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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, 2018 Edition.

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©2018 McCoy and Associates, Inc. All rights reserved.

HW Tank Secondary Containment and Release Detection Requirements

Sections 264/265.193 require permitted and interim status TSD facilities and large quantity generators to install secondary containment and release detection for their hazardous waste tanks. While this requirement is a cornerstone of EPA’s goal of preventing hazardous waste releases to the environment, it is also one of the most expensive provisions that facilities must implement as part of their RCRA compliance efforts for hazardous waste tanks.


As noted in Table 1, secondary containment/release detection must be provided for all existing and new tanks and their associated ancillary equipment at the following locations: 1) permitted TSD facilities, 2) interim status TSD facilities, and 3) large quantity generators. Notably absent from this list is 180/270-day accumulation tanks operated by small quantity generators. Table 1 Small quantity generators are not required to provide secondary containment for their tanks except under very limited circumstances. [§262.16(b)(3)(ii)(C)] Also, secondary containment is not required for a hazardous waste tank at any type of facility if the tank system is 1) used to store or treat a hazardous waste that contains no free liquids, and 2) located inside a building with an impermeable floor. [§§264/265.190(a)]

Avoiding an endless loop

One common way for a facility to provide secondary containment for a Subpart J regulated tank is to install a concrete pad and walls under and around the tank. However, such a concrete structure meets the definition of “tank” in §260.10, and so itself is subject to Subpart J standards, including the requirement for secondary containment. Obviously, providing additional containment for a secondary containment structure was not EPA’s intent, and so, in §§264/265.190(b), the agency notes that any tank system (including a sump) that serves as part of a secondary containment system need not be provided with another secondary containment system.

Technical details

According to §§264/265.193(b), secondary containment systems must be:

“(1) Designed, installed, and operated to prevent any migration of wastes or accumulated liquid out of the system to the soil, ground water, or surface water at any time during the use of the tank system; and

“(2) Capable of detecting and collecting releases and accumulated liquids until the collected material is removed.”

Toward these goals, secondary containment systems must meet the following general technical requirements. They must be:

  • Constructed of, or lined with, materials that 1) are compatible with the hazardous waste(s) that may enter the system; and 2) have sufficient strength and thickness to prevent failure due to the weight of the waste(s), physical contact with the waste, external hydrogeological forces, climatic conditions, and/or the stresses of day-to-day operations;
  • Placed on a foundation or base capable of supporting the containment system; resisting pressure gradients above and below the system; and preventing failures due to settlement, compression, or uplift; and
  • Sloped or otherwise operated to drain and remove liquids resulting from leaks, spills, or precipitation. EPA noted that liners should have a minimum slope of 1/4 inch per linear foot to a dry well or sump to allow liquids to drain for detection and removal. [EPA/530/SW-86/044]

EPA believes that most secondary containment systems for tanks will consist of one of three primary system designs: external liners (see Figure 1), vaults (see Figure 2), or double-walled tanks. Specific design requirements for these three systems are listed in Table 2.

Figure 1 Figure 2 Table 2

More on required containment system capacity

As noted in Table 2, external liner systems and vaults must be sized for the largest hazardous waste tank they contain plus 24 hours of rainfall from a 25-year storm (e.g., 10 inches in Houston, 4.5 inches in Chicago). In contrast, a specific capacity standard is not given for double-walled tanks. EPA believes the inherent design of such systems makes such a requirement unnecessary. [RO 13162]

Some facilities have severe space constraints, such that building an external liner of sufficient capacity around their hazardous waste tank would be difficult. One such facility asked EPA if they could alternatively use a pump system to remove accumulated liquids in combination with a smaller-volume containment structure to satisfy the capacity requirement. The agency was skeptical in its reply, noting that mechanical breakdowns, power failures, and other problems greatly reduce the reliability of operational controls, such as pumps, versus passive systems such as concrete walls. However, EPA suggested that such systems might work in certain situations, if the facility can demonstrate to the state or EPA region that the operational system does not increase the risk of a release of hazardous waste into the environment when compared to using a passive secondary containment barrier. [RO 13341]

