Compliance Corner.


In the United States, hazardous wastes are subject to regulations mandated by the Resource Conservation and Recovery Act (RCRA). Every month, we provide clear, in-depth guidance on a different aspect of the RCRA regulations. The information presented here is an excerpt from McCoy’s RCRA Unraveled, 2024 Edition.

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Complying with Subpart BB

The preceding discussion serves to identify equipment subject to Subpart BB. Once such equipment is identified, the next step is to determine how to comply with Subpart BB fugitive emission standards. If a piece of equipment is subject to Subpart BB, fugitive emissions are controlled in several ways:

  1. Design standards are imposed in limited circumstances. For example, pumps equipped with a dual mechanical seal system that includes a barrier-fluid system are subject to reduced monitoring requirements. [§§264/265.1052(d)]
  2. Inspection requirements are frequently imposed. For example, many pumps must be inspected weekly for indications that liquids are dripping from the seal. [§§264/265.1052(a)(2)]
  3. Monitoring requirements are often obligatory. For example, many valves must be monitored monthly to detect leaks. [§§264/265.1057(a)]
  4. Unexpected leak detection requires action. In some cases, equipment doesn’t have to be inspected or monitored on a routine basis; however, if someone notices that the equipment is leaking, it must be monitored and fixed. [§§264/265.1058(a)]

Light liquid service

Because “light” liquids are more likely to produce fugitive organic emissions, equipment handling these types of wastes is subject to more stringent design/inspection/monitoring standards. “In light liquid service means that the piece of equipment contains or contacts a waste stream where the vapor pressure of one or more of the organic components in the stream is greater than 0.3 kilopascals (kPa) at 20°C, the total concentration of the pure organic components having a vapor pressure greater than 0.3 kilopascals (kPa) at 20°C is equal to or greater than 20 percent by weight, and the fluid is a liquid at operating conditions.” [§§264/265.1031] EPA noted in guidance that the definition applies only to the organic components of the waste stream—not to nonorganic constituents that meet the vapor pressure criteria (e.g., water). [December 8, 1997; 62 FR 64639]

If the equipment contains or contacts a hazardous waste stream that meets the definition above, it is “in light liquid service.” If the waste stream doesn’t meet all three criteria in the definition, the equipment is “in heavy liquid service.”

To help people make the light versus heavy liquid service determination, EPA included guidance in EPA/450/3-89/021. According to this document, each organic compound in the waste, its concentration, and its vapor pressure must be known. A complete analysis (e.g., gas chromatography/mass spectroscopy) or engineering estimate should be used to determine the waste stream composition. Vapor pressures for many constituents at 20°C are available in chemical literature. If the vapor pressure for a particular component is not available, the pure component can be tested using ASTM Method D2879 to determine the vapor pressure.

The LDAR program

In general, Subpart BB is an LDAR program. Inspection and monitoring requirements are imposed for each type of equipment meeting the Subpart BB applicability requirements. Such inspections and monitoring are designed to detect leaks; once a leak is detected, repair must be initiated within 5 days and completed as soon as practicable, not to exceed 15 days.

Table 1 summarizes the inspection and monitoring requirements for the various types of Subpart BB equipment. As noted in the table, the inspection/monitoring options for valves are the most complex. Where the table is not self-explanatory, references are given to section numbers in Parts 264/265 where the details may be found.

Table 1

Closed-vent systems connected to a control device may be used to control emissions from leaking equipment. This would essentially consist of a hood over/around the equipment to capture any emissions. Sections 264/265.1060 impose standards on the closed-vent systems and control devices that are taken from Subpart AA.

Identification of Subpart BB-regulated equipment

Sections 264.1050(d)/265.1050(c) require each piece of equipment subject to Subpart BB be marked so it can be distinguished readily from other pieces of equipment at the plant not subject to LDAR requirements. The most common method of complying with this requirement is to tag each piece of Subpart BB-regulated equipment. The regulations seem to imply tagging is required, but conversations with industry professionals and regulators indicate that the regulatory language does not necessarily require physical tagging or marking, and that a plant site plan or diagram may meet the intent of the §§264.1050(d)/265.1050(c) marking requirements. However, an authorized state agency may have a more-stringent interpretation.

