Significant Industrial Users (SIU)- includes

  1. All categorical industrial users, and
  2. Any noncategorical industrial user that
    1. Discharges 25,000 gallons per day or more of process wastewater excluding sanitary, noncontact cooling water and boiler blow down wastewaters
    2. Contributes a process wastestream which makes up five percent or more of the average dry weather hydraulic or organic (BOD, TSS) capacity of a treatment plant, or
    3. Has a reasonable potential, in the opinion of the Control or Approval Authority, to adversely affect the POTW treatment plant (inhibition, pass-through of pollutants, sludge contamination, or endangerment of POTW workers)