Plain answer
A closed-vent system and control device may replace a specific Subpart BB component standard or serve as a Subpart CC unit-control option. It does not make the equipment or unit nonapplicable. Before selecting that path, compare the avoided inspections with the performance demonstration, continuous monitoring, closed-vent inspection, maintenance, repair, and recordkeeping the control route creates.
The important distinction
Subpart BB and Subpart CC do not send every controlled system through the same provision.
| Subpart BB | Subpart CC | |
|---|---|---|
| Core provision | §265.1060 directs covered closed-vent systems and control devices to §265.1033 | §265.1088 contains its own standards and incorporates selected Subpart AA provisions |
| What it can replace | Only the particular component standard that expressly allows the route | A specified tank, surface-impoundment, or Container Level 3 control option |
| What remains | Subpart BB applicability, identification, records, and unaffected component standards | Subpart CC applicability, waste determinations, unit designation, inspections, and records |
“Everything is vented to carbon” is therefore not a complete compliance determination. The file must identify the regulatory option selected for each component or unit.
Subpart BB allows controls for specific equipment
Subpart BB expressly recognizes a closed-vent and control-device route in several places, but not as a blanket substitute for the entire equipment-leak program.
| Equipment or activity | How the control route works |
|---|---|
| Pumps in light-liquid service | A system capturing seal leakage and routing it to a compliant control device can replace the pump requirements in §265.1052(a) through (e). |
| Compressors | A system capturing seal leakage can replace specified compressor seal-system requirements under §265.1053(h). |
| Pressure-relief devices in gas or vapor service | Capturing and routing leakage can replace the no-detectable-emissions and post-release requirements under §265.1054(a) and (b). |
| Sampling connections | Purged process fluid may be returned, recycled, routed to a compliant waste-management unit, or routed to a compliant control device. |
| Valves | A control device is not a general alternative to routine valve monitoring. Section 265.1059(c) addresses control of purged material when using a specific delay-of-repair provision. |
| Heavy-liquid equipment, flanges, and connectors | Subpart BB generally relies on response to evidence of a potential leak, not a blanket control-device substitution. |
When §265.1060 applies, it directs the closed-vent system and control device to §265.1033. That can bring in design efficiency, device-specific continuous parameter monitoring, daily review of readings, closed-vent inspection, repair deadlines, carbon-replacement provisions, and operating-record documentation.
Subpart CC uses its own control-device standard
Under Subpart CC, enclosing or covering a tank, surface impoundment, or container and venting it to a control device is a compliance option within the subpart. The unit remains subject, and the applicable waste determinations and records remain necessary.
Section 265.1088 requires the closed-vent system to route vapors to a qualifying device, meet the §265.1033(j) design options, address bypass devices, and undergo the referenced closed-vent inspections. The control device generally must achieve at least 95-percent reduction or meet the specified combustion or flare criteria.
- A flow indicator or seal or lock on a bypass that could divert vapors around the control device
- Monthly inspection when a seal or locking device is used on the bypass
- A maximum of 240 hours per year of planned routine maintenance while the device is off specification
- Correction of malfunctions as soon as practicable
- No active venting to an unavailable or malfunctioning device, except for specified safety or corrective-action circumstances
- Performance testing or a qualifying design analysis, subject to the listed exceptions
- Continuous device-specific parameter monitoring and review of readings at least once each operating day
Recordkeeping is principally under §265.1090. Subpart CC incorporates selected Subpart AA provisions, but it does not simply adopt §265.1033 wholesale.
What the control route may remove, and what it adds
May replace
- A specifically identified BB component standard
- A tank cover or other unit-control route where the applicable CC provision allows the controlled enclosure or vented-cover option
- Some component-specific leak response work, depending on the exact election
Can add
- Performance testing or a defensible engineering design analysis
- Continuous device-specific parameter monitoring
- Operating-day review and response to abnormal readings
- Initial and recurring closed-vent inspections or monitoring
- Five-day first-attempt and 15-day repair deadlines for closed-vent defects
- Carbon replacement or regeneration schedules when adsorption is used
- Long-term design, inspection, maintenance, malfunction, and operating records
If removed carbon is itself a hazardous waste, §265.1033(m) prescribes how it must be managed. The provision does not automatically make all spent carbon hazardous; that classification requires its own hazardous-waste determination.
The practical decision test
Controls may be justified by emission limits, worker exposure, another air requirement, or process needs. Simplifying RCRA compliance should not be assumed.
- Identify the exact regulatory paragraph the control device will satisfy for each component or unit.
- Separate the Subpart BB pathway from the Subpart CC pathway.
- Confirm capture, closed-vent, bypass, control-efficiency, and monitoring requirements.
- Define the operating parameter and acceptable range for each device.
- Assign daily review, inspection, calibration, carbon-change, malfunction, and repair responsibilities.
- Price the monitoring and recordkeeping program over the life of the unit, not only the equipment installation.
- Confirm that operations can stop or isolate vapor flow when the device is unavailable.
Bottom line
The component-level obligation is often periodic and distributed. The control-device obligation is continuous and concentrates compliance in the performance of one system.Start with applicability
Not sure whether AA, BB, or CC applies?
Apply the three unit and concentration tests before choosing a control strategy.
Read the AA, BB, and CC applicability guide ↗Evaluating a control strategy?
ACP can compare the proposed design with the actual RCRA monitoring and operating burden.
Primary references
This field note is a general overview. The correct pathway depends on the equipment type, waste service, selected compliance option, control-device design, facility status, and authorized state program.