Storage Vessels at Non-Production Site

The Department has issued a new policy memo regarding storage vessels at oil and gas non-production sites; this page is to answer common questions related to this policy.

For questions related to this policy memo contact Craig Thorstenson at 701.328.5188 or by email at

Memo to: Storage Vessel Owner/Operators and Interested Parties

From: Terry L. O'Clair, P.E.—Director, Division of Air Quality

Re: Storage Vessels at Oil and Gas Non-Production Facilities

Date: 27 May 2015

Storage vessels located at oil and gas production facilities are currently subject to requirements established by the Department’s Bakken Pool Oil and Gas Production Facilities Air Pollution Control Permitting & Compliance Guidance (Bakken Guidance). Storage vessels located at non-production facilities are not subject to the Bakken Guidance; however, emissions from the storage vessels remain subject to Chapter 33-15-07 of the North Dakota Air Pollution Control Rules. Subsection 33-15-07-02.1 of the rules states as follows:

No person may cause or permit the emission of organic compounds gases and vapors, except from an emergency vapor blowdown system or emergency relief system, unless these gases and vapors are burned by flares, or an equally effective control device as approved by the department. Minor sources, as determined by the department and not subject to New Source Performance Standards (NSPS), may be granted exemptions to this subsection.

Emissions from a storage vessel at a non-production facility are considered to be adequately controlled for purposes of compliance with the above-referenced subsection if emissions are controlled by a flare, floating roof, vapor recovery unit or equally effective control device.

A storage vessel is considered to be uncontrolled if emissions are not controlled by a flare, floating roof, vapor recovery unit or equally effective control device. Uncontrolled storage vessels at a non-production facility are considered to be minor sources which are not subject to the control requirements of the above subsection if both of the following conditions are met:

  1. Maximum expected annual emissions from each uncontrolled storage vessel are less than 6 tons/year of volatile organic compounds (VOCs); and

  2. Combined maximum expected annual emissions from all uncontrolled storage vessels at the facility are less than 20 tons/year of VOCs.

Storage vessels with maximum expected annual VOC emissions of less than 2 tons/year are not required to control emissions under this policy and are not to be included when calculating emissions from uncontrolled storage vessels at the facility for purposes of this policy.

To be considered adequately controlled for purposes of demonstrating compliance with the requirements of Subsection 33-15-07-02.1 of the rules, storage vessels at a facility must either be controlled in accordance with the requirements of this policy or a site-specific written determination must be obtained from the Department indicating that emissions from each storage vessel are adequately controlled.

All owner/operators required to install control equipment to comply with the requirements of Subsection 33-15-07-02.1 of the North Dakota Air Pollution Control Rules must have the required control equipment installed and operated by January 1, 2016. Failure to install required control equipment will subject the owner/operator of the facility to enforcement action.

Storage Vessels at Oil & Gas Non-Production Facilities Memo


I'm not subject to NSPS Subpart OOOO (40 CFR 60 Subpart OOOO). Does this still apply to me?

Yes. While EPA region 8 is the implementing and enforcement agency for Subpart OOOO; under the North Dakota Administrative Code Article 15 Chapter 7 (33-15-07), which is an approved EPA State Implementation Plan (SIP), the NDDoH can further control the emissions of Volatile Organic Compounds (VOCs). This memo aligns the control requirements of VOCs from oil and gas production sites and from non-production (midstream) facilities.

What are considered controlled sources and exempt from emission calculations?

Any source that already has controls in-place such as internal floating roofs, flares, vapor recovery systems, or similar controls are exempt from the 20 tons per year total VOC emission calculations. Examples include tanks that comply with NSPS Subpart Kb, tanks that are already tied into a flare or vapor recovery system, and tanks that have a maximum expected annual VOC emissions of less than 2 tons per year. Other non-storage vessel emissions of VOCs are not included towards the 20 tons per year total, i.e. an engine on site that emits VOCs is not included.

What is the definition of 'maximum expected annual emissions'?

Maximum expected annual emissions are the annual emissions from the storage vessel(s) calculated based on the maximum expected annual throughput for the storage vessel(s).

Is there a "grandfathering" provision for existing storage vessels?

No. Both new and existing storage vessels are required to comply with the policy by January 1, 2016.

Do owner/operators need to submit a permit application for an existing facility prior to installing controls on a currently uncontrolled storage vessel?

No, a permit application is not required prior to installing control equipment. However, if a Permit to Operate is currently required for the facility, then the owner/operator should notify the Department by letter that the control equipment has been installed. The notification should indicate which storage vessels are now being controlled and should include a revised calculation of potential emissions from the facility.

Last Updated: 01/04/2018