Upper Tamakoshi Tunnel redesign will cost less than previous estimation: Panel


    DOLAKHA, OCT 21 –

    Access Tunnel Under-construction
    Access Tunnel Under-construction (Photo: http://tamakoshihydro.org.np)

    Changing the design of the Upper Tamakoshi Hydropower Project’s tunnel would cost less than what was previously estimated, a panel of experts looking at the matter has said.

    The German team represented by Wynfrith Riemer, a geologist, and Helmut Bock, a rock mechanic, concluded that the redesign would cost Rs 940 million, against Rs 1.5 billion estimated by Norwegian consultant SINTEF.
    The Norwegian firm had estimated that an additional penstock pipe would cost Rs 1 billion and rerouting of the tunnel would cost Rs 500 million. After a rock stress measurement four months ago, SINTEF had concluded the tunnel had to be realigned in order to prevent hydraulic fracturing and uncontrollable loss of water. It had highlighted the risk of water overflowing from the tunnel due to weak soil condition.
    However, the German panel of experts not only reduced the projected cost, but also the completion time. As per the new recommendation, the project will be completed seven months behind the schedule. The Norwegian firm had estimated that the project would be delayed by 15 months.
    “The recommendation is appropriate for the country,” said officiating project Chief Bigyan Prasad Shrestha. “The Nepal Electricity Authority (NEA) board should decide whether to implement this recommendation.” He said the study was carried out from October 4-14.
    The project was held in abeyance, citing weak geological conditions in the remaining 3.5 km section of the 8-km main tunnel.
    The panel’s recommendations include reducing the slope of the 3.5 km section of the 5-km tunnel from Bhainse audit to Penstock audit by 0.3 percent instead of previously suggested 8.3 percent and inserting steel lining in the 450-m section of the 500-m section that has already been dug in the Penstock audit of the main tunnel. The earlier study had recommended steel lining in more places.
    The new study has also recommended building 280 m of the remaining 420-m surge shaft, which will remain as upper Penstock shaft. Instead of the surge shaft, the consultants have recommended building a 920-m surge tunnel. The German team also recommended upgrading the 3-km road track to reach the new audit portal and digging a new 400-m audit tunnel.
    Shrestha said 52 percent work on the project has been completed.
    Source : Ekantipur