FOG Frequently Asked Questions

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FOG Frequently Asked Questions2018-01-24T20:39:15-05:00
Where does FOG come from?2018-01-24T20:32:51-05:00

Does your facility cook meat, serve soups or salad dressing? Do you use butter, margarine or oil in food preparation? Fats, oils and grease (FOG) are abundant in and on the foods we eat.

When foods are prepared, oils and greases are cooked out of the food or added as ingredients or non-stick remedies. The FOG ends up on cookware, dishwater, kitchen equipment and floors. During the cleaning of the equipment and floors, the FOG can enter the plumbing system. Shortly after this occurs, the FOG begins to cool and separate from the dishwater. After separation, the FOG will begin to accumulate in the building piping system and the public sewers. It is no coincidence that plumbers are called frequently to restaurants to unclog blocked lines.

Why is FOG a problem?2018-01-24T20:42:54-05:00

Sewer capacity reduction, increased maintenance costs, shortened infrastructure lifespan, sewer overflows and backups, odor and many other issues to the environment are a few of the reasons why FOG is a problem.

Most wastewater collection system blockages can be traced back to FOG as the cause. Blockages in the wastewater collection system are serious, causing sewage spills, manhole overflows and sewage backups in homes and businesses.

Large amounts of FOG in the wastewater causes decreased pipe capacity in the collection system, resulting in increased maintenance costs and premature pipe replacement.

FOG also can cause treatment issues at the wastewater treatment plant. In a liquid form, it does not appear harmful. As the liquid cools and the grease congeals, it creates thick grease mats on tanks, piping and equipment, which causes treatment problems and higher maintenance costs.

What is a grease trap and how does it work?2018-01-25T07:24:30-05:00

A grease trap is a small reservoir built into the wastewater piping, a short distance from the grease producing area. Baffles in the reservoir retain the wastewater long enough for the grease to congeal and rise to the surface. These small devices need to be cleaned often, from daily to weekly, and this is normally done by restaurant staff. Some plumbing and septic hauling companies also offer grease trap cleaning services.

What is a grease interceptor and how does it work?2018-01-25T07:26:27-05:00

A grease interceptor is typically a concrete vault with a minimum capacity of 750 gallons. It is connected to the restaurant plumbing and is located below the ground and outside the building. The interceptor capacity allows for enough retention time for the suspended FOG to congeal and rise to the top. Periodically, a service contractor will pump the accumulated grease and other food waste out of the receptor to maintain its efficiency.

Do I need a grease interceptor or trap?2018-01-26T13:24:21-05:00

YES! Facilities that prepare and serve food produce FOG and need a grease removal device. Grease interceptors are the preferred grease removal device of the Columbus City Utilities for a number of reasons:

  • They are larger, providing more retention time for the grease to congeal and separate fro the wastewater.
  • Some of these devices can accept discharge from dishwashing machines and food grinders.
  • Grease interceptors are located outside and are less likely to create offensive odors inside the restaurant.
  • They are cleaned by outside contractors every 30 to 90 days, eliminating the need to depend on staff to maintain the device.

Indoor grease taps can be effective in certain applications, but must be maintained frequently and can’t be connected to some commons kitchen fixtures and equipment. For example, grease traps cannot be connected to food grinders or dishwashing machines. Grease traps are appropriate for small, low volume restaurants with limited dishwashing and kitchen equipment.

What if I do not have a grease trap?2018-01-25T07:32:52-05:00

If you operate a non-residential facility that prepares and serves food, you need a grease removal system. Do not wait until you experience problems with block lines or sewer backups at your facility. You can contact the Columbus City Utilities to learn how to become compliant.

The Columbus City Utilities will work with your facility to ensure that you have installed the proper equipment and are using it efficiently. There may already be a grease trap or interceptor installed at your facility of which you are not aware. There are also some simple steps that can be done that will significantly reduce or eliminate FOG from entering your plumbing system.

What about inspecting the grease traps and interceptors?2018-01-26T13:26:38-05:00

There is a 25% standard rule for determining acceptable levels of waste that accumulate in your grease trap or interceptor. This means when the trap or interceptor has accumulated waste accounting for 25% of its wetted depth, the device needs to be cleaned.

Businesses may find that preventing FOG from entering their plumbing systems and City sewers will save money by reducing plumbing related problems.

Establishments that fail to comply with the Columbus City Utilities FOG management policy by discharging FOG to the City sewers could be required to install additional grease removal equipment or may be fined for non-compliance.

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