Design of sustainable compacted soil blocks for raising dykes along the New Brunswick Fundy coastline

In Atlantic Canada, dyke systems are used extensively to protect the fertile agricultural land from being damaged by the saline ocean water in coastal areas. Without the 103 km of New Brunswick dyke systems, 14 500 hectares of land would be submerged by the Fundy tidal Fluctuations. The Shepody Dyke Rehabilitation project is required to ensure the land currently used for agriculture, transportation, and energy capture continues to be usable in the future. The original dykelands were constructed when the first Acadian settlements were built over 300 years ago. Due to continually rising sea levels caused by climate change, the dyke systems are currently threatened and require further development.

The Shepody dyke system construction has been a challenge in the past, due to variable site conditions and conventional construction methods requiring footprint extension onto valuable agricultural lands. As a result of this issue, a feasibility study on an innovative compacted soil block method to raise the dyke elevations was completed. By using pre-compacted soil blocks instead of conventional dyke construction methods, it will minimize the amount of heavy machinery required on site and keep construction within the existing dyke footprint. Based on the analysis of the proposed design, it was determined that the compacted soil block design meets the criteria established by the New Brunswick Department of Transportation and Infrastructure. The raised dyke height of 2.5m results in a final elevation of 9.6 metres above sea level. The stability modelling established a minimum factor of safety of 1.6 for the optimal compacted soil block mixture of 2% bentonite 98% natural soils by weight.