Many cities require restaurants and other food-service establishments to install concrete grease traps, also known as grease interceptors, to keep waste food fats, oils and waxes from clogging sewer systems. These lidded concrete boxes have interior baffles that separate and trap grease from waste water, holding it for disposal. Many localities require that grease trap installations be done by a licensed professional; however, some may allow you to do your own grease trap installation.
Instructions
1. Consult with your local plumbing department to determine the size grease trap you must install. Concrete grease traps are sized by your wastewater volume.
Decide where you will place your grease trap. It must be installed upstream from the point where your toilets drain into the sewer.
Obtain a plumbing permit and get local site approval if required. Call your state or city utility-locator service to have your excavation site checked for underground utility lines. If the site is paved, remove the concrete or asphalt paving over the site, slicing it up with a concrete saw for easy removal.
2. Excavate a hole several feet wider, longer and deeper than the dimensions of your grease trap. Cut out the section of your building's wastewater outfall line that crosses the hole.
Haul most of the dirt away with a dump truck. Keep about one-third of the dirt for backfill. Line the bottom of the hole with 1 foot of 3/4-inch gravel. Compact the gravel with the vibrating compactor.
3. Lift the grease trap off the delivery truck and lower it into the hole, centering it. Orient it so the trap's outlet is on the same side as the city sewer pipe. Your supplier should have a delivery truck or other equipment that can place your grease trap into the hole.
Stack the grease trap's concrete manhole rings over the access holes to bring the holes up to grade level. Seal them according to local codes or the trap manufacturer's directions. Install a manhole cover at the top of each stack of rings. Obtain interim plumbing approval if required.
4. Backfill with more gravel all around the grease trap until you reach halfway up the sides. Compact the gravel. Connect the building's wastewater outfall line to the inlet side of the grease trap and the city sewer to the outlet side, using sewer pipe and connectors required by local codes. Obtain final plumbing approval.
Backfill with soil around the trap. Compact the soil after every 4 inches of vertical filling. Continue filling and compacting until the grease trap is completely covered and the fill is up to grade level. Finish with concrete or asphalt if the site is paved. Lay sod if the site isn't paved.
