Food Safety Concerns: Grease Traps
Food Safety and Grease Traps
Grease traps are essential components of a food service operation. Grease must be removed from a garbage disposal, dish sink or dish machine, before it can accumulate downstream and cause a backup of wastewater. If the grease trap is not the proper size, installed in the correct location or cleaned regularly, it may be useless. This blog posting discusses grease traps, how to choose the correct design and location and how to maintain them properly.
A grease trap or grease interceptor, is basically a metal box designed to intercept wastewater flow, allowing heavy solids to separate to the bottom and cleaner wastewater to flow through to the sewer. Several pictures of grease traps in this article. Grease traps work by slowing down the flow of warm, greasy water, allowing it to cool. As the water cools, the grease and oil separate and float to the top of the trap, while heavier food solids sink to the bottom. The remaining wastewater exits the trap and continues to the sewer system.
The size of a grease trap is critical. If the trap is too small, grease solids will flow through the system, creating clogs and the backup of wastewater. An oversized grease trap will not function properly; grease will not separate to the bottom. The size should be calculated based on the gallons per minute flow rate for faucets producing grease laden wastewater (garbage disposal, dish sink, food preparation sink). The size may also vary depending on the volume of water generated in the food service facility. A grease trap can easily fill up in a high volume facility.
Figuring the total water flow and corresponding grease trap size can be complicated. One method is to calculate the time required to fill a bucket of one or five gallons. The easiest method, and often the only legal method, is to hire a certified plumber and work with the local health authority. Plumbers and regulatory agencies often have software to figure out the total water flow and the corresponding grease trap size. There also will be regulations dictating the size of the trap as well as the location.
The location of a grease trap can cause problems as well. Installed too close to a grease generating faucet, the grease flows through the trap and is not intercepted. Installed too far away and the grease clogs pipes and never enters the trap at all.
Grease traps should be cleaned when they fill to one quarter of their total capacity or every one to three months. In some areas, there is a time requirement to clean every ninety (90) days regardless of use. The failure to clean grease traps routinely can lead to foul odors, driving away customers, or worse, the failure of the grease trap to work properly.
Grease is considered a hazardous waste, whether it is produced inside the food service or accumulates in an outside collection device such as a dumpster or grease barrel. Leaks or overflows can lead to fines from regulatory agencies.
In addition to wastewater backups, leading to citations and fines, the failure to clean grease traps frequently can lead to corrosion from the buildup of acids due to decomposing food. As a result, the grease trap might not work properly. Maintenance is a difficult job best left to professionals.