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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, 2019 Edition.

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©2019 McCoy and Associates, Inc. All rights reserved.

CAMUs, Temporary Units, and Staging Piles

This article discusses three units that provide flexibility when used during remediation: namely, corrective action management units, temporary units, and staging piles. Although these units are typically used only during corrective action at RCRA-permitted sites, they may also be used during other types of remedial projects.

Corrective action management units

A corrective action management unit (CAMU) is an area or unit within a facility that is used for treatment, storage, or disposal of remediation wastes. The basic purpose of these units is to encourage aggressive remediation of contaminated sites by providing a location where cleanup wastes can be managed without triggering the land disposal restrictions (LDR) or minimum technological requirements (MTRs). The CAMU provisions are codified at §§264.550–552 and 264.555. A 40-page packet of EPA guidance on CAMUs is available at

The RCRA LDR program and MTRs were established to minimize the threat to human health and the environment associated with the disposal of hazardous wastes. When EPA issued these standards, it was primarily thinking of protecting the environment from the disposal of manufacturing process wastes. However, when these rules are applied to hazardous wastes generated during cleanup of contaminated sites, they tend to be a disincentive to aggressive cleanup for the following reasons:

  • First, hazardous waste (including contaminated soil) that is excavated during a site cleanup and that will subsequently be placed in a land disposal unit, such as a landfill, is subject to the LDR program. Sometimes, this means the waste must be incinerated to meet the low LDR concentration-based standards. Burning large volumes of waste and contaminated soil is very expensive. As a result, facility owners/operators may try to avoid or delay remediation projects that involve excavation of large quantities of hazardous soil.
  • Second, land disposal units that receive hazardous waste are subject to the MTRs. This is generally interpreted to mean two liners, a leachate collection system, and ground water monitoring. Such units are more expensive to build and operate than disposal units that are not subject to MTRs. Therefore, disposal of waste in MTRs-compliant units is more expensive than disposal in non-MTRs units. As a result, facility owners/operators may try to avoid or delay remediation projects that involve excavation of large quantities of hazardous waste or soil.

In an effort to eliminate these obstacles to site remediation, EPA promulgated the CAMU regulations on February 16, 1993. [58 FR 8658] This rule gave facilities a way to manage remediation wastes without incurring the substantial costs associated with the LDR program and MTRs. Shortly thereafter, the CAMU rule was challenged in court by the Environmental Defense Fund. This organization considered the rule to be insufficiently protective of human health and the environment. (See Environmental Defense Fund v. EPA, Docket No. 93-1316, U.S. Court of Appeals for the District of Columbia Circuit.)

As a result of the litigation, significant revisions to the CAMU regulations were issued on January 22, 2002. [67 FR 2962] These revised, more-stringent requirements apply to CAMUs that are not grandfathered under the old 1993 CAMU rules. Grandfathered units are identified in §264.550(b) as CAMUs that were approved before April 22, 2002, or as units for which substantially complete permit applications had been submitted by November 20, 2000. Grandfathered CAMUs are regulated under §264.551; however, the rules for grandfathered CAMUs are not of widespread interest due to their relative scarcity. If you wanted to permit a CAMU today, the rules for new CAMUs (i.e., units that are not grandfathered) are contained in §264.552 and are discussed in the following subsections.

CAMU-eligible wastes

CAMUs can only be used to manage “CAMU-eligible wastes,” which are defined as “all solid and hazardous wastes, and all media (including ground water, surface water, soils, and sediments) and debris, that are managed for implementing cleanup. As-generated wastes (either hazardous or nonhazardous) from ongoing industrial operations at a site are not CAMU-eligible wastes.” [§264.552(a)(1)]

