Hazardous Waste Determination Guide - Listed vs. Characteristic Waste
How to determine if waste is hazardous: listed wastes, characteristic wastes, TCLP, the four characteristics, and generator knowledge.
The Waste Determination Process
Every generator of waste is responsible for determining whether their waste is hazardous. This is not optional - it is one of the most fundamental requirements under RCRA and applies to every business that generates waste, regardless of size. The determination must be made at the point of generation and must be documented.
Step 1: Is It a Solid Waste?
Under RCRA, “solid waste” has a broader meaning than the everyday term. It includes any discarded material - solid, liquid, semi-solid, or contained gaseous material - that is abandoned, recycled, or inherently waste-like. If the material is not a solid waste under RCRA’s definition, it is not subject to hazardous waste regulation.
Common exclusions from the solid waste definition include:
- Domestic sewage and mixtures of domestic sewage passing through a sewer system to a publicly owned treatment works (POTW)
- Industrial wastewater discharges subject to Clean Water Act permits
- Certain recycled materials used directly as ingredients in production processes
- Certain materials returned to the original process
Step 2: Is It Excluded or Exempt?
Certain solid wastes are specifically excluded from hazardous waste regulation even if they would otherwise be hazardous. Key exclusions include:
- Household hazardous waste
- Agricultural waste returned to the soil as fertilizer
- Mining overburden returned to the mine site
- Certain utility waste (coal combustion residuals managed under specific rules)
- Samples collected for testing (within the sample exemption limits)
- Empty containers that previously held hazardous waste (if properly emptied)
Step 3: Is It a Listed Waste?
EPA maintains four lists of specific hazardous wastes:
F-List (Non-Specific Source Wastes): Wastes from common industrial and manufacturing processes not specific to a single industry. Examples: spent halogenated solvents (F001-F005), electroplating waste (F006-F012), wastewater treatment sludges from certain processes.
K-List (Specific Source Wastes): Wastes from specific industries. Examples: bottom sediment sludge from wood preserving (K001), wastewater treatment sludge from petroleum refining (K048-K052).
U-List (Discarded Commercial Chemical Products): Unused or off-specification commercial chemical products when discarded. The chemical must be the sole active ingredient, or an unused formulation that contains the listed chemical as the sole active ingredient. Examples: acetone (U002), benzene (U019), chloroform (U044).
P-List (Acutely Hazardous Discarded Commercial Chemical Products): Same as U-list but for acutely hazardous chemicals. Much lower quantity thresholds - generating more than 1 kg of P-listed waste in a month makes you an LQG. Examples: arsenic trioxide (P012), cyanide salts (P030), dieldrin (P037).
If a waste is listed, it is hazardous regardless of its actual characteristics. A listed waste remains hazardous unless delisted through a formal EPA petition process.
The Derived-From Rule
Any waste derived from the treatment, storage, or disposal of a listed hazardous waste is itself a listed hazardous waste, even if the derived waste no longer exhibits any hazardous characteristic. For example, ash from the incineration of a listed waste is still a listed hazardous waste.
The Mixture Rule
Any solid waste mixed with a listed hazardous waste is itself a listed hazardous waste, regardless of the concentration.
These rules are critical - they mean that once a waste stream picks up a listing, it carries that listing through all subsequent management steps unless formally delisted.
Step 4: Does It Exhibit a Hazardous Characteristic?
Even if a waste is not listed, it is hazardous if it exhibits any of the four characteristics:
Ignitability (D001)
A waste is ignitable if it has any of the following properties:
- Liquid with a flash point below 140 degrees F (60 degrees C) - except aqueous solutions with less than 24% alcohol
- Non-liquid capable of causing fire through friction, absorption of moisture, or spontaneous chemical change
- An ignitable compressed gas per DOT regulations
- An oxidizer per DOT regulations
Common D001 wastes: waste solvents, waste fuels, certain paint wastes.
Corrosivity (D002)
A waste is corrosive if:
- Aqueous with pH less than or equal to 2 (strongly acidic) or greater than or equal to 12.5 (strongly basic)
- Liquid that corrodes SAE 1020 steel at a rate greater than 6.35 mm per year at 55 degrees C
Common D002 wastes: waste acid, waste caustic, battery acid.
Reactivity (D003)
A waste is reactive if it:
- Is normally unstable and readily undergoes violent change without detonation
- Reacts violently with water
- Forms potentially explosive mixtures with water
- Generates toxic gases when mixed with water
- Is a cyanide or sulfide-bearing waste that generates toxic gases at pH between 2 and 12.5
- Is capable of detonation or explosive reaction
- Is a DOT-defined forbidden explosive, Class 1 Division 1.1, or Division 1.2 explosive
Common D003 wastes: waste explosives, certain cyanide-bearing plating wastes, waste oxidizers.
Toxicity (D004-D043)
A waste exhibits the toxicity characteristic if the TCLP extract contains any of 40 specified contaminants above the regulatory level.
