Rock fall derails TBM at Tapovan-Vishnugad HEP

A large chunk of rock falling on the Tunnel Boring Machine (TBM) deployed at NTPC's 520 MW Tapovan-Vishugad hydroelectric project (HEP) has put on hold virtually all excavation work at the Head Race Tunnel. The delay has been compounded by the heavy ingress of water in the tunnel, consequent to the ongoing monsoon rainfall.

• The contracted agencies, Larsen &Toubro Ltd (L&T) and Alpine Mayreder Bau GmbH of Austria, are, thus, in a race against time to complete this critical milestone by December 2010, against the previous deadline of June.
•  The consortium had bagged the HRT excavation contract at a sum of Rs 456 crore. The package includes construction of a concrete lined head-race tunnel of 11.3 km length, with a 5.6 m diameter. The project is being developed by NTPC across the Dhauliganga river in the Chamoli district of Uttarakhand.
•  Pertinently, persistent agitation by the local populace against the blasting work required for excavation of the power house at the HEP has already resulted in the project being deferred to March 2013, against the original commissioning schedule of the last quarter of 2011-12. The new mishaps are likely to push the project back further.