How often must a Scottsdale car wash or repair shop pump its interceptor?

Section 49-95 of the sewer code says grease, oil or sand interceptors shall be provided by laundries, restaurants, service stations, auto repair shops, carwashes and other industrial users when, in the opinion of the Water Resources Division, they are necessary. It excludes domestic users. Interceptors must be of a type and capacity the city approves, easy to reach for cleaning and inspection, watertight, and fitted with gastight and watertight covers.

The owner maintains the interceptor at the owner's expense and keeps written records of cleaning, repair, calibration and maintenance at the facility for at least three years. The Pretreatment page repeats the three-year records rule and adds the yearly pumping line quoted in the key facts above, plus "more pumping and cleaning may be necessary" depending on discharge.

Section 31-85 adds IPC 1005.5: all fats, oil, grease and sand interceptors with a capacity over 100 gpm/200 pounds must be completely cleaned at least once every 90 calendar days, and smaller ones every 30 days. It says cleaning must be by a licensed contractor. The same section says facilities shall be inspected and that domestic wastewater and water above 140 degrees Fahrenheit or below pH 5.0 cannot go to an interceptor.

• Sand/oil interceptor: a multi-stage tank that holds back dirt, debris and automotive fluids so water and oil can separate before the water reaches the sewer.
• Fleet service facility: the city's phrase for a yard that maintains its own vehicles. The page does not define it further.
• "Sand interceptor" in Section 1005.5: the code does not say whether a car wash or shop sand/oil interceptor falls under it. Reading it that way is a reasonable interpretation, not stated law.
• Necessary: Section 49-95 leaves the decision to the Water Resources Division. A shop has no automatic right to skip the device.

Car washes, repair and body shops, radiator shops, fleet service facilities and laundries, whichever the city finds needs an interceptor. It does not cover home garages or residential washing. The person responsible is the owner, even if a tenant runs the shop.

A mobile detailing yard with a large sand/oil tank. The city page reads as once a year. The code reads as every 90 days for a large sand interceptor. Both agree on records and on pumping sooner when needed.

A quick-lube shop that pumped in March. The yearly statement alone does not establish compliance: pumping may be needed sooner because of discharge conditions, and the applicable code interval may be 90 days. Ask the city which schedule applies before relying on next March.

The edge case: no drawing of the device. A landlord cannot tell whether the tank behind a tenant space is sized 100 gpm/200 lb or less, or above that rating. The size decides which interval applies, so find the label or the approved plans.

1. 1Find the interceptor's rated capacity on its label or the approved plans.
2. 2Ask Scottsdale Water Quality Pretreatment in writing which interval it holds your facility to, and keep the answer with your records.
3. 3Until you have that answer, plan on the stricter number, and hire a licensed hauler.
4. 4Log every pump-out with the date, hauler, invoice and what was done, and keep the log on site for three years.
5. 5Keep the cover watertight and accessible, since Section 49-95 requires easy access for cleaning and inspection.

• "Yearly is the law." That is the city page. The code text in Section 31-85 reads 90 days for sand and grease interceptors above 100 gpm/200 pounds.
• "Only restaurants need an interceptor." Section 49-95 names laundries, service stations, repair shops and car washes as well.
• "Every Valley city uses the same interval." Neighboring cities differ. Glendale uses 180 days, and Gilbert does not set an interval in its vehicle facilities section.

This page summarizes the city's rules. The adopted text on Municode governs.