What counts as hazardous waste?
Under RCRA a material is hazardous waste if it is first a solid waste, and then either appears on one of the EPA's four lists — F, K, P or U — or exhibits one of four characteristics: ignitability, corrosivity, reactivity or toxicity. Neither route requires the material to look dangerous, and most of the arguments about classification are really arguments about the first step.
It has to be a solid waste first
40 CFR 261.2 defines solid waste, and the name misleads: the definition covers liquids, semi-solids and contained gases as well as solids. A drum of spent solvent is a solid waste. So is a tank of off-specification product once it is discarded rather than used. Material that is still being used for its intended purpose is not waste at all, which is why the question of whether something has been discarded settles more classification disputes than any test does.
Route one: it appears on a list
Four lists, each built on a different idea. A listed waste carries its code regardless of concentration.
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- F
Non-specific sources
40 CFR 261.31. Processes that occur across many industries. F001 to F005 are the spent solvent codes, and F006 covers wastewater treatment sludge from electroplating.
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- K
Specific sources
40 CFR 261.32. Tied to a named industry and a named process, such as K062 for spent pickle liquor from steel finishing.
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- P
Acutely hazardous commercial chemicals
40 CFR 261.33(e). Discarded commercial chemical products, off-specification species and container residues. The quantity thresholds that apply to P-listed waste are far lower than for anything else.
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- U
Other commercial chemicals
40 CFR 261.33(f). The same idea as the P list without the acute designation, and a much longer list.
Route two: it exhibits a characteristic
A waste on no list at all is still hazardous if it behaves in one of four ways. These are the D codes, and they are determined by test or by knowledge of the process.
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- D001
Ignitability
40 CFR 261.21. A liquid with a flash point below 140 degrees Fahrenheit, and also ignitable compressed gases, oxidizers and solids that catch fire through friction or absorption of moisture.
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- D002
Corrosivity
40 CFR 261.22. An aqueous waste at pH 2 or below, or 12.5 or above, or a liquid that corrodes steel faster than a quarter of an inch a year. A spent aqueous cleaner reaches this often.
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- D003
Reactivity
40 CFR 261.23. Unstable material, waste that reacts violently with water, and waste that generates toxic gas when mixed. Described in words rather than by a test number.
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- D004-D043
Toxicity
40 CFR 261.24. The Toxicity Characteristic Leaching Procedure simulates what would leach in a landfill. Exceed the regulatory level for any of the forty listed contaminants and the waste carries that code: D007 for chromium, D008 for lead, D004 for arsenic.
Two rules that decide more cases than the lists do
Both are in 40 CFR 261.3, and both work in the direction people do not expect.
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- Mixture
The mixture rule
A listed hazardous waste mixed with a non-hazardous solid waste makes the whole mixture hazardous. Volume is no defense: a small quantity of listed solvent in a large tank of rinse water brings the tank into the rules.
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- Derived-from
The derived-from rule
Anything generated from treating, storing or disposing of a listed waste carries the same listing. Treatment residue, incinerator ash and filter cake inherit the code of what they came from.
Who makes the determination
The generator does, and 40 CFR 262.11 makes that a duty rather than an option. It can be met by applying knowledge of the process and the materials that went into it, or by testing. Knowledge is accepted and is often the better evidence, because it explains why a waste is what it is instead of recording one sample on one day. What is not accepted is leaving the question open: a waste nobody has classified is still generating obligations while it sits.
Where this comes up
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RCRA Hazardous Waste Disposal
This is the general page. Before a stream can be priced, packaged or sent anywhere, one question has to be answered: is…
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Acute Hazardous Waste Disposal
Acutely hazardous waste is the one category where quantity stops being a useful guide. A site can generate almost nothing by weight…
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Non-Acute Hazardous Waste Disposal
Non-acute is almost everything. It is the routine, high-volume side of hazardous waste — the drums that accumulate in a satellite area,…
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Lab Pack Services
A lab pack is what you need when the problem is variety rather than volume: a shelf, a store room or a…
Still not sure what you have?
A description of the process and a rough quantity is enough to start. A Certified Hazardous Materials Manager reads every request.