A Significant Industrial User (SIU) is defined by the US Environmental Protection Agency (EPA) as an industrial user that discharges process wastewater into a publicly owned treatment works (POTW) and meets at least one of the following:

1. All industrial users subject to Federal Categorical Pretreatment Standards found in 40 CFR parts 405 through 471. 
2. Any other industrial user that:
   • Discharges an average of more than 25,000 gallons per day of process wastewater to the POTW (excluding sanitary, non-contact cooling and boiler blowdown wastewater) or
   • Contributes a process waste stream which makes up five percent or more of the hydraulic or organic capacity of the POTW treatment plant or
   • Is designated as such by the City of Greensboro Industrial Waste Section on the basis that the industrial user has a reasonable potential for adversely affecting the POTW's operation or for violating any pretreatment standard or requirement.
     
     

Industrial Waste Section Contaminants of Emerging Concern Policy

Useful Links for Determining if an SIU Permit is Needed:

State of North Carolina Pretreatment, Emergency Response, and Collection Systems Unit (PERCS) - Pretreatment Requirements / Information

EPA Effluent Guidelines

EPA: Federal Register Environmental Documents

Code of Federal Regulations (CFR), e-CFR

Significant Industrial User (SIU) Wastewater Discharge Permit Forms  

SIU Application

SIU Background Information and Additional Instructions

FAQs

For information about the SIU Wastewater Discharge Permit Application, please contact Amy Varinoski at 336-433-7227 or by email.