Findings regarding the March 30 dust incident

April 8, 2022

Fermilab apologizes for the March 30 incident where Fermilab operations resulted in dust in Manuel Brothers Park and shares the concerns of the city and the public. We recognize there was a problem and that the level of dust has been unacceptable. We understand the community’s frustrations. Fermilab is committed to continuing to work on all feasible solutions until we find the best possible course of action.

Fermilab has finished its investigation of the March 30, 2022 rock conveyor operation, which led to dust and tackifier covering the snow in Manuel Brothers Park in Lead. Fermilab stopped operations of the rock conveyor at about 11:30 a.m. MT that day. Crews began to clean Manuel Brothers Park that afternoon and the following day. Operations of the conveyor were suspended pending the results of the investigation.

Summary of the investigation

The investigation revealed that personnel should not have operated the rock conveyor on March 30. Sustained wind speed exceeded 15 mph that morning. Procedures and controls for rock conveyor operation that were put in place in December were not appropriately followed on March 30. The investigation identified corrective actions to strengthen these procedures and controls and training of personnel to ensure the controls will work as designed to prevent newly excavated material dust from being blown into the park and adjacent areas.

Fermilab presented the findings of the investigation and the corrective actions being taken to SDSTA on April 8.

In addition, Fermilab continues to work on a solution to contain the older dust coming from material previously deposited in the Open Cut that has not been treated with tackifier. Fermilab is committed to resolving this issue, which is unrelated to the failure that led to the March 30 dust incident, as quickly as possible.

What was the cause of the dust blown into the park and adjacent areas on March 30?

Rock was discharged into the Open Cut from 8:00 until 11:30 a.m. on Wednesday, March 30, 2022, while wind exceeded the 15 mph sustained wind control that had been put in place in December for the operation of the rock conveyor. This was caused by human error as personnel should not have operated the rock conveyor when sustained wind exceeded 15 mph. This led to a visible mixture of dust and tackifier on the snow in the park.

Why did the conveyor operate on March 30 when sustained winds were above 15 mph? What did the investigation find?

Controls implemented in December 2021 specify that the rock conveyor can only be operated when sustained wind speed is below 15 mph and personnel stationed at the Open Cut observe no dust leaving the Open Cut.

The investigation found that on March 30:

  • At the beginning of the shift, personnel obtained and reviewed outdated wind speed data due to human error. Based on that outdated data, personnel made the decision to begin operating the rock conveyor that morning.
  • Personnel failed to monitor the wind speed while rock was being discharged into the Open Cut.
  • Personnel stationed at the Open Cut were not able to observe dust leaving the Open Cut due to limited visibility as a result of heavy snowfall.
  • Personnel working that day were not properly trained regarding control measures and actions to be taken when sustained wind speeds exceed 15 mph.

The investigation determined that the root cause for these failures was that the updated procedures and controls for rock conveyor operation that were put in place in December were not implemented in an effective manner and not all personnel were effectively trained.

What corrective actions is Fermilab taking?

Fermilab has taken the following corrective actions:

  • Fermilab conducted an analysis to determine gaps in the existing discharge provisions.
  • Fermilab has developed a new Standard Operating Procedure for the rock conveyor with a clearer description of roles and responsibilities and a clear definition of the controls that need to be in place when rock is discharged into the Open Cut.
  • Fermilab has implemented a more comprehensive training plan for rock conveyor operation and has begun to retrain personnel involved in operating the rock conveyor and monitoring its operation.
  • Only retrained personnel will be allowed to monitor rock conveyor operations and make the decision to operate the conveyor.
  • Fermilab will update controls to automatically alert the operators when sustained wind speeds exceed 15 mph.

When will Fermilab resume operation of the rock conveyor?

If weather conditions allow, Fermilab will resume rock conveyor operation on April 8 with the updated controls in place.