Significant Industrial Users are defined as:

• All Industrial Users are subject to categorical pretreatment standards outlined in 40 CFR Chapter I, Subchapter N, parts 405 - 471.
• Any other industrial user that: discharges an average of 25,000 gallons per day of process wastewater (excluding sanitary and 'dilute wastewater', as defined at 40 CFR 403.6 e(1)(i) under 'FD'); contributes a process waste stream which makes up 5% or more of average dry weather hydraulic or organic capacity of the publicly-owned treatment works; or is determined to have reasonable potential for adversely affecting the publicly-owned treatment works' operation or for violating any pretreatment standard or requirement.

Significant Industrial Users' New User Pre-Discharge Requirements

Federal law requires that industrial users proposing to discharge wastewater to the sewer system from operations subject to categorical pretreatment standards must submit a completed Significant Industrial User Discharge Permit Application, Toxic and Prohibited Organic Chemical Management Plan (All SIUs) and a completed Baseline Monitoring Report no less than ninety (90) days before the proposed date of initial discharge.

Upon receipt of the application, new dischargers are scheduled to attend a pretreatment conference, where operations will be performed, and proposed pretreatment technology will be reviewed.

Additional Related Forms

• Supplemental Application for Pharmaceutical Research, Development, and Manufacturing Facilities 
• Signatory Authority Confirm or Delegate 

Significant Industrial Users Permit Requirements

• Standard Conditions 
• Discharge Prohibitions 
• Appendix A - Definitions 
• Local Limits