On 10 March 2026, reports that four HPAL nickel smelters in an industrial estate in Morowali, Central Sulawesi, had temporarily stopped production made the national business news. The estate operator said the reports were not fully accurate, because only one of the four smelters was producing while the other three were still under construction (Bisnis.com, 2026b). Behind the story was a landslide at a waste stack three weeks earlier.
This case study summarises what credible sources had reported at the time of writing. No official investigation report is available, so we draw no conclusion about the cause. The victim and the contractor are not named.
What Happened
The landslide occurred on Wednesday, 18 February 2026, at around 14.00 local time in the waste disposal area of one of the estate's tenants (Mongabay Indonesia, 2026b). One worker died and heavy equipment was dragged down (Bisnis.com, 2026a). Mongabay reported that at least seven units, including excavators, bulldozers and trucks, were buried while operators were at work, and that the preliminary suspicion was soft ground beneath the stack (Mongabay Indonesia, 2026a).
It was not the first such event. A landslide in the waste area of the same estate also occurred in March 2025, and a civil society coalition said the series of events showed a systemic failure of waste and safety governance (Mongabay Indonesia, 2026a). In early March 2026, the government was reported to be reviewing the tenant (Mongabay Indonesia, 2026b).
Global Failure Patterns
Lin et al. (2022) analysed 342 tailings dam failures worldwide from 1915 to 2021. Failures occurred almost every year, at an average of 4.4 per year from 1947 to 2021, their frequency was rising, and most were directly linked to heavy rainfall or earthquakes. Asia accounted for 21.3 percent of the events, and failures in Asia and Europe were mostly related to hydroclimatic factors.
In 2020, ICMM, UNEP and PRI published the Global Industry Standard on Tailings Management (GISTM). It sets out 15 principles, classifies facilities by the consequences of failure, and requires clear roles, including an empowered Engineer of Record (Principle 9), independent review, and public disclosure of facility information (Principle 15) (Global Tailings Review, 2020).
Reading It Through GISTM
We read this case through GISTM because the standard was written for tailings storage facilities. Smelter waste stacks in an industrial estate are not always regulated in the same way as mine tailings dams, so we use the framework as a reference for good practice, not as a compliance yardstick.
On mechanism, two lines of inquiry are commonly examined, and both remain hypotheses. The first is foundation bearing capacity, which fits the early report of soft ground beneath the stack (Mongabay Indonesia, 2026a). The second is the role of water, since global data link most failures to heavy rain (Lin et al., 2022). We have no rainfall data or site investigation results, so neither can be assessed yet.
What is already clear is exposure. Equipment operators were working in the stack area when it gave way (Mongabay Indonesia, 2026a). In our view, this is the key lesson for occupational safety: a waste stack is a geotechnical structure, and anyone working on it or at its toe is in a zone that can be hit directly if it fails. A repeat event in the same estate also suggests that the 2025 lessons had not changed how the area was managed enough, although we cannot judge what steps were taken in between.
Governance matters too. GISTM requires clear roles, from an accountable executive to the Engineer of Record and independent reviewers (Global Tailings Review, 2020). In an estate shared by many tenants and contractors, we think the first question after an event like this is who holds those roles for each stack, and whether they have the authority to stop work when warning signs appear.
Lessons for Operators
- Treat tailings and solid waste stacks as engineered structures, with foundation studies, limits on height and slope, and review by independent experts (Global Tailings Review, 2020).
- Set no-go zones at the toe and active slopes of a stack, and limit the number of people and machines inside them at each stage of placement.
- Watch for early signs of instability such as cracks, seepage and slope movement, especially after heavy rain (Lin et al., 2022).
- Prepare stop-work and evacuation procedures that operators can trigger without waiting for layers of approval.
- Make sure contractors working on stacks understand the hazard through permits, induction and the same supervision as direct employees.
- Record and share the lessons from every event with all tenants in the estate, not only the affected unit.
How Nusa Safety Helps
Nusa Safety supports mineral processing operators through engineering studies and risk assessment and HAZID hazard identification studies that map the hazards of stack areas and the work around them. The Nusa Safety team can also assess contractor readiness through an HSE and CSMS audit and train teams through emergency preparedness drills. To discuss the needs of a specific site, please contact the Nusa Safety team.
This article is general information and not legal or professional advice for any specific case.
References
- Bisnis.com. (2026a, February 19). Longsor di kawasan IMIP Morowali tewaskan satu pekerja [Landslide in the IMIP Morowali estate kills one worker]. https://ekonomi.bisnis.com/read/20260219/44/1954093/longsor-di-kawasan-imip-morowali-tewaskan-satu-pekerja
- Bisnis.com. (2026b, March 10). IMIP buka suara soal kabar 4 smelter setop produksi imbas longsor [IMIP responds to reports that four smelters halted production after the landslide]. https://ekonomi.bisnis.com/read/20260310/44/1959240/imip-buka-suara-soal-kabar-4-smelter-setop-produksi-imbas-longsor
- Global Tailings Review. (2020). Global industry standard on tailings management. ICMM, UNEP and PRI. https://globaltailingsreview.org/global-industry-standard/
- Lin, S.-Q., Wang, G.-J., Liu, W.-L., Zhao, B., Shen, Y.-M., Wang, M.-L., & Li, X.-S. (2022). Regional distribution and causes of global mine tailings dam failures. Metals, 12(6), 905. https://doi.org/10.3390/met12060905
- Mongabay Indonesia. (2026a, February 23). Lagi, pekerja tewas tertimbun longsoran limbah nikel di kawasan industri PT IMIP [Another worker killed by a nickel waste landslide in the IMIP industrial estate]. https://mongabay.co.id/2026/02/23/lagi-pekerja-tewas-tertimbun-longsoran-limbah-nikel-di-kawasan-industri-pt-imip/
- Mongabay Indonesia. (2026b, March 3). Menanti sanksi tegas kasus kolam limbah nikel di Morowali [Waiting for firm sanctions in the Morowali nickel waste case]. https://mongabay.co.id/2026/03/03/menanti-sanksi-tegas-kasus-kolam-limbah-nikel-di-morowali/
