Consulting Engineering & Project Management

THE TAILINGS DAM CHALLENGE

Consulting engineers have a crucial role to play in the planning, construction and oversight of tailings dams. We consider what their exact responsibilities are

By Rodney Weidemann

The collapse of a tailings dam near the historic Jagersfontein Diamond Mine in the Free State in September ended with a flood of mine slurry that caused untold damage – destroying houses and cars and killing and injuring people.

This has raised questions about who should be responsible for tailings dams oversight and, in this article, the role of the consulting engineer in the planning, design and construction of tailings dams.

Michelle Porter-Wright, counsel in Allen & Overy South Africa’s disputes practice, suggests that the design of tailings facilities is a multidisciplinary a air.

“Design depends on the quantity and the individual characteristics of the tailings produced by the mining or industrial operation, as well as the climatic, topographic, geologic, hydro-geologic and geotechnical characteristics of the disposal site.

“It also depends on regulatory requirements related to dam safety and to environmental performance. Ultimately, what may work for one type of tailing product may not work for another type. As such, each situation requires its own design process,” she says.

Chris Campbell, CEO of Consulting Engineers South Africa (CESA), adds that mining developments are multi-faceted and o en highly specialised, as is the area related to the planning, design and construction of tailings dams.

“There are not many specialists in this area, and the ones with the expertise are ageing and heading towards retirement. The advisory role on the siting and planning as well as the design falls within the expertise of these design engineers. They would then be commissioned by the client to supervise the construction of the dam, which should be carried out by a reputable construction company,” he says.

CODE OF PRACTICE

Porter-Wright notes that a consulting engineer’s role in a tailings dam project will be apparent from the construction contract and the relevant code of practice (COP) prepared and implemented by the specific mine to deal with mine residue deposits.

“In respect of the planning, design and construction of a tailings dam, the COP will, at minimum, require a professional engineer – as a function of their general obligation of due skill and care – to undertake certain preparations and certifications.

“For one, they will need to review and certify technical reports dealing with the characteristics of the mine residue – such as physical, chemical and radiological – as well as optimal site selection, design and design rationale, and the work procedures that must be followed in the construction and operation of the tailings dam.”

Furthermore, they must prepare a design that takes into account all phases of the life cycle of a mine, and construct it in a manner that ensures that the measures set out in the COP are adhered to.

Campbell points out that the mining company will appoint a consulting company to provide monitoring and inspection services to ensure that the structure is still intact and that there are no risks of failure. Where maintenance is required, they will recommend that the owner makes provision for appointing a contractor to do such maintenance, which is not done by the consulting engineering company directly.

“This remains a long-term responsibility. However, the problem arises when the mine ownership changes and the new owner may not appoint the same company or any other new service provider to play this role.

“Sometimes the new owner only looks at the assets and not the likely liabilities

FRAGMENTED GOVERNANCE

Mining developments are multi-faceted “ and o en highly specialised, as is the “ area related to the planning, design and construction of tailings dams. – Campbell

of the operations that they have assumed, and tries to avoid the costs that would be related to such monitoring and maintenance responsibilities. This is likely due to a limited understanding of the health and safety risks related to tailings dams,” he says.

Campbell suggests that the long-term safety of such dams remains a highly specialised area. Since the mining company would likely not have the expertise to do this internally, it has an obligation to commission the services of a reputable consulting engineering company to fulfil the inspection, monitoring and advisory role to the mining company.

“This will be necessary for as long as one owns such an operation, as it is not only the mining assets that would have been purchased, but also the liabilities in respect of managing such risks.”

WHO IS RESPONSIBLE?

When it comes to the question of who bears ultimate responsibility for the collapse of a tailings dam, Kalinka Eksteen, senior associate at Allen & Overy SA, suggests that there is a possibility of legal comebacks on the consulting engineer involved.

“While the owner of the mine would likely bear the ultimate responsibility for the collapse, where it appears that it was the conduct of, or failures by, the consulting engineer that caused the collapse, the owner and other a ected parties could seek also to hold the consulting engineer liable for damages and losses sustained as a result,” she states.

“It must be noted that not all damages would be claimable – damages may be limited by the terms of the contract itself, as well as by established legal principles applied by our courts – including whether the damages flow naturally from the breach or are too remote.”

Eksteen believes mines should commit to making public and environmental safety a primary goal in tailings management, as opposed to a secondary consideration.

“The mine and the consulting engineer should not treat the project as a box-ticking exercise, but rather use safety as the guiding principle in the design, construction, operation and closure of tailings facilities. Practically, this would involve using the best available technology and the latest information on tailings facilities.”

Campbell o ers some additional advice: “This is definitely an area of specialised expertise, and many of those experts are getting close to retirement. Therefore, there should be a focused drive to develop future capacity in such areas of specialisation, as there is the real risk that the capacity constraint will, and probably already has, started manifesting itself.”

There are probably newer technology developments that aid in the remote monitoring process, he says. “But nothing beats old-fashioned hands-on onsite inspections by experts to ensure that the risks are adequately identified at an early stage and then so managed.” ■

The standards and legislative provisions specifically governing tailings dams are fragmented and incomplete. At present, tailings dams are governed largely by:

■ SANS10286 (previously known as

SABS0286:1998).

■ COP guidelines. ■ COP dealing with mine residue

deposits.

■ Regulations regarding the

planning and management of residue stockpiles and deposits, published under the National

Environmental Management:

Waste Act, 2008 (NEMA) in July 2015.

■ Water Act 36 of 1998. ■ Mine Health and Safety Act, 1996. ■ Chamber of Mines Guidelines

(Volume 1). Of these, the COP governs the project in the long run and should be referred to on a consistent basis throughout the entire life cycle of the mine.