Colorado Department of Public Health and Environment / Air Pollution Control Division 

Denver Metropolitan Area and North Front Range 

8-Hour Ozone 

State Implementation Plan 

Technical Support Document 

Determination of Rule Effectiveness 

For 

Proposed Pneumatic Controller and Condensate Tank Regulation

DRAFT 

November 10, 2008 

Colorado Department of Public Health and Environment 

Air Pollution Control Division 

4300 Cherry Creek Drive South 

Denver, Colorado 80246 

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DRAFT - Denver Metro Area/North Front Range 8-hour Ozone SIP 

Determination of Rule Effectiveness for Proposed Pneumatic Controller and Condensate Tank Regulation 
Colorado Department of Public Health and Environment / Air Pollution Control Division 

 

Table of Contents 

1. PNEUMATIC CONTROLLER REGULATION RULE EFFECTIVENESS DETERMINATION..............1

1.1. BACKGROUND ................................................................................................................................................1

1.2. DEFINITION OF RULE EFFECTIVENESS ............................................................................................................1

1.3. DISCUSSION ....................................................................................................................................................1

2. CONDENSATE TANK REGULATION RULE EFFECTIVENESS DETERMINATION ...........................3

2.1. COMPLIANCE ISSUES WHICH INFORM RULE EFFECTIVENESS .........................................................................3

2.2. USE OF EPA RE GUIDANCE FOR CONDENSATE TANKS ..................................................................................4

3. REFERENCES ......................................................................................................................................................5

 

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DRAFT - Denver Metro Area/North Front Range 8-hour Ozone SIP 

Determination of Rule Effectiveness for Proposed Pneumatic Controller and Condensate Tank Regulation 
Colorado Department of Public Health and Environment / Air Pollution Control Division 

1. Pneumatic Controller Regulation Rule Effectiveness 

Determination 

1.1. Background 

Many types of process control devices can be used to operate valves that regulate pressure, 

flow, temperature, and liquid levels. These devices can be operated pneumatically, 

electrically, or mechanically. A pneumatic device is an instrument that is actuated by gas. 

Most of the devices used by the natural gas industry are pneumatically operated. Although 

instrument air is commonly used to power pneumatic devices at gas processing facilities, 

where electricity is readily available and can be used to compress air, the majority of 

natural gas industry pneumatic devices are powered by natural gas. 

As part of normal operation, most pneumatic devices emit, or “bleed”, gas to the 

atmosphere, either continuously or intermittently. Pneumatic devices generally consist of a 

controller and a valve. Bleed rates are associated with the controller. Gas is vented to 

atmosphere during actuation when valves open and/or close; however, vent rates are not 

significant and are the same whether a high-bleed or low-bleed controller is used. The 

proposed regulation addresses bleed rates from controllers that are actuated by natural gas. 

1.2. Definition of Rule Effectiveness 

Rule Effectiveness (RE) is a term that describes a method to account for the reality that not 

all facilities covered by a rule are in compliance with the rule 100% of the time. Rule 

effectiveness reflects the actual ability of a regulatory program to achieve the emission 

reductions required by regulation. The concept of applying rule effectiveness in a State 

Implementation Plan (SIP) emission inventory has evolved from the observation that 

regulatory programs (and associated compliance rates) may be less than 100 percent 

effective for some source categories. 

The Air Pollution Control Division (Division) reviewed the latest Environmental Protection 

Agency (EPA) guidance (EPA-454/R-05-001), Appendix B “Revised Rule Effectiveness”, 

August 2005, for Non-Point Sources) to determine an appropriate RE value. The guidance 

provides emission inventory preparers with a listing of factors that are most likely to affect 

RE. 

