DEPARTMENT OF PUBLIC HEALTH AND ENVIRONMENT 

Air Quality Control Commission 

REGULATION NUMBER 7 

CONTROL OF OZONE VIA OZONE PRECURSORS 

(EMISSIONS OF VOLATILE ORGANIC COMPOUNDS AND NITROGEN OXIDES) 

5 CCR 1001-9 

Outline of Regulation 

I. Applicability 

II. General Provisions 

III. General Requirements for Storage and Transfer of Volatile Organic Compounds 

IV. Storage of Highly Volatile Organic Compounds 

V. Disposal of Volatile Organic Compounds 

VI. Storage and Transfer of Petroleum Liquid 

VII. Crude Oil 

VIII.Petroleum Processing and Refining 

IX. Surface Coating Operations 

X. Use of Solvents for Degreasing and Cleaning 

XI. Use of Cutback Asphalt 

XII. Volatile Organic Compound Emissions from Oil and Gas Operations 

XIII.Graphic Arts 

XIV. Pharmaceutical Synthesis 

XV. Control of Volatile Organic Compound Leaks from Vapor Collection Systems and Vapor Control 

Systems Located at Gasoline Terminals, Gasoline Bulk Plants, and Gasoline Dispensing 

Facilities 

XVI. Control of Emissions from Stationary and Portable Engines in the 8-Hour Ozone Control Area 

XVII. (State Only, except Section XVII.E.3.a. which was submitted as part of the Regional Haze 

SIP) Statewide Controls for Oil and Gas Operations and Natural Gas-Fired Reciprocating 

Internal Combustion Engines 
XVIII. (State Only) Natural Gas-Actuated Pneumatic Controllers Associated with Oil and Gas 

Operations 

XIX. Statements of Basis, Specific Statutory Authority and Purpose 

Appendix A Colorado Ozone Nonattainment or Attainment Maintenance Areas 

Appendix B Criteria for Control of Vapors from Gasoline Transfer to Storage Tanks 

Appendix C Criteria for Control of Vapors From Gasoline Transfer at Bulk Plants (Vapor Balance 

System) 

Appendix D Minimum Cooling Capacities for Refrigerated Freeboard Chillers on Vapor Degreasers 

Appendix E Test Procedures for Annual Pressure/Vacuum Testing of Gasoline Transport Tanks 

Appendix F Emission Limit Conversion Procedure 

I. Applicability 

I.A. 

I.A.1. The provisions of this regulation shall apply as follows: 

I.A.1.a. All provisions of this regulation apply to the Denver 1-hour ozone 

attainment/maintenance area, and to any nonattainment area for the 1-hour 

ozone standard. 

I.A.1.b. (State Only) All provisions of this regulation apply to any ozone nonattainment 

area, which includes areas designated nonattainment for either the 1-hour or 8-

hour ozone standard, unless otherwise specified in Sections I.A.1.c. and d., 

below. Colorado’s ozone nonattainment or attainment maintenance area maps 

and chronologies of attainment status are identified in Appendix A of this 

regulation. 

I.A.1.c. The provisions of Section V, VI.B.1 and 2, VII.C., and XVII apply statewide. The 

Provisions of Section XVII, XVIII and any other section marked by (State Only) 

are not federally enforceable, unless otherwise identified. 

I.A.1.d. The provisions of Sections XII, and XVI apply in the 8-hour Ozone Control Area. 

XVII. (State Only, except Section XVII.E.3.a. which was submitted as part of the Regional Haze 

SIP) Statewide Controls for Oil and Gas Operations and Natural Gas-Fired Reciprocating 

Internal Combustion Engines 

XVII.A. (State Only) Definitions 

XVII.A.1 “Air Pollution Control Equipment,” as used in this Section XVII, means a 

combustion device or vapor recovery unit. Air pollution control equipment also means 

alternative emissions control equipment and pollution prevention devices and processes 

intended to reduce uncontrolled actual emissions that comply with the requirements of 

Section XVII.B.2. 

XVII.A.2. “Atmospheric”, when used to modify the term “condensate storage tank”, means 

a type of condensate storage tank that vents, or is designed to vent, to the atmosphere. 
XVII.A.3. “Condensate Storage Tank” means any production tank or series of production 

tanks that are manifolded together that store condensate. 

