Under the two five-year contracts, Thiess will deliver underground mining services at the Rio Tinto-managed Oyu Tolgoi Mine, as well as provide asset management services for Energy Resources at the Ukhaa Khudag (UHG) Mine.

Since establishing operations in Mongolia in 2007, Thiess has developed strong in-country capability and delivered mining and maintenance solutions across a range of projects nationwide. 

Thiess Executive Chair and CEO Michael Wright said the contracts reflected Thiess’ focus on growing from its core while expanding across services, commodities and geographies. 

"These awards demonstrate the trust our clients place in Thiess and reflect the strength of our long-standing partnerships with Oyu Tolgoi and Energy Resources, as well as the capability of our team.

Our success is built on our global expertise, our local people and our local capability, and we’re proud these contracts will create new career opportunities as our workforce grows.” 

CIMIC Group President and Executive Director Roberto Gallardo said the contracts reinforced the strategic importance of Thiess’ client relationships and natural resources capabilities. 

"Long-term contracts with leading clients are central to Thiess’ strength and to CIMIC’s natural resources strategy, and these awards in Mongolia are a clear example of that in action. 

Mongolia remains a key market for Thiess, and these contracts reinforce our long-term commitment to our clients, communities and the country.” 

Oyu Tolgoi Copper - Underground Mining Services 
At the Oyu Tolgoi Mine, Thiess, through the Thiess-Khishig Arvin Joint Venture (TKAJV), will provide underground mining services, including underground development, ground support installation and block cave infrastructure construction. 

The project will support the continued development of one of the world’s largest copper-gold operations and is expected to create more than 110 new roles over the next few months. The workforce is projected to grow to almost 800 people by the end of the contract term, making it Thiess’ largest underground mining operation globally. 

The award builds on Thiess’ established presence at Oyu Tolgoi, where it has operated since 2016 through the TKAJV.  

Energy Resources - CHPP Asset Management Services 

Under the agreement with Energy Resources, Thiess will provide Coal Handling and Preparation Plant (CHPP) asset management services at the Ukhaa Khudag Mine. 

The scope includes asset management, supply chain management, technical support and planning services to support efficient, reliable operations.  

The award extends Thiess’ long-standing relationship with Energy Resources and reflects a shared commitment to safety, operational excellence and continuous improvement. 

Published Date:2026-10-22