December 6, 2024

New Part 60, Subpart Kc for VOL Storage Vessels Finalized

On October 15, 2024, EPA finalized its NSPS review for volatile organic liquid (VOL) storage vessels, also called VOL storage tanks. [89 FR 68535] The final rule establishes a new Part 60, Subpart Kc, creating more stringent standards for new tanks, and adds electronic reporting to Part 60, Subpart Kb for older tanks. Subpart Kc applies 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 applies to VOL storage vessels with a capacity ≥75 m³ for which construction, reconstruction, or modification commenced after July 23, 1984, but on or before October 4, 2023.

Compared to Subpart Kb, Subpart Kc:

Eliminates the §60.110b(b) exemptions tied to vapor pressure applicability thresholds but adds an exemption at §60.110c(b)(8) for vessels that only store VOL with a maximum true vapor pressure (MTVP) <0.25 psia (1.7 kPa absolute).
Eliminates the §60.110b(d)(8) exemption for vessels subject to Part 63, Subpart GGGG (the vegetable oil production NESHAP).
Reduces the vapor pressure control requirement applicability thresholds from 27.6/5.2 kPa [§60.112b(a)] to 10.3/3.4 kPa (1.5/0.5 psia) [§60.110c(c-d)]. However, vessels below the control requirement applicability thresholds are still subject to the MTVP determination requirement in §60.113c(d) and the dimension/capacity recordkeeping requirement in §60.115c(b). [§60.110c(f)]
Increases VOC control device efficiency from 95% [§60.112b(a)(3)(ii)] to 98% [§60.112c(d)(3)].
Sets additional monitoring requirements for tanks with internal floating roofs, such as lower explosive limit monitoring [§60.112c(b)(16)].
Disallows 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); 89 FR 83304]
Creates degassing requirements for storage vessels operating with a closed vent system routed to a control device, gas system, or process and storage vessels with a design capacity ≥1,000,000 gal (3,790 m³) containing a VOL that, as stored, has a MTVP ≥1.5 psia (10.3 kPa). [§60.112c(e)]
Removes 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)]
Allows facilities to comply with Subpart Kc in lieu of Subparts K, Ka, and Kb [§60.110c(h)], or in lieu of Part 63, Subpart WW when operating a storage vessel with an internal or external floating roof.

Subparts Kb and Kc require electronic reporting through the Compliance and Emissions Data Reporting Interface (CEDRI), accessible via EPA’s Central Data Exchange.

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