Seeing Through the FOG - The NCSD’s Master Plan for Fats, Oils, and Grease


  • Olivia Flynn PE - Hazen and Sawyer
  • Jarred Jones PE - North Charleston Sewer District

Fats, Oils, and Grease (FOG) accumulates in the North Charleston Sewer District’s (NCSD) collection system causing sanitary sewer overflows (SSOs); reduced capacity, float failures, and odor concerns at pump stations. Currently, the NCSD removes the accumulated FOG from pump station wetwells, which results in significant costs associated with cleaning and disposal. Due to these concerns, the NCSD is preparing a FOG Master Plan to identify a system wide approach to prevent and reduce FOG accumulation in the collection system. Once completed, the primary focus of the Master Plan will include recommendations to alleviate FOG accumulation at 44 of the NCSD’s pump stations that experience significant FOG accumulation issues. A secondary focus will be to collaborate this effort with the NCSD’s Cease the Grease FOG Program. The Master Plan will leverage the industry’s top elimination or reduction solutions, and include a process that allows for implementation of recommendations taking into account NCSD’s prevention programs already in place.

As part of this effort to date, the NCSD and Hazen Team have completed their evaluation of the following:

  • FOG quantification and characterization;
  • FOG prevention initiatives including public outreach and standards for food service establishments (FSE);
  • FOG removal alternatives including biological and chemical treatment and physical removal;
  • FOG emulsification alternatives including chemical treatment and mechanical mixing; and
  • FOG ultimate disposal options.

The first task in the development of the Master Plan determined the potential sources of FOG throughout the service area. Information was gathered to review FSE compliance with the NCSD Grease Trap standards and effectiveness of the NCSD’s Cease the Grease FOG Program. As part of the second task, the Team then quantified the system wide FOG volumes; quantification is an important evaluation criterion for assessment of FOG impacts on existing facility operations and for the proper design of specific handling and treatment solutions. The third task identified and evaluated all applicable FOG elimination or reduction methods for the collection system in a means to select the appropriate solution for each pump station. Currently, the Team is in the process of identifying the elimination solution for each pump station based on the best and most cost-effective solution. Ultimately, the FOG Master Plan will serve as an instrument to develop and rank a list of potential projects.

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