Optimizing Operations

The benefits of SCADA control systems

The Central Arizona Project's Picacho Pumping Plant

Just about every water utility uses some type of Supervisory Control and Data Acquisition (SCADA) system. SCADA control systems incorporate computers, networked data communication, and graphical user interfaces to manage systems and control industrial processes at remote locations. This high-level supervisory management system also incorporates other devices, including programmable logic controllers and Proportional Integral Derivative controllers to directly interact with sensors, valves, pumps, motors, and other equipment. Real-time controller calculations are performed by networked modules that connect with field sensors and actuators, allowing remote monitoring and issuance of commands by operators.

SCADA systems are similar to distributed control systems that incorporate multiple means of interfacing with the main office. They can control processes on multiple sites over long distances via remote access of local control modules. SCADA systems also collect and record data, monitor systems, process real-time data, and send control commands.

Aqua America, a water and wastewater utility company serving three million customers in Pennsylvania, Ohio, North Carolina, Illinois, Texas, New Jersey, Indiana, and Virginia, began using SCADA in the mid-1970s. “We started with IBM System 7,” says Jim Barbato, director of corporate engineering, who quickly points out that he wasn’t with the company at the time. Since then, the company has gone through numerous evolutions and, because it operates in several states, works on platforms it inherited when it took over local utilities.

One of the changes over the years is the shift from focusing on the importance of control to data acquisition. Jim McGinley, manager of control center operations at Aqua America, PA, blames past dismissal of the importance of data acquisition on size restrictions that once permitted only a limited amount of data to be stored.

Today, Aqua America collects a lot of data, which is stored on a remote server. They do not use cloud storage. “The more information we get, the better,” says Curt Steffy, vice president of production at Aqua America. Aqua America’s internal staff does the programming, and they design for more information than is needed because, as Steffy says, “there’s never too much information. It lets us know where we can improve because we can see what’s going on in the system. All systems are managed by Aqua America. We are the utility; we are the public water provider. We run and use it day-to-day.”

SCADA also helps with regulatory reporting. Steffy indicates that the requirements have increased, demanding a reading every 15 minutes. It’s too onerous of an obligation for personnel to accomplish, but is easily performed by SCADA. “As the regulations change, data acquisition becomes even more important. SCADA collects data for regulatory purposes and for historical record. It’s very helpful because it does what it’s intended to do: collect data and offer control.”

Control begins with notification. Barbato explains that a dispatcher monitors the online instrumentation, watching for trends and early warnings. “In an emergency, we can shut down remotely instead of sending people.”

“It keeps the customers happy knowing that we’re watching and will alert them to issues,” says McGinley.

In addition to collecting data, SCADA can perform some tasks remotely, saving manpower. For example, Barbato says, when the weather gets hot, the water level in the tanks drops and wells come on automatically; the system starts to refill the tanks remotely without the need for human intervention. “The entire project came out of regulations,” he reveals. “Instead of adding people, we chose SCADA.”

Despite the advanced automation, staff is still necessary. McGinley says it’s important for the utility to make sure training is up to date, especially if the utility routinely upgrades its system. Training is one of Aqua America’s biggest challenges. “You need the operator to understand what they’re doing. They should use critical thinking and have a knowledge base.”

Large amounts of data can appear overwhelming unless the data is properly organized, processed, evaluated, and stored for future reference. Properly processed and understood data is vital to the successful operation of a water system.

Because data is crucial, SCADA is essential to water system operation, monitoring, maintenance, and troubleshooting, as well as security monitoring. The system used by Albuquerque Bernalillo County Water Utility Authority is comprised of nearly 60 production wells (up to 175 mgd capacity), one surface water treatment plant (up to 86 mgd capacity), nearly 50 pump stations, almost 70 water storage reservoirs, numerous smart PRVs, smart flow control valves, and smart distribution pressure monitoring. All are operated and monitored via a SCADA system.

“We use a radio telemetry-based SCADA system with FCC-licensed dedicated frequency,” says German Andrade, chief engineer in the groundwater and plant operations division. SCADA allows virtually “hands-free” operation as long as systems, equipment, and monitoring instrumentation are not in alarm. It also allows operations management staff to optimize workforce utilization by allowing them to focus on problem areas (i.e., sites with alarms) and to narrow down operational problems by trending past performance (stored in SCADA historical database) versus a current situation. “Without a sophisticated and comprehensive SCADA system, the Water Authority would need a much larger workforce present in the field at all times.”

