Do you need an industrial wastewater discharge permit in Mesa? City Code 8-4-16 and 8-4-18

Section 8-4-16 sets the classes:

• Class I. "All significant industrial users shall be Class I industrial users."
• Class II. Not a significant industrial user, but the city has decided in writing that the discharge causes or could cause harm to the sewer system, worker safety, public safety or the environment, and it meets at least one test: discharge above the strength of 25,000 gallons a day of domestic waste (measured by BOD and suspended solids), pollutants from groundwater under an approved cleanup plan, any substance banned in 8-4-15, or no discharge (or domestic only) but significant quantities of pollutants that would be regulated if discharged.
• Class III. Everyone else.

Section 8-4-18 then requires Class I and II users to get the permit. Mesa must issue it within 60 days of deciding an application is complete. It lasts up to five years, can't be transferred, and can be amended. It names the discharge limits and monitoring and reporting duties. Class I permits also carry required pretreatment.

• Significant industrial user (SIU). Defined in 8-4-1: every user under a federal categorical pretreatment standard, plus users that discharge an average of 25,000 gallons a day or more of process wastewater (not counting sanitary, noncontact cooling or boiler blowdown), contribute 5 percent or more of a plant's average dry-weather capacity, or are designated by the city. A categorical user discharging 100 gallons a day or less may be treated as nonsignificant if the city so finds.
• Process wastewater. Mesa's definition is water that touches, or results from, a raw material, product, by-product or waste during manufacturing or processing.
• Pretreatment. Treating wastewater on site before it enters the sewer.

Any Mesa business that discharges to the city sewer and lands in Class I or II. A permit is only required for facilities with process wastewater or a categorical process, so a typical office, shop or restaurant is Class III. Restaurants deal mostly with grease interceptor rules instead.

A food processor opens in Mesa. The city sends new businesses a survey. If the plant produces process wastewater at the SIU thresholds, it lands in Class I and needs the permit.

A warehouse with drums of solvent. No production water goes down the drain, yet if the city finds the quantity of pollutants is a risk, the no-discharge test can make it Class II.

The edge case. A shop is Class III for years. The city then finds its discharge could harm the sewer and writes that finding, and it becomes Class II and needs a permit.

1. 1Fill out the Industrial/Commercial Survey from the city's Discharge Permit and Pretreatment Forms page.
2. 2Call Industrial Pretreatment at 480-644-2484 or write industrialpretreatment@mesaaz.gov to get your class.
3. 3If Class I or II, submit the Industrial Pretreatment Discharge Permit Application. The city has 60 days from a complete application.
4. 4Plan any sampling ports, flow monitoring or pretreatment the permit will list.
5. 5Give the city at least 90 days notice before an expansion, production increase or process change that could raise or alter the discharge.

• "A permit is expensive." The city says permits are free of charge, though a quarterly monitoring charge may follow, based on wastewater strength or volume.
• "It transfers with the business." It doesn't. A new owner needs their own.
• "No discharge means no permit." The no-discharge test in 8-4-16(B)(3)(d) can still land you in Class II.
• "Only factories are covered." Class II reaches smaller users the city has singled out.

Skipping it has consequences. The city says a facility operating without a permit may face civil and criminal action.