Containers and tanks that are excavated during cleanup (and materials they hold) are CAMU-eligible. Soil that is contaminated by releases (e.g., leachate) from operating hazardous waste units is CAMU-eligible when managed for implementing cleanup. In addition, “soil or other materials contaminated by product spills or releases from ongoing industrial processes are not considered as-generated wastes and, as such, are CAMU-eligible when managed for implementing cleanup.” [67 FR 2967] Wastes from closed or closing land-based units are CAMU-eligible; however, wastes removed from nonpermanent units (containers, tanks, waste piles) are not. [67 FR 2968]

Liquids may not be placed in CAMUs unless it will facilitate the remedy selected for the waste. [§264.552(a)(3)] EPA can prohibit the placement of waste in a CAMU if the agency believes the cleanup waste resulted from mismanaging as-generated wastes. For example, if a facility disposes hazardous waste that does not meet the applicable LDR treatment standard and subsequently has to exhume the waste, EPA could prevent the exhumed waste from being managed in a CAMU. The idea is to prevent parties from being rewarded for past noncompliance.

CAMU designations

A CAMU must be located within the contiguous property under the control of the owner/operator where the wastes to be managed in the CAMU originated. It may contain both contaminated and uncontaminated areas. The areal extent of a CAMU will be established through discussions/consultations between the owner/operator and the regulators. More than one CAMU may be designated at a facility.

An owner/operator can attain the benefits of a CAMU by voluntarily entering into the corrective action process, or by obtaining a remedial action plan (RAP—see Part 270, Subpart H). However, an owner/operator cannot unilaterally establish a CAMU—only EPA or an authorized state may do so. A Class 3 permit modification or RAP may be used to establish the CAMU and will also allow for public participation. Section 3008(h) orders can also be used to designate CAMUs. EPA expects that CAMUs may also be used as applicable or relevant and appropriate requirements (ARARs) for the remediation of CERCLA sites. [November 30, 1998; 63 FR 65880]

An example of how a CAMU could be useful during a corrective action cleanup is given in Case Study 1.

Case Study 1 Figure 1

Liners and caps

As stated previously, CAMUs are not subject to RCRA’s minimum technological requirements. However, CAMUs (other than grandfathered CAMUs) used as disposal units (i.e., the CAMUs are the final resting place of the wastes) must have liners. The liner standards are similar to those for Subtitle D landfills—a minimum composite liner consisting of a 30-mil synthetic membrane (60-mil for HDPE) on top of 2 feet of compacted soil is required. A leachate collection system capable of maintaining less than 30 cm of leachate on the liner is also required. Alternative liner designs may be approved on a case-by-case basis. [§264.552(e)(3)]

CAMUs used for disposal must be closed with a cap that meets essentially the same performance standards as currently required for closed hazardous waste landfills.

Ground water monitoring is required whenever the CAMU contains a disposal unit. EPA must be notified of any ground water contamination originating from the CAMU, and corrective action requirements would apply. Treatment- and storage-only CAMUs do not need ground water monitoring.

Treatment requirements

The LDR program in Part 268 does not apply to wastes placed into or within a CAMU. [§264.552(a)(4)] However, before wastes may be disposed in a CAMU (other than a grandfathered CAMU), “principal hazardous constituents” (PHCs) must be treated to meet standards that are similar to the LDR alternative soil standards in §268.49. (Wastes may be stored in the CAMU without being treated first.)

PHCs include constituents that meet two criteria. First, they must otherwise be subject to treatment under the LDR program for as-generated wastes. Second, PHCs must pose higher risks than site-specific cleanup levels. In general, these are constituents that, if carcinogens, exceed a 10–3 risk level, or if noncarcinogens, exceed the reference dose by an order of magnitude.

Once identified, PHCs in CAMU-eligible wastes must be treated to reduce their concentrations by 90% but do not have to be treated to below 10 times the UTS (universal treatment standards) levels in §268.48. PHCs on debris must be treated to this same standard or to the LDR alternative debris standards in §268.45.

Case-by-case “adjustment factors” may be applied that could increase or decrease the amount of treatment required. One adjustment factor is “views of the affected local community.” The treatment requirements for CAMU-eligible wastes are codified in §264.552(e)(4).

