Paper #

Tunneling for Desalination Projects in Australia

Malcolm DixonGHD

Service Line Leader - Tunneling

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Tota

l Ann

ual*

Inflo

w to

Per

th D

ams*

* (G

L)

Annual Total

1911-1974 av (338 GL)

1975 - 1996 av (177 GL)

1997 -2005 av (114 GL)

Regression 1960 to 2005

Notes: - A year is taken as May to April - 2005/06 inflow to 1st November 2006

2006

Impact of Drying Climate – Dam Inflows

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The Desalination Process

FreshWater

SalineWater

Reverse Osmosis

key components of SWRO:• Inlet and outlet• Pre-treatment• Reverse Osmosis• Post-treatment• Water storage• Water transfer• Power supply

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Australian Desalination Projects with Tunnels

Gold Coast Plant (Tugun, 2008)_•135 MLD capacity

Sydney Plant (Kurnell, 2010)•250 MLD capacity

Victorian Plant (Wonthaggi, 2012)•410 MLD capacity

Adelaide Plant (Pt Stanvac, 2011)•300 MLD capacity

Perth 2 Plant (Binningup, 2011)•150 MLD capacity

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Australian ProjectsPlant Capacity Year of

CommissionTotal Capital Cost (AUD$)

Intake/Outlet Diameter (m)

Intake/Outlet Length (m)

No. of Intake/Outlet Risers

Vertical Alignment

Gold Coast (Tugun)

135 ML/day 2008 $943 Million

2.8 m/2.8 m 2.2 km/2.0 km 1/1 Incline

Sydney (Kurnell)

250 ML/day 2010 $1,443 Million

3.4 m/3.4 m 2.5 km/2.5 km 4/2 Decline

Melbourne (Wonthaggi)

410 ML/day 2012 $2,870 Million

4 m/4 m 1.2 km/1.5 km 2/2 Decline

Adelaide (Point Stanvac)

300 ML/day 2011 $1,500 Million

2.8 m/2.8 m 1.5 km/1.2 km 1/6 Decline

Perth 2 (Binningup)

150 ML/day 2011 $738 Million

2.4 m/2.0 m (2 intake tunnels)

0.9 km/0.9 km 2/1 Decline

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GHD and Desalination Tunnels1. Gold Coast – Owner’s Engineer for design and construction phase

2. Sydney – Prepared reference design, carried out majority of geotechnical investigations, client’s technical advisor for design and construction phase and prepared all technical tender documents.

3. Adelaide – Owner’s Engineer and prepared Environmental Impact Statement

4. Perth 2 – Alliance team member for Plant Engineering

5. Melbourne – Prepared environmental effects study, obtained approvals, reference design, Owner’s Engineer for design and construction phase.

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Plant TBM Type Lining Type Intake/Outlet Diameter (m)

Lining Thickness

External Water Pressure (bar)

No. of Segments Reinforcement

Gold Coast (Tugun)

Herrenknecht slurry shield

Precast segments

2.8 m/2.8 m 200 mm 5.7 6 (trapezoidal) 35 kg/m3

(fibres)

Sydney (Kurnell) Herrenknecht double shield

Precast segments

3.4 m/3.4 m 225 mm 5.0 6 (trapezoidal) 35 kg/m3

(fibres)

Melbourne (Wonthaggi)

Herrenknecht slurry shield

Precast segments

4 m/4 m 230 mm 4.2 4 (parallelogram) 2 (trapezoidal)

35 kg/m3

(fibres)

Adelaide (Point Stanvac)

Herrenknecht slurry shield

Precast segments

2.8 m/2.8 m 200 mm 5.5 6 (trapezoidal) 35 kg/m3

(fibres)

Perth 2 (Binningup)

Herrenknecht slury pipejack (AVN)

Pipe jacking 2.4 m/2.0 m (2 intakes)

NA 3.0 NA NA

Tunneling Method

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Geotechnical InvestigationsProject Number of offshore

BoreholesOffshore Geophysics Other Investigations

Gold Coast (Tugun) 8 Seismic reflection Bathymetric profiling

Sydney (Kurnell) 0 Magnetic survey, electrical resistivity 12 on shore CPTs, bathymetric profiling

Melbourne (Wonthaggi) 3 Seismic refraction, gravity survey, magnetic survey

2 exploratory HDD holes, bathymetric profiling

Adelaide (Point Stanvac) 2 Seismic reflection and refraction Bathymetric profiling

Perth 2 (Binningup) 5 unknown Bathymetric profiling

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Twin 3.4 m OD intake/outfall tunnels2.4 km & 2.1 km sized for 170 ML/d

Gold Coast Desalination Plant

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Gold Coast Desalination Plant

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Gold Coast Desalination Plant

TBMs (75 m /week)

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Gold Coast Desalination Plant

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Victorian Desalination Project

Source: Aquasure

Victorian Plant– Offshore Geophysics

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Victorian Plant– Cored HDD Holes

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Victorian Plant– Riser Connections

Jack up Barge - 55 x 32 metres

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Sydney Desalination Plant

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Sydney Desalination Plant

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Sydney Plant – Riser Options

Off-line Connection In-line Connection

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Sydney Plant – Riser Construction

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Adelaide Desalination Plant

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Adelaide Desalination PlantThe jack-up barge:

• weighs 2400 tonnes with cranes;• has four legs, each 45 metres long;• measures about 30 x 35 metres;• includes a helipad so workers can be flown in and out at each shift;• has GPS technology on board to ensure each anchored location is exact;• once jacked into place, can maintain approximately 6 metres air space between the platformand the ocean.

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Adelaide Desalination Plant

2.4 km of bored tunnel in 40 weeks

DN900 outlet riser, 20 m long. Manufactured from glass fibre reinforced plastic (GRP).

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Perth 2 Desalination PlantInnovative Construction:

• dual mode pipe jacking TBM for variable geotechnical conditions;

• orbital welder which provided a 360 HDPE weld around the pipe joints that provides protection against marine growth;

• Project specific jacking pipe design to achieve 100 year design life;

• Wet recovery of TBM and relaunch.

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Perth 2 Desalination Plant