Subpart AA

Subpart AA establishes air emission controls associated with distillation, fractionation, thin-film evaporation, solvent extraction, or air or steam stripping operations that manage hazardous wastes with organic concentrations of at least 10 parts per million weight (ppmw).

The following types of units are subject to the Subpart AA process vent standards:

• Units subject to the permitting standards of Part 270 (i.e., permitted or interim status);
• Recycling units located at hazardous waste management facilities that store hazardous waste prior to recycling or are otherwise subject to the permitting standards of Part 270 (i.e., the facility has a RCRA permit or is in interim status);
• “90-day” accumulation tanks or containers per 40 CFR section 262.17(a) (formerly section 262.34(a)); and
• Miscellaneous certain hazardous waste management units (HWMU) subject to permitting standards, as deemed appropriate.

See 40 CFR Subpart AA, sections 264.1030 through 264.1036 (permitted facilities) or 40 CFR Subpart AA, sections 265.1030 through 265.1035 (interim status facilities) for all of the air emission standards and related requirements for process vents, closed-vent systems and control devices.

• Air Emission Control Requirements

  Owners and operators of facilities subject to Subpart AA must meet one of two standards presented in the regulations. Also, each owner or operator must comply with the test methods and procedures, monitoring, recordkeeping and reporting requirements, as applicable to the affected units. Owners and operators may reduce or destroy the organics in the waste stream to meet either of the following conditions (40 CFR sections 264.1032(a) and 265.1032(a)):                  

  • Reduction of total facility organic air emissions from all process vents covered by the standards to both 3.0 pounds per hour (1.4 kg/h) and 3.1 tons per year (2.8 Mg/y)
                                                                                              OR
  • Reduction of organic air emissions from all affected process vents at the facility by 95 percent by weight using a control device.

  These figures are based on aggregated emissions from all affected process vents at the facility that are subject to Subpart AA. This allows owners and operators to evaluate all alternatives available and achieve the most cost-effective means of complying with the standards.

• Closed-Vent System and Control Devices

  If emissions must be reduced, Subpart AA requires owners and operators to install and operate control devices on affected units at the facility to remove or destroy organics in its emissions. EPA does not specify the type of control device that must be used to achieve these standards. However, individual performance requirements for some types of devices that may be used are presented in the regulations to assist owners and operators in complying with the requirements. These include vapor recovery systems, enclosed combustion devices and flares (see 40 CFR sections 264.1033 (b), (c) and (d) and 265.1033(b), (c) and (d)). Owners and operators may use other types of control devices as long as the emission reduction requirements of 40 CFR sections 264.1032(a) and 265.1032(a) are met.

  In addition to control devices, owners and operators must also install closed-vent systems to route the organics to the control device. A closed-vent system is a system that does not vent emissions to the atmosphere, and one that  is composed of piping and connections that transport gas or vapor from an HWMU to an emission control device (40 CFR sections 264/265.1031). These systems must be designed and operated with no detectable emissions or below atmospheric pressure, and periodically inspected and monitored for emissions (40 CFR sections 264.1033(k)/265.1033(j)).

• Inspection and Monitoring

  Generally, closed-vent systems used to comply with Subpart AA must be monitored at least annually. Any detectable emissions must be controlled as soon as practicable, but typically not later than 15 calendar days after the emission is detected (40 CFR sections 264.1033(l))/265.1033(k)).

  To ensure proper operation and maintenance, owners and operators must monitor and inspect each closed-vent system and control device that is used to comply with Subpart AA (40 CFR sections 264.1033(f), 264.1033(l) or 265.1033(f), 265.1033(k)). The readings of each control device must be inspected at least once each operating day and monitored continuously to ensure proper operation (40 CFR sections 264/265.1033(f) (f)(2), (3)). As with the control device standards, monitoring requirements are given for certain types of control devices that are specified in the regulations. Owners and operators using control devices other than those specifically mentioned must develop documentation indicating proper operation and maintenance of the control device to demonstrate that performance standards are being met (40 CFR sections 264.1033(j)/265.1033(i)).

  If, at any time, inspection of the control device readings indicates that there is a problem with the operation of the control device (i.e., failure to achieve the required organic destruction rate), owners and operators must immediately implement the corrective measures necessary to return the control device to proper operation (40 CFR sections 264/265.1033(f)(3)).

