Storm Water Pump Station Design Guide

8/9/2019 Storm Water Pump Station Design Guide

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STORM WATERPUMPING STATION

DESIGN GUIDE


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CONTENTS

1. Introduction 2

. Introduction to Grundfos

. Introduction to ooding . Introduction to ood control

2. The sources of ooding - and the solutions 10

. Can we prevent ooding? . . Flood management

. . The ood risk cycle . The sources of ooding . Flood control solutions . . Drain/rain water station . . Network pumping station . . Main pumping station . . Storm water tank with installations

. . Pump gate pumping station . . Flood control pumping station . . Grundfos Remote Management System . Flooding, then what? . . Water-borne illnesses and water contamination . . Drainage pumps and service trucks . . Filtering and disinfection

3 Designing a ood control pumping station 22

. General considerations . . Design sequence . Design conditions . . Flow patterns and boundary geometry . . Types of installation . . Water ow (Q) . . Head (H)


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CONTENTS

. . Water velocity . . Power supply and backup . . Trash racks and screens . . Handling sludge . Pump selection . . Axial ow propeller pump or mixed ow pump? . . Number of pumps . . Pump selection / determine column diameter . . Minimum submergence (S) . . Turbulence Optimiser™ . . Sensors in the pumps . Dimensioning the pumping station . . Terminology and conventions . . Different station layouts . . Pump bay design . . Pumping station dimensions . Duty strategy – reducing minimum water level . . Grundfos dedicated controls . . Communication modules SCADA implementation . . Grundfos Remote Management (GRM) . . Motor Protection (MP ) . . Variable frequency drives (CUE) . . Soft starters . Other considerations for the construction . . Support beams and columns for the building

4 CFD and model testing 60

. Computational Fluid Dynamics (CFD) . Model testing

5 Vortex – and how to prevent it 64

. Types of vortices

. How to prevent vortices . . Sub surface vortices . . Submerged vortices . . Air-entraining vortices . Retrotting FSI, Formed Suction intake . Retrotting back-wall and oor splitters . Reducing surface vortex by retrotting a baffle

6 Accessories 70

. Column pipe . Anti-cavitation cone . Splitters . Cable entry . Cable support system . Monitoring unit . Formed suction intake (FSI)

7. Grundfos service and solutions 76

8. Glossary 80

9. Appendices 84Appendix 1: Head loss calculations Appendix : Grundfos products Appendix : List of references Appendix : Lloyd certicate

The design recommendations in this book are general guidelines that do not just apply to Grundfos pumpsand solutions. However, Grundfos cannot assume liability for non-Grundfos equipment used according tothese recommendations.

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1. INTRODUCTION

1

Who is this handbook for?

This book is intended to assist application engineers,designers, planners and users of sewage and storm watersystems to incorporate axial and mixed ow pumps.

The guidelines in this book and especially the pumpingstation design can be used as they are, or be adapted tospecic requirements and guidelines.

Additional informationIf you need additional information that does not specically concern ood pumping station design, perhaps the followingGrundfos publications can be of help:

You can nd all Grundfos publications in WebCAPS at www.grundfos.us

Based on the ANSI standardGrundfos Chicago was on the ANSI standard workingcommittee for the American standard for pump intakedesign. Therefore, many of the guidelines and recommen-dations in this book are based on the design standardsof the American National Standards Institute (ANSI) thatGrundfos helped dene.

Grundfos Water Utility specialistsGrundfos specialists from our Water Utility CompetenceCenters, local Grundfos sales engineers, and our onlinepublications are at your disposal and available to offerwhatever assistance you need.

3STORM WATER PUMPING STATION DESIGN GUIDE INTRODUCTION

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GRUNDFOS WASTEWATERSTORMWATER TANKS

DESIGN OF STORMWATER TANKSRecommendationsandlayout


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1.1 Introduction to Grundfos

Grundfos is the world’s largest pump manufacturer and a full line supplierof pump solutions within water supply, wastewater, buildings services, andindustry.

With Grundfos companies located across the US, we offer local expertise andsupport wherever you are.

We support the planning, designing and commissioning of pumping systems,and we deliver the technology that can meet our customers’ objectives.

Experts in ood controlWith our innovative and reliable ood control solutions we can go furtherthan most to prevent ooding in a nancially and environmentally sustain-able way. Our insight can be applied to addressing the key issues of safe-guarding people, crops, business and the entire infrastructure.

Over the years Grundfos has pioneered numerous innovations that havebecome or are becoming industry standards. And we will continue to be atthe forefront in promoting and facilitating energy efficiency and sustainabletechnology.

It is these innovations that will enable us to meet future challenges, higherdemand and stricter regulations within ood control. Our commitment isto play a strong part in the bigger picture, to prevent ooding or reduce theconsequences of it. People worldwide depend on it.

Grundfos ood control installations worldwide

1 5 INTRODUCTIONSTORM WATER PUMPING STATION DESIGN GUIDE


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Source: UNISDR

STORM WATER PUMPING STATION DESIGN GUIDE INTRODUCTION 7

Flooding is not just the most common cause of disaster inthe world; it is also by far the fastest growing.

However, not all oods are alike. Some oods develop slowly,while others, such as ash oods, can develop in just a fewminutes even without visible signs of rain. Some oods arelocal, impacting a neighborhood or community; others arevery large, affecting entire river basins and multiple countries.

Inland ooding is the most common type of ooding event.It typically occurs when waterways such as rivers or streamsoverow their banks either as a result of slow ooding due tosustained heavy precipitation like monsoons or snow melt.

Unexpected oodsBut ooding can also hit where you don’t expect it at all.Unusual weather patterns can – and do – cause unexpectedstorms and heavy rains in regions where historical data

has offered no warning. Recent years have provided manyexamples of such unexpected oods in both Europe and Asia.

Coastal oods are also very common as a result of high tidesafter storms and increased sea water levels may occur quicklyas a result of storms, hurricanes or even a tsunami.

Affected regionsRegions all over the world are affected by ooding. However,for countries with large overpopulated cities the consequen-ces are the worst.

Major cities in Europe, the USA, and Asia, including KualaLumpur, Jakarta, Bangkok, and Shanghai, all have oodingproblems. Indeed, any region faced with high annual rainfalls,increased populations, and expanding cities will be called uponto place increasingly great focus on ood control in cities.

1.2 Introduction to ooding

1


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Common to all oods is that they cause catastrophicconditions for all people and animals affected by theooding. Firstly, there is the physical damage of theinfrastructure to actual casualties both to humans andlivestock. Secondly, there is the contamination of thedrinking water which can lead to diseases and the lossof crops and food supply.

Due to climate changes and an increase in the popula-tion and urbanization the amount of ood scenarios hasincreased over the past decades and at the same timethe population has also become more vulnerable due toan increased settlement in low-lying areas and near riverdeltas.

Counteracting oodingBasic methods of ood control have been practiced sinceancient times: reforestation, dikes, reservoirs and ood-ways (i.e. articial channels that divert oodwater). Thesedays, oodways are often built to carry oodwater intoreservoirs where excess water is pumped into rivers.

With this handbook, we wish to use our expertise andexperience to provide valuable design tips in connectionwith the considerations of designing new pumpingstations for ood control.

We hope that the simple yet very important consider-ations when designing ood control solutions will benetmillions of people living in exposed areas all over theworld.

Flood control strategies usually cover the whole city.In practical terms, the solutions typically involve mul-tiple pumping stations at several locations to ensuresufficient ood management when nature bares itsteeth.

However, the decision to implement a ood controlstrategy is often made when it is too late: when aood has already happened, trailing major damagein its wake. In some cases, even a wake-up call ofthis kind is not sufficient; the ood is forgotten until,several years later, another incident occurs.

Flood control projects very easily become politicalbones of contention. There are, of course, nancialand practical issues to be considered, and it will betempting to focus on immediate problems ratherthan hypothetical disasters.

Even so, authorities should view ood protection as avital aspect of ensuring a safe environment for every-one. Ultimately, lives can be at stake.

1.3 Introduction to ood control Thinking ahead

INTRODUCTION 9 1 STORM WATER PUMPING STATION DESIGN GUIDE


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THE SOURCESOF FLOODING ANDTHE SOLUTIONS

History has repeatedly shown that there is noultimate solution to forestall and prevent oodingand fully secure people, livestock and infrastruc-ture.

Every year, nature and a changing climate set newrecords for the size of storms, rainfall intensityand tsunamis. This causes increasingly intenseepisodes and often in unpredictable geographicalareas.

We cannot create a complete guard against thesephenomena, but with the experience and know-ledge gained from each episode, we can constantlyimprove our ability to withstand ooding. We canminimize the risk for populations and livestock,and with our ability to handle the situation before,during and after ooding, we can limit the damageto infrastructure.

