Joint venture partners AngloGold Ashanti (JSE:ANG) (NYSE:AU) and Independence Group (IGO) have approved $79.3 million underground expansion at their Tropicana gold mine in Western Australia.

The project, dubbed the Boston Shaker, is expected to contribute higher-grade mill feed, resulting in an improved gold production profile and enhanced cash flow.

Once the underground portion is operative, Tropicana — located 200km east of Sunrise Dam and 330km east-northeast of Kalgoorlie — will be able to maintain gold production at between 450,000-500,000 ounces annually over the five years to and including the 2023 financial year.

The Boston Shaker extension is expected to contribute an annual average of 100,000 ounces to Tropicana’s production profile from the 2021 financial year.Boston Shaker is expected to contribute around 100,000 ounces a year, with first gold expected during the September 2020 quarter. The feasibility study estimated a capital cost for the project of A$105 million, higher than the $95 million estimated in December.

“Underground mining at Boston Shaker will leverage further value from this high performing operation, achieving pay-back in just over three years,” Ludwig Eybers, AngloGold Ashanti’s Chief Operating Officer International, said in the statement.

The Boston Shaker ore body remains open at depth and the JV partners will continue to test high grade extensions to the mineral resource beneath the Tropicana and Havana pits to assess the opportunity for further underground mining operations, they said.

Macmahon Holdings has been awarded a five-year, $170 million mining services contract for the underground mine. The work adds to the supplier’s existing agreement at Tropicana, which is already the site of the company’s largest mining contract in Australia.

AngloGold, now under the leadership of Kelvin Dushnisky, a Barrick Gold veteran, looks very different from four years ago. The company has become increasingly global, with only about 13% of its output from South Africa after selling mines to stem losses in the country. That’s down from 43% in 2007.

AngloGold’s other mines stretch from Australia to Argentina and Ghana, and the company owns 70% of Tropicana while Independence Group NL holds the