Our Largest Shaft Reaches Target Depth
Posted by: admin February 19, 2015
In November, drilling of our southern coalfields vent shaft project reached its target depth of 516m. This is the deepest blind-bored shaft ever constructed by Abergeldie.
It is a monumental achievement for the drilling team; even greater considering the shaft’s unusually broad 6.2m diameter and the challenges of very hard rock in the lower strata.
Fabrication of the 170 composite steel/concrete liner units was carried out in a temporary factory facility which Abergeldie set up on-site. Each segment is 3m deep, with a finished internal diameter of 5m.
Another of the team’s major challenges has been working to the treat the drilling process water. The blind boring process uses up to 18 million litres of water, which carries away the drilled spoil as suspended solids. The concentration of suspended solids can be as high as 70%. The solids must be removed so that the process water can be reused again and again as boring proceeds. With the project nearing completion, efforts now turn to further fine tuning this treatment system to produce clean water.
Despite some delays in drilling due to unusually difficult ground conditions, the project should be completed in April 2015. Abergeldie is proud to be delivering a very significant project for a very valued client.