The agency also notes that secondary containment systems that serve multiple tanks need be sized only for the largest contained tank that is in hazardous waste service. As is implied, this means that there are no restrictions against placing hazardous waste and other types of tanks (e.g., petroleum storage tanks) in the same containment area. Where this is the case, however, the entire area must meet applicable Subpart J requirements. [RO 12965, 13336]

Containment structures must be impermeable

EPA believes that concrete external liner and vault structures used as secondary containment systems will require an impermeable coating or lining (e.g., an epoxy coating, high-density polyethylene, stainless steel plate) to prevent migration of waste into the concrete. Although this requirement is specified only for vaults in the regulations, the agency didn’t intend to limit such a coating or lining requirement to concrete vaults. The coating or lining must entirely and uniformly cover the surface of the concrete structure that could come into contact with released waste. [EPA/530/SW-88/004, 53 FR 34084, RO 13152, 14395]

The coating or lining must be compatible with the stored hazardous waste. [RO 12953] A concrete secondary containment structure to which an impermeable chemical-resistant coating or lining is applied must be certified by a qualified professional engineer. [RO 13250]

Any wear, cracks, etc. in the concrete or coating or lining must be repaired promptly. [RO 13152] We have encountered situations where maintenance personnel scuff or scrape off the epoxy coating from a secondary containment structure, resulting in nonimpermeable containment and notice of violation.

Can a building serve as secondary containment for a tank system located inside it?

Yes. A building could function as secondary containment for a tank, providing the structure meets the requirements of §§264/265.193(b–c). [July 14, 1986; 51 FR 25452, RO 13633, 14119, 14463, 14632] “In cases involving buildings serving as secondary containment, authorized states necessarily have the ultimate authority to make the determination that secondary containment requirements are met (taking into account all relevant site-specific considerations).” [April 4, 2006; 71 FR 16880]


Although usually a more expensive proposition than for their aboveground counterparts, underground storage tanks (USTs) that store hazardous waste must also be provided with secondary containment. [RO 12774] Normally, this would take the form of either a vault or a double-walled tank system.

Ancillary equipment

Because ancillary equipment is considered part of a tank system, it is subject to Subpart J requirements including secondary containment that meets the general design conditions listed above. Pumps, valves, flanges, fittings, etc. that are associated with a hazardous waste tank require secondary containment. Such secondary containment usually consists of jacketing, double-walled piping, the process building itself [51 FR 25452, RO 14632], or lined trenches underneath the equipment that flow to a regulated unit. However, the following ancillary equipment does not require secondary containment:

