November 21, 2023

New Part 60, Subpart Kc for VOL Storage Vessels Proposed

On October 4, 2023, EPA proposed its NSPS review for volatile organic liquid (VOL) storage vessels, also called VOL storage tanks. [88 FR 68535] The proposal would establish a new Part 60, Subpart Kc, creating more stringent standards for new tanks, and would also require electronic reporting under Part 60, Subpart Kb for older tanks. Once finalized, Subpart Kc would apply to each storage vessel with a capacity ≥20,000 gallons (75.7 m³) storing VOLs for which construction, reconstruction, or modification commences after October 4, 2023. Subpart Kb applicability would be set for VOL storage vessels with a capacity ≥75 m³ for which construction, reconstruction, or modification is commenced after July 23, 1984, but on or before October 4, 2023. The agency estimates approximately 9,100 storage vessels were subject to Subpart Kb in 2022, with an estimated 240 storage vessels becoming new affected facilities under the rule each year. [88 FR 68538] Once this rule is finalized, EPA projects 20% more storage vessels will become subject to Subpart Kc as it will have broader applicability than Subpart Kb. [88 FR 68542]

Changes from Subpart Kb to Subpart Kc

Once finalized, Subpart Kc will be a more stringent standard than Subpart Kb as it will better control emissions of volatile organic compounds (VOCs) and other air pollutants. Compared to Subpart Kb, Subpart Kc will:

Eliminate the §60.110b(b) exemptions tied to vapor pressure applicability thresholds.
Eliminate the §60.110b(d)(8) exemption for vessels subject to Part 63, Subpart GGGG (the vegetable oil production NESHAP).
Reduce the vapor pressure control requirement applicability thresholds from 27.6/5.2 kPa [§60.112b(a)] to 10.3/3.4 kPa [§60.110c(c)].
Increase VOC control device efficiency from 95% [§60.112b(a)(3)(ii)] to 98% [§60.112c(d)(3)].
Set additional monitoring requirements for tanks with internal floating roofs, such as lower explosive limit monitoring [§60.112c(b)(16)].
Disallow the §60.14(e)(4) modification exemption, meaning if the previous content of the storage vessel were below the vapor pressure threshold, then a subsequent change in the liquid stored in the vessel to one above the vapor pressure threshold resulting in increased VOC emissions would be considered a modification and trigger Subpart Kc compliance. [§60.110c(e); 88 FR 68545]
Create degassing requirements for storage vessels operating with a closed vent system routed to a control device. [§60.112c(e)]
Remove the startup, shutdown, and malfunction exemption, consistent with Sierra Club vs. EPA (U.S. Court of Appeals, D.C. Circuit; Docket No. 02-1135; December 19, 2008). [§60.110c(g)]

Additional information and comments

Since Subpart Kb was finalized in 1987, many associated technical methods have been updated or replaced, and Subpart Kc will reference the modern versions of those methods. Subparts Kb and Kc will require electronic reporting through the Compliance and Emissions Data Reporting Interface (CEDRI), accessible via EPA’s Central Data Exchange. Other than changing the applicability dates for Subpart Kb, electronic reporting is the only revision to this subpart.

More information, including the proposed regulatory text for Subparts Kb and Kc and a proposal fact sheet, is available on EPA’s NSPS for VOL storage vessel website. Comments may be submitted through December 8, 2023 via Docket ID No. EPA-HQ-OAR-2023-0358. [88 FR 81019]

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