April 14, 2014

Hazardous Waste Determination for an Unknown Waste

You find a drum of unknown waste in the back of your warehouse, or someone dumps a drum of unknown liquid at your facility. What now?

If the waste was not yours to begin with, there are rare cases where your local government may help you manage the abandoned waste. But in most situations, you are now the owner of a solid waste and need to determine if your newly acquired waste is hazardous.

It is usually difficult to determine if an unknown waste is hazardous based solely on visual inspection and the limited knowledge you have. So, a sample will often have to be analyzed. Remember the constituents of this waste are unknown, so make sure to wear the appropriate personal protective equipment (PPE).

Listed hazardous waste codes are assigned based on the sources of, or the processes that generated, the waste, rather than the concentrations of hazardous constituents. Therefore, analytical testing alone, without information on a waste’s source, will not produce information that will conclusively indicate whether a waste meets a listing description. If after making a good-faith effort, you are unable to determine the source of the waste, it can only be hazardous if it exhibits a characteristic. [RO 13181, 13586, 14291]

When it comes to determining whether the waste is characteristic, we have heard many different versions of what to ask the lab to test for, but the following is a consensus supplemented with limited EPA guidance.

As an alternative to running the TCLP (which can be expensive), some facilities will ask the lab to run totals for the 40 constituents in §261.24. Based on those results, the TCLP may then be requested only for those constituents with the potential to exceed regulatory levels.


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This document addresses issues of a general nature related to the federal RCRA regulations. Persons evaluating specific circumstances dealing with the RCRA regulations should review state and local laws and regulations, which may be more stringent than federal requirements. In addition, the assistance of a qualified professional should be enlisted to address any site-specific circumstances.