Geological aspects of seepage problem and its management at Khanpur dam project, Pakistan

Abstract

Seepage problem is one of the important tasks to be resolved associated with embankment dams. Often preconstruction arrangements are made to reduce the seepage through dam’s abutments and valley fill deposits. The usual treatments include grouting; cut-off wall, clay blanketing and dental treatments which are adopted to cut down the possible seepage paths. The amount of seepage and type of treatments are directly related to the nature of geological formations and associated structural features.

For the past twenty five years of dam operation seepage is still one of the major problem at Khanpur Dam Project. At maximum conservation level of 1980 feet seepage quantity is about 50% of the base inflows of the river and its increasing trend is a threat to the dam safety and water storage. The study of the geological aspects indicates that the major seepage paths are associated with limestone formations and through a number of normal faults in Chohae area. Instead of costly treatment over a large scattered area, management measures are suggested for conservation of reservoir and utilization of 35% of seepage water at gravity flow.