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FOG Case Study from Boone, NC
Boone, North Carolina, is a small town of around 25,000 residents and university students, nestled in the Blue Ridge Mountains at an elevation of 3,333 feet. It is a popular outdoor adventure and relaxation destination as well as the home of Appalachian State University (Go Mountaineers). With more than 170 restaurants, cafeterias, nursing homes, day care centers, schools, and other food service establishments (FSEs), the Fats, Oils, and Grease (FOG) program is a busy one.
Karen Reece is the Lab Supervisor/Pretreatment Coordinator for Boone. She’s been working there for more than 20 years. They implemented their FOG program with a city ordinance in July of 2008. The ordinance includes connecting all fixtures and drains in the kitchen, food and beverage prep and bars areas to the grease removal device. In that time, she’s seen many improvements at the wastewater treatment plant, reduced maintenance of the collection system, and reductions in Sanitary Sewer Overflows (SSOs).
From 2007 (before the FOG program was implemented) to 2019 (when it was going “full steam”), the foam layer on the oxidation ditches thinned considerably, which was attributed to less grease entering the plant. The influent wet well no longer has floating “potatoes” either. There is a grit and grease removal unit after the influent pump station. The removed materials are disposed along with the bar screenings. The receiving landfill provides the tonnage for each load. Correcting for population growth only, the average lb/d/person went from 0.05 lb/d/person in 2004 to 0.02 lb/d/person in 2019. The total tons/year dropped from 160 to <100 in that same time period. There may be other factors involved with this reduction, but the FOG program is certainly a contributing factor.
Collection system maintenance has been reduced since the FOG program was implemented. The first hot spot tackled in 2008 is the most dramatic, but other hot spots have had similar results. The collection system crews used to have more SSOs at a manhole in the local university's park...at least one per year, give or take. There hasn’t been an SSO there in years. Upstream of that location, grease buildup had to be treated and jetted often. They hardly ever must do that now. The worst offender is now on a weekly pump-out of a 1000-gallon gravity grease interceptor (GGI) to maintain the 25% FOG capacity rule. Prior to implementation of the FOG inspection and enforcement program, they were pumping approximately quarterly. Contributing also to that area were several restaurants without any grease removal, including some located at the university's student union. Some restaurants installed GGIs, some chose Hydromechanical Grease Interceptors (HGIs), and all of them now pump-out at frequencies maintaining 25% FOG or less in the grease interceptor (GI).
Getting FSEs to understand and comply with the proper pump-out frequency took a few years. Initially, all the existing FSEs in town needed to be on-boarded to the program. Educational materials included information on the problem with FOG, best practices, the costs of FOG, what types of establishments were required to comply, and how to get more information. Once full participation was accomplished, there was time to do periodic inspections to check whether the pump-out frequency being used at each FSE was adequately maintaining the GI at 25% capacity or less. Measurements were made approximately two-thirds to three-fourths of the way into pump-out cycle. Appropriate follow-up activity established better pump-out frequencies where necessary. This follow-up work occurred less often every year and things were going smoothly by 2019. Then Covid hit and inspections and enforcement measures used to ensure pump-out frequency adherence were scaled way back. There were a couple of hot spots that developed in the last few years during this reduced enforcement. Renewed enforcement began in June 2022. It took some time due to some staff changes, requiring training, but compliance with proper pump-out frequencies is nearly back to 100%. Periodic inspections this year do not cover all FSEs as they did in the past but will be done upstream of any of the newly identified problem spots.
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