One of the main challenges in the project is that water has to flow every minute of every day during construction, and because the new gully will be in virtually the same place as the existing one, the water will need to be diverted a couple of times over this period. Also, certain parts can only be built during the summer months when the water flow is lower, which makes it vital that everyone stays on schedule.
To be able to redirect the water to the bypass pipes during construction of the new concrete gully, the first stage is being built furthest upstream, where a water inlet for the bypass pipes is being installed. To manage the water during construction and the groundwater in the permanent phase, the plan is to cast a thick sealing plate. The inlet will then be cast onto the sealing plate in order to hold the structure down and counter the upward-lifting water pressure.
In the early stages, the lower part of the river gully and a new bridge called Diagonalbron will also be built. This section will then connect to the existing part of the Mölndal River.