III-5

Managing Hazardous Waste—RCRA Subtitle C SECTION III SECTION III

Chapter 1: Hazardous Waste Identification

CHAPTER 1

HAZARDOUS WASTE IDENTIFICATION

OVERVIEW

What is a hazardous waste? Simply defined, a

hazardous waste is a waste with properties that

make it dangerous or capable of having a harmful

effect on human health or the environment.

Unfortunately, in order to develop a regulatory

framework capable of ensuring adequate

protection, this simple narrative definition is not

enough. Determining what is a hazardous waste is

paramount, because only those wastes that have

specific attributes are subject to Subtitle C

regulation.

Making this determination is a complex task

which is a central component of the hazardous

waste management regulations. Hazardous waste

is generated from many sources, ranging from

industrial manufacturing process wastes, to

batteries, to fluorescent light bulbs. Hazardous

waste may come in many forms, including liquids,

solids, gases, and sludges. To cover this wide

range, EPA has developed a system to identify

specific substances known to be hazardous and

provide objective criteria for including other

materials in this universe. Further complicating

matters, the regulations contain guidelines for

determining what exactly is a waste (called a solid

waste) and what is excluded from the hazardous

waste regulations, even though it otherwise is a

solid and hazardous waste. Finally, to promote

recycling and the reduction of the amount of waste

entering the RCRA system, EPA provides

exemptions for certain wastes when they are

recycled in certain manners.

In this chapter...

Overview........................................................... III-5

Hazardous Waste Identification Process .......... III-6

Is the Material a Solid Waste? .......................... III-6

- Recycled Materials ........................................ III-7

- Secondary Materials ..................................... III-9

- Sham Recycling ............................................ III-11

Is the Waste Excluded? .................................... III-11

- Solid Waste Exclusions ................................. III-12

- Hazardous Waste Exemptions ...................... III-15

- Raw Material, Product Storage, and Process

Unit Waste Exclusions .................................. III-17

- Sample and Treatability Study Exemptions ... III-18

Is the Waste a Listed Hazardous Waste?......... III-18

- Listing Criteria ............................................... III-18

- Hazardous Waste Listings ............................. III-19

- Delistings ....................................................... III-23

Is the Waste a Characteristic Hazardous

Waste? ............................................................. III-23

- Ignitability ...................................................... III-24

- Corrosivity ..................................................... III-24

- Reactivity ....................................................... III-25

- Toxicity........................................................... III-25

Special Regulatory Conventions ...................... III-26

- Mixture Rule .................................................. III-26

- Derived-From Rule ........................................ III-27

- Contained-In Policy ....................................... III-28

Hazardous Waste Identification Rules.............. III-29

Mixed Waste ..................................................... III-30

Summary .......................................................... III-30
III-6

 SECTION III SECTION III Managing Hazardous Waste—RCRA Subtitle C

Chapter 1: Hazardous Waste Identification

This chapter introduces the hazardous waste

identification process, describes how to determine

if a waste is a solid waste, and provides the

regulatory definition for hazardous waste. It also

discusses those wastes specifically excluded from

Subtitle C regulation, and those wastes exempted

when recycled.

HAZARDOUS WASTE

IDENTIFICATION PROCESS

Proper hazardous waste identification is

essential to the success of the RCRA program.

This identification process can be a very complex

task. Therefore, it is best to approach the issue by

asking a series of questions in a step-wise manner

(see Figure III-2). If facility owners and operators

answer the following questions, they can

determine if they are producing a hazardous

waste:

1. Is the material in question a solid waste?

2. Is the material excluded from the definition of

solid waste or hazardous waste?

3. Is the waste a listed hazardous waste? (Or, is

the waste delisted?)

4. Is the waste a characteristic hazardous waste?

This chapter will examine these key questions.

IS THE MATERIAL A SOLID WASTE?

The Subtitle C program uses the term solid

waste to denote something that is a waste. In

order for a material to be classified as a hazardous

waste, it must first be a solid waste. Therefore, the

first step in the hazardous waste identification

process is determining if a material is a solid

waste.

The statutory definition points out that

whether a material is a solid waste is not based on

the physical form of the material (i.e., whether or

not it is a solid as opposed to a liquid or gas), but

rather that the material is a waste. The regulations

Is material a

solid waste?

WASTE IS SUBJECT TO RCRA 

SUBTITLE C REGULATION

Yes

Is waste excluded from 

the definition of solid or 

hazardous waste?

Is waste a listed or characteristic 

hazardous waste?

MATERIAL IS NOT 

SUBJECT TO 

RCRA SUBTITLE 

C REGULATION

Is waste delisted?

No

Yes

Yes

No

No

Yes

No

Figure III-2: HAZARDOUS WASTE IDENTIFICATION PROCESS
III-7

Managing Hazardous Waste—RCRA Subtitle C SECTION III SECTION III

Chapter 1: Hazardous Waste Identification

further define solid waste as any material that is

discarded by being either abandoned, inherently

waste-like, a certain military munition, or recycled

(see Figure III-3).

• Abandoned — The term abandoned simply

means thrown away. A material is abandoned

if it is disposed of, burned, or incinerated.

• Inherently Waste-Like — Some materials pose

such a threat to human health and the

environment that they are always considered

solid wastes; these materials are considered to

be inherently waste-like. Examples of

inherently waste-like materials include certain

dioxin-containing wastes.

• Military Munition — Military munitions are

all ammunition products and components

produced for or used by the U.S. Department

of Defense (DOD) or U.S. Armed Services for

national defense and security. Unused or

defective munitions are solid wastes when

abandoned (i.e., disposed of, burned,

incinerated) or treated prior to disposal;

rendered nonrecyclable or nonuseable

through deterioration; or declared a waste by

an authorized military official. Used (i.e., fired

or detonated) munitions may also be solid

wastes if collected for storage, recycling,

treatment, or disposal.

• Recycled — A material is recycled if it is used

or reused (e.g., as an ingredient in a process),

or reclaimed. A material is reclaimed if it is

processed to recover a usable product (e.g.,

smelting a waste to recover valuable metal

constituents), or if it is regenerated though

processing to remove contaminants in a way

that restores them to their useable condition

(e.g., distilling dirty spent solvents to produce

clean solvents). (Recycled materials are fully

discussed in Section III, Chapter 2.)

■ Recycled Materials

Materials that are recycled are a special subset

of the solid waste universe. When recycled, some

materials are not solid wastes, and therefore, not

hazardous wastes, while others are solid and

hazardous waste, but are subject to less-stringent

regulatory controls. The level of regulation that

applies to recycled materials depends on the

Is material discarded by being either:

1) Abandoned;

2) Inherently waste-like;

3) A discarded military munition; or

4) Recycled?

MATERIAL IS A SOLID WASTE 

AND MAY BE A HAZARDOUS 

WASTE SUBJECT TO RCRA 

SUBTITLE C REGULATION

Yes

No

MATERIAL IS NOT A 

SOLID WASTE AND IS 

NOT SUBJECT TO 

RCRA SUBTITLE C 

REGULATION

Figure III-3: IS IT A SOLID WASTE?
III-8

 SECTION III SECTION III Managing Hazardous Waste—RCRA Subtitle C

Chapter 1: Hazardous Waste Identification

material and the type of recycling (see Figure

III-4). Because some types of recycling pose

threats to human health and the environment,

RCRA does not exempt all recycled materials from

the definition of solid waste. As a result, the

manner in which a material is recycled will

determine whether or not the material is a solid

waste, and therefore potentially regulated as a

hazardous waste. In order to encourage waste

recycling, RCRA exempts three types of wastes

from the definition of solid waste:

• Wastes Used as an Ingredient — If a material

is directly used as an ingredient in a

production process without first being

reclaimed, then that material is not a solid

waste.

• Wastes Used as a Product Substitute — If a

material is directly used as an effective

substitute for a commercial product (without

first being reclaimed), it is exempt from the

definition of solid waste.

• Wastes Returned to the Production Process —

When a material is returned directly to the

production process (without first being

reclaimed) for use as a feedstock or raw

material, it is not a solid waste.

Conversely, materials are solid wastes, and are

not exempt, if they are recycled in certain ways. If

these materials are used in a manner constituting

disposal; burned for energy recovery, used to

produce a fuel, or contained in fuels; accumulated

Is waste recycled by being:

1) Used as an ingredient; 

2) Used as a product substitute; or

3) Returned to the production process?

Is recycled waste:

1) Used in a manner constituting disposal; 

2) Burned for energy recovery, used to 

 produce a fuel, or contained in fuels; 

3) Accumulated speculatively; or

4) A dioxin-containing waste considered

 inherently waste-like?

No

WASTE IS A SOLID WASTE

No

WASTE IS NOT A SOLID WASTE

Yes

Facility must determine if waste is a:

1) Spent material; 

2) Sludge; 

3) By-product;

4) Commercial chemical product; or

5) Scrap metal

Is waste reclaimed?

Yes

Yes

Figure III-4: ARE ALL RECYCLED WASTES SOLID WASTES?
III-9

Managing Hazardous Waste—RCRA Subtitle C SECTION III SECTION III

Chapter 1: Hazardous Waste Identification

and not simply stored to avoid regulation, EPA

established a provision to encourage facilities

to recycle sufficient amounts in a timely

manner. This provision designates as solid

wastes those materials that are accumulated

speculatively. A material is accumulated

speculatively (e.g., stored in lieu of

expeditious recycling) if it has no viable

market or if the person accumulating the

material cannot demonstrate that at least 75

percent of the material is recycled in a

calendar year, commencing on January 1 (see

Figure III-5).

