Restoration of Kakabeka Falls, Ontario, Canada

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Title: Restoration of Kakabeka Falls, Ontario, Canada

Author(s): R.G. Grieve , T. G. Carter, and R. B. Adamson

Publication: Special Publication

Volume: 128

Issue:

Appears on pages(s): 1225-1242

Keywords: erosion; formwork (construction); mixers; mix proportioning; pigments; plasticizers; rocks; Construction

Date: 11/1/1991

Abstract:
The crest of Kakabeka Falls, a major tourist attraction near Thunder Bay, Ontario, had changed rapidly within 15 years. Geotechnical evaluation had concluded that, due to the geometry of the rock formation, there was little continuous cap-rock beyond the crest of the falls. Undercutting by water and subsequent ice jacking and freeze-thaw action was eroding the remaining cap-rock. Without prompt remedial work, the falls would degenerate to rapids over 50 years. Rapid recession of the falls also threatened the foundations of two bridges. In 1988 and 1989, remedial works were undertaken to stabilize the erosion process and improve the appearance of the falls. Concrete mixes were designed using powdered color dyes to duplicate the color and appearance of the reddish brown cap-rock and black hales. The crest of the falls was reconstructed incorporating a weir which spread the water flow evenly across the width of the falls. Special formwork and hand-finishing techniques were used to texture the concrete surface to match the existing rock. Two years in planning and eight weeks in construction, the project successfully restored the falls to its former beauty.