Credit: Photo: Lynn Light, water plant supervisor, City of Pigeon Forge, Tenn.
Above: Allen-Bradley drives were chosen for installation in the Pigeon Forge water treatment plant motor control center. Photo: Rockwell Automation Right: This computer screen, part of a newly installed automation system at the Pigeon Forge water treatment plant, provides an interface for personnel to set operation and alarm parameters.
Screen views like the one pictured offer graphical interfaces with operators making operational monitoring and control easier to learn and more efficient to implement. Photo: Rockwell Automation
HMI software with RSView Active Display System, also provided by Allen-Bradley, is installed throughout the facility to allow operators to monitor all aspects of the process. Operators can view basin levels, filter operations, chemical application, flow rates, water turbidity, and chlorine content. Plant workers can run many operations remotely through this system, including controlling the four remote water pumps at Douglas Lake, based on the basin levels at the plant.
Even though plant capacity was increased, remote monitoring and control eliminated the need for extra personnel at Pigeon Forge. For example, filter operations at the basin, including scraping floc from basins into the trough and transferring it to the wastewater plant, can now be monitored on site at the filter station via four HMIs or remotely via the RSView system. Personnel can even remotely add the flash mix.
“RSView clearly displays the entire treatment process,” said Joel Skelley, electrical engineer with SSR. “RSView libraries and pre-built parts help us create intuitive screens that follow the flow of the system. This allows plant personnel to move smoothly from one screen to the next and see water flow rates for more efficient system monitoring and control.”
In the previous system, an operator would spend about 30 minutes walking through the plant, manually checking gauges and pumps. With the new integrated system, operators now spend only minutes monitoring computer screens to get the same operational information. As a result, operators are able to solve problems 30% faster.
Also, data files now are sent directly to the plant's server where they are archived for a year. After a year, the data files are saved to compact discs and stored offline. The stored data can be used for faster troubleshooting and maintenance. When an alert flashes on the screen, plant engineers can quickly reference the stored data to determine when the problem started and how it should be resolved. As EPA data collection requirements evolve, the water plant will be able to comply by modifying its collection parameters.
To minimize construction time, Rockwell Automation engineers assembled and factory tested the motor control center before shipping it to the site—a common step often used by automation companies to reduce installation time and troubleshoot potential problems. This type of factory production assembly and test makes onsite wiring and startup much easier and eliminates many of the common factory-to-field installation problems typically associated with this type of installation. Overall, this procedure reduced the time to engineer the system by 15% and the installation and startup time by 25%. Once the system was installed, SSR provided startup and onsite operator training.
“Training on the new system was easy,” said Lynn Light, chief water plant operator at Pigeon Forge. “The graphics walk our personnel through the process, improving comprehension and reducing training time.”
In addition to the controls at the Douglas Lake pump house, the city also integrated a contact-switch-based security system to alert the district of unauthorized entry. By integrating the intrusion detection system into the remote supervisory control and data acquisition system, the district is now better prepared to minimize site- security vulnerability at these remote sites.
If the city of Pigeon Forge had expanded their production capacity using the same systems, they would have needed more than double the personnel they were using at the time. With the automated system in place, the water plant has successfully tripled its capacity to 12 mgd without adding plant personnel, saving an estimated $200,000 per year. With higher capacity, the city now meets projected city water demands, which continue to grow 10% annually. The added production capabilities also generate revenue for the city. Now with the ability to triple its capacity, Pigeon Forge can sell water to neighboring towns. Gatlinburg, a neighboring tourist attraction, currently purchases more than 90 million gallons of water each year from Pigeon Forge.
Since the newly expanded plant opened—ahead of schedule and under budget—all systems have operated without failure. The operational costs of the facility have been reduced by $20,000 annually, translating into a 28% operational cost reduction. The new plant also uses fewer chemicals, less water, and less energy thanks to the new filter system that allows longer filter runtimes between backwash cycles.
“We know more about what is going on at a much more detailed level than before,” said Light. “The integrated control systems and intelligent motor control centers alert our engineers of problems long before we could have humanly detected them. That helps us maintain uptime and protect assets.”
— Martinez is senior marketing engineer with Rockwell Automation, Milwaukee.