Advanced Construction Techniques was awarded the project by Vale Canada Limited through a Best Value RFP process. The project consisted of drilling and high pressure grouting to establish a seepage control grout curtain around the locations of two future 18 foot diameter air shaft raises, the No. 1 Fresh Air Raise the No. 1 Return Air Raise at the Totten Mine.
The drilling and grouting treatment was performed at depths of 650 feet from the surface. The work included overburden drilling, DTH water hammer percussion rock drilling, borehole directional survey and video imaging, borehole washing, permeability water testing, and pressure grouting using balanced stable grout formulations. A modified downstage grouting method was required to treat the highly permeable zones at the various depths in a primary/secondary sequence. Every rock stage was imaged using an optical borehole camera to determine the best packer placement amid the highly fractured rock to reduce the risk of stuck tooling. This operation also allowed for detailed fracture analysis of the permeable zones.
Pressure testing and grouting activities were monitored in real time using our patented IntelliGrout® system. Pressure and flow were carefully observed by a Professional Geologist to ensure proper treatment and grout refusal parameters.
Pump recovery tests were performed at one of the shaft locations to produce conclusive results of reduced permeability. The project was very successful in attaining reduced rock permeability and allowed raise bore activities to follow without interruption.