A licensed hauler pumps the interceptor completely empty first, because nobody can see or reach a baffle, tee or wall under a grease cap and sludge. Then the tank is ventilated and tested, the repair crew inspects and fixes the parts, the tank goes back into service, and the owner logs the work.
Why does the hauler pump before the repair crew goes in?
Because the repair crew has nothing to work on until the tank is empty. Phoenix's FOG manual says the cleaning "must be performed by a licensed pumper" and that "The interceptor must be left completely empty upon completion of the pumping operation." It also says "The FOG mat, liquids, sludge and scrapings from the interior walls must be removed and disposed of at a licensed waste disposal facility."
That last part matters for the repair. The baffle, the inlet fitting and the outlet tee are submerged or buried in grease until the contents are out and the walls are scraped. San Antonio's utility, which requires an annual interceptor inspection, says it is made "After evacuation of the interceptor," when the inspector makes "a visual observation of all portions of the interceptor." Same logic anywhere: you cannot judge a part you cannot see.
Safety is the second reason. The tank is a confined space, and standing liquid and loose sludge add engulfment risk to the gas risk. Our page on why interceptor entry needs a confined-space crew covers that side.
Who is allowed to pump it?
Pumping is a separate licensed trade. HQ repairs and inspects grease interceptors but does not pump them, so the hauler is a separate company that you book first.
In Maricopa County, the county's code says "No person shall remove, store, transport, or dispose of any Nonhazardous Liquid Wastes without applying for and receiving a permit to do so." Each approved truck carries a county-assigned number. Our page on who can haul grease trap waste in Maricopa County lists what to ask a hauler before you hire one.
What are the eight steps, in order?
- 1Diagnose from outside. Check the records, the lid, the smell and how the tank has been draining. This tells you whether you need a repair crew at all or just a routine pump-out.
- 2Book the hauler and the repair crew together. The tank has to be open and empty when the repair crew arrives, and you do not want it sitting open any longer than it has to.
- 3Pump it completely. All of it: grease, liquids, sludge and wall scrapings. The NPCA's maintenance notes say to "Pump out the oil and grease from the top of all chambers" and to "Pump out the solids from the inflow chamber floor." Under Phoenix's manual the pumper may not "reintroduce the removed water or materials into the interceptor or the sanitary sewer."
- 4Witness it. Phoenix tells operators to watch the cleaning, and calls it "a good time to inspect for damaged or missing parts."
- 5Set up the entry. The cover comes off, the opening is guarded, the air is tested and ventilated, and the attendant and rescue gear are in place before anyone goes down.
- 6Inspect, then repair. The repair crew checks the baffles, tees, walls, floor and lid, then fixes what failed. Our page on what a plumber inspects in an interceptor lists the checks.
- 7Return it to service. The cover is reseated and the tank refills as the kitchen discharges. NPCA also notes that "Routine cleaning of the sewer line between the establishment and the interceptor will prevent this line from plugging," so this is a sensible time to find out whether the line leading to the tank needs jetting.
- 8Write it down. Keep the pump-out record and the repair record together.
Can the repair count as part of the scheduled pump-out?
Often, yes, and it saves a second visit. Phoenix City Code 28-15, as reproduced in the city's manual, says interceptors must be kept in "continuously effective operating condition at all times," which minimally requires "(1) periodic removal of all accumulated grease, lint, oil, sand, sludge, solids, wastewater, and other materials; (2) thorough cleaning of the pretreatment device interior; and (3) necessary repairs to internal structures." Repairs to internal structures sit in the same list as the cleaning. If you know a baffle is questionable, schedule the repair crew for the day of the next pump-out instead of paying for the tank to be emptied twice.
What if the repair is a replacement?
Then plan review comes first. The manual states that "all grease interceptors installed and replaced in the City of Phoenix must go through plan review," and that like-for-like replacements of hydromechanical interceptors can be submitted over the counter. A cracked or rotted gravity tank that has to be replaced is a project with a permit, not a same-day repair; read whether you need a permit to replace an interceptor before you book a pump-out for it.
What should the records show?
Phoenix's code says records "must be available at the facility or site for a minimum of 3 years from the date created and be made available to the Director upon request." Keep the hauler's invoice with the date, quantity and disposal site, and add the repair details: what was found, what was fixed and who did it. If your city is Mesa, its code puts the owner on the hook for "written records and documentation of all cleaning, repair, calibration, and maintenance." We cover the Phoenix list in what pumping records a Phoenix restaurant must keep.
HQ gives free estimates and upfront pricing on interceptor repair, and a licensed, insured crew handles the tank work once your hauler has emptied it.