XVII.A.4 “Glycol Natural Gas Dehydrator” means any device in which a liquid glycol 

(including ethylene glycol, diethylene glycol, or triethylene glycol) absorbent directly 

contacts a natural gas stream and absorbs water. 

XVII.B. (State Only) General Provisions 

XVII.B.1. General requirements for air pollution control equipment, prevention of leakage, 

and flares and combustion devices. 

XVII.B.1.a. All air pollution control equipment required by this Section XVII shall be 

operated and maintained pursuant to manufacturer specifications or equivalent to 

the extent practicable, and consistent with technological limitations and good 

engineering and maintenance practices. The owner or operator shall keep 

manufacturer specifications or equivalent on file. In addition, all such air pollution 

control equipment shall be adequately designed and sized to achieve the control 

efficiency rates required by this Section XVII and to handle reasonably 

foreseeable fluctuations in emissions of volatile organic compounds during 

normal operations. Fluctuations in emissions that occur when the separator 

dumps into the tank are reasonably foreseeable. 

XVII.B.1.b. All condensate collection, storage, processing and handling operations, 

regardless of size, shall be designed, operated and maintained so as to minimize 

leakage of volatile organic compounds to the atmosphere to the extent 

reasonably practicable. 

XVII.B.1.c. If a flare or other combustion device is used to control emissions of 

volatile organic compounds to comply with Section XVII, it shall be enclosed, 

have no visible emissions during normal operations, and be designed so than an 

observer can, by means of visual observation from the outside of the enclosed 

flare or combustion device, or by other convenient means approved by the 

Division, determine whether it is operating properly. 

XVII.B.1.d. Any of the effective dates for installation of controls on condensate tanks 

dehydrators and/or internal combustion engines may be extended at the air 

pollution control Division’s discretion for good cause shown 

XVII.B.2. Alternative emissions control equipment shall qualify as air pollution control 

equipment, and may be used in lieu of, or in combination with, combustion devices and 

vapor recovery units to achieve the emission reductions required by this Section XVII, if 

the Division approves the equipment, device or process As part of the approval process 

the Division, at its discretion, may specify a different control efficiency than the control 

efficiencies required by this Section XVII. 

XVII.B.3. Oil refineries are not subject to this section of the rule. 

XVII.B.4. Condensate tanks, dehydrators and internal combustion engines that are subject 

to an emissions control requirement in a federal maximum achievable control technology 

(“MACT”) standard under 40 CFR Part 63, a Best Available Control Technology (“BACT”) 

limit, or a New Source Performance Standard under 40 CFR Part 60 are not subject to 

this Section XVII. 
XVII.C. (State Only) Emission reduction from condensate storage tanks at oil and gas exploration and 

production operations, natural gas compressor stations, natural gas drip stations and natural gas 

processing plants. 

XVII.C.1. Beginning May 1, 2008, owners or operators of all atmospheric condensate 

storage tanks with uncontrolled actual emissions of volatile organic compounds equal to 

or greater than 20 tons per year based on a rolling twelve-month total shall operate air 

pollution control equipment that has an average control efficiency of at least 95% for 

VOCs on such tanks. 

XVII.C.2. For condensate storage tanks with past, uncontrolled actual emissions of volatile 

organic compounds of less than 20 tons per year based on a rolling twelve-month total 

that may become subject to Section XVII.C.1. by virtue of the addition of a newly drilled 

well or the recompletion or stimulation of an existing well, owners or operators of such 

tanks shall have until 90 days after the date of 1st production of the newly drilled, 

recompleted or stimulated well to install and operate any required air pollution control 

equipment. If the owner or operator determines that emissions of volatile organic 

compounds will be below the 20 ton per year threshold, the owner or operator shall notify 

the Division of this determination in writing and include an explanation of the 

methodology used to make this determination. 

XVII.C.3. Monitoring: The owner or operator of any condensate storage tank that is 

required to control volatile organic compound emissions pursuant to this Section XVII.C. 

shall visually inspect or monitor the Air Pollution Control Equipment to ensure that it is 

operating at least as often as condensate is loaded out from the tank, unless a more 

frequent inspection or monitoring schedule is followed. In addition, if a flare or other 

combustion device is used, the owner or operator shall visually inspect the device for 

visible emissions at least as often as condensate is loaded out from the tank. 

XVII.C.4. Recordkeeping: The owner or operator of each condensate storage tank shall 

maintain the following records for a period of five years: 

XVII.C.4.a. Monthly condensate production from the tank. 