• Dioxin-Containing Wastes Considered

Inherently Waste-Like — Dioxin-containing

wastes are considered inherently waste-like

because they pose significant threats to human

health and the environment if released or

mismanaged. As a result, RCRA does not

exempt such wastes from the definition of

solid waste even if they are recycled through

direct use or reuse without prior reclamation.

This is to ensure that such wastes are subject

to the most protective regulatory controls.

speculatively; or dioxin-containing wastes

considered inherently waste-like; then they are

defined as solid wastes.

• Used in a Manner Constituting Disposal —

Use constituting disposal is the direct

placement of wastes or products containing

wastes (e.g., asphalt with petroleum-refining

wastes as an ingredient) on the land.

• Burned for Energy Recovery, Used to Produce

a Fuel, or Contained in Fuels — Burning

hazardous waste for fuel (e.g., burning for

energy recovery) and using wastes to produce

fuels are regulated activities. Conversely,

commercial products intended to be burned

as fuels are not considered solid wastes. For

example, off-specification jet fuel (e.g., a fuel

with minor chemical impurities) is not a solid

waste when it is burned for energy recovery,

because it is itself a fuel.

• Accumulated Speculatively — In order to

encourage recycling of wastes as well as

ensure that materials are actually recycled,

Figure III-5: MATERIALS ACCUMULATED SPECULATIVELY

1 2 56 3 4 7

29

1 2 56 3 4 7

29

1 2 56 3 4 7

29

1 2 56 3 4 7

29

1 2 56 3 4 7

29

1 2 56 3 4 7

29

1 2 56 3 4 7

29

1 2 56 3 4 7

29

1 2 56 3 4 7

December 1998

8 9 12 13 14 10 11

15 16 19 20 21 17 18

22 23 26 2 24 25 7 28

29 30 31

1 2 56 3 4 7

January 1998

8 9 12 13 14 10 11

15 16 19 20 21 17 18

22 23 26 2 24 25 7 28

29 30 31

200 lbs. of recyclable material in 

storage

150 lbs. of the same recyclable 

material still in storage

On January 1, 1998, a facility has 200 lbs. of a material that it wants to re-insert directly into its production process. Such a 

material is technically exempt from the definition of solid waste because it is being recycled through direct reuse without prior 

reclamation. However, by the end of the calendar year (December 31, 1998), less than 75 percent (i.e., less than 150 lbs.) of the 

material has been reclaimed or sent off site for reclamation. Therefore, the material has been speculatively accumulated and is 

no longer exempt from the definition of solid waste. The material may then be regulated as a hazardous waste.
III-10

 SECTION III SECTION III Managing Hazardous Waste—RCRA Subtitle C

Chapter 1: Hazardous Waste Identification

Spent Materials

Spent materials are materials that have been

used and can no longer serve the purpose for

which they were produced without processing.

For example, a solvent used to degrease metal

parts will eventually become contaminated such

that it cannot be used as a solvent until it is

regenerated. If a spent material must be

reclaimed, it is a solid waste and is subject to

hazardous waste regulation. Spent materials are

also regulated as solid wastes when used in a

manner constituting disposal; burned for energy

recovery, used to produce a fuel, or contained in

fuels; or accumulated speculatively (see Figure

III-6).

■ Secondary Materials

Not all materials can be directly used or

reused without reclamation. If such materials

need to be reclaimed before use, they are

generally regulated as solid wastes. However,

some materials that must be reclaimed prior to use

as a recyclable material may still be exempt from

the definition of solid waste. This depends on the

type of material that the waste is. In order to

facilitate this solid waste determination process,

EPA groups all materials into five categories.

These secondary materials consist of spent

materials, sludges, by-products, commercial

chemical products (CCPs), and scrap metal.

Figure III-6: REGULATORY STATUS OF SECONDARY MATERIALS

These materials are solid wastes when...

Spent Materials

Reclaimed

Used in a manner 

constituting 

disposal

Burned for energy 

recovery, used to produce 

a fuel, or contained in fuels

Accumulated 

speculatively

Listed Sludges

Characteristic Sludges

Listed By-products

Commercial Chemical Products

* If such management is consistent with the product’s normal use, then commercial chemical products used in a 

manner constituting disposal or burned for energy recovery, used to produce a fuel, or contained in fuels are not 

solid wastes. 

√ Material is a solid waste

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√ √

* *

Characteristic By-products

Scrap Metal
III-11

Managing Hazardous Waste—RCRA Subtitle C SECTION III SECTION III

Chapter 1: Hazardous Waste Identification

Sludges

Sludges are any solid, semisolid, or liquid

wastes generated from a wastewater treatment

plant, water supply treatment plant, or air

pollution control device (e.g., filters, baghouse

dust). Sludges from specific industrial processes or

sources (known as listed sludges) are solid wastes

when reclaimed; used in a manner constituting

disposal; burned for energy recovery, used to

produce a fuel, or contained in fuels; or

accumulated speculatively. On the other hand,

characteristic sludges (which are sludges that

exhibit certain physical or chemical properties) are

not solid wastes when reclaimed, unless they are

used in a manner constituting disposal; burned for

energy recovery, used to produce a fuel, or

contained in fuels; or accumulated speculatively

(see Figure III-6). (Listings and characteristics are

fully discussed later in this chapter.)

By-Products

By-products are materials that are not one of

the intended products of a production process.

An example is the sediment remaining at the

bottom of a distillation column. By-product is a

catch-all term and includes most wastes that are

not spent materials or sludges. Listed by-products

are solid wastes when reclaimed; used in a

manner constituting disposal; burned for energy

recovery, used to produce a fuel, or contained in

fuels; or accumulated speculatively. On the other

hand, characteristic by-products are not solid

wastes when reclaimed, unless they are used in a

manner constituting disposal; burned for energy

recovery, used to produce a fuel, or contained in

fuels; or accumulated speculatively (see Figure

III-6).

Commercial Chemical Products

Commercial chemical products are unused

or off-specification chemicals (e.g., chemicals that

have exceeded their shelf life), spill or container

residues, and other unused manufactured

products that are not typically considered

chemicals. CCPs are not solid wastes when

reclaimed, unless they are used in a manner

constituting disposal; or burned for energy

recovery, used to produce a fuel, or contained in

fuels (see Figure III-6).

Scrap Metal

Scrap metal is worn or extra bits and pieces of

metal parts, such as scrap piping and wire, or

worn metal items, such as scrap automobile parts

and radiators. If scrap metal must be reclaimed, it

is a solid waste and is subject to hazardous waste

regulation. Scrap metal is also regulated as a solid

waste when used in a manner constituting

disposal; burned for energy recovery, used to

produce a fuel, or contained in fuels; or

accumulated speculatively. This does not apply to

processed scrap metal which is excluded from

hazardous waste generation entirely (as discussed

later in this chapter).

■ Sham Recycling

For all recycling activities, the above rules are

based on the premise that legitimate reclamation

or reuse is taking place. EPA rewards facilities

recycling some wastes by exempting them from

regulation, or by subjecting them to lesser

regulation. Some facilities, however, may claim

that they are recycling a material in order to avoid

being subject to RCRA regulation, when in fact the

activity is not legitimate recycling. EPA has

established guidelines for what constitutes

legitimate recycling and has described activities it

considers to be illegitimate or sham recycling.

Considerations in making this determination

include whether the secondary material is

effective for the claimed use, if the secondary

material is used in excess of the amount necessary,

and whether or not the facility has maintained

records of the recycling transactions.
III-12

 SECTION III SECTION III Managing Hazardous Waste—RCRA Subtitle C

Chapter 1: Hazardous Waste Identification

• Exclusions for waste generated in raw material,

product storage, or manufacturing units

• Exclusions for laboratory samples and waste

treatability studies.

If the waste fits one of these categories, it is

not regulated as a RCRA hazardous waste, and the

hazardous waste requirements do not apply.

■ Solid Waste Exclusions

A material cannot be a hazardous waste if it

does not meet the definition of a solid waste.

Thus, wastes that are excluded from the definition

of solid waste are not subject to RCRA Subtitle C

hazardous waste regulation. There are 15

exclusions from the definition of solid waste.

Domestic Sewage and Mixtures of Domestic

Sewage

Domestic sewage, or sanitary waste, comes

from households, office buildings, factories, and

any other place where people live and work.

These wastes are carried by sewer to a municipal

wastewater treatment plant (called a publicly

owned treatment works (POTW)). The treatment

of these wastes is regulated under the Clean Water

Act (CWA). Mixtures of sanitary wastes and other

wastes (including hazardous industrial wastes) that

IS THE WASTE EXCLUDED?

Not all RCRA solid wastes qualify as hazardous

wastes. Other factors must be considered before

deciding whether a solid waste should be

regulated as a hazardous waste. Regulation of

certain wastes may be impractical or otherwise

undesirable, regardless of the hazards that the

waste might pose. For instance, household waste

can contain dangerous chemicals, such as solvents

and pesticides, but subjecting households to the

strict RCRA waste management regulations would

create a number of practical problems. As a

result, Congress and EPA exempted or excluded

certain wastes, such as household wastes, from the

hazardous waste definition and regulations.

