Marine Loading: Subpart Y Meets Subpart CC

While NESHAP Subpart Y remains the primary regulatory framework for marine vessel loading, the operational boundary between it and refinery-wide compliance under MACT CC, etc. has effectively dissolved. Since MACT CC fenceline monitoring requires measurement for the entire property, emissions originating from marine vessels have the potential to be captured in the measured concentrations, exposing refiners to new enforcement vulnerabilities. Refineries are now being targeted for enforcement for the mechanical failures of MACT Subpart Y via data generated from the Subpart CC Refinery MACT fenceline monitoring requirements.

The EPA has identified marine loading as one of the likely sources for elevated fenceline readings. Specific marine loading operations deficiencies cited include:

• 𝐏𝐨𝐨𝐫 𝐋𝐨𝐚𝐝𝐢𝐧𝐠 𝐀𝐫𝐦 𝐎𝐩𝐞𝐫𝐚𝐭𝐢𝐨𝐧: Leaks and drips caused by mechanical failure or operator error.
• S𝐥𝐨𝐩 𝐖𝐚𝐬𝐭𝐞 𝐌𝐢𝐬𝐡𝐚𝐧𝐝𝐥𝐢𝐧𝐠: Improper disposal of material dripping from loading arms
• 𝐍𝐨𝐧-𝐕𝐚𝐩𝐨𝐫-𝐓𝐢𝐠𝐡𝐭 𝐁𝐚𝐫𝐠𝐞𝐬: Use of vessels that fail to maintain integrity during the loading cycle.
• 𝐏𝐫𝐞𝐬𝐬𝐮𝐫𝐞 𝐑𝐞𝐥𝐢𝐞𝐟 𝐕𝐚𝐥𝐯𝐞 (𝐏𝐑𝐕) 𝐋𝐢𝐟𝐭 𝐄𝐯𝐞𝐧𝐭𝐬: PRVs relieving while a barge is docked, releasing concentrated vapors directly into the path of fenceline samplers.

On March 4, 2026, EPA proposed revisions to NESHAP Subpart Y. Key proposed changes include:

• 𝐄𝐪𝐮𝐢𝐩𝐦𝐞𝐧𝐭 𝐋𝐞𝐚𝐤 𝐃𝐞𝐭𝐞𝐜𝐭𝐢𝐨𝐧 𝐚𝐧𝐝 𝐑𝐞𝐩𝐚𝐢𝐫 (𝐋𝐃𝐀𝐑): Method 21 monitoring must occur during active loading, and leak repairs completed within 15 days.
  • 𝘛𝘩𝘦𝘴𝘦 𝘱𝘳𝘰𝘷𝘪𝘴𝘪𝘰𝘯𝘴 𝘸𝘪𝘭𝘭 𝘩𝘦𝘭𝘱 𝘢𝘥𝘥𝘳𝘦𝘴𝘴 𝘭𝘰𝘢𝘥𝘪𝘯𝘨 𝘢𝘳𝘮, 𝘣𝘢𝘳𝘨𝘦 𝘭𝘦𝘢𝘬𝘴 𝘢𝘯𝘥 𝘗𝘙𝘝 𝘭𝘪𝘧𝘵𝘴.
• 𝐄𝐧𝐡𝐚𝐧𝐜𝐞𝐝 𝐅𝐥𝐚𝐫𝐞 𝐌𝐨𝐧𝐢𝐭𝐨𝐫𝐢𝐧𝐠: Stricter combustion efficiency requirements.
• 𝐌𝐚𝐧𝐝𝐚𝐭𝐨𝐫𝐲 𝐏𝐞𝐫𝐢𝐨𝐝𝐢𝐜 𝐏𝐞𝐫𝐟𝐨𝐫𝐦𝐚𝐧𝐜𝐞 𝐓𝐞𝐬𝐭𝐢𝐧𝐠: Moving away from one-time initial tests.
  • 𝘛𝘩𝘦𝘴𝘦 𝘵𝘸𝘰 𝘱𝘳𝘰𝘷𝘪𝘴𝘪𝘰𝘯𝘴 𝘸𝘪𝘭𝘭 𝘩𝘦𝘭𝘱 𝘦𝘯𝘴𝘶𝘳𝘦 𝘱𝘳𝘰𝘱𝘦𝘳 𝘤𝘰𝘯𝘵𝘳𝘰𝘭 𝘥𝘦𝘷𝘪𝘤𝘦 𝘰𝘱𝘦𝘳𝘢𝘵𝘪𝘰𝘯 𝘢𝘯𝘥 𝘳𝘦𝘤𝘰𝘷𝘦𝘳𝘦𝘥 𝘷𝘢𝘱𝘰𝘳 𝘥𝘦𝘴𝘵𝘳𝘶𝘤𝘵𝘪𝘰𝘯.
• 𝐑𝐞𝐦𝐨𝐯𝐚𝐥 𝐨𝐟 𝐒𝐭𝐚𝐫𝐭𝐮𝐩, 𝐒𝐡𝐮𝐭𝐝𝐨𝐰𝐧, 𝐚𝐧𝐝 𝐌𝐚𝐥𝐟𝐮𝐧𝐜𝐭𝐢𝐨𝐧 (𝐒𝐒𝐌) 𝐄𝐱𝐞𝐦𝐩𝐭𝐢𝐨𝐧𝐬: Meeting emission standards at all times.

TRICORD has been working with both refining and chemical facilities on marine loading and fenceline compliance and is well-posed to support industry with source specific issues. Reach out to your TRICORD contact or Joe Ibanez at Joe.Ibanez@TRICORDConsulting.com to discuss your fenceline compliance strategy!