

condensate storage tanks associated 

with such NGCSs and NGDSs could not 

exceed 30 tons per year. If we approve 

the deletion of this condition, the 

recordkeeping and reporting 

requirements for the relevant sources 

with emissions exceeding the 30 tons 

per year threshold would need to be 

established through construction or 

Title V operating permits. Our 

interpretation of the CAA is that 

provisions such as monitoring, 

recordkeeping, and reporting 

requirements that are needed to ensure 

the enforceability of the applicable 

control requirements contained in a SIP 

must also be contained in the SIP and 

cannot be left to development in a 

permit. See. e.g., CAA sections 

110(a)(2)(A) and (F), 40 CFR part 51, 

Subpart K, and 40 CFR part 51, 

Appendix V. This deficiency forms part 

of the basis for our proposed 

disapproval of revised Section XII. 

We approved the prior version of the 

exemption because Section XII’s systemwide VOC reduction requirements were 

limited to systems with emissions over 

30 tons per year. In other words, all 

owners/operators, including owners/ 

operators of NGCSs and NGDSs, were 

exempt from Section XII’s main 

requirements, including the 

recordkeeping and reporting 

requirements, if emissions from their 

units were under 30 tons per year. 

Revised Section XII.F.5 also contains 

typographical errors. In the first line, the 

reference to ‘‘Sections XII’’ should be to 

‘‘Section XII.’’ In XII.F.5.a, the reference 

to ‘‘this Section XII.A’’ should be to 

‘‘Section XII.D.’’ 

Section XII.G. 

Section XII.G specifies the control 

requirements applicable to gasprocessing plants and corresponds to 

current EPA-approved Section XII.B. 

EPA-approved Section XII.B requires 

gas-processing plants to meet the 

requirements in Section XII.B 

specifically applicable to such plants as 

well as the requirements in current 

EPA-approved Section XII.C, pertaining 

to certain still vents and vents from gascondensate-glycol separators, and 

Section XVI, pertaining to emissions 

from stationary and portable engines. 

Revised Section XII.G requires gasprocessing plants to additionally 

comply with the requirements of revised 

Section XII.B, the definitions section, 

and revised Sections XII.C.1.a and 

XII.C.1.b, which specify maintenance 

and design requirements for control 

equipment and the obligation to 

minimize leakage of VOCs to the 

atmosphere. It appears that this change 

would strengthen the requirements 

applicable to gas-processing plants. 

Section XII.G.1. 

Section XII.G.1 specifies that NSPS 

leak detection and repair requirements 

apply regardless of the date of 

construction of the facility. Colorado 

made no substantive changes to this 

provision. 

Section XII.G.2. 

Section XII.G.2 specifies the 

applicability threshold for installation 

of control equipment at gas-processing 

plants and the efficiency requirement 

for the control equipment. In current 

EPA-approved Section XII.B.2, 

installation of control equipment is 

triggered if condensate storage tank 

throughput exceeds ‘‘APEN de minimis 

levels.’’ In revised Section XII.G.2, 

installation is triggered if uncontrolled 

emissions from a tank or tank battery are 

greater than or equal to two tons per 

year. We cannot determine whether this 

change would strengthen the regulation, 

weaken it, or leave it the same because 

we cannot determine whether the same 

tanks or tank batteries would have to 

install control equipment or not. 

Colorado also revised the control 

efficiency requirement from 95%, with 

no averaging period specified, to 95% 

with a rolling 12-month averaging 

period. We are not convinced this 

change is consistent with CAA 

requirements. The revised regulation 

contains no provisions for testing or 

determining whether the 95% control 

has been achieved on a rolling 12-month 

basis, and if the goal is to have owners/ 

operators install and operate flares with 

a control efficiency of at least 95%, 

specifying an averaging period is not 

particularly meaningful. These issues 

form part of the basis for our proposed 

disapproval of revised Section XII. 

Section XII.G.3. 

Section XII.G.3 specifies the 

compliance date for existing natural gas 

processing plants. Colorado did not 

change the substance of this provision. 

Section XII.G.4. 

Revised Section XII.G.4, which 

specifies the compliance date for new 

gas processing plants, contains 

typographical errors. The reference to 

‘‘this Section XII.B’’ should be to ‘‘this 

Section XII.G.’’ The reference to Section 

XII.C should be to Section XII.H. 

