Muddy Merri troubles update
20th May 2019
Melbourne Water has been investigating the failure of constructed waterways on a new development. This failure, near Donnybrook Rd Mickelham was highlighted last year by Merri Creek Management Committee (MCMC) in our Muddy Merri Troubles Report. Behind the scenes, Melbourne Water have been working to rectify the problems exposed by this waterway. They recently provided a welcome update to MCMC on progress on this matter.
They have also acknowledged the widespread occurrence of problematic soils in the Kalkallo Creek sub-catchment of the upper Merri (west of the Hume Highway between Donnybrook Rd and Beveridge). All future developers will be required to address the issue of erosive/dispersive soils earlier in the planning/design process to avoid similar problems
In this photo, we can see the constructed section of Donnybrook Creek south of Donnybrook Rd, Mickelham, August 2018. The channel is eroding, rilling erosion can be seen under the jute matting (dark lines), the jute matting has been ripped apart by high flows, and the slopes above the jute matting are poorly stabilised and eroding.
Melbourne Water has met with the developer and consultant to discuss a number of rectification options including:
- Widening the waterway to reduce the velocities and shear stress in the channel.
- Constructing drop structures to flatten the longitudinal grade of the waterway.
- Replanting the waterway to create a vegetated core riparian zone and replace vegetation lost in the failure of the channel.
It is expected that rework will occur in late winter-early spring 2019, with re-planting to occur immediately after the civil works.