  • Aboveground piping that is visually inspected for leaks on a daily basis is exempt from secondary containment. In addition, pipe runs that have all welded fittings and that are inspected daily do not require secondary containment. [§§264/265.193(f)(1–2), RO 12953, 12998] Threaded fittings on pipe runs outside of the tank’s secondary containment structure require their own secondary containment, because these fittings are where EPA thinks most leakage occurs. A flange is considered “welded” if the pipe-to-flange joint is welded (as opposed to threaded)—the flange faces at the gasket do not have to be seal welded. Therefore, weld-neck, lap-joint, socket-weld, and slip-on flanges are all considered welded flanges. [September 2, 1988; 53 FR 34081, RO 12953, 12973, 13221] For plastic piping, solvent-cemented and heat-fusion connections would be considered welded and would not require secondary containment if inspected daily; mechanical joints, however, would need secondary containment. [53 FR 34082, RO 12953, 13221] Secondary containment is required for soldered and brazed joints, compression fittings, and flared fittings for hazardous waste tubing.
  • Sealless or magnetic-coupling pumps and sealless valves that are visually inspected for leaks on a daily basis do not require secondary containment. [§§264/265.193(f)(3)] Packing-type pump seals require secondary containment. [RO 12973] EPA notes that valves that use a metal bellows to seal the valve stem, and essentially any other design that achieves containment within the valve body, would qualify as sealless. [RO 12720, 13047] This exemption from secondary containment applies only to the seals; the connections of this equipment to the pipeline must be provided with secondary containment unless they are welded. [RO 12720]
  • Secondary containment is not required for pressurized aboveground piping systems with automatic shut-off devices (e.g., excess flow check valves, flow-metering shutdown devices, shut-off devices actuated on a loss of pressure) that are visually inspected for leaks on a daily basis. [§§264/265.193(f)(4)] This provision applies even if welded fittings, sealless or magnetic-coupling pumps, and/or sealless valves are not used. [53 FR 34084, RO 13005] EPA has not assigned a specific numerical value to distinguish pressurized from nonpressurized piping. The agency generally considers only that piping located on the discharge side of pumps to be “pressurized.” Although technically it is under pressure due to static head pressure, piping connected to the bottom of tanks is not considered pressurized. [RO 13244]
  • Ancillary equipment associated with non-Subpart J regulated units, such as surface impoundments or exempt tanks, is not subject to secondary containment requirements. [RO 13126]

The agency notes in guidance that secondary containment requirements do apply to underground hazardous waste piping, stating its reasoning as follows:

“EPA believes that secondary containment with leak detection is an absolute necessity. Not only is underground piping more prone to failure due to corrosion and other soil-related stresses, than is aboveground piping, but it is also impossible to visually observe any impending or actual failure of the piping system, particularly for less than catastrophic releases.” [RO 12973]

Secondary containment systems for ancillary equipment must be capable of “collecting releases and accumulated liquids until the collected material is removed.” [§§264/265.193(b)(2)] Where secondary containment systems serve tank system piping in transport vessel loading stations, required secondary containment capacity would be based on the largest projected spill that could occur prior to cleanup responses, plus incidental precipitation. Such a system might consist of a concrete pad with 6-in. curbing. [Memo from Bruce Weddle, EPA Headquarters to Stanley Siegel, EPA Region II, March 17, 1988]

A facility wants to use a trench that normally has nonhazardous wastewater flowing through it as secondary containment for a hazardous waste pipeline. The capacity of the trench will hold both the nonhazardous wastewater flow and the contents of the pipe should it burst. Can the trench be used for this purpose?

No. Secondary containment must normally be dry in order to detect a release from the hazardous waste line. [RO 13221]

Release detection

Besides the general design requirements noted above, secondary containment systems must also be provided with release detection such that a failure of the primary containment system will be detected within 24 hours of its occurrence, or at the earliest practical time. [§§264/265.193(c)(3)] Once detected, the facility must ensure that spilled or leaked waste (and precipitation) is removed from the secondary containment system within 24 hours, or “in as timely a manner as is possible to prevent harm to human health and the environment.” [§§264/265.193(c)(4)]

Release detection systems include wire grids, observation wells, and U-tubes. The types of leak sensors used in these systems include thermal conductivity sensors, electrical resistivity sensors, and vapor detectors. [EPA/530/K-05/018, EPA/530/SW-86/044] Significant technical guidance on these systems is provided in EPA/530/SW-86/044.

We have seen a number of tank systems with built-in sumps in the bottom of the secondary containment structures (see Figure 1). These sumps are provided with liquid level instrumentation that triggers an alarm to appropriate facility personnel if liquid is detected and/or they are inspected every day for signs of liquid. A drain line is often installed in the sump, allowing accumulated liquids to be withdrawn from the containment area. Should a valve be installed in that drain line? The agency noted in EPA/530/SW-86/044 that containment systems should be:

“equipped with manual release valves, siphons, or pumps to permit removal of collected liquids. Valves should be chained and locked in a closed position when not in use.… If the collected material is hazardous…it must be managed in accordance with all applicable requirements of Parts 262 through 265 of RCRA….”

