Alaska regulators monitor backfill leak at mine

Alaska environmental regulators are monitoring a spill of material used to shore up underground workings at the Pogo Mine in the state’s interior.

The Alaska Department of Environmental Regulation says a leak of “paste backfill” was discovered Thursday by workers, who reported the spill. The material is placed underground to form supportive concrete.

Regulators say an estimated 36,000 gallons of the amount spilled was released outside a containment area. Officials say the material’s high viscosity means it likely will not spread beyond the gravel pad where it is contained.

Officials say the responsible party is Sumitomo Metal Mining Pogo LLC, which has launched an investigation to determine the cause of the spill. Pogo was fully purchased by Japanese partner companies – Sumitomo Metal Mining and Sumitomo Corp. – in 2009.