Clayton County, Georgia Makes Dreams Come True with Flo-Dar

Clayton County, Georgia, located just minutes south of downtown Atlanta, is one of the stateâs smallest counties in land size but is one of the most densely populated.  The Clayton County Water Authority (CCWA) services the water needs for this growing community of approximately 250,000 people. CCWA operates two water production facilities, four wastewater reclamation facilities, one wetlands center, and three community facilities. CCWA produces 32 million gallons of potable water and treats 27.6 million gallons of wastewater per day through a system of distribution mains 1,130 miles long.

Prior to the start-up of a new wastewater treatment plant, the Water Reclamation Division (WRD) of the CCWA had a requirement to monitor the industrial flow of six county pre-treatment accounts, including Clorox, Sherwin-Williams, Rexam Can Company and three smaller industrial firms.  The objective of the project was to determine if any of the industries were discharging potentially harmful slugs or toxic materials that could harm the plant.  Site selection was based on historical data from each site.  Jim Poff, Water Reclamation Manager, states 'The WRD is going to nutrient removal at all of their wastewater treatment plants which makes the plants more susceptible to toxins and slugs.ä  In addition to monitoring the flow at each site, the flowmeters would also trigger an automatic sampler that would provide a liquid sample at pre-selected flow levels for later laboratory analysis.  The sample could positively determine the precise location of the industrial flow that might have the potential to cause future problems at the plant.

The flowmeters initially purchased for the project needed to be replaced due to escalating maintenance costs.  The meters utilized a submerged flow sensor that continuously fouled in these tough industrial applications and according to Poff was a 'maintenance nightmare.ä  Costs associated with confined space entry, maintenance and lost data were escalating.

Early in 2002, a search for six replacement flowmeters for this application began. Poff was put in touch with Marsh-McBirneyâs (MMI) local representative, Pete Pillar of Herdco, via the countyâs Wastewater Collection Systems Division.  The Collection Systems Division were long-time users of MMIâs Flo-Tote Open Channel Flowmeters.  Pillar discussed with Poff the advantages of MMIâs new Flo-Dar Radar Velocity/Area Open Channel Flowmeter and how it could be the solution he was seeking.

The Flo-Dar Flowmeter measures open channel flow remotely without the need for a submerged sensor.  The 'above the flowä installation eliminates maintenance and lost data due to sensor fouling.  Flo-Darâs easy installation requires no manhole entry and the sensor can be installed and/or removed from street level.  With Flo-Dar, costs associated with confined space entry manpower and equipment can be eliminated forever.

Flo-Dar 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.

After learning more about the Flo-Dar meter, Poff felt confident that it was the opportune solution for the WRDâs industrial flow monitoring projects. He stated, 'The number one reason we went for Flo-Dar was that there is nothing in the flow, no probe or anything that can be fouled by the types of applications we are measuring.  The other reason is the fact that you can remove it very easily with the retrieval pole by turning a lever·you donât have to do confined space entry to remove the meter. ä

Six Flo-Dar Model 464âs were ordered and installation was completed in November 2002.  The Model 464 is a permanent DC-powered version of the Flo-Dar flowmeter that has four standard 4-20 mA outputs.  Currently, one of the flowmeters is connected to a telemetry system with plans to phase the remaining five into the system in the near future.  The flow data from the telemetered Flo-Dar is transmitted back to the Environmental Services Manager who is responsible for the countyâs industrial pre-treatment accounts.  Flow data from the remaining meters is downloaded on site and delivered back to the office by field personnel.  Flow reports and data analysis are accomplished utilizing Flo-Ware software.  Flo-Ware is the user on-site set-up, data management and report generation software for the meter.   According to Poff, 'The Flo-Ware software has been really easy to use and we like that feature.ä

In addition to providing accurate and reliable flow data, the Flo-Darâs have benefited the county by recovering new revenue for storm water discharges not seen prior to the meter installations.  Poff states 'The meters allow us to cross-check the data being reported by each industrial site.  We did not have that capability prior to the Flo-Dar installations.  The flowmeters have just been great.ä

Additional CCWA Information: CCWA has developed innovative ways of treating and disposing of waste materials and then using those materials for environmental improvement. CCWA takes all of its wastewater solids and converts them to usable products. One such product is a patented fertilizer called Agri-plus 650, which is sold by the ton and used by the agricultural industry in Florida. Another product is a soil enhancing compost that is sold in bag or bulk form to local residents and nurseries. In addition to CCWA's innovative means for converting wastewater solids they also make use of the liquid wastewater effluent. At CCWA 78% of all wastewater effluent is land applied using a vast array of sprinklers on our over 4000 acres of wooded land. The water is converted into needed nourishment for the forest plant life. It is these innovations and progress that have helped CCWA emerge as a world leader in the water and wastewater industries. http://www.ch2m.com/ccwa/ccwa/ccwa_general.asp