Chilean regulator and workers flagged risks at Teck’s Quebrada Blanca tailings dam

Workers and Chile’s Sernageomin raised alarms over cracks and leaks at Teck’s Quebrada Blanca tailings dam. The company insists the facility is stable and safe.

Chilean authorities raised concerns in August over a large crack and water leaks at the tailings dam of Teck’s flagship Quebrada Blanca copper mine, criticizing the company for not immediately reporting the incident, according to documents reviewed by Reuters.

The situation was serious enough that several workers asked the mining regulator Sernageomin to investigate potential safety risks, filing a series of complaints between July 28 and August 8.

The mine has faced issues at its tailings facility since 2024, forcing Teck to cut production guidance at Quebrada Blanca.

Teck, in written responses, insists that the dam is stable and safe, and that construction and ramp-up activities are continuing as planned.

“There was never any risk to the safety or integrity of the facility or to employees,” the company said.

Worker complaints: leaks and a large crack on the dam crest

The first concerns surfaced in late July, when workers observed leaks on the dam wall.

On July 28, a worker wrote to Sernageomin reporting water seeping through the wall of the tailings dam. The regulator’s inspection on August 1 was partly triggered by that complaint and another related to a lack of adequate personal protective equipment, Sernageomin said in its findings.

In the days that followed, more complaints arrived. Starting August 3, workers reported a large fissure along the top (crest) of the dam wall.

One complaint stated:

“There is a serious problem with the tailings dam wall and the information from the company is not very clear.”

Another worker wrote:

“Teck personnel ignore everything that’s happening and just don’t want to stop producing … I beg you to go to the workplace.”

Sernageomin finds 240-meter crack and pools of water

During inspections on August 1 and 2, Sernageomin identified a crack running about 240 meters (790 feet) horizontally across the crest of the main dam wall, with an opening of 18 centimeters. Inspectors also found pools of water at the base of the wall, raising further concerns about seepage and stability.

In its inspection report – signed by both Sernageomin and Teck representatives – the regulator rebuked the company for not promptly reporting the incident:

“The company must immediately or promptly notify the service of any incidents,” the report said.

A follow-up report dated August 5 noted that the regulator remained “concerned about what was observed in the field regarding operational findings on the deposit wall, specifically the water seepage and cracks on the crest.”

Since early August, Teck has been sending weekly monitoring reports to Sernageomin, detailing the condition of the dam and the measures taken.

Teck: cracks “not unusual” and quickly repaired

In its communications with Sernageomin – including reports, letters, presentations and minutes of weekly meetings – Teck said it had addressed the issues, informed workers they were not at risk, and carried out drills for potential structural collapse scenarios, while preparing a root cause analysis of the crack and leaks.

The company told Reuters that the cracks that appeared in late July were not unusual for this type of dam construction and were quickly repaired. Around the same time, Teck resolved a pipeline leak that it said had “resulted in water discharge.”

“Work is continuing as planned on the facility to enable full ramp-up of QB,” the company stated.

Teck has not specifically discussed the Sernageomin inspection or the crack and leaks in its financial disclosures. It has, however, explained that structural challenges at the tailings dam forced it to slash production targets for Quebrada Blanca and commit to spending US$420 million next year on improvements.

Strategic implications: Quebrada Blanca and the Anglo American merger

Analysts see the issues at Quebrada Blanca as a key factor behind Teck’s decision to pursue a merger with Anglo American, which shareholders of both companies have now approved. The combination will allow for potential synergies and shared operations between Quebrada Blanca and Anglo’s nearby Collahuasi mine.

Anglo American has said it supports Teck’s strategy for Quebrada Blanca and brings experience from tackling similar tailings challenges at its Quellaveco operation in Peru.

Even so, analysts warn that failure to get Quebrada Blanca’s output on track in the next few years could weigh on the valuation of the merged Anglo Teck group and its positioning as a major global copper producer.

Tailings safety under global scrutiny

The scrutiny of Quebrada Blanca comes as tailings dam safety standards are under intense global focus following the 2019 Brumadinho disaster in Brazil, where a dam collapse killed 270 people and triggered sweeping reforms in industry practices and regulations.

Tailings experts consulted by Reuters noted that cracks and leaks are potential red flags for dam stability, requiring continuous monitoring and a thorough understanding of their underlying causes.

As mining engineering professor Rennie Kaunda of the Colorado School of Mines put it:

“They are like symptoms at the doctor’s office. They may indicate some underlying, major sickness or disease if not addressed.”

In Quebrada Blanca’s case, the ongoing oversight by Sernageomin, the effectiveness of Teck’s corrective actions, and the transparency of future disclosures will be crucial to mitigating risk, rebuilding trust and ensuring the safety of the facility, its workers and nearby communities.