BHP has completed a repair and expansion of the Spence Copper mine tailings dam in Chile.

The tailings dam was waterproofed as it was expanded to hold 2,855 hectares for mining waste. The dam stores waste that remains after the copper ore has been separated from gangue.

Penetron reported in a statement today that it provided the waterproofing system for the dam. The initial tailings dam expansion plan did not include plans for waterproofing, Penetron said. However, several leaks emerged after the concrete had been reinforced.

The company sealed 60 meters of cracks with Penecrete Mortar, a solution that reinforces structurally damaged concrete. Waterproofing material Penetron was applied to nearly 5,000 square meters, while another 10,000 meters cubed was treated with Penetron Admix, which was mixed with the concrete to ensure stability.

BHP built a US$2.46 billion concentrator plant for Spence which can process 95,000 tonnes of material per day. The plant is expected to expand the Spence mine life by 50 years.

First copper sales from Spence are planned for the January quarter.