The Mishawaka (Ind.) Utilities Water Division’s two-phase expansion included two new water treatment facilities and underground wells as well as a new automated control and reporting system.
Bruno Trimboli, assistant manager of Mishawaka (Ind.) Utilities Water Division, doesn’t mind being taken for granted when it comes to supplying drinking water to northeastern Indiana. He says people expect good tasting, pure and dependable potable water from Mishawaka’s underground wells.
Serving more than 40,000 people through 16,000 utility connections, customer satisfaction is high. A recent survey reported that 94% of the utility’s water customers are pleased with the service over the past six months.
Trimboli says the water system scores such high marks because of constant attention to reliability and water quality. As an example, he points to the latest and most technologically advanced improvement to the water system that was put in place in October 2003.
City engineers, led by James E. Crook, Mishawaka water division manager, agreed in 1997 that the demand for water would one day exceed supply. A two-phase expansion of the system was planned. Engineered by Malcolm Pirnie, Inc., the expansion would include two new treatment facilities and underground wells. It would also improve the dependability of the entire system with a new automated control and reporting system from Siemens Energy & Automation.
“We needed to develop additional capacity,” Trimboli said. “At the same time we decided to upgrade the SCADA controlling the entire system. The old SCADA system was PC-based and all system controls resided in an old master computer. If the master ceased to function we lost control at all of our 30 remote sites.”
Complicating the question was the SCADA controlling the potable water system also monitored Mishawaka’s wastewater plants. “We also had to separate the city’s wastewater and drinking water operations that had been managed using the same SCADA system,” Trimboli said. “It was like two people trying to drive the same car. For example, if a storm passed through the area, only one of us could acknowledge an alarm.”
Telemetry control
The answer was a scalable control system from Siemens that automatically monitors and controls each remote site connected through a wide area network. The heart of the operation is a series of SINAUT telemetry interface modules (TIMs) designed to automatically store information and communicate via 900 MHz radio. The TIMs can also communicate by phone line, buried twisted cable or microwave transmission.
According to Trimboli, the expansion upgraded the existing Virgil Street treatment plant, added monitoring capability at the Jefferson Street main office, and added a new treatment plant and underground wells on Division Street that became operational in October 2003.
The opening of the Virgil Street Plant, or second phase, is nearing completion. In all, the system will include the primary treatment locations and 35 remote sites including the wells, elevated storage tanks, booster pump stations and pressure vaults. Rather than use the conventional treatment approach of aeration and detention to filter the water, Malcolm Pirnie introduced an economical and innovative chemical oxidation system. At each plant, sodium hypochlorite is added to raw water to oxidize iron and manganese, forming particles virtually instantaneously that are readily removed by filtration.
Today, 32 of the remote sites and two of the treatment plants are operational. Each site is controlled by a Siemens’ SIMATIC S7300 programmable controller that communicates to the SCADA via a SINAUT TIM. Each TIM communicates via radio to a master TIM at each of the three master locations. Alarms and trending data may be reviewed at each master location on an HMI programmed with Siemens’ WinCC software. The HMIs at each treatment plant are connected together using MPI communication network.
Listening leads to solution
Frank Green, lead instrumentation engineer at Malcolm Pirnie, had not worked with the SINAUT equipment in the past. However, he heard of the capabilities of the system and wanted to learn more.
“Siemens came in and listened to our vision,” Green said. “We are an independent consultant and we use a variety of control systems. The city of Mishawaka wanted a state-of-the-art control system that could meet their data management and control needs, with three fully independent master telemetry locations. The multi-master time slicing capability of the SINAUT system met the need of the independent master locations better than the other systems we considered.”
Green said the decision to use radio communications from the remote sites to the master locations was based on the number of locations that needed to be controlled and monitored. The sites are spread out over a wide area and it was important that data was always available, even if one of the central computers were not working. The reestablishment of information and having all the data stored in the TIMs is a big advantage Green said.
According to Green the computers at each of the three master telemetry locations—the central offices and both water treatment plants—are fully independent and redundant. He says “anything the city can do from one they can do from the others, regardless of whether all three are on line or not. That is quite an improvement from the city’s previous telemetry system where everything went to a central location.”
The new telemetry system offers the city considerable flexibility, both to meet current needs and for future expansion.
Water quality counts
Connie Cummings is water quality supervisor at Mishawaka Utilities. She said the new automated control system has enhanced the dependability, control and maintenance of the water system.
“We had never used PLCs in our system before,” Cummings said. “The function of our SCADA system is to make sure there is potable water in the system. It makes sure the tanks are not too empty or too full, that the treatment processes are operated to good engineering practice and that the pressure in the system is maintained within desirable limits.”
Cummings said the S7300 PLCs and SCADA system are preprogrammed to run or shut off the wells depending on ground storage reservoirs and elevated tank levels. The S7300 PLCs at the plants have the capability to monitor the system and maintain production throughout the plant based on system pressure. In addition, the PLCs communicate with level sensors in the storage tanks and feed that information via the TIMs to the master plants.
“The Siemens automation system gives us much more capability than we had before because the PLCs have a certain amount of autonomy,” Cummings said. “They can run a local site and if for any reason communication is lost with the master they still have the capability to perform their function.”
Trending data helps maintenance
Cummings said the PLCs and SINAUT system have greatly enhanced the utility’s ability to gather, report and act on data as well as control the system.
“We can trend well production and outputs, finished water production at the treatment plants, chemical treatment, feed rates and chemical amounts used,” Cummings said. “This is a big improvement over the previous system and essential for reporting purposes required by state and federal regulations.”
Cummings said much of this trending information has streamlined the maintenance process.
“We have a lot more information on our pumps and motors,” Cummings said. “So it aids us in preventative maintenance and gives us the capability to schedule maintenance. We can look at pump run hours and not wait until the system breaks down. It definitely has better tracking capability than our old system.”
Trimboli said trending capability also demonstrates how the system is running. It allows them to get a visual depiction of how things have occurred over a period of time. That helps determine how to adjust different components in the system.
“We have better control over our treatment processes,” Trimboli said. “We get real-time data that we didn’t have before, including chemical feed rates.”
Today, average production at Mishawaka Utilities is about 9.4 million gallons of water from underground wells per day. Production increases greatly during hot summer months. When all three plants are operational, the system will have a 32-mgd capacity. “I don’t lose sleep on this system,” Trimboli said. “If something goes wrong, the SCADA system gets our attention. I have been impressed that the PLCs and the TIM modules associated with them are robust. My background is in engineering and I like the way it is put together and constructed. It is well built.”
