Containers and flood risk on the Richmond — what steel can and cannot do

Why we are writing this at all

In late February and early March 2022 the Wilsons River at Lismore reached about 14.4 metres — the highest level ever recorded here, over the levee and well past the 1974 mark. It went through the CBD, through South and North Lismore, through Coraki, Woodburn, Broadwater and a long list of places along the Richmond, and through thousands of homes and businesses. Neighbours took people off their roofs in tinnies. Four years on, this district is still working through what that did.

We sell shipping containers here. A large share of what we deliver into this valley is part of a rebuild, a repair or a decision somebody made afterwards about where their things are going to live. It would be very easy to write marketing copy that lets people infer something about steel and water that is not true. We are not going to do that, and this page exists so that nobody buys anything from us on the strength of something we implied.

What "watertight" actually means

When we say a cargo-worthy container is checked wind and watertight, we mean a specific and quite limited thing. The roof does not leak. The corners do not let daylight through. The door seals seat well enough to keep weather out. It is a test done from inside with the doors shut, looking for light.

Every part of that is about water arriving from above. Rain, wind-driven rain, water running off a roof. That is the whole scope of the claim, and it is a real and useful claim — a good container will keep a shed's worth of tools bone dry through a Northern Rivers wet season.

Floodwater does not arrive from above

It rises. And the first thing it reaches on a shipping container is the bottom of the door seals, which sit at the very bottom of the door aperture and are the least sealed part of the entire box. A door seal is designed to shed rain running down a closed door. It is not a submersible gasket and it was never intended to be one.

So water gets in. And here is the part that surprises people: once it is in, a container is extremely good at holding it. You have a welded steel box with a marine-ply floor and one drain path that is now under water. Things that were dry at the start of the event are sitting in it afterwards.

The buoyancy problem, which is more serious

An empty or lightly loaded shipping container is buoyant. It is a large sealed volume of air inside a relatively light steel shell, and in enough water it will float.

A floating container in moving water is several tonnes of uncontrolled debris. It can take out a fence, a wall, a vehicle or a smaller structure, it can block a culvert or a bridge opening, and it will end up somewhere other than where you left it — potentially on someone else's property. This is not a theoretical risk in this catchment and it is the reason we raise it with people siting containers on low ground.

So what does a container actually offer here?

Three real things. None of them is a promise, and all of them are worth having.

1. Height — you choose where it sits

This is the big one, and it is entirely within your control and costs almost nothing to use. A container is not built into the ground. You decide what it stands on. Sited on the highest useable ground on a property, on a built-up pad where the site allows, clear of the drain lines and the low corner where water gathers, a container is dry lockable storage in a place where a great deal else is not.

The reference point most people here use is the level the water reached in 2022 on their own block. That is a far better guide than any general rule, and it is knowledge that only the property owner has.

2. Mobility — it can be moved

A shed cannot leave. A container can. If there is warning, and the truck access is still clear and safe, a container can be lifted onto a truck and taken to higher ground. Two caveats and they matter: warning is not always available, and access roads flood before properties do, so the window is often shorter than people assume. It is a genuine option rather than a plan.

3. Dry, lockable, secure storage while a rebuild runs

This is the use that has mattered most in this district. A house being stripped back to frames needs its contents somewhere dry, lockable, and on the owner's own property rather than in a storage unit across town. A container does that job better than anything else at the price, and for a lot of Lismore and Coraki households that has been the entire reason for buying one.

Practical siting advice, since you are here

• Height first. The highest useable ground on the block beats the most convenient spot, every time. Build the pad up if the site and your budget allow it.
• Away from the flow. Clear of drain lines, table drains, creek lines and the corner where water gathers in ordinary rain.
• Proper pads. Hardwood sleepers or concrete under the four corner castings, on compacted ground. Uneven settlement twists the box and stops the doors sealing.
• Fall away from the doors. Set it so the door end is not the low end. A threshold sitting in a puddle after ordinary rain is a threshold that will rot the floor edge over years.
• Keep the access open. A container you cannot get a truck to is a container that stays where it is, permanently. Think about that on the day you choose the spot.
• Do not store the irreplaceable at ground level on low ground. Photographs, documents, things that cannot be bought again. Shelve them high inside, or keep them somewhere else entirely.

Things we will not say

We will not describe a container as protecting a property from flooding. We will not attach the word "proof" to anything we sell in connection with water rising, because it is not true of a shipping container and using it would be a way of getting a sale without stating a fact. And we will not talk about the 2022 event as an opportunity.

What we will do is answer the question honestly when you ring, tell you where on your block we think a container should go, and say so plainly if what you are describing needs an engineer, a builder or your council rather than a steel box.

If you want to talk it through

Ring 02 6622 1322. It is answered by someone who knows this valley and has delivered onto a lot of these blocks. Bring the address, tell us what the ground is, and tell us what you are actually trying to protect — that is a much more useful conversation than a size and a price.