Determining whether or not a waste is excluded

or exempted from hazardous waste regulation is

the second step in the RCRA hazardous waste

identification process. There are four categories of

exclusions:

• Exclusions from the definition of solid waste

• Exclusions from the definition of hazardous

waste

National 

Pollutant 

Discharge 

Elimination 

System 

Discharge

Surface Waters of 

the United States

Clean Water Act 

Pretreatment Surface 

Impoundments

SHAM RECYCLING

Sham recycling may include situations when a

secondary material is:

• Ineffective or only marginally effective for the

claimed use (e.g., using certain heavy metal

sludges in concrete when such sludges do not

contribute any significant element to the

concrete’s properties)

• Used in excess of the amount necessary (e.g.,

using materials containing chlorine as an

ingredient in a process requiring chlorine, but in

excess of the required chlorine levels)

• Handled in a manner inconsistent with its use as a

raw material or commercial product substitute

(e.g., storing materials in a leaking surface

impoundment as compared to a tank in good

condition that is intended for storing raw

materials).
III-13

Managing Hazardous Waste—RCRA Subtitle C SECTION III SECTION III

Chapter 1: Hazardous Waste Identification

pass through a sewer system to a POTW are also

excluded from Subtitle C regulation once they

enter the sewer.

Industrial Wastewater Discharges (Point Source

Discharges)

Another exclusion from RCRA designed to

avoid overlap with CWA regulations applies to

point source discharges. Point source discharges

are discharges of pollutants (e.g., from a pipe,

sewer, or pond) directly into a lake, river, stream,

or other water body. CWA regulates such

discharges under the National Pollutant Discharge

Elimination System (NPDES) permitting program.

Under this exclusion from the definition of solid

waste, wastewaters that are subject to CWA

regulations are exempt from Subtitle C regulation

at the point of discharge. Any hazardous waste

generation, treatment, or storage prior to the

discharge is subject to RCRA regulation. Many

industrial facilities that treat wastewater on site

utilize this point source discharge exclusion.

Irrigation Return Flows

When farmers irrigate agricultural land, water

not absorbed into the ground can flow into

reservoirs for reuse. This return flow often picks

up pesticide or fertilizer constituents, potentially

rendering it hazardous. Because this water may

be reused on the fields, it is excluded from the

definition of solid waste.

Radioactive Waste

Radioactive waste is regulated by either the

Nuclear Regulatory

Commission or the U.S.

Department of Energy

(DOE) under the

Atomic Energy Act

(AEA). To avoid

duplicative regulation

under RCRA and AEA,

RCRA excludes certain radioactive materials from

the definition of solid waste. However, RCRA

excludes only the radioactive components of the

waste. If a radioactive waste is mixed with a

hazardous waste, the resultant mixture is regulated

by both AEA and RCRA as a mixed waste.

Similarly, if a facility generates a hazardous waste

that is also radioactive, the material is a mixed

waste and is subject to regulation under both

RCRA and AEA (the regulatory status of mixed

waste is fully discussed later in this chapter).

In-Situ Mining Waste

In-situ (in-place) mining of certain minerals

may involve the application of solvent solutions

directly to a mineral deposit in the ground. The

solvent passes through the ground, collecting the

mineral as it moves. The mineral and solvent

mixtures are then collected in underground wells

where the solution is removed. Such solventcontaminated earth, or any nonrecovered solvent,

is excluded from the definition of solid waste

when left in place.

Pulping Liquors

Pulping liquor, also called black liquor, is a

corrosive material used to dissolve wood chips for

manufacturing of paper and other materials. To

promote waste minimization and recycling, EPA

excluded pulping liquors from the definition of

solid waste if they are reclaimed in a recovery

furnace and then reused in the pulping process. If

the liquors are recycled in another way, or are

accumulated speculatively, they are not excluded.

Spent Sulfuric Acid

Spent sulfuric acid may be recycled to

produce virgin sulfuric acid. To promote waste

reduction and recycling, such recycled spent

sulfuric acid is excluded from the definition of

solid waste, unless the facility accumulates the

material speculatively.
III-14

 SECTION III SECTION III Managing Hazardous Waste—RCRA Subtitle C

Chapter 1: Hazardous Waste Identification

Closed-Loop Recycling

To further promote waste reduction and

recycling, spent materials that are reclaimed and

returned to the original process in an enclosed

system of pipes and tanks are excluded from the

definition of solid waste, provided that:

• Only tank storage is involved, and the entire

process, through reclamation, is closed to the

air (i.e., enclosed)

• Reclamation does not involve controlled flame

combustion, such as that which occurs in

boilers, industrial furnaces, or incinerators

• Waste materials are never accumulated in

tanks for more than 12 months without being

reclaimed

• Reclaimed materials are not used to produce a

fuel, or used to produce products that are

used in a manner constituting disposal.

An example of such a closed-loop system

might include a closed solvent recovery system in

which the dirty solvents are piped from the

degreasing unit to a solvent still where the solvent

is cleaned, and then piped back to the degreasing

unit.

Spent Wood Preservatives

Many wood preserving plants recycle their

wastewaters and spent wood preserving solutions.

These materials are collected on drip pads and

sumps, and are in many cases returned directly to

the beginning of the wood preserving process

where they are reused in the same manner. While

the process resembles a closed-loop recycling

process, the closed-loop recycling exclusion does

not apply because drip pads are open to the air.

Consistent with their objective to encourage

recycling hazardous waste, EPA developed two

specific exclusions for spent wood preserving

solutions and wastewaters containing spent

preservatives, provided that the materials have

been reclaimed and are reused for their original

purpose. In addition, EPA proposed to exclude

wood preserving solutions and wastewaters from

the definition of solid waste prior to reclamation.

In order to use this proposed exclusion, a facility

would be required to reuse the materials for their

intended purpose, and manage them in a way that

prevented releases to the environment.

Coke By-Product Wastes

Coke, used in the production of iron, is made

by heating coal in high temperature ovens.

Throughout the production process many byproducts are created. The refinement of these

coke by-products generates several listed and

characteristic wastestreams. However, to promote

recycling of these wastes, EPA provided an

exclusion from the definition of solid waste for

certain coke by-product wastes that are recycled

into new products.

Splash Condenser Dross Residue

The treatment of steel production pollution

control sludge generates a zinc-laden residue,

called a dross. This material, generated from a

splash condenser in a high temperature metal

recovery process, is known as a splash condenser

dross residue. Because this material contains 50

to 60 percent zinc, it is often reclaimed, reused, or

processed as a valuable recyclable material. Since

facilities commonly handle this material as a

valuable commodity by managing it in a way that

is protective of human health and the

environment, EPA excluded this residue from the

definition of solid waste.
III-15

Managing Hazardous Waste—RCRA Subtitle C SECTION III SECTION III

Chapter 1: Hazardous Waste Identification

Recovered Oil From Petroleum Refining

Operations

Petroleum refining facilities sometimes recover

oil from oily wastewaters and reuse this oil in the

refining process. In order to encourage waste

minimization and recycling, EPA excluded such

recovered oil from the definition of solid waste

when it is returned to the refinery.

Comparable Fuels

In order to promote the recycling of materials

with high fuel values, certain materials that are

burned as fuels are excluded from the definition

of solid waste, provided that they meet certain

specifications (i.e., are of a certain degree of

purity). This is to ensure that the material does

not exceed certain levels of toxic constituents and

physical properties that might impede burning.

Materials that meet this specification are

considered comparable to pure or virgin fuels.

Processed Scrap Metal

Scrap metal includes, but is not limited to,

pipes, containers, equipment, wire, and other

metal items that are no longer of use. To facilitate

recycling, scrap metal that has been processed to

make it easier to handle or transport and is sent

for metals recovery is excluded from the definition

of solid waste.

Shredded Circuit Boards

Circuit boards are metal boards that hold

computer chips, thermostats, batteries, and other

electronic components. Circuit boards can be

found in computers, televisions, radios, and other

electronic equipment. When this equipment is

thrown away, these boards can be removed and

recycled. Whole circuit boards meet the

definition of scrap metal, and are therefore

exempt from hazardous waste regulation when

recycled (as discussed in Section III, Chapter 2).

On the other hand, some recycling processes

involve shredding the board. Such shredded

boards do not meet the exclusion for recycled

scrap metal. In order to facilitate the recycling of

such materials, EPA excluded recycled shredded

circuit boards from the definition of solid waste,

provided that they are stored in containers

sufficient to prevent release to the environment,

and are free of potentially dangerous components,

such as mercury switches, mercury relays, nickelcadmium batteries, and lithium batteries.

■ Hazardous Waste

Exemptions

EPA also exempts certain

solid wastes from the definition

of hazardous waste. If a

material meets an exemption

from the definition of hazardous waste, it cannot

be a hazardous waste, even if the material

technically meets a listing or exhibits a

characteristic. There are 13 exemptions from the

definition of hazardous waste.

Household Hazardous Waste

Households often generate solid wastes that

could technically be hazardous wastes (e.g., old

solvents, paints, pesticides, fertilizer, poisons).