Section XII.G.5. 

Section XII.G.5 is entirely new. It 

adds an exemption from the otherwise 

applicable requirements of Section XII 

for an owner or operator of any NGCS 

or NGDS, but only if the owner or 

operator applies control equipment 

designed to achieve a VOC control 

efficiency of at least 95% to each 

condensate storage tank or tank battery 

with uncontrolled VOC emissions 

greater than or equal to two tons per 

year and meets certain other 

requirements. While this is a more 

stringent requirement than the systemwide requirement because it requires 

95% control at each tank or tank battery 

over the threshold rather than a 

maximum of 90% control system-wide, 

Section XII does not specify 

recordkeeping and reporting 

requirements to support the provisions 

of revised Section XII.G.5. Adequate 

recordkeeping and reporting 

requirements in the SIP are necessary to 

ensure the enforceability of the control 

requirement and to meet CAA 

requirements. This deficiency forms 

part of the basis for our proposed 

disapproval of revised Section XII. 

Section XII.G.6. 

Section XII.G.6 is new. It specifies 

that a NGCS or NGDS subject to Section 

XII.G at which a glycol natural gas 

dehydrator or natural gas-fired 

stationary or portable engine is operated 

shall be subject to Section XII.H and/or 

XVI. We interpret this to mean that the 

provisions of Sections XII.H and XVI, as 

applicable, would apply to such 

facilities in addition to the provisions of 

Section XII.G. We view this as a 


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clarifying change that is consistent with 

CAA requirements. 

Section XII.H. 

Section XII.H specifies control 

requirements for still vents and vents 

from gas-condensate-glycol separators 

on glycol natural gas dehydrators 

located at oil and gas exploration and 

production operations, natural gas 

compressor stations, drip stations, or 

gas-processing plants. In revised Section 

XII.H, Colorado attempted to clarify 

current EPA-approved Section XII.C’s 

applicability threshold for control 

requirements. The relevant language in 

revised Section XII.H reads as follows: 

This Section XII.C shall not apply to any 

single natural gas dehydrator, or grouping of 

dehydrators at an oil and gas exploration and 

production operation, natural gas compressor 

station, drip station or gas-processing plant, 

with uncontrolled actual emissions of 

volatile organic compounds of less than 15 

tons per year. To determine if a grouping of 

dehydrators exceeds the 15 tons per year 

threshold aggregate emissions from all 

dehydrators on site (contiguous and 

adjacent). The control requirement in this 

Section XII.H. shall apply to each natural gas 

dehydrator within a grouping that has actual 

uncontrolled emissions above one ton per 

year. The control requirement in this Section 

XII.H. shall not apply to a natural gas 

dehydrator with emissions below the APEN 

reporting thresholds in Regulation Number 3, 

Part A, Section II.D that is part of a grouping 

of dehydrators, but the emissions from such 

dehydrator shall be included in the 

calculation. 

As written, this passage lacks clarity 

and contains redundant language that 

EPA cannot approve. While we think we 

understand the intent—that emissions 

from all dehydrators are counted in 

determining whether the 15-ton-peryear threshold is exceeded, but the 

control requirement only applies to 

dehydrators with actual uncontrolled 

emissions above one ton per year—the 

redundant language and lack of 

punctuation or missing words in the 

third sentence of revised Section XII.H 

create uncertainty. The same is true of 

stating the threshold for control in two 

different ways: Controls apply where 

emissions exceed one ton per year 

versus controls don’t apply where 

emissions are below the APEN reporting 

thresholds. This deficiency forms part of 

the basis for our proposed disapproval 

of revised Section XII. 

We also note that in the quoted 

passage above, the reference to ‘‘This 

section XII.C’’ should be to ‘‘This section 

XII.H’’ and that Colorado should correct 

this typographical error. 

