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Hazardous Waste Determination


This page will help you determine if a given waste material must be classified as hazardous. The rules are spelled out in the Resource Conservation and Recovery Act (RCRA), and in the large body of regulations developed by the Environmental Protection Agency to implement RCRA.

The importance of accurately making hazardous waste determinations cannot be overstated -- failing to correctly identify all hazardous waste is the most common violation of RCRA regulations. Plus, when determinations are not correctly made, there is an excellent chance that hazardous waste management rules are not being followed, which means additional violations and fines.

Please note that the regulations in your state may be different in some respects from the federal regulations. Consult the Hazardous Waste State Resource Locator to find more information on your state's hazardous waste regulations.

Outline of the six steps

EPA recommends that you follow a six step process to determine whether a waste is hazardous. The steps are listed below, expressed as a series of questions:

The steps are discussed in some detail in the following sections, with an emphasis on issues that would typically arise in the construction sector. Because the issues can get complicated, the sections also provide links to more detailed information.

Is it "solid waste"?

The first step in determining if a material is a hazardous waste is to determine whether it is classified as a "solid waste." The rules specify that a material cannot be a hazardous waste unless it is first determined to be a solid waste.

This is the first of many times when the RCRA rules can be confusing. "Solid" for RCRA purposes doesn't mean what it means to you and me. The regulatory usage of the term "solid" in this context is closer to the sense of the word "contained."

RCRA states:

"The term "solid waste" means any garbage, refuse, sludge from a waste treatment plant, water supply treatment plant, or air pollution control facility, and other discarded material including solid, liquid, semisolid or contained gaseous material ..." (US Code, Title 42, paragraph 6903, emphasis added).

So even gaseous material can, in some circumstances, qualify as a "solid waste."

Most materials of concern at construction sites will fall under the "other discarded material" category in the RCRA definition. So how can you recognize when material has been "discarded"? According to EPA usage, there are three types of "discarded" material:

  1. Abandoned

  2. Recycled

  3. Inherently waste-like

Abandoned: In simplest terms, a material is considered "abandoned" if you plan to get rid of it. It clearly applies to material you have already disposed of, or that you have incinerated. It also applies to material that is being accumulated, stored and treated for eventual disposal or incineration.

It's not hard to imagine situations in which a facility and an inspector might have a difference of opinion about whether some stored material is or is not a waste. Here are some of the questions the inspector might ask:

  1. Do you have a use for the material?

  2. Do you treat the material as if it was a valuable commodity?

  3. Do you plan to give it to someone else that has a use for it?

For example, suppose the inspector comes across a 5 gallon container of solvent that is rusted, corroded and sitting in a pool of water. Even if the solvent is a valuable commodity, the facility is not 'treating' it as such. They are treating it as waste. The inspector would be likely to consider it abandoned.

Recycled: Specific types of recycled materials are considered 'discarded' and are therefore solid waste.

A material is normally considered to be discarded if it is:

  • used in a manner constituting disposal

  • burned for energy recovery

  • reclaimed

  • accumulated speculatively

"Speculative accumulation" refers to all those piles of material that you fully intend to recycle, but haven't quite gotten around to. EPA will generally consider that your material is being "accumulated speculatively" if you cannot demonstrate a viable market for it, or if you have not recycled at least 75% of it in a given calendar year.

A material is also considered discarded if it is accumulated, stored or treated before recycling.

Please note that some materials that are reclaimed are not considered solid wastes under RCRA, even if they exhibit a characteristic of hazardous waste (like ignitability or corrosivity -- see below). These include:

  • commercial chemical products

  • sludges

  • by-products

Similarly, commercial chemical products that are speculatively accumulated are also not solid wastes under RCRA.

Inherently waste-like: Certain materials pose such a significant threat to human health that they are deemed "inherently waste-like" and are always considered solid wastes. A standard example is any material containing dioxins -- that is in fact the only example so far.