THE SOURCES OF FLOODING – AND THE SOLUTIONS 11 2

2.1 Can we prevent ooding?

STORM WATER PUMPING STATION DESIGN GUIDE

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2.1.1 Flood managementIn an effort to address ooding, we will use the EUood directive for inspiration. It identies all thefactors that should be taken into account and pro-vides clear requirements for individual countries:

• Preliminary ood risk assessment.• Flood hazard and risk mapping.• Flood risk management.

Cooperation across bordersIn this context, it is perhaps also important tounderstand that ooding knows of no borders aswaterways and shorelines are coherent. Floodingis a common problem and must be solved in coop-eration across borders.

We start where nature stopsAs a pump manufacturer, our contribution to theabove relates primarily to ood risk management.Through new technology, constant product deve-lopment, services and solutions, we continuouslyseek to meet the changing needs of the marketand our customers. In terms of ood control: Westart where nature stops.

2.1.2 The ood risk cycleThe concept of ood risk management is bulky andcan hardly be regarded a stationary nature. Ratherit is more like a cycle that continues to evolve.

To cover all elements, we use the following cycle todescribe the concept.

2

Preventive ood risk managementOur contribution to ood defense extends from householdsolutions to large scale management of water ows:

• Household drainage pumping stations and storm watersolutions.

• Network pumping stations handle rainwater in scatteredsettlements and urban areas.

• Main pumping stations in rainwater systems withassociated storm water basins

• Mega stations for handling water ows in tributaries tolarger rivers and outlet to the recipient or the sea.

• Supporting the design and project management duringthe planning and execution and commissioning of systemsand solutions.

Flood event managementGrundfos has developed operational solutions and servicesto handle ooding and improve reliability. These include:

• Operation of installations.• Concepts for service, preventive maintenance and

preparedness for existing installations.• Control and monitoring concepts for monitoring

the status and alarm functions. Post-ood measures

Immediately after a ood, a community faces greatchallenges. The population is at risk, as drinking watersupplies may be infected. To get the infrastructure backon track, sewage must be removed and entire areascleaned up.

• Pump preparedness for pumping of excess water– portable pump solutions

• Stationary and mobile disinfection solutions to maintaina drinking water supply.

13

Post ood measures• relief • cleaning

• reconstruction• organizational

and nancial aid

Preventive ood risk management• spatial planning• ood defense• retention• preparedness• insurance

Flood event management• early warning• reservoir control• evacuation• rescue

THE SOURCES OF FLOODING – AND THE SOLUTIONSSTORM WATER PUMPING STATION DESIGN GUIDE

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Pump gate2.3.5

Service7.0

Main pumping station2.3.3

Network pumping station2.3.2

Wastewater treatment plant

Rainwater collecting system

Drain2.3.1Stormwater tank

2.3.4

2.2 The sources of ooding

2

There are as many causes of ooding as there are natural phenomena. However, othersare man-made causes that increase the risk of ooding, triggered by the way we e stablishand organize our society.

Examples of settlements in high-risk areasand urban areas.

15 THE SOURCES OF FLOODING – AND THE SOLUTIONSSTORM WATER PUMPING STATION DESIGN GUIDE



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2.3.1 Drain/rain water station

ApplicationExcess water is collected in the well and pumped away fromthe house.

Grundfos solution: We offer solutions with integrated controland external control as complete units with inlet and outlet,and as single components. Flow: 80 - 160 gpmHead: 33 ft

Benets• Safety: Surveillance and alarm• Reliability

ProductsPumping stations: PUSTPumps: AP/KP/CC/DP/DWK/EF/DW/ AUTO ADAPT

www.grundfos.com/ood-control

2.3.2 Network pumping station

ApplicationCollects and distributesrainwater and stormwater.

Flow: 160 - 1,600 gpmHead: 230 ft

Benets• Flexible extension -> less piping and gravitation -> reduced

depth of main pumping station• Intelligent control between pumping stations• Combined with storm water tanks• Surveillance and alarm

Products

Available as pre-fabricated units or customized solutionsadapted to the existing infrastructure.

Pumping stations: PUSTPumps: SE/SL/S/DPK/DWK/ AUTO ADAPT Drives: CUEMonitoring: GRMControls: LC/LCD/DCAccessories: Pipes/valves


17

Despite the many causes, we will break downooding occurrences into the following:

1. Inland oodingPrimarily related to precipitation, either prolongedrain or intense local rain. Depending on the geo-graphical location, it can also be precipitation inthe form of snow and accelerated melting.

2. In deltasWhere rivers or waterways meet, bottlenecks

develop and block the water ow towards therecipient or the sea.

3. In coastal areasHurricanes and climate change can cause elevatedwater levels with the risk of ooding from the seawhich can also be caused by undersea earth-quakes followed by tsunamis.

Regardless of the source, a ooding threat is virtu-ally always a combination of these sources.

Often heavy inland rainfall and elevated sea levelsare connected, and elevated sea levels will affectinland river ows.

2.3 Flood control solutions

Grundfos offers a wide range of ood control solu-tions – from small solutions for private householdsto large-scale solutions that protect mega cities.

In the following, we will introduce some of themost common solutions and their natural applica-tions.

2 THE SOURCES OF FLOODING AND THE SOLUTIONSSTORM WATER PUMPING STATION DESIGN GUIDE

RAINFALL

STORM SURGE

EARTHQUAKE

FLASH FLOODS

I N L A N D

E S T U A R Y

C O A S T

RIVER FLOODS

COASTALFLOODS

TSUNAMIS

DISCHARGE

DISCHARGE

WATER LEVEL& WAVES

WAVES

KEY FACTORSTIME

RAINFALL



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2.3.3 Main pumping station

ApplicationReceives rainwater from pumping stations and gravitationsystems. Capable of handling large amounts of rainwaterand distributing it in large pipe systems. Flow: 1,600 - 32,000 gpmHead: 394 ft

Benets• Independent of gravity -> reduced construction costs• Intelligent control in combination with network pumping

stations, storm water tanks and other pumping stations• Minimizing the environmental and human consequences

of overow

ProductsSubmersible or dry installed pumps: SE/SL/S/ AUTO ADAPT Controls: LC/LCD/DCDrives: CUEMixers: AMG/AMDMonitoring: GRMAccessories: Pipes/valves


2.3.4 Storm water tank with installations

ApplicationThe concept of storm water detention is to temporarily storeexcess storm water runoff. This is to avoid hydraulic overloadof the sewer system, which could result in the ooding ofroads and buildings with untreated wastewater or its releasedirectly into the environment, causing pollution.

Flow: 1,600 - 8,000 gpmHead: 65 ft

Benets• Reducing peak ow and equalizing ow rates• Better utilization of the existing sewer system• Allowing for intelligent management of storm water ows• Savings on infrastructural investments

ProductsPumps: SE/SL/S/Flushjet/ AUTO ADAPT Controls: LC/LCD/DCDrives: CUEMixers: AMG/AFG/AMDMonitoring: GRMAccessories: Pipes/valves


2.3.5 Pump gate pumping station

ApplicationPump gates may bea reliable option if apumping station andreservoir are not anoption due to lack ofspace. If the outsidewater level is low,the pump gates andscreen will be open.Gravity discharges the inside water. Once the outside waterlevel gets higher, blocking the back ow, the pump gatesclose and block the rising water level. If the inside waterreaches a certain level, the pump and screen will start ope-rating to forcibly discharge the water inside.

Once the outside water goes down to a certain water level,the ood gate and screen open and discharge the insidewater by gravity ow. Flow: 2,400 - 1,600,000 gpmHead: 33 ft

Benets• Serves as a ood gate and pump simultaneously• Equipped with submersible pumps, the gates can be

installed on an existing waterway. May in some caseseliminate the need for a reservoir and pumping station

ProductsPump gatesPumps: KPL/KWMDrives: CUEMonitoring: GRMAccessories: Pipes/valves


2.3.6 Flood control pumping station

ApplicationA ood control pumping station manages extremely largeamounts of water owing in open canals at low heads. Thissolution demands a good infrastructure because of the largeinlet channels or pump sumps. Also, the power supply comesfrom a power plant, a dedicated power structure, or a combi-nation of them.

Flow: 2,400 - 1,600,000 gpmHead: 33 ft

Benets• Typically low operating hours -> high reliability• Protects large areas from ooding• Allows for settlements in areas that are exposed due to

climate changes• With or without water gate to the sea

ProductsPumps: KPL/KWMAccessories: Pipes/valvesDrives: CUEMonitoring: GRM


2

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2.3.7 Grun dfos Remote Management System

ApplicationGrundfos Remote Manage-ment is a secure, internetbased system for monitoringand managing pump installa-tions in commercial build-ings, water supply networks,wastewater plants, etc.

