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1. Where does FOG come from?

Even if you don’t deep fry food, FOG still occurs naturally in many foods, which leaves a residue behind on dishware that has been used to handle and prepare food. When dishware is washed with hot water and detergents the FOG residue becomes liquefied and is mixed with the dishwater. The mixed or emulsified FOG is then discharged with wastewater into your plumbing wastewater drain lines and, ultimately, to the City of Murfreesboro’s wastewater collection system by Food Service Establishments (FSE’s) such as restaurants, but is also discharged by other commercial FOG generators and residential dwellings, as well.

2. Why is FOG a problem?

FOG is a problem because, not only does it cause blockages in your wastewater drain lines, it also causes blockages in the City of Murfreesboro’s wastewater collection system and interferes with wastewater treatment facility processes, both of which can result in an overflow.

3. Do I need Grease Control Equipment (GCE), such as a Grease Trap, for my Food Service Establishment? What about my home?

Yes and no. Regardless of age, location, whether it’s an existing facility, a new development or a redevelopment project, all commercial FOG generators (non-residential facility engaged in the handling and preparation of food for consumption), such as Food Service Establishments, must be equipped with Grease Control Equipment, or GCE. Grease Control Equipment is typically not required for private residential dwellings unless it has been approved otherwise for commercial use such as catering.

4. Okay. So, I can just install a Grease Trap and I’m covered, right?

Not exactly because not just any type of Grease Control Equipment will do. Grease Control Equipment must be correctly sized and be of the appropriate type for each facility’s particular needs. The final size and type of Grease Control Equipment is determined by Murfreesboro Water and Sewer Department.

5. What is the first step I need to take to determine the size and type of Grease Control Equipment that I need?

The first step is to complete Murfreesboro Water and Sewer Department’s Wastewater Grease Interceptor / Trap (GrIT) application. For most Food Service Establishment development or redevelopment projects, the GrIT application must be submitted prior to receiving any building permits the Building and Codes Department.

6. How Does Murfreesboro Water and Sewer Department (MWSD) determine the proper size and type of Grease Control Equipment?

Murfreesboro Water and Sewer Department plugs specific information, supplied to us by Food Service Establishments via our Wastewater Grease Interceptor / Trap (GrIT) application, into our Grease Control Equipment (GCE) sizing worksheet, which, in turn, determines the proper size and type of GCE for each specific FSE. MWSD’s GCE sizing criteria is based on the EPA Procedure 2 model, but has been modified to meet WERF (the research arm of the Water Environment Federation) specifications.

7. What types of Grease Control Equipment (GCE) are accepted by Murfreesboro Water and Sewer Department?

Murfreesboro Water and Sewer Department prefers GCE that is installed on the exterior, more specifically a Grease Interceptor (GI). However, for establishments that meet certain criteria, GCE may be installed on the interior; but not just any type will do. The only GCE that is acceptable for installation on the interior is an Automatic Grease Recovery Unit (AGRU). Under no circumstances will Murfreesboro Water and Sewer Department permit the installation of passive Grease Control Equipment on the interior of any Commercial FOG Generator.

8. What is a Grease Interceptor (GI)?

A Grease Interceptor (GI) is similar to a grease trap in operation, but is much larger and is installed on the exterior, typically buried under ground. When a GI is specified, the minimum GI capacity required by Murfreesboro Water and Sewer Department is 1,000 gallons or equivalent (Schier Products GB-250).

9. What is an AGRU or Automatic Grease Recovery Unit?

An AGRU is an active type of grease trap. It is very similar in operation to a passive grease trap, except that it’s also equipped with a heating element and a skimming mechanism to physically remove the emulsified grease from the trap. AGRU’s require intervention by facility personnel on a frequent (typically daily) basis to properly maintain this type of grease control equipment.

10. Can I clean my Grease Control Equipment myself?

Yes and no. It all depends on the type of Grease Control Equipment installed. Grease Interceptors (GI’s) require service by individuals or companies that have large, specialized equipment capable of handling and legally disposing of large volumes of FOG. GI’s are typically serviced quarterly, or once every 90 days. Click here for a list of GCE Service Providers that serve the Murfreesboro area.

Automatic Grease Recovery Units (AGRU’s), on the other hand, are small by comparison and are easily maintained on a daily basis by Food Service Establishment personnel. Small volumes of recovered FOG can be recycled or disposed of with solid waste after mixing with an oil absorbent material such as cat litter.

11. Now that I know what size and type of Grease Control Equipment I need; and who needs to clean it, is there anything else I should know?

Yes. Prior to proceeding with the installation of Grease Control Equipment you should thoroughly review Murfreesboro Water and Sewer Departments FOG Management Policy (link). This will provide you with specifications regarding the installation and maintenance of all types of Grease Control Equipment.

Be advised that Grease Interceptor (GI) installations must not be backfilled prior to inspection; and Automatic Grease Recovery Units must be equipped with the manufacturer’s flow control device installed and vented on the inlet side of the unit. Please contact the FOG Program Coordinator to schedule inspections.