Olifantsnek | Geotechnical drilling
In September, our team of Geomech Africa drillers arrived in the North West Province of South Africa to begin a three-week drilling project. The brief was to conduct geotechnical drilling and core recovery at twelve holes, each 20 meters deep, at three different sites. These sites were 25 kilometres apart, so the team divided into two teams and worked simultaneously.
The team used YWE D90 drill rigs designed and built by Geomechanics. These rigs are well-suited for drilling in a variety of conditions, including the hard rock and boulders found in the North West Province.
The team began by clearing the working path with a TLB in order to have each rig reach its targeted drilling location. Then, they used cranes to place one of the rigs to position while the other could be tracked to its location
Once the rigs were in place, the team began drilling. They used NWD4 core barrels with NWS casing. SPTs (Standard Penetration Tests) were performed until refusal with the added collection of Shelby samples at some of the drill positions. At three of the drill holes, the team were tasked with the installation of PVC piping for standpipe piezometers for long-term water level monitoring.
One of the challenges the team faced was the hard rock and boulders they encountered while drilling on the sides of a bridge in the area. To ensure quality core recovery, the team shortened the drill runs and used casings to prevent the rock from grinding. The teams also drilled in 2 groups, which allowed them to complete the drilling at one site together and then move to the next site together.
One of the drill positions required the team to take down cattle fences. The team obtained permission from the farmer, to take down the fences. The fences were reinstated to their original condition and quality at the end of the drilling using a specialized fencing tensioner tool sourced locally.
The team completed the twelve holes on schedule and within budget. The core samples were boxed and collected at each position and delivered to the client for analysis. Another successful project completed.