Pumps, sensors, meters and Grundfos pump controllers areconnected to a CIU271 (GPRS Datalogger). Data can be ac-cessed from an Internet PC, providing a unique overview of your system. If sensor thresholds are crossed or a pump orcontroller reports an alarm, an SMS will instantly be dis-patched to the person on duty.

Features and benets• Complete status overview of the entire system you

manage• Live monitoring, analysis and adjustments from the

comfort of your office• Trends and reports• Plan who receives SMS alarms with easy-to-use weekly

schedules• Plan service and maintenance based on actual operating

data• Share system documentation online with all relevant

personnel

2.4.2 Drainage pumps and service trucks

ApplicationThe Grundfos drainage solution ranges from small portabledrainage pumps for private housing, farms and small indu-stries to large-scale drainage solutions.

Despite their difference in size and application, they have allbeen designed for pumping drain water and are thereforeideal for ood-relief applications.

Flow: 80 - 160 gpmHead: 33 ft

Benets• Portable/movable• Plug and pump solutions• Easy to get to inaccessible disaster areas

ProductsPumps: Unilift CC /KP/DP/DW/DWK/PomonaDrives: CUEMonitoring: GRM


2.4.3 Filtering and disinfection

ApplicationMobile lter units for cleaning drinking water can be trans-ported by car or helicopter to disaster areas, where immedi-ate access to clean drinking is essential to prevent a danger-ous sanitation disaster.

Benets• Complete removal of suspended solids• Partial removal of dissolved matter (TOC, COD, BOD)• Removal of micro-organisms:

- Log 6 removal of bacteria (99.9999)- Log 4 removal of viruses (99.99)

• Superb quality as RO feed water (low SDI15)• Certi ed for use in potable water


2.4 Flooding – then what?

The solutions presented so far have all been preventive. Inother words, they have been designed to prevent oodingcompletely. However, if a ood occurs, either due to theabsence of a suitable solution or because the weatherphenomenon was so extreme that a ood was unavoid-able, there are also several solutions to minimize theconsequences of it.

2.4.1 Water-borne illnesses and water contamination

During a ood we hear about the deaths, displacements,economic losses, and causes associated with the ood.Less common immediately after a ood event, however, isattention to water-borne illnesses and water contamination.

Depending on location and sanitation conditions, infec-tious diseases are often spread through contaminateddrinking-water supplies. This includes:

• Flood water can contaminate drinking-water supplies,such as surface water, groundwater, and distributionsystems.

• Groundwater wells can be rendered useless from in-undation of water laced with toxins, chemicals, animalcarcasses, septic seepage, and municipal sewage.

• Surface water sources are impacted in similar manners.

To reduce the consequences of an actual ood, it is vital tohave emergency systems ready to take over when disasterstrikes. And immediate access to clean drinking water isessential to prevent a dangerous sanitation situation thatoften exceeds the consequences of the actual ood.

To secure clean drinking water supplies during and after aood, Grundfos offers a wide range of solutions tailored tothe specic situation and location.

DESIGNING A FLOOD CONTROL PUMPING STATION 23 3 STORM WATER PUMPING STATION DESIGN GUIDE


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DESIGNING AFLOOD CONTROL PUMPINGSTATION

3.1 General considerations

Good sump designThe sump design has a crucial impact on the pump’s totallifespan. It relies on an intake structure that allows thepumps to achieve their optimum hydraulic performanceunder all operating conditions.

The fundamental condition of a good sump design is opti-mal ow into the pumps – which is a uniform ow, free ofsubmerged or surface vortices and excessive swirl.

Poor sump designA less-than-optimal sump design could potentially result inpoor performance and/or mechanical strain due to vibra-tions and cavitation at the inlet to the pump(s).

A poor design can easily lead to sedimentation of sand andrags, which in turn can cause additional cavitation andvibration problems and excessive noise and power usage.

Sump design no goThe following phenomena should be prevented orreduced to a minimum in a properly designed pumpsump:

• Non-uniform ow at the pump intake: Results in excessive noise and vibrations, and re-

duced efficiency

• Unsteady ow: Can cause uctuating loads

• Swirl in the intake: Can create vortices and unwanted changes to the

head, ow, efficiency and power

• Submerged vortices: Can cause discontinuities in the ow and can lead tonoise, vibration and local cavitation

• Surface vortices: Can draw harmful air and oating debris into the

pump

• Entrained air: Can reduce the ow and efficiency, causing noise,

vibration, uctuations of load, and result in damageto the pump.

The negative impact of each of these phenomena onpump performance depends on the speed and the sizeof the pump.

Generally, large pumps and axial ow pumps (highspeed) are more sensitive to adverse ow phenomenathan small pumps or radial ow pumps (low speed)

For special applications beyond the scope of this book,please contact your local Grundfos Water Utility salesengineer, who will be more than happy to providethe expertise and experience you need to meet yourspecic needs.


DESIGNING A FLOOD CONTROL PUMPING STATION 25

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Flow patterns andboundary geometry(see 3.2)

2

3.1.1 Design sequence

When designing a pumping station, the design sequence is essential.Below, we present the typical progression in the design phase and what to consider.

90% OF ALLPROBLEMS

WITH PUMPSARE BASED INTHE INSTAL

LATION ANDTHE FLOW

CONDITIONSAROUND THE

PUMP

Pump selection(See 3.3)

Minimum water level(See 3.3)

Determine slope(See 3.4)

Cross-ow velocity(See 3.2.6)

Pump size and quantity(see 3.3)

Placing the pumps(see 3.3)

Velocity(See 3.4)

Dimensions(See 3.4)

1. How much water? (Flow)2. Coming from where?3. Going where? (Head)

Identify the column pipe diameter

Determine the minimum submergence of the pump and by that theminimum water level.Check NPSH at minimum water level.

Check the bottom elevation in the inlet channel and determine if itis necessary to slope the oor upstream of the pump bay entrance.Maximum slope 10°.

Compare cross-ow velocity (at maximum system ow) to averagepump bay velocity. If cross ow velocity exceeds 50% of the pumpbay velocity, a CFD study is recommended.

Determine the number and size of pumps required to satisfy therange of operating conditions likely to be encountered.

Determine the distance from pump bell mouth to oor

Check the pump bay velocity for the maximum single-pump owand minimum water depth with the bay width set to 2D.Max velocity 2 ft./sec.

Determine the dimensions of the pumping station.

3.2 Design conditions

Depending on the specic condition of the area and the location of the station, you can choosea pumping station design that meets your specic requirements.

Ask us for installation recommendations. We can often help you create a more efficient and durablesystem.

Choose the installation set-up that suits you With the Grundfos KPL and KWM pump solutions,the individual installation has the same scope forcustomization as the pumps themselves.

Installed directly in the column pipe, KPL and KWMpumps seriously reduce the need for constructionworks – so they can even save you money beforethey prove their efficiency in day-to-day operation.

COMBINING DIFFERENT PUMP SIZESALLOWS YOU TO OPTIMISE THE OPERATIONAND PUMP TO A LOWER LEVEL WITHOUT

DAMAGING THE PUMP INSTALLATION

ZONES OF STAGNATION SHOULDBE AVOIDED WITH FILLETS.

USE CFD MODELLING TO DETERMINE

WHERE THE ZONES OF STAGNATION ARE

1

Source: Adapted from

ANSI/HI 9.8-1998table 9.8.2.


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3.2.3 Water ow (Q)There are many conditions to consider when youare calculating pump station dimensions – suchas climate change, 10, 30 and 100 year’s rain, urbandevelopment and planning. General recommen-dations are therefore useless, as all calculationsdepend on your specic priorities.

Instead, we recommend that you follow the na-tional standards and legislations using the latesttools, such as MIKE URBAN and MI KE FLOOD from

DHI.

3.2.4 Head (H)Any dimensioning consists of a static and adynamic head.

The dimensioning head H = H geod + Hlosses (losses in pipes, valves, bends and aps etc).

Velocity headDischarging to an open canal where the waterows over a weir requires a special calculation.In this case, it is important to include the headcontribution H w from the increased water levelcreated by the ow velocity:

For more detailed information on this topic,please see Appendix 1: Head loss calculations,page 90.

3.2.5 Net Positive Suction Head (NPSH)Net Positive Suction Head (NPSH) describes conditions relatedto cavitation. Cavitation should always be avoided as it causesinefficient operation and is harmful to the installation.

What is cavitation?Cavitation is the creation of vapor bubbles in areas where thepressure locally drops to the uid vapor pressure. The extentof cavitation depends on how low the pressure is in the pump.Cavitation generally lowers the head and causes noise andvibration. It rst occurs at the point in the pump where the

pressure is lowest. Most often, this is at the blade edge in theimpeller inlet.

NPSH explainedThe NPSH value is absolute and always positive. NPSH is statedin feet [ft] like the head.