• Recordkeeping and Reporting

  To demonstrate compliance with the standards, Subpart AA requires owners and operators to keep detailed records at the facility. For each unit subject to the Subpart AA standards, design documentation and monitoring, operating, and inspection information can include the following (40 CFR sections 264 /265.1035):

  • Inspection forms and instructions;
  • Monitoring forms, reports and instructions;
  • Maintenance forms and instructions;
  • Employee training (per 40 CFR section 264.16);
  • Written leak detection and repair programs (LDAR); and
  • Other written documents such as planned routine maintenance for the control devices.

  These records must be kept up-to-date and at the facility for at least three years following the date of each occurrence, measurement, maintenance, corrective action, or record (40 CFR sections 264.1035/265.1035). Subpart AA also requires that every six months, owners and operators of permitted facilities report to the Regional Administrator any instances during that period when a control device exceeded or operated outside of its design specifications (as indicated by monitoring activities) for a period longer than 24 hours without being corrected or when a flare operated with visible emissions. The report must indicate the duration and cause of each exceedance and corrective measures taken to remedy the situation. If during the six-month period no such exceedances occur at the facility, the owner and operator need not submit a report to the Regional Administrator (40 CFR section 264.1036).

Subpart BB

The Subpart BB standards of 40 CFR part 264 (permitted facilities) and part 265 (interim status facilities) establish organic air emission controls for equipment leaks. Subpart BB applies to equipment that contains or contacts hazardous wastes with organic concentrations of at least 10 percent by weight (40 CFR sections 264/265.1050). If the equipment contains or contacts such hazardous waste or hazardous waste residues less than 300 hours per calendar year or if the equipment is in vacuum service, it is excluded from the Subpart BB standards, but not from recordkeeping and reporting (40 CFR sections 264.1050(e) and (f)) or 40 CFR 265.1050(d) and (e)). Types of equipment regulated by Subpart BB include pumps, compressors, pressure-relief devices, sampling connection systems, valves, open-ended valves or lines, and other connectors.

Equipment associated with the following types of units is subject to Subpart BB equipment leak standards:

• Units subject to the permitting standards of Part 270 (permitted or interim status),
• Recycling units located at hazardous waste management facilities that store hazardous waste prior to recycling or are otherwise subject to the permitting standards of Part 270 (the facility already has a RCRA permit or is in interim status), and
• “90-day” accumulation tanks or containers per 40 CFR section 262.17(a) (formerly section 262.34(a)),
• Miscellaneous HWMUs subject to permitting standards, as deemed appropriate.

Each piece of equipment that is subject to the Subpart BB standards must be marked in such a manner that it can be readily distinguished from other pieces of equipment and specifically tracked in the facility operating records and reflected in the RCRA permit application. The equipment must be monitored and inspected regularly. Equipment-specific inspection, monitoring and repair requirements are contained in 40 CFR sections 264.1052 through 264.1060 or 40 CFR sections 265.1052 through 265.1060. Most equipment leaks must be repaired within 15 calendar days, although a leaking pressure-relief device must be returned to a condition of no detectable emissions within five calendar days (40 CFR sections 264/265.1054(b)) after a release.

Recordkeeping requirements include: equipment-specific identification; type; design description and location; methods of compliance monitoring (e.g., LDAR programs, including inspection, monitoring and maintenance forms, and instructions and training records. See 40 CFR sections 264/265.1064 for more specific recordkeeping requirements. Written LDAR programs, equipment-specific identification and tracking systems, monitoring and inspections systems and training plans for employees is information also required for the RCRA permitting decision and must be included in the RCRA permit application (40 CFR sections 270.14 and 270.25).

Click below for more information on Subpart BB standards.

• Equipment Leak Control Requirements

  The techniques used to control emissions from equipment leaks under Subpart BB combine equipment standards with inspection and monitoring requirements to ensure compliance with the standards.

  Specific requirements for each type of equipment are given in the regulations. For example, 40 CFR sections 264/265.1053 provides the control standards for compressors in organic hazardous waste service. According to this section, each compressor must be equipped with a seal system that includes a barrier fluid that will prevent organic emissions from leaking to the atmosphere. Specifications are given in the regulations for the compressor seal system and the standards each component must meet. In addition, each barrier fluid must have a sensor that will detect failure of the system.