However, it would be impossible to regulate every

house in the United States that occasionally threw

away a can of paint thinner or a bottle of rat

poison. Therefore, EPA developed the household

waste exemption. Under this exemption, wastes

generated by normal household activities (e.g.,

routine house and yard maintenance) are exempt

from the definition of hazardous waste. EPA has

expanded the exemption to include householdlike areas, such as bunkhouses, ranger stations,

crew quarters, campgrounds, picnic grounds, and

day-use recreation areas. While household

hazardous waste is exempt from Subtitle C, it is

regulated under Subtitle D as a solid waste (as

discussed in Section II).
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Agricultural Waste

To prevent overregulation of farms and

promote waste recycling, solid wastes generated

by crop or animal farming are excluded from the

definition of hazardous waste provided that the

wastes are returned to the ground as fertilizers or

soil conditioners. Examples of such wastes are

crop residues and manures.

Mining Overburden

After an area of a surface mine has been

depleted, it is common practice to return to the

mine the earth and rocks (overburden) that were

removed to gain access to ore deposits. When the

material is returned to the mine site, it is not a

hazardous waste under RCRA.

Bevill and Bentsen Wastes

In the Solid Waste Disposal Act Amendments

of 1980, Congress amended RCRA by exempting

oil, gas, and geothermal exploration,

development, and production wastes (Bentsen

wastes); fossil fuel combustion wastes; mining and

mineral processing wastes; and cement kiln dust

wastes (Bevill wastes) from the definition of

hazardous waste pending further study by EPA.

These wastes were temporarily exempted because

they were produced in very large volumes, were

thought to pose less of a hazard than other wastes,

and were generally not amenable to the

management practices required under RCRA. The

following paragraphs describe these exemptions in

detail.

Fossil Fuel Combustion Waste

In order to accommodate effective study, fossil

fuel combustion wastes were divided into two

categories, large-volume coal-fired utility wastes

and remaining wastes. After studying these

wastes, in 1993, EPA decided to permanently

exempt large-volume coal-fired utility wastes,

including fly ash, bottom ash, boiler slag, and flue

gas emission control waste from the definition of

hazardous waste. EPA continues to study the

remaining wastes. Until a final determination is

made, these wastes will remain exempt. The

remaining waste category includes, but is not

limited to, wastes from utilities burning other

noncoal fossil fuels and wastes from nonutility

boilers burning any type of fossil fuel.

Oil, Gas, and Geothermal Wastes

Certain wastes from the exploration and

production of oil, gas, and geothermal energy are

excluded from the definition of hazardous waste.

These wastes include those that have been

brought to the surface during oil

and gas exploration and

production operations, and

other wastes that have

come into contact with the

oil and gas production

stream (e.g., during

removal of waters injected

into the drill well to cool

the drill bit).

Mining and Mineral Processing Wastes

 Certain wastes from the mining, refining, and

processing of ores and minerals are excluded from

the definition of hazardous waste.

Cement Kiln Dust

Cement kiln dust is a fine-grained solid byproduct generated during the cement

manufacturing process and captured in a facility’s

air pollution control system. After study, EPA

decided to develop specific regulatory provisions

for cement kiln dust. Until EPA promulgates these

new regulatory controls, however, cement kiln

dust will generally remain exempt from the

definition of hazardous waste.
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Trivalent Chromium Wastes

The element chromium exists in two forms,

hexavalent and trivalent. EPA determined that

while hexavalent chromium poses enough of a

threat to merit regulation as a characteristic

hazardous waste, trivalent chromium does not.

Therefore, to prevent unnecessary regulation, EPA

excluded, from the definition of hazardous waste,

trivalent chromium-bearing hazardous wastes from

certain leather tanning, shoe manufacturing, and

leather manufacturing industries.

Arsenically Treated Wood

Discarded arsenically treated wood or wood

products that are hazardous only because they

exhibit certain toxic characteristics (e.g., contain

harmful concentrations of metal or pesticide

constituents), are excluded from the definition of

hazardous waste. Once such treated wood is

used, it may be disposed of by the user

(commercial or residential) without being subject

to hazardous waste regulation. This exclusion is

based on the fact that the risks posed by the use of

such wood products on the land is identical to

those posed by the wood’s disposal. For example,

arsenically treated telephone poles that are used

as products on the land pose risks similar to the

disposal of such poles. This exclusion applies only

to end-users and not to manufacturers.

Petroleum-Contaminated Media and Debris

from Underground Storage Tanks

USTs are used to store petroleum (e.g., oil)

and hazardous substances (e.g., ammonia). When

these tanks leak, the UST program under RCRA

Subtitle I provides requirements for cleaning up

such spills (the regulatory requirements for USTs

are fully discussed in Section IV). To facilitate the

corrective action process under the UST

regulations, contaminated media (soils and ground

water) and debris (tanks and equipment) at sites

undergoing UST cleanup that are hazardous only

because they exhibit certain toxic characteristics

(e.g., contain a harmful concentrations of

leachable organic constituents) are excluded from

the definition of hazardous waste.

Spent Chlorofluorocarbon Refrigerants

Chlorofluorocarbons (CFCs) released to the

atmosphere damage the stratospheric ozone layer.

To promote recycling and discourage the practice

of venting used CFCs to the atmosphere as a

means of avoiding Subtitle C regulation, EPA

excluded recycled CFCs from the definition of

hazardous waste since the refrigerants are

generally reclaimed for reuse.

Used Oil Filters

In order to promote the

recycling and recovery of metals

and other products from used oil

filters, EPA exempted used oil

filters that have been properly

drained to remove the used oil.

Used Oil Distillation Bottoms

When used oil is recycled, residues (called

distillation bottoms) form at the bottom of the

recycling unit. To promote used oil recycling and

the beneficial reuse of waste materials, EPA

excluded these residues from the definition of

hazardous waste when the bottoms are used as

ingredients in asphalt paving and roofing

materials.

■ Raw Material, Product Storage, and

Process Unit Waste Exclusions

Hazardous wastes generated in raw material,

product storage, or process (e.g., manufacturing)

units are exempt from Subtitle C hazardous waste

regulation while the waste remains in such units.

These units include tanks, pipelines, vehicles, and

vessels used either in the manufacturing process or
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for storing raw materials or products, but

specifically do not include surface impoundments.

Once the waste is removed from the unit, or

when a unit temporarily or permanently ceases

operation for 90 days, the waste is considered

generated and is subject to regulation.

■ Sample and Treatability Study Exclusions

Hazardous waste samples are small, discrete

amounts of hazardous waste that are essential to

ensure accurate characterization and proper

hazardous waste treatment. In order to facilitate

the analysis of these materials, RCRA exempts

characterization samples and treatability study

samples from Subtitle C hazardous waste

regulation.

Waste Characterization Samples

Samples sent to a lab to determine whether or

not a waste is hazardous are exempt from

regulation. Such samples (typically less than one

gallon of waste) are excluded from Subtitle C

regulation, provided that these samples are

collected and shipped for the sole purpose of

determining hazardous waste characteristics or

composition. Storage, transportation,

and testing of the sample

are excluded from RCRA

regulation even when the lab

testing is complete, provided the sample is

returned to the generator, and other specific

provisions are met. When shipping the

sample to or from the laboratory, the sample

collector must comply with certain labeling

requirements, as well as any applicable U.S.

Postal Service (USPS) or U.S. Department of

Transportation (DOT) shipping requirements.

Treatability Study Samples

To determine if a particular treatment method

will be effective on a given waste or what types of

wastes remain after the treatment is complete,

facilities send samples of waste to a lab for testing.

EPA conditionally exempts those who generate or

collect samples for the sole purpose of conducting

treatability studies from the hazardous waste

regulations, provided that certain requirements,

including packaging, labeling, and recordkeeping

provisions, are met. In addition, under specific

conditions, laboratories conducting such

treatability studies may also be exempt from

Subtitle C regulation.

IS THE WASTE A LISTED HAZARDOUS

WASTE?

After a facility determines that its waste is a

solid waste and is not either excluded from the

definitions of solid or hazardous waste or exempt

from Subtitle C hazardous waste regulation, the

owner and operator must determine if the waste is

a hazardous waste. The first step in this process is

determining if the waste is a listed hazardous

waste. The hazardous waste listings consist of four

lists:

• The F list • The P list

• The K list • The U list.

Listed wastes are wastes from generic

industrial processes, wastes from certain sectors of

industry, and unused pure chemical products and

formulations. Because these wastes are dangerous

enough to warrant full Subtitle C regulation based

on their origin, any waste fitting a narrative listing

description is considered a listed hazardous waste.

■ Listing Criteria

Before developing each hazardous waste

listing, EPA thoroughly studies a particular

wastestream and the threats that it can pose to

human health and the environment. If the waste

poses enough of a threat, EPA includes a precise

description of that waste on one of four hazardous

waste lists within the regulations.
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■ Hazardous Waste Listings

EPA has applied the listing criteria to hundreds

of specific industrial wastestreams. These wastes

are grouped into the four lists located at 40 CFR

Part 261, Subpart D. Listed wastes are organized

as follows:

• The F list — The F list includes wastes from

certain common industrial and manufacturing

processes. Because the processes generating

these wastes can occur in different sectors of

industry, the F list wastes are known as wastes

from nonspecific sources. The F list is codified

in the regulations at 40 CFR §261.31.

In order to determine whether a waste should

be listed in the first place, the Agency developed a

set of criteria to use as a guide and a consistent

frame of reference when considering listing a

wastestream. EPA only uses these criteria when

evaluating whether to list a waste, as these listing

criteria cannot be used by waste handlers for

waste identification purposes. Waste handlers

must instead consult the actual listings to

determine if their waste is regulated as a listed

hazardous waste.