Two different valuesA distinction is made between two different NPSH values:NPSHR and NPSHA.

NPSHA stands for NPSH Available and expresses how close theuid in the suction pipe is to vaporization.

NPSHR stands for NPSH Required and describes the lowestNPSH value required for acceptable operating conditions. You

should always consider worst case scenarios or the full operat-ing range, when you use NPSH R and not only the specic dutypoint.

Free outlet from non-return ap Submerged outlet from non-return ap

TO SECURE SUFFICIENT HEAD IT IS IMPORTANT TO INCLUDETHE DYNAMIC HEAD, VELOCITY HEAD

g = 32 ft/s2v = Flow velocity [ft/s]Q = Flow [gps]b = Weir width [ft]

HW

Hgeod

V

M.W.L

M.W.L

H geod

M.W.L

H geod



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3.2.6 Water velocityAppropriate water velocity is essential for the reliability andthe efficiency of a pumping station.

To avoid sedimentation and build-up of obstructions it is im-portant to maintain sufficient velocity. However it is equallyimportant to keep the velocity low enough to prevent pres-sure losses and vortices in the pump bay.

Velocity guidelines• The velocity and distribution of the uid ow in the inlet

channel should be uniform. The angle of the bottomshould have an inclination of 10 to 15 degrees.

• The velocity of the water in the inlet channel should be lessthan 4 ft/s.

• The overall velocity of the water in the pumping stationshould be between 1 and 2 ft/s.

• If cross- ow velocity exceeds 50% of the pump bay velocity,a CFD study is recommended.

• The e ects of ow disturbances should be dissipated as faras possible from the pump intake.

• Stagnation regions should be avoided. If the design hasstagnation sections, they should be lled with concretebefore operation commences.

In the column pipeIf water velocity is too high =>pressure loss causing excessiveenergy consumption.

If water velocity is too low => sedimentation or up-concen-tration of solids makes the water heavier and causes themotor to trip on overload.

3.2.7 Power supply and backupIn some parts of the world, electrical grids are unstable andpower failures are common. Although Power outage is rare inothers parts of the world, they do occur and can be down-right dangerous if you’re not prepared.

Therefore, it is important to consider emergency situationswhere the regular power supply fails. A common solution isto install a backup diesel generator that can eliminate theheadaches of long-term power outages.

Please refer to EN752 and local legislation.

NPSH calculationsNPSHA can be calculated as:

Pbar – atmospherical pressure depends on your altitude.

Example:In practical terms for column installed axial ow pumpsthe calculation looks like this:

NPSHR + safety margin ≤ NPSHA (in all duty points)

NPSHR ≤ (Smin + 33 - safety margin) = Smin + 31 [ft]

REMEMBER TO ALWAYS CONSIDER NPSHR FOR THE FULLOPERATING RANGE, AND NOT ONLY AT THE SPECIFIC DUTY POINT.

A MINIMUM SAFETY MARGIN OF 2 ft IS RECOMMENDED, BUTDEPENDING ON THE APPLICATION, A HIGHER SAFETY LEVEL MAY

BE REQUIRED

ALTHOUGH RARE IN SOME PARTS OFTHE WORLD, POWER FAILURES DO

OCCUR AND MUST BE CONSIDEREDWHEN DESIGNING A PUMPING STATION

For more information and specic pump curves, please see the KPL & KWM data booklet.

M.W.L

S

C

C r o s s

f l o w

V

= 2 f t / s

m a x

Pump bay

V = 2 ft/smax

V = 1 ft/smin

V = 3 ft/smax

To avoidsedimentation

Inlet channel

0

15

30

40

NPSH

[ ft ]

ft



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WL MAX H

HWL MIN

H eff H teo

H teoH eff

3.2.8 Trash racks and screens

Partially clogged trash rags or screens can result invery uneven ow patterns and head increases.

Especially at low water levels, a screen clogged by

sediments, oatation layer etc. can result in a con-siderable pressure drop over the screen, reducingthe water level at the pumps. This can contributeto vortices and cavitation in the pumps.

Reduce dead zonesOne way of preventing clogged rags and screens isfrequent inspection and cleaning. However, mini-mizing scraper travel by reducing the size of thedead zones in the screen design can also reducethe problem signicantly.

Screen supportScreens should be divided into several verticalpanels and supported by vertical piers; they shouldnever be supported horizontally, as this may create

velocity jets and severe instability near the pump.

A general guideline is that a screen exit should beplaced a minimum of six bell diameters from thepumps. Observing these guidelines will maximisethe ow channel, thereby eliminating potentialhead increases and making it easy to clean andmaintain the screens.

3.2.9 Handling sludgeDuring dry seasons, water levels recede. When thishappens, the sludge in the remaining water settles inthe sump and the problem is escalated by slow inow.

Sludge settlementIn this situation, additional sludge builds up in thesump and eventually the water evaporates.

The end result may be that the impeller is buried insilt when the pump needs to start.

Install a sludge pumpTo keep the sump clean at all times, it is recommend-ed to install a small sludge pump in a separate, smallpump sump within the main sump. This sludge pumpis used to empty the main sump in periods with lessor no inow to the main sump.

AVOID DEAD ZONES AND OBSTACLES WHERE

SEDIMENTS AND RAGS CAN BUILD UP. ESPECIALLY AT THE BOTTOM OF THESCREENS, FREE PASSAGE IS CRUCIAL

SCREENS ARE MADE FROM VERTICALPANELS, SUPPORTED BY VERTICAL PIERS

NEVER HORIZONTAL PIERS



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3.3 Pump selection

Grundfos provides a full range of pump solutionsfor virtually any purpose. Although, the solutionsare versatile and exible and easy to place in awide range of different installations, selecting theright solution requires access to the conditionsand relevant data.

With the right data available, we c an optimize theoptimal pump solution according to your exact

demands and specic installation.

3.3.1 Axial ow propeller pump or mixed owpump?With a motor range from 20 -1,300 hp, bothGrundfos KPL and Grundfos KWM solutions aredesigned for high-volume water handling.

KPL: Axial ow propeller pumpKWM: Mixed ow pump

RULE OF THUMB:HEAD BELOW 30 ft => KPL AXIAL FLOW PROPELLER PUMPHEAD ABOVE 30 ft => KWM MIXED FLOW PUMP

KPLAxial ow propeller pump, max ow 185,000 gpm, max head: 30 ft.

KWM

Mixed ow pump, max ow 150,000 gpm, max head: 164 ft.Ft M

Ft M

100

26.421.115.913.210.67.95.32.62.10

0

10

13

16

23

33

49

66

98 30

20

15

10

7

5

4

3

807060504030201080

98

66

49

33

23

16

13

10

0

0 21.1 26.4 31.7 42.3 52.3 58.1 68.7 79.3 95.11 95.7

4003603002600 80 100 120 160 200 220

30

20

15

10

7

5

4

3

M³/MIN

US GPMº Ø 10³

M³/MIN

US GPMº Ø 10³

1000KWM

1600KWM1800KWM

1200KWM

1300KWM

1400KWM

500KWM 600KWM 700KWM 800KWM 900KWM

1000KWM

TO REDUCECABLE SIZEYOU COULDCONSIDER A

HIGH VOLTAGEMOTOR.

GRUNDFOSSUPPLIES

MOTORS FROM220 6,600

VOLT

1500 2000 3000 5000 6000 8000 10000 15000 20000 30000 50000 60000 80000 100000 150000Q [US GPM]

4

5

6

7

8

10

15

20

25

30

[ft]H

350400 500 600 700 800 10001 00 0 2 00 0 3 00 0 4 00 0 5 00 0 6 00 0 80 00 1 00 0010000 20000 Q [m³/h]

2

3

4

5

6

7

8

9

1010

] KPL60 Hz



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3.3.3 Pump selection/determinecolumn diameterWhen Q and H have been estab-lished, use the pump curve belowto select the right pump. Select apump with best efficiency point asclose to the nominal duty point aspossible.

How to select a pump• Select a pump based on the

required duty point, operatingrange and safety range.• Use the curve charts in the KPL

& KWM data booklet.• Select pump hydraulics rst and

motor size afterwards.

Example of how to choose:1. Duty point (H = 22 ft and 38,000

US gpm), specied by customer.2. Operating range (33,000 - 39,000

US gpm), specied by customer.3. Q-H curve is obtained at a

propeller angle of 19°.4. P2 at duty point 265 hp.5. P2max in operating range 295 hp

(at a ow of 33,000 US gpm).

Example of how to choose motor size.6. Calculate motor size and select model: Pmotor = P2max * 1.15 (15 % safety margin,

specied by customer) Pmotor = 295 * 1.15 = 340 hp Pmotor ≤ rated motor Rated motor above P motor 340 hp

Selected model: KPL. 40.355.10.T.60.19.A.

