1. (1) Thief hatches on storage vessels shall be kept closed and latched except during vessel unloading or other maintenance activities.

2. (2) All storage vessels located at a well site that are in operation as of January 1, 2018, with a site-wide throughput of 8,000 barrels or greater of crude oil or 2,000 barrels or greater of condensate per year on a rolling 12-month basis shall comply with R307-506-4(2)(a) unless the exemption in R307-506-4(2)(b) applies.

   1. (a) VOC emissions from storage vessels shall either be routed to a process unit where the emissions are recycled, incorporated into a product and/or recovered, or be routed to a VOC control device that is in compliance with R307-508.

   2. (b) All storage vessels located at a well site shall be exempt from R307-506-4(2)(a) if combined VOC emissions are demonstrated to be less than four tons per year of uncontrolled emissions on a rolling 12-month basis.

      1. (i) VOC working and breathing losses, and flash emissions shall be calculated using direct site-specific sampling data and any software program or calculation methodology in use by industry that is based on AP-42 Chapter 7.
3. (3) All storage vessels that begin operations on or after January 1, 2018, are required to control VOC emissions in accordance with R307-506-4(2)(a) upon startup of operation for a minimum of one year.

4. (4) An emergency storage vessel located at a well site shall be exempt from R307-506-4(2)(a), if it meets the following requirements:

   1. (i) The emergency storage vessel shall not be used as an active storage tank.

      1. (ii) The owner or operator shall empty the emergency storage vessel no later than 15 days after receiving fluids.
      2. (iii) The emergency storage vessel shall be equipped with a liquid level gauge or equivalent device.

5. (5) An owner or operator that is required to control emissions in accordance with R307-506-4(2) and R307-506-4(3) shall inspect at least once a month each closed vent system, including vessel openings, thief hatches, and bypass devices, for defects that can result in air emissions according to 40 CFR 60.5416a(c).

   1. (a) If defects are discovered, the defects shall be corrected or repaired within 15 days of identification.
6. (6) Modification to a well site shall require a re-evaluation of site-wide throughput and/or emissions in accordance with R307-506-4(2).
7. (7) After a minimum of one year of operation, controls may be removed if site-wide throughput is less than 8,000 barrels of crude oil or 2,000 barrels of condensate on a rolling 12-month basis or uncontrolled actual emissions are demonstrated to be less than four tons per year.

KEY: air pollution, oil, gas

Date of Last Change: March 5, 2018

Notice of Continuation: February 1, 2023

Authorizing, and Implemented or Interpreted Law: 19-2-104(1)(a)