California waste code 491 Sludge that matches no named type.

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Based on California Title 22 and DTSC guidance
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Sludges
Other hazardous sludge

None of the named sludge materials or source processes describes it.

Other hazardous sludge, the catch-all when no named sludge material or source process fits. Codes 411 to 481 come first.

Is California code 491 hazardous waste?

Not from the code alone. Waste must first be found hazardous. Code 491 isn't a restricted code, but a restricted category that fits takes priority over it. A code that isn't restricted doesn't make waste non-hazardous.

When a shipment needs the Uniform Hazardous Waste Manifest, enter 491 in Item 13 for the waste line. Use one California code, plus the federal RCRA codes when the waste is federally hazardous.

RCRA waste meets a federal listing or characteristic, with no federal exclusion that applies. Non-RCRA waste is hazardous under California rules only. California presumes hazardous waste is RCRA unless the generator shows it isn't, so keep that determination.

What does California code 491 cover?

This catch-all code is for hazardous sludge only when no more specific material or source-process sludge category fits. Record the categories you considered and why none fits.

Official wording: 22 CCR division 4.5, chapter 11, Appendix XII(b)

Is other hazardous sludge California code 491?

Code	When it fits
491	No more specific material or source-process sludge category describes the hazardous sludge.
Sludge codes	A more specific named material or source-process sludge category describes the waste.

Code 491 is the catch-all. A generic or incomplete profile isn't enough, so record how the material and source process rule out the more specific sludge codes.

Which wastes take California code 491?

Waste	When it’s 491
Other sludge	The material and producing process rule out the named sludge entries

Which codes sit beside California code 491?

Code	What it is
411	Alum or gypsum sludge
421	Lime sludge
431	Phosphate sludge
441	Sulfur sludge
451	Sludge from degreasing
461	Paint sludge
471	Paper-processing sludge or pulp
481	Tetraethyl-lead sludge