Treatment/storage CAMUs

CAMUs used solely to treat or store wastes are not subject to the requirements for liners, caps, and treatment discussed in the preceding sections. Instead, they are subject to essentially the same performance standards as staging piles that are discussed later in this article. However, if wastes remain in these units for more than 2.5 years, liners and ground water monitoring must be provided. [67 FR 2995–6]

Offsite disposal of CAMU-eligible wastes

Under §264.555, CAMU-eligible wastes may be disposed at an offsite hazardous waste landfill that meets Part 264, Subpart N landfill standards (e.g., the landfill must have a double synthetic liner and leachate collection system). PHCs in the cleanup waste must meet treatment standards established by regulators in the originating state. The same treatment standards that are available for onsite CAMU disposal apply; that is, PHC concentrations must be reduced by 90% but treatment to less than 10 times UTS is not required. Some of the adjustment factors that can be used to increase or decrease the amount of treatment required when wastes are disposed in an onsite CAMU are not available when the wastes are disposed offsite.

The receiving landfill must have a RCRA permit (i.e., interim status landfills may not receive CAMU-eligible wastes). The landfill’s permit must specifically allow receipt of CAMU-eligible wastes; Class 2 permit modifications could be used for this purpose. Once the permit modification is approved, the landfill could potentially accept any CAMU-eligible waste approved for offsite disposal by regulators overseeing remediation sites.

Before an offsite landfill can dispose waste from a specific remediation site, three criteria must be met: 1) the public must be notified of the landfill facility’s intent to receive waste from a particular cleanup, 2) the public has 15 days to provide comments to the landfill’s regulators, and 3) the landfill’s regulators have up to 60 days to approve the disposal. Disposal cannot occur without notification from EPA or the state that they do not object to placement of the CAMU-eligible wastes.

State authorization issues

In states that are not authorized to administer the corrective action program, EPA administers corrective action and implements the CAMU regulations described in this section. States that are authorized to administer corrective action were not required to adopt the CAMU regulations promulgated in 1993, because they were less stringent than the pre-existing rules for remediation waste management. However, states that are authorized to administer the CAMU regs were also required to adopt the more stringent CAMU regulations promulgated by EPA on January 22, 2002. In order to prevent a slowdown in the state approval of CAMUs, states that were CAMU-authorized in 2002 were granted “interim authorization by rule” to administer the new standards.

Temporary units

Temporary units (TUs) are tanks or container storage areas used to store or treat hazardous remediation wastes during site cleanups. A TU must be located within the contiguous property under the control of the owner/operator where the wastes to be managed originated. The TU regulations are in §264.553.

EPA and states may authorize the use of TUs and replace the otherwise applicable Parts 264 and 265 design, operating, or closure standards for hazardous waste tanks or containers with alternative standards that can be determined on a site-specific basis. The alternative standards must protect human health and the environment. The idea is to provide more flexibility to regulators overseeing remediation projects. The regulators may authorize the use of TUs in a Class 2 permit modification, a RCRA Section 3008(h) order, a RAP, or a CERCLA record of decision (ROD).

TUs may also be used for activities that are not part of a selected remedy, interim measure, or site stabilization activity. For example, prior to selecting a remedy, large quantities of investigation-derived wastes may be generated during a facility’s RCRA facility investigation. A TU could be used to store or treat such waste. However, the owner/operator would have to seek a Class 2 permit modification or similar type of approval to use the TU.

Wastes may be stored/treated in TUs for only one year; however, a one-year extension is available. At the end of the unit’s approved life, management of remediation waste in the unit must cease and the unit must be closed. Alternatively, the unit could be retrofitted to meet Part 264/265 standards, as addressed through a permit modification. A 40-page packet of EPA guidance on CAMUs and TUs is available at

Staging piles

EPA developed the concept of a staging pile to solve a particular problem. To explain the problem, we begin with some definitions from §260.10:

  • “Remediation waste” means all solid and hazardous wastes, and all media (including ground water, surface water, soils, and sediments) and debris, that are managed for implementing cleanup.”
  • A waste “pile” is defined as “any noncontainerized accumulation of solid, nonflowing hazardous waste that is used for treatment or storage and that is not a containment building.”