There are four different criteria EPA uses to

decide whether or not to list a waste as hazardous.

Note that these four criteria do not directly

correspond to the four different lists of hazardous

waste. The four criteria are:

• The waste typically contains harmful chemicals

(and other factors, such as risk and

bioaccumulation potential) which indicate that

it could pose a threat to human health and the

environment in the absence of special

regulation. Such wastes are known as toxic

listed wastes.

• The waste contains such dangerous chemicals

that it could pose a threat to human health

and the environment even when properly

managed. These wastes are fatal to humans

and animals even in low doses. Such wastes

are known as acute hazardous wastes.

• The waste typically exhibits one of the four

characteristics of hazardous waste: ignitability,

corrosivity, reactivity, and toxicity.

• EPA has cause to believe that, for some other

reason, the waste typically fits within the

statutory definition of hazardous waste

developed by Congress.

DEFINITION OF HAZARDOUS WASTE

In RCRA §1004(5), Congress defined hazardous

waste as a solid waste, or combination of solid

wastes, which because of its quantity, concentration,

or physical, chemical, or infectious characteristics

may:

(a) Cause, or significantly contribute to, an increase

in mortality or an increase in serious irreversible,

or incapacitating reversible, illness; or

(b) Pose a substantial present or potential hazard to

human health or the environment when

improperly treated, stored, transported, or

disposed of, or otherwise managed.

Based on this broad definition, Congress instructed

EPA to develop more specific criteria for defining

solid and hazardous waste. Congress believed that

EPA should define hazardous waste using two

different mechanisms: by listing certain specific solid

wastes as hazardous (i.e., wastes from certain

industrial processes or sources), and by identifying

characteristics (i.e., physical or chemical properties)

which, when exhibited by a solid waste, make it

hazardous. Taking Congress’ lead, EPA proceeded

to develop an elaborate definition of hazardous

waste that included both of these mechanisms.
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• The K list — The K list includes wastes from

specific industries. As a result, K list wastes are

known as wastes from specific sources. The K

list is found at 40 CFR §261.32.

• The P list and the U list — These two lists

include pure or commercial grade

formulations of specific unused chemicals.

Chemicals are included on the P list if they are

acutely toxic. A chemical is acutely toxic if it

is fatal to humans in low doses, if scientific

studies have shown that it has lethal effects on

experimental organisms, or if it causes serious

irreversible or incapacitating illness. The U list

is generally comprised of chemicals that are

toxic, but also includes chemicals that display

other characteristics, such as ignitability or

reactivity. Both the P list and U list are

codified at 40 CFR §261.33.

Each list includes anywhere from 30 to a few

hundred listed hazardous wastestreams. All of the

wastes on these lists are assigned an identification

number (i.e., a waste code) consisting of the letter

associated with the list (i.e., F, K, P, or U) followed

by three numbers. For example, wastes on the F

list may be assigned a waste code ranging from

F001 to F039, while wastes on the K list may be

assigned a waste code ranging from K001 to K161.

These waste codes are an important part of the

RCRA regulatory system since waste code

assignment has important implications for the

future management standards that will apply to

the waste.

The F List: Wastes From Nonspecific Sources

The F list designates hazardous wastes from

common industrial and manufacturing processes.

F list wastes usually consist of chemicals that have

been used for their intended purpose in an

industrial process. The F list wastes can be

divided into seven groups, depending on the type

of manufacturing or industrial operation that

creates them:

• Spent solvent wastes (waste codes F001

through F005)

• Electroplating and other metal finishing wastes

(F006 through F012 and F019)

• Dioxin-bearing wastes (F020 through F023

and F026 through F028)

• Chlorinated aliphatic hydrocarbons

production wastes (F024 and F025)

• Wood preserving wastes (F032, F034, and

F035)

• Petroleum refinery wastewater treatment

sludges (F037 and F038)

• Multisource leachate (F039).

Spent Solvent Wastes

The spent solvent waste listings (F001 through

F005) apply to wastestreams that are generated

from the use of certain common organic solvents.

HAZARD CODES

To indicate its reason for listing a waste, EPA assigns

a hazard code to each waste listed on the F, K, P,

and U lists. The last four hazard codes in the table

below apply to wastes that have been listed because

they typically exhibit one of the four regulatory

characteristics of hazardous waste. The first two

hazard codes apply to listed wastes whose

constituents pose additional threats to human health

and the environment. The hazard codes indicating

the basis for listing a waste are:

Toxic Waste (T)

Acute Hazardous Waste (H)

Ignitable Waste (I)

Corrosive Waste (C)

Reactive Waste (R)

Toxicity Characteristic Waste (E)

The hazard codes assigned to listed wastes affect

the regulations that apply to handling the waste. For

instance, acute hazardous wastes accompanied by

the hazard code (H) are subject to stricter

management standards than most other wastes.
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Solvents are commonly used in various industries,

such as mechanical repair, dry cleaning, and

electronics manufacturing, for degreasing and

cleaning in addition to other functions. While

solvents are chemicals with many uses, these

listings only apply to solvents that are used as

solvents for their solvent properties (e.g., to

solubilize, dissolve, or mobilize other constituents)

and are spent (e.g., cannot be used further

without reprocessing). In addition, these listings

only apply to solvents that contain one or more of

the specific organic solvent constituents found in

the F001-F005 narrative descriptions. Lastly, these

listings only cover solvents that were above a

certain concentration before use.

Electroplating and Other Metal Finishing

Wastes

The electroplating and other metal finishing

waste listings (F006 through F012 and F019) apply

to wastestreams that are commonly produced

during electroplating and other metal finishing

operations. Diverse industries use electroplating

and other methods to change the surface of metal

objects in order to enhance the appearance of the

objects, make them more resistant to corrosion, or

impart some other desirable property to them.

Industries involved in plating and metal finishing

range from jewelry manufacture to automobile

production.

Dioxin-Bearing Wastes

The dioxin-bearing waste listings (F020

through F023 and F026 through F028) describe a

number of wastestreams that EPA believes are

likely to contain dioxins, which are allegedly

among the most dangerous known chemical

compounds. The dioxin listings apply primarily to

manufacturing process wastes from the production

of specific pesticides or specific chemicals used in

the production of pesticides. With the exception

of F028, all of the dioxin-bearing wastes are

considered acutely hazardous wastes and are

designated with the hazard code (H). These

wastes are therefore subject to stricter

management standards than other hazardous

wastes.

Chlorinated Aliphatic Hydrocarbon

Production Wastes

The chlorinated aliphatic hydrocarbons

production wastes (F024 and F025) list certain

wastestreams produced by the manufacture of

chlorinated aliphatic hydrocarbons. Chlorinated

aliphatic hydrocarbons are used in the

manufacture of certain pesticides and fire

retardants.

Wood Preserving Wastes

The wood preserving waste listings (F032,

F034, and F035) apply to certain wastes from

wood preserving operations. Most wood used for

construction or other nonfuel applications is

chemically treated to slow the deterioration

caused by decay and insects. For example,

telephone poles, railroad cross ties, and other

wood products are treated to withstand the rigors

of outdoor use.

Wood preservation typically involves coating

lumber with pentachlorophenol, creosote, or

preservatives containing arsenic or chromium.

The wood preserving process creates wastestreams

containing these chemicals, such as excess

preservative solution that drips from wood

products after treatment. Waste from wood

preservation using pentachlorophenol is F032,

waste from use of creosote is F034, and waste

from treating wood with arsenic or chromium is

F035.

These listings (as well as some K list waste

listings) also apply to a variety of other residues

from wood preserving.
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Petroleum Refinery Wastewater Treatment

Sludges

The petroleum refinery wastewater treatment

sludge listings (F037 and F038) apply to specific

wastestreams from petroleum refineries. The

petroleum refining process

typically creates large

quantities of

contaminated wastewater.

Before this wastewater

can be discharged to a

river or sewer, it must be

treated to remove oil,

solid material, and

chemical pollutants.

To remove most of this oily waste from the

wastewater, refineries typically use two methods.

In the first step, gravity separates the pollutants

from the wastewater. The solids and heavier

pollutants sink to the bottom of a tank, forming a

sludge, while the lighter materials (called float)

float to the surface of the wastewater, where they

can be skimmed off. This sludge is F037. The

second step uses physical (stirring or agitating) and

chemical means to separate remaining pollutants

from the wastewater into sludge and float. This

sludge and float are F038.

Multisource Leachate

The F039 listing applies to multisource

leachate, the liquid material that accumulates at

the bottom of a hazardous waste landfill. The

leachate that percolates through landfills,

particularly hazardous waste landfills, usually

contains high concentrations of chemicals, and is

often collected to minimize the potential for it to

enter and contaminate the soil or ground water

below the unit.

The K List: Wastes From Specific Sources

The K list designates hazardous wastes from

specific sectors of industry and manufacturing.

Like F list wastes, K list wastes are manufacturing

process wastes, and usually consist of chemicals

that have been used for their intended purpose.

