How to Make a Hazardous Waste Determination Under RCRA

The Resource Conservation and Recovery Act (RCRA) is one of those federal laws that people in the industry have heard of but don’t always fully understand until something goes wrong. And when it comes to hazardous waste determination, that misunderstanding can cost more than just time.

Making the correct call on whether a waste is a hazardous waste isn’t optional. It’s the first, and legally required, step in handling solid and hazardous waste. If you get this part wrong, the rest of the process will follow suit. Storage, transport, disposal, and emergency planning all depend on that initial determination being accurate.

The EPA takes this seriously. Facilities that fail to make proper determinations can end up on a list of Significant Noncompliers (SNCs), a term the agency uses for sites where there’s “actual exposure or a substantial likelihood of exposure to hazardous waste or hazardous constituents.” That kind of designation can bring steep fines, operational delays, and, in some cases, a total shutdown.

So, who needs to care about this? Short answer: anyone generating waste that might be dangerous. That includes:

• Facility managers trying to stay out of hot water during audits. A sloppy determination can put your whole operation under the microscope.
• EHS professionals who wear six hats and don’t have time to double back on mistakes.
• Small business owners (like those running auto shops or labs) who might assume their waste doesn’t fall under RCRA hazardous waste rules—but it might.

I’ve crossed paths with all of these folks over the years, and the pattern is the same: When the waste determination gets overlooked or rushed, it creates more work later. And sometimes more risk than anyone expected.

Key Takeaways

• Hazardous waste determination is legally required at the point of generation and must be based on testing, SDSs, or process knowledge—guesswork or assumptions won’t hold up during inspections.
• All hazardous waste is solid waste under RCRA, but not all solid waste is hazardous. Understanding this distinction is essential when evaluating exclusions, exemptions, and classifications.
• Waste can be regulated under RCRA if it’s listed or exhibits one or more characteristics of hazardous waste (ignitability, corrosivity, reactivity, toxicity), even if it doesn't look or behave like something dangerous.
• Small generators are not exempt from compliance, as RCRA requirements like proper labeling, recordkeeping, and manifest use apply even to those producing limited quantities of solid and hazardous waste.

Step 1: Is It a Solid Waste?

This is the part that catches people off guard, mainly because of the word solid. I’ve had folks say, “Well, it’s a liquid, so it can’t be solid waste, right?” But under RCRA, the term covers a lot more than just solids. If you skip this first question or make assumptions about what qualifies, the whole hazardous waste determination can fall apart before it even begins.

What Is Solid Waste?

Under RCRA, “solid waste” doesn’t just mean dry, compact material. It includes solids, liquids, gases, and semi-solids—basically, any discarded material. The keyword here is discarded. If something is thrown away, recycled improperly, or abandoned, it could fall under this definition.

It’s a common misconception that only obviously “hazardous” stuff is regulated. But under RCRA rules, all hazardous waste is solid waste, though not all solid waste is hazardous. That distinction is where people get turned around.

Here are a few examples I’ve come across that typically qualify as solid waste:

• Spent solvents used in degreasing or cleaning equipment. Once they’ve been used and can’t be reused as-is, they’re considered discarded.
• Industrial sludges from wastewater treatment processes. These often come with heavy metals or other residuals that may push them into the hazardous category later.
• Discarded commercial chemical products, like expired lab reagents or half-used containers of old pesticides.
• Contaminated soil from spill response activities or construction near former industrial sites. Even if it’s dirt, it may be considered solid waste under RCRA.

This is the foundation of any hazardous waste determination. If it’s not a solid waste, the rest of the process doesn’t apply. But if it is, then you move forward to figure out if it meets any of the criteria for being RCRA hazardous waste.

