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La Grange, Georgia Improves I&I with Flo-Dar Flowmeters

While a flowmeter training course brought Ricky Tucker from the City of LaGrange, Georgia's Sewer Department to Marsh-McBirney's (MMI) Maryland headquarters in the late 90's, it was a group discussion during the training that captivated his attention. According to Tucker, "When I came to Maryland for product training, MMI revealed their plan to introduce a revolutionary open channel flowmeter in the not-too-distant future." This new flowmeter, named Flo-Dar, would be the world's first radar velocity open channel flowmeter. The uniqueness of the Flo-Dar flowmeter was its ability to accurately monitor open channel flow without the need for submerged style flow sensors - a bona fide maintenance solution for Tucker and fellow department members.

Tucker, the I&I Inspections Coordinator for the City of LaGrange's Sewage Department, is well-versed in the pitfalls of monitoring flow in the rugged sewer environment. Submerged style flow sensors that were utilized to monitor wastewater flows were easy prey for fouling by debris resulting in frequent maintenance. While Tucker knew that the City of LaGrange had chosen the best open channel flowmeter available on the market at the time of its purchase, the mention of a new flowmeter that would accurately monitor flow without the need for submerged sensors resonated with him. Given the fact that MMI was the pioneer and worldwide leader in open channel velocity/area flowmeters, Tucker knew that this flowmeter advancement of "above-the-flow" flowmeters held great promise for the City of LaGrange's flow monitoring program.

The City of LaGrange, Georgia, population 26,000, is located 60 miles southwest of Atlanta. In the year 2000, LaGrange became the first city in the world to offer free Internet access for every citizen via cable television. Community leaders wanted to create a wired community that could compete in a high-tech world. The World Teleport Association recognized the city with the "Intelligent City of the Year" award for its Internet initiatives and advanced telecom infrastructure. The City also received a "Government Technology Leadership Award" from Government Technology magazine.

In the 1960's, when LaGrange's major industry, textiles, began to downsize, city leaders developed an industrial diversification plan. The plan would ensure that the city would never again be reliant upon just one industry. Today, over 11,000 employees work in 40 major industries throughout the city. LaGrange is now home to more Fortune 500 companies per capita than any other city its size.

The City of LaGrange made a clear commitment to keep up with changing technology and has invested significantly in emerging technologies and improved infrastructure to support new growth. As part of this plan, the stage was also set for the city's future growth relating to water production and wastewater treatment services. The city's water plant is permitted to operate at a capacity of 16 million gallons per day and currently averages 9 million gallons per day. The city's wastewater treatment plant, which serves 9,300 customers, processes an estimated 4 million gallons of wastewater per day and has a capacity of 12.5 million gallons per day.

In keeping with the city's growth plan, Tucker began a dialogue with department heads regarding the benefits that could be derived from the use of the Flo-Dar meters in the city's I&I program. While the flowmeters with submerged sensors would perform well in most of the city's applications, lines described as "heavily debris-laden" posed problems. The Flo-Dar flowmeters would easily and accurately monitor these "difficult to monitor" lines due to the remote sensor that monitored flow from above the fluid.

The Flo-Dar flowmeter combines digital doppler radar velocity sensing technology with ultrasonic pulse echo level sensing to remotely measure open channel flow. Flo-Dar is the perfect solution for difficult flow conditions including flows with high solids content, high temperature flows, caustic flows, large man-made channels, high velocities and shallow flows. Flo-Dar provides the user with highly accurate flow measurements under a wide range of flows and site conditions. By measuring the velocity of the fluid from above, Flo-Dar eliminates accuracy problems inherent with submerged sensors including sensor disturbances, high solids content and distribution of reflectors.

The Flo-Dar sensor transmits a digital doppler radar beam that interacts with the fluid and reflects back signals at a different frequency than that which was transmitted. These reflected signals are compared with the transmitted frequency. The resulting frequency shift provides an accurate measure of the velocity and the direction of the flow. Level is detected by ultrasonic pulse echo. Flow is then calculated based on the Continuity Equation: Q = V x A, Where Q = Flow, V = Average Velocity and A = Area.

Flo-Dar's unique ability to monitor flow from above the fluid, was the discriminating feature that led to the city's purchase of the flowmeters. The portability of Flo-Dar easily accommodates sewer department personnel who need to quickly install and remove flowmeters for the city's short term monitoring program. To date, six (6) Flo-Dar flowmeters are being used in the city's ongoing Inflow and Infiltration (I&I) studies. Tucker comments, "The Flo-Dars have worked out well for us. We are using them to detect I&I. The main thing we're doing is trying to locate the inflow and infiltration going into our sewer lines so we can get maintenance issues taken care of quickly." He further states, "Right now we are concentrating on one certain basin on the north side, an older area of the city. The longest period we usually monitor one site is about one month and then we move on to the next location. We are constantly moving the meters around from one location to another."

LaGrange's decision to include Flo-Dar meters in their wastewater flow monitoring program is just another example of their commitment to invest in technologies that will improve their infrastructure allowing for future growth. Plans to add additional meters are already in the works. Tucker adds, "We plan to get a couple of meters every year!"

City of LaGrange Inspections Crew (left) and Maintenance Crew (right).
From left to right Steve Lafevor, Tommy Davis, Jason Doss, Jimmy
Williams, Bobby Clay, Dion Senn, Chad Huber