To determine whether a waste qualifies as Klisted, a facility must first determine whether the

waste fits within one of the 17 different industrial

or manufacturing categories on the list. Second, a

facility must determine if this waste matches one

of the detailed K list waste descriptions in 40 CFR

§261.32. The 17 industries that generate K list

wastes are:

• Wood preservation

• Organic chemicals manufacturing

• Pesticides manufacturing

• Petroleum refining

• Primary copper production

• Primary zinc production

• Ferroalloys production

• Veterinary pharmaceuticals manufacturing

• Inorganic pigment manufacturing

• Inorganic chemicals manufacturing

• Explosives manufacturing

• Iron and steel production

• Primary lead production

• Primary aluminum production

• Secondary lead processing

• Ink formulation

• Coking (processing of coal to produce coke, a

material used in iron and steel production).
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The P and U Lists: Discarded Commercial

Chemical Products

The P and U lists designate as hazardous waste

pure and commercial grade formulations of

certain unused chemicals that are being disposed.

Unused chemicals may become wastes for a

number of reasons. For example, some unused

chemicals are spilled by accident. Others are

intentionally discarded because they are offspecification and cannot serve the purpose for

which they were originally produced. For a waste

to qualify as P- or U-listed, the waste must meet

the following three criteria:

• The waste must contain one of the chemicals

listed on the P or U list

• The chemical in the waste must be unused

• The chemical in the waste must be in the form

of a CCP.

For purposes of the P and U lists, a CCP is

defined as a chemical that is one of the following:

• 100 percent pure

• Technical (e.g., commercial) grade

• The sole active ingredient in a chemical

formulation.

While 100 percent pure means that the

chemical is the only chemical constituent in the

product, technical grade means that the

formulation is not 100 percent pure, but is of a

grade of purity that is either marketed or

recognized in general usage by the chemical

industry. Sole active ingredient means that the

chemical is the only ingredient serving the

function of the formulation. For instance, a

pesticide made for killing insects may contain a

poison such as heptachlor, as well as various

solvent ingredients which act as carriers or lend

other desirable properties to the poison. Although

all of these chemicals may be capable of killing

insects, only the heptachlor serves the primary

purpose of the insecticide product. The other

chemicals involved are present for other reasons,

not because they are poisonous. Therefore,

heptachlor is the sole active ingredient in such a

formulation even though it may be present in low

concentrations.

■ Delistings

The RCRA regulations provide a form of relief

for listed wastes with low concentrations of

hazardous constituents. Through a site-specific

process known as delisting, a waste handler can

submit to an EPA Region or state a petition

demonstrating that even though a particular

wastestream generated at its facility is a listed

hazardous waste, it does not pose sufficient

hazard to merit RCRA regulation. For example, a

waste generated at a specific facility may meet a

listing description even though the process uses

different raw materials than EPA assumed were

used when listing the waste, thus the waste may

not contain the contaminants for which it was

listed. Similarly, after treatment of a listed waste,

the residue may no longer pose a threat to human

health and the environment.

Specifically, the petition must demonstrate that

the waste does not:

• Meet the criteria for which it was listed

• Exhibit any hazardous waste characteristics (as

discussed later in this chapter)

• Pose a threat to human health and the

environment by being hazardous for any other

reason (e.g., does not contain additional

constituents that could pose a threat).
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If the EPA Region or state grants a delisting

petition, the particular wastestream at that facility

will not be regulated as a listed hazardous waste.

IS THE WASTE A CHARACTERISTIC

HAZARDOUS WASTE?

After a facility determines its waste is a solid

waste and is not excluded from the definitions of

solid or hazardous waste, it must determine if the

waste is a hazardous waste. This entails

determining if the waste is listed, and also if the

waste is characteristic. Even if a waste is a listed

hazardous waste, the facility must then still

determine if the waste exhibits a characteristic.

Characteristic wastes are wastes that exhibit

measurable properties which indicate that a waste

poses enough of a threat to deserve regulation as

hazardous waste. EPA tried to identify

characteristics which, when present in a waste,

can cause death or illness in humans or lead to

ecological damage. The characteristics are an

essential supplement to the hazardous waste

listings. For example, some wastes may not meet

any listing description because they do not

originate from specific industrial or process

sources, but the waste may still pose threats to

human health and the environment. As a result, a

facility is also required to determine whether such

a waste possesses a hazardous property (i.e.,

exhibits a hazardous waste characteristic). The

characteristics are applied to any waste from any

industry.

Even if a waste does meet a hazardous waste

listing description, the facility must still determine

if the waste exhibits a characteristic. If such listed

wastes do exhibit a characteristic, the waste poses

an additional hazard to human health and the

environment, and may necessitate additional

regulatory precautions. For example, wastes that

are both listed and characteristic may have more

extensive LDR requirements, than those that are

only listed (the LDR program is fully discussed in

Section III, Chapter 6).

EPA decided that the characteristics of

hazardous waste should be detectable by using a

standardized test method or by applying general

knowledge of the waste’s properties. Given these

criteria, EPA established four hazardous waste

characteristics:

• Ignitability

• Corrosivity

• Reactivity

• Toxicity.

■ Ignitability

The ignitability characteristic identifies

wastes that can readily catch fire and sustain

combustion. Many paints, cleaners, and other

industrial wastes pose such a hazard. Liquid and

nonliquid wastes are treated differently by the

ignitability characteristic.

DETERMINING BOTH LISTINGS AND

CHARACTERISTICS

A facility must determine both listings and

characteristics. Even if a waste is a listed

hazardous waste, the facility must then still

determine if the waste exhibits a characteristic

because waste generators are required to fully

characterize their listings. While some wastes

may not meet any listing description because

they do not originate from specific industrial or

process sources, the waste may still pose

threats to human health and the environment.

As a result, a facility is also required to

determine whether such a waste possesses a

hazardous property (i.e., exhibits a hazardous

waste characteristic).
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Most ignitable

wastes are liquid in

physical form. EPA

selected a flash

point test as the

method for

determining

whether a liquid

waste is

combustible enough to deserve

regulation as hazardous. The flash point test

determines the lowest temperature at which the

fumes above a waste will ignite when exposed to

flame.

Many wastes in solid or nonliquid physical

form (e.g., wood, paper) can also readily catch fire

and sustain combustion, but EPA did not intend to

regulate most of these nonliquid materials as

ignitable wastes. A nonliquid waste is considered

ignitable if it can spontaneously catch fire or catch

fire through friction or absorption of moisture

under normal handling conditions and can burn

so vigorously that it creates a hazard. Certain

compressed gases are also classified as ignitable.

Finally, substances meeting the Department of

Transportation’s definition of oxidizer are classified

as ignitable wastes. Ignitable wastes carry the

waste code D001 and are among the most

common hazardous wastes. The regulations

describing the characteristic of ignitability are

codified at 40 CFR §261.21.

■ Corrosivity

The corrosivity

characteristic

identifies wastes

that are acidic or

alkaline (basic).

Such wastes can

readily corrode or

dissolve flesh,

metal, or other

materials. They are also among the most common

hazardous wastes. An example is waste sulfuric

acid from automotive batteries. EPA uses two

criteria to identify liquid and aqueous corrosive

hazardous wastes. The first is a pH test. Aqueous

wastes with a pH greater than or equal to 12.5 or

less than or equal to 2 are corrosive. A liquid

waste may also be corrosive if it has the ability to

corrode steel under specific conditions. Physically

solid, nonaqueous wastes are not evaluated for

corrosivity. Corrosive wastes carry the waste code

D002. The regulations describing the corrosivity

characteristic are found at 40 CFR §261.22.

■ Reactivity

The reactivity

characteristic

identifies wastes

that readily

explode or

undergo violent

reactions.

Common

examples are

discarded

munitions or explosives. In many cases, there is

no reliable test method to evaluate a waste’s

potential to explode or react violently under

common handling conditions. Therefore, EPA

uses narrative criteria to define most reactive

wastes and requires waste handlers to use their

best judgment in determining if a waste is

sufficiently reactive to be regulated. This is

possible because reactive hazardous wastes are

relatively uncommon and the dangers that they

pose are believed to be well known to the few

waste handlers who deal with them.

A waste is reactive if it meets any of the

following criteria:

• It can explode or violently react when

exposed to water or under normal handling

conditions

The ignitability characteristic

identifies wastes that can

readily catch fire and sustain

combustion.

The corrosivity characteristic

identifies wastes that are

acidic or alkaline (basic) and

can readily corrode or

dissolve flesh, metal, or

other materials.

The reactivity characteristic

identifies wastes that readily

explode or undergo violent

reactions.
III-26

 SECTION III SECTION III Managing Hazardous Waste—RCRA Subtitle C

Chapter 1: Hazardous Waste Identification

• It can create toxic fumes or gases when

exposed to water or under normal handling

conditions

• It meets the criteria for classification as an

explosive under DOT rules

• It generates toxic levels of sulfide or cyanide

gas when exposed to a pH range of 2 through

12.5.

Wastes exhibiting the characteristic of

reactivity are assigned the waste code D003. The

reactivity characteristic is described in the

regulations at 40 CFR §261.23.

■ Toxicity

When hazardous waste is disposed of in a

land disposal unit, toxic compounds or elements

can leach into underground drinking water

supplies and expose users of the water to

hazardous chemicals and constituents. EPA

developed the toxicity characteristic (TC) to

identify wastes likely to leach dangerous

concentrations of toxic chemicals into ground

water.

