Keeping Mesa pretreatment equipment running: City Code 8-4-21 records and bypass rules

Keep it running (A). Pretreatment facilities "shall be maintained continuously in satisfactory and effective operation by the owner at the owner's expense." The owner keeps written records of all cleaning, repair, calibration and maintenance required, at the facility, for at least three years.

Bypass is prohibited (B). All bypasses are banned except:

1. 1it is unavoidable to prevent loss of life, personal injury or substantial property damage,
2. 2no feasible alternative exists, or
3. 3the purpose is maintenance essential to efficient operation, and the bypass will not cause the exceedance of an effluent limit in an NPDES permit.

Notice (C). A permittee who knows a bypass is coming must give written notice to the City Manager or Water Resources Director at least 10 days before. For an unplanned bypass, notify them within 24 hours and send a written report within 5 days. The report covers the bypass and its cause and duration, whether it has been corrected (and if not, plans and time frames), and the steps to reduce, eliminate and prevent a repeat.

• Pretreatment facilities. Equipment that treats wastewater before it reaches the sewer, such as neutralization tanks, oil-water separators or equalization tanks.
• Bypass. Diverting wastewater around the treatment equipment. The section does not define it further.
• Permittee. The holder of an industrial wastewater discharge permit. Notice duties in (C) name the permittee.
• NPDES permit. The federal-state discharge permit system. The maintenance bypass test refers to its effluent limits.

Any owner with pretreatment equipment in Mesa, including a plumbing contractor who installs or services it on the owner's behalf, since the records they produce become the owner's records. The three-year records duty in (A) applies to the owner of the facilities. The notice steps in (C) name a permittee, so they follow the industrial discharge permit. Grease interceptors are governed by 8-4-22, which has its own record rules.

A lab neutralization system. The owner logs the weekly checks and the probe calibration in a binder kept at the facility. An inspector asks for it, and three years of entries are there.

A planned tank cleanout. The tank must be bypassed for maintenance. Ten days before, the permittee sends written notice. The bypass is allowed only if it does not cause an effluent limit exceedance.

The edge case. A float switch sticks and untreated flow goes around the unit overnight. The owner calls the city within 24 hours and files the five-day report with cause, correction and prevention steps.

1. 1List each pretreatment unit and what maintenance and calibration it needs.
2. 2Start a log at the facility and keep entries for at least three years.
3. 3Write a bypass procedure: who calls the city, with what information, and when.
4. 4Schedule maintenance so a planned bypass can carry 10 days notice.
5. 5If you plan changes to the equipment, ask Industrial Pretreatment first: 480-644-2484 or industrialpretreatment@mesaaz.gov.

• "The vendor keeps the records." The section puts the duty, and the location, on the owner's facility.
• "Maintenance bypass is always fine." Only if it will not cause an exceedance.
• "Ten days notice covers emergencies." Unplanned bypasses have the 24-hour and 5-day steps.
• "Repairs are the city's cost." Maintenance is at the owner's expense.
• "Records can be discarded after a year." The records the section requires are kept at the facility for 3 years.