Geotechnical Survey, Dredgeability Of Soil Sediments And Siltation Volume Of Brimsu Water Reservoir

Abstract

The water supply for the Cape Coast Metropolis of Ghana comes from Brimsu reservoir. The accumulation of soil sediments in the reservoir since construction and commissioning in 1928 has resulted in a drastic reduction of the storage capacity of the reservoir leading to perennial water shortages to the community. A dredging syst-em to desilt the sediments and to improve the storage capacity was investigated. The volume of siltation was determined by hydrographic and topographical surveys using Global Positioning System and Total Station Tec-hniques to obtain data on the area and thickness of the sediments. The rate of siltation had more than doubled since the construction. The geotechnical characteristics of the sediments showed the sediments were of unifor-mly graded sand with admixtures of clay and silt. The dredgeability of the sediments was characterized by geo-technical descriptor terms, indicating that the sediments could be dredged using cutter-type dredger for excava-tion, and transported by hydraulic pipelines to disposal sites. The study established that sustainable environme-ntal management is required to minimize the siltation of the reservoir and ensure regular water supply. Journal of Applied Science and Technology Vol. 12 (1&2) 2007: pp. 71-77