F.O.G (Fats, Oils & Grease)

What is FOG?

FOG is an acronym for Fats, Oils, and Grease which is commonly found in wastewater.

Why is FOG a problem?

Fats in wastewater are among the more stable of the organic compounds and are not easily decomposed by bacteria so these fats coat, congeal, and accumulate on pipes, pumps, equipment and sometimes obstruct lines.

Is FOG a problem in Lakeport?

Yes, The City routinely performs maintenance on the collection system, lift stations, and treatment facility to remove grease, but maintenance is not enough to stop spills from taking place.

What can be done to Stop FOG?

Control FOG at the source…keep it from entering the sewer system.

  1. Best management practices (BMPs) can go a long way toward reducing FOG in the sanitary sewer system.
  2. Use pretreatment like grease traps or interceptors, skimmers, separators, and process flow treatment systems, such as carbon    filtration or coagulation units.
  3. The City’s sewer use ordinance provides regulations and enforcement provisions that will enable city staff to ensure that FOG does not create problems for local businesses and residents.

What is a grease trap and how does it work?

A grease trap is a small reservoir built into the wastewater piping, a short distance from a grease producing area. Baffles in the reservoir retain the wastewater long enough for the grease to congeal and rise to the surface. The grease can then be removed and disposed of properly. A diagram of a typical grease trap is presented below.



What is a grease interceptor and how does it differ from a trap?

First, we should clarify: the term grease interceptor is thrown around loosely and can refer to any type of wastewater pretreatment device for the purpose of collecting and storing fats, oils, or grease before that water reaches the sewer. It can also refer to a type of grease trap that is larger and slightly more complex than a standard device. As referred to here, a grease interceptor is a vault with a minimum capacity of between 500 and 750 gallons, located on the exterior of the building. The capacity of the interceptor provides adequate residence time so that wastewater has time to cool, allowing the remaining grease not collected by the traps time to congeal and rise to the surface, where it accumulates until the interceptor is cleaned. The figure below illustrates a typical grease interceptor.


If you have a grease trap or interceptor and believe that it may be ineffective at keeping FOG out of the sanitary sewer (i.e. needs frequent cleaning, backups occurring in kitchen, etc.), you may need to upgrade or replace your existing grease trap/interceptor. A grease trap/interceptor installation permit will be required for this as well.