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Step 5: Check Washington State-only Criteria

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Washington State rules are more protective than federal hazardous waste rules. This means in addition to the rules we adopted from the federal Resource Conservation and Recovery Act (RCRA), Washington adds our own requirements. Wastes may designate as “dangerous” due to toxicity or persistence. These “state-only” waste codes start with the letter W—WT for toxic or WP for persistence (for example, WP01).

Washington Toxic Criteria
In addition to the federal toxic characteristic (D List), Washington toxic criteria wastes are regulated because testing shows they are lethal to fish or animals. Highly toxic chemicals will cause mortality at low concentrations.

Washington toxic criteria wastes are coded WT01 or WT02, depending on the concentration of its toxic constituents. WT01 wastes have a 2.2 quantity exclusion limit (QEL) – learn more about QEL and generator status. Details about WT01 and WT02 wastes are in the regulations (WAC 173-303-100).

You can test for this using a bioassay, which means a laboratory will use a sample of your waste to determine if it kills fish or other animals at a certain concentration.

Alternatively, you may be able to use a toxicity database to determine if it’s a Washington State toxic. These databases show the results from previous tests for specific chemicals on animals. You’ll need to know the concentration of specific chemicals in your waste. If you use information from such databases, you must use the most conservative results. If data are available for more than one test endpoint (that is, fish, oral rat, inhalation rat, or dermal rabbit), the value with the highest toxicity must be used. Results from tests on salmonids (the family of fish that includes salmon, trout, and other fish) must be used before tests on minnows, which must be used before tests on other animals.

Example databases:

Once you get sample test results from a database, you need to use the equation in the regulations (WAC 173-303-100) to calculate the equivalent concentration to compare it to the Toxic Category Table in the regulations.

Biological Testing Methods for the Designation of Dangerous Waste is a publication that describes testing requirements. For example, tests on fish must be conducted for at least 24 hours.

Washington Persistence Criteria
Wastes contain chemicals that are slow to break down. They linger in the environment and can accumulate in living tissue. There are two groups of Washington persistent wastes in the Dangerous Waste Regulations:

Polycyclic Aromatic Hydrocarbons (PAHs)
20 hazardous chemicals are identified as PAHs in the regulations (WAC 173-303-040). These are hydrogen molecules fused with two or more benzene rings. Wastes with more than 1% PAHs have the waste code WP03 and are considered Extremely Hazardous Waste (EHW).

Halogenated Organic Compounds (HOCs)
HOCs are any organic (carbon-based) compound with at least one atom of bromine, chlorine, fluorine, or iodine bonded directly to a carbon atom. For example, dry cleaning perchloroethylene solvent is a common HOC. HOCs are measured in parts per million (ppm). HOC wastes with total concentration greater than 100 ppm (0.1-1.0 percent) have a WP02 waste code. Wastes greater than 1.0 percent HOC content (10,000 ppm) are considered Extremely Hazardous Waste (EHW) and have a WP01 waste code.

Check your Safety Data Sheet (SDS or MSDS) and look for these chemicals or their prefixes (bromine, chlorine, fluorine, or iodine). For example, chloromethane. If you have compounds with those names, is it a halogen? If yes, you can assume it is dangerous waste or you can test it.

WPCB Code – Washington Polychlorinated Biphenyls
Polychlorinated biphenyls (PCBs) are very persistent—they last for decades in people, other animals, and the environment. In Washington, the WCPB code applies to undrained transformers, capacitors, and bushings containing PCB fluids with concentrations of 2 parts per million (ppm) or greater. It also includes certain wastes from salvaging, rebuilding, or discarding them. See the regulations (WAC 173-303-9904) for more information. Some of these wastes are excluded.

WSC2 – Solid Corrosives
A solid or semi-solid waste can designate as corrosive if its pH is within the corrosive range. To test pH, use a solution of 50% deionized water and 50% of your waste material (you need water to be able to test pH). It is corrosive if the pH is:

  • less than or equal to 2, or
  • greater than or equal to 12.5

Solid corrosives are not common. Cement or lime, for example, may test as corrosive.

Special Wastes
Special Wastes are a category of state-only excluded wastes with their own set of management requirements. They pose a relatively low hazard to human health and the environment. Special Wastes are solid phase wastes that are state corrosive, level D toxic, or non-EHW persistent. You may be able to recycle special wastes or dispose of them in municipal landfills (if you have the landfill authority’s approval). Learn more:

Contact a compliance specialist at your regional office with questions about designating or managing your dangerous waste.