6
to ensure that the activities were not further damaging the
wall or causing the failing mass to accelerate.
North Toe Removal
Removal of material against the base of the northern wall
proved to be challenging as the north wall instability became
quite sensitive to any removal of material. The mine used
several different tactics to overcome this obstacle.
In 2016, the mine implemented a fast-paced mining
method against the toe of the north wall. This essentially
meant that Mine Operations would remove as much as pos-
sible, and as quickly as possible, and then retreat to allow
the wall to settle. While this method worked, it would
negatively affect the upper slope stability. This resulted in
periods where no mining occurred as the high wall had to
settle, slow down, and de-accelerate. However, the average
velocity would continue to increase. By the end of 2016,
the mine had to repair the haul road daily, and the area had
an average velocity of about 33 inches per day. This was
deemed too excessive, and mining activities were halted.
When the mine resumed activities against the north
toe in 2018, the mine implemented tactics that maintained
a manageable average velocity rate of the highwall and haul
road. Previous radar data from 2016 showed that deforma-
tion of the upper slope and haul road would be manage-
able if the average velocity could be maintained at equal
to or less than 15 inches per day (with no acceleration). To
achieve this, mining decisions were heavily based on what
the radar monitoring was indicating. If the average veloc-
ity remained constant and within the accepted parameters,
no changes were made to the mining activities in the pit.
However, once an unacceptable change was discovered,
both the engineering team and Mine Operations reacted
quickly to adjust.
Adjustments made included periods of extremely slow
mining, where a maximum of 25,000 tons were removed
per day from the pit, periods where the tonnage rate was
as fast as possible, specific placement of the shovel in the
dig face, or even pulling out all operations and letting the
pit ‘rest’. At times, multiple types of adjustments were used
within the same 24-hour period to maintain the desired
average velocity. These tactics were implemented until the
pit was successfully completed in 2020.
CONCLUSIONS
Successfully managing rapid and excessive slope deforma-
tions would not be possible without state-of-the-art radar
slope monitoring devices and a team of engineers and oper-
ators who are willing to think outside of the box when it
comes to mine design and implementation.
Creative mining methods and discussions surrounding
acceptable risks should be brought to the table when a mine
is facing challenging slopes and traditional approaches are
not working.
This mine proved that by applying radar slope moni-
toring with creative mining methods in areas with extreme
deformation, an actively deforming high-wall and haul
road could be maintained so that personnel and equipment
could have safe access. This unique approach to mining
resulted in approximately 80 million additional contained
pounds of copper being produced from the pit, with no
injuries to personnel or equipment.
REFERENCES
[1] Yang, D. (2013). (tech.). Ruth East Pit – Preliminary
Geotechnical Assessment on December 2012 North Wall
Instability. Vancouver, Canada: Knight Piesold.
[2] Yang, D. (2014). (tech.). Robinson Mine – November
2014 Pit Slope Inspection. Vancouver, Canada: Knight
Piesold.
[3] Yang, D. (2015). (rep.). Robinson Mine Ruth Pit
Geotechnical Inspection. Vancouver, Canada: Knight
Piesold.
[4] Yang, D. (2016). (rep.). Ruth East Pit North Wall 2016
Geotechnical Site Investigation Program. Vancouver,
Canada: Knight Piesold.
[5] Yang, D., &Yong, S. (2017). (rep.). Robinson Mine
– Ruth East Pit North Wall Numerical and Rockfall
Modeling. Vancouver, Canada: Knight Piesold.
[6] Yang, D., &Yong, S. (2018). (rep.). Robinson Mine –
July 2018 Pit Slope Inspection and Stability Modeling.
Vancouver, Canada: Knight Piesold.
[7] Yang, D., &Yong, S. (2019). (rep.). Robinson Mine –
March 2019 Ruth Pit Inspection. Vancouver, Canada:
Knight Piesold.
[8] Yong, S., Yang, D., Ealy, J., &Foster, C. (2022).
(rep.). Managing Excessive Pit Wall Deformation of
Weak Rock Mass. Vancouver, Canada: Knight Piesold.
to ensure that the activities were not further damaging the
wall or causing the failing mass to accelerate.
