An important operational measure taken by the company is the control of the ingress of water to the Gaby 4 stope that occurred with the formation of the sinkhole. To meet this objective, the company executed a contingency plan which included the construction of walls to seal and isolate the affected sector.
To this end, a complex and high-level engineering project was developed to design and build the structures that allow the passage of water to be sealed at four access points to the mansion.
The works were carried out at an average depth of more than 200 meters and each one considered an eleven-meter-wide concrete wall, with anchoring, drainage, and monitoring systems.
The construction of the walls is already finished, and we are currently monitoring the area with cameras and measuring instruments.
Ojos del Salado has developed a policy of transparency and willingness to collaborate with the authority, providing all available information and carrying out studies that help analyze the origin of the sinkhole and have information that gives peace of mind and certainty to the authorities and community of Tierra Amarilla.
Detail of engineering works for water ingress control:
The works were carried out at a depth of more than 200 meters. Specifically, four points were selected for the structures that allow to seal the passage of water: two at level 270, one at level 200 and another at level 290.
The area was thoroughly cleaned. This phase was relevant, as it facilitated the anchoring against the live rock, since, if the concrete is applied and there is dirt or gravel on the ground, the water could pass through these materials, then all the concrete goes to live rock.
Meshes were installed to protect the safety of the workers, which were removed once the work was completed.
Pipes were installed in the body of the tunnel walls that are at levels 200 and 270 meters deep. The purpose of the pipes is to divert water so that these sectors are not flooded at the time of construction, so that concrete can be poured.
The walls were built inside straight caverns. These are made of concrete and were attached to the cavern wall using steel anchors (around 500 anchors).
Construction iron (anchoring) is a high-quality steel that is widely used in mining because it is highly resistant. In this way, these anchors will stop this seal when the water begins to rise.
Horizontal structures: two walls 11 meters wide and with the height of the cavern (approximately 6 meters high) were built. One of them was concreted at level 200, and the other at a depth of 270 meters.
The works that were done in the tunnels that are 200 meters deep have control and monitoring instrumentation in all the seals to monitor the behavior of the «seals».
Rock seal exterior stability control extensometer: Monitoring systems were installed in rock-seal contact to timely identify potential deformations of the rock mass that put the stability of the sector at risk.
A seal stress sensor was also installed outside the flooded area, to timely identify potential deformations of the rock mass that put the stability of the sector at risk.
A vibrating wire sensor was also installed, which will measure the hydrostatic pressure and the level of water that is exerted on the wall and the gallery.