Waste piles are considered to be land disposal units and, therefore, must be equipped with liners, leachate collection systems, and ground water monitoring systems (i.e., MTRs), as specified in Parts 264/265, Subpart L. Furthermore, hazardous waste must meet LDR treatment standards prior to placement in a waste pile. Sometimes people excavate large quantities of hazardous remediation waste during a cleanup project. The problem is that if hazardous remediation waste is placed in a pile, in general, the pile is a waste pile subject to the aforementioned requirements. This would make it very difficult to excavate remediation waste and store or treat it in a pile. One option would be to use a CAMU for this purpose, but obtaining approval for a CAMU can be very difficult.

EPA’s solution to the problem described above was to develop a new type of remediation waste management unit called a “staging pile.” A staging pile is defined as “an accumulation of solid, nonflowing remediation waste that is not a containment building and that is used only during remedial operations for temporary storage at a facility.” [§260.10] Keep in mind that a staging pile cannot be used to manage hazardous wastes from ongoing industrial processes.

Remediation waste may be placed in a staging pile without triggering the LDR program or MTRs for hazardous waste piles. These units must be located within the contiguous property under the control of the owner/operator where the wastes to be temporarily stored originated. The staging pile regulations are in §264.554.

These piles are intended to “facilitate short-term storage of remediation wastes so that sufficient volumes can be accumulated for shipment to an offsite treatment facility or for efficient onsite treatment.” [November 30, 1998; 63 FR 65909] Staging piles can be used to store contaminated soil temporarily while decisions on the final remedy for site cleanup are being finalized. In addition, staging piles may be used for physical operations intended to prepare wastes for subsequent treatment (e.g., mixing, sizing, blending, and other similar physical operations). [§264.554(a)(1)]

A two-year time limit (with a possible 180-day extension) applies to staging piles from the time the owner/operator first places remediation waste in the pile. If the remediation waste is expected to need storage for longer than 2 years, a CAMU is more appropriate. Storage of hazardous waste in approved staging piles is exempt from the LDR storage prohibition of §268.50.

Staging piles provide an alternative to seeking a CAMU. For example, where a site has noncontiguous areas of contaminated soil, a staging pile in one of those areas may be used to temporarily store waste from the other contaminated areas prior to further management. [63 FR 65920]

Staging piles are not self-implementing; that is, the owner/operator of a facility undergoing remedial operations must get EPA’s or the state’s approval to use such a pile. A Class 2 permit modification or RAP is required for a permitted TSD facility, while an interim status facility or generator must have the staging pile designated in a RAP, closure plan, or order. Such approval will also include design standards and operating practices to meet the following performance standard: the staging pile must prevent or minimize releases and cross-media transfers of hazardous wastes and constituents into the environment (e.g., through the use of liners, covers, run-off/run-on controls, ground water and/or air monitoring, and inspections). [§264.554(d)(1)(ii)]

Special requirements apply for ignitable, reactive, or incompatible wastes placed in staging piles. EPA expects that staging piles may be used as ARARs for the remediation of CERCLA sites. [63 FR 65932]

Staging piles must be closed within 180 days after their operating term expires. There are two sets of closure standards: 1) if the pile is located in an uncontaminated area, it must be clean closed; 2) if the staging pile is located in a previously contaminated area, the final cleanup of the contaminated subsoil may be coordinated with the overall site remedy. [§264.554(j–k)]

An example of using a staging pile during facility cleanup is given in Case Study 2.

Case Study 1 Figure 1


Topic: Corrective Action

©2019 McCoy and Associates, Inc. All rights reserved.

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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.