Project profile.

Brief:

Contractors: VEC Civil Engineering, Vos Constructions.

Engineering Edge were engaged to design, document and certify the concrete flood levee transition walls at 6 locations (900m of wall) along the banks of the North Esk River to protect Inveresk from flooding to a 1 in 200 year flood level. The design was on soft silts to depths of up to 26m with flood heights up to 3m and underflow potential from the soft silts. Along with this was 600m of combined pedestrian and cycle way including 300m of elevated precast prestressed concrete bridges to enable pedestrians to view the river over the top of the wall.

The levee wall consists of vinyl sheet piles to stop underflow, driven steel piles to support the wall, precast concrete panels with textured finishes for aesthetics and a number of gate structures to enable access through the wall. Engineering Edge’s design resulted in savings of over $10M on initial budgets.

challenges:

The soft silts of Invermay required a piled flood levee wall to resist the vertical and horizontal loads, along with an underflow cut-off solution to remove potential for piping failures under the wall. The soft ground around the wall also made access for construction equipment difficult.

the rare innovation:

A buttressed and precast concrete panel solution was developed with a vinyl sheet pile underflow cut-off wall incorporated. The vinyl sheet piles are designed to slip vertically within the footing to allow for the drawdown to not damage the piles from the long-term consolidation of the silts.

key benefits:

A high quality finish to the levee walls, along with stencil imprints has made the flood levee a welcoming addition to the landscape rather than being an eyesore. The huge reduction in budget and the increase available land also provided great benefit.