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Industrial User Permits

I. Significant Industrial User

Significant Industrial Users (SIUs) are defined as:

  • All Industrial Users (IUs) subject to categorical pretreatment standards set forth at 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 wastestream which makes up 5 percent or more of average dry weather hydraulic or organic capacity of the POTW treatment plant; or is determined to have reasonable potential for adversely affecting the POTW's operation or for violating any pretreatment standard or requirement.

SIU 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 (PDF) and a completed Baseline Monitoring Report no less than ninety (90) days prior to the proposed date of initial discharge. Where categorical pretreatment standards include a Total Toxic Organic (TTO) 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.

SIU Permit Requirements

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