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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, 2021 Edition.

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Are Sumps Tanks?

Yes—if they pass the so-called parking lot test. The key concept of the test is a tank must “provide structural support” and “contain an accumulation of hazardous waste,” both of which are included in the definition of “tank.” A look at EPA’s definition of the term “sump” notes that:

Sump means any pit or reservoir that meets the definition of tank and those troughs/trenches connected to it that serve to collect hazardous waste for transport to hazardous waste storage, treatment, or disposal facilities; except that as used in the landfill, surface impoundment, and waste pile rules, ‘sump’ means any lined pit or reservoir that serves to collect liquids drained from a leachate collection and removal system or leak detection system for subsequent removal from the system.” [§260.10]

There are several parts to this definition, but the primary issue is sumps that pass the parking lot test are regulated exactly like tanks under RCRA Subtitle C (with a couple of exceptions as noted below). Comprehensive guidance on determining the integrity of concrete sumps is given in EPA/530/R-93/005, available from by downloading the report numbered 530R93005. Based on this definition and agency guidance, we have concluded there are three types of sumps from a RCRA perspective (and each one is subject to different regulatory requirements):

  1. Temporary sumps,
  2. Secondary containment sumps, and
  3. Primary containment sumps.

Temporary sumps

Temporary sumps are regulated the same as temporary tanks, as an immediate response unit. Hazardous waste is stored in temporary sumps only in response to a leak, spill, or other temporary, unplanned occurrence. The immediate response exemption applies to these “dry” sumps and, therefore, RCRA permitting and Subpart J tank standards do not. “A sump that may be used to collect hazardous waste in the event of a spill, whether accidental or intentional, and that is not designed to serve as a secondary containment structure for a tank storing hazardous waste, is generally exempt from regulatory and permitting requirements so long as it is used to contain hazardous waste only as an immediate response to such a spill.” [September 2, 1988; 53 FR 34085]

A temporary sump is not a unit designed to serve as secondary containment to a primary hazardous waste containment vessel (e.g., a storage tank) or its associated ancillary equipment. Such a unit is a secondary containment sump, as described below.

Secondary containment sumps

Sometimes, sumps aren’t the primary vessel used to manage hazardous waste but are utilized as a secondary containment structure. These units are specifically designed to contain spills from a primary containment vessel (or its associated ancillary equipment). Such secondary containment sumps are not immediate response units and, because they meet the definition of a tank, are subject to Subpart J tank standards (e.g., they must be impermeable, they must be inspected). However, they are not themselves required to have secondary containment (since that’s what they are). EPA included the phrase “[t]ank systems, including sumps” in the provision that exempts these secondary containment sumps from duplicative secondary containment requirements. [§§264/265.190(b); see also EPA/530/SW-88/004, January 1988, available from by downloading the report numbered 530SW88004]

The immediate response exemption “is inapplicable to units…designed to serve as the secondary containment for a tank system treating or storing hazardous waste.” [53 FR 34085]

Primary containment sumps

Sumps that provide primary containment for storing hazardous waste are primary containment sumps. Just like primary containment tanks, such sumps are subject to all Subpart J tank standards, including the need for secondary containment. When EPA overhauled the hazardous waste tank regs on July 14, 1986, it stated in the preamble that “sumps may present the same potential for leaks and releases as hazardous waste storage and treatment tanks…. Thus, EPA concludes that sumps generally should be subject to the same standards as tanks.” [51 FR 25441]

The first part of the “sump” definition, then, applies tank standards to these units that collect and transport routine and systematic discharges of hazardous waste if they meet the definition of a tank. [53 FR 34085] For example, sumps used to store hazardous waste generated from periodic reactor cleanouts are primary containment vessels and would be subject to all Subpart J tank standards. However, such primary containment sumps may meet the definition of a WWTU or elementary neutralization unit and, thus, be exempt from RCRA permitting and tank standards under one of those exemptions.

The agency understands that sumps sometimes function differently from tanks and need to be regulated accordingly. For example, sumps that operate as part of a leachate collection and removal system for a landfill, surface impoundment, or waste pile are an integral part of the land disposal unit’s liner system, and imposing Subpart J tank standards (e.g., secondary containment) would be impractical and unnecessary. [January 29, 1992; 57 FR 3471, RO 14011] As such, even though these units provide primary containment for hazardous leachate, they are exempt from these standards.

Sumps holding hazardous waste that don’t pass the parking lot test are surface impoundments and would be regulated under Part 264/265, Subpart K. Imposing tank standards on these structures would be illogical. [RO 11134]


The examples below show how EPA applies the definition of sump in various situations.

Can sumps be used as 90-day units for hazardous waste accumulation?

Yes. Assuming they pass the parking lot test and qualify as tanks, sumps may be used to accumulate hazardous waste for 90 days or less without the need for a RCRA permit. However, such sumps would be subject to Subpart J standards, including the need for secondary containment. [RO 12442]

A sump is used to collect intentional discharges of hazardous waste from a centrifuge. Is it a temporary, secondary containment, or primary containment sump?

It is a primary containment sump, since it collects routine and systematic discharges of hazardous waste. [July 14, 1986; 51 FR 25441]

How are trenches/floor drains that transport hazardous wastewater from a periodic cleaning operation to a sump regulated?

If the sump meets the definition of a tank (i.e., it passes the parking lot test), the sump and associated trenches/floor drains comprise an integrated tank system. Since the sump is receiving hazardous waste on a routine and systematic basis, it is a primary containment sump and does not qualify for the §§264/265.190(b) exemption for sumps or tanks that are part of a secondary containment system. Therefore, unless they qualify for an exemption (e.g., the WWTU exemption), both the sump itself and the ancillary trenches/floor drains would be subject to Subpart J tank standards, including the need for secondary containment. [RO 12829, 13653]

Can a manhole (sump) in a hazardous wastewater distribution system be classified as a tank?

Yes. Since the manhole/sump is part of a secondary containment system, it is a secondary containment sump. Per §§264/265.190(b), it would have to meet all Subpart J requirements, except protection by another secondary containment system. [RO 12788]

What is the regulatory status of a sump associated with a secondary containment system surrounding a hazardous waste-derived fuel truck unloading area at a cement facility?

The sump will contain hazardous waste only in the event of a spill during the offloading of hazardous waste-derived fuel into the cement kiln. It cannot be a primary containment sump, because it doesn’t receive routine or systematic discharges of hazardous waste. In addition, it is not serving as a secondary containment structure for spills from a primary containment vessel storing hazardous waste; the trucks containing the hazardous waste-derived fuel are not storage vessels when located onsite for short periods during the transfer of hazardous waste into the kiln. Since the unit is only used to contain hazardous waste as an immediate response to a spill, it is a temporary sump and qualifies for the immediate response exemption. [RO 13127]


Topic: The Definition of “Treatment”

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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.