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DESIGN AND CONSTRUCTION OF SHORE LINE FORTIFICATION TO PROTECT MAIN LINE RAILWAY, PORT HOPE, ONTARIO

Session: Transportation and Linear Infrastructure III / Transports et infrastructures linéaires III

Colin Alston, Alston Geotechnical Consultants Inc. (Canada)
Mario Ruel, CN Rail (Canada)
David Howett, CN Rail (Canada)

The shoreline bluffs along the north shore of Lake Ontario at Port Hope have experienced ongoing erosion for a long period of time. When the CN Mainline was constructed in 1856 the distance between the railway right-of-way and the crest of the bluffs was more than 60 m. Ongoing erosion has had reduced this width to a few metres in the late 1990's and would compromise the safety of eh railway lines unless arrested.

The bluffs are about 16 m high at the shoreline. The soil profile consists of an upper layer of dense silt to fine sand lying on hard silty clay till. Groundwater movement through the upper layer is from north to south, towards the lake, which was causing internal erosion and the development of large chasms at the slope face. Toe erosion was occurring at the base of the slope.

Stabilization of the slope was accomplished by construction of a soil-bentonite to reduce seepage flow through the upper layer. This was complemented by a dynamic revetment covering teh entire height of the slope face to resist the effects of wave erosion and the ice sheet, and to support the oversteepened slope face.