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Sizing Soil Skip Bins

News > Sizing Soil Skip Bins

Sizing what size of skip bin you need for soil can be a little bit tricky to calculate (guess, guesstimate or even estimate). The trickiness is due to the condition of the soil and whether it is heavily compressed from being in place for years or whether it has be recently airated when it was dug up or disturbed in any other way.

Sizing Soil Skip Bins
Sizing Soil Skip Bins

The surprising fact is that when you dig soil out of the ground it can almost double in volume. Now it isn't really the soil that doubles in size it is actually more the space that is inbetween the peices of soil that take up all the additional volume.  This is very similar to what happens if you take a stack of bricks and throw them into a skip bin. In the stacked bricks there is very little air between the bricks (if not almost none). Throw the bricks into a skip bin and there can be are much space between the bricks as there was volume of bricks.

The bottomline to the soil "expansion" is that if you dig a square hole in the ground, say 1 meter deep, and 1 meter across in both directions then the volume of the hole would be 1 cubic meter, but the volume of the soil that had been removed would be more like 2 cubic meters.  If you don't beleive me try it for yourself (no, no, save your effort I am only having a little joke. Just beleive me, its true).

So the simple way to work out what size skip bin you need to get rid of soil is to calculate the solid volume of soil in palce in the gound and then double it for the likely expansion.  This isn't too hard as it is just a case of calculating the volume of a box, or a series of boxes adding them together and then doublng it.

Soil In 4m Clean Fill Skip Bin
Soil In 4m Clean Fill Skip Bin

We often get customers calling up and asking about gettting rid of soil and saying how many tonnes they need to get rid of because the builder said they needed a 3 tonne clean-fill skip bin. Well there is no such thing as a 3 tonne bin. In fact bins are rarely rated by what weight of material they can hold because it is the density of the material that determines what the weight of material would be in a 3 cubic meter bin.  And the weight of soil or clean-fill will vary from loaction to location and day to day. If your soil ic full of clay then it will have a greater density than if it is good loamy soil. And if it has rained recently then the density (weight per cubic measure) will be greater as the soil will soak up the rain like a sponge.  So the important thing to remember is that the right way to selected a bin is by its volume because the volume of a skip bin is static. It doesn't change when it has rained of been left out in the sun. The density of soil, sand or any other type of clean fill can change as the weather dries the material or fills it with water.   

So if you have a pile of soil that has just been dug up you don't need to double the volume of the material that is piles up if you have estimated the volume of the pile. You only have to be careful  when the pile has been in situ a long time because it can become compressed as a pile. And not just because of people walking on it or children playing on it. Just the impact of the weather will change the pile. Rain will cause material to be washed down through it, filling the small spaces within the dirt pile.  Sun, cold wind and rain alll can have similar effects, causing the pile of clean-fill to appear to "Shrink" when in fact it is just consolidating. Then when it is dug up again to go into a clean-fill skip bin it will expand again.

  • Authored By:Stephen Shergold
  • Published:14/03/2018