1.3. Discussion 

The Division determined that the required factors for Range 2, with a corresponding RE of 

70-85%, have been satisfied as discussed below: 

• Sources in Compliance- In June 2008 the Division prepared and sent, via Section 

111 letters, requests to the oil and gas industry in the Denver Metro Area and North 

Front Range (DMA/NFR) non-attainment area (NAA). (Letters were mailed in 

accordance with the Division’s authority found in Air Quality Control Commission 

(AQCC) Common Provision Regulation Section II.C. and Section 25-7-111(2)(i), 

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DRAFT - Denver Metro Area/North Front Range 8-hour Ozone SIP 

Determination of Rule Effectiveness for Proposed Pneumatic Controller and Condensate Tank Regulation 
Colorado Department of Public Health and Environment / Air Pollution Control Division 

C.R.S. This is an official method of gathering information from industry.) The 

Section 111 letters included requests for submittal of information related to the 

presence of high- and low-bleed devices (as described above) and indicated that 

affected sources must either report these controllers to the Division (via Air 

Pollution Emission Notices or a permit application, if such thresholds were reached) 

or replace the controllers with low-bleed devices. Industry reported that all but 

approximately 85 controllers had been replaced or would be replaced by November 

2008. At a minimum, industry had committed to converting approximately 95 

percent of high-bleed devices to low-bleed by November 2008. 

• Compliance Certification – As described above, affected companies certified their 

retrofitting of pneumatic controllers via their response to the Division’s Section 111 

letters. These signed and dated response letters are on file with the Division. 

• Compliance Assistance – The Division, with industry and the Regional Air Quality 

Council (RAQC), hosted a presentation on pneumatic controllers in June 2008. This 

presentation allowed industry to learn the simplicity of retrofitting devices. EPA 

GasSTAR information was provided as an additional resource. The Division 

provided one-on-one customer service to a number of operators who requested 

additional information and guidance. These consultations allowed the Division an 

opportunity to clarify technical aspects of pneumatic controllers and to provide an 

example emission calculation. 

A RE value of 83 percent was used by the Division in recent SIP modeling, although it may 

have been appropriate to use a higher value. Many companies have already begun 

implementing the proposed regulation voluntarily, as evidenced from responses to a 

Section 111 information request letter as described above. Once the proposed regulation is 

implemented, companies would be required to obtain permission from the Division to 

continue using existing high-bleed pneumatic devices (e.g., safety exemptions), or to install 

new ones. Therefore, it is anticipated that the conversion percentage may rise above 95 

percent. 

The Division has determined that the required factors for Range 2, with a RE of 70-85%, 

for pneumatic controllers have been satisfied. 

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DRAFT - Denver Metro Area/North Front Range 8-hour Ozone SIP 

Determination of Rule Effectiveness for Proposed Pneumatic Controller and Condensate Tank Regulation 
Colorado Department of Public Health and Environment / Air Pollution Control Division 

2. Condensate Tank Regulation Rule Effectiveness 

Determination 

In the ozone non-attainment area, Regulation 7 requires a condensate tank VOC emission control 

program during the 23 week ozone season (May 1 – Sep 30) that is averaged over the whole 

system of tank batteries except for small operators with emissions under 30 tpy. The system-wide 

control program has been implemented over three years to accommodate availability and 

installation of control devices on thousands of tank batteries. In the first year (2005), tank 

emissions were required to be reduced by 37.5% system-wide; that figure was increased to 47.5% 

in 2006 and 75% in 2007. Producers are required to report compliance with the system-wide 

control requirements on a weekly basis during the ozone season.

In the Early Action Compact (EAC), the Regulation 7 condensate tank RE of 83% was established 

by the AQCC at a public hearing in December 2006. RE is a term that describes a method to 

account for the reality that not all facilities covered by a rule are in compliance with the rule 100% 

of the time. For the development of the 2008 DMA/NFR Ozone SIP the Division reevaluated RE 

based on a review of system-wide reports from the producers. Since each year of the system-wide 

implementation period had an increased level of stringency in emission controls, the Division 

limited the reconsideration of condensate tank RE to the 2007 ozone season. The 2007 data 

provide an appropriate and representative sample of compliance rates, which should best reflect 

the fully implemented 75% control specified in the existing rules for 2010 attainment date. 

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2.1. Compliance Issues Which Inform Rule Effectiveness 

As part of the development of revisions to Regulation No. 7 emission controls for 

condensate storage tanks, the Division reviewed the application of RE. 

As part of this rulemaking, the Division has reviewed the 2005, 2006 and 2007 summer 

ozone season compliance histories of operators in the NAA. Such a review has allowed the 

Division to determine operators’ rate of compliance with meeting Regulation No 7 

requirements. In essence, a number of large and small companies continue to have 

challenges with compliance (e.g., failure to meet 75% system-wide control requirements). 