  Subpart BB requires owners and operators to establish specific LDAR programs. Critical components of the facility’s written LDAR program are the procedures, equipment, training and quality assurance measures the facility uses to accomplish required leak detection monitoring and inspection using specified monitoring devices or means. Depending on the type of equipment being used at the facility, leak detection monitoring and inspection can be accomplished by using devices such as an organic vapor analyzer (OVA) or a flame ionization detector (FID), and occasionally by visual means, or by sense of smell (olfactory). What constitutes a leak for purposes of Subpart BB will depend on the type of equipment being used. For example, valves are considered leaking if an instrument reading of 10,000 ppm or greater is measured (40 CFR sections 264/265.1058(b)).

  Once a leak has been detected, in most cases, repair must be initiated within 5 days and completed within 15 days to remain in compliance with the Subpart BB standards. For example, for a compressor system, each sensor must be checked daily or shall be equipped with an audible alarm that must be checked monthly to ensure that it is functioning properly. If the sensor does indicate a leak, it must be repaired as soon as practicable, but no later than 15 days after the leak was first detected (40 CFR sections 264/265.1053(g)).

• Recordkeeping and Reporting

  Owners and operators must keep detailed records at the facility sufficient to demonstrate compliance with the standards. Such information includes design documentation and monitoring, operating, and inspection information, as applicable, for each piece of equipment affected by Subpart BB. Excluded equipment (i.e., equipment in vacuum service or equipment that contains or contacts hazardous waste or hazardous waste residues for less than 300 hours per calendar year) is required to be identified and listed (40 CFR sections 264/265.1064(g)(5), (6)). These records must be kept up to date and at the facility for at least three years (40 CFR sections 264/265.1064).

  Subpart BB also requires that owners and operators of permitted facilities report to the Regional Administrator every six months, indicating any instances during that period when a valve, pump, compressors for which a leak was not repaired as required by BB, and when a control device exceeded specifications (as indicated by monitoring activities) for longer than 24 hours without being corrected (40 CFR section 264.1065). The reports must indicate dates, duration, cause, and any corrective measures that were taken with respect to control devices. If, during the six-month period, no exceedances occur at the facility, the owner and operator need not submit any report to the Regional Administrator.

  As in Subpart AA, there are no reporting requirements for owners and operators of interim status facilities, or for large quantity generators subject to Subpart BB.

Subpart CC

The subpart CC standards of 40 CFR part 264 (permitted facilities) and part 265 (interim status facilities) apply to owners and operators of facilities that treat, store, or dispose of hazardous waste in tanks, surface impoundments, or containers subject to 40 CFR parts 264/265 subparts I, J, or K. This includes large-quantity hazardous waste generators (1,000 kg/month) accumulating hazardous waste in tanks or containers for less than 90 days (40 CFR section 262.17(a), formerly section 262.34(a)). Additionally, according to 40 CFR section 264.601, RCRA miscellaneous units are subject to Subpart CC requirements, as appropriate, to control volatile organic emissions from the unit (e.g., drum shredders).

See 40 CFR section 264.1080 or 265.1080 to determine if your waste management units are subject to the Subpart CC regulations. See 40 CFR section 264.1082(c) or 265.1083(c) for a description of hazardous wastes and waste management units that are exempt from the Subpart CC standards. Generally, if a hazardous waste has an average volatile organic concentration less than 500 parts per million by weight (ppmw) at the point of waste origination or if the hazardous waste organic content has been reduced by a treatment process to the extent described in 40 CFR section 264.1082(c)(2) or 265.1083(c)(2) prior to placement in the waste management unit, the unit is exempt from the air emission controls required under sections 264.1084 through 264.1087 or 265.1085 through 265.1088. The procedures to be used for determining average volatile organic concentration and other waste characteristics are specified in 40 CFR sections 264.1083 and 265.1084.

• Inspection and Monitoring

  Owners or operators are required to develop and implement a written plan and schedule to perform the inspections and monitoring of the air emission control equipment that are required in 40 CFR sections 264.1084 through 264.1087 for permitted facilities, or 40 CFR 265.1085 through 265.1088 for interim status facilities. Requirements vary by the type of waste management unit and the type of air emission controls used. (40 CFR sections 264.1088/265.1089).

