CASE STUDY –––––––––––––––––––––––––

Cloudbreak

Reclaim Tunnel Region, WA,

TechSpan®

Owner: Fortescue Metals Consultants: WorleyParsons Project Manager: Team 45, The Pilbara & Infrastructure Project Construction: 2007

Background Challenge

In 2002/2003, many analysts The Team 45 alliance was set up predicted a rise in iron ore prices of to develop the up to 40%, with long-term demand and manage the construction. expected to remain strong on the Engineering consultant and back of east-Asian economic alliance member Worley Parsons growth. Traditionally, BHP and Rio approached The Reinforced Earth

Tinto have had a monopoly on iron Company (RECO) to design and ore mining in the Pilbara but with supply a reclaim tunnel and escape higher iron ore prices came tunnel under the new iron ore prospective new entrants to the stockpile. market. In 2003 Fortescue Mining The design was complex. The was formed to take up the conical shaped iron ore stockpile challenge to become a third major above the tunnels reached some player and embarked on a rapid 55m height above the crown of the development program that as of arch (10m of backfill and 45m of mid 2008 saw it become a $30 very dense iron ore at 2.9 t/m³). billion company. This made the Cloudbreak

Consequently, in mid 2008 TechSpan® arch tunnels some of

Fortescue was on the verge of the most heavily loaded structures completing the construction of its RECO has designed in Australia to open-access port and rail date and one of the most heavily infrastructure, and first mine site – loaded structures RECO has the Cloudbreak Iron Ore Project. undertaken anywhere in the world.

Cloudbreak is located in the north The iron ore is deposited by an of WA, in the Pilbara region, overhead conveyor and moved approximately 120km northwest of around by a Caterpillar D10 dozer

Newman and at the time of writing with a gross vehicle weight of 67 Installation of TechSpan® reclaim tunnel with would be ranked as the most high tonnes. The tunnels had to be a variable vertical alignment of up to 10% profile mining project in the designed for both the live load of grade adding significantly to the design complexity and requiring wider arch units to country. the dozer acting at pad level and ensure longitudinal arch stability.

Mining infrastructure

Left: TechSpan® precast arch unit is placed on the concrete footing.

Above: Inside the conveyor tunnel.

the dead load of a full height TechSpan® arches. Project specifications stockpile and all the potential load A further 77 lineal metres –––––––––––––––––––––––––––– cases associated with it. The extension to be used as the escape System TechSpan® shape of the stockpile will always tunnel was also added in –––––––––––––––––––––––––––– be changing as the ore is September 2007. To complete the Arch Type TSX1& TSX2 reclaimed for export and as more structure and complement RECO’s –––––––––––––––––––––––––––– iron ore is deposited. involvement in the project, a Span 6.95m Consequently several TerraMet® headwall to the tunnel –––––––––––––––––––––––––––– unbalanced load cases were was also supplied in late 2007. Height 4.35m carefully considered by RECO. The –––––––––––––––––––––––––––– unbalanced load cases often Special features/benefits Length 540m control the design and may cause  The TechSpan® arch tunnel –––––––––––––––––––––––––––– the tunnel to fail if the designer was designed to carry Thickness 0.30m does not consider all possible load extremely high dead loads –––––––––––––––––––––––––––– cases. associated with continuously No. Units 375 changing 55m high stockpile. –––––––––––––––––––––––––––– Solution  The precast concrete arch In late 2006 RECO was initially units were manufactured in awarded the first stage of the mine Perth by Georgiou Group reclaim tunnel, which accounted for using two moulds and turned some 315 lineal meters of 6.7m around daily. span arch. This was followed in  The installation of arches was June 2007 with the award of a a rapid and efficient process further 160 lineal metres extension overseen on site by to the original tunnel, this section experienced RECO was on a variable vertical technicians. alignment of up to 10% grade  The arch headwall used adding significantly to the design TerraMet®, RECO’s complexity and requiring wider arch lightweight steel faced units to ensure longitudinal arch retaining wall system, which is stability. This was one of the widely used in the Pilbara, steepest grades undertaken using particularly to ROM dump structures behind crushers.

Reinforced Earth Pty Limited Reinforced Earth Limited Level 4, 20 George Street PO Box 72 734 Hornsby NSW 2077 Australia Papakura Auckland New Zealand Ph +61 2 9910 9910 Ph +64 9 236 3385 Fax +61 2 9910 9999 Fax +64 9 236 3385 www.reco.com.au www.reco.com.au