Case Study 01.2018

Zerbe Township WWTP
Successfully Manages
Non-Dispersible Debris
Impacting Its Influent
Pump Station
Wastewater treatment plant operators,
having to deal with persistent clogs
in pumps and check valves due todisposable wipes and other nondispersible debris, have had limited
options for solutions that can be
implemented within narrow and deepchannel influent pump station wet
wells. Zerbe Township, Pennsylvania,
is one of a growing number of WWTP
operations that have successfully
managed this problem by installing
Gorman-Rupp Super T Series® selfpriming pumps, upgraded withan innovative Eradicator® Solids
Management System.
For decades, wastewater treatment plant operators
have dealt with clogging problems at their wastewater
treatment plants (WWTPs) and pump stations, but themeteoric rise in the use of disposable wipes and othernon-dispersible products has accelerated the problem
to epidemic proportions in just about every developedmunicipality worldwide that relies upon a functioning
wastewater treatment system.

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Wet-wipe consumption overall has nearly tripled in thepast decade, according to Smithers Pira, a worldwide
authority on the packaging, paper and print industries.
When these reinforced paper towels, cleaning
cloths, baby wipes, diaper liners, feminine hygieneand cosmetic wipes are flushed down the toilet,
they ultimately reach the influent pump station atwastewater treatment plants relatively intact – clogging
and jamming pumps, check valves and screens, andsignificantly increasing the maintenance, repair andoperational costs.
Influent pump stations, being the headworks ofwastewater treatment plants, are the first processes
impacted by non-dispersible debris. If the pumpstation has a coarse-bar screen positioned before
the pumps, as with many legacy systems, some of
the non-dispersible material will be captured before
reaching the pumps. But these original-equipment
screens, with their 1” to 2” openings which may have
performed satisfactorily for decades, are now proving
inadequate at stopping the greatly increased flow ofnon-dispersibles, allowing this material to reach thepumps, which negatively impacts their operation,requiring more frequent shut-downs to perform cleanouts, maintenance and repairs.
Upgrades made to pump stations have primarily
focused on the pump replacement aspect with limited
regard given to non-dispersible products in the waste
stream. Original-equipment coarse-bar screens,when they are even present, are usually left in place,and when screen upgrades are initiated, they are1

unfortunately located downstream of the new pumps
due to the limited narrow configuration of the existing
wet well. Screening is recommended to protect pumps
and other equipment from debris-laden influent
sewage entering the wastewater treatment plant.
Consequently, even when pump upgrades are initiatedin pumping stations, the performance of the newpumps is still compromised from the overwhelming
influx of non-dispersibles.

Zerbe Township WWTP
This circumstance is precisely what the Zerbe Township(Zerbe) WWTP encountered in 2016, after upgrading its
primary influent pump station in the year prior.
Zerbe Township, located in Northumberland County,
Pennsylvania, encompassing the town of Trevortonwith approximately 1,900 residents, recently upgraded
its WWTP to bring it into compliance with both thePennsylvania Sewage Facilities Act 537, and theChesapeake Bay Total Maximum Daily Load (TMDL).
Act 537 requires municipalities to develop andimplement comprehensive plans that provide for theresolution of existing sewage disposal problems, andfor future sewage disposal needs of municipalities,
under the oversight of the Pennsylvania Departmentof Environmental Protection (DEP). The TMDL wasestablished in 2010 by the U.S. Environmental
Protection Agency (EPA) to restore clean water in theChesapeake Bay and the region’s streams, creeks andrivers. The TMDL set pollution limits equivalent to 2004
EPA standards on nitrogen, phosphorus and sediment,with specific deadlines for implementation.
Originally built in1963, the Zerbe treatment plantconsisted of two primary clarifiers and a drying bed,
which decanted into Zerbe Run, flowing into Mahanoy
Creek, the Susquehanna River and ultimately theChesapeake Bay. Prior to the implementation of TMDL,
the Zerbe WWTP’s nitrogen, phosphorus and sediment
discharge loads were considered non-significant. But
under the TMDL mandate, Zerbe’s treated effluent
concentration for nitrogen, phosphorus and sediment
discharges were reduced, in conjunction with anincrease in hydraulic capacity to 0.5 MGD that wasrequired under Act 537. These changes necessitated asignificant plant upgrade to an activated sludge SBR
process, and required increased influent pump capacity2

Gorman-Rupp Super T Series® pumps can bemounted above the liquid being pumped.
Should service or maintenance be required, it
can be easily performed using common handtools and without disconnecting piping.
within the existing pump station. These plant upgrades
were initiated in 2014 and completed in 2016.

