At the Mahanoy City Wastewater Treatment Plant (WWTP) in Pennsylvania, United States (U.S.), it’s oh-so-quiet.
Unless told otherwise, you wouldn’t know that a 36-inch (91-centimetre) diameter pump, close by, operates night and day in a giant concrete basin. Even when one of the two larger screw pumps, at 84 inches (213 centimetres) in diameter, is being put through its paces, there is still a remarkable hush.
And with the town’s school district just 300 feet (91 metres) away, this well-run treatment plant is a good neighbour.
However, the calm is an altogether different story from previous dramas Mahanoy City WWTP experienced. The original 36-inch-in-diameter (91-centimetre) raw sewage enclosed screw pump, which had become increasingly unreliable, failed twice, and ultimately gave plant operators no choice but to look for a more sturdy and efficient alternative. A heavy-duty enclosed Type C screw pump from Lakeside Equipment Corporation was chosen for its design with two convoluted flights that are welded to the rotating outer tube, with the lower bearing mounted above water level.
“Through Lakeside’s representative Doug McCord in Exton, Pennsylvania, we’d always had a very good relationship – and with this new Lakeside enclosed Type C screw pump we immediately benefitted from an intelligently designed and very well engineered product,” Josh Bell, Mahanoy WWTP’s Assistant Chief Operator, Josh Ball, commented.
The smaller pumps, installed in the deeper part of the wet well, has only needed minimum maintenance since its installation – just a weekly treat of oil and grease, and a change of oil twice per year. For the two new larger screw pumps, an oil change is required just once a year.
“In this volatile environment, it is only stainless steel that ultimately survives,” Ball explained.
“We aimed to bring about the best and most long-lasting solution for Mahanoy City. This scale of pump installation is a significant investment and needs to be applied with the utmost precision,” Doug McCord, speaking on behalf of Lakeside, added. “Lakeside used all of its vast engineering, fabrication, machining and aligning experience to bring about a truly first class job.”
“We do, of course, carry out regular visual inspections. But all three enclosed Type C pumps are extremely reliable. Doug and Lakeside are helpful as well as consistent, and always apply common sense,” Bell continued. “Compared to the previous cross-start motors on the old pumps, the Lakeside Type C’s are also more efficient, using far less energy. When needed, the capability of these pumps also gives us the advantage of being able to clean out the well without going over the bearings. The power is there to bring it down to operating levels very quickly.”
He concluded, “We have a new soft start-up with 200 HP motors, but it is incredible that the Lakeside pumps are so quiet. In fact, when we first had them installed, we couldn’t hear anything, so we had to go outside to check that they were running! If we’d had loads of noise from the start-ups and constant humming, it could have led to possible complaints from the school district that’s so close to us, but because of the very high quality work by Doug McCord and Lakeside, everything is running smoothly and quietly. The difference between how the old pumps used to sound is like night and day – and we’ve also seen a big improvement in reliability.”