The Water Research Foundation (WRF) has published a suite of deliverables to help water and wastewater utilities utilize...
Situated on the bank of the Detroit River, Trenton has been the site of heavy manufacturing for the better part of the last century. The area has produced everything from steel to automotive parts to industrial chemicals. Regardless of whether the economy sours or municipal budgets shrink, the Trenton municipal wastewater treatment plant (WWTP) must protect its community and waterways from contaminants.
In 2002, Trenton upgraded its WWTP with several layers of process protection and redundancies using Rockwell Automaton hardware and software. Five years later, Trenton—along with most cities across the country—was facing budget shortfalls. Rockwell Automation approached the Trenton plant with a way to keep maintenance costs low while adding an extra layer of protection to the city’s wastewater treatment system: a comprehensive services and support contract.
Process Control Plans
Municipal WWTPs are responsible for collecting local wastewater, purifying it and then returning it to local rivers. In Trenton, the complex process of wastewater treatment takes approximately 15 hours from the time the water enters the plant to the time it is released safely. Raw wastewater makes its way to the plant from the city’s sewage system with the help of three remote pumping stations and one remote emergency pumping station. The water passes through pretreatment, where large solids are removed. From there, it heads on to primary treatment, where remaining solids are removed by passing through a series of five large clarifier tanks. Any remaining pollutants are eliminated during the biological process. This water is chlorinated, then dechlorinated and returned to the river.
The Trenton WWTP processes an average of 4 million gal per day (mgd) of wastewater, with a design of 6.5 mgd. Even with this extra capacity, heavy rain events can cause overflows and discharges. Trenton’s wastewater treatment system is multifaceted, including many offsite components. The process is susceptible to unpredictable weather conditions, and errors can have a direct and harmful impact on the health of the receiving stream. Making the process more manageable is the job of Pat Raftery, Trenton’s WWTP superintendent.
WWTP superintendents face a similar issue in every city: Their process control systems are generally composed of an assortment of equipment platforms from a variety of vendors. Like most government-run operations, WWTPs are required to accept the lowest bid for any project. This means that the most affordable combination of process automation hardware and software wins, making it difficult for the plant superintendents to plan upfront investments for long-term benefits and cost savings. When Raftery oversaw the Trenton plantwide upgrade in 2002, he planned for a standardized process control system from the beginning.
“I wanted only the most reliable equipment,” he said. “The industrial byproduct in the wastewater we treat can be really hard on electrical components. When we were looking to overhaul the plant, we wrote our specifications so anyone submitting a proposal to carry out the upgrade could only use Rockwell Automation controllers and software.”
Trenton upgraded its main process control system to include redundant Allen-Bradley ControlLogix programmable automation controllers. The FactoryTalk AssetCentre change management software is used to ensure compliance with the Michigan Department of Natural Resources and Environment requirements for disaster recovery. The plant’s power distribution system utilizes Allen Bradley IntelliCENTER Motor Control Center software with Powermonitor meters. Additionally, the plant’s SCADA system is monitored by redundant servers running FactoryTalk View SE human-machine interface software and uses wireless EtherNet/IP to monitor four remote pumping stations that run on Allen Bradley PowerFlex drives.
With the upgrade, Raftery and his employees can monitor and control the plant with ease. “If someone calls me with an issue at the plant at 5 a.m., I can log in remotely and troubleshoot the problem immediately,” Raftery said. He also is able to run reports quickly to see how the plant functions over a certain time period. Raftery and his crew continue to be pleased with the performance of their new hardware and software. The standardized system allows Raftery to run the plant with 11 operators and one electrical technician.
Trenton’s automation system helps reduce costs and increase safety, but running a high-tech process plant requires high-tech support. When Rockwell Automation came to Raftery with the proposal of a services and support contract, he recognized an opportunity to keep operating expenses low and help provide the plant with continuous access to experienced resources.
With its services contract, the plant receives monthly onsite visits from a preferred technician. The contract also includes software upgrades, a fixed rate for emergency service and the company’s TechConnect support. The TechConnect support provides unlimited, real-time access (over the phone or online) to the Rockwell Automation global network of customer support and technical resources from 8 a.m. to 5 p.m. daily.
Since the Trenton plant standardized on Rockwell Automation equipment during its 2002 upgrade, the company’s services and support have covered the automation needs of the entire wastewater treatment system.
The monthly technician visits have had a direct impact on Trenton’s wastewater treatment operations. Plant operators simply create a checklist of issues for the technician to address while on site. Employees now have a source to turn to for the myriad of questions that come up each month and have more confidence knowing there is a place to go for answers. Workflow is more efficient, and small nuisance issues are fixed before they become larger problems.
The technician also trains plant employees on an ongoing basis. Operators now can stay up to date on new developments and immediately are able to leverage software upgrades. Furthermore, Trenton can use all of these services for the entire plant. Before the plant standardized on products and retained a services contract, many different service providers were called in when issues arose to take care of different pieces of hardware and software. Unfortunately, this often meant that one service provider would blame issues on another company’s product. Now that one organization provides services for the entire plant, there is no finger-pointing. Whatever automation problems arise, there is an experienced company technician on call with a solution.
As a result of the service contract, Raftery also has the option of pulling in a specific area specialist when necessary. When the plant experienced a problem with one of its drives, Raftery was able to request that a specific drive technician make the monthly visit instead of the regular technician.
“It is incredibly valuable to our day-to-day operations to have regular visits from the Rockwell Automation technician who is familiar with us and our plant. We’ve also needed support from the on-call area specialists. When it comes to support, our plant requires both options and layers,” Raftery said. In an emergency, this support becomes the plant’s lifeline.
Not long after the plant contracted services from Rockwell Automation, it experienced a main server meltdown. Raftery and his team were operating blindly. They could not monitor what was happening at offsite pumping stations or control any plant functions remotely. To make matters worse, the plant’s sole electrical technician was on vacation and out of the state.
Raftery contacted Rockwell Automation, and within five hours, the problem was fixed. The service technician arrived at the plant and transferred plant operation to the redundant system. He was able to bring remote monitoring and control functions back online, thus ending the risk of an overflow or process failure.
“We’re spoiled with the automation system we have now,” Raftery said. “When the server meltdown happened, it was immediately apparent how dependent we’d become on our high-tech monitoring, diagnostic and control capabilities. The new service contract means we don’t have to worry about operation failures from technical issues. I can allow my employees to take vacations with peace of mind. I know the plant will be fine.”
The citizens of Trenton, too, can rest easy. Specialists are providing comprehensive services to support their municipal wastewater treatment operations. Local rivers, the environment and the populace are protected. Furthermore, the added protection from Rockwell Automation Services and Support helps keep the cost of wastewater treatment low for the city’s taxpayers.