Under the RCRA (§1004, 42 USC §6903), hazardous waste is defined as any solid waste which, because of its quantity, concentration, or physical, chemical, or infectious characteristics may—
(A) cause, or significantly contribute to an increase in mortality or an increase in serious irreversible, or incapacitating reversible, illness; or
(B) pose a substantial present or potential hazard to human health or the environment when improperly treated, stored, transported, or disposed of, or otherwise managed (RCRA §1004, 42 USC 6903).
12. Code of Federal Regulations. Title 40, parts 264, 265. Manifest requirements and the reporting requirements are in Subparts E of these parts.
Solid waste is considered hazardous if it is listed as hazardous or if it has hazardous characteristics.13 If the EPA designates a waste hazardous through rulemaking, then it is a listed hazardous waste. Alternatively, the EPA can find a waste to be hazardous based upon the waste's characteristics.
The EPA has developed four criteria for measuring the characteristics of substances: ignitability, corrosivity, reactivity, and toxicity (RCRA §1022[a], 42 USC §6921[a]). Depending on their classification, wastes are assigned a hazardous waste classification number: ignitable (D001), corrosive (D002), and reactive (D003).
A liquid solid waste is determined ignitable if it has a flash point lower than 60 degrees centigrade.14 A solid material is ignitable if it is "capable at a temperature of 25 degrees centigrade and a pressure of one atmosphere, of causing fire through friction, absorption of moisture or spontaneous chemical changes, and when ignited, burns so vigorously and persistently that it creates a hazard" (40 CFR §261.21).
A corrosive waste is a solid waste with a pH of less than 2 or greater than 12.5 (40 CFR §261.22). Reactive wastes are solid wastes which are normally unstable, react violently or generate toxic fumes when they come in contact with water, contain cyanide or sulfide, (when exposed to pH conditions between 2 and 12.5) generate toxic fumes, or are explosive.
The final criterion for determining a hazardous waste is the toxicity characteristic. This characteristic is determined by the toxicity characteristic leachate procedure (TCLP) test.15 Waste which contains concentrations greater than those listed in the TCLP tables are considered toxicity characteristic hazardous wastes.16
Specific rules apply to mixtures of a hazardous waste with nonhazardous waste, as well as to their treatment. The mixture of toxicity characteristic hazardous waste with nonhazardous waste is considered hazardous if it retains a hazardous characteristic (40 CFR §261.3[a][iii]). The mixture of listed hazardous waste with nonhazardous waste is considered hazardous unless other criteria are met.17 Finally, any residue from the treatment of listed or toxicity characteristic hazardous wastes is also considered hazardous waste.18
13. Certain solid wastes including household wastes are excluded from hazardous waste designation depending on conditions. Code of Federal Regulations. Title 40, sec. 261.4.
14. 140 degrees Fahrenheit. Code of Federal Regulations. Title 40, sec. 261.21.
15. In the past, the EPA used the extraction procedure (EP) test which was designed to test for inorganic compounds only. The current TCLP test can test for both inorganic and organic compounds.
16. See Code of Federal Regulations. Title 40, sec. 261.24, Table No. 1.
18. This rule is known as the derived-from rule. Ibid., sec. 261.3(c)(2).
Hazardous wastes are regulated under the RCRA's subtitle C which incorporates the manifest system to track waste from its point of generation to its point of disposal. The regulations vary according to where the hazardous waste is located and how long the waste will remain at the site. Generally, the RCRA regulates generators; transporters; and treatment, storage, and disposal facilities (TSDFs).
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