Abstract: The significant leakage was found at a water supply reservoir for a key construction project. This leakage might be resulted from the failure of the seepage curtain of the dam and therefore it is difficult for the geotechnical investigation. The location of the leakage, the seepage mode and the magnitude of the leak were able to be detected based on various investigation techniques. The successful geotechnical investigation for the leakage provides information for the mitigation project. This paper presents the summary of the case history for the complicated investigation in this project.

Key words: Dam Leakage, Geotechnical Investigation, Seepage Curtain Structure, Groundwater Flow Detection