Flammable or Explosive Materials

Flammable or explosive materials dumped in sewer lines have caused explosions that have killed and injured people and damaged property.

To prevent this hazard, King County prohibits certain pollutants from being discharged into the sewer system. These include, but are not limited to, gasoline, kerosene, naphtha, benzene, toluene, xylene, ethers, alcohols, ketones, aldehydes, peroxides, chlorates, perchlorates, bromates, carbides, hydrides, and sulfides. The pollutant may be anything that King County, the fire department, EPA, and Washington State recognize as a hazard.

Before discharging solutions containing any amount of flammable or explosive material to the sewer, contact the King County Industrial Waste Program to obtain a discharge approval. It is against the law to discharge such solutions without formal approval.

King County has the following local limits:

(1) No person shall discharge any pollutant, as defined in 40 CFR (Code of Federal Regulations) (external link) 403.5, that creates a fire or explosion hazard in any sewer or treatment works, including, but not limited to, wastestreams with a closed-cup flashpoint of less than 140 degrees Fahrenheit or 60 degrees Centigrade using the test methods specified in 40 CFR 261.21.

(2) At no time shall two successive readings on an explosion hazard meter, taken at the point of discharge into the system or at any point in the system, be more than 5 percent of the Lower Explosive Limit (LEL) of the meter nor shall any single reading be more than 10 percent of the LEL.