Fats, oils and grease (FOG) are a significant contributor to the problem of sanitary sewer overflows (SSOs) in the United States, and many municipalities are working to reduce their impact on their systems through pipe cleaning and FOG programs.
Cities are developing and implementing FOG programs as a way to control the amount of material that enters their systems — material that creates a sewer line nightmare for the public utilities works departments and their customers in terms of cost and maintenance.
One such city is Virginia Beach, Va. The FOG program (vbgov.com/fog) here is relatively new, but its Department of Public Utilities believes it is the best way to rid their sewer pipes of FOG and thereby reduce the number of SSOs that occur in the system. Developed as a pilot program in 2006, the city recently received the go-ahead from its city council to implement the program citywide. In its early stages, the program is projected to save the city thousands of dollars as it cuts down the number of SSOs affecting its system and customers.
“We estimate that approximately 30 percent of our sanitary sewer overflows are caused by FOGs,” said Steve Motley, SSO reduction bureau manager of Virginia Beach Public Utilities. “And another 20 percent of the time, FOG are a contributing factor.”
The results of the Virginia Beach FOG program has aided in the reduction of SSOs in recent years: from 192 in 2003 to 34 in 2009. This reduction has netted Virginia Beach a savings of approximately $1,500 per SSO event.
Major contributors to sewer line blockages are the fats, oils and grease generated from food service establishments, residential homes and multi-family dwellings — and most of these folks don’t even realize they are contributing to the SSO problem, Motley said. What it came down to in Virginia Beach was better dissemination of information about the impact of FOG to its customers and enforcement of the codes already in place, Motley said.
Its concerted efforts to rid its sewer lines of FOGs in combination with its pipe cleaning program have the City of Virginia Beach tackling its SSOs head on. How are they doing it?
A FOG program is designed to reduce the number of sanitary sewer pipe blockages and related overflows by teaching people how to properly dispose of their fats, oils and grease. Why is that important? The proper disposal of fats, oils and grease in the sewer system can build up and eventually block collection pipes and sewer lines, resulting in backups and overflows on streets, properties and even in homes. Sewer overflows are not only unsanitary but they are costly in terms of cleanup and repairs.
Virginia Beach, with a population of more than 430,000, is a popular resort city with hundreds of hotels and restaurants along its miles of beaches. Being a hot spot for tourists all year-round, problems with its sewer system is not an option and its officials work daily to improve, upgrade and maintain its 1,900 miles of gravity mains, forcemains, laterals and vacuum sewers. The Virginia Beach system is not unlike systems all across the United States — it’s aging and in need of ways to be maintained without breaking the budget.
The oldest parts of the Virginia Beach sanitary sewer system were built in the 1950s, with the majority of it being built during the 1970s. Approximately half of the city’s pipes are made of vitrified clay, with the other half a mixture of PVC and ductile iron.
The sewer system conveys an average of 35 million gals of wastewater per day to two sewage treatment plants operated by the Hampton Roads Sanitation District (HRSD), whose service area includes 17 cities and counties of southeast Virginia.
“Generally speaking, the system is in ok condition,” Motley said. “We rehabilitate and replace pipes on an as-needed basis annually through our Find-and-Fix program. We used to rehabilitate on a whole neighborhood basis, doing one at a time but because money has gotten tighter and the needs have increased, we have shifted to a more focused approach. We let our programs dictate where the needs are and tell us where the problems are.”
The programs that Motley refers to include the Find-and-Fix Program, as well as the SSO Abatement and Resolution Program, Inflow-and-Infiltration Abatement and Emergencies Program and general CCTV and smoke testing investigations. In addressing the system’s needs, Virginia Beach has utilized trenchless methods such as cured-in-place pipe (CIPP), fold-and-form and manhole relining.
One area that has concerned the Department of Public Utilities was the impact that fats, oils and grease have on its system. “FOG is the single-greatest cause of SSOs in our city. Roughly half of our SSOs in some way, shape or form are related to FOG. That was the primary driver of the program,” Motley said, noting the other 50 percent was due to structural pipe defects, roots, etc.
Historically, the HRSD provided the primary enforcement role related to the discharge of FOG in the sanitary sewer system through its Pretreatment Program and its NPDES permit. But because Virginia Beach owns and maintains the collection system and is responsible for SSOs from its system, the Department of Public Utilities decided to develop its own FOG program that is complementary to HRSD’s program through extensive collaboration with the district.
Periodically, gravity collection mains become blocked with grease, debris and/or roots, which lead to customer service calls and SSOs. It also leads to problems with the pump stations. “We have more than 400 pump stations,” Motley said. “I haven’t seen a pump station yet that doesn’t have a grease issue.”
In 2005, the city began CCTVing SSOs and collecting data on the system. The city also began networking with other cities that have FOG programs to learn what steps they took to combat the problem and what components were part of the solution. From that, a plan was developed and a pilot program began in 2006, targeting a small commercial section of the city.
“When speaking with other localities about their program, education and public outreach seemed to be the two biggest factors for success. They learned that most business owners, managers and residents had no idea of their impact as far as FOG disposal,” said Toshia Martin, project manager for the SSO reduction bureau.
As a result of their research with other cities, Virginia Beach met with their stakeholders — members of the restaurant association, motel association, grease haulers, property management groups, department of health, assisted living associations, daycare providers and public schools — on a regular basis to let them know what was going on and to get their feedback. They also came to the same realization as other locales: there was a lack of understanding by the general public regarding the use and maintenance of grease control devices. By including the public in their plans, Motley said it was much easier to get them onboard with the program.
Beyond education and outreach, another key component to the FOG program is the routine cleaning and inspection of the city’s sanitary sewer lines. “Cleaning the pipes is probably the single most effective tool we have,” Motley said.
Virginia Beach works on a reactive and proactive pipe cleaning program. The reactive facet is when someone calls to report a sewer stoppage and crews respond to determine the problem and clear it. Following the cleaning, CCTV inspection takes place upstream and downstream from the overflow location, with crews looking for any defects in the line that may have caused the stoppage. On the proactive side, city crews clean the lines on a set schedule and frequency — either monthly, bimonthly or annually — and televise the pipes afterward to check for grease buildup. They began the proactive cleaning program in 2006.
“In 2009, we cleaned 660,000 lf of pipe,” Motley said.
The Department of Public Utilities — which does its pipe cleaning in-house — has six mainline cleaning trucks that are a combination of Vactor and Vac-Con units, as well as a smaller mainline cleaning truck (Vac-Con). Crews also have four Rapid Action Clean Environment (RACE) trucks that are used as first responders to customer calls and are capable of cleaning lateral stoppages. All of the mainline cleaning trucks are equipped with Duke’s Jetpower II Degreaser units. The department also has two CCTV trucks that utilize RS Technical equipment and the POSM software package.
Motley and Martin believe once the FOG program is rolled out for the entire city and with continued maintenance of its pipes, the number of SSOs will continue to come down. But in advising other cities, both say critical to any success is to engage their stakeholders in the process.
Sharon M. Bueno is managing editor of Trenchless Technology.