This page explores the possibilities for removing, altering or covering the concrete sections of the creek, with the aim of eventually naturalising the entire length of the creek. Where possible, costings have been included.
1. Concrete Removal
Concrete would be completely removed and taken away. Rocks would be used to replace the concrete, to create a semi natural state that would be attractive but resistant to erosion. Estimated cost per km: million(s)
2. Concrete “Disruption”
This would involve breaking up the concrete in some way, in order to “let nature take its course”. Eventually grass and trees would grow through the broken concrete and create a more natural appearance, however the creek would maintain its regimented look, with straight lines and regular curves instead of a random path. One possible suggestion, from Prickly Pear:
Estimated cost per km: 1000s?
3. Concrete Cover up
Would involve leaving the concrete in place and covering it up using:
· Water – create small concrete dams every 100m or so, to raise height to cover concrete base, then put down wire trestle, concrete reinforcement steel sheets, gravel holders etc on the diagonal side sections, to allow grass etc to grow down from banks.
· Rocks – Either by breaking up concrete first, or applying some sort of grid of wire, then place large or medium size rocks to cover concrete. Eventually silt would get caught in rocks and vegetation would grow.
· Pebbles, clay, dirt etc
In all cases many trees and shrubs would be planted on slopes to soften creek and help prevent erosion.
4 “Two Creeks”: high and low flows
The cost of removing the concrete would be tens of millions of dollars, the resulting more natural creek would be more susceptible to flooding, and neighbouring residents would be very resistant to any increased flood risk. Additional safety concerns about the creek at times of high flow would create community and council resistance.
The solution? Two Creeks! One below ground in two barrel drains to take high flows, one above ground that would be natural in appearance that would have a constant low flow. The diagram below shows how the system would work:
In order to separate the two creeks, reservoirs would be needed every kilometre or so down the creek, these would have spillways so high flows would travel underground and low flows would travel above ground.
This sort of scheme would have a number of advantages:
A “chain of Ponds” creek could be created above ground with constant low flow of water, close to ground level, with minor risk of flooding and all sorts of possibilities for creating natural habitats.
Melbourne Water would get to preserve their asset, the risk of flooding would be diminished to the satisfaction of neighbouring residents, and the dangers of above ground high flows of water would be eliminated.
Estimated cost per km: ? millions