ABSTRACT
We aim to highlight the geotechnical methods implemented to manage water seepage during the construction of a hydropower project. The powerhouse site was situated at the location where the average depth was 24 to 26 meters. To facilitate construction, the river was diverted using a 280-meter-long coffer dam. However, during the monsoon in year 2023, the coffer dam was compromised by unexpected flooding, leading to the accumulation of overburden materials in the powerhouse area. To address the water influx, dewatering was done but no impact on water level. Following comprehensive geological, geotechnical, and hydrological studies, several potential recharge points were identified. In November 2023, the dewatering efforts revealed a water seepage rate of 1,167 cum/hour. To effectively manage the seepage, a combination of curtain grouting and sheet piling was employed, presenting various geotechnical challenges. This case study exemplifies the complexities involved in controlling water seepage in geotechnical engineering projects.
