Hazardous Waste Identification

Two EPA lists identify specific chemicals as hazardous wastes.  These lists apply to unused quantities of certain pure and commercial-grade chemicals.  Chemicals which have reached their expiration date, but which have not been used in a process, may be listed wastes.  Products which contain a listed material as the sole active ingredient may also be listed wastes.

• “P” Wastes:  Also known as “acutely hazardous wastes”.  The P-list includes 239 specific compounds such as carbon disulfide, Aldrin, and hydrogen cyanide.  Click here for a table of all P-listed wastes
• “U” Wastes:  The U-list includes 472 additional compounds, such as acetone, methanol, and mercury. Click here for a table of all U-listed wastes.

Please note that if your waste is P-listed, a maximum of one quart of that waste may be accumulated in a Satellite Accumulation Area.

EPA also includes two lists of wastes generated from various processes:

• “F” Wastes: 28 non-specific waste sources from common processes, such as spent solvents.  Click here for all F-listed sources.
• “K” Wastes: 111 wastes associated with specific manufacturing processes, such as wastewater treatment sludge.  These are rarely found at WSU.  Click here for all K-listed sources.

Any wastes generated at WSU which appear on any of the above lists must be managed and disposed of as hazardous waste.  Contact EHS for assistance.

Wastes which are not listed may still be regulated, based on their characteristics.

In addition to the listed wastes discussed on the previous tab, EPA has defined a set of four characteristics which require materials to be managed as hazardous wastes.  The four characteristics are:

• Ignitability
• Corrosivity
• Reactivy
• Toxicity

Ignitability Characteristic

Ignitable wastes may include solids, liquids, or gases, if they meet the following:

• Any liquid solution with a flashpoint of less than 60 degrees C (140 degrees F), as determined by Pensky-Martens closed-cup flash tester
• Any non-liquid which is capable, under standard temperature and pressure, of causing fire through friction, absorption of moisture or spontaneous chemical changes and, when ignited, burns so vigorously and persistently that it creates a hazard
• Any compressed gas which:
  • forms a flammable mixture in air at a concentration of 13 percent or less (by volume), or
  • which has a flammable range in air wider than 12 percent regardless of the lower limit, or
  • when igniting the gas at the valve, the flame projects more than 18 inches beyond the ignition source with the valve opened fully, or, the flame flashes back and burns at the valve with any degree of valve opening (tested using a specified method), or
  • has any significant propagation of flame away from the ignition source (tested using a specified method), or
  • has any explosion of the vapor-air mixture in a drum (tested using a specified method).
• Any oxidizer
  •  Oxidizers include any  ” substance such as a chlorate, permanganate, inorganic peroxide, or a nitrate, that yields oxygen readily to stimulate the combustion of organic matter.” , or which is “an organic compound containing the bivalent-O-O- structure and which may be considered a derivative of hydrogen peroxide where one or more of the hydrogen atoms have been replaced by organic radicals”, unless the material is classified as an explosive, forbidden for transportation, or it is determined that the predominant hazard of the material containing the organic peroxide is other than that of an organic peroxide.

Ignitable wastes are assigned the waste code D001

Corrosivity Characteristic

Corrosive wastes include:

• Any liquid with pH of 2 or less, or pH 12.5 or greater
• Any liquid which corrodes steel (SAE 1020) at a rate greater than 0.250 inches per year at 55 degrees C
• Any solid or semi-solid which, when testing according to Method 9045D, results in a pH of 2 or less or pH of 12.5 or greater.

Corrosive wastes are assigned the waste code D002.  Note: In Washington state, a solid which designates as waste only based on testing by Method 9045D will be assigned the waste code WSC2.

