As global momentum builds to reduce the disposal of extractive waste at sea, deep-sea tailings placement (DSTP) has become one of the most scrutinised topics in the mining sector.
DSTP involves transporting tailings through a submerged pipeline and releasing them at depths greater than 100 metres. It is typically considered where terrestrial storage is constrained by land pressure, topography, community opposition, or environmental sensitivities.
While historically used where land-based solutions were infeasible, DSTP now sits at the centre of debates among regulators, investors, communities, and downstream supply chains. Mining companies evaluating DSTP face a rapidly evolving landscape: tightening regulatory expectations, shifts in ESG-driven capital allocation, growing stakeholder resistance, and rising scientific uncertainty about deep-sea ecosystems.
Mounting regulatory and financial pressures
International sentiment is shifting. Since the 2016 International Union for Conservation of Nature resolution calling for an end to marine disposal, jurisdictions like Indonesia have stopped approving new DSTP operations. Existing sites in Papua New Guinea, Turkey, and Norway continue to face legal and political challenges.
Regulators worldwide are moving toward greater constraints. International frameworks such as the London Protocol promote minimising marine pollution, while regional guidance requires that DSTP be selected only when demonstrably less impactful than land-based options. National authorities are tightening expectations around environmental and social impact assessments (ESIAs), monitoring programs, and stakeholder engagement.
Concurrently, DSTP has emerged as a major financing risk. Lenders and development finance institutions increasingly treat it as a last resort. Industry initiatives reinforce this trend: IRMA’s draft Standard indicates marine disposal does not meet certification requirements, and the 2026 Consolidated Mining Standard Initiative (CMSI) is expected to further tighten rules. For project financiers, DSTP is increasingly seen as a reputational liability.
Navigating environmental, social, and supply chain risks
Deep-sea ecosystems remain poorly understood. The long-term behaviour of tailings on the seafloor is difficult to model, raising concerns about smothering benthic ecosystems, disrupting deep-sea food webs, and the limited feasibility of remediation.
Communities and civil society groups frequently contest DSTP projects, particularly where subsistence fisheries are present, areas hold cultural significance, or indigenous groups exercise custodial rights. These dynamics heighten social licence risks and influence political decision-making.
Downstream supply chains are also raising requirements. Buyers in the technology, automotive, renewable energy, and jewellery sectors are embedding tailings governance into responsible sourcing. DSTP can now affect off-take agreements, market access, and eligibility for sustainability-linked financing.
Developing a Strategic Approach for 2026
Despite global headwinds, some governments continue to permit DSTP, even though strong scientific evidence shows it poses a lower overall risk than land-based options. SRK emphasises that DSTP can be used when legal, social, environmental, and reputational risks have been assessed and mitigated.
Mining companies should align DSTP planning with good international industry practice across design, impact modelling, stakeholder engagement, and independent technical reviews. Companies must prepare a well-structured management process to reduce risks, support permitting, and protect long-term asset value.
DSTP remains feasible in certain geographies but requires a heightened level of scientific rigour, financial due diligence readiness, and ESG transparency. Mining companies and investors should view DSTP as a multi-dimensional risk exposure and plan accordingly.
Read the original article from Australian Resources & Investment here.