Upgraded Influent Pump StationThe duplex pump station was upgraded with heavyduty solids-handling pumps, manufactured byGorman-Rupp Pumps. The self-priming, centrifugal
Super T Series® 6” pumps, are located in a nonhazardous area above and separated from the wetwell. The self-priming suction lift design of the pumps
allows the design engineer to physically locate thepumps where access is a non-issue and routine
maintenance can be completed quickly and easily.
“The pumps’ superior solids-handling capability makes
them ideally suited for Zerbe WWTP’s application ofhandling solids-laden liquids and slurries,” said SteveSolon, Sales Engineer with Envirep, Inc., which specified
and installed the new pumps. “Each pump provides amaximum capacity of 1,050 GPM, equal to three times
the average influent design flow rate.”
The large volute design allows automatic repriming© 2014 ©
The2018
Gorman-Rupp
Gorman-Rupp
CompanyPumps

in a completely open system without the need forsuction check valves, even with the pump casing
only partially filled with liquid and a completely dry
suction line. Their two-vane, semi-open solids handling
impellers handle up to 3” diameter solids. Pump outvanes on the impeller shroud reduce foreign materialbuildup behind the impeller, and reduce pressure
on seals and bearings. Additionally, double-floating,self-aligning, oil-lubricated mechanical cartridge seals,
with stationary and rotating faces of silicon carbide, arespecifically designed for Zerbe’s abrasive wastewater.
“Directly downstream of the influent pumps, anEnviroCare screen was put into place, which removed
unwanted solids prior to the wastewater treatment
process,” added Solon.
“Ideally, a screen would be installed before the pumps,
but at Zerbe that could not be done. The existing
influent wet well was fairly deep, and there wasinadequate space to install a screen.”
Since the influent pumps are located before the screen,
the pumps had to deal with a significant quantity ofdisposable wipes and other non-dispersible material
from the collection system. Although the frequency
was considerably less than with the original pumps, theplant was still experiencing jams and clogs.
“With the Super T Series pumps, the incidence ofclogging is reduced compared to most other heavyduty solids-handling pumps,” continued Solon. “Theunique impeller design and the ability to adjust
clearances between the impeller and the wear plate
help to reduce clogging. If a clog does occur, themaintenance time is much less – the front cover plate
can easily be opened to remove the jammed debris.”2
3

Eradicator® Solids Management
System
To minimize the clogging issue, Envirep
recommended that Zerbe install an Eradicator® SolidsManagement System to each pump. Recently released
by Gorman-Rupp as an add-on to existing Super T
Series pumps, the system provides an aggressive
self-cleaning wearplate incorporating a number ofnotches and grooves, as well as a lacerating tooththat helps break up stringy material, scrape it off
the impeller vanes and pass it through the pump.
Installation is done without impacting performance orinterrupting service.
“Eradicator-equipped pumps
do not require expensive
chopper blades that need
periodic replacement,
but rely on passing
large solids and stringy
materials straight
through the pump,”
said Solon.

The Eradicator® Solids
Management System’slightweight inspection coverallows for easy access to the impeller for routine
maintenance and clearing blockages.
The self-cleaning wearplate shreds stringy
materials to further reduce clogging.

Even though the new pumps make for much easier andfaster clean-outs, it would still take an hour to open up
the pumps, clean out the debris, and close them up.

The system provides a special lightweight inspection
back cover that can easily be removed if it is necessary
to inspect the impeller. The lighter coverplate makes it
easier and safer to perform routine inspections.

“We still needed to clean out the pumps and the checkvalves, at least once or twice per week,” said Ed Reed,Chief Operator at Zerbe WWTP. “HandiWipes, baby
wipes and that sort of stuff, they do not grind up in
centrifugal pumps, they just pack in and wedge thepumps’ impeller.”“The Eradicator has definitely reduced our clogging,”
continued Reed. ”Since we put in the upgrade kits
six months ago, we have not yet had to open up thepumps to clean them out to remedy a jam or clog. We
have done nothing more than routine maintenance onthe pumps.”© 2014 ©
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Gorman-Rupp
Gorman-Rupp
CompanyPumps

The Eradicator is available as a retrofit kit on existing
Super T Series pumps already in the field, and includes
all components needed to make an easy conversion.
“Since this system came out, we have been
recommending it to our plant operators as an add-on
kit upgrade to their Super T Series pumps,” explained
Solon. “Many wastewater treatment plants, like Zerbe,
have to deal with pumps clogging from wipes, and theEradicator is solving that problem for them.”“Our inflowing pump station is now functioning with an
improved operational efficiency,” added Reed. “We haveincreased pump uptime, and reduced maintenancetime and costs.”

About Envirep, Inc.
Envirep, Inc. is a manufacturer’s representative serving
the municipal and industrial water and wastewatermarket in Eastern Pennsylvania, Southern New

Jersey, Maryland, Delaware, District of Columbia,and Northern Virginia. The company represents
manufacturers of equipment used to pump, treat anddispose of wastewater and biosolids. It also represents
manufacturers of equipment used to pump, treat,
distribute and store potable water.

About The Gorman-Rupp Company
The Gorman-Rupp Company is a leading manufacturerof pumps and pumping systems for the municipal,water, wastewater, sewage, industrial, construction,
petroleum and OEM markets. The company’s
Engineered Systems operation also manufactures afull line of water pressure booster stations including
pumps, motors, valves and controls – all housed inweather-proof fiberglass enclosures – meeting about
any municipal water supply need.
Ultimately, Gorman-Rupp prides itself on manufacturing
and delivering the right pump for the job.

GORMAN-RUPP PUMPS | P.O. BOX 1217 | MANSFIELD, OHIO 44901-1217 | USA | 419.755.1011 | GRSALES@GORMANRUPP.COM | GRPUMPS.COM24© 2014 ©
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Gorman-Rupp
Gorman-Rupp
Company
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