In case of dispute: It can sometimes happen that an inspector will consider that a particular material has been "discarded", and the facility will not agree. In such a case, the facility will have to submit appropriate documentation to the inspector. For example, if you are claiming that the material is a valuable commodity or has another use, you will need to show that you have a market for it, or that someone is actually taking and using it beneficially, etc.

Is it excluded?

The next step is to determine if the waste qualifies for an exclusion from RCRA regulation. Generally, this does not apply to the construction sector, but it is presented for purposes of completeness. There are four main avenues:

  • solid waste exclusion

  • solid waste variance

  • hazardous waste exclusion

  • recycling

Solid waste exclusion: There are some materials that are specifically excluded from the definition of "solid waste ." You can find a full listing in 40 CFR 261.4(a). Examples include domestic sewage, industrial wastewater regulated under the Clean Water Act, and a long list of materials from industrial and agricultural processes that have little to do with construction sites.

Solid waste variance: Another possible way to keep a particular material from being regulated under RCRA is to apply for a solid waste variance. This option applies to:

  • Materials accumulated speculatively without sufficient amounts recycled

  • Materials reclaimed and reused within original process

  • Materials incompletely reclaimed

In order to use these variances, you will have to submit documentation demonstrating your case. If your state is authorized to administer the variance program, send the documentation to the director of your state agency. Otherwise, send it to the EPA Regional Administrator. You can find the rules governing solid waste variances in sections 40 CFR 260.30, 40 CFR 260.31 and 40 CFR 260.33.

Hazardous waste exclusion: Even if a material is indeed a solid waste, and even if it does not qualify for a solid waste variance, the regulations provide yet another possibility for exclusion. The solid waste might be excluded from being considered a "hazardous waste" if it falls under any of the exemptions listed in the next subsection of the Code, 40 CFR 261.4(b).

Most of the hazardous waste exclusions listed in that subsection are not relevant to the construction sector, but here are two possibilities that may apply to you:

  1. Used Freon (see 261.4(b), paragraphs (11) and (12))

  2. Samples of solid waste collected for the purpose of testing and treatability studies (see 261.4(d),(e), and (f))

Is it listed?

The RCRA regulations include four lists of materials, designated with the letters F, K, P, and U. If the waste you are screening appears on the any of the lists, your task is done -- it's hazardous.

What distinguishes the lists?

The F- and K-lists cover process wastes -- materials that have been used in processes carried out in your facility. The P- and U-lists cover unused chemicals that are being discarded for various reasons; for example, they may be off-specification or expired, they may have been spilled and cleaned up, or they may be residues left in containers.

The distinction between the two process waste lists (F and K) lies in their specificity. The K-list deals with very specific processes that are typically carried out by one manufacturing sector only, such as organic chemical manufacturing or petroleum refining. The F-list covers general processes that might occur in a range of sectors, such as solvent use, metal finishing processes, and wood preserving.

The unused chemicals lists (P and U) differ in their degree of risk. P-listed wastes are "acutely toxic", meaning that they can cause death or irreversible illness at low doses. U-listed wastes are "toxic": they are still regarded as hazardous, but some of the more drastic regulations that apply to the P-list do not apply to U-listed wastes.

The P- and U-lists do not apply to manufactured articles that contain a P- or U-listed waste (e.g. mercury thermostats) or to products that contain more than one active ingredient. Such wastes might still be hazardous, but their hazard classification would fall under a different category (most likely the toxicity characteristic discussed in the next section).

Construction projects do not carry out manufacturing processes, and would not typically generate any K-listed materials.

The first five F-listed categories, F001 - F005, cover a range of solvents used in a variety of applications. A construction project might generate F-listed solvents such as acetone, methanol, toluene, xylene, and methylene chloride from departments such as:

  • metal cleaning, degreasing, or

  • painting

The rest of the F-list is not likely to apply to construction sites.

The P-list includes about 239 different "acutely toxic" substances, listed under about 135 different waste codes. (Some codes cover several substances.) None of these wastes are normally found at construction sites.

