Industrial Wastewater Pretreatment Permits by Valley City

Federal pretreatment rules (40 CFR Part 403) require cities that run treatment plants to control what industry sends them. Each Valley city writes that into its sewer use ordinance. Scottsdale says its Water Resources Division "will enforce federal pretreatment requirements as provided in 40 CFR Part 403."

Several cities share plants, so they coordinate. Scottsdale's code describes the SubRegional Operating Group as an agreement "among the City of Phoenix and the Cities of Scottsdale, Tempe, Mesa and Glendale." Gilbert's pretreatment facilities can face "a joint inspection by the director and the Cities of Phoenix or Mesa."

Five terms decide whether you need a permit.

• Significant industrial user (SIU). A user running a federally regulated process, or discharging large volumes. Phoenix, Mesa, Scottsdale and Gilbert all require SIUs to hold a discharge permit.
• Categorical standards. Federal limits for specific industries, such as metal finishing.
• Local limits. A city's own caps on pollutants like metals, set to protect its plant.
• Pretreatment. Treating wastewater on site before it enters the sewer, from a sand-oil interceptor up to an engineered treatment system.
• Zero discharge. A process that sends no process wastewater to the sewer. Scottsdale and Gilbert can still permit it.

More businesses than the word "industrial" suggests. Chandler's program covers "all non-residential users, i.e., Industrial Users (IUs)." Mesa's Class II and Gilbert's Class B reach users who aren't SIUs if the city finds their discharge could harm the sewer, workers or the environment.

Restaurant grease interceptors also fall under these chapters and have their own installation and maintenance rules. A grease interceptor does not settle whether a particular operation also needs a wastewater discharge permit; the city classifies its discharge. See grease interceptor records and inspections by city.

The order matters, because a building permit application can stall if the pretreatment review hasn't happened.

Phoenix is explicit: "Construction drawings and engineering design manuals for industrial manufacturing or industrial servicing facilities must be submitted for review and approval by the City of Phoenix Industrial Pretreatment Program (IPP) prior to submittal to the City of Phoenix Planning Development Department."

Avondale says plans "shall be acceptable to the director before such facilities are constructed." Tolleson says "All pre-treatment systems shall require an engineering design and have plans prepared and signed by an engineer of suitable discipline licensed in the State of Arizona."

Scottsdale is the outlier. Its Water Resources Division "will review, but not approve, plans and specifications for all pretreatment facilities," and the city checks building code compliance separately.

A brewery opens in Scottsdale. If it counts as a significant industrial user, the permit application is due "at least one hundred and eighty (180) days prior to the date upon which any discharge will begin." That clock runs in parallel with the build-out, not after it.

A Gilbert plant adds a production line. Gilbert says anyone "intending to commence any new industrial discharge, or any additional industrial discharge not already allowed pursuant to an existing permit, shall apply for a new or amended permit at least 90 days prior to initiating such discharge."

A Mesa shop gets a letter. It isn't an SIU, but the city names it in writing as a risk and its discharge exceeds "the equivalent strength of twenty-five thousand (25,000) gallons per day of domestic waste." That makes it Class II, and it needs a permit.

Start with the city, not the plumbing plans.

1. 1Find your city's pretreatment program and ask whether your process needs a permit. Phoenix posts a flowchart for this question.
2. 2Count the lead time backward from opening day: 180 days in Scottsdale, 90 in Gilbert.
3. 3Get pretreatment plans reviewed first. In Phoenix that happens before the building plans go in; in Tolleson an Arizona-licensed engineer signs them.
4. 4Plan for inspection access at the sampling point or control manhole the permit names.
5. 5Tell the city before changing the process. Gilbert requires a new or amended permit for any additional discharge, and Avondale wants significant pretreatment changes accepted before they start.

• "Only factories need a permit." Chandler covers all non-residential users, and Mesa and Gilbert can permit non-SIUs.
• "The building permit covers it." The discharge permit comes from the water or wastewater department, on its own timeline.
• "Scottsdale approved our plans." Scottsdale reviews them but says "Approval of plans and inspection by the City shall not relieve the industrial user from complying."
• "Permits last forever." Mesa's run no more than five years and can't be transferred.

The discharge can't start legally. Scottsdale says any user required to have a permit "must apply for and obtain such permit prior to commencing such discharge." Mesa permits are "nontransferable by the permittee," so a new owner needs its own.

This page explains the rules; each city's pretreatment program and its staff govern. HQ installs and repairs sand-oil interceptors and process drain piping for commercial and industrial buildings across the Valley, with free estimates and 24/7 service.