Dec 12, 2002

Clogging at Pump Station

In 1971, the Falmouth, Maine, wastewater collection system began operation with 23 miles of sewer line and seven pumping stations handling more than 450,000 gallons a day. An integral component of this system is the Brown Street Pump Station #2, which pumps continuously into an interceptor trunk line and handles a large portion of the residential wastewater in south Falmouth.
This station, which was part of the original collection system installation, is an underground, packaged Custom Series Pump Station by Smith & Loveless. Designed for 420 gpm @ 72' TDH with 1800 RPM motors, it contains a Variable Frequency Drive (VFD) that was installed in 1991.
As the town grew and the wastewater constituents changed, Mark Damon, town of Falmouth collection system foreman, noticed an increase in the amount of maintenance required to keep Brown Street Station #2 running smoothly. In particular, the station was beginning to clog, requiring a monthly routine to unclog the pumps. Through troubleshooting, Damon identified several things that were contributing to the clogging issue. He discovered that the piping layout caused the wastewater to drop directly over the suction line of the pump, which was collecting debris and clogging the pump?s impeller.
Damon also found that the station?s VFD was contributing to the problem. The VFD facilitates lower pump RPM during low flow periods, which can at times cause backup. These items, along with stronger residential waste constituents like paper towels and toilet paper, would routinely bind together creating an extreme clogging condition. The service interruptions were not only inconvenient, they were steadily increasing the town?s operation and maintenance costs.
When the station?s clogging frequency increased to weekly, Damon contacted the Smith & Loveless After Market Division looking for solutions. He was introduced to the X-PELLER? ? a new, mono-port pump impeller designed specifically for extreme clogging problems such as his application. This pump is dynamically balanced through the full trim with less than 3 mil vibration. Its unique mono-port flow design effectively expels high volumes of stringy materials and rags that can clog wastewater pumps.
After the new X-PELLER was installed, Damon slowly eased the newly upgraded pump back into rotation ? not knowing what to expect. After more than six months of trouble-free operation, Damon indicated that the pump clogging issue is a thing of the past.
?Since we installed the new X-PELLER, we have not had to pull the pump once due to clogging,? he reported.
The X-PELLER installed in the Brown Street Pump Station is now helping to save time and maintenance costs for the Town of Falmouth. It comes in 900, 1200 and 1800 RPM models and is fully trimmable at the factory or in the field to specific pumping conditions.