Significant Industrial Users (SIUs) are industrial waste producers that, by federal definition, require a specific level of regulatory attention. SIUs must meet self-monitoring and reporting requirements for effluent limitations, sample collection, reporting schedules, record keeping, and hazardous materials management.

Each SIU must submit an application to discharge industrial wastewater to the City’s sanitary sewer system. SIUs meet any one of the following criteria:

Categorical SIUs are subject to Categorical Pretreatment Standards under 40 CFR 403.6  and 40 CFR Chapter I, Subchapter N. Any industrial user in business areas subject to Categorical Pretreatment Standards is considered to be a Categorical SIU. 

Non-Categorical SIUs are subject to federal reporting requirements, but are not subject to categorical pretreatment standards. They also:

  • Discharge an average of more than 25,000 gallons per day of industrial waste
  • Contribute a process waste stream that makes up 5% or more of the average dry weather hydraulic or organic capacity of the city's wastewater treatment plant.
  • Have a reasonable potential for adversely affecting the city's treatment plants or collections system operations, or for violating pretreatment standards or requirements.