40 C.F.R. §§ 49.4173–49.4176

For oil and natural gas sources that began operations before February 6, 2023, the VOC emissions control requirements of this section apply when the source-wide potential for VOC emissions from the collection of all storage vessels, glycol dehydrators, and pneumatic pumps is equal to or greater than 4 tpy, as determined according to this section. The potential for VOC emissions must be calculated using a generally accepted model or calculation methodology, based on the maximum average daily throughput determined for a 30-day period of production during the 12 months before the compliance deadline for the affected source under this rule. The determination may take into account requirements under a legally and practicably enforceable limit in an operating permit or other federally enforceable requirement. You must reevaluate the source-wide VOC emissions from the collection of all storage vessels, glycol dehydrators and pneumatic pumps for each modification to an existing source; or

For oil and natural gas sources that began operations on or after February 6, 2023, the VOC emissions control requirements of this section apply upon startup of operation.

Modification to an oil and natural gas source requires a re-evaluation of the source-wide VOC emissions from the collection of all storage vessels, glycol dehydrators and pneumatic pumps. Adding production from a new well or increasing production at an existing well is considered a modification of a well site. Increasing maximum throughput at a tank battery, compressor station or natural gas processing plant is considered a modification.

You must reduce VOC emissions from each storage vessel by at least 95.0 percent on a continuous basis according to paragraph (c)(1)(i) or (ii) of this section. You must equip each storage vessel with a cover that meets the conditions specified in § 49.4176(c), and must route all flashing, working, standing and breathing losses from the storage vessels through a closed-vent system that meets the conditions specified in § 49.4176(d) to:

You must maintain the source-wide uncontrolled actual VOC emissions from the collection of all storage vessels, glycol dehydrators, and pneumatic pumps at an oil and natural gas source at less than 4 tpy. Before using the uncontrolled actual VOC emission rate for compliance purposes, you must demonstrate that the uncontrolled actual VOC emissions have remained at less than 4 tpy, as determined monthly for 12 consecutive months. After such demonstration, you must determine the uncontrolled actual VOC emission rate each month. The uncontrolled actual VOC emissions must be calculated using a generally accepted model or calculation methodology. Monthly calculations must be based on the average throughput of the source for the month. Monthly calculations must be separated by at least 14 days. You must comply with paragraph (c)(1) of this section within 30 days of the monthly emissions determination required in this section if the determination indicates that VOC emissions from the collection of all storage vessels, glycol dehydrators, and pneumatic pumps at your oil and natural gas source increased to 4 tpy or greater.

Except as provided in paragraph (c)(4) of this section, if you use a control device to reduce emissions from your storage vessels, you must equip each storage vessel with a cover that meets the requirements of § 49.4176(c).

If you use a floating roof to reduce emissions, you must meet the requirements of § 60.112b(a)(1) or (2) and the relevant monitoring, inspection, recordkeeping, and reporting requirements in 40 CFR part 60, subpart Kb.

After a minimum of 12 consecutive months of operation at a source that begins operation on or after February 6, 2023, controls may be removed if the source-wide uncontrolled actual VOC emissions from the collection of all storage vessels, glycol dehydrators, and pneumatic pumps has been maintained at a rate less than 4 tpy, as determined according to paragraph (c)(2) of this section.

You must reduce VOC emissions from each glycol dehydration unit process vent by at least 95.0 percent on a continuous basis according to paragraphs (c)(1)(i) and (ii) of this section. You must route all glycol dehydration unit process vent emissions through a closed-vent system that meets the conditions specified in § 49.4176(d) to:

You must maintain the source-wide uncontrolled actual VOC emissions from the collection of all storage vessels, glycol dehydrators, and pneumatic pumps at an oil and natural gas source at less than 4 tpy for 12 consecutive months in accordance with the procedures specified in § 49.4173(c)(2).

You must reduce VOC emissions from each pneumatic pump by at least 95.0 percent on a continuous basis according to paragraph (c)(1)(i) or (ii) of this section. You must route all pneumatic pump emissions through a closed-vent system that meets the conditions specified in § 49.4176(d) to:

You must maintain the source-wide uncontrolled actual VOC emissions from the collection of all storage vessels, glycol dehydrators, and pneumatic pumps at an oil and natural gas source at less than 4 tpy for any 12 consecutive months in accordance with the procedures specified in § 49.4173(c)(2).

Each cover and all openings on the cover (e.g., access hatches, sampling ports, pressure relief valves (PRV), and gauge wells) must form a continuous impermeable barrier over the entire surface area of the crude oil, condensate, intermediate hydrocarbon liquids, or produced water in the storage vessel.

Each cover opening must be secured in a closed, sealed position (e.g., covered by a gasketed lid or cap) whenever material is in the unit on which the cover is installed except when it is necessary to use an opening as follows:

Each thief hatch cover must be weighted and properly seated to ensure that flashing, working, standing, and breathing loss emissions are routed through the closed-vent system to the vapor recovery system, the enclosed combustor, or the flare under normal operating conditions.

Each PRV must be set to release at a pressure that will ensure that flashing, working, standing, and breathing loss emissions are routed through the closed-vent system to the vapor recovery system, the enclosed combustor, or the flare under normal operating conditions.

Each closed-vent system must route all captured storage vessel emissions from flashing, working, standing, and breathing losses; glycol dehydration unit process vent emissions; and pneumatic pump emissions from the oil and natural gas source to a gathering pipeline system for sale, use in a process unit, incorporation into a product, or other beneficial purpose, or to a VOC emission control device, as specified in §§ 49.4173 through 49.4175.

All vent lines, connections, fittings, valves, relief valves, and any other appurtenances employed to collect or contain captured storage vessel emissions from flashing, working, standing, and breathing losses; glycol dehydration unit process vent emissions; or pneumatic pump emissions; or to transport such emissions to a gathering pipeline system for sale, use in a process unit, incorporation into a product, or other beneficial purpose, or to a VOC emission control device, as specified in §§ 49.4173 through 49.4175, must be maintained and operated properly at all times.

Each closed-vent system must be designed to operate with no detectable emissions, as demonstrated by the closed-vent system monitoring requirements in § 49.4182(c).

If any closed-vent system contains one or more bypass devices that could be used to divert all or a portion of the captured storage vessel flashing, working, standing, and breathing losses; glycol dehydration unit process vent emissions; or pneumatic pump emissions from entering a gathering pipeline system for sale, use in a process unit, incorporation into a product, or other beneficial purpose, or from being transferred to the VOC emissions control device, the owner or operator must meet one of the requirements in paragraphs (d)(4)(i) or (ii) of this section for each bypass device. Low leg drains, high point bleeds, analyzer vents, open-ended valves or lines, and safety devices are not subject to the requirements applicable to bypass devices.