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- Types of Special Wastes
When EPA proposed regulations for managing hazardous waste under Subtitle C of Resource Conservation and Recovery Act (RCRA) on December 18, 1978 (43 FR 58946), the agency deferred hazardous waste requirements for six categories of waste—which EPA termed “special wastes”—until further study and assessment could be completed to determine their risk to human health and the environment. These wastes typically are generated in large volumes and, at the time, were believed to possess less risk to human health and the environment than the wastes being identified for regulation as hazardous waste.
On October 12, 1980, Congress enacted the Solid Waste Disposal Act Amendments of 1980 (Public Law 96-482), which included the Bentsen and Bevill Amendments (sections 3001(b)(2)(A) and 3001(b)(3)(A)) These new sections exempted “special wastes” from regulation under Subtitle C of RCRA until further study and assessment of risk could be performed. Specifically, the Bentsen Amendment (section 3001(b)(2)(A)) exempted drilling fluids, produced waters, and other wastes associated with the exploration, development, and production of crude oil or natural gas or geothermal energy. The Bevill Amendment (section 3001(b)(3)(A)) exempted fossil fuel combustion waste; waste from the extraction, beneficiation, and processing of ores and minerals (including phosphate rock and overburden from uranium ore mining); and cement kiln dust.
The Bevill and Bentsen Amendments also required EPA to complete full assessments of each exempted waste and submit a formal report to Congress on its findings. Section 8002 explicitly identified the requirements for each special waste study and established deadlines for submission of the final reports. After completion of each respective “Report to Congress”, EPA was then required to make a final regulatory determination within six months as to whether the special waste in question warranted regulation as a hazardous waste under Subtitle C of RCRA.
The EPA submitted Reports to Congress and issued final regulatory determinations for each of the special wastes. For more information on each of the special wastes and links to their regulatory timelines, see the next section.
Categories of special wastes include:
Cement kiln dust (CKD) is a fine-grained solid by-product generated during the cement manufacturing process and captured by the facility’s air pollution control system. Because much of the CKD is unreacted raw materials, it is often returned to the production process. CKD that is not returned to the system, typically due to the presence of undesired constituents such as alkali metals, is disposed of in landfills, or sold for beneficial use. Currently, CKD waste is generally excluded from the definition of hazardous waste under federal regulations.
Certain wastes from the exploration and production of oil, natural gas, and geothermal energy are excluded from hazardous waste regulations under Subtitle C of RCRA. These wastes include those that have been brought to the surface during oil and gas exploration and production operations, and other wastes that have come into contact with the oil and gas production stream (e.g., materials used to process natural gas).
Fossil fuel combustion (FFC) wastes are the wastes produced from the burning of fossil fuels (i.e., coal, oil, natural gas). These wastes can include fly ash, bottom ash, boiler slag and particulates removed from flue gas. During its assessment of the regulatory status of FFC wastes, EPA divided the wastes into two categories:
- Large-volume coal combustion wastes generated at electric utility and independent power producing facilities that are managed separately.
- All remaining FFC wastes, including:
- Large-volume coal combustion waste generated at electric utility and independent power producing facilities that are co-managed with certain other coal combustion wastes (referred to as "co-managed wastes").
- Coal combustion wastes generated at non-utilities.
- Coal combustion wastes generated at facilities with fluidized bed combustion technology.
- Petroleum coke combustion wastes.
- Waste from the combustion of mixtures of coal and other fuels.
- Waste from the combustion of oil.
- Waste from the combustion of natural gas.
After studying these categories of wastes, EPA made two separate regulatory determinations (in 1993 and in 2000) to exclude large- volume coal combustion wastes and the remaining fossil fuel combustion wastes from hazardous waste regulation under Subtitle C of RCRA.
On April 17, 2015, EPA issued federal regulations establishing requirements for the safe disposal of residuals generated from the combustion of coal at electric utilities and independent power producers. These regulations establish technical requirements for CCR landfills and surface impoundments under Subtitle D of RCRA, the nation’s primary law for regulating solid waste. Read more about this rule that went into effect on October 19, 2015.
Mining wastes include waste generated during the extraction, beneficiation, and processing of minerals. Most extraction and beneficiation wastes from hardrock mining (the mining of metallic ores and phosphate rock) and 20 specific mineral processing wastes (see side bar) have been excluded from federal hazardous waste regulations under Subtitle C of the RCRA:
Mineral Processing Wastes Covered by the Mining Waste Exclusion
Slag from primary copper processing
Slag from primary lead processing
Red and brown muds from bauxite refining
Phosphogypsum from phosphoric acid production
Slag from elemental phosphorous production
Gasifier ash from coal gasification
Process wastewater from coal gasification
Calcium sulfate wastewater treatment plant sludge from primary copper processing
Slag tailings from primary copper processing
Flurogypsum from hydrofluoric acid production
Process wastewater from hydrofluoric acid production
Air pollution control dust/sludge from iron blast furnaces
Iron blast furnace slag
Treated residue from roasting/leaching of chrome ore
Process wastewater from primary magnesium processing by the anhydrous process
Process wastewater from phosphoric acid production
Basic oxygen furnace and open hearth furnace air pollution control dust/sludge from carbon steel production
Basic oxygen furnace and open hearth furnace slag from carbon steel production
Chloride process waste solids from titanium tetrachloride production
Slag from primary zinc processing
Extraction is the first phase of hardrock mining which consists of the initial removal of ore from the earth. Beneficiation follows and is the initial attempt at liberating and concentrating the valuable mineral from the extracted ore. After the beneficiation step, the remaining material is often physically and chemically similar to the material (ore or mineral) that entered the operation, except that particle size has been reduced. Beneficiation operations include crushing; grinding; washing; dissolution; crystallization; filtration; sorting; sizing; drying; sintering; pelletizing; briquetting; calcining; roasting in preparation for leaching; gravity concentration; magnetic separation; electrostatic separation; flotation; ion exchange; solvent extraction; electrowinning; precipitation; amalgamation; and heap, dump, vat, tank, and in situ leaching. The extraction and beneficiation of minerals usually generates large quantities of waste.
Mineral processing operations generally follow beneficiation and include techniques that often change the chemical composition the physical structure of the ore or mineral. Examples of mineral processing techniques include smelting, electrolytic refining, and acid attack or digestion. Mineral processing waste streams typically bear little or no resemblance to the materials that entered the operation, producing product and waste streams that are not earthen in character. Twenty mineral processing wastes (see side bar) qualify for the exclusion from federal hazardous waste regulation. The remainder of mineral processing wastes are regulated under RCRA and subject to applicable regulations (e.g., land disposal restrictions.) For more information on the management of mineral processing wastes, visit EPA's Office of Enforcement and Compliance Assurance Mineral Processing Wastes Web page.