Thank you HB77 for the HLF manual linkVery informative
Not sure this should be widely touted as a catastrophic event, instead of an unforseen accident caused by an engineering failure by embankment breach. As someone else mentioned, is this an insurance covered accident?
Clearly the embankment failed to hold back the pads saturated material, so what caused the breach and what is the timeline to replace it with an improved embankment and potential damaged sump configeration.
Could have been far worse if they were in Phase 3 of the mines life, so lessons can be learned and improvements made.
Perhaps a reinforced concrete embankment lined with multiple liners can be incorporated, and proble solved for years to come.
“BGC (2017b) performed a dam breach analysis to provide input into evaluating the HLF embankment hazard classification, per Canadian Dam Association (2013) guidelines. The results confirm that the confining embankment can be classified as a Significant dam (i.e., there is no permanent population or infrastructure at risk in the inundation path, and restoration of fish and wildlife habitat is highly possible). Nevertheless, the environmental assessment, and subsequently the WUL, for the Project imposes an Extreme dam classification (the most stringent possible) for hydrologic and storage criteria. Thus, the Extreme hydrologic and storage criteria were used for the HLF design. A requirement to impose more conservative geotechnical criteria beyond those specified in the CDA guidelines were not included in the Yukon regulatory process; nevertheless, geotechnical criteria applied here assume a High hazard dam classification. The dam classifications used here also consider the input from the Application of Dam Safety Guidelines to Mining Dams (CDA 2014), and have been vetted during consideration and consultation between owner and regulators.”
https://emr-ftp.gov.yk.ca/emrweb/COMM/major-mines/eagle-gold/emr-mml-eg-heap-leach-facility-oms-manual-2020-01.pdf