SCADA collects data automatically, eliminating the need to hire and train a large workforce to gather information. “Our specialized SCADA staff monitors data quality and repairs problems to ensure a consistent high-quality data feed,” elaborates Andrade.

Analytics are performed regularly via SCADA-built routines to evaluate data both graphically and with data tables. Certain large amounts of SCADA data (such as critical water quality parameters for surface and groundwater) are further processed in a Hach Wims software platform to issue specialized reports that use a large number of data fields to summarize specific aspects of water production and water quality.

The impact on the system is profound, Andrade says, because the water quality and quantity produced must always be compliant with all applicable rules and water quality regulations. “The effort to collect and analyze water system SCADA data is relatively small compared with the responsibility to always produce high-quality compliant water. The data collection and associated analytics effort are minor when operational or water quality issues arise that require in-depth analysis to demonstrate proper operation, prove consistent compliance with regulatory requirements, and overcome equipment malfunctions.”

Water quality and water quantity can sometimes be a trade-off, but SCADA helps San Antonio Water System (SAWS) on both counts. The water utility stores water in an aquifer south of San Antonio; in dry years when the primary supply is low, they use stored water. Steve Clouse, COO, says they’ve managed to save 120,000 acre-feet of water stores, which is roughly half a year’s worth of water. They expected only 35 to 40 acre-feet, so he is pleasantly surprised.

SCADA allows them to move the water around the city to serve their customers. “We’re developing new sources, but we must keep water available. SCADA gives us flexibility in how we run the system.”

SAWS, which has been at the forefront of SCADA systems since the utility first began using it in the mid-1960s, covers a large service area of approximately 900 square miles. That area is expanding as the community moves farther out. With 80 pumping stations and 135 wells, Clouse considers SCADA an essential tool to operate efficiently.

All utilities have some form of remote telemetry units, but the smaller the utility, the more likely they are to operate manually. “We would need lots more manpower without it! We have to have a system like SCADA in place. It’s essential for growth; without it we would have to speculate because we’d have no data.”

CAP canal in Mesa, AZ

With SCADA, they have data—in fact, “overwhelming data,” in Clouse’s words. “There are still parts of SCADA we don’t use. You can’t use it all. Know what’s important to you.” And yet, every time they get good data and information, it turns into a request for more.

Real-time information allows them to analyze details of where the water is going. They know pressure, flow trends, starts and stops, changing systems such as requests from the fire department, and historical use for changing demands. “We know the ranges of the system and where the demands are,” adds Clouse. “We can see problems before they’re reported.”

Operators sit next to the emergency response. If a major pipe breaks, they know immediately and can bring on the well and the pump system quickly so that customer service is not interrupted. Clouse says there’s a “strong conservative mentality” in San Antonio, but sometimes the utility still has to dictate when customers can water their lawns during a drought. “We try to reduce pumping during a drought due to endangered species in the area.”

With SCADA, they can also link to GIS or other databases for a comprehensive view. SCADA compiles data and converts it to graphical data to help make decisions. SCADA helps them predict issues and determine the condition of sewer and water mains without shutting down the water supply. “Old is not necessarily bad; we replace what needs to be replaced,” notes Clouse.

Over the past several decades, SAWS has experienced several evolutionary upgrades. “Our current system has outgrown the original system,” acknowledges Clouse. When SAWS acquired a separate water system using a rudimentary system, they began the process of upgrading that system to a single, more robust platform that will be good for 20 years.

Clouse predicts that SCADA will continue to grow over the next two to three generations, with more demand and more data requests. That’s fine with him. “We make better decisions, thanks to SCADA . . . although we can always do a better job,” he adds.

You should always collect more data than you need, just in case, believes Patrick Dent, water operations manager and civil engineer for the Central Arizona Project (CAP). CAP is a water supply project with 15 pumping plants and an open-channel canal with 335 miles of aqueduct from the Colorado River through Phoenix to Tucson. “We are a wholesale water provider for the City of Phoenix, the City of Tempe, farmers, Indian tribes, and others,” he explains.

