Abergeldie was contracted by Centennial Coal’s Newstan Mine to sink and line a 180m deep, 6m finished diameter shaft. Liners were steel only rather than the traditional steel/concrete composite liners which have been previously used on other shafts.
Due to clay bands in the strata Abergeldie used drill muds to prevent water absorption and maintain the integrity of the shaft walls. The unstable ground meant a large amount of soil needed to be excavated and benched to successfully install the pre-sink foundations. The sites footprint was very small and, as such this constraint has required the some creative thinking and ingenuity in installing the sedimentation ponds. Careful calculations and lateral thinking allowed the installation of 2 sufficient sedimentation ponds to allow for effective settling of the water which to be then used in the reverse circulation process of removing cuttings from within the shaft.
* Photos are courtesy of Centennial Coal