Determining Toxicity & When to Use the TCLP Test
A solid waste exhibits the characteristic of toxicity if it contains an elevated level of a toxicity contaminant. The toxicity contaminants are listed in Table 1 at 40 CFR 261.24 and include, but are not limited to:
- Heavy Metals—Arsenic, Barium, Cadmium, Chromium, Lead, Mercury, Selenium, and Silver
- Pesticides—Endrin, Lindane, Methoxychlor, Toxaphene, Silvex, and more.
- Volatile Organic Compounds (VOCs)—Benzene, Carbon Tetrachloride, MEK, etc.
- Dioxins—Trichlorophenol and Vinyl Chloride
Waste generators must determine whether or not their waste exhibits any characteristic of hazardous waste. The generator may either test the waste according to approved methods or apply his knowledge of the waste in light of the materials and processes used.
If you know that your waste does not contain any toxicity contaminants, you do not need to test the waste. If you know your waste contains toxicity contaminants, or are uncertain, the test method to use is the Toxicity Characteristic Leaching Procedure (TCLP; EPA Test Method SW-846). The TCLP test method has essentially 6 steps:
- Separate the liquid and solid portions of the waste (as needed).
- Crush the solid portion of the waste.
- Place the crushed solid portion in a system that simulates the conditions of a landfill by filtering a large quantity of water through it.
- Collect the leachate from the system.
- Recombine the separated liquid portion of the waste (if any) with the collected leachate.
- Analyze the leachate for constituents of concern.
The TCLP test is an expensive and time-consuming procedure. It’s important to know that there are three scenarios where the presence of toxicity contaminants does not automatically require testing:- If the waste is 99.5% or more liquid then the waste itself is the extract, and you can analyze it directly without performing the TCLP. [40 CFR 261.24(a)]
- If a total analysis of the waste, not the extract, demonstrates that the individual contaminants are not present in the waste, or present in levels that could not possibly exceed the regulatory threshold, then you don’t need to run the TCLP. [Section 1.2 of the TCLP procedure]
- For wastes that are 100% physically solid, the maximum theoretical leachate concentration is 1/20 of the total concentration in the waste. If this value is below the regulatory threshold, the TCLP need not be run.[60 FR 66389, December 21, 1995]
For example, the regulatory level for the toxicity characteristic for lead (D008) is 5 ppm. Here are three examples of when it is necessary to run a TCLP:
- If a wastewater solution contains 5 ppm or more dissolved lead, then it would be a D008 waste. A lower concentration would not be D008.
- If a semisolid sludge contains 5 ppm or more total lead, then it would be a D008 waste. A lower concentration would not be D008.
- If a solid brick or dry ash contains less than 100 ppm dissolved lead, then the extract could not possibly have more than 5 ppm lead, and the solid could not be a D008.
If a solid brick or dry ash contains 100 ppm (20 times 5 ppm) or more elemental lead, then it is possible that the extract produced by the TCLP could have 5 ppm or more elemental lead, therefore the TCLP or an equivalent procedure must be performed.
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