Solid Waste Exclusions

Not everything that gets tossed out is considered solid waste under RCRA. Some materials are specifically excluded, and if you don’t check for these, you might end up managing waste you didn’t need to manage in the first place. Here are a few key exclusions:

• Domestic sewage and any mixture of domestic sewage and other wastes that pass through a sewer system to a publicly-owned treatment works
• Industrial wastewater discharges regulated under the Clean Water Act
• Irrigation return flows
• Source, special nuclear, or byproduct material as defined by the Atomic Energy Act
• Materials subjected to in-situ mining techniques that aren't removed from the ground
• Pulping liquors that are reclaimed in a pulping liquor recovery furnace and reused in the pulping process
• Spent sulfuric acid used to produce virgin sulfuric acid
• Secondary materials that are reclaimed and returned to the original production process
• Household hazardous waste, including garbage and trash from households
• Agricultural wastes returned to the soil as fertilizers

These exclusions mean the material isn’t considered solid waste under RCRA, so a hazardous waste determination isn’t even needed. But if none of them apply, you're still not done. Before calling it RCRA hazardous waste, you need to check whether it qualifies for a hazardous waste exemption instead.

Step 2: Is the Waste Excluded from RCRA Hazardous Waste Regulations?

Once you’ve confirmed you’re dealing with a solid waste, the next question is whether it’s regulated as RCRA hazardous waste (or if it qualifies for an exemption).

Some materials are still considered solid waste, but RCRA doesn’t regulate them as hazardous, often because of how they’re reused, recycled, or where they originate. These are known as hazardous waste exemptions, and knowing when they apply can save you from unnecessary storage and disposal requirements.

Hazardous Waste Exemptions

• Household hazardous waste (from homes, not businesses)
• Used oil sent for legitimate hazardous waste recycling
• Scrap metal recycled into usable feedstock
• Bevill exemption (certain mining and mineral processing wastes)
• Spent wood preserving solutions reused on-site
• Petroleum-contaminated media and debris from UST cleanup
• Leachate from landfills under specific conditions
• Excluded recycled materials under 40 CFR §261.6(a)(3)

If your waste falls under any of these RCRA exemptions, you’re not off the hook entirely, but you’re no longer subject to the full set of hazardous waste rules. Just be ready to explain it. I have heard of enforcement actions being taken down not because someone used the wrong category but because they couldn’t prove the waste qualified for the exemption in the first place.

Documentation is everything here, so keep your process notes, any SDSs, internal reuse protocols, or recycling receipts on file. If it’s not written down, it doesn’t count.

Step 3: Is It a Listed Waste?

By this point, you’ve ruled out exclusions and exemptions, which means you’re dealing with a solid waste that’s potentially regulated as RCRA hazardous waste. The next step is checking whether it’s an RCRA listed waste. If it appears on one of the EPA’s official lists, it’s automatically regulated as hazardous waste.

What Are Listed Wastes?

An RCRA listed waste is any waste the EPA has specifically identified as hazardous based on how it’s generated or the chemicals it contains. These wastes show up on one of four lists: F, K, P, and U.

• F-List (Non-specific sources): These are wastes from common manufacturing or industrial processes, like spent solvents or wastewater treatment sludges. The process that generates them isn’t tied to a specific industry.
• K-List (Source specific wastes): These come from specific industries like petroleum refining, pesticide manufacturing, or wood preservation. The waste is hazardous because of the exact process that created it.
• P-List (Acutely hazardous commercial chemicals): Pure and unused chemicals that are especially dangerous in small quantities, like sodium azide or arsenic trioxide. Even trace amounts can trigger regulation.
• U-List (Toxic commercial chemicals): Also unused commercial products, but less acutely hazardous than the P-list. Think chloroform, formaldehyde, or acetone.

If a waste material matches any of these codes based on its ingredients or how it was generated, it's an RCRA listed waste even if it doesn’t look hazardous or behave like one.

How to Check if a Waste Is Listed

To figure out whether your waste is an RCRA listed waste, you’ll need more than just a visual inspection or a guess based on smell or color. This step takes a little research.