Except for double-walled tanks, daily visual inspections may be conducted as an alternative means of satisfying the release detection requirements for secondary containment systems, subject to the restrictions discussed below. Of course, the tank and ancillary equipment must be aboveground and accessible for such inspections to be an acceptable alternative. Where, for example, a tank is resting directly on a concrete pad, the owner/operator must demonstrate (to his/her RCRA authority) that visual inspections would reliably indicate leakage from the bottom of the tank within 24 hours of its occurrence. To make such a case, the concrete pad would have to be impermeable and free of cracks (e.g., lined or coated) and sloped or otherwise designed to facilitate the flow of released waste from under the tanks (e.g., equipped with ridges or grooves). Another possibility is raising the tank above the pad onto structural support steel; again, a daily visual inspection would fulfill the release detection requirement. [April 4, 2006; 71 FR 16879, RO 12701, 12921, 13173, 13195]

Also, note that where daily visual inspections are being used as a means of leak detection, the inspections must be conducted every day that the subject tank contains hazardous waste, even if the manufacturing system that generates waste and sends it to the tank is not in operation every day. [RO 13063] (This inspection requirement, which is meeting the release detection provisions, is independent of the general tank inspection requirements in §§264/265.195.)

Secondary containment system requirements for double-walled tanks specify built-in, continuous leak detection. This is specified because it is a standard design feature of these types of tanks. [RO 12701]

Release detection is also required for ancillary equipment. Leak-detection sensors along the lengths of piping enable an owner/operator to detect even small leaks within a piping system. Sensors used in these applications are the same as those described above.

Finally, note that release detection systems monitor for leaks from primary containment devices (i.e., the tank and its ancillary equipment) into the secondary containment structure. Leak detection is not required outside of the secondary containment system in order to detect failure of that equipment. [September 2, 1988; 53 FR 34084]

Responses to releases

In order to minimize effects on human health and the environment, EPA has spelled out a number of mandatory steps owners/operators must take when leaks or spills occur from tank systems, or when tanks are found to be unfit for use. These steps are as follows [§§264/265.196]:

  • The flow of hazardous waste into the tank or secondary containment system must be stopped immediately and the system must be inspected to determine the cause of the release.
  • If the release was from a tank system, enough waste material must be removed from the tank system within 24 hours after release detection, or as soon as practical, to prevent further releases and facilitate inspection and repairs.
  • Where released material was captured in a secondary containment system, the waste must be removed from the containment system within 24 hours, or in as timely a manner as possible.
  • An immediate visual inspection of the leak or spill must be made so that steps may be taken to prevent or minimize migration of material to soil and/or surface water, and so that visibly contaminated soil and/or surface water may be removed and disposed.
  • Tanks, ancillary equipment, and secondary containment systems must be repaired prior to being placed back into service. Where such repairs are major, they must be certified by a qualified professional engineer. If needed repairs cannot be made, the tank system must be closed per the terms of §§264/265.197.
  • If the source of the leak or spill is a component of a tank system currently without secondary containment, that component must be provided with secondary containment before being placed back into service (unless the component is aboveground and can be inspected daily for leaks).


If any leak or spill enters the environment, the facility owner/operator must verbally notify the state or EPA within 24 hours of its detection. If the National Response Center has been notified pursuant to CERCLA requirements in 40 CFR Part 302, that call satisfies this reporting requirement. A written report summarizing the circumstances of the release and its subsequent investigation (e.g., cause, extent of contamination, corrective action, etc.) must subsequently be sent to the state or EPA within 30 days of detecting the release. Note that reporting is not required where no more than one pound of waste was released and the released material was immediately contained and cleaned up.

