Pipe jacking solution for West African power plant 25 Jan 2018

For the excavation of two tunnels to carry cooling water pipes to the new Kpone oil and gas power plant near Accra in Ghana, contractors Coleman Microtunneling, a subsidiary of Bothar Group Australia chose a customised 2.5m Herrenknecht AVND micromachine.

Four pipe jacking drives were completed between the Atlantic Ocean and the 2,700GWh per year plant that supplies electricity to a million households and businesses.

First, two tunnels of 545m and 520m were excavated from shafts at the coastline through weathered gneiss towards the power plant, then a tunnel of 1,085m length was excavated below the seabed from the coast to the water intake point and the machine was recovered from a depth of 17m before excavating another parallel tunnel of 380m length for the outfall.

The micromachine was supplied with a salvage module to prevent flooding to the tunnel and the TBM during recovery and a hyperbaric chamber to allow cutter tool changes under high groundwater pressure.

"We could not have constructed the tunnels without the support from Herrenknecht,” said Brent Jones, Project Manager for Coleman Microtunnelling.

Herrenknecht provided support at their headquarters in Schwanau, Germany and on site through trained local service staff.