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Case description

While driving a vertical Alimak pilot for the construction of a large diameter ventilation raise, a mud slip was encountered that resulted in a large volume water inflow situated approximately 100 m up the raise and 200 m below surface.

The gold mining company contacted Peter White to provide hands-on engineering direction of Alimak crews to stop the existing water inflow and to improve ground conditions prior to resuming ventilation raise construction.

Solution

Peter provided comprehensive training for all of the Alimak crews to safely use chemical grout for water cutoff work. In addition, Peter provided training to contractor’s mechanics for maintenance and servicing of all grouting pumps and equipment.

An initial stage of chemical grouting was undertaken to stop the initial high-volume water inflow. After drilling shallow probe holes into the water flow path, chemical grout and pumping equipment were moved to the top of the raise using the Alimak climber.

Subsequent stages of systematic deep hole drilling with cement grouting were undertaken to displace water away from the future ventilation raise. After drilling deep holes from the Alimak platform, long high-pressure grout hoses were connected to the cement grouting equipment situated at the bottom of the raise.

Alimak crews successfully completed chemical and cement grouting stages of work over several weeks to eliminate water seepage in preparation for subsequent excavation and concrete wall construction.

After completion of all grouting work, the mud slip area was excavated to final diameter and reinforced by constructing a concrete wall prior to continuing the Alimak pilot raise to the surface.

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