Fats, Oils, Grease (FOG)

Fats, Oils, Grease (FOG)

Grease is a problem for all of us. It doesn't break down in water and tends to separate from other liquids. This can cause problems in your pipes and ours.

As our community grows, so do the demands on public infrastructure. Sewer lines and pump stations require more frequent maintenance, wastewater treatment costs rise and sanitary sewer overflows still need to be prevented.

Oil and grease from kitchen drains accumulate in the pipe system. As grease cools, the fat hardens and pipe capacity decreases. This requires more frequent cleaning and increases maintenance costs at treatment plants. Backups in your home or business are costly, but can be reduced when you implement best management practices to keep grease out of your sink and drains.

    1. Why do FOG pretreatment systems matter?

Proper installation, use and cleaning of grease interceptors can help save time and money and ensure compliance with the local sewer use ordinance.

All fixtures and drains in food service areas must be connected to an appropriately sized grease interceptor and be on an effective pump out maintenance schedule. FSEs must also ensure FOG doesn't enter the stormwater system through open trash enclosures or improper practices. When FOG enters a stormwater catch basin, it discharges directly to local creeks, wetlands and rivers – and violates the Clean Water Act.

    2. How can I be sure I am in compliance with the ordinance?

  • Connect all food and beverage service area faucets and drains to an appropriate-sized grease interceptor.
  • Maintain your grease interceptor to prevent FOG bypass accumulation before storage capacity is full.
  •  Keep maintenance records for inspection by city staff.

    3. What is FOG Best Management Practices?

  • Keep wash practices in areas that don’t drain to a storm catch basin. Only rain water should enter the storm drain.
  • Scrape all FOG and food solids from dishware and cookware into trash before washed.
  • Install properly sized screens for all drains to prevent solids and foreign objects from getting into the sanitary system.
  • Don't use degreasers or emulsifiers in your building sewer system.
  • Clean vent hoods and filters as needed.
  • Prevent spillage when transferring cooking oil to an outside oil waste bin.
  • Cover trash enclosures. If there is a catch basin in the trash area it should be coved and connected to a grease interceptor.

    4. Do I need a grease interceptor?

Yes, if your facility qualifies as a Food Service Establishment as: "A facility that engages in activities of preparing or serving food or beverage for consumption either on or off the premises, including but not limited to restaurants, cafes, commercial kitchens, caterers, hotels/motels, schools, hospitals, prisons, correction facilities, nursing homes, care institutions, and any other facility preparing and or serving food/beverage shall have a Pretreatment system (Grease Interceptor) to protect the public sewer."

    5. What is a grease interceptor and how does it work?

A grease interceptor captures wastewater discharge from fixtures and drains in a food/beverage service area and is connected to the building sewer. A grease interceptor is intended to slow the wastewater discharge long enough (retention time) for the FOG and food solids to separate from the gray water. The FOG floats to the top and food solids sink to the bottom, allowing gray water to pass through to the public sanitary sewer system properly.

The gray water discharge travels through conveyance (pipes/pump stations) and on to a wastewater treatment plant for processing. Grease interceptors need to be installed so that all areas that contact wastewater can be properly maintained and visually inspected.

    6. What types of grease interceptors can be used?

The food/beverage service industry utilizes two main types of grease interceptors:

  • Gravity Grease Interceptor (GGI) is a large vault made of concrete or plastic. It has the largest FOG storage capacity with at least two internal chambers and is installed outside. A gravity grease interceptor allows wastewater to reach the first chamber, the inlet bay. It is where FOG and food solids are stored and separated from the gray water through retention time process. The gray water then continues on to the second chamber, the outlet bay, for further separating. The outlet bay is not intended to store FOG, but to provide an indicator of service needed to comply with the Local Sewer Use Ordinance.
  • Hydromechanical Grease Interceptor (HGI) is smaller and made of plastic or metal. HGI uses an internal baffle system with flow control to hold wastewater in the building sewer until the HGI has time to process (retention time) FOG and food solids from the gray water. This process can lead to a FOG buildup in your building system. HGI needs easy access for maintenance and visual inspection.

It's important to note:

  • FOG storage capacity will determine long-term maintenance costs.
  • Consider capital costs (short term) vs maintenance costs (long term)

FOG Cover Letter 2023

FAQ Regarding FOG

FOG Submittal Checklist

FOG Permit Application

FOG Program Manual