Power house excavation slope failure and remedial works in Kameng Hydro Electric Project (600 MW), Arunachal Pradesh

Excavation slope failure on Northern side of Power House of Kameng Hydro Electric Project (600 MW), Arunachal Pradesh, India located in lesser Himalayan Region paused as a major challenge in execution of the Project in general and Power House in particular. Geological complexity primarily due to proximity of Main Boundary Thrust (MBF) triggered the failure. The geological adversities could not be properly mapped during DPR stage due to topographical constraints, limited budget, etc. Failure of the slope entailed huge time and economic loss for the Project. Remedial measures on a continual basis were carried out to restore the site. Execution of major items as part of remedial measures although not included in the original contract documents were carried out. Routine Civil and Electro-Mechanical works of Power House could be resumed after successful completion of remedial works vis-à-vis slope failure. In this paper, the details of slope failure problems encountered and remedial measures adopted are discussed with necessary incorporation of relevant sketches/photographs/data.