Last month, we ended part 1 of this series by introducing the BJM Pumps Series SKG pump, which features RAD-AX® shredding elements cast in hardened 440C Stainless Steel (Rockwell hardness above 55C). This design provides unsurpassed solids passage efficiency through its impeller and volute and is available with 2, 3, or 5 horsepower high torque 4-pole motors. These pumps are perfect for smaller waste water stations, and in this month’s conclusion, we’ll look closer at one such success story.
A CASE STUDY: WIPING OUT A WASTEWATER PUMPING PROBLEM
FoxRock Properties owns and operates two massive office and medical complexes in Norwell, Massachusetts. The first of the neighboring properties is Longwater Place, a 27,000-square-foot office building, part of a larger 26-acre campus including 84,000 square feet of corporate offices and a 160,000-square-foot wellness center. Longwater Place incorporates a full cafeteria and fitness center, featuring a gymnasium with squash courts and locker/shower facilities.
The adjoining property is South Shore Medical Center. The 85,000-square-foot facility comprises 100 medical examination rooms, 70 medical offices, and a complete range of diagnostic equipment.
With the size of these commercial buildings, you can easily imagine the wastewater handling challenges faced by property management. There are 30 bathrooms and 64 toilets throughout the complex. Flow content includes sanitary waste, wipes, and feminine hygiene products flushed by staff, patients, and visitors. All of it travels through the sewer lines of both properties and is funneled into an outside 10,000-gallon over-flow tank. The wastewater is then pumped through a 4-inch PVC discharge pipe over one-eighth of a mile from the tank into the municipal sewer system. Two solids-handling submersible pumps are at the heart of the system.
EFFECTIVELY HANDING MUNICIPAL DISCHARGE
Although not required by local regulations, FoxRock Properties maintains this pumping system to ensure that discharges to the municipal sewer system can be handled effectively by the local treatment facilities.
The property manager for FoxRock, Dan Snyder, explains, “Given the buildings’ populations, professional range of clients and types of services provided, it is expected that we would see more than our fair share of flushables.”
He goes on, “In the past we experienced frequent failures as wipes blocked screens protecting the pumps and wrapped around impellers, clogging the volute, and eventually burning out the pump’s submersible motors. Even with a back-up pump in place, the service interruptions and maintenance costs became unacceptable.”
The average pump service life was under 1.5 years. After one of the 460-volt submersible pumps failed again, Snyder decided to ask the water and waste equipment specialists at Williamson New England Electric Motor and Pump Company to take a look at the problem and recommend a solution to the pump failures.
ADDRESSING HEAVY WIPE CONTENT
Jae Wilson, service manager at Williamson New England Electric Motor and Pump Company reviewed the system and its hydraulic requirements including the difficult-to-pump wastewater content.
Although there are numerous solids-handling pumps available, none presented the perfect solution. Research indicated that the heavy wipe content would still tend to wrap and clog pumps with traditional non-clog impellers. The resulting failure meant lifting the pump, disassembling and manually clearing the blockage, and possibly replacing the motor.
Jae consulted with one of his premier pump suppliers, BJM Pumps which manufactures a wide range of non-clog submersible shredder pumps for industrial and municipal services. The timing could not be better. BJM Pumps offered Jae an opportunity to install one of the first of a new line of shredder pumps, the SKG Series with RAD-AX® technology. This new design would be perfect for the application since it used both radial shearing and axial cutting to pass hard to pump items such as wipes. The required pump was immediately available and quickly installed.
One important advantage was immediately noticeable. Most non-clogs, including the second wastewater sump on the FoxRock property, need to be surrounded by a screen. The solids and debris that get caught in that screen need to be routinely cleared by hand. The BJM Pumps SKG does not require a screen. A post installation inspection revealed no debris in the sump.
Dan Snyder adds, “So far I am very happy with the pump. It was installed in July 2014 and continues to operate without clogging.”
THE OPTIMUM PUMP FOR THE JOB
It is impossible to prevent non-flushable materials from entering the wastewater system but at least FoxRock Properties now has the optimum pump in place to minimize the possibility of clogging. It should also improve the downstream conditions since any solids pumped from the property into the municipal system can be easily handled.
For More Information
Brian Mitsch, P.E., is vice president of operations and engineering for BJM Pumps. BJM Pumps is headquartered in Old Saybrook, Connecticut, and has been providing fluid handling solutions for industrial and municipal services since 1983. Over its thirty-three year history, BJM Pumps has grown quickly by supplying world class pumps and accessories, priced competitively, through its global network of stocking distributors.
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MODERN PUMPING TODAY, August 2016
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