7. NPSHA (available) = 40 ft, speciedby customer.NPSHR (required) = 35 ft ( worst casefor operating range).

NPSHA > NPSHR + 2 ft. (accepted)

Depth of the structureConsidering the depth of the pumping station atthe design phase is vital, as smaller pumps canpump to a lower level than larger pumps. Conse-quently, smaller pumps can reduce the requireddepth of the pumping station.

High ow ensures self-cleaning and vice versaAny pumping station design should consider thebenets of self-cleaning. By ensuring high ow/a sufficient water velocity the design will preventsedimentation and the need for regular cleaning. If operation varies much (e.g. with the seasons),dividing the forebay and pump bays into twohalves should be considered. Thereby, you use onlyone half of the station in low-ow seasons.

The dividing walls with an overow gate allowsthe water to ow from one half to the other inhigh-ow seasons and in c ase of emergency.

Flow below 25,000 gpm => 3 pump installationFlow below 210,000 gpm => 4 pump installationFlow above 210,000 gpm => 5-10 pump installation

RULE OFTHUMB:

3.3.2 Number of pumpsSelecting the right pumps and the rightquantity of pumps depends on the loadprole: Q/H/time. In short, the ideal solutioncombination is where the individual pumpoperates as long as possible close to bestefficiency point.

A minimum of two pumps are required:one duty and one stand-by pump. However,by installing more, but smaller pumps you

gain a more reliable and easier controllablesolution.

A sufficient watervelocity enables self-

cleaning design. SELECT THE PUMPSAND THE NUMBER

OF PUMPS BASED ONLOAD PROFILE AND

HIGHEST EFFICIENCY

P u m p i n g s t a

t i o n

d i s c h a r g e

[ % o

f m a x

f l o w

]

Pumping station discharge duration [% of time]

0

10

20

20 40 60 80 1000

30

40

50

60

70

80

90

100



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3.3.4 Minimum submergence (S)Finding the right minimum submergence of a pump is a vital designchoice, as it denes the lowest point of the pumping station and there-fore also a major part of the construction costs.

The Minimum Water Level (MWL) in a pumping station is usuallydened by external conditions, including the level of the incoming pipeor culvert, or the NPSH requirements of the pump.

For NPSH requirements, see 3.2.4 or the KPL & KWM Pump data booklet.

The submergence of the intakeTypically, the submergence of an intake should be large enough toprevent air entraining vortices, swirling ow, and the inuence ofsurface waves. This is possible in a conservative hydraulic design with a

deeply submerged intake,although more costly thana design in which the mini-mum submergence is only just adequate.

Minimum Water Level (MWL) = Clearance (C) + Submergence (S).

The clearance C = 0,5 x Column Diameter (D)

The minimum submergence is dictated by the level to avoidfree surface vortices.

Determine the ow at minimum water level MWL. and lookup the minimum submergence from the following curvesfrom ANSI/HI:

As a fast guide the following table can be used forreference:

All dimensions in inches.Remember to check the NPSH, please refer to 3.2.5.

Minimum submergence at ow up to 22,000 gpm:

Minimum submergence at ow above 22,000 gpm:M.W.L

S

C

S =

B e

l l S u

b m e r g e n c e ,

f t

Q = Flow, gpm.

8

5

11

15

18

21

3170002850002540002220001900001590001270009500063000320000

.

.

NominalColumn

Diameter

Min.Clearance

Min.submergence

Min.Water Level

D C S M.W.L

FLOOD PUMPING STATIONS 3

DESIGNING A FLOOD CONTROL PUMPING STATION 41STORM WATER PUMPING STATION DESIGN GUIDE


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FSI calculationIn the following calculation we have used a safety margin of 2 ft including∆HFSI:

NPSHR ≤ NPSHA = 31 + Smin [ft]

The USACE Formed Suction Intake Type 10 allows a minimum submergenceof 0.94*D.

To get the full benet of this optimized design, you need to select a pumpthat, in the full operating range, has a NPSH R equal to or lower than 31 ft + D.

Alternatively, the minimum water level must be increased.

This table shows themaximum allowedNPSHR if the minimumsubmergence is D:

Example:

If you select a pump for a D = 40 incolumn pipe, you can allow a minimumwater level MWL = 5 ft if your pump has aNPSH required below 34.3 ft in the entireoperating range.

If this is not the case, the minimum waterlevel has to be increased.

This example is based on safety margin +∆HFSI = 2 ft.

Formed Suction Intake (FSI)The minimum water level can be optimized by using theFormed Suction Intake Type 10, designed by the US ArmyCorps of Engineers (USACE).

This, however, increases the demand for NPSH available vs.NPSH required:

NPSHR + safety margin ≤ NPSHA

NPSHR ≤ 33 + Smin - ∆HFSI

– safety margin [ft]

∆HFSI is the friction loss through the FSI, which is depen-dent on design, material, surface structure etc.

Safety marginA safety margin of 2 ft is often recommended.However, the real margin always relies on the individualconditions and has to be assessed in each case.

M.W.L

S=D

C=0.5D

NominalColumn Diameter

Min.Clearance

Min.submergence

Min.Water Level

Max.NPSH required

at min. owD C S M.W.L NPSHreq

[inch] [inch] [inch] [inch] [ft] . . . . . . . . . . .

0

15

30

40

NPSH

[ ft ]



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3.3.5 Turbulence Optimiser ™With an instant change in diameter, turbulencewill occur, resulting in loss of energy.

For column installed pumps thishappens between the pump volute and thecolumn itself.

Reducing turbulenceThe Grundfos Turbulence Optimiser ™ is a rubber diffuser mounted onthe perimeter of the pump volute. The shape of the diffuser is optimizedto reduce turbulence between the volute of the pump and the columnpipe in which the pump is installed.

1-2% energy reductionThe idea is relatively simple; however theeffect is outstanding.

When the pump is running, the TurbulenceOptimiser™ expands and adapts perfectlyto the pipe. This creates a turbulence-freeow and reduces energy losses. In fact,the Turbulence Optimiser ™alone reducesenergy consumption by 1-2%.

3.3.6 Sensors in the pumps

Sensors help alleviate main risksWhen pumps are submerged, there is a greaterrisk of water entering the motor through the cablegland and shaft seal.

For that reason, most manufacturers incorporatean oil chamber with double sealing and also t arange of sensors to protect the pumps – often farmore than in smaller pumps.Typical sensors in large pumps include:

• Bearing temperature sensors (lower and/orupper)

• Motor temperature sensors

• Water-in-oil sensors monitoring the conditionsof the shaft seal

• Terminal box moisture sensors• Vibration sensor• Winding isolation resistance

Monitoring changes in valuesIn addition to the above pump sensor, most ap-plications also have a sensor to keep an eye onpower consumption, voltage, operating hours, etc.Often, keeping an eye on changes in values is moreimportant than responding to absolute values.

During the commissioning stage, it will often bebenecial to experiment with different referencevalues to ascertain when action may be called for.

Leakage sensor terminal box

Bearing temp.

Leakage sensor Water in oilsensor

Temperature sensor for protection of motor

WithoutTurbulenceOptimiser ™:turbulence andloss of energy.

With TurbulenceOptimiser ™: even ow and efficientoperation.



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3.4 Dimensioning the pumping station

Grundfos has more than 30 years of experiencewith pumping station design. We know yourbusiness and what it takes to design a pumpingstation that will serve as a reliable guard againstooding – or minimize the consequences whenit happens.

The design guidelines in the following are basedon the recommendations of the American NationalStandards Institute (ANSI) and The HydraulicInstitute.

3.4.1 Terminology and conventions

InletAn inlet directs water to the pumping station froma supply source such as a culvert, canal or river.Usually, the inlet has a control structure such as aweir or a gate

ForebayThe forebay serves to create a uniform and steadyow to the pump bays. The design of the forebaydepends on the water approach to the pump-ing station commonly encountered as parallelwith the sump centerline, the preferred layout, orperpendicular to the sump centerline. To secure asteady inow to each module, it is essential tofollow the design guidelines presented here.

Pump bayThe pumps are located in the pump bay. Once thewater ows through the pumps bay and reachesthe pump inlet, it must be uniform and withoutswirls and entrained air.

Pump bay

Forebay

Inlet area



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3.4.2 Different station layoutsD

min. D min. 4D D

max.20

max.10

2 D

FRONT INFLOWThe inlet must be placed sym-metrically to the pumps if waterapproaches the station parallel tothe sump centerline. If the inletwidth is smaller than the width ofthe pump bays, the forebay shoulddiverge symmetrically.

The total angle of divergenceshould not exceed 20° for opensump intake designs or 40° forformed intake designs. The bottomslope in the forebay should not bemore than 10°.

