by Trinh Anh Duc
31-12-2002
Construction of the Hai Van Tunnel in Vietnam, a crucial section of National Highway 1 linking central Hue Thua Thien Province and Da Nang City, was placed in jeopardy by a large continuous water leak.
Engineers and workers, under the guidance of the Louis Berger Group, working as project managers on the project, temporarily plugged the subsoil water, which was leaking into a ventilation tunnel. The subsoil water source is 900 m from the mouth of the ventilation tunnel with a water volume discharge of 300 m3/hour.
The project team, headed by the LBG's project management group, claimed to have undertaken comprehensive preparations before construction, but stated that the landslides were unavoidable, although it now admits it could have used the geotechnical expertise resources of its Canadian affiliate consulting firm, Klohn Crippen Consultants, to better understand the underground conditions before permitting the construction work to go ahead.
The water leak seems to have occurred due to a fault in the geological layer through which the tunnel passes.
The three-tunnel project cost $251 million, with 85 percent of the financing coming from official development assistance loans provided by the Japan Bank for International Cooperation.
The tunnel system will consist of a main traffic tunnel with a total length of nearly 6.3 km, a tunnel for maintenance, a cross-line tunnel, a ventilation system, a lighting system, and a fire prevention system.