Proposed Action on Section XII 

Revisions 

Based on the deficiencies noted 

above, we are proposing to disapprove 

the Section XII revisions. While several 

of the changes contained in revised 

Section XII would strengthen the SIP, 

we are unable to use our authority for 

partial or limited approval. First, under 

the circumstances involved here and 

based on our interpretation of the CAA, 

it is not appropriate to replace a fully 

approved Section XII in the SIP with a 

revised Section XII that contains 

deficiencies. Second, we have no means 

to approve only those provisions that 

strengthen the SIP and reject the rest 

because Colorado completely 

reorganized and renumbered Section 

XII’s provisions. The numbering of any 

relevant subsections that we could 

approve would not match the 

numbering of the current EPA-approved 

subsections; the resulting SIP rule 

would be unintelligible. Thus, we find 

that our only available course of action 

is to propose to disapprove all of revised 

Section XII. 

Sections XIII through XVI 

Sections XIII through XVI changes are 

clerical in nature and do not affect the 

substance of the requirements. 

Therefore, we are proposing to approve 

the changes in Sections XIII through 

XVI. 

Ambient Air Quality Standards 

Regulation 

We are proposing to disapprove 

Colorado’s proposed revisions to its 

ambient air quality standards regulation. 

Colorado’s ambient air quality standards 

regulation duplicates information 

contained in other parts of the SIP and 

in our regulations. For example, the 

ambient air quality standards regulation 

restates the motor vehicle emissions 

budgets for various areas. However, 

under our regulations, the budgets are 

determined by the applicable control 

strategy SIP or maintenance plan, not by 

Colorado’s ambient air quality standards 

regulation. Similarly, the ambient air 

quality standards regulation defines the 

boundaries and designations of various 

areas in Colorado. However, EPA 

defines the designations and boundaries 

of areas in its own regulations. Approval 

of the ambient air quality standards 

regulation could lead to confusion in 

the event of conflict between the 

ambient air quality standards regulation 

and our regulations or other parts of the 

SIP. 

Because we are obligated to act on the 

State’s SIP submission, we plan to 

disapprove these revisions to the 

ambient air quality standards regulation 

as a revision to the SIP. If the State 

requests to withdraw the regulation 

from the SIP revision prior to the time 

we take final action, we would not be 

obligated to take final action because the 

revisions to the ambient air quality 

standards regulation would no longer be 

pending before the Agency as a SIP 

revision. 

I. Transportation Conformity 

Under section 176(c) of the CAA, 

transportation plans, transportation 

improvement programs, and new 

transportation projects, such as the 

construction of new highways, must 

‘‘conform’’ to (i.e., be consistent with) 

applicable SIPs. Conformity to a SIP 

means that transportation activities will 

not produce new air quality violations, 

worsen existing violations, or delay 

timely attainment of the NAAQS. EPA’s 

conformity rule provisions in 40 CFR 

part 93 establish the criteria and 

procedures for determining whether or 

not these plans, programs, and projects 

conform to the SIP. In particular, our 

regulations require a demonstration that 

emissions from these plans, programs, 

and projects will be consistent with the 

motor vehicle emissions budgets 

(MVEBs) in the SIP (40 CFR 93.118). 

The MVEBs are defined as that portion 

of the total allowable emissions defined 

in the SIP for a certain date, for the 

purpose of meeting reasonable further 

progress milestones or demonstrating 

attainment or maintenance of the 

NAAQS, allocated to highway and 

transit vehicle use and emissions. 

EPA’s requirements on MVEBs are 

found in 40 CFR 93.118 and 93.124, and 

MVEBs are further explained in the 

preamble to the November 24, 1993, 

transportation conformity rule (58 FR 

62193–62196). Colorado derived the 

MVEBs for NOX and VOCs from its 2010 

base case attainment demonstration and 

defined the MVEBs in Chapter VI of the 

OAP. We list the MVEBs in Table 3, 

below. 


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TABLE 3—IDENTIFICATION OF 2010 NOX AND VOC MVEBS

Area of applicability 

2010 NOX

Emissions 

(tons per day) 

2010 VOC 

Emissions 

(tons per day) 

Northern Subarea ............................................................................................................................................ 20.5 19.5 

Southern Subarea ............................................................................................................................................ 102.4 89.7 

Total Nonattainment Area ........................................................................................................................ 122.9 109.2 

Once Colorado submitted the OAP to 

us, we determined the adequacy of the 

MVEBs per the procedures and criteria 

contained in 40 CFR 93.118. On October 

15, 2009, we announced the availability 

of the attainment demonstration and the 

MVEBs on EPA’s transportation 

conformity adequacy Web site and 

solicited public comment. The public 

comment period closed on November 

16, 2009; we received no comments. All 

of this information is available at EPA’s 

conformity Web site: http:// 

www.epa.gov/otaq/stateresources/

transconf/currsips.htm#denver-me. 

