Gold Fields Ltd. said Thursday it is investing about $65.8 million to deepen its Driefontein and Kloof gold mines in South Africa.

The South Africa-based gold miner said the move will help them access an additional 10.8 million ounces of gold below the current infrastructure of the two mines.

The deepening of the Driefontein mine will produce an additional 8.8 million ounces of reserves and extending its life about 13 years to 2035. Changes to the Kloof site will let the company mine an additional 2 million ounces of reserves and will add incremental gold production from 2011 to 2021, Gold Fields said.

The company will fund the projects internally.