If these limits cannot be met, de-vices to manage the ow directioncan improve the ow distribution.

Using model tests of these or morecomplex layouts could suggest theoptimal design.

AdvantagesBalanced inow to the individualpump bays.

ChallengesSize, and achieving enough watervelocity to prevent sedimentation.

SIDE INFLOWAn overow-underow weir canhelp redistribute the ow if theinow is perpendicular to theaxis of the pump bays. However, asubstantial head loss at the weiris required to remove much of thekinetic energy from the incomingow.

Baffle systems may be used toredirect the ow, but their shape,position, and orientation must bedetermined in model tests.

The distance between the weir orbaffles and the pump bays must besufficient to prevent swirls and en-trained air to reach the pump inlet.

AdvantagesCompact design

ChallengesUnbalanced inow to the individu-al pump bays.

3.4.3 Pump bay design

Column-installed pumps in a sump are highvolume pumps, making them sensitive to suctionchamber conditions. Therefore, great care mustbe taken to ensure safe and long-lasting pumpoperation.

As we have touched upon earlier, the main designrequirement for a sump design is to provide opti-mal inlet conditions for the pumps.

The basicsThe ow being delivered to the pump units shouldbe uniform, steady, and free of swirls or entrainedair.

The dividing walls – and the positioning of thepumps – must be designed in a way that avoidssurface vortices, air ingestion and entrainment,and turbulence.


P b d i i i Th i l f f hi i k idOpen sump intake


1.29d


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Splitters and dividersAccording to the ANSI standard 9.8-1998, the opensump intake design includes devices such as split-ters and divider plates that alleviate the effects ofminor asymmetries in the approaching ow.

2. Formed suction intakeThis design is least sensitive to disturbances of theapproaching ow that can result from diverging orturning the ow in the forebay, or from single pumpoperation at partial load.

Formed suction intake designAccording to the US Army corps of engineers (EM1110-2-3105, Aug. 1994.), the FSI design can beconstructed in either concrete or steel. The intakereduces disturbances and swirl in the approachingow. The inclined front wall is designed to preventstagnation of the surface ow.

Pump bay design variations

1. Open sump intakeThis design is sensitive to non-uniform ow, as it requiresa longer forebay and longer dividing walls between theindividual pump bays than the formed suction intake designinstallations. Furthermore, the design is sensitive to owdisturbances such as columns and beams of the civil struc-ture of the pumping station.

The geometrical features of this intake providefor smooth acceleration and turning as the owenters the pump. The minimum submergenceshould not be less than the column diameter.

This design is recommended for stations withmultiple pumps with various operating condi-tions

FSI in concrete

FSI in steel

p pdesign

GRUNDFOS RECOMMENDSUSING OF OUR PATENTED

ANTI-CAVITATION CONE , ACC,AS A FLOOR SPLITTER.

R0.08d

3.30d

1.45d

0.78d

1.06d

D

1.08d

D

2 . 3

1 d

1 . 2

4 d

1 . 2

8 d

1 . 0

6 d

0 . 8

8 d

0 . 4

9 d

0 . 1

6 d


3 4 4 Pumping station dimensions

D



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5150

E

G

K

H

X

F C

W

D

E

3.4.4 Pumping station dimensions

Open sump design: Formed suction intake (FSI),concrete:

D

E=0.5DD

X=5D

D

E

C

S

Min. Water Level (MWL)

W

Nominalcolumn diameter

Min.Clearance

Min.submergence*

Min.water level*

Pumpbay width

Pumpbay length Fillet

D C S M.W.L W X E

All dimensions in inches. * for the exact values of S and MWL, please refer to 3.3.4

Nominalcolumn diameter Clearance

Formed Suction IntakeFSI

Pumpbay width

Pumpbay length Fillet

Floorsplitter

D C H G F W X E K

All dimensions in inches. Remember to check NPSH


Formed suction intake FSI, steel: M 3.5 Duty strategy - reducing the minimum water level



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, :

USACEtype 10.

D

N

L

C

W

F

M

P T

M.W.L

S=D

0.5D

3.5 Duty strategy reducing the minimum water level

From an operational perspective, any water utilityinstallation presents a balance. And sometimesthis balance is a compromise between initial cost(CAPEX), and operation cost (OPEX).

Reducing CAPEXCAPEX can be reduced by selecting pumps that areoptimized as regards size and duty strategy. In thatway you can construct a building that is smallerand not so deep in the ground, i.e. less excavation,less concrete, less cost.

Designing an oversized pumping station may bea reliable security against ood situations, but anexpensive and energy inefficient solution.

Reducing OPEXOPEX can be reduced by considering the loadduration prole of the pumping station and select-ing pumps that in groups can cover the entireoperation range as close to best efficiency point aspossible.

Both objectives, reducing CAPEX and OPEX, canbe met by grouping the pumps in such a way thatthe normal operation area is covered by the mainpumps and then have smaller pumps to pump tothe lowest level.

Nominalcolumn diameter Formed Suction Intake (FSI) steel version

D C F L M N P T W

All dimensions in inches. Remember to check NPSH

P u m p i n g s t a t

i o n

d i s c

h a r g e

[ % o

f m a x

f l o w

]

Pumping station discharge duration [% of time]

0

10

20

20 40 60 80 1000

30

40

50

60

70

80

90

100


3.5.1 Grundfos dedicated controls 3.5.2 Communication modules and SCADATwo-chamber solution Often, the nal pumping station design ends up



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Monitoring and controlFlood control pumps can be a big investment. Inaddition, service and repair can be relatively costly.

Despite optimal system design and high qualitypumps, wear is inevitable – as is the risk of failure.However, monitoring the condition of pumps willlower the total life cycle cost of the ood controlapplication.

Proper monitoring and control will:

• Protect expensive equipment• Help ensure optimum station operation• Reduce energy consumption• Help avoid over ow – and report any incident• Optimize service personnel schedules for pre -

ventive maintenance• Meet demand for more accurate reporting, (e.g.

to comply with stricter environmental legisla-tion)

The changes in the pump conditions describedabove and the easy commissioning are the reasonsfor introducing performance on-demand control inDedicated Controls from Grundfos.

implementationFor complete control of pump systems, theGrundfos eldbus concept is the right solution.The Communication Interface Module (CIM) andthe Communication Interface Unit (CIU) enabledata communication via open and interoperablenetworks and easy integration into SCADA systems.

Connecting Grundfos products to standard eld-bus networks offers substantial benets:

• Complete process control• One concept for Grundfos products• Modular design – prepared for future needs• Based on standard functional pro les• 24-240 VAC/DC power supply in CIU modules• Simple con guration and easy to install• Open communication standards

Your Grundfos CIU/CIM communication interfacesolution can be connected to any SCADA, PLC orBuilding Management System for communicationusing the applicable open protocols for wired andwireless communication.

Flood control pumping stations are often designedto operate under high peak ows in extreme oodsituations. However, most of the year the ow isconsiderably lower.

being quite unsuited for both scenarios.The challenge is that if you optimize your pumpingstation to the water velocities at pe ak ow, youwill most likely have stagnating zones at lowerow, which probably is most of the year.

To overcome this challenge, the station can bedivided into two chambers:• Chamber 1: for low-season operation• Chamber 1+2: for high-season and peak- ow

situations.

The wall between the two chambers of the sta-tion must have a lower section or adjustable weirthat allows the water to ow over into the secondchamber in extreme ood situations.

Pump groupsPump groups enables the user to group two sets of pumps.An example could be to run with two small pumps 80 % of the time (typical load prole) and then in case of heavy raingroup 2 will start.

Group 1Group 2


3.5.4 Motor Protection (MP204)3.5.3 Grundfos Remote Management (GRM) mal, and a xed low fee covers data traffic, hosting



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Protect your pumps against external threatsThe MP 204 protects pump motors against under volt-age, over voltage and other variations in power supply.So even if your external power supply is not entirelysteady, your pump will continue its steady per formance.Your pump motors will also be protected against theoverheating that accompanies such variations andreduces pump lifetime.

Phase errors are a frequent cause of problems forpumps of this type. After you set the relevant phase(1 or 3) during set-up, the learning function of theMP 204 registers the correct phase and reacts if thingsare not right.

The MP 204 also monitors pump power consumption.As reduced power consumption is a strong indicationthat the pump is about to run dry, the MP 204 will im-mediately stop the pump if the power consumptiondrops below 60%.

Maximum uptime is ensured, preventing interruptionsin boosting performance. All this in a unit that can beset up for operation in just 2 minutes.

Grundfos Remote Management (GRM) is a costeffective and straightforward way to monitor andmanage pump installations in a water supply andwastewater infrastructure. It reduces the need foronsite inspections, and in the event of an alarm orwarning, the relevant people are notied directly.

