HEALESVILLE SITE CUT & FOOTINGS, 2.5M DEEP

One and a half metres is the number to remember. Under Victoria's OHS Regulations, a trench or shaft excavated deeper than 1.5 metres counts as high risk construction work, which means a Safe Work Method Statement has to be prepared before the work starts. The Healesville cut was 2.5 metres, so comfortably over. Depth is not the only trigger though. If someone is entering the excavation and there is any risk of ground collapse, the sides have to be positively supported, benched, battered or shielded regardless of how deep it is.

For a trench 1.5 metres or deeper, yes, in writing at least three days before work starts. There is an exemption a lot of people have never heard of. Notification is not required where the trench is part of building work covered by a building permit that is in force under the Building Act 1993, which covers most residential builds. We will tell you which side of that line your job sits on before anything gets booked in.

A slab on ground sits on the dirt. A suspended slab spans between footings, piers or walls with a void underneath, which is how you get a level floor on a block that is not level. For us that means footings go deeper and in specific set out positions rather than in one general trench, and on this job they were dug off a platform already 2.5 metres down, so the depth and the set out compound each other. It all comes off your engineer's drawings, not off our judgement on the day.

Because of where the dirt could go, not how much of it there was. On the Silvan job 650 cubic metres came out and every bit of it stayed on the property, moved across the block ready to level another area. In Healesville there was no room to move and it all went out the gate, seventeen loads of it. That is the single biggest thing that moves what a cut costs you. Before we price a block we want to know whether there is anywhere on it that wants filling, whether the ground there will take it, and whether we can get a machine between the two.

Not something we settle by eye on the day. Benching and battering have to be designed by a suitably qualified person, usually a geotechnical engineer, and that design has to account for the soil type, the moisture content of the soil, the height of the face and anything loading it from above. Faces get battered back to the angle of repose, and anything steeper than that needs a documented geotechnical analysis before digging starts. Wet ground changes the answer, which is why the same face can be treated one way in February and another in September.

This got harder recently. Victorian Resources Online, the free state map most people used for soil and land information, was decommissioned in July 2025. The Soil and Land Directory has moved to the Public Record Office of Victoria, and the rest of VRO is not expected to be downloadable there until early 2027. For a shallow job you can usually manage without it. For a 2.5 metre cut you want a soil test or a geotechnical report anyway, and that is what the excavation rules effectively assume is sitting behind the design.