We used to think only large urban water utilities could afford sophisticated pump monitoring and controls, but we were wrong. Thanks to technology, our small Kentucky water and sewer utility can take advantage of the same reporting functions and predictive management tools.

Settled in 1818 along the east bank of the Big Sandy River's Levisa Fork in the eastern part of the state, the City of Prestonsburg is home to 3,300 people. This is coal country, but today there's no dominant industry in the area. There's a university in Pikeville, the closest town to Prestonsburg.

In 2013, we decided to upgrade our 80 lift stations. We started with the largest and most critical. Built next to the river in 1961, clogging and pump failures had maintenance crews out at the Riverside lift station almost daily.

On a dry day, the station's two 7.5 hp flooded suction pumps move 200,000 gallons; volume often doubles when it rains. Besides moving a lot of effluent, we’d set a 2-foot volume variance to trigger off/on operation to protect the river from sewage overflow.

As a result, the pumps cycled between 110 and 140 times per day. That’s an average of every 10 minutes to 15 minutes, which is two to three times most lift stations. The constant, recurring starts took a toll. Windings broke down and pump seals failed.

The pumps also shut down unexpectedly in ways that couldn't be explained by mechanical stress alone. Because spikes were most pronounced during summer and winter months, when residential power consumption peaks, we suspected there was a problem with the electrical feed into the station. We believed we were getting “dirty power” (a term for uneven distribution of power phases) from the electric utility but couldn't prove it.

Non-Clog Pumps
To help us address the lift station’s shortcomings, we turned to pump distributor Wascon Inc. in Livingston, Tenn., which serves municipalities in Kentucky and Tennessee.

Our wish list included a durable solution that could handle large sewage volumes and rain flows with enough power to operate reliably under poor and fluctuating voltage conditions. We also wanted premium-efficiency motors, predictive management software, and the ability to remotely monitor and control the units. And, of course, we wanted equipment that would need less maintenance.

‘Intelligent’ submersible pumps resolved chronic clogging at two of our 54 lift stations.

After analyzing the demands on the station, Wascon Service and Sales Representative Jonathan Cummings suggested upgrading the 52-year-old lift station with demand-based wastewater pump technology.

He proposed a pair of 7.5 hp Grundfos SL1 pumps specifically designed to handle unscreened sewage. Their tube-style impellers lack edges, dead zones, or cutting functions that can get worn and fail and, with a capacity of 408 gpm at 42.6 feet of total dynamic head (TDH), process sewage more efficiently than other impeller designs. (To see how they work, watch https://www.youtube.com/watch?v=9n7pUDTYp5U.)

Running at 1,760 revolutions per minute (RPM), the pumps pass solids up to 4 inches in diameter. We wouldn’t have to babysit the pumps in case of failure or clogging.

They were the ideal solution for our retrofit.

Pumps Cut Maintenance by Almost 70%
After the August 2013 retrofit, workers went from a daily pump maintenance routine to weekly check-ins at the lift station. We’re spending an estimated 67% less time there. Instead of dropping everything to respond to alarms, crews are conducting preventive maintenance on other key equipment.

The old pumps were serviced by sending a maintenance worker into the 30-foot drywell via a small elevator. The new pumps are lifted out of the pit via a guide rail system, a common option that reduces the time and cost of removing pumps from basins. Sending someone down the equivalent of a three-story hole was a safety issue for us. Now, it’s no longer a worry.

Advanced Electronics to the Rescue
Reliable, trouble-free operation is one reason we’re doing less maintenance. The other is a predictive management control and monitoring package that includes:

User-friendly controls. Instead of ball floats, the CU362 controller’s far-more-reliable transducer regulates on and off states. An employee can learn to operate the intuitive controls in five minutes. The old controller didn’t give us much information; the new controls detail what’s going on at the site.

Remote operations from a smartphone. The pump’s software enables employees to monitor system status and make real-time adjustments to the controller at their desks, laptop, tablet, or smartphone.

They use the free GrundfosGO mobile app to change kickoff points, turn pumps on and off, and address other problems anywhere they can get a cellular or WiFi signal. For instance, if Station 2 has shut down, we can temporarily shut down Station 1 while we fix the other station.

The app also provides all the maintenance data field crews might need, from troubleshooting videos to part numbers. This eliminates panicked calls to customer support and racing back to the office to get information.

Electronic motor protection. To address fluctuating electricity patterns, we chose the MP204 motor protection module, which continually monitors station voltage, pump current, current asymmetry, power, and energy consumption; and tests the insulation resistance of the pump windings when not in operation (Megger test). If any of these levels travel outside acceptable limits, the system issues an alert and automatically shuts down the pump.

Our old control software issued generic alerts that didn’t indicate the cause of an alarm. The new software issues condition-specific alarms that help us decide whether to send a mechanic or an electrician to the station.

Clear chain of command. If sensor thresholds are exceeded or a pump or controller reports an alarm, an SMS (text message) and e-mail is instantly sent to whoever’s on duty.

The new system lets supervisors designate the employee to be notified depending on date and time. If the employee doesn’t acknowledge the alarm, the system automatically notifies a list of backup workers until the alarm is addressed.

Immediate Payoffs
The software can be used to schedule maintenance. For example, a supervisor might be notified after a specified number of starts, indicating it's time to change the oil. In addition to eliminating paperwork, programming the pumps to report specific operational issues enables us to invest maintenance dollars more effectively.

Our team also uses the mobile app to create reports that pinpoint the sources of problems. This diagnostic capability proved the new system’s worth the night it was installed.

"The Riverside pumps shut down because something was wrong with power quality," says Cummings. “Using the remote management software and smartphone app, we were able to determine, for the first time, exactly what was happening.”

The new pumps use three-phase power. The Riverside lift station is located at the end of a residential neighborhood. When homes are drawing single-phase power for things like air conditioners and electric heaters, the station often receives two phases with low current and one phase with high current. This produces a current asymmetry fault, where current draw on all three phases isn’t balanced.

Severe and recurring power asymmetry can burn a pump out in short order. Before we had motor protection capabilities, we could only assume this was the cause of the frequent outages.

“We were able to prove the shutdowns were caused by the incoming electrical feed,” Cummings says. “This evidence allows us to work with the power utility to address the problem.”

Today, our crews are immediately notified of harmful power fluctuations and other pump performance warnings. The mobile app allows our team to print reports documenting the asymmetry.

"If the asymmetry exceeds about 20%, the electric utility gets an alarm identifying the problem,” says Cummings. “If it happens too many times, the pumps are shut off as a protective measure.”

Following a year’s worth of service, about 2,200 hours of run time with no failures, there has been a dramatic reduction in energy use due to the pumps’ highly efficient motors (85.8% efficient at full load). In fact, the electrical savings paid for the new pumps during the first year of operation.

According to Cummings, our monitoring and control equipment has been available in the U.S. since July 2013. Many of the 80 installations since then have been by utilities that tried the system at one station and, after seeing its benefits, incorporated it at additional stations.

That was certainly true in our case. We’ve installed the electronic controls in a second lift station and replaced old pumps with the Grundfos pumps at other stations. We now have six of the intelligent, demand-based wastewater pumps boosting our network’s overall performance.