Due to the risk of heavy influx of water and sand into the pile holes, a concrete seal had to be installed at the bottom of each hole. The contractor, EMPA Engineering, a member of the Teixeira Duarte Group, needed a quick solution and there was no time for testing.
Instead, EMPA, a member of the Rio Barra Consortium, got started straight away with the cluster drill, boring holes for 55 piles with a diameter of 1.2 m and a depth of 31 m. Casing was installed in sandy soil to a depth of 26 m with an extra 5 m drilled into the bedrock.
Besides the influx of water, the cluster drill was hampered by a sloping soil/rock formation. Atlas Copco compressors working at a pressure of 10 bar (750 CFM) were used to power the equipment.
The first hole was completed in 2.5 hours in rock with a compressive strength of
200 MpA. The estimated time for completion was 20 days, compared to an earlier estimate of 80–100 days with other equipment.
Epiroc operated under the trademark “Atlas Copco” prior to January 1, 2018.