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Hazardous Waste

According to The Code of Federal Regulations, Title 40, Paragraph 261.20, a substance is a hazardous waste if it exhibits any of the following 4 hazardous waste characteristics: TCLP, Ignitability, Reactivity, or Corrosivity.

TCLP - Toxicity Characteristic Leaching Procedure

In days of old, waste products were characterized as hazardous under the under the E.P. Toxicity rule. On November 7, 1986 the EPA revised the TCLP rule and promulgated (made known officially) as part of the land disposal restriction. The EPA procedure number for the TCLP preparation is SW-846 Method 1311.

Like the EP TOX, the TCLP rule requires that the laboratory take the solids from a sample, mix with a buffer solution at a ratio of 1:20 for 18 hours, filter the slurry, and analyze the liquid portion for certain listed constituents. This procedure was developed to simulate landfill conditions. Here, we are primarily concerned with any waste that could potentially contaminate the groundwater.


A solid waste can exhibit the characteristic of ignitability. If deemed ignitable by SW-846 Method 1030, then the burn propagation rate is determined. The EPA procedure for the ignitability of liquids, or flash point is SW-846 Method 1010. A liquid is considered flammable and hazardous if the flash point is less than 140 F.


A waste exhibits the characteristics of reactivity if it has any of the following properties:
  • Normally unstable and readily undergoes violent change without detonating;
  • Reacts violently with water
  • Forms potentially explosive mixtures with water
  • When mixed with water, it generates toxic gases, vapors or fumes
  • It is a cyanide- or sulfide-bearing waste which, when exposed to pH conditions between 2 and 12.5, can generate toxic gases, vapors or fumes.
The procedure for reactivity can be found in the SW-846 Methods manual, Chapter 7.3


A waste exhibits the characteristic of corrosivity if it is aqueous and has a pH less than or equal to 2 or greater than or equal to 12.5 as determined by a pH meter, or exhibits a corrosivity to steel in excess of 635 mm/yr.
Corrosivity as pH can be found in SW-846 Methods 9040 and 9045; corrosivity to steel is SW-846 Method 1110.