Hazardous Waste

The regulations governing hazardous waste identification, classification, generation, management, and disposal are found in Title 40 of the CFR, parts 260-273. These regulations set criteria for hazardous waste generators; transporters; and treatment, storage, and disposal facilities (TSDFs). This includes permitting requirements, enforcement, and corrective action or cleanup. As of 2009, there were approximately 460 TSDFs, 18,000 transporters, and 14,700 large quantity generators (LQGs) on record (U.S. EPA 2014).

Hazardous wastes can be defined as wastes with properties that make them dangerous or potentially harmful to human health or the environment. However, this simple narrative definition would not be sufficient for the development of a regulatory framework capable of ensuring adequate protection. Determining whether a waste is hazardous is paramount because only those wastes that have specific attributes are subject to RCRA Subtitle C regulations. Making such determination is a complex task that is a central component of the hazardous waste management regulations. Readers should refer to relevant RCRA regulations or the RCRA Orientation Manual 2014 (U.S. EPA 2014) for details. This subsection presents a brief coverage of the EPA’s hazardous waste identification process.

For a material to be classified as a hazardous waste, it must be a solid waste. However, hazardous wastes can actually be liquids, solids, containerized gases, or sludge, and by-products of manufacturing processes or simply discarded commercial products, like cleaning fluids or pesticides. The second step of the identification process is to determine if the waste is specifically excluded from regulation as a solid or hazardous waste. If it is not excluded, it should be determined whether it is a listed waste or characteristic waste. The last step is to determine if the waste is delisted.

Identification Process of Hazardous Waste

RCRA “listed wastes” are wastes from common manufacturing and industrial processes, specific industries, and can be generated from discarded commercial products. They are on one of the four EPA hazardous wastes lists: F-list (nonspecific source wastes) in 40 CFR 261.31; К-list (source-specific wastes) in 40 CFR 261.32; and P-list and U-list (discarded commercial chemical products) in 40 CFR 261.33.

RCRA “characteristic wastes” are those exhibiting at least one of the following four characteristics: ignitability, corrosivity, reactivity, or toxicity. Wastes that are hazardous due to ignitability include liquids with flash points below 60°C (140°F), nonliquids that cause fire through specific conditions, ignitable compressed gases, and oxidizers. D001 is the waste code for ignitable hazardous wastes. There are EPA test methods available for ignitability (i.e., SW-846 Test Methods 1010A, 1020B, and 1030). EPA’s SW-846 Compendium (Test Methods for Evaluating Solid Waste: Physical/Chemical Methods Compendium) is EPA’s official collection of methods for use in complying with RCRA regulations. It consists of more than 200 analytical methods for sampling and analyzing waste and other matrices (e.g., air and water). These methods are divided into sections, or “series,” according to the type of method, analyte, and technique used. The entire Compendium is available online (https://www.epa.gov/hw-sw846/sw-846-compendium).

Wastes that are hazardous due to corrosivity include aqueous wastes with a pH <2, a pH> 12.5, or based on the liquid’s ability to corrode steel. D002 is the waste code for corrosive hazardous wastes. The SW-846 Test Method 1110A determines corrosivity toward steel.

The reactivity characteristic identifies wastes that readily explode or undergo violent reactions. There are no test methods for reactivity. Instead, EPA uses narrative criteria to define most reactive wastes. The criteria include: (1) it can explode or violently react when exposed to water or under normal handling conditions; (2) it can create toxic fumes or gases at hazardous levels when exposed to water or under normal waste handling conditions; (3) it can explode if heated under confinement or exposed to a strong igniting source, or it meets the criteria for classification as an explosive under Department of Transportation (DOT) rules; and it generates toxic levels of sulfide or cyanide gas when exposed to a pH range of 2-12.5. D003 is the waste code for reactive hazardous wastes.

To evaluate whether a specific waste is likely to leach toxic chemicals into ground- water, a lab procedure known as the Toxicity Characteristic Leaching Procedure (TCLP) (SW-846 Test Method 1311) is conducted. During the TCLP procedure, the waste sample is extracted with an extraction fluid for 48-72 hours. At the completion of the extraction, the extract will be analyzed if it contains any of 40 different toxic chemicals exceeding the specified regulatory levels (see Table 3.1). If the extract contains a concentration exceeding its corresponding limit, the waste exhibits the toxicity characteristic (TC) and carries the waste code associated with that compound or element. It is considered as a “toxicity characteristic” hazardous waste.

Once a hazardous waste is generated, it may become mixed with other wastes, be treated and produce residues, or be spilled. RCRA provides special regulatory provisions to address the regulatory status of hazardous waste mixtures; treatment, storage, and disposal residues; and contaminated media and debris. These provisions are known as the “mixture rule,” the “derived-from rule,” and the “contained-in policy” (U.S. EPA 2014).

TABLE 3.1

TCLP Regulatory Levels