By Bruce Koppenhoefer
The city of Guntersville, Ala., has a population of about 7,500 in a county of more than 82,000. It sits on the southern shore of the 69,000-acre impoundment that bears its name on the Tennessee River. The lake is a fishing Mecca for bass fishermen around the Southeast and beyond, consistently listed as a top producer among the state's waterbodies, and it will be the site of the 2014 Bassmaster Classic tournament. The lake is also the city's water supply.
|One of four water tank RTUs currently in the cellular lineup. The small white "bumps" atop the RTU are the cellular antennae, eliminating traditional radio equivalents that require more difficult-to-achieve height locations.|
Guntersville's Sunset Water Treatment Plant sits right on the lake's shore, with facilities closely neighboring the water. The plant is currently undergoing expansion from a capacity of 4 MGD to 6 MGD, with ultimate capacity for 8 MGD. The development involves a second administration building, where an expanded control operations center and lab testing facility will be housed with more filters and clarifiers to serve a greater capacity. The existing building will be retained and renovated to provide more space for administrative and training functions.
In conjunction with the expansion, the city has chosen to replace five of its SCADA RTUs, four water tank units and one pump station unit, switching from land-line transmission to cellular communications. With cellular rates being a flat amount for unlimited usage, the city expects to save a considerable amount in telephone charges compared to its costs for land lines.
|The CTU polls the RTUs, obtaining the tank level data and providing it to a local PLC and HMI software. The system is fully expandable to add more RTUs, add altitude valve control, and much more.|
The replacement project was handled by Birmingham, Ala.-based Revere Control Systems, who employed its ScalableSCADA® product line. This offered Guntersville a non-proprietary technology that can easily grow as its needs grow. Further, the system included a central terminal unit (CTU) that polls, receives and processes the signals from the five new RTUs. The CTU feeds its information to an HMI display in the operations center, providing operators with immediate information updates for any status changes at any of the RTU locations. The system is fully expandable to add more RTUs, altitude valve controls and much more.
In addition to the benefits of reduced costs for telecommunications charges, the cellular approach has a side benefit: Unlike other wireless techniques (UHF, VHF, 928/952 mHz, spread spectrum, etc.) that employ radio technology, cellular transmission requires no special antennas. This eliminates the need for towers, line-of-site and height adjustments and other costs to site, place and maintain radio antennas.
|Existing filters (foreground), associated control room with clarifying tanks (left) and partially-completed expansion tanks (background). Ultimate capacity will be 8 MGD.|
As a result of the replacement, details of dollar savings have not been released, though they're estimated to be in the range of several hundred dollars per month - a substantial savings for a city of this size. In fact, the savings are significant enough that the city intends to expand the number of cellular-based RTUs in the system.
About the Author: Bruce Koppenhoefer is Director of Communications for Revere Control Systems. Bruce received his BSEE from Northwestern University and has spent the last 35 years marketing technical products and services.