The U-list includes about 472 distinct materials, listed under about 247 different waste codes. (As with the P-list, the same code can refer to several different materials.) None of these wastes are normally found at construction sites.

Is it characteristic?

Designating hazardous materials by listing them explicitly is fine as far as it goes, but that strategy will never go far enough. There are many more materials used in commerce than could ever be covered in a manageable set of lists. Furthermore, some mixtures of materials can be just as hazardous as single materials, while others can be relatively benign. Given the astronomical number of possible combinations of materials, listing is not a practical way to account for mixtures.

To cope with these possibilities, RCRA provides another set of criteria for classifying a waste as hazardous. Whatever its composition, a waste is considered hazardous by RCRA if it exhibits any of four characteristics:

  • ignitability (D001)

  • corrosivity (D002)

  • reactivity (D003)

  • toxicity (D0xx, where xx represents two digits from 04 through 43, and denotes a specific toxic chemical)

They are discussed in greater detail below.

Note: Even if a waste has been determined to be a listed waste, it should also be evaluated to see if it also qualifies as a characteristic waste. Additional rules may apply to it in some cases.

Ignitable wastes pose hazards because they either catch fire readily themselves, or (in the case of strong oxidizers) promote fires.

A waste is considered "ignitable" under RCRA if it is:

  • a liquid with flash point under 140oF, or

  • a non-liquid, but susceptible to vigorous burning by friction, water absorption, or spontaneous chemical change, or

  • a flammable compressed gas, or

  • a strong oxidizer

(The "flash point" of a liquid is the temperature at which the vapor above a pool of liquid will catch fire under a standard set of conditions.)

Ignitable wastes commonly found at construction sites include:

  • cleaning/degreasing solvents (e.g., naptha, stoddard solvent, mineral spirits),

  • solvent contaminate shop towels,

  • waste paints/solvents (e.g., xylene (xylol), toluene (toluol), paint thinners),

  • waste fuels (gasoline and diesel), and

  • used oil contaminated with fuel or solvents.

The regulations covering the ignitability characteristic can be found in Title 40 of the Code of Federal Regulations, Part 261, Section 21 (40 CFR 261.21).

Corrosive wastes include liquids with pH less than 2 or greater than 12.5, or that corrode steel faster than a quarter-inch per year at 55°C.

Examples of common corrosive wastes occurring at construction sites include:

  • spent acid (e.g., sulfuric, hydrochloric acids) cleaning solutions,

  • spent alkaline (e.g., sodium hydroxide) cleaning solutions, and

  • battery acid removed from a battery (sulfuric acid).

The regulations covering the corrosivity characteristic can be found in Title 40 of the Code of Federal Regulations, Part 261, Section 22 (40 CFR 261.22).

Note that spent batteries are a special type of hazardous waste called Universal Waste, when they are recycled following specific procedures. Go to Universal Wastes.

Reactive wastes include:

  • materials that generate toxic gases in contact with water

  • wastes that contain cyanide or sulfide and can release toxic gases in contact with strong acids or bases

  • explosive materials, or materials that are explosive when heated

Other than explosives (e.g., demolition), generally, reactive wastes are not generated at construction sites.

The RCRA sense of toxicity is somewhat indirect. The concern is not so much with the toxic properties of the wastes themselves as with the extent to which toxic materials can leach out of the wastes if they are exposed to water in the environment.

To measure this potential, the rules specify a test called the Toxic Characteristic Leaching Procedure, or TCLP (EPA Method 1311). The test is designed to give some indication of how readily various materials would tend to leach into groundwater if the waste were placed in a landfill. One form of the test involves subjecting the waste to a mild acetic acid solution (about the strength of household vinegar) at room temperature for 18 hours. The solution is then tested for the presence of any of the so-called "D-listed" chemicals. For each of the chemicals, the RCRA rules specify a threshold level (concentration). If any of the chemicals is present in the solution at a concentration above its threshold level, the waste is considered a toxic hazardous waste.

