Presentation on theme: "InfoWorks CS Enables Design of Hybrid Pressure/Gravity Sewer Systems"— Presentation transcript:
1 InfoWorks CS Enables Design of Hybrid Pressure/Gravity Sewer Systems
2 BackgroundInfoWorks CS has been used for the functional design of proposed residential and industrial hybrid sewer systems.Pipeline sizing, pump selection and storage requirements were all determined using InfoWorks CS.The aim of today’s presentation is to show how the dynamic modelling capabilities of InfoWorks were utilised in functional design.
3 Agenda Definition of Hybrid System Advantages of using InfoWorks CS Case Study 1: Yarra Valley Water – Wonga ParkCase Study 2: Barwon Water – Industrial EstateConclusionsQuestions / Discussion
4 What is a Hybrid System ?GRAVITY SEWERPRESSURE SEWER
5 Advantages of Using InfoWorks CS Allows both analysis of pipe-full flow and part-full flow, so that pressure pipes and impacts on gravity systems can be assessed in one model.Integration with existing gravity system models.Data import / export toolsPump controlsReporting tools
6 Case Study 1: Wonga Park Yarra Valley Water Existing residential area currently not sewered.Approximately 500 properties with a mix of gravity connections and pressure pump unitsArea is low-density with lot sizes approximately 4000 sq m
7 Modelling Issues Considered In addition to the usual design criteria the following issues were considered in modelling:Initial starting conditionsHeadloss in property connections and sensitivity analysis considering varying lot control requirementsPeak flows generated from the system upon resumption of power following a prolonged outage
16 Allowance for Headloss in Property Connections Wonga Park has very large lots with steeply sloping topography and potentially long property connection pipes.To improve the efficiency of the model, property connection pipes were not modelled, however the headloss was still allowed for.
17 Hydraulic Grade Line Outlet Property Connection Friction Head Static HeadProperty Connection
18 Static HeadTaken into account by ensuring the pump well levels and pump cut in/cut out levels are accurate
19 Friction HeadAllowed for by subtracting friction loss from pump curve
24 Consideration of Property Control Solution: two modelsPartial Lot control – pump levels and pump curve based on location of existing propertyFull Lot control – pump levels and pump curve based on worst case
31 Summary Random initial tank level created using inflow hydrograph Pump curves and pump levels altered to account for headloss in property connectionsTwo models built to consider different lot control scenariosRTC utilised to model power outage scenario and report on freeboard to spill
32 Case Study 2: Industrial Estate – Barwon Water 64 Properties. Each with own pressure pump discharging to gravity sewer.Two main catchments each discharging to an outfall pump stationGRAVITY SEWER
33 Issues Considered Sizing of gravity pipe System requirements to cater for peak flows following a power outage
34 Pipeline SizingBarwon Water recognised the importance of dynamic modelling in determining pipe sizing given that:Under normal operating conditions only a small number of pumps operate simultaneouslyHowever there are circumstances where pumps can operate simultaneously.Pipelines were sized based on the flows and velocities predicted by InfoWorks CS, considering usual design criteria
40 Power Outage Scenario Differences from Case Study #1 All pumps discharge into gravity sewer, there is no head restriction limiting pump operation at the resumption of power.Discharge rates are potentially higher – potential for inflow volume to exceed tank volume during a prolonged power outage
41 Node Spill ModelWhere the wet well is predicted to fill during a power outage it is important to consider the node spill model adopted for the node representing the pressure pump well.Two applicable options:LostStored
42 LostOnce the node representing the pressure pump well fills any additional flow is lost from the system.
43 StoredOnce the pressure pump well fills any additional flow is stored and is returned to the system as the well empties.
46 Which Spill Model to Adopt ? Requires understanding of:Likely operation of customersRules applied to customersFor example, if customers don’t have additional storage, the lost model would be more appropriate.
47 SummaryBarwon Water recognised the importance of dynamic model in the efficient design of a hybrid system.InfoWorks CS was used to determine peak flows and size pipelines.The different node spill models available in InfoWorks allow the modelling of different operational scenarios following resumption of power.Modelling of the power outage scenario enabled additional storage requirements to be determined.
48 ConclusionsThe following aspects of the functional design of hybrid sewer systems were modelled using InfoWorks:Hydraulic analysis of both part-full flow and pressurised pipes allowing pipeline sizes to be determinedRandomisation of initial starting conditionsVariable lot control scenariosSystem outflows following a power outage and associated storage requirementsConsideration of various system operating scenarios by use of a choice of node spill models.
49 Acknowledgements Yarra Valley Water – Chris Saliba Barwon Water – Mircea Stancu