Soil, slabs and movement in Donnybrook VIC

Donnybrook shares its geology with Craigieburn and Kalkallo: predominantly Pleistocene and Miocene basalts with minor scoria and ash of the Newer Volcanic Group, overlain by Holocene alluvium along the creek courses. The basalt-derived clay is documented as likely to be subject to considerable shrinkage or swelling in response to moisture change, and parts of the corridor carry sodic soils prone to dispersion and instability. The Merri Creek and Kalkallo Creek alluvial corridors bring soft soils, erosion and flood considerations, and localised un-engineered fill has been flagged as a settlement hazard, particularly near existing and former dams.

Basalt-derived clay here shrinks and swells considerably with moisture change.

Sodic soils in parts of the corridor are prone to dispersion and instability.

Creek alluvium along Merri and Kalkallo Creeks brings soft ground.

Un-engineered fill near old and existing dams is a documented settlement hazard.

Your lot's classification comes from your own soil report, not from the suburb.

More about Donnybrook

Written by our local inspection team from work carried out in Donnybrook. Licensed building practitioners.

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Soil, slabs and movement in Donnybrook VIC: common questions

What is a sodic soil and why does it matter?

A sodic soil disperses when wet rather than holding together, which makes it unstable and prone to erosion. Parts of this corridor are documented as carrying sodic soils, and it affects how earthworks and drainage need to be handled.

Should I worry about fill on my block?

Localised un-engineered fill has been flagged in this corridor as a settlement hazard, particularly near existing and former farm dams. Your soil report and the engineering for your lot are what establish whether it applies to you.

Is the ground the same as Craigieburn?

Substantially, yes. The same mapped units run through Craigieburn, Kalkallo and Donnybrook, which is why the findings and the slab designs look similar across the three.