TCLP - Toxicity Characteristic Leaching Procedure
The TCLP (SW-846 Method 1311) simulates the leaching that would occur if the waste were disposed of in a municipal landfill. The test involves:
- Particle size reduction (if necessary) to pass a 9.5 mm sieve
- Extraction with an acidic solution (one of two extraction fluids, selected based on the waste’s alkalinity)
- 18-hour rotation of the waste/fluid mixture
- Filtration and analysis of the extract for 40 contaminants
The 40 TCLP contaminants include 8 metals and 32 organic compounds. The most commonly relevant for environmental consulting are the 8 RCRA metals:
| Contaminant | Waste Code | Regulatory Level (mg/L) |
|---|---|---|
| Arsenic | D004 | 5.0 |
| Barium | D005 | 100.0 |
| Cadmium | D006 | 1.0 |
| Chromium | D007 | 5.0 |
| Lead | D008 | 5.0 |
| Mercury | D009 | 0.2 |
| Selenium | D010 | 1.0 |
| Silver | D011 | 5.0 |
The organic contaminants (D012-D043) include common VOCs (benzene, carbon tetrachloride, chloroform, vinyl chloride), pesticides (lindane, endrin, toxaphene), and other compounds. TCLP regulatory levels for organics range from 0.002 mg/L (2,4,5-TP) to 200 mg/L (cresol).
If any contaminant in the TCLP extract exceeds its regulatory level, the waste is a characteristic hazardous waste for toxicity and carries the corresponding D-code.
Making the Determination
Testing
Collect a representative sample of the waste and submit it to a laboratory for the appropriate analyses. For toxicity characteristic determinations, request TCLP analysis for the contaminants of concern. For ignitability, request flash point testing. For corrosivity, request pH measurement.
Representative sampling is critical - a single grab sample may not adequately characterize a variable waste stream. EPA SW-846 Chapter 9 provides guidance on sample collection strategies.
Generator Knowledge
Generators may make the hazardous waste determination based on knowledge of the waste’s composition and the processes that generated it. This is acceptable when:
- The waste is generated from a well-characterized process with consistent inputs
- Material Safety Data Sheets (SDSs) or analytical data for the raw materials are available
- The generator has historical analytical data for the waste stream
- The waste is from a process where the hazardous characteristics are well understood
Generator knowledge must be documented and supportable. Maintain records of the basis for your determination, including SDSs, process descriptions, and any analytical data used.
Under the Generator Improvements Rule, generators must re-evaluate their waste determination whenever the process, raw materials, or other conditions change in a way that could affect the waste’s characteristics.
Land Disposal Restrictions (LDR)
Hazardous waste subject to land disposal restrictions must be treated to meet specific treatment standards before it can be land disposed. Generators must:
- Determine applicable treatment standards (OAC 3745-270-40)
- For characteristic wastes, identify any underlying hazardous constituents (UHCs)
- Submit a one-time LDR notification to the receiving TSDF
- Maintain records of the determination
Resources
- Ohio EPA Hazardous Waste Identification- EPA SW-846 Test Methods{target=“_blank”} - Including TCLP Method 1311
- 40 CFR 261{target=“_blank”} - Federal hazardous waste identification rules
- OAC 3745-51{target=“_blank”} - Ohio hazardous waste identification
- RCRA Generator Requirements - Ohio
- Ohio RCRA and Hazardous Waste Program Overview
Frequently Asked Questions
What makes a waste hazardous?
A solid waste is hazardous if it is specifically listed by EPA (F, K, U, or P list), or if it exhibits one or more of four characteristics: ignitability, corrosivity, reactivity, or toxicity. The generator is responsible for making this determination using either testing or knowledge of the waste's composition and the processes that generated it.
What is TCLP?
The Toxicity Characteristic Leaching Procedure (TCLP, SW-846 Method 1311) is the test used to determine if a waste exhibits the toxicity characteristic. The test simulates landfill conditions by extracting the waste with an acidic solution and analyzing the extract for 40 specific contaminants. If any contaminant in the extract exceeds its regulatory level, the waste is characteristic hazardous for toxicity (D-code waste).
Can I use generator knowledge instead of testing?
Yes. Generators may make a hazardous waste determination based on their knowledge of the waste composition, the raw materials used, the processes that generated the waste, and available analytical data. Generator knowledge is acceptable under RCRA, but the determination must be documented and supportable. When in doubt, test the waste - generator knowledge is not a substitute for testing when the waste composition is uncertain.
What is the difference between a listed waste and a characteristic waste?
A listed waste is specifically identified by EPA on one of four lists (F, K, U, or P) based on the source or chemical composition. A characteristic waste is any solid waste that exhibits one of the four hazardous characteristics (ignitability, corrosivity, reactivity, toxicity) regardless of whether it appears on a list. A waste can be both listed and characteristic. The distinction matters because listed wastes cannot lose their hazardous status through treatment alone (the 'derived-from' and 'mixture' rules apply), while characteristic wastes are only hazardous when they exhibit the characteristic.