This link will take you to the most recent available version of the complete D-list.

Common construction wastes that are considered by RCRA to have the toxicity characteristic include:

  • lead (found in paint waste),

  • mercury (found in mercury thermostats, tilt switches and fluorescent bulbs), and

  • soil contaminated with solvent, lead or other toxic chemicals.

Note that spent fluorescent bulbs and batteries are a special type of hazardous waste called Universal Waste, when they are managed according to specific procedures. Go to Universal Wastes.

Is it a mixture?

If a hazardous waste (e.g., solvent) and a non-hazardous waste (e.g., used oil) are mixed, the resulting mixture may inherit the hazardous classification. The rules are different for listed and characteristic wastes.

  • Mixing in any amount of a listed waste will cause the mixture to be considered hazardous.

  • Mixing in a characteristic waste will cause the mixture to become hazardous only if the mixture itself exhibits the characteristic (e.g., ignitable, toxic).

There are various exceptions and exemptions -- see, for example, the RCRA Orientation Manual listed in the More Resources section for additional information and references.

Is it derived from a hazardous waste?

Similar rules apply to wastes that are derived from listed or characteristic hazardous wastes as residues from waste treatment processes. Since most construction sites are not hazardous waste Treatment, Storage, and Disposal (TSD) sites (and thus should be sending all hazardous wastes to a licensed TSD facility), this consideration is unlikely to apply to them.

Empty Containers

RCRA regulations (40 CFR 261.7) allow a container that once held a non-acute hazardous waste to be considered empty and not subject to hazardous waste regulation when all waste that can be removed has been removed using common practices such as pouring, pumping, and aspirating. The regulations also specify that:

  • No more than 1 inch of residue can remain on the bottom of the container or the inner liner
  • No more than 3 percent (by weight) of the container’s total capacity (less than or equal to 119 gallons) can remain in the container; or no more than 0.3 percent (by weight) of the container’s total capacity (greater than 119 gallons) can remain in the container

A container that held a compressed gas hazardous waste is considered empty when the pressure in the container approaches atmospheric.

For containers that held acute hazardous waste, one of the following conditions must be met for it to be considered empty:

  • The container or the inner liner has been triple rinsed using a solvent capable of removing the material
  • The container or inner liner has been cleaned by another method documented in scientific literature or by tests conducted by the generator to achieve equivalent removal
  • The inner liner has been removed

More Resources

Hazardous Waste Generators. EPA page with links to hazardous waste rules, forms, and other useful resources.

Managing Your Hazardous Waste: A Guide for Small Businesses (EPA 530-K-19-001). This handbook provides an overview of the regulations to give you a basic understanding of your responsibilities when generating and managing hazardous waste.

Summary of Requirements for Very Small Quantity Generators (EPA 530-F-20-002). If you generate no more than 100 kg (220 lbs) of hazardous waste and no more than 1 kg (2.2 lbs) of acute hazardous waste per month, you are a VSQG. As a VSQG, you must comply with three basic waste management requirements.

Waste Analysis at Facilities That Generate, Treat, Store, and Dispose of Hazardous Wastes. Also known as the Waste Analysis Plan (WAP) Guidance, this document is used to provide guidance on how to develop and implement WAPs suitable for managing hazardous wastes in accordance with the Resource Conservation and Recovery Act (RCRA).

RCRA Orientation Manual. This manual provides introductory information on the solid and hazardous waste management programs under the Resource Conservation and Recovery Act (RCRA).

Managing Used Oil Advice for Small Businesses. This fact sheet contains valuable information for businesses such as construction sites that generate and handle used oil. It summarizes the U.S. Environmental Protection Agency's (EPA's) used oil management standards - a set of "good housekeeping" requirements for used oil handlers.

Aerosol Can Universal Waste Rule. On December 9, 2019, the U.S. Environmental Protection Agency (EPA) finalized a rule to add aerosol cans to the federal universal waste program to provide an alternative, streamlined standard to manage widely generated hazardous wastes.


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