Under the deal, Leighton will take over the majority of Macmahon’s construction projects, associated plant and employees, with the exception of projects nearing completion, including Hope Downs 4, Solomon Rail Spur, the Gladstone LNG project and several other minor projects.

This will give Macmahon a net consideration of about $14 million after transferring employee liabilities associated with personnel moving to Leighton.

However, not all employees will be so lucky as to be guaranteed a transfer to Leighton.

Macmahon said it expected one-off restructuring and redundancy costs of about $12 million.

In terms of equipment, Macmahon will retain about $40 million worth of plant for potential use in its mining business.

Macmahon chief executive Ross Carroll said the sale was an important milestone in the company’s transition into becoming a dedicated mining contractor.

"This is a significant day for the company as we refocus the business on our successful full service mining operations," Carroll said.

"Since winning our first mining contract in 1967, Macmahon's mining operations have continued to grow and I am pleased that we can now focus all our efforts on being a full service mining contractor of choice within the industry.”

Macmahon will continue to participate in the Hong Kong express rail link project and the Trangie Nevertire Irrigation Scheme in New South Wales for the time being as the company said commercial terms could not be agreed with respect to their sale to Leighton.

The sale will be effective on December 31 and subject to shareholder approval at an general meeting expected to be held in February next year.

Shares in Macmahon dropped 4.3% or 1c to 22.5c.