Partnering to Protect Clean Water

How Grease Blockages in the Sewer Occur

Sanitary sewers are designed and installed with sufficient diameter to carry the normal waste discharges from a residence or business. When fats, oils, and grease (FOG) are discharged to the sewer untreated, they cool and accumulate on the sidewalls of the sewer pipes.

Photo of sewer pipe obstructed by grease

Over time, this accumulation of grease restricts the flow and causes blockages in the sewer, back-ups on private property, and/or overflowing manholes. Sewer overflows can discharge to storm drains and creeks that ultimately flow to the Chesapeake Bay.

Sewer Overflow into parking lot caused by grease

How You Can Prevent Grease Blockages

Install and Maintain Grease Interceptors, Traps, or Grease Recovery Devices (Grease Treatment Units)

Properly installed and maintained grease interceptors, traps or grease recovery devices are the most important factors in preventing FOG discharges. There are several types of approved devices that can be installed by master plumbers licensed with WSSC. Ensure that all kitchen fixtures that may contain FOG are connected to the grease treatment unit. This includes wash sinks, prep sinks, dishwashers, spray sinks, and mop sinks. (Food waste grinders should not be connected to the grease treatment unit.)

Manual grease traps should be cleaned on a daily basis.

• Non-renderable grease contaminated with food and water may be placed in a trash dumpster in a sealed container or stored on site in a plastic barrel (labeled non-renderable grease) for removal by a grease disposal contractor.
• Do not put grease that is heavily contaminated with food and/or water in the grease rendering barrel.
• Keep a maintenance log on-site that documents the name of the person who cleaned the trap and the date of cleaning.

Manual Grease Trap

Automatic grease recovery devices have mechanical components, timers, and sensors that should be maintained at intervals recommended by the manufacturer.

• The grease collection container should be emptied daily.
• Maintain a log of cleaning and service that is performed on these units.
• When operating properly, grease from these units may be placed in a rendering barrel.
• If the recovered grease is heavily contaminated with water, the unit is not operating properly and should be inspected for necessary adjustments or repairs.
• Non-renderable grease contaminated with food and water may be placed in a trash dumpster in a sealed container or stored on site in a plastic barrel (labeled non-renderable grease) for removal by a grease disposal contractor.
• Do not put grease that is heavily contaminated with food and/or water in the grease rendering barrel.

Automatic Grease Recovery Device

Outside grease Interceptors should be pumped dry and cleaned on a monthly basis.

• Pumping must be performed by WSSC permitted grease disposal contractor.
• You can ensure that the work is performed correctly by going out and inspecting the cleaning job.
• WSSC regulations require that all liquids, solids and grease be removed from the interceptor.

Engineering Detail of WSSC Grease Interceptor

Waste Fryer Grease Disposal

• Waste fryer grease is a reusable commodity and should be disposed of in a covered metal rendering drum or "grease only dumpster." Maintain a log of fryer grease disposal by employees and the grease rendering company.
• Never pour waste fryer grease down the drain, into storm drains or on the ground. Make sure the barrel is covered at all times.
• Never leave the grease barrel dumpster open. Left uncovered they will collect rainwater, which will contaminate the grease and may cause the barrel to overflow into nearby streams.

Waste grease barrels

Waste grease dumpster

Cleanup Best Management Practices

• Instead of using food grinders, scrape food from dishes into waste cans before rinsing. This will greatly reduce the amount of grease and food particles entering the grease treatment unit.
  
  
• Dry-wipe pots, pans, kettles and any other large cooking utensils before washing. This will also reduce the amount grease entering the grease treatment unit.
  
  
• Mop water from floor cleanup should be emptied into a mop sink connected to a grease treatment unit.
  
  

Everyone Benefits

Working together, we can reduce the accumulation of grease in the sanitary sewer and associated blockages. This will ultimately benefit all parties involved. Restaurant owners will benefit by reducing the chance of sewer backups affecting their business operations. Homeowners will benefit by avoiding the unpleasant effects of backups, which cause a great deal of inconvenience and unsanitary conditions in their homes.

WSSC will realize reduced maintenance cost which ultimately benefits homeowners and restaurant owners as ratepayers. Most importantly, we will all be working together to help prevent pollution in the Chesapeake Bay and its tributaries.

Grease Treatment is Required by WSSC Regulations

Grease treatment is not only a good idea but it is required by WSSC regulations. All plumbing fixtures that may contain grease must be connected to a grease treatment unit that is maintained at regular intervals.

If you do not install and maintain grease treatment your business may be subjected to fines of up $1,000. If WSSC determines that grease discharges from your business are the cause of sewer blockages, you may also be billed for the property damage and restoration costs in affected homes or businesses.

For more information on WSSC's FOG Program or to obtain a wastewater discharge permit application, click here.