Principal research scientist, Commonwealth Scientific Research and Industrial Organization, Melbourne,
Associate professor, School of Civil Engineering, University of New South Wales, Sydney,
Engineer, National Capital Development Commission, Canberra,
Water chemist, Melbourne and Metropolitan Board of Works, Melbourne,
Pages: 11 Published: Jan 1977
Construction of reservoirs and dams in areas with dispersive soil poses several major problems: safety of the retaining walls, safety of the containing slopes, erosion resistance on exposed surfaces, and quality of the storage water. Important aspects of some of these problems are discussed with particular reference to a major new city reservoir constructed recently by the Melbourne and Metropolitan Board of Works on Cardinia Creek, Victoria, Australia. This offstream reservoir stores high-quality, low-turbidity water brought by conduit from other major catchments.
Because there was a potential turbidity problem due to the dispersive nature of the reservoir soils, it was recommended that the ionic concentration of the water be increased by adding specific amounts of salts of calcium or a mixture of salts of calcium and sodium in specified proportions.
Raw gypsum (calcium sulphate dihydrate) was added to the water at the reservoir inlet. The result has been that the clay suspended in the water at the commencement of first filling flocculated and settled, as expected, so that the water is now clear and the whole storage appears to be performing satisfactorily in all respects.
A method for comparing the economic merit of soil versus water treatment is described.
clays, dispersions, soils, water storage, reservoirs, slope, stability, soil structure, erosion, water quality, water treatment, gypsum
Paper ID: STP26988S