Start with these tools:

• Safety Data Sheets (SDS): Look for chemical names, CAS numbers, and hazard information. Many listed wastes are tied to specific active ingredients.
• EPA hazardous waste codes: Each RCRA listed waste has a code (like F001 or U129) and a description. These are published in 40 CFR §261.31 through §261.33.
• Process knowledge: If you know how the waste was generated and what materials were used, you can match it against the descriptions in the F or K lists.
• Product labels and technical sheets: These often reference regulated ingredients that match P- or U-listed substances.

For example:

• A shop that uses methylene chloride as a degreaser may generate F002 waste if the solvent is spent.
• If you discard an unused container of epinephrine, that’s a P042 RCRA listed waste.
• Leftover toluene from a lab that’s being discarded could be U220.

I’ve had conversations with teams who initially ruled out regulation because a waste didn’t seem hazardous on the surface. But the SDS listed a chemical tied to an RCRA listed waste, and since it was the primary ingredient, that overrode everything else. One match on that list can trigger full hazardous waste handling, even if the material doesn't behave the way you'd expect.

Step 4: What Are Considered Characteristic Wastes?

If your waste isn’t excluded, exempt, or an RCRA listed waste, you’re still not in the clear. You now have to ask whether it qualifies as a characteristic waste. This means the waste might not be named on any list, but it still shows hazardous traits like ignitability or toxicity. These traits are defined by the EPA and can apply to anything from used solvents to industrial byproducts to contaminated cleanup materials.

Ignitability

A characteristic waste is considered ignitable if it can catch fire under certain conditions, as defined in 40 CFR § 261.21. That includes liquids with low flash points, solids that burn through friction or spontaneous chemical reactions, and even pressurized gases that feed combustion.

I once spotted drums of used paint thinner in a storage area, like those in the image above, marked as flammable. Shops handle solid waste like this all the time, and it needs a hazardous waste determination to confirm it’s RCRA hazardous waste. Low flash point liquids aren’t just regular trash.

You’ll see other wastes like this in different settings. These are some common ones that need the same RCRA hazardous waste check:

• Liquids with a flash point below 140°F (60°C), such as used acetone, toluene, or paint thinners. These are common in manufacturing and auto body operations.
• Solids that ignite easily when exposed to air or moisture, like oily rags or powdered aluminum.
• Ignitable compressed gases or oxidizers, which can be found in aerosol cans, sterilants, and some lab stock.

Corrosivity

Under 40 CFR § 261.22, a characteristic waste is corrosive if it has a pH less than or equal to 2 or greater than or equal to 12.5, or if it can corrode steel at a rate greater than 6.35 mm per year. Corrosivity applies to both acids and bases, and the classification is based entirely on measurable properties, usually confirmed through pH testing or corrosion rate analysis.

Wastes that often meet this definition include:

• Spent acid solutions from pickling or etching processes
• Caustic cleaners used in equipment or surface preparation
• Wastewater containing residual chemical treatments

As part of any hazardous waste determination, checking pH is a direct way to identify whether a solid waste meets the EPA's definition of RCRA hazardous waste through the corrosivity characteristic. This step matters in both large-scale operations and smaller maintenance settings where chemical residues are involved.

Reactivity

As defined in 40 CFR § 261.23, a characteristic waste is reactive if it’s unstable under normal conditions or can cause violent chemical changes, explosions, or release toxic gases when exposed to water, air, or other substances. This characteristic is less common than ignitability or corrosivity, but when it shows up, it usually carries more immediate risk.

Examples of reactive wastes include:

• Unused explosives or outdated reactive chemicals
• Cyanide- or sulfide-bearing wastes that emit toxic gases under acidic conditions
• Lithium batteries or reactive metals stored improperly
• Compressed gas cylinders that may rupture or detonate when exposed to heat

Reactivity is one of the characteristics of hazardous waste that often requires process knowledge, since not all reactions are visible or predictable without understanding the chemical behavior. Any time you're evaluating solid and hazardous waste with potential for unexpected gas release, detonation, or violent reaction, reactivity must be part of the hazardous waste determination.