North Toe Removal
Removal of material against the base of the northern wall
proved to be challenging as the north wall instability became
quite sensitive to any removal of material. The mine used
several different tactics to overcome this obstacle.
In 2016, the mine implemented a fast-paced mining
method against the toe of the north wall. This essentially
meant that Mine Operations would remove as much as pos-
sible, and as quickly as possible, and then retreat to allow
the wall to settle. While this method worked, it would
negatively affect the upper slope stability. This resulted in
periods where no mining occurred as the high wall had to
settle, slow down, and de-accelerate. However, the average
velocity would continue to increase. By the end of 2016,
the mine had to repair the haul road daily, and the area had
an average velocity of about 33 inches per day. This was
deemed too excessive, and mining activities were halted.
When the mine resumed activities against the north
toe in 2018, the mine implemented tactics that maintained
a manageable average velocity rate of the highwall and haul
road. Previous radar data from 2016 showed that deforma-
tion of the upper slope and haul road would be manage-
able if the average velocity could be maintained at equal
to or less than 15 inches per day (with no acceleration). To
achieve this, mining decisions were heavily based on what
the radar monitoring was indicating. If the average veloc-
ity remained constant and within the accepted parameters,
no changes were made to the mining activities in the pit.
However, once an unacceptable change was discovered,
both the engineering team and Mine Operations reacted
quickly to adjust.
Adjustments made included periods of extremely slow
mining, where a maximum of 25,000 tons were removed
per day from the pit, periods where the tonnage rate was
as fast as possible, specific placement of the shovel in the
dig face, or even pulling out all operations and letting the
pit ‘rest’. At times, multiple types of adjustments were used
within the same 24-hour period to maintain the desired
average velocity. These tactics were implemented until the
pit was successfully completed in 2020.
CONCLUSIONS
Successfully managing rapid and excessive slope deforma-
tions would not be possible without state-of-the-art radar
slope monitoring devices and a team of engineers and oper-
ators who are willing to think outside of the box when it
comes to mine design and implementation.
Creative mining methods and discussions surrounding
acceptable risks should be brought to the table when a mine
is facing challenging slopes and traditional approaches are
not working.
This mine proved that by applying radar slope moni-
toring with creative mining methods in areas with extreme
deformation, an actively deforming high-wall and haul
road could be maintained so that personnel and equipment
could have safe access. This unique approach to mining
resulted in approximately 80 million additional contained
pounds of copper being produced from the pit, with no
injuries to personnel or equipment.
REFERENCES
[1] Yang, D. (2013). (tech.). Ruth East Pit – Preliminary
Geotechnical Assessment on December 2012 North Wall
Instability. Vancouver, Canada: Knight Piesold.
[2] Yang, D. (2014). (tech.). Robinson Mine – November
2014 Pit Slope Inspection. Vancouver, Canada: Knight
Piesold.
[3] Yang, D. (2015). (rep.). Robinson Mine Ruth Pit
Geotechnical Inspection. Vancouver, Canada: Knight
Piesold.
[4] Yang, D. (2016). (rep.). Ruth East Pit North Wall 2016
Geotechnical Site Investigation Program. Vancouver,
Canada: Knight Piesold.
[5] Yang, D., &Yong, S. (2017). (rep.). Robinson Mine
– Ruth East Pit North Wall Numerical and Rockfall
Modeling. Vancouver, Canada: Knight Piesold.
[6] Yang, D., &Yong, S. (2018). (rep.). Robinson Mine –
July 2018 Pit Slope Inspection and Stability Modeling.
Vancouver, Canada: Knight Piesold.
[7] Yang, D., &Yong, S. (2019). (rep.). Robinson Mine –
March 2019 Ruth Pit Inspection. Vancouver, Canada:
Knight Piesold.
[8] Yong, S., Yang, D., Ealy, J., &Foster, C. (2022).
(rep.). Managing Excessive Pit Wall Deformation of
Weak Rock Mass. Vancouver, Canada: Knight Piesold.