Holotype of the Blind Cave Eel

Investigating MARs

Finding new ways to manage water responsibly


It may not be the cutest creature. But what the blind cave eel lacks in beauty, it makes up for in scientific value.

“It’s one of the world’s rarest fish – it’s found only in the Pilbara Coast and Barrow Island,” says Shane, who leads the team of 70 water experts in our Iron Ore business in the Pilbara, Western Australia.

“We discovered the eels were living in the aquifer near our Robe Valley iron ore mine, and so we needed to make sure that any future water activities, like dewatering, wouldn’t have an adverse effect on their habitat.”

As we dig deeper to get the iron ore used to make the steel found in everything from bridges to buildings, we often need to mine below the water table. To safely access the ore, as we dig down we need to remove the groundwater that would otherwise enter the pit. This is known as dewatering.

“Our job is to understand whether our dewatering activity could lead to a change in the groundwater level in local aquifers, and whether that would cause any adverse impacts on the aquifer, and on the animals and ecosystems that depend on it – like the blind cave eel.” Shane says.

Our Water Targets

We are among the most transparent in the industry regarding our water stewardship. There are a range of water risks, not just water scarcity, so we have set targets – tailored to the specific challenges at each site – and publicly report on progress against each one. In 2020, we also provided further detail through asset-level disclosures, which show key water risks at each site.

The impacts associated with dewatering and other water supply activities in the Pilbara are a long-term risk for our business. To address this risk, we have set a specific water target for our Pilbara iron ore business: to complete six managed aquifer recharge investigations by 2023.

“Managed aquifer recharge” (MAR) is a process where we add water into aquifers in a controlled way, such as through boreholes. Over the last decade or so, MAR has come on a long way and is emerging as an important method for managing water resources responsibly in the mining industry.

“MAR is a pioneering and still relatively new process and it’s the first time that we’ve worked with it at such a scale,” Shane says.

Water taps

A Shared Resource

Water is a vital resource in the Pilbara, and we need to take into account a wide variety of needs.

More

“Water is essential for our operations,” says Shane, “We need to get access to ore when it is below the water table, and we need to keep the water on and make it available to our operations, our processing infrastructure and our camps.

“Water is also hugely significant for many other stakeholders and ecosystems in the Pilbara. We are in a water-scarce area, and although we get episodic rain – like cyclones – less than 2% of our annual rainfall finds its way back to the aquifers.

“So if we were to allow for natural conditions to recharge the systems, it could take many hundreds of years.

“Water also holds great cultural value for the region’s Traditional Owners, and it is important we listen and develop both an understanding of the technical aspects of water but also its spiritual significance. MAR has the potential to help with this, by returning the water we take out back to the aquifer.”

To be successful, MAR requires a thorough understanding of the hydrogeology in the region and finding a way to “recharge” the water in a way that suits.

“Through our first two investigations, we have already learned a lot about how to design and engineer MAR systems.

It’s all about being prepared, so if in future there is any indication our operations could affect groundwater levels, we’ll be able to counteract that by returning water back to the aquifers.”

Closure is a real driver for our MAR investigations too.

“What we are learning now could be used longer term when we are closing mines and need to return the system to how it was pre-mining,” Shane says.

 

Blind Cave Eel, WA Museum

Banner attribution: Holotype of the Blind Cave Eel, Ophisternon candidum © Mark Allen / Australian Museum 2018. Sourced from http://fishesofaustralia.net.au/Home/species/3203. This file is licensed under the Creative Commons Attribution 3.0 Unported license. (Note: We have expanded the black space around the image to suit our website requirements)

Lower image attribution: Blind Cave Eel, WA Museum.