Grease traps are an important part of a kitchen's wastewater drainage system and are required by most municipalities to be installed at all food establishments.  Their purpose is to minimize grease blockages within the municipal sanitary sewer system. Some jurisdictions regularly issue citations for failure to properly maintain a grease trap.  Wastewater from sinks, dishwashers, and floor drains contains significant amounts of fats, oils, & greases (FOG).  This ‘oily' water flows through drain pipes that lead to the grease trap. The grease trap's job is to reduce the velocity of the incoming wastewater, allowing it to cool as it flows through the trap. This gives the FOG a chance to float to the top where it remains until removed by one of AWR's vacuum trucks.  As wastewater continues flowing into the grease trap, cooler ‘degreased' water flows under the trap's baffles and through the outlet into the municipal wastewater collection system.  If the device is working properly, most of the FOG that was in the original incoming wastewater gets ‘trapped', saving taxpayers thousands of dollars in mostly preventable cleanup of downstream sewer blockages.

Grease traps are sized based on the expected flow and grease content in the incoming wastewater. For example, a 4' x 4' x 2' trap might be sufficient for a grocery store bakery, but the meat department of a grocery store would require a much larger unit. Restaurant grease traps are usually sized according to the number of seats present. Local building codes and wastewater treatment plants may have grease trap ordinances that require minimum sizes for grease traps, periodic cleaning, and random inspections.

There are various designs of grease traps. They can be purchased preformed or they can be designed according to local plumbing code standards. Usually, water enters the influent side of the tank which is divided from the effluent side with a baffle located 2/3 of the way from the influent end. Water flows under the baffle via an opening about 1/3 of the distance down from the top of the tank. One vendor sites a general indicator for determining clean out frequency by measuring the grease layer thickness. The rule of thumb is that a grease trap needs cleaning when the floating grease mat exceeds 3/4" to 3" in depth or when the sludge layer on the bottom exceeds several inches in depth. The free water layer between the grease mat and the sludge layer should make up the majority of the depth of a properly functioning grease trap. If a grease trap has dimensions of 4' wide x 4' long and several feet deep, the maximum volume of FOG that the tank should hold is about 30 gallons. Monitoring the thickness of the grease mat will allow the restaurant operator to determine clean out frequency. The grease mat thickness can be measured by extracting a ‘core' sample using a 3'' diameter pipe. While twisting, press the pipe through the grease mat. Pull the pipe out of the grease mat and knock the core out of the pipe to measure thickness.

• Inspect grease traps to determine if they are installed correctly. One grease trap cleaning service found that about 25% of all grease traps are installed backwards!
• Many restaurants have installed food grinders to allow for disposal of food waste in the drainage system. However, waste food grinders should not be installed ahead of a grease trap since the ground food will fill the trap with sludge, rendering it inoperable or inefficient at best.
• Small, automated traps that drain FOG into a container for recycling can be installed downstream of dishwashers and sinks.
• Install strainers on sinks, dishwashers, and floor drains to prevent large solids from entering grease traps. Rubber gloves, silverware, towels, lids, caps, and rocks should NEVER find their way into grease traps, yet AWR sees these items routinely.
• Make sure your grease trap's manhole covers are secured and maintained in good condition. Open or broken manhole covers coupled with greasy surfaces is a recipe for a lawsuit. Be careful!
• Never dispose of grease by intentionally pouring it down the drain. Instead, place it in a recycling container for AWR to pick up when your grease trap is pumped. CAUTION: Never pour hot FOG into a plastic container! Metal is always safer.
• If a grease trap is undersized, it will not retain FOG. If no grease mat is forming at the top, have the trap evaluated to determine if it is properly sized, properly installed, and meets building codes.
• Never dispose of solid wastes by placing them in a drain. Keep drain strainers secured at all times. They are there for a reason.
• Reduce your liability. Keep records of when and how much FOG is collected, when grease traps are inspected, when and who cleaned the grease trap, and where the material from the trap is taken. AWR proudly recycles FOG into environmentally friendly products.
• Disposal of used oil and residues from grease trap cleaning is regulated by most municipalities. Most landfills will no longer accept FOG unless it passes a ‘paint filter' test (it must be de-watered). Recycling is the best approach to FOG management.
• Grease traps should be designed and located so that water leaving the trap has an opportunity to cool, allowing grease to rise to the top and solidify before effluent is discharged from the grease trap's outlet.
• Grease traps and common sense grease management are still required if you have a septic tank. FOG buildup in septic systems may require costly repairs. Building and sanitation codes often require grease traps to be installed even when disposing of wastewater in on-site septic systems.

Large amounts of grease can quickly lead to trouble in drainage systems. Problems caused by grease and oil from restaurants cause establishments to have blockages and back-ups. Solidified grease adheres to pipes' inner walls. This decreases a pipe's carrying capacity and requires it to be cleaned more often and/or replaced sooner than expected.

If your establishment uses oil or grease in food preparation, you will eventually have problems with your pipes backing up. This can lead to a health hazard at your establishment. You will have to pay for the removal of the blockage if the problem is in your building's sewer line. If the blockage is in the public sewer main and your establishment is proven to be the cause of the blockage, you will have to pay for the public sewer to be maintained.

The most important thing to remember is to properly maintain your grease trap and drain lines. Work out a preventive maintenance program for your grease trap and drain lines. All grease traps need to have the grease cleaned out periodically. AWR has never seen a ‘silver bullet' chemical, bacterial, or aeration treatment perform as promised. The best performing grease trap is a regularly pumped grease trap. No one likes to do it. It is a dirty job. Running hot water down your drain will only move the problem further down the drain. It will not just go away. Such ‘methods' may be interpreted by inspectors as willful negligence and you may be held liable for damages if the municipality determines your restaurant is the source of the problem.

Once grease reaches the sewer system, it sticks to the insides of sewer pipes, accumulating into a hardened mass. Over time, excessive buildup can block the entire pipe and cause a sewer overflow. Sewer overflows are health hazards, they damage interiors of buildings, and they threaten the environment. Do the right thing. Have your grease trap pumped regularly. Call Greg or Kelly Jarvies today to put your establishment on a routine maintenance schedule.