The entire hazardous waste identification process can be confusing, especially when it comes to understanding the definition of hazardous waste exclusions. We’ve put together this list to help you understand the “mixture” and “derived-from” rules and take advantage of ways to reduce your regulatory burden and hopefully, streamline waste management at your facility.
Proper hazardous waste identification is one of the most challenging parts of a hazardous waste management program, and also the most important. Under the Resource Conservation and Recovery Act (RCRA), solid waste that is generated from the treatment, storage, or disposal of hazardous waste remains hazardous waste unless it is excluded somewhere else in the regulations.
Note: Under RCRA, the term “solid waste” is interchangeable for “waste” and means any waste, whether it is a solid, semi-solid, or liquid.
Did you know that only a small fraction of all RCRA solid wastes actually qualify as hazardous wastes? After identifying whether or not an item is solid waste, determining whether or not a waste is exempt from regulation is the second step in the RCRA hazardous waste identification process.
The Mixture and Derived-from Rules
The mixture and derived-from rules apply to “as-generated industrial wastes” — a term used to describe chemical waste streams that are created during normal manufacturing or industrial operations. Examples of these types of waste are industrial wastewaters, spill residues of hazardous wastes, and pollution control residues such as sludges.
According to EPA, these regulations answer the question, “When do these hazardous wastes cease being regulated as hazardous wastes?” The mixture rule states that any mixture of a listed hazardous waste and a non-hazardous solid waste is an RCRA hazardous waste. The “derived-from” rule is meant to ensure that wastes that may still pose a threat after treatment are not overlooked. It states that any waste derived from the treatment, storage, or disposal of a listed hazardous waste is still considered a listed hazardous waste.
Note: In RCRA regulations, the “Definition of Hazardous Waste” section 261.3 explains in detail the mixture and derived-from rules and regulatory exemptions from these rules.
Listed Wastes vs Characteristic Wastes
The mixture and derived-from rules operate differently for listed wastes and characteristic wastes and are subject to strict principles, even though there are a few exceptions. First, let’s take a look at these two categories of hazardous waste.
For industrial waste handlers, hazardous waste identification by listings makes the identification process easy. EPA includes precise descriptions of wastes from various industrial processes in its regulations as well as wastes from specific sectors of industry and in the form of specific chemical formulations. The bottom line is that once a waste has matched a listing description, it is forever a listed hazardous waste. No matter how it is mixed, treated, or otherwise changed, it is still considered hazardous. Therefore, regardless of its chemical composition, any material that comes in contact with a listed waste is also considered listed. Basically, once a listed waste, always a listed waste.
These wastes are identified as containing a property or “characteristic” that makes them a threat to human health or the environment. The four characteristics of hazardous waste are ignitability, corrosivity, reactivity, and toxicity. For characteristic wastes, these mixtures are considered hazardous only if the mixture itself exhibits a characteristic. Therefore, materials and treatment residues derived from characteristic wastes are hazardous only if they themselves exhibit a characteristic.
Mixture Rule Exemptions
There are eight exemptions from the mixture rule.
- The first rule applies to mixtures of characteristic wastes and specific mining waste and allows certain mixtures to be classified as non-hazardous, even if there are one or more hazardous waste characteristics.
- - 8. The other seven exemptions apply to specific listed hazardous wastes discharged to wastewater treatment facilities and involved situations where relatively small amounts of listed hazardous wastes are found in secondary waste streams. This waste is routed to large-volume wastewater treatment systems. The amount of listed waste must be very small relative to the treatment system’s overall wastewater and the system itself must be regulated under the Clean Water Act.
Derived-From Rule Exemptions
This rule has five regulatory exemptions.
- Materials that are reclaimed from hazardous wastes
Materials that are recycled from listed and characteristic hazardous wastes to make new products or to recover usable materials are no longer solid wastes. If they are not solid wastes, then they are no longer considered hazardous. So although they are “derived from” hazardous waste, they are not considered hazardous if they are used in a manner consistent with a product.
The other four exemptions are very specific and apply to residues from the treatment of specific wastes, using specific treatment processes.
- Spent pickle liquor from the iron and steel industry
The waste from this acid solution (K062) used to finish the surface of steel can be treated by mixing it with lime to form a sludge. The toxic heavy metals in the solution become less dangerous because they are chemically bound within the sludge and the acids are neutralized.
- Waste derived from burning exempt recyclable fuels
- Biological treatment sludge derived-from treatment of K156 and K157 and catalyst inert support media separated from K171 and K172
- Residues from high-temperature metal recovery processing of K061, K062, and F006 (providing certain conditions are met)
If your facility can utilize exclusions like the mixture and “derived-from” exemptions, you can streamline your waste management process and reduce regulatory responsibility. Partnering with a trusted waste services provider can help with the entire hazardous waste identification process as well as with identifying applicable exemptions.