SUITABILITY OF THE KIPWEN RIVER BASIN SOILS WITH RESPECT TO EARTHDAM CONSTRUCTION

The Kipwen river dam will supply water to the Flax Centre water supply project in the Uasin Gishu District in the Rift Valley Province in Ke nya. The dam will be a sixteen metre high earthfill dam constructed wi th the locally available materials to minimise construction costs. The geotechnical properties of the dam embankment, spillway and the futur e reservoir areas were determined to assess their suitability with res pect to the design and construction of the dam elements and its ancill aries. It was established that the foundation of the dam will be on so und impermeable phonolite rock while the residual soils, namely the re d silty clay (red coffee soils) and the brown clayey gravel (murram) w ill offer excellent water barrier when compacted at standard compactio n and OMC (T99) to form a zoned earthdam. The construction materials w ill be obtained from the reservoir area. This will not only increase t he volume of the reservoir slightly but equally important it will mini mise environmental degradation of the forested dam site.