Hazardous Waste Determinations and
Knowledge of Process

• What is a hazardous waste determination?
• Who is responsible for making a hazardous waste determination?
• How is a hazardous waste determination made?
• How can knowledge be applied to determine if a waste is a characteristic waste?
• Can I always use knowledge?
• How frequently must a hazardous waste determination be made?
• What type of paperwork/recordkeeping is necessary with hazardous waste determinations?
• Appendix A - Characteristic Wastes - 40 CFR 261, Subpart C 
  • Ignitability: (40 CFR 261.21)
  • Corrosivity: (40 CFR 261.22)
  • Reactivity: (40 CFR 261.23)
  • Toxicity: (40 CFR 261.24)
• Appendix B -Metals and Volatile Organic Compounds, Pesticides, Semi-Volatile Organic Compounds and Herbicides

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This web page is designed to answer general questions and provide basic information on how to perform "hazardous waste determinations", including the use of "knowledge of process" in making such determinations. The information provided below applies to all generators of hazardous waste, including large quantity generators (LQGs), small quantity generators (SQGs), and conditionally exempt small quantity generators (CESQGs).

The hazardous waste determination requirements are found in Section 22a-449(c)-102(a)(1) of the Regulations of Connecticut State Agencies (RCSA), incorporating 40 CFR 262.11.

This web page is not intended to supersede applicable regulations.  It is your responsibility to comply with all applicable laws and regulations.

What is a hazardous waste determination?

A hazardous waste determination is a procedure used to determine whether a waste is a hazardous waste.

Who is responsible for making a hazardous waste determination?

Any person who generates a solid waste must determine if that waste is a hazardous waste. Generators are responsible for making hazardous waste determinations.

How is a hazardous waste determination made?

A generator should initially determine if his/her waste is excluded from regulation. Excluded wastes are found in 40 CFR 261.4. If your waste is not excluded by 40 CFR 261.4, then proceed to the next two steps to determine if the waste is a hazardous waste:

1. If your waste is not excluded, then you need to determine if it is a listed hazardous waste. Listed wastes include: a) wastes from non-specific sources, such as spent solvents ("F" wastes); b) source specific wastes, such as wastewater treatment system sludges from specific processes ("K" wastes); c) certain discarded commercial chemical products, off-spec materials, container residues or spill residues thereof ("P" or "U" wastes). The listed wastes are identified in 40 CFR 261.30 - 261.33. If your waste is identified in this Subpart, then you have a listed hazardous waste. If your waste is not identified on this list, then proceed to the next step.
2. If your waste is not excluded or listed, then you need to determine if it is a characteristic hazardous waste. A waste is a characteristic waste if it exhibits the properties of ignitability, corrosivity, reactivity, or toxicity as defined in 40 CFR 261, Subpart C. [See Appendix A and Appendix B of this web page for the definition of characteristic wastes.]

How do you determine if a waste is a characteristic waste?

This can either be done by:

1. testing the waste according to the methods set forth in Subpart C of 40 CFR part 261, or
2. applying knowledge of the hazardous characteristic(s) of the waste in light of the materials or the processes used ("knowledge of process").

How can knowledge be applied to determine if a waste is a characteristic waste?

In some cases, a generator can use his/her knowledge of a waste to make a determination as to whether the waste is a characteristic hazardous waste. In order to use knowledge to characterize the waste, the generator must consider the raw materials that constitute the waste or the process(es) that result in the waste being generated.

In considering the materials that make up the waste, the generator needs to examine the specific chemical and physical characteristics of the waste material. Information such as Material Safety Data Sheets (MSDSs) can be a helpful resource. However, while MSDSs can provide useful information regarding ignitability (flash point), corrosivity (pH), and reactivity, they tend to be less useful when it comes to identifying the toxic characteristics of waste. MSDSs are not required to list all of the ingredients in a certain material, but only those that make up greater than 1% of the total constituents of that material (0.1% if they are carcinogens). This means that a waste may contain a toxic constituent exceeding the regulatory limit (making it a hazardous waste), but this constituent may not necessarily be included on the MSDS. Generators should also be aware that MSDSs are representative of raw materials; the MSDS may not accurately represent a waste material that is generated by the use of a particular raw material.

In considering the process that generates the waste, the generator needs to ask himself/herself: How does the operation/process affect the waste? For example, does the process make the waste ... more concentrated? ... more dilute?... contain free liquids?... become contaminated? ...etc.

One critical factor in using knowledge to characterize waste is that the knowledge must be applied appropriately. In other words, the knowledge that is applied must be valid and verifiable. A generator should not just assume that a waste is non-hazardous without providing some type of supporting, verifiable information to justify that conclusion. Using knowledge of the waste to conduct a hazardous waste determination involves a well thought out process in which the waste materials or the process generating the waste are considered. It should be noted that, more often than not, it is easier to use knowledge of the waste to characterize it as hazardous than it is to characterize it as non-hazardous.

Can I always use knowledge?

