Biodiesel Storage Regulations

Underground storage tank (UST) regulations apply to all biodiesel blends with the exception of 100% biodiesel (B100). If a UST owner increases the percentage of biofuel in a petroleum UST, they must prove that all UST materials are compatible with that product. UST owners must submit an Alternative Fuel Installation or Conversion Checklist when the percentage of ethanol in gasoline is greater than 10% or the biodiesel percentage in diesel is greater than 20%. For more information, see the Department’s Biodiesel in Underground Storage Tanks fact sheet.

(Reference Washington Administrative Code 173-360A)