Australia-headquartered resources company BHP Group on Friday presented an update on the company’s approach to its tailings storage facilities’ (TSF’s) management and to provide information on the number, design and classification of tailings facilities.

BHP said it was establishing a dedicated tailings task force to drive enhanced focus on internal dam management and to support the development of international best practice. It was also investigating new technologies to further mitigate current dam risks and eliminate future risk.

The diversified major embarked on a companywide dam risk review in 2016, following the previous year’s dam failure at its Brazilian mining joint venture (JV) Samarco. The incident at the iron-ore mine killed 19 people and caused major environmental damage.

The release by BHP report also comes as many other mine operators published information about their TSFs on Friday, following a call by the Investor Mining and Tailings Safety Initiative – an investor-led engagement convening institutional investors active in extractive industries – for information on tailings dams to be published by all tailings operators.

A group of 96 institutional investors (representing more than $10.3-trillion assets under management) had written to 683 extractive companies seeking greater disclosure on the management of TSFs, following the catastrophic January 2019 tailings dam failure in Brumadinho, Brazil, which led to the loss of more than 300 lives.  

There is currently no consolidated global public register of TFSs. It has been estimated that there are about 18 000 TFSs worldwide, of which around 3 500 are active. It was owing to the absence of such a register that the investor initiative called for action. 

BHP’s review assessed dam design, construction, operations, emergency response and governance to determine the current level of risk and the adequacy and effectiveness of controls. BHP on Friday reported that the review identified no immediate concerns at any facility regarding dam integrity.

The company confirmed it would focus continually on appropriate engineering design, quality construction, operating discipline and effective governance processes to ensure that risk controls were effectively implemented and maintained. Four-hundred dam risk review actions had been assigned to BHP’s assets, of which 93% were completed by Friday.

BHP explained that the remaining open actions in progress were those with longer lead times.

These review actions (at asset level) included training personnel on emergency preparedness and response, revise dam break analyses, appointed dam engineers for dam stewardship as well as an engineer responsible for dam design.

The review actions at group level included dam safety reviews undertaken across BHP and independent review boards being established across the company; allocating the Resource Engineering Centre of Excellence for global accountability for the technical oversight of dam integrity and governance; assessing technology options to further reduce dam integrity risk; and developing a standard for minimum requirements around dam integrity.

For context, BHP explained in its presentation that there are three broad design types for tailings dams: upstream, downstream and centreline.  Dam designs are informed by the nature of the tailings and environmental conditions, including dam siting, geology, seismicity and climate. 

BHP operates 67 tailings facilities across all its sites, including 12 active sites in Australia and one in Chile. Twenty-nine of the company’s operated facilities are upstream, of which five are active. Other sites are spread across the US and Canada.

At the company’s non-operated JVs there are nine facilities, five of which are upstream, all of which are inactive, across North and South America.

BHP noted ongoing dam operating discipline includes tailings characterisation and deposition, effective water management, monitoring and appropriate consideration of changes, including ore, operating context and climate.

The company further explained common terms used to describe failure mechanisms at tailings facilities. These are overtopping, which is caused by water volumes exceeding the capacity of the dam; structural failure of materials used in dam construction, including from liquefaction and seismicity; foundation failure; surface erosion of the embankment from settlement, or cracking; internal erosion of the embankment; and deficiencies in the choice of design criteria, such as not being meeting engineering requirements.