TCLP is a protocol - a method for determining whether a material is toxic and specifically if it meets the toxicity criteria to be a hazardous waste under RCRA.
TCLP is widely used and accepted in the waste community. Many labs can do it, and the results - if the material does not meet the toxic criteria - can provide a good defense if anyone questions your waste. TCLP is often done as a diagnostic when a new waste is found or generated, perhaps as a preliminary for deciding on course of treatment. Your regulatory agency may stipulate that you perform TCLP on a regular basis on materials in your process. You might have to do a TCLP on newly generated waste or on treated or stabilized waste. If your operations are steady and the waste appears to be consistent day to day, the regulatory agency may not require frequent tests. If your process is dynamic, you will probably have to do more frequent tests. If you fail a test at a time, you will probably have to do more tests in the near future.
Make sure you take the sample in a clean container and don’t do anything else to contaminate the sample. Once you have contracted with a lab to do the analysis, that lab can tell you how big your sample should be, and they may actually provide a collection vessel.
One big factor is whether your sample is representative of the waste. If the waste is heterogeneous, this can be a problem.
Labs take a set procedure in handling the sample. If the sample is primarily liquid, it is filtered and analyzed. Solid waste may be crushed if the particle sizes are large; the procedure worked with a maximum particle size of 1 cm. Solids are leached in an acidic solution to generate an extract. This liquid is then analyzed for constituents of interest. Reports will tell you the constituents in mg/liter.
There are several dozen chemicals of concern; if any is present past the limit the waste can be classified as toxic. The Iowa Department of Natural Resources website lists organic compounds and metals that are considered to make a waste toxic under RCRA. https://www.iowadnr.gov/Portals/idnr/uploads/waste/swfact_tclpfactsheet.pdf
You can find a nearby laboratory or environmental services company that will do your analysis and give you a report. Cost is on the order of $1000/sample analyzed.
