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 and a completed Baseline Monitoring Report no less than ninety (90) days before the proposed date of initial discharge. Where categorical pretreatment standards include a Total Toxic Organic chemical discharge limit, a completed Toxic and Prohibited Organic Chemical Management Plan must also be submitted.

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

Significant Industrial Users Permit Requirements

• Standard Conditions 
• Discharge Prohibitions 
• Local Limits 

Related Links and Documents

• 40 CFR 136 (EPA Approved Methods for Industrial Wastewater Analysis)
• 40 CFR 400-424
• 40 CFR 425-471
• Appendix A - Definitions 
• Signatory Authority Confirm or Delegate 
• Signatory Requirements 
• Pre-Discharge Letter 
• Baseline Monitoring Report 
• Toxic and Prohibited Organic Chemical Management Plan