Colorado Regulation No. 7: Control of ozone precursors and control of hydrocarbons via oil and gas emissions

Last updated: 14 January 2020

Transmission, Storage Segment:

2020 marks the beginning of a performance-based program to reduce methane emissions from transmission and storage facilities (Part D, Sec. IV). By 31 Dec 2020, each owner/operator must develop a company-specific plan; by 1 Jan 2021, they must begin to implement the plan and collect  emissions inventory data. A steering committee will set a segment-wide emissions intensity target by 1 Oct 2023, to be achieved by 1 Jan 2025. Annual emissions inventory reporting is required, with certifications.

Oil/NGL storage, processing, handling:

Operators must minimize leakage of VOCs, hydrocarbons “to the extent reasonably practicable,” through vapor recovery systems or flares. As of 1 May 2014, new flares must have auto-igniters; existing flares must be retrofitted by 1 May 2016 (Part D, Sec. IIC).



By 1 Jan 2015, open lines must have caps, plugs or valves that seal except when in use (Part D, Sec. IIC).



By 1 Jan 2015, operators must reduce emissions from wet seal centrifugal compressors 95%, and replace rod packing on reciprocating compressors every 26,000 hours of operation/36 months (Part D, Sec. IIC).



By 1 Feb 2009, operators must replace new continuous bleed pneumatic controllers at upstream sites with low-bleed controllers (replace/retrofit existing controllers by 1 May 2009) (Part D, Sec. IID). Natural gas processing plants: as of 1 Jan 2018, operators must install zero-bleed controllers; replace/retrofit existing controllers by 1 May 2018. High-bleed controllers must be tagged, inspected monthly, and maintained. Recordkeeping, annual reporting required.


Storage tanks: Some of the storage tank requirements only apply in parts of the state with serious ozone pollution.

Larger storage tanks must meet a 95% VOC reduction target or route to a flare with 98% efficiency. In 2014, regulators lowered the threshold for larger tanks to 6 tpy, down from 20 tpy; beginning 1 Mar 2020, this threshold is lowered again to 2 tpy, and now applies state-wide.

Through March 2020, also requires “system-wide” VOC reductions across all tanks with capacity > 2 tpy commonly owned (unless total emissions  < 30 tpy): 90% during ozone season (May through Sept), and 70% during the rest of the year.  Owners must report air pollution control equipment used and document compliance with the seasonal limits.

Flares must be designed for 98% efficiency (Part D, Sec. IIC) and have auto-igniters (Part D, Sec. I).


From 1 May 2014, operators must conduct audio-visual-olfactory inspections of tanks not more than every 7 days/at least every 31 days (unless dangerous, difficult, or inaccessible); inspect emissions monitoring systems, and implement tank emission management plans (Part D, Sec. IIC).



By 1 May 2015, increased reduction target from 90 – 95% for new glycol dehydrators emitting > 2 tpy (or existing within 1,320 feet of a building/outside activity area; otherwise 6 tpy) (Part D, Sec. IIC).



Beginning 1 Jan 2015, operators must conduct LDAR at wells and compressor stations, on a one-time, annual, quarterly, or monthly basis depending on magnitude of emissions. As of 2020, facilities with estimated VOC emissions > 2 tpy must inspect at least semi-annually; with > 2 tpy and within 1,000 feet of an “occupied area” (a residence, school, large commercial establishment, or outdoor venue), at least quarterly; and with > 12 tpy and within 1,000 feet of an “occupied area”, at least monthly (Part D, Sec. IIC).  Exceptions for unsafe, difficult or inaccessible situations (defined terms). Recordkeeping and annual reporting required (Part D, Sec. IIC). As of 2020, LDAR must cover controllers.


Separator Gas:

Must send to a gathering line, an air pollution control system with 95% efficiency, or a flare with 98% efficiency (Part D, Sec. IIC).


Liquids Unloading:

Must minimize venting as of 2014; enhanced recordkeeping and reporting, as of 2020 (Part D, Sec. IIC).

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