Drillings at Kivetty in Konginkangas

According to Government's decision in principle Teollisuuden Voima Oy is obliged to make bedrock investigations for the final disposal of the spent fuel produced by its power plant in Olkiluoto. Areas in Kuhmo, Hyrynsalmi, Sievi, Konginkangas and Olkiluoto were selected for the preliminary site investigations to be carried out during years 1987-1992. In Kivetty, Konginkangas the investigation program was started in spring 1988. During years 1988-1989 a deep borehole (1019 m) and 4 about 500 m deep additional boreholes were core drilled in the area. The structure of the holes makes it possible to carry out many investigations in the holes. Various parameters were measured from the flushing water during the drilling. Corelogging included collecting detailed data of fractures and determining the weathering degree and petrographical properties. Rock mechanical properties, uniaxial compressive strength, Young's modulus and Poisson's ratio were measured from core samples. The flushing water needed in the drillings was pumped from 100 m deep borehole wells drilled with down-the-hole method in the vicinity of the borehole. The water was labeled with 2 tracers before use. 30 vertical holes were core drilled down to the depth of 10 m in bedrock with a light drilling unit. Drilling was carried out in order to determine the thickness of the overburden to investigate the geophysical anomaly sources and to support geological mapping in areas covered with overburden. Groundwater hydraulics is one of the main subjects during the preliminary site investigation phase. For that reason 7 multilevel piezometers were installed on the site to monitore hydraulic head in 3 levels in the uppermost part of bedrock. The work consisted of borehole drillings to the depth of 100 m, geophysical borehole loggings and installation of piezometers. In addition about 65 shotholes were drilled for VSP-, tubewave and seismic measurements