Engineering firm Monadelphous Group has won about $180 million worth of contracts in Western Australia for infrastructure work on behalf of global miner Rio Tinto and US-based energy major Chevron.

“These contracts support our objective of sustainable growth through the expansion of our infrastructure business and they build on our long-term relationships with blue chip customers,” Monadelphous managing director Rob Velletri said in a statement.

Monadelphous will build and install a potable water supply system for Rio Tinto’s Coastal Waters project in the state’s Pilbara region, according to the deals announced on Monday.

The work is expected to start during the March quarter and be completed in the first half of calendar 2013.

Monadelphous has also secured its third pipelines contract for Chevron’s $43 billion Gorgon liquefied natural gas project on Barrow Island, offshore from the Pilbara region.

The contract announced on Monday is for the preparation and construction of seven kilometres of underground pipeline for carbon dioxide injection purposes, as well as five well sites and associated facilities.

Gorgon, one of the world’s largest natural gas projects, will also include Australia’s first large-scale geosequestration project.

Monadelphous said the work for Chevron would commence immediately and was slated for completion in the first quarter of the 2013 calendar year.

Shares in Monadelphous were down 20 cents at $22.40 at 1512 AEDT.