Grease trap pumping and cleaning around Oklahoma City

A grease trap does one job: it holds a kitchen's dishwater long enough for fats, oils and grease to float and food solids to sink, so the water that leaves is cleaner than the water that came in. It only works while there's room left in it. Once the grease cap gets thick and the solids pile up, grease goes straight through to the sewer line or, out past the city limits, into a septic tank and its lateral lines. This page covers what Oklahoma City's utility expects of a restaurant's trap, what a proper pump-out looks like, and why grease is even harder on a rural septic system.

Grease trap or grease interceptor?

The two words get used for the same thing, but they usually mean different sizes of box. A grease trap is the smaller unit, often set in the floor or under a three-compartment sink inside the kitchen. A grease interceptor is a large tank buried outside, sized for a whole kitchen's flow, with manholes at grade for the truck. The city's guidance covers both and treats them the same way: both have to be cleaned out regularly to keep working (City of OKC). A small indoor trap fills fast and is often cleaned on a short cycle; an outdoor interceptor holds more and is pumped by a vacuum truck.

What Oklahoma City requires

Oklahoma City's Utilities Department runs the sewer system that serves more than a million people through four treatment plants, and its commercial pretreatment program works with food service facilities to keep their waste out of the sewer mains (City of OKC). The city's page for restaurants spells out the rules for traps and interceptors (City of OKC, FOG and restaurants):

• Clean it regularly. Fats, oils, grease and solids must be cleaned from a grease trap or interceptor on a regular basis for it to work.
• Pump it out completely. Grease traps must be 100 percent pumped out. A quick skim off the top doesn't count.
• No decanting. Haulers aren't allowed to pour anything back into the trap or interceptor after pumping it.
• Use a permitted hauler. The city keeps a list of permitted transporters, and restaurants and other grease-producing businesses must use only those for cleaning and hauling grease waste.
• No enzymes or bacteria without approval. Enzyme, bacteria and other bio-remediation products are prohibited unless the city approves them first. The city's reasoning: unless conditions are ideal, these products break grease into shorter fatty acids that wash out into the sewer and recombine on the pipe walls downstream, which is the blockage they were supposed to prevent.

The city's page doesn't print a fixed number of days between cleanings, because a busy fryer kitchen and a coffee shop fill a trap at very different rates. If you're not sure what schedule the city expects for your kitchen, ask its Wastewater Quality Division, (405) 297-1610, before an inspector asks you.

What a proper pump-out visit includes

1. Everything comes out. The truck removes the floating grease, the water and the settled solids, so the box is empty, per the city's 100 percent rule. Nothing goes back in.
2. The walls and baffles get scraped. Hardened grease on the inlet and outlet baffles or tees narrows the flow path; a crew that only vacuums leaves it behind.
3. The parts get a look. Lids, gaskets, baffles and the outlet tee should be intact. A missing outlet tee lets grease leave with the water.
4. You get paperwork. Ask for a written record of each service: date, hauler, gallons removed and anything found broken. Keep them together. It's the first thing anyone asks for after a sewer backup, and the easiest way to show the trap is maintained.

Grease waste is its own category. Oklahoma DEQ's pumper program says domestic septage does not include grease trap waste (DEQ), so a company licensed to pump household septic tanks isn't automatically the right hauler for a restaurant trap inside the city. Ask whether they're on the city's permitted transporter list.

Grease and septic systems outside the city sewer

Plenty of kitchens around the metro aren't on city sewer at all: a cafe in Luther or Harrah, a church fellowship hall on acreage, an event barn west of Yukon. For them, grease is a septic problem first. EPA's septic owner guidance says never to pour cooking oil or grease down the drain, and that fats, grease and solids reaching the septic tank can clog the drainfield (EPA). A drainfield sealed with grease doesn't come back with a cleaning; in Oklahoma, replacing the field is treated as a new installation that needs DEQ authorization (our lateral lines guide explains why). A grease trap ahead of the septic tank, pumped on time, is far cheaper than that.

At home the same rule applies on a smaller scale: wipe pans into the trash, and keep up a pumping schedule. For the household tank itself, see septic tank pumping in Oklahoma City.

When to call

Call before it's a problem: when a trap is coming due, when drains in the kitchen start running slow, when there's a grease smell at the floor drain, or when the outdoor interceptor lid shows grease near the top. Tell us whether it's an indoor trap or an outdoor interceptor, roughly how many gallons, whether the building is on city sewer or septic, and the town. We pass it to an independent local company that handles grease waste, and they quote the job.

Frequently asked