Connecting pumps and peopleGrundfos Remote Management offers you acomplete overview of your pumping systems andlets you be online with your pumps on a securenetwork hosted by Grundfos. You can monitor en-ergy consumption, share documentation, manageservice and maintenance, and maintain a exibleon-call schedule.

As opposed to traditional SCADA systems, GRM isideal for everyone who does not require remoteprocess automation. The initial investment is mini-

costs and system support, including back-up of alldata.

Grundfos Remote Management offers many ad-vantages for managing your critical installations:

Wastewater and ood pumping stationsMonitor standard wastewater pumps, sensorsand controllers of any make and model, includingautomatic reports of operational data.

Water treatment plantsMonitor ow and pressure sensors, tank levels,pumps and security alarms, including automaticreports of power consumption and operationaldata.

Mines and construction sitesReceive alarms from dewatering pumps immediate-ly in the critical event of breakdown or malfunction.

Receive

CIU27

Monitor system

Manage system

Optimiseand report

Pumpsand controls


3.6 Other considerations for the construction3.5.5 Variable frequency drives (CUE) A Grundfos dedicated controller will automaticallyspeed p the p mps to r n a sh c cle or a back



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3.6.1 Support beams and columns for the building

If horizontal beams cannot be avoided, it is impor-tant to consider the normal water level and placethe beams above this.

Prevent the bull whip effectEven narrow submerged beams can c ause consid-erable waves in the pump bay, also known as “thebull whip effect”.

CFD analysis is recommendedWhen placing columns to support the structure,consider the shadow areas they create and intro-duce llets where appropriate.

The llets prevent stagnation regions and sedi-mentation. If possible, such stagnation regionsshould be lled with concrete before operationcommences.

Need assistance?For the best results, feel free to contact our expertsat the Grundfos Water Utility Competence Centersduring your planning stages.

We can assist with everything you needwithin pumping station design, pump selec-tion, future requirements, and the total LifeCycle Costs.

The Grundfos Water Utility CompetenceCenters are located in Copenhagen andAurora, IL.

For more information, please visit:www.grundfos.com/ood-control

Grundfos CUE is a series of variable frequencydrives designed for speed control of a wide rangeof Grundfos pumps. The CUE contains the samecontrol functionality as the Grundfos E-pumps.

Reasons for employing automatic frequency con-trol can both be related to the functionality of theapplication and for saving energy.

For example, automatic frequency control is usedin pump applications where the ow is matchedeither to volume or pressure. The pump adjustsits revolutions to a given set point via a regulatingloop. Adjusting the ow or pressure to the actualdemand reduces power consumption.

Energy vs. reliabilityReducing the power consumption is of courserecommended, but never without considering thevelocity.

Finding just the right balance is optimal, as highspeed will remove sedimentationin the column, but increase en-ergy cost. And low speed reducesenergy costs, but increases the

concentration of solids in thecolumn. This makes the waterheavier and causes the motor totrip on overload.

Flush cycleThe problem of sedimentationand a high concentration of solidsin the water can be solved by anintelligent controller.

speed up the pumps to run a ush cycle, or a backush function to prevent these common problems.

3.5.6 Soft starters

Soft-start eliminates the start-up power surgeassociated with conventional pumps, imposingminimal demand on inverters and generators.

IN THE COLUMN PIPE

IF VELOCITY IS TOO HIGH↓

PRESSURE LOSS ENERGY

IF VELOCITY IS TOO LOW↓

SEDIMENTATION OR HIGHCONCENTRATION OF SOLIDS

Use of soft starters andfrequency drives is often recommended

in order to reduce the load on the

power supply or for adapting to aspecic ow.When using speed control it is important

to consider the resonant frequency ofthe pump and the system in order to

avoid vibrations that can transfer to otherparts of the structure or system.

The ramp time must be adjusted to tthe system.

Horisontal support beam

4.1 Computational Fluid Dynamics(CFD)

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The previous sections of this design guide provide guidelines onhow to design and dimension a ood pumping station. To verify andoptimize the design, as well as identifying areas that need specialattention, CFD or scale model testing is recommended.

Model testing and Computational Fluid Dynamics (CFD) offerimportant information to support vital design decisions. And bothmethods, regardless of preference, will resolve many complex issuesand prevent ow problems before construction begins.

(CFD)

Computational Fluid Dynamics (CFD) simulation has provento be a very useful tool in providing very detailed informationwithin a wide range of areas at a very low cost.

When designing a pumping station, Grundfos specialists canapply CFD simulations to depict accurately uid ows andpressure graphically at any location in the system. This meansthat we are able to simulate and discover ow problems in thesimulation and correct them before construction begins.

Provides design alternativesCFD simulation enables the stakeholders to get a qualitativeand quantitative understanding of p umping station hydraulicsand offers good comparisons between various design alterna-tives.

CFD simulation thus enables everyone involved in a project tomake informed decisions before carrying out the actual infra-structure investments. This makes it possible to evaluate, adjustand eliminate potential risk.

Advanced ooding simulationsGrundfos has been using advanced CFD simulation in manyprojects all over the world, including ood control projects.

Ensuring that ood events can be controlled often requirescareful planning. Using advanced CFD simulations during thedesign phase, we can tailor pump solutions that can cope withthe heavy demands of moving vast ows of surface or stormwater – and guarantee that they work.

Regardless of your specic requirements, we will be morethan happy to bring our expertise with CFD simulation to yourproject.

4.2 Model testing

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Building an actual model of a pumping stationcan be the appropriate solution in some pumpingstation projects. This is especially the case whenseeking solutions to problems in existing stations.If the cause of a problem is unknown, building amodel of the pumping station can be a cost-effec-tive and very efficient way to determine the sourceof the problem.

Model testing allows designers to test alternativesolutions in a real life model rather than trial anderror at full scale. Therefore, model testing canprovide a tried and tested pumping station designor the perfect remedy to a complex problem.

1. Time: It’s fast

2. Economy:Attractive cost

3. Flexibility:Parameters andgeometry can easilybe adjusted

4. Visual:Accurately uidows and pressurein the system

Why useCFD?

Vector andcontour plot, andstreamline of the

ow eld, show the ow direction and

velocity.

Representations of two model pump units.

Wet well, complete with benching, baffle wall, 500 mminterconnecting level equalization pipe and representationsof two model pumps.

Physicalhydraulic

model testing.

The formation of a submerged side wall vortex.

The average velocity is0.5 ft/s, so it may causesedimentation in the sumpbottom.

On the plane 1 ft above bottom

What is a vortex?A vortex is a region within a uid where

5.1 Types of vorticesVortices are a result of ow, speed and pressure and can be formed from

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VORTEX AND HOW TO

PREVENT IT

the ow is mostly a spinning motion aboutan imaginary axis, straight or curved. Thatmotion pattern is called a vortical ow orvortex.

How do they form?Vortices form spontaneously in stirred uids,and are a major component of turbulentow. In the absence of external forces,viscous friction within the uid tends to or-

ganise the ow into a collection of so-calledirrotational vortices.

Vortex explainedWithin such a vortex, the uid’s velocityis greatest next to the imaginary axis anddecreases in inverse proportional distancefrom it. The vorticity (the curl of the uid’svelocity) is very high in a core region sur-rounding the axis and nearly zero in therest of the vortex; while the pressure dropssharply as one approaches that region.

Vortices in pumping stationsVortices in pumping station should beavoided or minimized as they can cause air

entrancement in the pump and cavitation.

the surface when the water level is too low – but can also be formedsubmerged from the back or side wall or from the oor.

Here’s a quick overview of the most common types of “free surfacevortices”:

1. Surface swirl

5. Vortex pulling air bubbles

3. Dye core to intake:coherent swirl

4. Vortex pulling oating trashbut not air

2. Surface dimple

6. Full air core to intake

5.2.2 Submerged vortices

P bl

VORTEX – AND HOW TO PREVENT IT 67 5

5.2 How to prevent vortices

h f ll ll d f h f d h h



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5.2.1 Sub-surface vortices:

Excessive swirl around the pump tube

Problem:In some cases, it can be impossible toprovide adequate submergence and somevortexing or swirl may occur and causeundesirable features of the ow. Thisincludes, excessive swirl around the pumptube with air-entraining surface vorticesand with submerged vortices.

SolutionSwirl around the pump tube is usuallycaused by an asymmetrical velocity dis-tribution in the approach ow. Improvingthe symmetry subdivision of the inlet ow

with dividing walls, and the introductionof training walls, baffles or varied owresistance can in most cases reduce thisproblem. Alternatively, reducing the ow velocity byincreasing the water depth in the sumpwill also minimize the problems of anasymmetrical approach.

Problem:Small asymmetries of ow

Solution:Inserting splitter plates between the pump tube andthe back wall of the sump and underneath the pumpon the oor can remove relatively small asymmetriesof ow. The plates block the swirl around the tubeand prevent formation of wall vortices.