Uphill from the river at Lake Havasu, the water has to be pumped. “It gets lifted, then we use gravity flow through the canal, then it’s lifted again and flow again . . . ” To get water to the customers, there is a turnout on the canal—a pipe with a regulator. Each turnout has a meter that is part of the SCADA system.

“All the control features are on SCADA,” says Dent. “It operates the pumps to start and stop on a schedule.” In addition, it moves the big gates on the canal remotely, sending a signal for them to move and tracking their movement. There are gates controlling the flow every 7 miles along the canal. They can be opened to 16 and 1/2 feet or closed.

CAP also uses SCADA to control the aqueduct. “We have 12 people and no field staff,” reveals Dent. “We’ve never manually done it; the spatial expanse is significant. It would take an army—at least 80 to 100 people—to cover it manually. We need the system; we rely on it.”

CAP is a Bureau of Reclamation project. Dent calls it “just a young child”—authorized in 1968, constructed in the mid-1970s, and largely completed in the mid-1990s. Because of the lateness of the project, he says, a centralized control system was part of the design.

The SCADA system works like a master station, with a centralized computer in Phoenix that talks to field devices such as the remote terminal unit, now called a programmable logic controller (PLU). The PLU communicates with sensors and other devices, routing information to computers with SCADA software. The SCADA software processes, distributes, and displays the data in order for operators to analyze it as part of their decision-making process.

Dent says they replaced the master station in the mid-90s and the field devices in the mid-2000s. They should last 20 to 25 years, he says, although he advocates a refresh every decade. Technology changes rapidly, but more slowly in industrial control than in IT. Their last refresh was 2012.

It’s a custom application with open architecture, so it’s easy to expand to add new equipment or to match the equipment you’re trying to control. Dent says they wanted a more generic version due to limited parts availability.

They collect 22,000 data points. Specifically, they collect two kinds of data: analog (4,000 to 5,000 data points) in which the instrument provides variable changing information like flow meter; and status (15,000 to 16,000 data points) that record a change of state (on or off, open or closed). They also maintain a historical database, selecting specific categories to save for future reference.

CAP uses the data to monitor flows, water, and levels. They also use it for customer billing: revenue. “We use it for operational-type investigations,” adds Dent. “The engineers on staff have access and can investigate issues.” There are three dispatchers on the day shift. If they see an alarm, gate, or pump not operating, they respond by calling maintenance to address the mechanical or electrical issue in the field.

SCADA is reliable, Dent says, with 99.9% uptime and many redundancies. In addition to helping improve efficiency, it reduces costs because of its reliability and its ability to share maintenance records.

There is also a day-ahead scheduler so customers can order 24 hours in advance. “We create a schedule for the time and power required, the amount of water, and when to start and stop the pumps,” explains Dent.

Because CAP is a junior priority user, subordinate to California users, Dent says SCADA is an invaluable tool to help them manage water. With warmer, drier conditions in the Rockies reducing the snowpack, they have to be on top of water usage. “We work hard on our water resources,” he insists. Those include in-state surface water, groundwater, and the CAP project. By adequately managing their water resources, he projects that Central Arizona has room for population growth in the water supply.

The term “SCADA” was first used in the early 1970s when PLCs and microprocessors increased the ability to monitor and control automated processes. Networks were not available in those days; each SCADA system was independent.

Smaller computer systems, Local Area Networking technology, and PC-based HMI software helped SCADA systems connect to other systems in the 1980s–90s. A major change came in
the early 2000s when SCADA adopted an open system architecture and communication protocols that were not vendor-specific.

The technology boom coincided with personal computing to accelerate adoption and development of SCADA systems, which have become vital to many businesses and operations because they help maintain efficiency, alert operators about issues and thus reduce downtime, and enable operators to make smart decisions about how to improve their processes, reduce costs, and increase efficiency, based on real-time data input.

SCADA systems can be large or small, simple configurations or complicated installations. Many industries, such as oil and gas, water, energy, and manufacturing now rely on them to control operations, collect data, communicate issues, and maintain efficiency. WE_bug_web


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