In a January 21, 2010 letter to the 

Colorado Department of Public Health 

and Environment, we found that the 

2010 NOX and VOC MVEBs in the OAP 

were adequate. We announced our 

adequacy finding in the Federal 

Register on March 4, 2010, and the 

OAP’s MVEBs became effective on 

March 19, 2010. As a result, as of that 

date, the Denver Regional Council of 

Governments (DRCOG), the North Front 

Range Transportation and Air Quality 

Planning Council (NFRT), the Colorado 

Department of Transportation, and the 

U.S. Department of Transportation were 

required to use these MVEBs for 

transportation conformity 

determinations. However, we note that 

we are not bound by our prior adequacy 

determination in this action. 

Our analysis indicates that the MVEBs 

are consistent with and clearly related 

to the emissions inventory and the 

control measures in the SIP, and that the 

MVEBs, when considered together with 

all other emissions sources, are 

consistent with attainment of the 1997 

8-hour ozone NAAQS in 2010. (See 40 

CFR 93.118(e)(4).) Therefore we are 

proposing approval of the MVEBs as 

reflected in Table 3 above. 

We note that our proposed approval 

applies to the Northern Subarea and 

Southern Subarea MVEBs as well as the 

Total Nonattainment Area MVEBs. The 

Northern Subarea is defined in the OAP 

as the area denoted by the ozone 

nonattainment area north of the Boulder 

County northern boundary and 

extended through southern Weld 

County to the Morgan County line. This 

area includes NFRT’s regional planning 

area as well as part of the Upper Front 

Range Transportation Planning Region 

(TPR) in Larimer and Weld counties. 

The Southern Subarea is defined in 

the OAP as the area denoted by the 

ozone nonattainment area south of the 

Boulder County northern boundary and 

extended through southern Weld 

County to the Morgan County line. This 

area includes the nonattainment portion 

of DRCOG’s regional planning area and 

the southern Weld County portion of the 

Upper Front Range TPR. We note that 

both subareas are further identified in 

Figure 2: ‘‘8-hour Ozone Emission 

Budget Subareas’’ at page VI–6 in the 

OAP. 

In addition to proposing approval of 

the MVEBs, we are also proposing to 

approve the process described in the 

OAP for use of the Total Nonattainment 

Area MVEBs and the subarea MVEBs. 

Per the OAP, the initial conformity 

determination must use the Total 

Nonattainment Area MVEBs for NOX

and VOCs. After the initial conformity 

determination, DRCOG and NFRT may 

switch from using the Total 

Nonattainment Area MVEBs to using the 

subarea MVEBs for determining 

conformity. To switch to use of the 

subarea MVEBs (or to subsequently 

switch back to use of the Total 

Nonattainment Area MVEBs,) DRCOG 

and the NFRT must use the process 

described in the OAP at pages VI–4 and 

VI–5. 

V. Consideration of Section 110(l) of the 

CAA 

Section 110(l) of the CAA states that 

a SIP revision cannot be approved if the 

revision would interfere with any 

applicable requirement concerning 

attainment and reasonable further 

progress towards attainment of a 

NAAQS or any other applicable 

requirement of the CAA. The parts of 

the OAP and the regulation revisions we 

are proposing to approve will not 

interfere with attainment, reasonable 

further progress, or any other applicable 

requirement of the CAA. The OAP 

contains a valid modeled attainment 

demonstration showing the area will 

attain by 2010. As described elsewhere 

in this action, we are proposing to 

disapprove Colorado’s proposed repeal 

of Section II.D of Regulation Number 7, 

Colorado’s revisions to Section XII of 

Regulation Number 7, Colorado’s 

revisions to Part C of Regulation 

Number 3, Colorado’s revisions to its 

Ambient Air Quality Standards 

regulation, and specific limited portions 

of the OAP because those provisions do 

not meet all applicable requirements of 

the CAA. 