• Emission Control Standards

  Owners or operators are required to manage wastes in units that are closed such that emissions do not escape or are controlled. The emission control standards for non-exempt units (i.e., standards applicable to tanks, surface impoundments, containers, and some miscellaneous units) are detailed below.

  For an exempt waste management unit, the owner or operator is still required to maintain records that document the rationale for the exemption (40 CFR sections 264.1089(j)/265.1090(j)).

• Tanks

  Subpart CC standards applicable to tanks containing hazardous wastes are specified in 40 CFR sections 264.1084 and 265.1085.

  Tank Controls

  1. If a tank’s hazardous waste is greater than or equal to 500 ppmw volatile organic at the point of waste origination, then air emission controls may be required.
  2. Level of control is determined primarily based on tank capacity, maximum organic vapor pressure of hazardous waste in the tank and waste stabilization. The owner or operator is responsible for determining whether Tank Level 1 or Tank Level 2 controls are applicable. Table 1 provides a matrix for determining the applicable control level for a tank.
  3. If a tank qualifies for Level 1 controls, a fixed roof must be used and the owner or operator using Level 1 controls must determine the maximum organic vapor pressure for each hazardous waste placed in the tank as specified by 40 CFR sections 264.1084(c)/265.1085(c). Records of the maximum organic vapor pressure determination are required. These records must include the date and time the samples were collected, the analytical method used, and results (40 CFR sections 264.1089(b)/265.1090(b)).
  4. If a tank uses Level 2 controls, the following control options are available to the owner/operator:
     • External floating roof (EFR),
     • Fixed roof with internal floating roof (IFR),
     • Closed-vent system to control device,
     • Pressure tank, or
     • Closed-vent system to an enclosed combustion device (40 CFR sections 264.1084(d)/1085(d)).

  All tanks regulated by the Subpart CC standards must be regularly inspected. Inspection procedures and requirements vary by type of tank control used. Records of all inspections, regardless of the control level, must be kept at the facility for a minimum of three years after the date of the inspection (40 CFR sections 264.1089(a) and 40 CFR 265.1090(a)).

  Owners or operators of tanks with internal or external floating roofs using Tank Level 2 controls are required to notify the Regional Administrator before conducting inspections (40 CFR sections 264.1084(e)(3)(iv), (f)(3)(iii)) and 40 CFR 265.1085(e)(3)(iv), (f)(3)(iii)). More detailed recordkeeping and inspection requirements are also required for floating roof tanks and tanks or enclosures that vent through a closed-vent system to a control device.

  Table 1. Determination of Applicable Level of Control for Tanks Containing Hazardous Waste Subject to the Subpart CC Regulations
  Tank Design Capacity	Maximum Organic Vapor Pressure of Hazardous Waste in Tank	Does Waste Stabilization Process Occur in Tank?	Applicable Level of Control
  <75 m3 (20,000 gal)	≤ 76.6 kPa (11.1 psi)	Yes	Tank Level 2 Controls
  		No	Tank Level 1 Controls
  	> 76.6 kPa	Yes	Tank Level 2 Controls
  		No	Tank Level 2 Controls
  ≥ 75 m3 (20,000 gal) and < 151 m3 (40,000 gal)	≤ 27.6 kPa (4.0 psi)	Yes	Tank Level 2 Controls
  		No	Tank Level 1 Controls
  	> 27.6 kPa	Yes	Tank Level 2 Controls
  		No	Tank Level 2 Controls
  ≥ 151 m3 (40,000 gal)	≤ 5.2 kPa (0.75 psi)	Yes	Tank Level 2 Controls
  		No	Tank Level 1 Controls
  	> 5.2 kPa	Yes	Tank Level 2 Controls
  		No	Tank Level 2 Controls

