Gravity Grease Interceptors: Managing FOG
Leon Holt, Utility Pretreatment Coordinator, Cary, N.C.
Claude Goguen, P.E., LEED AP, NPCA
Thursday, December 13
Noon – 2:00 p.m. Eastern
Sanitary sewer collection systems and decentralized treatment systems comprise a valuable part of the nation’s infrastructure. Communities across the U.S. are working to find cost-effective, long-term approaches to managing aging wastewater infrastructure and preventing problems that lead to sanitary sewer overflows (SSO). There are many potential causes of SSOs, including full or partial blockages due to the accumulation of fats, oils and grease (FOG) deposits. Much of the FOG found in sewer pipes can be traced back to food service establishments and various means of separating that FOG can be used. One of those means is the gravity grease interceptor – a tank located outside the establishment that is intended to separate and hold the FOG using time and gravity.
A WERF study titled, “Fats, Roots, Oils, and Grease (F.R.O.G) in Centralized and Decentralized Systems,” was published in 2008 along with two companion documents containing data on the performance of gravity grease interceptors. The webinar presenter, Leon Holt, was the pretreatment coordinator for the Town of Cary, N.C., and a principal investigator on this study. During this webinar, Holt will reference this study as he discusses the chemical nature of FOG. How different is FOG based on the establishment and specific cuisines? How does FOG vary on a national scale? He will also discuss the issue of illegal dumping. Holt will also cover topics relating to construction materials and gravity grease interceptor sizing that considers far more than just daily flow and retention time. This webinar is intended to provide useful information to environmental and health department professionals.
At the conclusion of this course, you will be able to:
- Explain the general differences in FOG chemistry based on location and type of establishment.
- Identify key factors that should be considered when designing and sizing gravity grease interceptors.
- Explain the basis of the Town of Cary sizing formula and use that information to reexamine formulas contained in their respective jurisdictional rules.