Thin plastic clay seams existing in the upper Shivalik formations caused hazardous geotechnical problems during the construction of 144 MW capacity Chilla Power House Scheme, Hardwar, India by initiating several land slides. In addition, serious seepage problems occurred with the commissioning of the scheme. The paper describes in detail, the events of slides & seepage problems faced and the remedial measures adopted to counteract them. The data observed on the instruments installed to keep a vigil on the performance of the structure has also been analysed and discussed
