Water is being taken from the Yellow River near the village of Wanjiazhai – after which the gigantic project was named – pumped to an altitude of 960 metres first and then conducted via pipelines and tunnels eastwards. After about 42 kilometres (pumping altitude of 1,286 metres above sea level) the General Main splits into a North Main, which reaches the city of Datong after further 170 kilometres. The South Main will supply the capital of the Province, Taiyuan, after further 204 kilometres.

Multiple benefit

The three-phase project will not only improve the supply of drinking water but also of industrial water urgently needed for industry and agriculture, and it will also minimise the huge water losses. Construction work shall be completed by 2001. Project

is financed by the World Bank (USD 748 million) and comprises the technically most difficult tasks – the construction of the pumping stations, of the tunnels of the South Main and the so-called link to Taiyuan. In addition, the distribution of the water in the city, the construction of a water purification plant and the renewal and extension of the municipal water supply system have to be tackled.

Within Phase II a total of four tunnels with a total length of 90 kilometres have to be constructed. 87 percent of the this stretch travel inside geological formations that can be classified as mountain grade 1 to 3, i.e. solid formations. 13 percent of the tunnel stretch, however, has to be bored into soft soils like loess or sand.

With its total length of 42.6 kilometres, one of the single tunnels will belong to the longest water diversion constructions world-wide! Also the "inner values" of the tunnel tube are remarkable: the inner diametre measures 4.2 metres (in some sections even 4.3 metres), which adds up to an excavation diametre of 4.9 to 4.98 metre.

Clear calculation

These are enormous tasks bringing together Chinese engineering skills and Austrian know-how. However, the reason why D2 Consult from Linz was awarded the planning contract was a clear calculation. The company experts could prove that their construction method for the 90 tunnel kilometres was much faster and 15 percent cheaper.

These advantages are achieved with the automated and full-mechanical road heading using an "intelligent" boring shield whose integrated sensors permanently send data on deviations from the specified data and other failures. The tunnel will be lined with pre-cast concrete segments with integrated rubber seals and plastic pegs.

This advanced know-how allows to continuously push the tunnel forward. Interruption of boring works for the lining of the tunnel walls, as in conventional methods, are no longer necessary. D2 Consult planned to use four boring machines (TBMs) in the frame of the ATS 40-million (e 2,91-million) contract and thus achieved a possibly record-breaking total yield of 5,000 metres per month! The maximum daily yield the Italian subcontractor Impregilo achieved was 99 metres!

Incentive for engineers

In order to motivate domestic engineers to increasingly export their know-how the Ministry of Economics and the Austrian Consulting Association (ACA) created already 11 years ago the "Federal Prize for Consulting for Exportable Engineering Achievements". Last December this prize was – not in the least surprising – awarded to D2 Consult. Harald Wagner, one of the two founders of the company, said in his thanking address that he was convinced that the success of the Wanjiazhai Project would entail other contracts for domestic enterprises. D2 Consult itself was able to get similar contracts from Vietnam, Iran and Germany. (Source: aqua press Int. 1/2001)
Mag. Christof Hahn

Information & Contact:
D2 Consult
Dr. Wagner, Dr. Schulter GmbH & Co KG
Leonfeldner Straße 64,
A–4040 Linz Fax +43 732 713 812-4