• Surface Impoundments

  Subpart CC standards applicable to surface impoundments containing hazardous wastes are found in 40 CFR sections 264.1085 and 265.1086. To control air emissions from a surface impoundment managing a hazardous waste with a volatile organic concentration greater than or equal to 500 ppmw at the point of waste origination, an owner or operator must install and operate either a floating membrane cover or a cover that is vented through a closed-vent system to a control device. The floating membrane cover must meet certain design requirements specified in the rule including a requirement that the cover be made of high-density polyethylene with a thickness no less than 2.5 mm or of an equivalent material (40 CFR sections 264.1085(c)(1)(ii)/265.1086(c)(1)(ii)). The surface impoundment cover and closure devices are to be visually inspected for defects on or before the date that the unit is subject to the Subpart CC standards and at least once a year thereafter (40 CFR section 264.1085(c)(3)(ii) and 40 CFR section 265.1086(c)(3)(i)). First efforts at repair of any defects detected on the cover or closure devices must be made within five days of detection, and repairs must be completed within 45 days of detection. A repair may be delayed more than 45 days only if it requires emptying the surface impoundment or removing it from service and no alternative capacity is available at the facility to accept the hazardous waste normally managed in the unit (40 CFR sections 264.1085(f)(2)/265.1086(f)(2)). Records of all inspections must be kept at the facility for a minimum of three years from the date of the inspection (40 CFR sections 264.1089/265.1090).

• Containers

  Subpart CC standards applicable to containers of hazardous wastes are specified in 40 CFR sections 264.1085(f)/265.1086(f)). There are three levels of air emission controls for containers based on container size, organic content, and whether the container is used in a waste stabilization process. Table 2 provides a matrix for determining the applicable control level for a container. Containers with a capacity less than or equal to 0.1 m3 (26 gallons) are exempted from the rule. Container Level 1 controls require that the hazardous waste be stored in an approved Department of Transportation (DOT) container, a container equipped with a cover and closure devices for each opening, or an open-top container with an organic-vapor-suppressing barrier (40 CFR section 264.1086(c)(1), 40 CFR section 265.1087(c)(1)). Container Level 2 controls require that the hazardous waste be stored in an approved DOT container, a container that operates with no detectable organic emissions, or a demonstrated vapor-tight container (40 CFR section 264.1086(d)(1), 40 CFR section 265.1087(d)(1)). Container Level 3 controls require that the hazardous waste be stored in a container that is either vented directly through a closed-vent system to a control device or is located inside an enclosure that is vented through a closed-vent system to a control device (40 CFR section 264.1086(e)(1), 40 CFR section 265.1087(e)(1)). Design and operating criteria are specified in the rule for the enclosure, closed-vent system, and control device.

  If a Level 1 or 2 container is not emptied within 24 hours after it is accepted at the facility, a visual inspection is required on or before the date the container is accepted. In addition, Level 1 and 2 containers must be inspected and at least once a year thereafter. Repairs of defects in such containers must be completed within 5 days or the contents of the container must be transferred to a container that complies with the Subpart CC standards (40 CFR section 264.1086(c)(4), (d)(4); 40 CFR section 265.1087(c)(4), (d)(4)).

  If a non-DOT container with a volume of 0.46 m3 (119 gallons) or larger is used with Container Level 1 controls, records of the procedure used to determine that the container is not managing hazardous waste “in light material service” must be maintained (40 CFR section 264.1086(c)(5), 40 CFR section 265.1087(c)(5)). The Subpart CC standards contain special recordkeeping and inspection requirements for Level 3 containers and their associated closed-vent systems, enclosures, and control devices (40 CFR section 264.1086(e)(4), (5); 40 CFR section 265.1087(e)(4), (5)).

  Table 2. Determination of Applicable Level of Control for Containers of Hazardous Waste Subject to the Subpart CC Regulations
  Container Design Capacity	Is the Container in Light Material Service?	Does Waste Stabilization Process Occur in Container?	Applicable Level of Control
  ≤ 0.1 m3 (26 gal)	NA	NA	Container is Exempt from Air Emission Standards
  > 0.1 m3 (26 gal) and ≤ 0.46 m3 (119 gal)	Yes	Yes	Container Level 3 Controls
  	No	No	Container Level 1 Controls
  	No	Yes	Container Level 3 Controls
  	Yes	No	Container Level 1 Controls
  > 0.46 m3 (119 gal)	Yes	Yes	Container Level 3 Controls
  	No	No	Container Level 1 Controls
  	No	Yes	Container Level 3 Controls
  	Yes	No	Container Level 2 Controls

• Miscellaneous Units

  Certain miscellaneous (Subpart X) units may also be subject to Subparts AA, BB, and CC if those requirements are necessary to protect human health and the environment (40 CFR section 264.601). The appropriate air emission controls would be implemented through the issuance or modification of a permit.

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