No. In many cases knowledge alone is inadequate to properly characterize the waste, specifically in those cases where the waste is cross-contaminated or inherently non-homogeneous. If you are generating a waste and your knowledge of the waste is insufficient to completely and accurately characterize it, you will need to get the waste tested by a lab that is certified to perform the tests that need to be conducted on the waste. Generators that use knowledge of process in waste determinations must be able to demonstrate the basis for their claim.

How frequently must a hazardous waste determination be made?

An initial characterization must be done on each waste stream and a re-characterization must be performed at least every twelve months, or whenever there is a process change.  It is recommended that MSDSs and other "knowledge of process" information be specifically reviewed during re-characterizations to ensure that neither the raw materials nor the process associated with the waste have changed.

What type of paperwork/recordkeeping is necessary with hazardous waste determinations?

According to 40 CFR 262.40, a generator must keep records of any test results, waste analysis, or other determinations made in accordance with 40 CFR 262.11 for at least three years from the date that the waste was last sent to on-site or off-site treatment, storage, or disposal. Generators that use knowledge of process in waste determinations must be able to demonstrate the basis for this claim.

Appendix A - Characteristic Wastes - 40 CFR 261, Subpart C

Ignitability: (40 CFR 261.21)

A solid waste exhibits the characteristic of ignitability if a representative sample of the waste has any of the following properties:

1. It is a liquid, other than an aqueous solution containing less than 24 percent alcohol by volume and has a flash point less than 60 °C (140 °F), as determined by a Pensky-Martens Closed Cup Tester, using the test method specified in ASTM Standard D-93-79 or D-93-80 (incorporated by reference, see 40 CFR 260.11), or a Setaflash Closed Cup Tester, using the test method specified in ASTM Standard D-3278-78, or as determined by an equivalent test method approved by the Commissioner under procedures set forth in 40 CFR 260.20 and 40 CFR 260.21.
2. It is not a liquid and is capable, under standard temperature and pressure, of causing fire through friction, absorption or moisture or spontaneous chemical changes and, when ignited, burns so vigorously and persistently that it creates a hazard.
3. It is an ignitable compressed gas as defined in 49 CFR 173.300 and as determined by the test methods described in that regulation or equivalent test methods approved by the Commissioner under 40 CFR 260.20 and 40 CFR 260.21.
4. It is an oxidizer as defined in 49 CFR 173.151.

A solid waste that exhibits that characteristic of ignitability has the EPA Hazardous Waste Number of D001.

Corrosivity: (40 CFR 261.22)

A solid waste exhibits the characteristic of corrosivity if a representative sample of the waste has either of the following properties:

1. It is aqueous and has a pH less than or equal to 2 or greater than or equal to 12.5, as determined by a pH meter using EPA Method 9040C in "Test Methods for Evaluating Solid Waste, Physical/Chemical Methods", EPA Publication SW-846.
2. It is a liquid and corrodes steel (SAE 1020) at a rate greater than 6.35 mm (0.250 inch) per year at a test temperature of 55 °C (130 °F) as determined by EPA Method 1110A.

A solid waste that exhibits the characteristic of corrosivity has the EPA Hazardous Waste Number of D002.

Reactivity: (40 CFR 261.23)

A solid waste exhibits the characteristic of reactivity if a representative sample of the waste has any of the following properties:

1. It is normally unstable and readily undergoes violent change without detonating.
2. It reacts violently with water.
3. It forms potentially explosive mixtures with water.
4. When mixed with water, it generates toxic gases, vapors or fumes in a quantity sufficient to present a danger to human health or the environment.
5. It is a cyanide or sulfide bearing waste which, when exposed to pH conditions between 2 and 12.5, can generate toxic gases, vapors or fumes in a quantity sufficient to present a danger to human health or the environment.
6. It is capable of detonation or explosive reaction if it is subjected to a strong initiating source or if heated under confinement.
7. It is readily capable of detonation or explosive decomposition or reaction at standard temperature and pressure.
8. It is a forbidden explosive as defined in 49 CFR 173.51, or a Class A explosive as defined in 49 CFR 173.53, or a Class B explosive as defined in 49 CFR 173.88.

A solid waste that exhibits the characteristic of reactivity has the EPA Hazardous Waste Number of D003.

Toxicity: (40 CFR 261.24)

A solid waste exhibits the characteristic of toxicity if, using the Toxicity Characteristic Leaching Procedure (TCLP), EPA Test Method 1311 in "Test Methods for Evaluating Solid Waste, Physical/Chemical Methods," EPA Publication SW-846, the extract from a representative sample of the waste contains any of the contaminants listed below at the concentration equal to or greater than the respective value given in the tables. Where the waste contains less than 0.5 percent filterable solids, the waste itself, after filtering using the methodology outlined in Method 1311, is considered to be the extract for this purpose. A solid waste that exhibits the characteristic of toxicity has the EPA Hazardous Waste Number specified below which corresponds to the toxic contaminant causing it to be hazardous.

Appendix B -Metals and Volatile Organic Compounds, Pesticides, Semi-Volatile Organic Compounds and Herbicides

For further information, please contact the DEEP’s toll-free Compliance Assistance (COMPASS) hotline at 1-888-424-4193, or send us an email.