In order to predict whether any particular

waste is likely to leach chemicals into ground

water at dangerous levels, EPA designed a lab

procedure to replicate the leaching process and

other conditions that occur when wastes are

buried in a typical municipal landfill. This lab

procedure is known as the Toxicity Characteristic

Leaching Procedure (TCLP).

The regulations require a facility to apply the

TCLP to its hazardous waste samples in order to

create a liquid leachate. This leachate would be

similar to the leachate generated by a landfill

containing a mixture of household and industrial

wastes. Once this leachate is created via the

TCLP, the waste handler must determine whether

it contains any of 40 different toxic chemicals in

amounts above the specified regulatory levels (see

Figure III-7). These regulatory levels are based on

ground water modeling studies and toxicity data

that calculate the limit above which these

common toxic compounds and elements will

threaten human health and the environment. If

the leachate sample contains a concentration

above the regulatory limit for one of the specified

chemicals, the waste exhibits the toxicity

characteristic and carries the waste code

associated with that compound or element. The

regulations describing the toxicity characteristic

D004

D005

D018

D006

D019

D020

D021

D022

D007

D023

D024

D025

D026

D016

D027

D028

D029

D030

D012

D031

D032

D033

D034

D008

D013

D009

D014

D035

D036

D037

D038

D010

D011

D039

D015

D040

D041

D042

D017

D043

5.0

100.0

0.5

1.0

0.5

0.03

100.0

6.0

5.0

200.0

200.0

200.0

200.0

10.0

7.5

0.5

0.7

0.13

0.02

0.008

0.1

0.5

3.0

5.0

0.4

0.2

10.0

200.0

2.0

100.0

5.0

1.0

5.0

0.7

0.5

0.5

400.0

2.0

1.0

0.2

 Arsenic 

 Barium

 Benzene

 Cadmium

 Carbon tetrachloride

 Chlordane

 Chlorobenzene

 Chloroform

 Chromium

 o-Cresol*

 m-Cresol*

 p-Cresol*

 Total Cresols*

 2,4-D

 1,4-Dichlorobenzene

 1,2-Dichloroethane

 1,1-Dichloroethylene

 2,4-Dinitrotoluene

 Endrin

 Heptachlor (and its epoxide)

 Hexachlorobenzene

 Hexachlorobutadiene

 Hexachloroethane

 Lead

 Lindane

 Mercury

 Methoxychlor

 Methyl ethyl ketone

 Nitrobenzene

 Pentachlorophenol

 Pyridine

 Selenium

 Silver

 Tetrachloroethylene

 Toxaphene

 Trichloroethylene

 2,4,5-Trichlorophenol

 2,4,6-Trichlorophenol

 2,4,5-TP (Silvex)

 Vinyl chloride

*if o-, m-, and p-cresols cannot be individually measured,

 the regulatory level for total cresols is used.

Waste Code Contaminant Concentration

Figure III-7: TCLP REGULATORY LEVELS
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Managing Hazardous Waste—RCRA Subtitle C SECTION III SECTION III

Chapter 1: Hazardous Waste Identification

are codified at 40 CFR §261.24, and the TC

regulatory levels appear in Table 2 of that same

section.

SPECIAL REGULATORY

CONVENTIONS

Once a facility generates a hazardous waste,

the waste may become mixed with other wastes,

be treated and produce residues, or even be

spilled. RCRA provides special regulatory

provisions to address the regulatory status of

hazardous wastes in these situations.

■ Mixture Rule

The mixture rule is intended to ensure that

mixtures of listed wastes with nonhazardous solid

wastes are regulated in a manner that minimizes

threats to human health and the environment.

Listed Wastes

The mixture rule regulates a combination of

any amount of a nonhazardous solid waste and

any amount of a listed hazardous waste as a listed

hazardous waste (see Figure III-8). Even if a small

vial of listed waste is mixed with a large quantity

of nonhazardous waste, the resulting mixture

bears the same waste code and regulatory status

as the original listed component of the mixture,

unless the generator obtains a delisting. This is

intended to prevent a facility from

mixing a listed waste with a

nonhazardous waste in order to

escape having to manage the

waste as hazardous.

Exemptions

There are several exemptions

from the mixture rule. One

exemption from the mixture rule

applies to mixtures of solid wastes and wastes

listed solely because they exhibit a characteristic

(see Figure III-8). When EPA lists a waste as

hazardous, the Agency assigns a hazard code to

the waste as a reason for the listing. If a

hazardous waste is listed for ignitability (hazard

code I), corrosivity (hazard code C), or reactivity

(hazard code R), and that waste is mixed with a

solid waste, then the original listing does not carry

through to the resulting mixture as long as that

mixture does not exhibit any hazardous waste

characteristics. The reason behind this exemption

is that the such wastes were originally listed for the

risks posed by certain characteristics, and if a

waste mixture does not exhibit those

characteristics (e.g., it does not pose a significant

risk), then the mixture does not warrant Subtitle C

regulation. For example, EPA listed the F003

spent solvents as hazardous because these wastes

typically display the ignitability characteristic. If

F003 waste is inadvertently mixing with another

waste, and the resulting mixture does not exhibit

any characteristic, the F003 listing no longer

applies.

Another exemption from the mixture rule

applies to certain listed hazardous wastes that are

discharged to wastewater treatment facilities in

very small or de minimis amounts. Many

industrial facilities produce large quantities of

nonhazardous wastewaters as their primary

wastestreams. These wastewaters are typically

discharged to a water body or local sewer system

after being treated to remove pollutants, as

Any amount of 

nonhazardous solid 

waste

+ =

LISTED 

HAZARDOUS 

WASTE

+ =

NONHAZARDOUS 

WASTE IF MIXTURE 

DOES NOT EXHIBIT 

ANY 

CHARACTERISTIC

Any amount of 

nonhazardous solid 

waste

Any amount of listed 

hazardous waste

Any amount of listed 

hazardous waste 

that is listed solely 

for exhibiting a 

characteristic

Figure III-8: THE MIXTURE RULE
III-28

 SECTION III SECTION III Managing Hazardous Waste—RCRA Subtitle C

Chapter 1: Hazardous Waste Identification

required by CWA. At many of these large

facilities, on-site cleaning, chemical spills, or

laboratory operations create relatively small

amounts of hazardous waste. For example, a

textile plant producing large quantities of

nonhazardous wastewater can generate a

secondary wastestream of listed spent solvents

from cleaning equipment. Routing such

secondary hazardous wastestreams to the facility’s

wastewater treatment system is a practical way of

treating and disposing of these wastes. This

management option triggers the mixture rule,

since even a very small amount of a listed

wastestream combined with very large volumes of

nonhazardous wastewater causes the entire

mixture to be listed. EPA provided an exemption

from the mixture rule for situations where

relatively small quantities of listed hazardous

wastes are routed to large-volume wastewater

treatment systems.

Other exemptions apply to mixtures of listed

and characteristic wastes with mining and mineral

processing that are exempt from the definition of

hazardous waste under the Bevill exemption.

Wastes that are hazardous via the mixture rule can

also exit Subtitle C regulation through the delisting

process.

■ Derived-From Rule

Hazardous waste treatment, storage, and

disposal processes often generate residues that

may contain high concentrations of hazardous

constituents. In order to adequately protect

human health and the environment from the

threats posed by these potentially harmful wastes,

the derived-from rule governs the regulatory

status of such listed waste residues.

Listed Wastes

Residues produced from the treatment of

listed hazardous wastes may pose a significant

threat to human health and the environment. If

not captured by the waste’s listing description,

such waste could escape regulation. To close this

potential regulatory gap, EPA created the derivedfrom rule which states that any material derived

from a listed hazardous waste is also a listed

hazardous waste (see Figure III-9). For example,

ash created by burning a hazardous waste is

considered derived-from that hazardous waste.

Thus, such ash bears the same waste code and

regulatory status as the original listed waste,

regardless of the ash’s actual properties. This

principle applies regardless of the actual health

threat posed by the waste residue or the residue’s

chemical composition.

Exemptions

There are several regulatory exemptions from

the derived-from rule. The first exemption applies

to products reclaimed from hazardous wastes.

Many listed hazardous wastes can be recycled to

make new products or processed to recover

usable materials with economic value. Such

Any residue from the treatment, storage, 

or disposal of a listed waste...

...is still a listed hazardous waste...

...unless waste is recycled to make new products 

or processed to recover useable materials with 

economic value (provided that product is not 

used in a manner constituting disposal or burned 

for energy recovery)

Listed hazardous waste

Figure III-9: THE DERIVED-FROM RULE
III-29

Managing Hazardous Waste—RCRA Subtitle C SECTION III SECTION III

Chapter 1: Hazardous Waste Identification

products derived-from recycled hazardous wastes

are no longer solid wastes, provided that they are

not used in a manner constituting disposal or

burned for energy recovery (see Figure III-9). The

other exemptions from the derived-from rule

apply to residues from specific treatment

operations. Wastes that are hazardous via the

derived-from rule can also exit Subtitle C

regulation through the delisting process.

■ Contained-In Policy

Sometimes listed and characteristic wastes are

spilled onto soil or contaminate equipment,

buildings, or other structures. The mixture and

derived-from rules do not apply to such

contaminated soil and materials because these

materials are not actually wastes. Soil is

considered environmental media (e.g., soil,

ground water, sediment), while the equipment,

buildings, and structures are considered debris

(e.g., a broad category of larger manufactured and

naturally occurring objects that are commonly

discarded). Examples of debris include:

• Dismantled construction materials, such as

used bricks, wood beams, and chunks of

concrete

• Decommissioned industrial equipment, such

as pipes, pumps, and dismantled tanks

• Other discarded manufactured objects, such

as personal protective equipment (e.g., gloves,

coveralls, eyewear)

• Large, naturally occurring objects, such as tree

trunks and boulders.

