Fortescue ground water management

Fortescue Metals’s Group’s Cloudbreak mine site has won national recognition and awards with the Australian Water Association for their advanced groundwater management scheme.

With a capacity of 25Gl of water recharged each year the Cloudbreak Managed Aquifer Recharge Scheme is one of the largest and complex managed aquifer recharge schemes in Australia.

The scheme first established in 2008, is an innovative approach to mitigating environmental impacts related to surface discharge and dewatering drawdown while also conserving water resources for future mine water supply. Iron and manganese removal plays an important role in the management of the Cloudbreak Mine site.

The water treatment plant uses a water filtration media technology known as DMI-65, used for treating ground water elevated levels of iron and manganese to meet Australia Drinking Water Standards. DMI-65 as an alternative to costly reverse osmosis (RO) processes.

Fortescue water supervisor Mark Botica says the DMI-65 consistently proves to be effective and efficient.

"The DMI-65 media used in this treatment plant consistently reduces iron and manganese to ultra-low levels. After filtration through the DMI-65, manganese levels went from 0.939mg/L to 0.02mg/l when mixed with our other potable water supply."

The scheme to date has been so successful that it was awarded the National award for Infrastructure Project Innovation at the Ozwater11 conference and also won the Western Australian Water Infrastructure Innovation Award in 2010. The DMI-65 consists of grains of sand that have had proprietary products infused into them. This means that the active ingredients do not form a coating but become homogenous within the grains of sand. The DMI-65 acts as a catalyst in the oxidation reaction causing dissolved manganese and iron to form a solid, insoluble precipitate that is captured by the DMI-65 filter media. The captured iron is released during the filter backwash cycle.

The DMI-65 has been tested in applications for reducing manganese levels in excess of 2ppm down to less than 0.01ppm. Based on Australian experience in the mining and municipal drinking water industries the DMI-65 is expected to have a lifespan of up to ten years of continuous use.