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Grease Trap/Interceptor 101

What is a Grease Trap/Interceptor System?

With a little understanding, good planning, and best practices for kitchen disposal, restaurant managers need not worry about emergencies that may close the doors and result in lost customers or potential fines from municipalities.

Restaurants are connected to city or county wastewater systems; all drainage from the kitchens are regulated by grease traps or interceptors, which capture the excess grease and oils from cooking and cleaning so that they do not enter the municipal wastewater supply. Restaurant owners must contract with licensed contractors like Burns Septic to have the grease traps and their lines cleaned regularly to avoid backups and stay in compliance with health inspections. Backups and clogs in the sewer lines can result in odors and the need to shut the restaurant down due to health issues, not to mention hefty fines from municipalities. Burns Septic TLC is here to help. With regular maintenance and our sound advice about best practices, your grease disposal system should remain problem-free so that you can focus on your other duties and serve the customers.

What It Looks Like

The photo shows a basic grease trap and its essential elements, as well as how things flow from restaurant to a city sewer system. The interceptor looks a lot like a septic tank.  The size of grease interceptors may vary from 750 gallons to 10,000 gallons; 1,200 gallons is a typical size grease trap.

How it All Works

The way to avoid problems is to prevent oil and grease from getting into the sewage system.  This is done by separating the gray water (kitchen wastewater) from black water (restroom wastewater) by installing a grease interceptor, or grease trap, to process the gray water and capture the grease.

Sinks, floor drains, dishwashers, and similar fixtures discharge their wastewater through a separate plumbing stub (inflow) out into the interceptor. After entering the interceptor, the wastewater flow naturally slows, allowing the lighter grease to separate from the wastewater and float to the top of the interceptor (where it cools). Thus, the grease tends to collect and float in the interceptor, whereas the filtered wastewater eventually flows out into the municipal water system through the main connection.

Maintenance Basics

Over time the grease will build up to a point where it needs to be removed. If not removed, grease will work itself into the sewer system, clogging the drain lines causing failure of the system. This creates problems not only for your restaurant, but for others down the line. As a big problem for city and municipal maintenance crews, it costs far more to correct a grease trap problem than to maintain it properly in the first place. Regular tank maintenance consists of routinely checking the grease level and periodically pumping the tank.  When the grease oil layer exceeds 1/4 of the tank capacity it should have already been pumped.  The threat of clogs, spills and environmental degradation increase drastically at this point.

Inflow and outflow lines, or drain lines, may also become clogged with buildup over time; the best method for cleaning these out is by drain line jetting. Jetting should be performed at least once a year to reduce the possibility of clogs that may affect municipal systems and result in stiff fines. (Burns maintains many different types of jetters for drain line jetting, which can be deployed to efficiently and quickly clear the system.)   The amount of time between cleanouts depends upon how many people are served and the degree to which you use the system, as well as whether you follow good practices for your system. Through the Sampling Box, you may make occasional tests to monitor the system and determine maintenance needs. The grease interceptor should be checked daily or weekly depending on the business and the grease thickness measured.  This can be done with a simple measuring rod.  If the grease layer is 1/4 the thickness of the entire trap/interceptor then the grease must be removed by an approved method.

Burns Septic recommends that commercial establishments consider our maintenance program for grease trap interceptors: contact us for details.


Recommended Links

We recommend the following outside links for additional information about grease traps, fats and oils and regulations.

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