Toxicity

According to 40 CFR § 261.24, a characteristic waste is toxic if it fails the Toxicity Characteristic Leaching Procedure (TCLP). This test simulates leaching in a landfill environment. If certain contaminants are found above EPA regulatory thresholds, the toxic waste is classified as RCRA hazardous waste.

Examples include:

• Heavy metals in spent catalysts, batteries, or solder debris
• Pesticide residues in containers or rinsates
• Solvent-contaminated wipes or soil
• Ash or industrial sludge with residual contaminants

Below are some of the key regulated metals under the toxicity characteristic, with their EPA threshold concentrations:

NOTE: If your waste contains both radioactive and hazardous components, it's considered mixed waste and is subject to additional regulations under the Atomic Energy Act. This type of waste involves overlapping oversight from the EPA and the NRC, and carries unique handling and storage requirements.

Recordkeeping & Documentation

If there’s one part of the hazardous waste determination process people try to rush through, it’s the documentation. I’ve had more than one conversation that started with “Well, we did make the call correctly; we just didn’t write it down.” That doesn’t go very far if someone asks to see your files.

Under 40 CFR Part 262, you’re required to document how you decided whether a waste is—or isn’t—regulated as RCRA hazardous waste. That applies to all generators, not just the big ones. Whether you used lab data or just relied on SDSs and process knowledge, it needs to be written down and traceable.

Here’s a quick breakdown of what should be in your records:

A few things I always recommend:

1. Three years is the minimum you have to keep these records, but keeping them longer doesn’t hurt, especially if you’re in a high-turnover environment.
2. If the waste stream or process changes, update your determination. Even small formulation changes can shift your classification.
3. If you’re using electronic records, make sure someone else knows how to pull them during an inspection. From my experience, I’ve learned that delays with records tend to raise questions that weren’t even on the table to begin with.

The point isn’t just to check a box but to be able to explain your decisions with something more than a shrug if questions come up.

Lessons from Real Violations

I’ve read through more EPA case summaries than I can count, and most of the time, the issue isn’t some dramatic chemical spill but someone skipping a step in their hazardous waste determination, or assuming their waste didn’t count because it looked harmless. What starts as a small oversight often turns into thousands in penalties or forced corrective actions.

Here are a few real examples that show what can happen when the determination process is incomplete, undocumented, or done too casually.

Misclassified Consumer Products

This one caught my attention because it involved everyday items—cleaners, aerosols, and unsold store products. The facility didn’t evaluate whether those returned or discarded items were RCRA hazardous waste before tossing them. A lot of them likely met the definition of characteristic waste, especially for ignitability or toxicity.

• Violation: Skipped waste determinations for discarded consumer goods
• Penalty: $500,000 civil fine
• Lesson: Just because something comes off a retail shelf doesn’t mean it’s safe to landfill. If you’re discarding in volume, the rules still apply.

Missed Determinations at a Car Plant

I remember this one because it showed that even high-tech operations can trip over the basics. One facility failed to evaluate some of its production waste. The EPA also flagged them for air emissions issues and poor recordkeeping.

• Violation: Failed hazardous waste determinations and generator compliance issues
• Penalty: $31,000 fine + $55,000 in emergency response equipment
• Lesson: Tech-driven or not, you still have to test and document your solid and hazardous waste like anyone else.

Recycling Facility Didn’t Evaluate Waste

This one in particular stood out to me because the company was in the business of handling waste—solvent recycling, fuel blending, that sort of thing. The EPA found they hadn’t evaluated some of their own waste streams and were storing ignitable materials with inadequate safety systems.

• Violation: No hazardous waste evaluation; unsafe storage
• Penalty: $120,527 civil penalty
• Lesson: Recycling facilities aren’t off the hook. If you’re generating solid waste, you still have to check whether it’s RCRA hazardous waste.

Skipped Testing, Skipped Compliance

At these oil and antifreeze processing sites, the EPA found waste streams that were never tested and lacked any land disposal documentation. I flagged this one because it’s a common blind spot—assuming used fluids are exempt without checking the numbers.

