Construction of the kettle rapids hydro development

Abstract

The Kettle Rapids hydro development is being constructed in Canada in the northern part of Manitoba on the Nelson River, 105 krn from Hudson Bay. It is planned to construct 12 hydroelectric stations with a total installed capacity of 7200 MW on the Nelson (length 600 km), flowing from Lake Winnipeg, and its tributaries. The largest in the sequence will be the Limestone station, with a capacity of 1800 MW. At present the 338-MW KeRsey station is in operation and construction of the 1220-MW Kettle Rapids station is being completed. The hydro development is being constructed under cold climatic conditions in a region of insular permafrost. The climate of the construetion region is subarctic, temperate-continental with a large temperature range and small precipitation depth. The mean annual temperature is -5"C, minimum winter-49.5*, and maximum summer 32.3~ there are about 100 frost-free days during the year. The mean annual rain depth is 0.31 m and snow, 1.26 m. The average flow of the Nelson at the site of the hydro deveRopment is 2200 mS/see.The structures of the hydro development ( Gneissic rocks occur in the powerhouse foundation (Fig. 2) and spillway and sand-graveR soils In the foundation of the earth dam (Fig. 3). The presence in the foundation of permafrost with ice interlayers and also of weak zones in the pit of the earth dams required removing the weak rocks and ice to a depth of 15 m and installing sandfilled vertical drain wells.The planning and surveying work was begun in 1962 with the scheme of using the Nelson River. The plan of the Kettle Rapids hydro development was drawn up in 1965-196"/and its construction begun in 1966 with the construction of a temporary village, roads, and temporary facilities. The flat terrain, layout of the hydro development in which the concrete structures (powerhouse and spillway) are adjacent to the right bank, and the main approaches to the hydro development predetermined the right-bank location of the entire construction site and residential village.