Engineering solution for ‘salt bog’ city

Instead of reclaiming land back from the sea, it is bringing water inland to create an ecologically rich marine waterway city.

The city is a commercial and residential development that will, on completion, house over 100 000 people. Itis built on land that was mostly classified as ‘Sabkha’, a salt bog. What the developer proposes is to transform this land into a sustainable, ecologically rich environment by expanding the two existing intertidal creeks into inland lagoons, building self sustaining islands on these waterways to create wildlife habitats and planting mangrove to protect the new ecosystem. The biggest challenge was to ensure sea tides could flush the system, oxygenating the water to ensure survival of the ecosystem and prevent pollution.

The unique engineering solution was a series of six massive tidally powered gates that allow for the tide circulation around the development. These gates were built into specially designed culverts which provide the main passage of the sea water to the lagoons.

All six of the 10 ton, 50m2 culvert gates were supported by hinges fixed with 25mm Macalloy tension bars. To ensure these huge tensile loads were evenly distributed back to the concrete structure, a strong and durable non-shrink grout had to be used.