• Violation: Failed to test for hazardous characteristics; missing land disposal documentation
• Penalty: $39,092 fine + $167,967 in air filters for schools
• Lesson: If you’re handling multiple waste streams, especially aqueous wastes, you need lab results, a documented basis for your classification, or an equivalent test method approved by the Administrator under 40 CFR § 260.21.

If there’s one thing these cases make clear, it’s that the size of your operation doesn’t matter. You can be a small plating shop or a giant automaker—if the hazardous waste determination is missing or wrong, enforcement follows. And it usually costs more to fix it after the fact than to get it right from the start.

Small Generators, Big Risks

Smaller operations like labs, dental clinics, or repair shops sometimes assume their waste is too minimal to fall under the same rules.

I get why that comes up. When you're not dealing with drums or bulk chemicals, it’s easy to think the hazardous waste determination rules don’t apply. But according to the EPA, even if you're generating between 100 and 1,000 kilograms of hazardous waste per month, you’re classified as a Small Quantity Generator (SQG)—and the rules still apply.

A lot of smaller facilities overlook just how quickly the waste adds up. Some assume that tossing solvent rags or expired chemicals into the trash is fine because the quantities seem too small to matter. But size doesn’t let you skip the rules; what matters is whether the waste was evaluated and documented correctly. If not, it’s still a violation.

The EPA lays out clear requirements for SQGs. If you fall into that category, you need to:

• Make a proper hazardous waste determination under 40 CFR § 262.11: You can’t assume something’s not hazardous—you need test results, SDSs, or process knowledge to back it up.
• Use correct labeling and storage practices: That means closed containers, proper signage, and sticking to accumulation time limits (usually 180 days).
• Keep documentation and manifests: If you're shipping waste off-site, it must be tracked with a manifest. No exceptions based on generator size.

Too often, violations happen not because of the waste itself, but because someone didn’t know the threshold or forgot to keep the paperwork. The bottom line is this: being small doesn’t make you invisible. If you generate hazardous waste (even just a few containers a month) you need to treat it with the same level of care as any larger facility.

FAQs

What is municipal solid waste?

Municipal solid waste refers to everyday trash and garbage collected from homes, schools, businesses, and institutions. It includes things like food scraps, packaging, furniture, appliances, and yard waste. While it’s mostly non-hazardous, certain items, like batteries or cleaning fluids, can blur the line between solid and hazardous waste, depending on how they’re disposed of.

Who is responsible for making a hazardous waste determination?

The generator of the waste is always responsible. That means any person or business that produces a waste must determine whether it’s hazardous under RCRA. This includes evaluating whether the waste is listed or meets any of the characteristics of hazardous waste such as ignitability, corrosivity, reactivity, or toxicity. Proper documentation of the determination is also required.

When must a hazardous waste determination be made?

The determination must be made at the point of waste generation—when a material first becomes a waste. That’s before it’s stored, treated, transported, or disposed of. Waiting too long or skipping this step can result in mismanagement of solid and hazardous waste and lead to enforcement action.

What does OSHA define as hazardous waste?

OSHA refers to hazardous waste primarily in the context of worker safety, often aligning with the EPA’s definition under RCRA. It considers hazardous waste as any waste that poses a human health or safety risk to employees during handling, exposure, or cleanup. OSHA’s HAZWOPER standard applies to workers involved in the cleanup of such waste, especially when it involves characteristics of hazardous waste or uncontrolled releases.

What is NIMBY and how does it relate to dealing with solid and hazardous waste?

NIMBY stands for “Not In My Back Yard.” It’s a public reaction where people support waste management or environmental protection efforts, just not near their homes or communities. This mindset often complicates the siting of landfills, treatment facilities, or storage locations for solid and hazardous waste, even when the operations are safe and legal. It highlights the need for clear communication, community involvement, and transparency in how waste is managed, especially when RCRA exemptions or facility classifications come into play.