There is an almost identically worded requirement for marking equipment in the CAA regulations for equipment leaks (fugitive emission sources). [§61.242-1(d)] Written guidance from EPA Region 4 states an alternative marking system of assigning each flange or other connector an identification number corresponding to the nearest piece of physically tagged equipment and recording those numbers in a log would be acceptable. This guidance is available at by searching for NR89 in the Control Number field.

In “Leak Detection and Repair—A Best Practices Guide,” available at, EPA says the best practice is as follows: Physically tag each regulated equipment component with a unique ID number. Write the component ID number on piping and instrumentation diagrams. Institute an electronic data management system for LDAR data and records, possibly using bar coding equipment. And, finally, periodically conduct field audits to ensure lists and diagrams accurately represent equipment installed in the plant.

EPA/530/R-19/006 gives the following final thought on this topic: “The requirements in 40 CFR 264.1064(b)(1), including assigning and recording an individual ID number to each piece of equipment, as well as developing/maintaining a list of the equipment ID numbers with a plot diagram illustrating the location of the equipment, is an effective means to easily distinguish regulated equipment from other pieces of equipment.”

Typical Subpart BB violations

According to EPA/300/F-20001, LDAR monitoring violations arise when instrument (i.e., photo or flame ionization detector) calibration is faulty or incomplete, or the required monitoring is not performed correctly, accurately, or with the proper frequency as required in the regulations. Additionally, EPA inspectors have frequently found noncompliance when pressure-relief valves are stuck open, allowing a continuous release of emissions from hazardous waste into the air.

Recordkeeping, reporting, and training

EPA and state inspectors rely primarily on their review of a facility’s records to determine if the facility is complying with Subpart BB. The extensive recordkeeping requirements for Subpart BB are codified at §§264/265.1064. When conducting compliance inspections, EPA inspectors thoroughly review records to ensure the facility is meeting requirements for equipment identification, location, tagging, leak detection monitoring, calibration of instrumentation, and leak repair time frames. [EPA/300/F-20001] Many facilities choose to comply with these requirements and their CAA LDAR requirements via the service of a contractor that conducts the inspections and monitoring and also maintains all of the associated documentation.

For permitted facilities only, §264.1065 imposes reporting requirements. These regulations require owners/operators to file a report every six months identifying leaking valves, pumps, and compressors that were not repaired within 15 days. Where control devices are used to manage fugitive emissions, instances of control device failures/excursions exceeding 24 hours in duration must also be reported. If all leaking valves, pumps, and compressors are repaired within 15 days and all control devices function properly, no semiannual report is required.

According to §§264/265.16 and 262.17(a)(7), facility personnel must be trained to perform their duties in a way that ensures the facility’s compliance with Parts 264/265 and 262. This includes people responsible for complying with the Subpart BB air emission standards. For example, an LDAR monitoring technician must be trained so they can identify the equipment that must be monitored for leaks and can conduct the monitoring as prescribed by the regulations. When Method 21 monitoring is required, the technician must be trained how to do this properly. Chapter 9 in EPA/450/3-89/021 discusses training for Subparts AA and BB compliance.

Common problems and best practices

EPA found significant noncompliance with LDAR regulations and, more specifically, noncompliance with Method 21 requirements. To improve compliance, the agency published “Leak Detection and Repair—A Best Practices Guide,” cited above. The guide identifies common problems, many of which involve not properly following Method 21, and identifies best practices for LDAR programs.


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Considerable care has been exercised in preparing this document; however, McCoy and Associates, Inc. makes no representation, warranty, or guarantee in connection with the publication of this information. McCoy and Associates, Inc. expressly disclaims any liability or responsibility for loss or damage resulting from its use or for the violation of any federal, state, or municipal law or regulation with which this information may conflict. McCoy and Associates, Inc. does not undertake any duty to ensure the continued accuracy of this information.

This document addresses issues of a general nature related to the federal RCRA regulations. Persons evaluating specific circumstances dealing with the RCRA regulations should review state and local laws and regulations, which may be more stringent than federal requirements. In addition, the assistance of a qualified professional should be enlisted to address any site-specific circumstances.