The first tidal power station in North America is founded in a weak sandstone. Geotechnical engineering during design and construction was of a practical nature. Only limited quantitative data was collected on the quality of the sandstone prior to design and construction. Considerable reliance was placed on a subjective appraisal of the engineering properties of the sandstone. The paper outlines the geotechnical engineering involved, the nature of the sandstone and the geotechnical design parameters selected.


The first tidal power station in North America is founded in a weak, highly weathered sandstone. The Triassic sandstone underlies the site in eastern Canada of the Annapolis Tidal Power Station at Annapolis Royal, Nova Scotia, Canada.

The Tidal Power Corporation, a Nova Scotia Crown Corporation, is designing and supervising construction of the underground single-effect tidal power generating station at the head of the Annapolis Basin, an inlet of the Bay of Fundy, using head provided by the Fundy tides. The 46 million dollar(Can.1981) project is designed to assess the operational characteristics and reliability of a proto-type large diameter(7.6 m) straight-flow turbine called the STRAFLO, developed by Escher Wyss of Zurich, Switzerland(Ref.1.).

The turbine potentially could be used to develop the extensive low head river hydro potential available in Canada including the many river and tidal power sites in the Province of Nova Scotia. These include major tidal power sites in the upper reaches of the Bay of Fundy where tidal ranges are as great as 17 m. The STRAFLO turbine will generate power at heads as low as 1.4 m. It is rated at 5.5 m with and output of 17.8 MW.

The power station is presently under construction(May 1981)- the first concrete was placed early in May-and is scheduled for completion in 1983. Construction began in July 1980 with the 27 m deep powerhouse excavation and accompanying cofferdam.

The final dexision to proceed with the project was not made until the summer of 1979. Partly because of the uncertain status of the project and the short time schedules, geotechnical studies of the site were not begun until then, the studies were made during the summer of 1979 and early 1980. As a result geotechnical engineering of the project throughout has been of a very practical nature. This paper outlines the results of the geotechnical studies and the simple procedures used in determining the geotechnical design parameters for the sandstone.


The location of the tidal power site on the south east side of the Bay of Fundy is 175 km west of Halifax, a major port on the east coast of Canada, and 20 km northeast of the entrance to the Annapolis Basin from the Bay of Fundy.

The site is on Hog's Island at the head of Annapolis Basin and in the lower reaches of the Annapolis River near the town of Annapolis Royal.

The tidal power project makes use of an existing barrage and sluice gate structure constructed across the river in the early 1960's.

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