Van Dyk is leaving to take up a position with an unlisted dewatering business he plans to acquire an equity stake in.

He is to be replaced by Macmahon general manager of surface mining Michael Finnegan.

Finnegan has been with Macmahon since 2014 and has more than 20 years’ experience in the mining industry.

Prior to joining Macmahon he held senior operational management positions with other major mining contracting companies both in Australia and Asia.

Macmahon chairman Jim Walker said van Dyk had been instrumental in steering the company through a major transformation.

He said Finnegan’s strong operational and technical background would be a benefit to Macmahon.

Van Dyk was at the helm of the company when one of its workers was killed and seven others kidnapped in Nigeria.

As a result Macmahon terminated its contract at Calabar in Nigeria, with operations there due to cease on October 28.

The contract was due to end in 2018 but had been underperforming due to ongoing low mining volumes liked to the client’s production plant and high rental and maintenance costs.

Macmahon has not worked out what its closure costs on the project will be but expects to book those in the first half of the 2016-17 financial year.

The company has also been hit by costs at a job at Telfer due to larger than expected start-up costs, difficult operating conditions and additional maintenance rectification costs for client-supplied equipment.

Those losses have been being incurred since February.

Macmahon is negotiating with Newcrest Mining over ways to mitigate those issues.