Environmental media and debris are

contaminated with hazardous waste in a number

of ways. Environmental media become

contaminated through accidental spills of

hazardous waste or spills of product chemicals

which, when spilled, become hazardous wastes.

Debris can also be contaminated through spills.

Most debris in the form of industrial equipment

and personal protective gear becomes

contaminated with waste or product chemicals

during normal industrial operations.

In order to address such contaminated media

and debris, EPA created the contained-in policy

to determine when contaminated media and

debris must be managed as RCRA hazardous

wastes.

Environmental media are not, in and of

themselves, waste, but are regulated as hazardous

waste when they contain (are contaminated by) a

RCRA listed hazardous waste or exhibit a

characteristic. In these cases, the media and

debris must be managed as if they were hazardous

waste. EPA or states can determine that media

and debris no longer contain hazardous waste by

determining that the media or debris no longer

poses a sufficient health threat to deserve RCRA

regulation. Once this contained-out

determination is made, the media and debris are

generally no longer regulated under RCRA Subtitle

C. However, under certain circumstances, the

RCRA LDR requirements might continue to apply.

HAZARDOUS WASTE

IDENTIFICATION RULES

RCRA regulates hazardous wastes either

because they carry a listing code, or because they

exhibit a characteristic. Characteristics are based

on actual risks that the materials may pose.

Listings codes however, can remain with a waste

even if it has very low concentrations of harmful

materials, or is considerably different from the

waste for which the listing was originally created.

RCRA listing codes often apply to hazardous waste

mixtures; treatment, storage, and disposal

residues; and contaminated media and debris
III-30

 SECTION III SECTION III Managing Hazardous Waste—RCRA Subtitle C

Chapter 1: Hazardous Waste Identification

based on the source of the waste rather than the

risks that such materials pose to human health and

the environment.

In these situations, it is entirely possible that

the mixtures, residues, or media and debris

contain low concentrations of hazardous

constituents, posing minimal threats to human

health and the environment, but are still regulated

as hazardous. Similarly, listed wastes may also

contain low concentrations of hazardous

constituents, but will still be regulated as

hazardous because they originate from a specific

industrial source or process. In order to add

flexibility to the hazardous waste identification

system, EPA proposed two hazardous waste

identification rules to establish and provide a

regulatory mechanism through which low-risk

wastes can exit Subtitle C regulation.

The proposed Hazardous Waste

Identification Rule for Waste (HWIR-waste)

proposes exit levels for each of the hazardous

constituents in listed wastes. If a facility can

determine that the concentrations of hazardous

constituents in the waste are below the exit levels,

then the waste will no longer carry a listing, and

will no longer be hazardous (provided it does not

exhibit a characteristic). In essence, listed wastes

with low concentrations of hazardous constituents,

hazardous waste mixtures, and hazardous residues

that do not pose significant risks will be able to

exit Subtitle C regulation as long as they do not

pose a threat to human health or the

environment. EPA plans to write a new HWIRwaste proposal by October 31, 1999, and finalize

the HWIR-waste rule by April 30, 2001.

The Hazardous Waste Identification Rule for

Contaminated Media (HWIR-media) was

proposed in April 1996, and requested public

comment on several ways to improve regulations

on the management of remediation wastes, such

as contaminated media, debris, and old sludges

from hazardous waste cleanups. EPA had hoped

to make comprehensive changes to the regulation

of these remediation wastes, but public comments

were extremely divided on the course of proper

reform. Therefore, the Agency is planning to

finalize, in June 1998, a few of the elements of the

April 1996 proposal, but not to promulgate a

comprehensive reform. EPA plans to finalize

provisions for streamlined permits for managing

remediation wastes, increased flexibility for staging

wastes prior to off-site management, an exclusion

for certain dredged material, and streamlined

RCRA state authorization procedures. As part of a

separate rulemaking, LDR Phase IV, EPA finalized

new LDR treatment standards for hazardous soils.

(LDR is fully discussed in Section III, Chapter 6.)

MIXED WASTE

RCRA specifically exempts certain radioactive

mixed materials from the definition of solid waste.

However, some radioactive material may be

mixed with hazardous wastes that are regulated

under RCRA. In addition, a facility may generate

a hazardous waste that is also radioactive.

Because the material in both of these situations

contains both radioactive material and RCRA

hazardous waste, it is referred to as mixed waste

under RCRA. RCRA and AEA regulate these

mixed wastes jointly. AEA regulates the RCRAexempt radioactive portion and RCRA regulates

the hazardous waste portion. Mixed waste

generators include

DOE, power plants,

labs, hospitals, and

universities using

radioactive

materials.
III-31

Managing Hazardous Waste—RCRA Subtitle C SECTION III SECTION III

Chapter 1: Hazardous Waste Identification

SUMMARY

In order to determine if a facility is subject to

RCRA Subtitle C, the owner and operator must

determine if they have a hazardous waste. This

determination must be made by using the

following methodology:

• Is the material a solid waste?

• Is the waste excluded?

• Is the waste a listed hazardous waste?

• Is the waste a characteristic waste?

A waste must first be a solid waste before it

can be a hazardous waste. A solid waste is a

waste that is abandoned, inherently waste-like, a

certain military munition, or recycled. On the

other hand, if a solid waste is directly recycled

without prior reclamation by being either used as

an ingredient, used as a product substitute, or

returned to the production process, then the

material is not regulated as a waste at all. If such

recycled materials, however, are used in a manner

constituting disposal; burned for energy recovery,

used to produce a fuel, or contained in fuels;

accumulated speculatively; or dioxin-containing

wastes considered inherently waste like; then they

are regulated as solid wastes. If a recycled

material needs reclamation prior to direct use or

reuse, its regulatory status is determined by the

type of material that it is:

• Spent materials are regulated as solid wastes

when reclaimed; used in a manner

constituting disposal; burned for energy

recovery, used to produce a fuel, or contained

in fuels; or accumulated speculatively.

• Listed sludges are solid wastes when

reclaimed; used in a manner constituting

disposal; burned for energy recovery, used to

produce a fuel, or contained in fuels; or

accumulated speculatively.

• Characteristic sludges are not solid wastes

when reclaimed, unless they are used in a

manner constituting disposal; burned for

energy recovery, used to produce a fuel, or

contained in fuels; or accumulated

speculatively.

• Listed by-products are solid wastes when

reclaimed; used in a manner constituting

disposal; burned for energy recovery, used to

produce a fuel, or contained in fuels; or

accumulated speculatively.

• Characteristic by-products are not solid wastes

when reclaimed, unless they are used in a

manner constituting disposal; burned for

energy recovery, used to produce a fuel, or

contained in fuels; or accumulated

speculatively.

• CCPs are not solid wastes when reclaimed,

unless they are used in a manner constituting

disposal; or burned for energy recovery, used

to produce a fuel, or contained in fuels.

• Scrap metal is a solid waste when reclaimed;

used in a manner constituting disposal;

burned for energy recovery, used to produce a

fuel, or contained in fuels; or accumulated

speculatively.

Regardless of the type of recycling that takes

place, it must be legitimate and not sham

recycling.

If the waste is a solid waste, it may be

excluded from the Subtitle C hazardous waste

regulations. There are four categories of

exclusions:

• Exclusions from the definition of solid waste

• Exemptions from the definition of hazardous

waste

• Exclusions for waste generated in raw material,

product storage, or manufacturing units
III-32

 SECTION III SECTION III Managing Hazardous Waste—RCRA Subtitle C

Chapter 1: Hazardous Waste Identification

• Exclusions for laboratory samples and waste

treatability studies.

If the waste fits one of these categories, it is

not regulated as a RCRA hazardous waste, and the

hazardous waste requirements do not apply.

If the waste is a solid waste and is not

excluded, a facility must determine if it is a listed

hazardous waste. The F, K, P, and U lists provide

narrative descriptions of wastes from specific

industrial processes and sources. Wastes meeting

any of these descriptions are listed hazardous

wastes. However, through the delisting process,

facilities can demonstrate that their wastes does

not pose sufficient hazard to warrant Subtitle C

regulation as a listed hazardous waste.

Wastes may also be hazardous if they exhibit a

characteristic. Even if a facility’s waste is listed,

the owner and operator must still determine if it

exhibits a characteristic. The four characteristics

are:

• Ignitability

• Corrosivity

• Reactivity

• Toxicity.

There are special regulatory conventions or

provisions that apply to hazardous waste mixtures;

treatment, storage, and disposal residues; and

contaminated media and debris. These provisions

are known as the mixture rule, the derived-from

rule, and the contained-in policy.

In the future, low-risk wastes with low

concentrations of hazardous constituents will be

able to exit Subtitle C regulation through riskbased exit levels established by HWIR-waste.

Through HWIR-media, EPA will also facilitate the

management of remediation wastes, such as

contaminated media, debris, and old sludges from

hazardous waste cleanups.

RCRA and AEA jointly regulate mixed waste,

or waste that is radioactive, and listed or

characteristic.