Grease Traps and the 25% FOG Rule

January 15, 2018 Posted By Matt O'Brien

grease trap

The people who operate restaurants and other places involved in food production must be very thankful for the invention of the grease trap. In use since the time of Queen Victoria, the grease tap has proven to be very effective at reducing the amount of FOGs or fats, oils and greases that make it from the kitchen to the major drain pipes. If grease traps were never invented, you can only imagine how clogged drains would be with all the FOGs restaurants and other commercial kitchens produce and dispose of every single day.

However, useful as grease traps might be, their capacity is limited. Sure, there are grease traps that can hold 45,000 litres of FOGs, but no matter how big a grease trap is, the time will come when it will fill up, which is why it must be cleaned periodically, lest it violate the 25% FOG rule stipulated in local and state regulations with regards to wastewater.

What is the 25% FOG rule?

Simply put, the 25% FOG rule, which applies to grease traps as well as interceptors, specifies that the combined FOG and solids that accumulate inside the grease trap or interceptor do not exceed 25% of its total design hydraulic depth.

To be able to comply with the 25% FOG rule, operators of establishments that have grease traps or interceptors should fully clean or pump them out as needed. That way, the minimum hydraulic retention time and required available hydraulic volume is maintained in order to effectively intercept and retain FOG that is entering the sewer collection system.

Frequency of Grease Trap Cleaning

Now the question is, how often should you clean your grease trap or interceptor? Obviously, your cleaning schedule will heavily depend on the system that you have and how much FOGs you dump into it. As with anything else, always set a certain benchmark.

Initially, clean the grease trap on a prescribed schedule and take note of the amount of FOG removed. At the same time, estimate the amount of FOG that has been discharged into the system during the same time period. In just a few months, you will finally be able to set a benchmark and make it easier for you to determine how frequent the grease trap cleaning should be.

Then again, cleaning up a grease trap or an interceptor is heavy and messy work. If you want to avoid cleaning the grease trap frequently, the best thing you can do is set up a system or a process that would keep the FOG out before it enters the wastewater system. That way, FOGs won’t accumulate and force you to clean it just so you won’t violate the 25% FOG rule for your grease trap.

Still, there is always the possibility that with the grease trap you have right now, you are going to have a hard time complying with the 25% FOG rule. If this is your current situation with regards to your grease trap, you can always call us. Give us a call, and we’ll help you set up a better grease trap that will comply with any regulations being implemented locally and state-wide.

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