Testa concrete face rockfill DAM

The Teesta Concrete Face Rockfill dam is under construction in the State of Sikkim. The project construction started in 2008 and is presently in advanced stage of completion (likely completion March 2015) in spite of stoppage of work for about 18 months due to earthquake and cloud burst in the project area and the other contract issues with the owners and contractors. The 60 m depth of the overburden in the riverbed with boulders present ruled out excavation upto fresh rock and hence CFRD with upstream plastic concrete cut-off wall (60 m Deep) was adopted. This paper focuses on design and construction characteristics of CFRD in such respect as general layout, cross section design, facing design, design of joints and water stops, foundation treatment etc. The purpose of this paper is to highlight the constructional advantage compared to other types of dam especially in respect of easy availability of embankment materials as well as shorter construction period independent of seasonal change. Also the possible division of foundation treatment and embankment work, high resistance against earthquake and stability against water leakage is the additional advantage. Largely the design and construction of this CFRD has been based on principles and experiences as applied internationally and gained from the Dhauliganga CFRD of NHPC with regard to zoning, fill materials, foundation excavation, grouting plinth and face slab etc. The constructional features of CFRD have been enumerated in the paper for future reference as well.