Flushing Out the Old
Whether storm sewer runoff or drainage from home or business use, once water leaves the drain, it enters a complex network of underground pipes. And once processed at a wastewater facility, that water typically completes its journey by emptying into a lake or river.
Efficient water/wastewater treatment facilities are essential to keep surrounding rivers and lakes safe and clean of chemicals and other disease-causing pathogens often residing in municipal wastewater.
Lima, Ohio, releases its treated wastewater into the Ottawa River. Constructed in 1930, the city wastewater treatment plant services more than 40,000 people within city limits and surrounding communities. Since conception, the city has evolved and so has its needs including processes for screening and grit removal, sludge digestion and more.
Overflows and Overtime
In 2014, the Federal Environmental Protection Agency (EPA) changed guidance around overflows into natural water sources.
The change meant Lima needed to limit river overflows to five times per year, instead of the former multiple times a month, depending on rain events. Exceeding that allotment would cost the city steep fines. To sustain five discharges per year, it was necessary to increase the treatment plant’s water capacity from about 53 to 70 million gallons per day (MGD). Since capacity increase was required, the city decided a complete, plant-wide upgrade was necessary, as well.
Lima’s wastewater treatment plant was running on an outdated control system. “We were using equipment from the early 90s, systems that were nearly 30 years old,” explained Matt Fiedler, process control specialist for the City of Lima wastewater treatment plant. “We needed a full system upgrade with better data insights and reporting capabilities to help us increase capacity, ease maintenance and meet the EPA requirements.”
Another complication: the aging system had been customized, and system knowledge left with a former employee once he retired. The lack of standardization was a stumbling block for training new employees. And the lack of in-house expertise led to frequent maintenance calls and costly downtime.
With no remote access capabilities, all troubleshooting and maintenance had to be performed on site. This meant many overnight calls for Fiedler and staff, who had to travel up to an hour roundtrip to make an adjustment that would only take five minutes. The absence of remote maintenance also complicated the process of combined sewer overflows (CSOs). For example, if there were overflows in the river, extra plant staff would have to be onsite to monitor them and gather samples. Additionally, having no control access to the underground gate structures and lift stations caused additional problems, as operators couldn’t restrict flow to the plant, causing overflows during rain events.
Opening the Flood Gates
To streamline the treatment process and data sharing across the plant, the City of Lima worked with Commerce Controls, Inc., a Solution Partner in the Rockwell Automation PartnerNetwork, to migrate to a PlantPAx distributed control system (DCS) from Rockwell Automation.
The modern DCS provides a single, plantwide solution to increase productivity of all processes and operations at the facility. And leveraging EtherNet/IP, the PlantPAx system is based on open communication standards to streamline control and information flow across the plant. The network upgrade also included new Stratix 5400 and 5700 industrial managed switches for better data collection and network monitoring. The switches help monitor panel temperatures across the various buildings and provide a quick view into the health of the network.
The new DCS uses a standardized design, pre-defined code and faceplates with an intuitive interface, providing the same look and feel across the entire plant and various processes. This eliminated the custom coding of the old system, allowing quicker programming and easier scalability for future expansions. It also eased onboarding and training of new operators.
Integrated historian and production intelligence software provides operators a window into system performance data. The historian collects and archives years of valuable process data on all equipment and instrumentation. The system now provides automated reporting and direct visualization of historical and real-time process trends, such as overflow counts, pumping metrics, dissolved oxygen numbers and more. “In the past, extracting historian data was a nightmare. And once extracted, it needed to be reformatted to make it usable by administration," said Fiedler.
The new DCS also has remote access capabilities for system troubleshooting and maintenance. “Commerce Controls can now remote into the system and address issues offsite, saving hours of travel time each month and minimizing system downtime,” said Fiedler.
In addition, the city implemented Stratus servers to help maintain uptime and production. The servers added a new level of redundancy to make sure the facility stays up and running during any unplanned event.
The PlantPAx DCS has impacted Lima in many positive ways: making the control system consistent plant-wide, easing training, simplifying maintenance through remote capabilities, improving overall plant performance and assisting in EPA approval.
Having a standardized solution has simplified coding across facility systems. “The PlantPAx DCS helped us solve inconsistencies in our processes and streamline control, offering operators a better understanding and similar look and feel across plant facilities for a consistent and more streamlined training process,” explained Fiedler.
The plant has also realized significant decreases in downtime since the system upgrade. The city saved approximately 50 hours of overtime with an average cost savings of $2,000 in the first three months of operation. “Troubleshooting is much improved with our remote access capabilities. I no longer need to travel between home and the plant after working hours due to faulting PLCs or radio failures,” said Fiedler.
The production intelligence software improved performance management and process optimization. The software provides the city with pumping metrics and allows plant operators to set up templates that can calculate overflows. And historian software provides historical trending in real-time, whereas the plant previously only had trend analysis once per day.
“The PlantPAx DCS helped meet all of our goals and more,” said Fiedler. “We not only met our production increase from 53 to 70 MGD and minimized river discharges but also gained important data visibility and eased flexibility for future plant expansions. This is our new control standard across the city and look forward to implementing into every new water/wastewater project in the future.”
The results mentioned above are specific to the City of Lima’s use of Rockwell Automation products and services in conjunction with other products. Specific results may vary for other customers.
PlantPAx and PartnerNetwork are trademarks of Rockwell Automation Inc.
EtherNet/IP is a trademark of ODVA.