The variation will see Thiess mine additional overburden through until 2020 as per the terms of the contract, after commencing work at Caval Ridge in November 2017.
Thiess will continue to provide mining services for specific components of work including the services required for Caval Ridge Southern Circuit.
CIMIC Group Chief Executive Office Michael Wright said: “This award builds on our relationship with BMA and reinforces Thiess commitment to delivering value for our clients.”
CIMIC Group Executive Mining and Mineral Processing and Thiess Managing Director Douglas Thompson said: “We are proud of this contract. It’s a testament to the team’s track record of performance and focus on delivering a safe and productive operation for our client.