XVII.C.4.b. For any condensate storage tank required to be controlled pursuant to 

this Section XVII.C., the date, time and duration of any period where the air 

pollution control equipment is not operating. The duration of a period of nonoperation shall be from the time that the air pollution control equipment was last 

observed to be operating until the time the equipment recommences operation. 

XVII.C.4.c. For tanks where a flare or other combustion device is being used, the 

date and time of any instances where visible emissions are observed from the 

device. 

XVII.D. (State Only) Emission reductions from glycol natural gas dehydrators 

Beginning May 1, 2008, any still vent and vent from any gas-condensate-glycol (GCG) separator (flash 

separator or flash tank), if present, on a glycol natural gas dehydrator located at an oil and gas 

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

shall reduce uncontrolled actual emissions of volatile organic compounds by an average of at least 90 

percent through the use of air pollution control equipment. This Section XVII.D shall not apply to any 

single natural gas dehydrator, or several dehydrators at a single oil and gas exploration and production 

operation/site, 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 based on a rolling twelvemonth total. 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 

XVII.D. shall apply to each natural gas dehydrator within a grouping that has actual uncontrolled 

emissions above two tons per year. 

XVII.E. Control of emissions from new, modified, existing, and relocated natural gas fired reciprocating 

internal combustion engines. 

XVII.E.1. (State Only) The requirements of this Section XVII.E. shall not apply to any 

engine having actual uncontrolled emissions below permitting thresholds listed in 

Regulation Number 3, Part B. 

XVII.E.2. (State Only) New, Modified and Relocated Natural Gas Fired Reciprocating 

Internal Combustion Engines 

XVII.E.2.a. Except as provided in Section XVII.E.2.b. below, the owner or operator 

on any natural gas fired reciprocating internal combustion engine that is either 

constructed or relocated to the state of Colorado from another state, on or after 

the date listed in the table below shall operate and maintain each engine 

according to the manufacturer’s written instructions or procedures to the extent 

practicable and consistent with technological limitations and good engineering 

and maintenance practices over the entire life of the engine so that it achieves 

the emission standards required in Section XVII.E.2.b. Table 1 below. 

XVII.E.2.b. Actual emissions from natural gas fired reciprocating internal combustion 

engines shall not exceed the emission performance standards in Table 1 below 

as expressed in units of grams per horsepower-hour (G/hp-hr) 

TABLE 1 

Maximum 

Engine Hp 

Construction or Relocation 

Date 

Emission Standards 

is G/hp-hr 

NOx CO VOC 

< 100 Hp Any NA NA NA 

≥100 Hp 

and < 500 

Hp 

On or after January 1, 2008 

On or after January 1, 2011 

2.0 

1.0 

4.0 

2.0 

1.0 

0.7 

≥500 Hp On or after July 1, 2007 

On or after July 1, 2010 

2.0 

1.0 

4.0 

2.0 

1.0 

0.7 

XVII.E.3. Existing Natural Gas Fired Reciprocating Internal Combustion Engines 

XVII.E.3.a. (Regional Haze SIP) Rich Burn Reciprocating Internal Combustion 

Engines 
XVII.E.3.a.(i) Except as provided in Sections XVII.3.1.(i)(b) and (c) and 

XVII.E.3.a.(ii), all rich burn reciprocating internal combustion engines 

with a manufacturer's name plate design rate greater than 500 

horsepower, constructed or modified before February 1, 2009 shall install 

and operate both a non-selective catalytic reduction system and an air 

fuel controller by July 1, 2010. A rich burn reciprocating internal 

combustion engine is one with a normal exhaust oxygen concentration of 

less than 2% by volume. 

XVII.E.3.a.(i)(a) All control equipment required by this Section XVII.E.3.a. 

shall be operated and maintained pursuant to manufacturer 

specifications or equivalent to the extent practicable, and 

consistent with technological limitations and good engineering 

and maintenance practices. The owner or operator shall keep 

manufacturer specifications or equivalent on file. 

XVII.E.3.a.(i)(b) Internal combustion engines that are subject to an 

emissions control requirement in a federal maximum achievable 

control technology (“MACT”) standard under 40 CFR Part 63, a 

Best Available Control Technology (“BACT”) limit, or a New 

Source Performance Standard under 40 CFR Part 60 are not 

subject to this Section XVII.E.3.a. 

