Environmental Permitting

Oil and Gas Tank Emissions

Q & A: Oil and Gas Tank VOC Emissions Changes

Q: What prompted the rule changes that came so soon after the April 17, 2012, Final Rule?

A: The 2012 rule, which was promulgated as required under the Clean Air Act (CAA), included the first federal air standards for natural gas wells that are hydraulically fractured, as well as for other O&G  industry sources of VOCs that were not previously regulated by the federal government.  Following the issuance of the final rule, the EPA received petitions for reconsideration from a broad range of O&G  industry groups, environmental groups, and the Texas Commission on Environmental Quality. The EPA considered the petitions and made the changes based on the receipt of “information showing that more storage tanks will be coming online than the agency originally estimated.” The EPA is continuing to consider other aspects of the reconsideration petitions.


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Q: What factors define the regulated universe of O&G tanks covered by the 2013 NSPS changes?

A: Three main attributes define the storage tanks or “affected facilities” that must comply with the new standards:

  • The tanks were constructed after August 23, 2011;
  • The tanks have the potential to emit 6 or more tons per year of VOCs; and
  • The tanks are used to store crude oil, condensate, unrefined petroleum liquids (known as “intermediate hydrocarbon liquids”), or produced water.

Covered storage tanks may be located any place along the production and transmission process, such as from a natural gas well to the distribution system or from the oil well to the point at which oil is transferred to a pipeline.
Tanks that are not covered by the new standards include:

  • Fuel tanks
  • Storage tanks at refineries
  • Tanks with enforceable permit limits under federal, state, local, or tribal authority if those limits are less than 6 tons a year.

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Q: What compliance deadlines were established in the 2013 NSPS rule changes?

A: Tanks that were installed between August 23, 2011, and April 12, 2013 (known as Group 1 tanks) have until April 15, 2015, to control VOC emissions. This is based on the owners’/operators’ determination that the tank has the potential to emit 6 tons of VOCs per year, which was required to have been made by October 2013. The EPA also notes that it did not finalize a proposed requirement that Group 1 tanks control VOC emissions only if there is a change that has the potential to increase VOC emissions, such as the addition of a well supplying that tank.

April 15, 2014, was the deadline for VOC emissions controls for tanks that came online after April 12, 2013 (known as Group 2 tanks) or within 60 days after start-up, whichever is later. This requirement is a two-step process:

  • Within 30 days of start-up, owners/operators must estimate the tank’s potential to emit VOCs above the limit of 6 tons per year and determine whether they are subject to the rule.
  • If they are determined to be subject to the rule, owners/operators have an additional 30 days to control the VOCs emissions.

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