VI. Proposed Action 

We are proposing to approve 

Colorado’s 2010 attainment 

demonstration for the 1997 8-hour 

ozone NAAQS. We are proposing to 

approve the motor vehicle emissions 

budgets contained in the OAP. We are 

proposing to approve all other aspects of 

the OAP, with the following limited 

exceptions: we are proposing to 

disapprove the last paragraph on page 

IV–1 and the first paragraph on page IV– 

2 of the OAP, we are proposing to 

disapprove the words ‘‘federally 

enforceable’’ in the second to last 

paragraph on page V–6 of the OAP, and 

we are proposing to disapprove the 

reference to Attachment A in the OAP’s 

Table of Contents and on page IV–3 of 

the OAP. 

We are proposing to approve the 

revisions to Colorado Regulation 

Number 3, Parts A and B. We are 

proposing to disapprove the revisions to 

Colorado Regulation Number 3, Part C. 

We are proposing to approve the 

following portions of the revisions to 

Colorado Regulation Number 7: 

• Revisions to Sections I through XI, 

except for Colorado’s repeal of Section 

II.D. 

• Revisions to Sections XIII through 

XVI. 

We are proposing to disapprove the 

following portions of the revisions to 

Colorado Regulation Number 7: 

• Colorado’s proposed repeal of 

Section II.D. 

• Revisions to Section XII. 

We are proposing to disapprove the 

revisions to Colorado’s Ambient Air 

Quality Standards Regulation. 

The provisions we are proposing to 

approve meet the requirements of the 

CAA and our regulations, including 40 

CFR 81.300(e)(3)(ii)(D). The provisions 


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we are proposing to disapprove are 

inconsistent with CAA requirements 

and our regulations. Our specific 

analyses and findings are discussed 

above in the body of this proposed 

rulemaking. 

EPA is soliciting public comments on 

its proposed rulemaking as discussed in 

this document. EPA will consider these 

comments before taking final action. 

Interested parties may participate in the 

Federal rulemaking process by 

submitting written comments to EPA as 

discussed in this action. 

VII. Statutory and Executive Order 

Reviews 

Under the CAA, the Administrator is 

required to approve a SIP submission 

that complies with the provisions of the 

Act and applicable Federal regulations 

(42 U.S.C. 7410(k), 40 CFR 52.02(a)). 

Thus, in reviewing SIP submissions, 

EPA’s role is to approve state choices, 

provided that they meet the criteria of 

the CAA. Accordingly, this proposed 

action merely approves some State law 

as meeting Federal requirements and 

disapproves other State law because it 

does not meet Federal requirements; 

this proposed action does not impose 

additional requirements beyond those 

imposed by State law. For that reason, 

this proposed action: 

• Is not a ‘‘significant regulatory 

action’’ subject to review by the Office 

of Management and Budget under 

Executive Order 12866 (58 FR 51735, 

October 4, 1993); 

• Does not impose an information 

collection burden under the provisions 

of the Paperwork Reduction Act (44 

U.S.C. 3501 et seq.); 

• Is certified as not having a 

significant economic impact on a 

substantial number of small entities 

under the Regulatory Flexibility Act (5 

U.S.C. 601 et seq.); 

• Does not contain any unfunded 

mandate or significantly or uniquely 

affect small governments, as described 

in the Unfunded Mandates Reform Act 

of 1995 (Pub. L. 104–4); 

• Does not have Federalism 

implications as specified in Executive 

Order 13132 (64 FR 43255, August 10, 

1999); 

• Is not an economically significant 

regulatory action based on health or 

safety risks subject to Executive Order 

13045 (62 FR 19885, April 23, 1997); 

• Is not a significant regulatory action 

subject to Executive Order 13211 (66 FR 

28355, May 22, 2001); 

• Is not subject to requirements of 

Section 12(d) of the National 

Technology Transfer and Advancement 

Act of 1995 (15 U.S.C. 272 note) because 

application of those requirements would 

be inconsistent with the CAA; and 

• Does not provide EPA with the 

discretionary authority to address, as 

appropriate, disproportionate human 

health or environmental effects, using 

practicable and legally permissible 

methods, under Executive Order 12898 

(59 FR 7629, February 16, 1994). 

