Decmil has been awarded $71 million worth of contracts for Gina Rinehart's Roy Hill iron ore mine.
The two contracts are for the design, civil engineering and construction of rail and port facilities for the miner, as well as the associated infrastructure.
Design has already begun with actual work expected to start in 2014., with onsite delivery subject to the mine obtaining financing.
Decmil described the one as a significant one for the company.
The Roy Hill rail non-process infrastructure buildings and associated services package is a $56.6 million contract for the design and construction of rail terminal buildings including a rolling stock workshop, wheel lathe building, loco washdown, warehouse and lay down areas, as well as other buildings.
The scope of works also includes specialist maintenance equipment, overhead gantry cranes, fuel/lube delivery systems and oily water treatment.
The Roy Hill port non-process infrastructure buildings is a $14.5 million contract for port landside facilities such as belt-splice workshops, storage and workshops areas with overhead cranes and external cold rooms, maintenance and welding bays, and a hydraulic clean room.
The total contract construction and EPC work onsite for the whole Roy Hill mine is expected to exceed $6 billion.
The win is a major one for a contractor as many companies wind down its outsourced work.
Earlier this week BHP took the axe to the workforce at its Peak Downs coal mine, cancelling a $260 million contract with Leightons to cut costs.