AWWA ACE68744

The Scott Candler Water Treatment Plant (SCWTP) began full-scale production on July25, 2007. SCWTP has an advanced supervisory control and data acquisition (SCADA) system that monitors feedback frominstruments, valves, and equipment from all of the numerous processes used to meet thedesign capacity of 150 mgd. In addition to the traditionalprocess performance parameters now routinely monitored by modern plant SCADAsystems such as turbidity, chlorine residual, pH, filter flow, and headloss, the majority ofcomponents for all treatment processes are continuously monitored by the SCWTPSCADA system. Examples of additional components monitored include chemical flows,chemical tank levels and temperatures, theoretical pump performance, powerconsumption for specific processes, and multiple additional process parametersassociated with the ozone system.The SCADA system at SCWTP is comprised of several different network platformsincluding Ethernet, Profibus, ControlNet, and DeviceNet. To accommodate the largeamount of data that is required to move throughout the system, the control systemdesign segregated the data by creating different networks within the SCADA system tocarry the information. Fiber optic technology was used to provide increased throughputand increase the speed on the different networks. There are more than 40,000 tags in thehuman machine interface (HMI) system alone, which is comprised of redundant serversand more than 16 clients. The main control of the water treatment plant is beingaccomplished by the latest in programmable logic controller (PLC) hardware technology.Several PLC processors share a common Ethernet backbone, while the HMI systempasses data on another network separate from the PLC's, saving bandwidth and isolatingdata streams. Several critical PLCs are backed up using a redundant processorconfiguration, making this a cost effective and robust system.The data on the HMI servers can be visually trended to allow the operators andmaintenance staff the ability to observe process operation in real time. The ability tocreate historical trends has been instrumental in solving a variety of unusual occurrencesduring plant start-up operations, including mystery overflows into chemical containmentareas; identification of triggers causing ozone system shut downs; and, determination ofthe causes of anomalies in what would be considered normal operations of filters,chemical systems, and ancillary ozone system processes. This advanced SCADA systemwas specifically designed to enhance the operability and optimization of the SCWTP andillustrates the power of the instrumentation and data collection tools that have onlyrecently begun to be used in the water treatment industry. This paper presents examples of the methodology used by operations and maintenanceat the southeastern United States' largest and most advanced surface water treatmentplant, to utilize the capabilities of their advanced SCADA system and help save time,money, and headaches. Includes figure.

Product Details

Edition:

Vol. - No.

Published:

11/01/2008

Number of Pages:

9

File Size:

1 file , 1000 KB