Grease Reduction & Pretreatment
When wastewater pipes become blocked by oil and grease, a common result may be sewer overflows. Sewer overflows can have potentially serious environmental health impacts. The easiest way to help prevent overflows is to minimize grease disposal into the collection system from homes and restaurants.
Industrial Pretreatment Program
The Industrial Pretreatment Program is federally mandated by the Clean Water Act of 1977 and subsequent re-authorization. This Act requires the elimination of the discharge of pollutants into our nation’s waters. The Industrial Pretreatment Program is a component of the National Pollutants Discharge Elimination System (NPDES) Permitting Program developed under this act; the program monitors industry for regulated pollutants discharged into the sanitary sewer system in order to protect public health. Because certain industrial pollutants are not compatible with wastewater treatment procedures, it is necessary to protect the water reclamation facilities’ systems through pretreatment. This helps to ensure that pollutants do not pass through the city’s treatment plants and impact our environment.
Grease Reduction Initiative
The industrial pretreatment program is also responsible for the current grease reduction initiative. Fats, oils and greases improperly disposed through the sanitary sewer system are a major cause of sewer line blockages and overflows. By working with all customer classes to reduce/eliminate grease in the system, staff will reduce the impact of grease on the system.
Grease is singled out for special attention because of its poor solubility in water and its tendency to separate from the liquid solution.
The Problem with Oil and Grease in Pipes
Large amounts of oil and grease in wastewater can cause problems in collection system pipes. Grease sticks to the insides of sewer pipes, both on your property and in the streets. This decreases pipe capacity and, therefore, requires that piping systems be cleaned more often and/or replaced sooner than otherwise expected. Oil and grease also hamper effective treatment at the wastewater treatment plant.
Any type of grease, whether from businesses or residences can cause serious problems that may result in raw sewage backups and overflows in your homes or in the street. Sewer overflows pollute our rivers and streams, increase our risk to coming in contact with disease-causing organisms, and increase the costs of operation and maintenance of sewer lines and wastewater treatment.
Residents can help reduce these risks by following these simple dos and don’ts.
- Collect cooking oil and grease in containers and dispose of it properly (used residential cooking oil can be properly disposed of at the City’s Waste Disposal and Recycling Center at no cost)
- Keep grease out of wash water
- Place food scraps in a waste container for solid wastes
- Remove oil and grease from kitchen utensils, equipment, and food preparation areas with scraper/towels/broom
- Pour oil or grease down the drain
- Use hot water to rinse grease off surfaces
- Use the drain as a means to dispose of food scraps
- Wash fryers/griddles, pots/pans, and plates with water until oil and grease are removed
- Annual Sewer System Report (PDF)
- City of Durham Sewer Use Ordinance
- Commercial Guide to Grease (Restaurants) (PDF)
- General Sewer Use Requirements
- Industrial User Wastewater Survey and Permit Application (DOC)
- NC Department of Environment and Natural Resources Division of Pollution and Prevention
- Avoid the Grease Monster (WMV)
The Problem with Nonwovens
The vast majority of nonwoven products (even those labeled as “flushable”) do not readily decompose in the sewer system. Nonwovens alone, or along with improperly disposed of cooking oils in the sewer, can cause major problems. A clog can have a bigger impact than you may think, causing Sanitary Sewer Overflows (SSO) in your community or even your own home. Your water and sewer funds are used to deal with this problem! Dispose of items properly in the trash and eliminate the problem!
Remember that the drain and toilet are not a trash cans!