What Is a "Significant Industrial User"?

The term Significant Industrial User (SIU) means:

• All industrial users subject to categorical pretreatment standards, known as categorical industrial user(CIU).

• Any other industrial user that:

  • discharges 25,000 gallons per day or more of process wastewater to the POTW (excluding sanitary, noncontact cooling and boiler blowdown wastewater)

  • contributes process wastewater to the POTW which makes up 5 % or more of the average dry weather hydraulic capacity of the wastewater treatment plant

  • contributes process wastewater to the POTW which makes up 5 % or more of the organic capacity of the wastewater treatment plant

  • or is designated as such by the POTW on the basis that the industrial user has a reasonable potential for adversely affecting the wastewater treatment plant's operations and sewer system or for violating any pretreatment requirement.

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