In addition, this rule does not have 

tribal implications as specified by 

Executive Order 13175 (65 FR 67249, 

November 9, 2000), because the SIP is 

not approved to apply in Indian country 

located in the State, and EPA notes that 

it will not impose substantial direct 

costs on tribal governments or preempt 

tribal law. 

List of Subjects in 40 CFR Part 52 

Environmental protection, Air 

pollution control, Intergovernmental 

relations, Nitrogen dioxide, Ozone, 

Reporting and recordkeeping 

requirements, Volatile organic 

compounds. 

Authority: 42 U.S.C. 7401 et seq. 

Dated: July 12, 2010. 

Carol Rushin, 

Acting Regional Administrator, Region 8. 

[FR Doc. 2010–17810 Filed 7–20–10; 8:45 am] 

BILLING CODE 6560–50–P 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 300 

[EPA–HQ–SFUND–1987–0002; FRL–9177–1] 

National Oil and Hazardous 

Substances Pollution Contingency 

Plan; National Priorities List: Partial 

Deletion of the Rocky Mountain 

Arsenal Federal Facility 

AGENCY: Environmental Protection 

Agency. 

ACTION: Proposed rule, reopening of 

public comment period. 

SUMMARY: The Environmental Protection 

Agency (EPA) Region 8 issued a Notice 

of Intent to Delete portions of the Rocky 

Mountain Arsenal Federal Facility 

(RMA) from the National Priorities List 

(NPL) on June 17, 2010. The portions 

proposed for deletion are the Central 

and Eastern Surface Areas of the OnPost Operable Unit (OU3) including 

surface media and structures (CES) and 

the surface media of the entire Off-Post 

Operable Unit (OU4) (OPS). A formal 

request was made to extend the public 

comment period which is scheduled to 

end on July 19, 2010. In response, EPA 

is reopening the public comment period 

for an additional 30 days concluding on 

August 16, 2010. 

The NPL, promulgated pursuant to 

section 105 of the Comprehensive 

Environmental Response, 

Compensation, and Liability Act 

(CERCLA) of 1980, as amended, is an 

appendix of the National Oil and 

Hazardous Substances Pollution 

Contingency Plan (NCP). The EPA and 

the State of Colorado, through the 

Colorado Department of Public Health 

and Environment (CDPHE), have 

determined that all appropriate 

response actions under CERCLA at the 

CES and OPS, other than operation, 

maintenance, and five-year reviews, 

have been completed. 

This rationale for deleting the CES 

and OPS from RMA has not changed. 

The Federal Register notice for the 

proposed deletion (75 FR 34405) 

discusses this rationale in detail. 

DATES: The comment period for the 

proposed rule published June 17, 2010, 

at 75 FR 34405, is reopened. Comments 

concerning the proposed partial 

deletion may be submitted to EPA on or 

before August 16, 2010. 

ADDRESSES: Submit your comments, 

identified by Docket ID No. EPA–HQ– 

SFUND–1987–0002, by one of the 

following methods: 

• http://www.regulations.gov: Follow 

the on-line instructions for submitting 

comments. 

• E-mail: chergo.jennifer@epa.gov. 

• Fax: 303–312–7110. 

• Mail: Ms. Jennifer Chergo, 

Community Involvement Coordinator 

(8OC), U.S. EPA, Region 8, 1595 

Wynkoop Street, Denver, Colorado 

80202–1129. 

• Hand Delivery: 1595 Wynkoop 

Street, Denver, Colorado 80202–1129. 

Such deliveries are only accepted 

during the Docket’s normal hours of 

operation, and special arrangements 

should be made for deliveries of boxed 

information. 

Docket: All documents in the docket 

are listed in the http:// 

www.regulations.gov index. Although 

listed in the index, some information is 

not publicly available, e.g., CBI or other 

information whose disclosure is 

restricted by statute. Certain other 

material, such as copyrighted material, 

will be publicly available only in hard 

copy. Publicly available docket 

materials are available either 

electronically in http:// 

www.regulations.gov or in hard copy at: 

—EPA’s Region 8 Superfund Records 

Center, 1595 Wynkoop Street, Denver, 

Colorado 80202–2466. Hours: 8 a.m. 

to 4 p.m. by appointment (call 303– 

312–6473), Monday through Friday, 

excluding legal holidays; and the 

—Joint Administrative Records 

Document Facility, Rocky Mountain 


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