XVII.E.3.a.(i)(c) The requirements of this Section XVII.E.3.a. shall not 

apply to any engine having actual uncontrolled emissions below 

permitting thresholds listed in Regulation Number 3, Part B. 

XVII.E.3.a.(ii) Any rich burn reciprocating internal combustion engine 

constructed or modified before February 1, 2009, for which the owner or 

operator demonstrates to the Division that retrofit technology cannot be 

installed at a cost of less than $ 5,000 per ton of combined volatile 

organic compound and nitrogen oxides emission reductions (this value 

shall be adjusted for future applications according to the current day 

consumer price index) is exempt complying with Section XVII.E.3.a. 

Installation costs and the best information available for determining 

control efficiency shall be considered in determining such costs. In order 

to qualify for such exemption, the owner or operator must submit an 

application making such a demonstration, together with all supporting 

documents, to the Division by August 1, 2009. 

XVII.E.3.b. (State Only) Lean Burn Reciprocating Internal Combustion Engines 

XVII.E.3.b.(i) Except as provided in Section XVII.E.3.b.(ii), all lean burn 

reciprocating internal combustion engines with a manufacturer's 

nameplate design rate greater than 500 horsepower shall install and 

operate an oxidation catalyst by July 1, 2010. A lean burn reciprocating 

internal combustion engine is one with a normal exhaust oxygen 

concentration of 2% by volume, or greater. 

XVII.E.3.b.(ii) Any lean burn reciprocating internal combustion engine 

constructed or modified before February 1, 2009, for which the owner or 

operator demonstrates to the Division that retrofit technology cannot be 

installed at a cost of less than $ 5,000 per ton of volatile organic 

compound emission reduction (this value shall be adjusted for future 

applications according to the current day consumer price index) is 

exempt complying with Section XVII.E.3.b.(i). Installation costs and the 
best information available for determining control efficiency shall be 

considered in determining such costs. In order to qualify for such 

exemption, the owner or operator must submit an application making 

such a demonstration, together with all supporting documents, to the 

Division by August 1, 2009. 

XIX. Statements of Basis, Specific Statutory Authority and Purpose 

XIX.L. January 8, 2011Outline and Sections I. and XVII. 

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

Colorado Administrative Procedures Act, Section 24-4-103, C.R.S., and the Colorado Air Pollution 

Prevention and Control Act, Sections 25-7-110 and 25-7-110.5, C.R.S (the Act). 

Specific Statutory Authority 

The Colorado Air Quality Control Commission (Commission) promulgates this regulation pursuant to the 

authority granted in Sections 25-7-105(1)(c), C.R.S. (authority to adopt a prevention of significant 

deterioration program); 25-7-109(1)(a) (authority to require the use of air pollution controls); 25-7-

109(2)(a) (authority to adopt emission control regulations pertaining to visible pollutants); and 25-7-

114.4(1) (authority to adopt rules for the administration of permits). 

Basis and Purpose

The Commission intends that the current Regulation Number 7, Section XVII.E.3.a. identifying 

technology-based control requirements for existing rich burn reciprocating internal combustion engines 

(RICE), or rich burn RICE that were constructed or modified prior to February 1, 2009, become a NOx 

emission control measure that is included as part of the Regional Haze SIP and become federally 

enforceable upon EPA approval. 

The technology-based control requirements of Section XVII.E.3.a. reduce NOx. This proposal only 

changes the enforceability of these currently state-only requirements such that they become federally 

enforceable. This proposal does not change emission control, monitoring, recordkeeping or reporting 

requirements. 

The Commission also intends that the following provisions, added in Section XVII.E.3.a.(i)(a) through (c), 

will continue to be effective under the Regional Haze SIP. Specifically, these provisions require good air 

pollution control practices and allow for exemptions from the requirements for existing rich burn RICE. 

The exemptions apply to any existing rich burn RICE either with uncontrolled actual emissions below 

permitting thresholds or that is subject to a New Source Performance Standard (NSPS), National 

Emission Standard for Hazardous Air Pollutants (NESHAP), or Best Available Control Technology (BACT) 

limit. 

Existing lean burn RICE requirements are not incorporated into the Regional Haze SIP, as the associated 

controls do not reduce NOx or SO2. 

Colorado has determined that it is reasonable and appropriate to make these RICE requirements 

federally enforceable in this first planning period, as part of the state’s strategy for addressing reasonable 

progress towards achieving natural visibility conditions in federal Class I areas.