DCS Streamlines Monitoring, Costs and Training at Wastewater Plant

March 11, 2019
After Lima, Ohio, migrated its wastewater plant to a distributed control system, the city increased its water capacity, met updated regulations, improved training and reduced costs with real-time monitoring capabilities.

In so many industries, the workforce is undergoing structural changes, prompting workers to expand their roles into areas in which they may not have had any previous experience, such as industrial networking, maintenance and remote monitoring. Some of the factors driving this shift include ongoing plant upgrades, emerging regulations and, of course, the adoption of new automation technologies that change processes for many workers.

An example of this trend can be seen in the recent modernization efforts at the wastewater facility that manages treatment demands for the City of Lima, Ohio. The plant—initially built in 1930—recently upgraded its control system to increase water treatment capacity from 53 million to 70 million gallons a day (MGD) with Rockwell Automation’s PlantPAx distributed control system (DCS).

“We were using equipment from the early 1990s and control systems that were nearly 30 years old,” says Matt Fiedler, a process control specialist for the city of Lima’s wastewater treatment plant. “We needed a full control system upgrade with better data insights and reporting capabilities to help us increase capacity, ease maintenance and meet the EPA requirements.”

In 2014, the U.S. Environmental Protection Agency (EPA) instituted more stringent guidance around overflows into natural water sources, which challenged Lima’s wastewater plant to change how it was operating. Before the new regulation, the treatment plant was permitted multiple overflows per month. This changed to a limit of five per year after implementation of the new discharge rule.

In addition to complying with the EPA, the plant’s maintenance staff also wanted to improve efficiency and install a remote monitoring system that would help future-proof the plant. With no remote access capabilities, all troubleshooting and maintenance had to be performed on-site, according to the municipality.

If there were overflows in the river, for example, the absence of remote maintenance for combined sewer overflows required additional plant staff to be on-site to monitor them and gather samples. The lack of control access to the underground gate structures and lift stations caused additional problems because operators couldn’t restrict flow to the plant, causing further overflows during rain events. Lima’s wastewater district includes 32 lift stations, three underground gate structures, five combined sewer overflows and five radio repeaters.

Improving the flow

Working with Novi, Mich.-based system integrator Commerce Controls (CCI), a solution partner in the Rockwell Automation PartnerNetwork, the City of Lima implemented the PlantPAx distributed control system (DCS) from Rockwell Automation as a single plantwide system for all processes and operations at its water treatment facility. The PlantPAx system leverages EtherNet/IP and open communication standards to streamline control and information data flows. The modernization initiative also introduced new Allen-Bradley Stratix 5400 and 5700 industrial managed switches for better data collection and network monitoring, along with an updated Stratus Server running Veeam with eight virtual machines.

Rockwell’s PlantPAx DCS uses a standardized design, pre-defined code and faceplates with an intuitive interface, eliminating the need for custom coding and easing the onboarding and training of new operators.

Before the updates, common human-machine interface (HMI) operator metrics were a challenge due to specialized coding and the lack of a comprehensive control platform. “In the past, extracting historian data was a nightmare and, once extracted, it needed to be reformatted to make it usable by the administration,” Fiedler says.

The system now provides automated reporting and direct visualization of historical and real-time process trends, such as overflow counts, pumping metrics and dissolved oxygen numbers. With the upgrades in place, the plant uses FactoryTalk Historian software to collect and archive process data on all equipment and instrumentation. “We didn’t have an actual working historian previously, so it's been nice to have all this data at our fingertips,” Fiedler adds.

Importantly, the new DCS also introduced remote access capabilities for system troubleshooting and maintenance, saving plant workers hours of travel time each month and minimizing system downtime.

In conjunction with these updates, the city also added new Allen-Bradley CompactLogix controllers to the 32 lift stations and eight more at the plant level with CCI’s help.

The modernization effort is providing new opportunities and challenges for the workforce. “I was pretty new to PLC programming when I started in 2013,” Fiedler says. “But [the] many training sessions at RSTechED and working side-by-side with CCI have been beneficial.”

For the plant, the modernization initiative reached the 53-70 MGD goal, minimized river discharges and provided a foundation for further plant developments.