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RCRA Characteristic Waste

| Ignitability | Corrosivity | Reactivity | Toxicity |

This text has been excerpted from Section III: RCRA Subtitle C - Managing Hazardous Waste,
Chapter 1: Hazardous Waste Identification of the RCRA Orientation Manual on the EPA's web site.

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After a facility determines its waste is a solid waste and is not excluded from the definitions of solid or hazardous waste, it must determine if the waste is a hazardous waste. This entails determining if the waste is listed, and also if the waste is characteristic. Even if a waste is a listed hazardous waste, the facility must then still determine if the waste exhibits a characteristic.

Characteristic wastes are wastes that exhibit measurable properties which indicate that a waste poses enough of a threat to deserve regulation as hazardous waste. EPA tried to identify characteristics which, when present in a waste, can cause death or illness in humans or lead to ecological damage. The characteristics are an essential supplement to the hazardous waste listings. For example, some wastes may not meet any listing description because they do not originate from specific industrial or process sources, but the waste may still pose threats to human health and the environment. As a result, a facility is also required to determine whether such a waste possesses a hazardous property (i.e., exhibits a hazardous waste characteristic). The characteristics are applied to any waste from any industry.

Even if a waste does meet a hazardous waste listing description, the facility must still determine if the waste exhibits a characteristic. If such listed wastes do exhibit a characteristic, the waste poses an additional hazard to human health and the environment, and may necessitate additional regulatory precautions. For example, wastes that are both listed and characteristic may have more extensive LDR requirements, than those that are only listed (the LDR program is fully discussed in Section III, Chapter 6).

EPA decided that the characteristics of hazardous waste should be detectable by using a standardized test method or by applying general knowledge of the waste’s properties. Given these criteria, EPA established four hazardous waste characteristics:  Ignitability, Corrosivity, Reactivity, Toxicity.

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The ignitability characteristic identifies wastes that can readily catch fire and sustain combustion. Many paints, cleaners, and other industrial wastes pose such a hazard. Liquid and nonliquid wastes are treated differently by the ignitability characteristic.

Most ignitable wastes are liquid in physical form. EPA selected a flash point test as the method for determining whether a liquid waste is combustible enough to deserve regulation as hazardous. The flash point test determines the lowest temperature at which the fumes above a waste will ignite when exposed to flame.

Many wastes in solid or nonliquid physical form (e.g., wood, paper) can also readily catch fire and sustain combustion, but EPA did not intend to regulate most of these nonliquid materials as ignitable wastes. A nonliquid waste is considered ignitable if it can spontaneously catch fire or catch fire through friction or absorption of moisture under normal handling conditions and can burn so vigorously that it creates a hazard. Certain compressed gases are also classified as ignitable. Finally, substances meeting the Department of Transportation’s definition of oxidizer are classified as ignitable wastes. Ignitable wastes carry the waste code D001 and are among the most common hazardous wastes. The regulations describing the characteristic of ignitability are codified at 40 CFR §261.21.

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Corrosivity

The corrosivity characteristic identifies wastes that are acidic or alkaline (basic). Such wastes can readily corrode or dissolve flesh, metal, or other materials. They are also among the most common hazardous wastes. An example is waste sulfuric acid from automotive batteries. EPA uses two criteria to identify liquid and aqueous corrosive hazardous wastes. The first is a pH test. Aqueous wastes with a pH greater than or equal to 12.5 or less than or equal to 2 are corrosive. A liquid waste may also be corrosive if it has the ability to corrode steel under specific conditions. Physically solid, nonaqueous wastes are not evaluated for corrosivity. Corrosive wastes carry the waste code D002. The regulations describing the corrosivity characteristic are found at 40 CFR §261.22.

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Reactivity

The reactivity characteristic identifies wastes that readily explode or undergo violent reactions. Common examples are discarded munitions or explosives. In many cases, there is no reliable test method to evaluate a waste’s potential to explode or react violently under common handling conditions. Therefore, EPA uses narrative criteria to define most reactive wastes and requires waste handlers to use their best judgment in determining if a waste is sufficiently reactive to be regulated. This is possible because reactive hazardous wastes are relatively uncommon and the dangers that they pose are believed to be well known to the few waste handlers who deal with them.

A waste is reactive if it meets any of the following criteria:

The reactivity characteristic is described in the regulations at 40 CFR §261.23.

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Toxicity

When hazardous waste is disposed of in a land disposal unit, toxic compounds or elements can leach into underground drinking water supplies and expose users of the water to hazardous chemicals and constituents. EPA developed the toxicity characteristic (TC) to identify wastes likely to leach dangerous concentrations of toxic chemicals into ground water.

In order to predict whether any particular waste is likely to leach chemicals into ground water at dangerous levels, EPA designed a lab procedure to replicate the leaching process and other conditions that occur when wastes are buried in a typical municipal landfill. This lab procedure is known as the Toxicity Characteristic Leaching Procedure (TCLP).

The regulations require a facility to apply the TCLP to its hazardous waste samples in order to create a liquid leachate. This leachate would be similar to the leachate generated by a landfill containing a mixture of household and industrial wastes. Once this leachate is created via the TCLP, the waste handler must determine whether it contains any of 40 different toxic chemicals in amounts above the specified regulatory levels (see Figure III-7). These regulatory levels are based on ground water modeling studies and toxicity data that calculate the limit above which these common toxic compounds and elements will threaten human health and the environment. If the leachate sample contains a concentration above the regulatory limit for one of the specified chemicals, the waste exhibits the toxicity characteristic and carries the waste code associated with that compound or element. The regulations describing the toxicity characteristic cannot be individually measured, the regulatory level for total cresols is used.

*if o-, m-, and p-cresols cannot be individually measured, the regulatory level for total cresols is used.

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