Reactivity Characteristic

Reactive wastes include any material which:

• is normally unstable and readily undergoes violent change without detonating;
• reacts violently with water;
• forms potentially explosive mixtures with water;
• when mixed with water, generates toxic gases, vapors or fumes in a quantity sufficient to present a danger to human health or the environment;
• is a cyanide or sulfide bearing waste which, when exposed to pH conditions between 2 and 12.5 can generate toxic gases, vapors or fumes in a quantity sufficient to present a danger to human health or the environment;
• is capable of detonation or explosive reaction if it is subjected to a strong initiating source or if heated under confinement;
• is readily capable of detonation or explosive decomposition or reaction at standard temperature and pressure; or
• is a forbidden explosive as defined in 49 C.F.R. 173.54, or a Class 1 explosive, Division 1.1, Division 1.2, Division 1.3, and Division 1.5, as defined in 49 C.F.R. 173.50 and 173.53

Reactive wastes are assigned the waste code D003.

Toxicity Characteristic

EPA has specified 40 individual compounds that form the basis for the toxicity characteristic.  If one or more of these compounds is present in the waste, and its leachable concentration (based on the Toxicity Characteristic Leaching Procedure) exceeds a specified level, the waste will be designated as toxic and assigned a waste code between D004 and D043.

The toxicity characteristic list, and corresponding concentration limits, can be viewed here.


In addition to the federal listed and characteristic wastes, Washington State has created additional categories which are more restrictive than those established by EPA.  These are known as “Criteria wastes”, or as “State only wastes”.  The management requirements for them are identical to the federally listed and characteristic wastes.

Washington State has established two categories of Criteria wastes:  Toxicity Criteria wastes and Persistence Criteria wastes.

Toxicity Criteria

Toxicity criteria wastes are identified based on data developed from bioassay testing on various fish and animals. These are represented as either LC50 or LD50.

To determine whether a waste meets the toxicity criteria, the toxicity of the substance must be compared to the values in the table below.  Toxicity values are often found in Section 11 of a material’s Safety Data Sheet (SDS). If multiple toxicity values are available for a substance, the most restrictive one should be used.

Toxic Category Table

Wastes which designate as toxic category D are assigned the waste code WT02. Those in toxic categories X, A, B, and C are assigned waste code WT01.

For mixtures of multiple chemicals, the toxic category (X, A, B, C, or D) must be identified for each component of the mixture. The total percentage in each toxic category must then be entered in the following formula:

Equivalent Concentration (EC) = (sum X%)+(sum A%/10)+(sum B%/100)+(sum C%/1000)+(sum D%/10000)

For example, for a waste containing 2% phenol (category C), 5% methanol (category D), 2% chloroform (category D) and 91% water, the EC would be:

EC = 0 + 0/10 + 0/100 + 2/1000 + 7/10000
EC = 0 + 0 + 0 + 0.002 + 0.0007 = 0.0027

Equivalent Concentration – 0.0027

The waste may then be designated based on its equivalent concentration, using the following table:

From the example above, the waste equivalent concentration was 0.0027, so it is a Toxic Criteria waste, and will be assigned waste code WT02.

Persistence Criteria

Wastes are designated as persistent criteria wastes based solely on the presence of Halogenated Organic Compounds (HOC) and/or Polycyclic Aromatic Hydrocarbons (PAH), as shown in the following table:

Polychlorinated biphenyls (PCBs) were widely used in thermal and electrical insulators prior to the late 1970s.  Products containing PCBs are now regulated at both the state and federal levels, but Washington State is far more restrictive than the federal EPA.

Washington State regulates PCBs at concentrations of 2 parts per million or greater. These wastes are assigned waste code WPCB.

WSU Tri-Cities discharges to the municipal sewer system under an Industrial Wastewater Discharge Permit issued by the City of Richland.  The requirements of that permit further restrict what materials may be discharged.  Many materials that may not designate as hazardous waste are still prohibited from sewer discharge. Therefore, only soap and water should be allowed down the drain.

EHS has established a Sink Discharge Permit program to provide review and approval for sewer discharge in compliance with the conditions of WSU Tri-Cities Wastewater Discharge Permit.  Contact EHS at 372-7163 for more information.