Below are questions commonly asked about the Commercial Fats, Oils & Grease program.

Commercial FOG Program Frequently Asked Questions

1. What is FOG (Fats, Oils & Grease)?

FOG stands for Fats, Oils and Grease. FOG includes cooking oil, butter, margarine, bacon grease, dairy cream, and other fats typically used in cooking. They can be liquid or solid.

2. What is the Commercial FOG Program?

The City of Columbia has a Commercial FOG Program. The program requires Food Service Establishments (FSEs) discharging into the City's sewer system to use properly sized grease traps or interceptors to limit the levels of FOG in their sewer discharge.

3. Why does the City have a FOG program? How does the City benefit from it?

The Commercial FOG Program helps protect the City's sewer system and equipment in the wastewater treatment process. This program is also required by the United States Environmental Protection Agency (40 CFR 403).

FOG that enters the City's sewer system can clog gravity sewer lines and air release valves. These clogs can cause pump station failures that lead to Sanitary Sewer Overflows (SSOs). By reducing the levels of FOG discharged into our sewer lines, FSE's can aid in preventing clogged sewer lines and equipment failures, ultimately reducing the number of SSOs.

4. How do sewer customers benefit from a FOG program?

Limiting the amount of FOG levels entering the City's sewer system helps reduce costs related to maintaining the sewer system. The City spends a significant amount of money and man-hours unclogging and cleaning waste water collection lines. Because these costs are passed on to City customers through our sewer rates, the less the City has to spend on FOG related-issues, the less these costs are passed on to the customer.

5. Where does the City get the authority to limit what goes into its sanitary sewers?

Standards and limitations on materials that may be discharged into the City's sanitary sewers are established in the City Code of Ordinances, Chapter 23, Article IV, Sections 23-101 through 23-115.

6. How long has the City had a FOG program?

The City has done periodic inspections of grease traps for many years under the authority granted in the City Code of Ordinances, Chapter 23, Article IV, Sections 23-101 through 23-115.

In 2009, these periodic inspections were expanded into the Commercial FOG Program. The first full-time FOG inspector was hired and began inspecting in the spring of 2009.

7. Has there been an improvement in the number of sanitary sewer overflows caused by grease?

Yes. The City saw a 10% decrease in the number of SSOs caused by grease alone or by grease and roots between the 2008-2009 fiscal year (July 1, 2008-June 30, 2009) and the 2010-2011 fiscal year (July 1, 2010-June 30, 2011).

8. Who is affected by the FOG program?

Any FSE that regularly prepares food, whether for on-site consumption like restaurants and schools, or for late consumption, like grocery stores, has the potential to add FOG to our sewer system. Under Sewer Use Ordinance Sec. 23-114, these businesses need to have proper structures and procedures in place to prevent FOG from entering our sewers.

9. Doesn't DHEC already inspect grease traps for the food-service industry? Why does the City also inspect grease traps?

SCDHEC and the City both inspect grease traps for different reasons. The City inspects grease traps to determine if they are functioning and/or being used properly to reduce the levels of FOG entering the sewer system and to ensure maintenance is being performed. The City inspection does not cover food handling practices. Food handling inspections fall under the jurisdiction of SCDHEC.

10. What is required of regulated businesses?

Under Sewer Use Ordinance Sec. 23-114, FSE's need to have proper structures and procedures in place to prevent FOG from entering our sewers.

Structure Sizing: The sizing requirements are based on the type of FSE and the amount of food prepared in addition to the degree of customer traffic. FSEs can use the Grease Trap Sizing Guide PDF document to determine how large the structure should be. The structure should be sized to prevent any water or waste containing more than 100 mg/L of FOG from entering the City's system.

Maintenance: FSEs need to develop proper operation and maintenance procedures for maintaining their grease traps and grease interceptors.

11. What do FOG inspectors look for?

Inspectors will need to look inside the grease trap or interceptor. They will inspect the level of grease in the structure and determine if proper maintenance is being performed. They will also look at the outlet tee to determine if there is any grease being discharged into the sanitary sewer.

If the inspector finds any visual issues with the system, they will ask to look at the maintenance logs to determine the last time the system was serviced in order to ensure maintenance activities are being performed. The records review will determine if the City requests that a FSE increase its maintenance schedule or develop a routine schedule if needed.

A Maintenance Log for Cleaning XLS document template is available for download.


1136 Washington St.
Columbia, SC 29201


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