Releases completely contained within secondary containment systems are not reportable since they never entered the environment. [EPA/530/SW-87/012]

Implementation timing for secondary containment

Sections 264/265.193(a) list the following deadlines by which secondary containment must be installed on new and existing hazardous waste tank systems:

  1. Prior to placing new tank systems into hazardous waste service; and
  2. For existing tank systems that store or treat material that becomes a hazardous waste (i.e., as a result of a newly identified or listed hazardous waste), within 2 years of the new hazardous waste identification or listing, or when the tank system has reached an age of 15 years, whichever is later.

In the July 14, 1986 final rule that implemented the secondary containment requirement for hazardous waste tanks [51 FR 25422], EPA noted that 15 years is the approximate median time to failure for underground steel tanks the agency studied in developing the rule. Thus, this is the trigger age for existing tanks to install secondary containment.

In evaluating equipment in terms of the 15-year trigger, the agency notes that it is the age of the tank itself, not the length of time it has been in hazardous waste service that is pertinent. Thus, a 14-year old tank in hazardous waste service for just three years would require secondary containment within one year. [RO 13191] For ancillary equipment in pipe runs, the age of the piping, valves, fittings, etc. should be used against the trigger date, rather than the age of the hazardous waste tank with which the piping is associated. This is especially important where piping was completely replaced after the installation date of its associated tank. [RO 12702]

A tank system installed in July of 1978 was used to store a previously nonhazardous material that was listed as a hazardous waste on May 15, 2001. When is secondary containment required?

The unit is considered an existing hazardous waste tank. Although the tank system was already more than 15 years old as of May 15, 2001, the owner/operator has two years from that date to install secondary containment. The deadline, therefore, was May 15, 2003.

Interim measures for existing tanks without secondary containment

Tank systems subject to secondary containment requirements, but which have not yet been so equipped, are subject to several interim requirements:

  • Aboveground and enterable USTs must be leak tested annually or be subject to an agency-approved integrity assessment prepared by a professional engineer. If the latter assessment is conducted, it must be adequate to detect cracks, leaks, and corrosion or other conditions that might lead to cracks and leaks. The frequency of the integrity assessment must be based on the age of the system, material of construction of the tank and its ancillary equipment, characteristics of the wastes stored or treated in the system, type of corrosion protection in use, and rate of corrosion or erosion noted in previous inspections.
  • Nonenterable USTs must be leak tested annually per the terms of §§264/265.191(b)(5).
  • Ancillary equipment must be leak tested or have their integrity checked annually via an agency-approved method.

Owners/operators of certain hazardous waste storage tanks that do not have secondary containment must conduct leak tests “at least annually” until secondary containment is provided. [§§264/265.193(i)(1)] What is the definition of “annually”?

EPA interprets this term to mean once every 12 months, as opposed to once every calendar year. [RO 14168] For example, if the owner/operator conducted a leak test on August 1 of one year, the test would have to be conducted by August 1 of the second year. If the owner/operator tested the tank on July 1 of the second year, the next test would need to be performed on or before July 1 of the third year.

Variances may be requested

Owners/operators of tank systems may request a variance from EPA or the state from the secondary containment requirements. Such a variance must propose an alternative design and/or operating scheme that, in conjunction with site-specific characteristics, will provide similar spill and leak containment and control. Without going into too much detail [see §§264/265.193(g) for specifics], the facility must petition the agency 1) at least 24 months prior to the date secondary containment is required for existing systems, or 2) at least 30 days before entering into a contract to install a new tank system. The agency will weigh the petition and an associated demonstration of the alternative approach, along with site-specific factors before issuing a decision whether to grant the variance. [RO 12754] The factors evaluated when a variance is proposed using a process building for secondary containment are summarized in RO 14632. Significant guidance on obtaining either a technology-based or risk-based variance from the secondary containment requirements is contained in EPA/530/SW-87/002A or B, February 1987, available from by downloading the reports 530SW87002A or 530SW87002B, respectively.


Topic: Lab Packs

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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.