GEELONG MODELLING PROGRAMAND FUTURE UPGRADES

Mircea Stancu 25 June 2010

BARWON WATER

Regional Water Corporation

South west of Melbourne

GEELONG DISTRICT SEWER CATCHMENT

Geelong

GEELONG DISTRICT SEWER CATCHMENT

GEELONG DISTRICT SEWER CATCHMENT

GEELONG DISTRICT SEWER CATCHMENT

POPULATION GROWTH PREDICTION

GREATER GEELONG AREA2045 PREDICTION

New residents: between 88,000 and 142,000

Total ADWFs will increase by between 75ML/day and 100ML/day (over 50% increase)

Increase in ADWF to Black Rock WRP between 69ML/day and 92ML/day (over 50% increase)

GEELONG DISTRICT SEWER CATCHMENT

GEELONG TRUNK NETWORK

Trunk network in Geelong

- Relatively isolated from northern flows

- Relying on two main sewers

- Very difficult to upgrade (going through Geelong CBD

- High impact in case of failure

- Future servicing strategy relying on smart use of interconnections and current capacity.

Flow Retarding Facility

New WRP

GEELONG TRUNK NETWORK

How it works

CURRENT PRACTICE

Current Status Quo

- Extensive use of WSAA code recommendations for smaller divisions- A current MIKE11/MOUSE trunk sewer model mainly used by

consultants- No in-house expertise on model/software package

MONITORING PROGRAM

Location of monitors

Monitoring for:- Level- Flow- EC- Rainfall

Monitoring Program:- Early phase of

implementation- May be enhanced by

temporary monitoring- 3 years long - Main scope is to provide

reliable data for the modelling project

MODELLING PROGRAM SCOPE

MAIN SCOPE- Prove 1 in 5 years compliance- Providing better network behavior understanding- Providing critical information for new Capital Works Expenditure- Providing option analysis tools (best value for money)- Providing information for maintenance purposes (high infiltration areas,

diversion flows, etc.)

ADDITIONAL SCOPE- Confirmation of sewer return ratios- Information regarding effects of water restriction on sewer flows- Confirmation of impact of repairs (e.g. sewer re-lining, de-silting) and

replacements- Better prediction of the impact of new developments- Flow profiles and their impact on sewer mining options- Impact of sewer mining on network- Infiltration level information (including saltwater infiltration)- Horizontal integration with BW’s GIS system

Will attempt to solve main issues we are facing such as:

- How much spare capacity we still have in the pipes

- How the interconnections will work and how the network will respond

- How the new WRP to the north of Geelong will influence the network behavior

- When we will need to upgrade the transport pipe from Geelong to Black Rock

MODELLING RESOURCING AND DELIVERY OPTIONS

Current ideas:DEVELOPMENT: Externally developed, internally maintained

- Provides best combination of risk mitigation and value for expenditure

MODEL TYPE:Detailed network

- Longer setup time of geographical network however far easier to set up parameters and loadings

- Corrected GIS data can be fed back into the GIS system- Less error prone to options analysis and inclusion of new developments

and demands (no bulk catchments)- Provide a good platform for the modelling of other smaller areas for

various purposes (infiltration modelling, sewer mining, flows diversions etc.)

- Easy to improve in the future

MODELLING RESOURCING AND DELIVERY OPTIONS

SUMMARY:

My recommendation is for the model to be:- Detailed network- Externally generated- Internally maintained

MODELLING PROJECT IMPLEMENTATION STEPS

1. Ensure stakeholders agreement and corporate support: Aug-Sept

2. Ask for capabilities statement and/or presentations from major software developers (i.e. write software requirements brief): Sept-Oct

3. Choose software package: Oct-Nov

4. Write consultants brief: Nov

5. Tender process: Nov-Dec

6. Project delivery: Early 2011 with yearly calibrations

7. Maintenance and training: 2011 onwards

MODELLING PROJECT IMPLEMENTATION STEPS

Discussion

MAIN OUTFALL SEWER DUPLICATION

Main Outfall Sewer as a part of the overall network:

MAIN OUTFALL SEWER DUPLICATION

GEELONG DISTRICT SEWER CATCHMENT

MAIN OUTFALL SEWER

Characteristics:

- 10.5 km long

- 1650mm dia

- Strategic asset

- Very shallow slope (1 in 3000)

- Over 30 years old but in acceptable condition

MAIN OUTFALL SEWER AND ITS DUPLICATION

MAIN OUTFALL SEWER

- Close to reaching capacity in wet weather

- We know it will need to be upgraded

- The modelling program will provide better estimates of future flows and upgrade timelines

- Running through major future development hence route needs to be decided before development occurs

- Current capacity: 2000L/s

- Predicted needed capacity (PWWF): 3600L/s

- Will continue to transport all DWFs

Development Boundary

AUGMENTATION OPTIONS

Development Boundary

Same route has been decided

Three options:

1. Identical duplication (1650dia @ 1 in 3000 grade). Price: ~80 mil.

2. Rising main (1100mm dia). Price: ~40 mil.

3. Pressure gravity sewer (1100mm dia @ 1 in 3000). Can be pressurized. Price: ~60mil.

DIFFERENCE IN PUMPED FLOW VOLUMES

Option 2: Rising main Option 3: Pressure Gravity Sewer

WINNING OPTION

NUMBER 3: Pressure gravity sewer

It provides significant advantages and very high flexibility, for a smaller price compared to an exact duplication.

• Questions?