Technical information
SYSTEM CAPACITY
Peak sand transport capacity |
625 m³/hr |
1,000 tonnes/hr |
Nominal sand transport capacity |
500 m³/hr |
800 tonnes/hr |
Average annual capacity |
500,000 m³ |
800,000 tonnes |
Note: Operations are typically carried out at night.
JETTY DETAILS
Length |
450 m |
Distance from the Tweed River's southern breakwater |
250 m |
Deck elevation (Ch. 168–450 m) |
+8 m AHD |
Pile depth (Ch. 360–450 m) |
−23 m AHD |
Pile depth (Ch. 180–350 m) |
−20 m AHD |
Pile spacing |
10 m |
Jet pump depth (Ch. 360–450 m) |
−15 m AHD |
Jet pump depth (Ch. 280–350 m) |
−14 m AHD |
Jet pump depth (Ch. 180–270m) |
−12 m AHD |
Jet pump spacing |
30 m |
No. of jet pumps |
10 |
Maximum number of operational jet pumps at any time |
4 |
Slope of slurry return pipe (flume) |
2.5% |
Structure material |
Steel |
Deck material |
Concrete |
Note:
AHD – Australian Height Datum is approximately equal to mean sea level.
Ch. – Chainage along the length of jetty
PUMP DETAILS
Pump |
Power |
Flow |
Head |
Type |
Location |
---|---|---|---|---|---|
Low pressure pump |
125 kW 146 kW |
655 l/s |
14 m |
KSB Ajax submersible centrifugal pump |
Tweed River |
High pressure pump (1) |
1100 Kw |
540 l/s |
124 m |
Weir Uniglide centrifugal pump |
Control building – ground level |
High pressure pump |
1100 kW |
540 l/s |
124 m |
KSB Ajax centrifugal pump |
Control building – ground level |
Flume dilution pump |
20 kW 30 kW |
111 l/s |
13 m |
KSB Ajax centrifugal pump |
Control building – ground level |
Slurry pumps (2) |
473 kW 630 kW |
395 l/s |
63 m |
KSB Ajax centrifugal pump |
Control building – lower level |
Note: The low-pressure pump supplies clean sea water from the Tweed River to the high-pressure pump and the flume dilution pump. The high-pressure pump drives the jet pumps. Slurry (sand & sea water) is delivered by the jet pumps and flows in the flume to the slurry pit, adjacent to the control building. The slurry pumps are then used to pump the slurry under the Tweed River, delivering sand to one of the outlets.
PIPELINE DETAILS
From |
To |
Length |
Diameter |
Conveyance |
Type |
---|---|---|---|---|---|
Low pressure pump |
Control building |
440 m |
450 mm |
Sea water |
Polyethylene |
High pressure pump |
Jet pumps |
450 m (max.) |
600>500>400 mm |
Sea water |
Steel |
Flume dilution pump |
Flume @ |
390 m |
250 mm |
Sea water |
Steel |
Flume |
Ch. 450 – Ch. 390 |
60 m |
250 mm |
Slurry |
Polyurethane lined steel |
Flume |
Ch. 420 – Ch. 390 |
30 m |
250 mm |
Slurry |
Polyurethane lined steel |
Flume |
Ch. 390 – Slurry Pit |
390 m |
600 mm |
Slurry |
Polyurethane lined steel |
Control building |
Snapper Rocks East |
1,210 m |
400 mm |
Slurry |
Polyurethane lined steel |
Control building |
Duranbah |
1,260 m |
400 mm |
Slurry |
Polyurethane lined steel > Polyethylene |
Control building |
Snapper Rocks West |
2,108 m |
400 mm |
Slurry |
Polyurethane lined steel |
Control building |
Kirra Groyne |
2,635 m |
400 mm |
Slurry |
Polyurethane lined steel > Polyethylene |
SITE CONDITIONS
Wave climate |
Average significant wave height Hs = 1.3 m |
Tides |
Mean High Water Spring = 0.65 m AHD |
Water temperature |
Maximum = 26° C |
Sand properties |
d90 = 580 µm |
Longshore transport |
Annual Average Gross Transport = 800,000 m³/yr |
DESIGN
The principal consultant involved in the design of the permanent bypassing system was Cardno MBK (Qld) Pty Ltd. A number of specialist design consultants were also engaged:
Mechanical Design Services |
K Little Engineering Pty Ltd |
Coastal Engineering Services |
Coastal Engineering Solutions Pty Ltd |
Electrical Design Services |
J & P Richardson Pty Ltd |
Cathodic Protection Services |
Corrosion Protection Services Pty Ltd |
The design philosophy was to provide design solutions which:
- Are the most cost effective in terms of construction and operation
- Address the safety risks associated with construction and operation of the facility
- Minimise any adverse environmental impact of the facility and
- Optimise the quality and performance of the facility.
The design life of the sand bypassing system is 50 years.
The bypassing system was constructed by McConnell Dowell Constructions Pty Ltd. and completed in early 2001.