GREY:NEVDQ - Post by User
Comment by
RockDoc1on May 05, 2021 3:00pm
120 Views
Post# 33133711
RE:OT: Pit wall collapse - too much rain?
RE:OT: Pit wall collapse - too much rain?Hi Bog
The incident occurred February 2021. New Gold's New Afton block cave is underneath an existing open pit that was operated by Teck in the 1970-1980's. The cause of the incident is still under investigation.
In block caving, it is assumed that the cave will propagate to surface, potentially causing near surface soil and water to be drawn into the cave column. It is possible for the soil/water to appear in the underground workings, sometimes quickly and unexpectedly. The term for this is a "mud rush". Mud rush is one of the known major hazards with caving mines. Significant risk management procedures are put in place to manage the risk of mud rush.
Mud rushes are not confined only to caving mines. In 1980, there was a mud rush in the Balmoral underground mine in Quebec, killing 8 miners, with 16 more miners barely escaping with their lives.
Mud rush is also a potential hazard for any "near surface" underground operation, potentially including PH. There are a number of engineering design considerations (surface crown pillars, rockmass characterization and ground monitoring, etc) in preventing this from happening.
So, in theory, it is possible at PH, but the risk of mud rush at PH is likely very small and was certainly a major consideration in the PH engineering design.
RockDoc