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Grease Interceptors

Posted by: Abram Richardson on Wednesday, June 29, 2016

Hydromechanical Grease Interceptor

Facilities with commercial kitchens, such as restaurants, schools etc. that produce grease-laden waste are required to have this effluent treated by an approved grease removal device before it is discharged into the utility/public sewer system. State and local mandates on grease interception are due to the costly impact that grease-laden waste (free floating fats, oils and grease) may have on public utility sewer systems, from pipe clogs to burned out pump motors at pumping stations.

Interception of grease-laden waste may be accomplished through the use of properly located and sized grease traps or grease interceptors which may operate hydromechanically or by gravity. State and Local codes may provide requirements for the construction and sizing of grease interceptors and often require a third party approval from the American Society of Mechanical Engineers (ASME), Plumbing and Drainage Institute (PDI) and or Canadian Standards Association (CSA). Gravity type interceptors are commonly used and sized to allow a minimum retention time of 30-minutes so as to allow free floating fats, oils and grease to rise to the top of the interceptor. Because of these operation and retention requirements, gravity type grease interceptors are typically larger than hydromechanical types of similar capacity and performance.

Regardless of the interceptor device used the designer needs to know some very important details about the facility and its operation including:

  • Type of facility (i.e. restaurant, cafeteria, Fast food or fine dining)
  • Type of foods that will be prepared (i.e. sushi, hamburgers and French fries or fried chicken)
  • Anticipated meals per day served
  • Hours of operation
  • Dishwashing operation (i.e. hand washing, door or conveyer style dishwasher, etc.)

There is ample information available for the design team to properly coordinate the size and location of grease interceptors to meet the needs of the respective State and Local Approving Agencies as well as the client. However all the research and coordination can be for not if the end user does not properly maintain the interceptor serving their facility. Just like other building systems grease interceptors require inspection and maintenance on a routine basis. This maintenance includes removal of accumulated fats, oils and grease on a 30 to 90 day cycle. The property owner should keep accurate maintenance logs detailing any repairs that are made as well as when the interceptor was last pumped. This information will allow the owner to make adjustments to pumping schedules and avoid any fines that could be issued by the local utility for insufficient grease removal.

Above: Two pre-cast concrete gravity type grease interceptors installed in series for a family style restaurant. The interceptors
are located in the back loading and parking lot area of the restaurant to allow easy access by the pumping contractor.

Above: A single hydromechanical type grease interceptor installed at a cocktail lounge style restaurant.
The interceptor is constructed of a polyethylene and manufactured by Schier Products. The light weight material
helps with reducing the installation cost. Photo used with the permission of Schier Products and RSL Sales.