Hazardous waste determinations of all wastes are the responsibility of the generator. This applies to all auto body repair shops and any facility operating a parts washer.
Auto body repair shops produce both a liquid and a solid waste. Both the liquid and solid waste must be tested separately.
Spent paint booth filters must also have a on- time representative sample test for their RCRA 8 metals content before being able to be disposed of as a solid waste.
If you are using a hazardous parts washer, the resultant waste will be hazardous and you must comply. If you are using a non-hazardous parts washer, it could become contaminated through use.
The waste (not the original solvent) should be tested or you should have proof based on knowledge to document if the waste is hazardous or non-hazardous.