Problem:Submerged vortices are often difficult to detect fromabove the free surface, as they form almost any-where on the solid boundary of the sump.

In fact, only erosion of the propeller blades or roughrunning of the pumps may reveal them.

Solution:Submerged vortices can be eliminated by disturbing

the formation of stagnation points in the ow. Addi-tion of a center cone or a splitter under the pump, orinsertion of llets and benching between adjoiningwall may correct the ow pattern.

In the following, we will introduce some of the most common types of vortices and corrective measures that can prevent themor reduce them to a minimum.

The designs we deal with in this book all have proven to work well in practice. However, replacing old pumps, difficult workingconditions and other unforeseen restraints may in some cases be incompatible with the proper and straightforward designguidelines presented here.

Back wall andfloor splitter plates

Back wall vortex causedby floor splitter only

A: Anti Cavitation Cone ACC

B: Back wall splitter

C: Floor splitter

E: Back wall fillets

F: Side wall fillets

D: Corner fillets

5.2.3 Air-entraining vortices

Problem

VORTEX – AND HOW TO PREVENT IT 69

5.3 Retrotting FSI,Formed Suction Intake

5.5 Reducing surface vortex by retrotting a baffle


D1.5-2DSurface bafflefor vortex suppression


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ProblemAir-entraining vortices develop either in the wake of thepump tube if the inlet velocity is too high or the depth ofow is too small. And if the velocity is too low, they developupstream from the pump.

SolutionAir-entraining vortices can be eliminated by adding extraturbulence to the surface ow. Placing a transverse beamor baffle at a depth equal to about one quar ter of the tube

diameter and at a point about 1.5– 2.0 diameters upstreamof the tube may solve the problem.

If the water levels vary signicantly, a oating beam and aoating raft (plate or grid) upstream of the tube may be abetter choice to eliminate air-entraining vortices.

A possible alternative is the use of an inclined plate.

If you run into c avitation and vortex problems, it ispossible to establish a formed suction intake e.g. bymeans of steel plates:

If you run into cavitation and vortex problems, it is possibleto establish a formed suction intake e.g. by means of steelplates:

5.4 Retrotting back-wall andoor splitters

The rst and most costeffective step to take whenrunning into problems is toinstall a oor splitter, e.g.as a steel plate, shaped andbolted to the pump bay

oor.

PLEASE NOTE THAT THE FLOOR SPLITTERMUST BE A SINGLE VANE, PARALLEL TO THE

PUMP BAY WALL IN THE CENTRELINE OFTHE PUMP, NOT A CROSS.

D / 4

Floating raft or vortexbreaker grid

6.1 Column pipe

Column pipes are typically manufactured locally

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Column pipes are typically manufactured locallyaccording to the design recommendations ofGrundfos, but can of course also be ordered from your local Grundfos Company.

In addition, the seat ring in the bottom of thecolumn pipe can be ordered from Grundfos;please refer to KPL and KWM data booklet.

The seat ring is welded to the column pipe.

6.2 Anti Cavitation Cone (ACC)

The patented Anti Cavitation Cone provides an optimalinlet ow to the pump.

Cavitation – and the noise and vibrations associated withthis harmful process – can be prevented by tting an anti-cavitation cone below the pump just beneath the suctionbowl.

The ACC will prevent:- Cavitation- Pre Swirl- Fluid separation phenomenon- Reduce vortices

Advantages:Reduces noise and vibrations and extends the lifetime ofthe pump.

ACCESSORIES 73

6.5 Cable support system

Cable protection

6.3 Splitters

Back wall and oor splitters can be formed in concrete

6.4 Cable entry

When designing the column pipe including the lid top, we



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Keeping all chains and cables tight in a tube installation isessential. Loose cables and chains that move with the ow willbe subject to wear and damage and eventually result in pre-mature failure. Therefore, a reliable cable suspension system iscrucial.

Cable clamps or xation to the wire or chain should be placedwith a distance suitable for the ow conditions in the columnpipe.

For more information, please refer to the KPL and KWM databooklet.

Cable and chain protection in sea water applicationsRecommendations for column tube installations in sea waterapplications:

• Stainless steel lifting chain, cable protection,and lifting handle

• Zinc anodes on pump• Stainless steel column tube• Epoxy painted steel column tube and pipe to

prevent corrosion - min. 300 m.

Grundfos axial ow pumpshave cable support integratedin the lifting handle.

or manufactured in steel.

The stainless steel version is typically bent or made froma welded stainless steel sheet or a hot dip galvanizedT-bar.

A back wall splitter should end above the maximumwater level.

A oor splitter should pass the column pipe. The totallength of the oor splitter should be 1.5 - 2.0 diametersfrom the back wall.

If you need further information or additional advice,please contact your local Grundfos company.

recommend side-entry of the cables. In comparison with atop entry through the lid, side entry improves handlingduring service.

There are several cable entries available on the market, andcable entries can also be ordered from Grundfos.

ACCESSORIES 75

6.6 Monitoring unit

A complete pre-engineered system

6.7 Formed Suction Intake (FSI)

A USACE type 10 formed suction intake can be constructed in con-

Cablesuspension

system.



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designed to meet future demands andbacked by reliable support.

Depending on motor size, each pumpincorporates sensors for maximum pro-tection at a reasonable cost. Your choiceincludes sensors to monitor windingtemperature, seal condition, moisture,water-in-oil, vibration sensor and bearing

temperature.

In addition, our controllers also monitorinsulation resistance and power consump-tion and offer protection of motors fromoverload to phase sequencing etc.

They are designed to offer complete moni-toring and protection of your pumps forpeace of mind.

The monitoring unit shows:

• Bearing temperature – upper and lower• Stator temperature – 3 phases• Moisture in cable compartment

• Moisture in motor compartment• Customized alarm setting

crete or in steel. For a concrete solution, please see section 3.4.3.

Grundfos can provide the FSI, or the intake can be manufacturedlocally according to our drawings.

Please contact Grundfos for further advice.

Securingthe cable to the

lifting chain.

R0.08d

3.30d

1.45d

1.29d

0.78d

1.06d

D

1.08d

D

2 . 3

1 d

1 . 2

4 d

1 . 2

8 d

1 . 0

6 d

0 . 8

8 d

0 . 4

9 d

0 . 1

6 d

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At Grundfos, we are dedicated to delivering topof the line service. This includes commissioning,repair, and maintenance solutions that preventbreakdowns or rectify problems quickly and pro-fessionally.

We have a service solution for every link in ourcustomers’ value chain. We add a little extra to your businesses and contribute to protectingpeople and infrastructure when disaster strikes.

Operational when you need itMany pumping stations for ood control are notoperational all year round.

Depending on demand and the capacity of thepumping station, some pumps run only a fewtimes a year during the ood season.

To ensure that your pumping station is operatio-

nal and ready to meet immediate demands, werecommend yearly inspections of your pumps andnecessary service checks and maintenance imme-diately prior to the ood season.

For further information about yearly inspections,please refer to the relevant service instructionfrom Grundfos.

GRUNDFOSSERVICE & SOLUTIONS

GRUNDFOS SERVICE & SOLUTIONS 79

What to checkEvery installation works according to its ownspecic conditions. Therefore, it is important thatoperation and maintenance are tailored to the

Combining this with our product expertise, weare able to develop a range of service productofferings that assist and empower our custom-ers in just the right place and at just the right

Service partner networkAll of this, of course, would be of no use to ourcustomers, if our service product offerings werehard to obtain



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Holistic approach to serviceAs with all other systems and applications, notonly the moving parts require inspections and ser-vice. Control of general applications also dependon regular service checks to operate reliably.

Example: If a pit is full of construction material,checking only the alarm function is not sufficient.If the pit itself is not checked, it will probably notoperate when a ood comes.

To prevent unplanned stops, it is important tocheck the application continuously according to awell-dened, specied scheme.

operation and maintenance are tailored to theindividual application and your specic demands.

However, there are a couple of general recommen-dations that apply to a wide range of applications.They include:

• Checking of resistance between phases.• Listening for bearings/noise

• Checking alarms e.g. high level• Checking rotation direction

A regular check of even insignicant componentsis essential and can prove very costly if neglected.An example is the moisture switch alarm. If it doesnot go off when required, the motor will ll withwater and break down. The result is a completerepair of the pump and undesirable downtime.

The natural choice of service providerOur decades of hands-on experience designingand manufacturing pumps have given us vitalknowledge of pump applications, processes, prob-lems, and businesses. We continuously use thisknowledge during the development of new pump

solutions that t changing customer needs.

Our business knowledge is of course also appliedthrough service product offerings. At Grundfos, wehave always cultivated close customer relation-ships and taken an interest in our customers’ pro

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