In addition, the Division has weighted individual companies’ Regulation No. 7 compliance 

histories against their VOC contribution in the NAA (as a function of total condensate 

tanks emissions). Such an effort has allowed the Division to gauge how operators in the 

NAA essentially impact VOC emissions. 

The Division reviewed submittals from the 25 companies that were subject to Regulation 

No 7 during the 2005 ozone season. Of these 25 companies, 17 were out of compliance 

with the season’s 37.5% control requirement. Three enforcement cases were opened in 

calendar year 2005 to resolve compliance issues for Regulation No 7. 

For the 2006 ozone season, 16 out of 26 companies subject to Regulation No 7 had at least 

one day of non-compliance with the 47.5% control requirement. There were 12 companies 

DRAFT - Denver Metro Area/North Front Range 8-hour Ozone SIP 

Determination of Rule Effectiveness for Proposed Pneumatic Controller and Condensate Tank Regulation 
Colorado Department of Public Health and Environment / Air Pollution Control Division 

with an average percent control less than the 47.5% requirement for the entire ozone 

season. 

The Division contracted with Weld County to perform inspections of 214 tank batteries in 

the 8-hour ozone attainment area during the 2006 ozone season. Of the 214 inspections, 75 

flares were out of service. Of these 75 cases, the inspector observed flare outages which 

were not reported on the Regulation No 7 emission spreadsheet submittals in 31 cases. (31 / 

214 = 14.5% spreadsheet noncompliance; therefore, compliance rate of 85.5%; another 

data point that supports 83% RE). 

 

2.2. Use of EPA RE Guidance for Condensate Tanks 

The Division reviewed the latest EPA guidance (EPA-454/R-05-001), Appendix B 

“Revised Rule Effectiveness”, August 2005) to determine a RE value. The guidance 

provides emission inventory preparers with a listing of factors that are most likely to affect 

RE. 

The Division determined that the required factors for Range 3, with a corresponding RE of 

81-86% have been satisfied as discussed below: 

• Monitoring: The Division requires sources to monitor control equipment downtime, 

production and emissions from each tank battery. These records are to be reported 

to the Division each year. 

• Compliance History: The facilities have met the compliance schedule, and reports 

have been filed within the required timeframe. 

• Inspections: Unannounced inspections are performed at the facilities. Such 

inspections include the review of the process and control equipment. 

• Control Device Operation and Maintenance: Operators are required to monitor 

control equipment on a weekly basis. 

Thus, these analyses demonstrate that a RE value of 83% is appropriate to apply to 

condensate tanks in the NAA. 

The Division has three years’ experience with the system-wide approach. Overall 

compliance has improved over the past three years. However, on-site inspections and 

reported information indicate a compliance disparity between large producers and small 

producers. Large producers, which predominate the number of tanks and their associated 

emissions, have reported fairly solid compliance with the system-wide control 

requirements. In fact, VOC-weighted (and hence company-weighted) compliance overall 

shows an approximately 91% compliance throughout the system-wide approach. Since 

these are active enforcement cases, details are not included in this document. Conversely, 

smaller producers have generally had poor reported compliance with the requirements. 

Future inspections by Division staff and local agencies will better bolster our understanding 

of these suspect compliance rates. 

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DRAFT - Denver Metro Area/North Front Range 8-hour Ozone SIP 

Determination of Rule Effectiveness for Proposed Pneumatic Controller and Condensate Tank Regulation 
Colorado Department of Public Health and Environment / Air Pollution Control Division 

3. References 

1. U.S. EPA, 2005. “Emissions Inventory Guidance for Implementation of Ozone and 

Particulate Matter National Ambient Air Quality Standards (NAAQS) and Regional Haze 

Regulations - Appendix B: Revised Rule Effectiveness.” EPA-454/R-05-001. Emissions 

Inventory Group Emissions, Monitoring and Analysis Division. Office of Air Quality 

Planning and Standards. U.S. Environmental Protection Agency. Research Triangle Park, 

NC. August 2005 

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DRAFT - Denver Metro Area/North Front Range 8-hour Ozone SIP 

Determination of Rule Effectiveness for Proposed Pneumatic Controller and Condensate Tank Regulation