Grinding Down Pump Station Repair Costs
Grinder eliminates debris while reducing cleanup costs
When Otter Creek Water Reclamation District was faced with expensive reoccurring cleanup costs at its largest wastewater pump station, engineers solved the problem with the Muffin Monster, a wastewater solids reduction technology.
The village of South Elgin, Ill., established in 1897, is a picturesque community attracting visitors and new residents with its "old world" charm. Located about 40 miles northwest of Chicago, the village’s 22,000 residents rely on three wastewater pump stations. The largest of these is located at the Thornwood Lift Station where flow to the station is about 490 gal per minute (gpm) (110 cubic meters per hour), and three 40-hp (30-kilowatt) pumps need to move sewage at about 600 gpm (136 cubic meters per hour) at 36 ft (11 meters) TDH. Here, buildup of rags, trash wrappings and other debris were clogging the system and forcing it offline. This necessitated regular cleanings totaling more than $19,000 per year.
The water and wastewater systems within the southwestern portion of South Elgin, including the Thornwood Lift Station, are owned and operated by Otter Creek. RHMG Engineers serves as the district engineer, and Otter Creek contracts with South Elgin for the operation and maintenance of its system. According to Dave Jaeschke, RHMG’s senior environmental engineer, they were running into a new and growing problem.
“Pumping stations and sewage treatment plants are filling with more and more polyester-reinforced rags; baby wipes, mop heads and cleaning wipes used in restaurants and homes,” he said. “Because of the polyester fibers in them, they don’t break up or decompose in wastewater. Eventually this debris builds up and clogs pump impellers to the point it shuts down. As a result, we were forced to hire a vacuum truck four times a year to the tune of $4,900 a pop to clean out the rags from the wet well.”
In addition to the rags building up in the wet well, they accumulated over the cables leading to the submersible pumps. Over time, the weight would disconnect the cables, inadvertently shutting off and short-circuiting the pumps. Pumps had to be either reset or completely rebuilt. Both scenarios required expensive equipment to pull up the pumps.
A Cost-Effective Solution
When you add the pump maintenance costs to the $19,000 per year wet-well cleaning costs, the numbers quickly skyrocket.
To combat these soaring expenses, RHMG proposed installing a JWC Environmental (JWCE) Muffin Monster to grind up the debris. The grinder would not only eliminate the quarterly cleaning and protect the three pumps, it also would improve energy efficiency (i.e., without impairment from rags, the pumps wouldn’t need to go on and off as often, reducing wear and tear).
The Muffin Monster model 30005-0024, which handles flow rates up to 1,000 gpm (230 cubic meters per hour), was selected for the Otter Creek wastewater pump station. The grinder is a low-speed, high-torque grinder with sharp steel cutter teeth that quickly shreds rags, rock, wood, clothing, plastics and other debris into confetti size particles that won’t clog pump impellers. This allows the wastewater to flow smoothly though pumps and pipelines to the wastewater treatment area.
To install the grinder in the inlet system, JWCE’s custom stainless steel guide rails were attached to the sides of the wet well. Then the grinder was slid down into place about 20 ft below so that it fit perfectly in front of the influent pipe.
Since the grinder’s installation a year ago, there has been no need to bring in a vactor truck for cleaning, nor have there been any pump maintenance issues.
“The [grinder] still looks brand new and there are no signs of wear,” said Dan Mann, water & sewer superintendent for South Elgin. “The savings are really unbelievable. In addition to the savings on expensive wet-well cleaning costs, a huge savings was realized by no longer having to pull up pumps and perform maintenance.”
For more information, contact JWC Environmental at [email protected] or 800.331.2277.
http://www.wwdmag.com/sites/wwdmag.com/files/imagecache/article_slider_big/fallwinter2011805%20new.jpgSouth Elgin staff inspect the grinder and underground wet well.
http://www.wwdmag.com/sites/wwdmag.com/files/imagecache/article_slider_big/fallwinter2011803%20new.jpgThe grinder is installed in the underground pump station.
http://www.wwdmag.com/sites/wwdmag.com/files/imagecache/article_slider_big/Cutters.small%20new.jpgThe grinder's hardened steel cutters slice through rags.