After a long wait, we managed to get a detailed quote from a local excavation contractor (two other companies only provided very general prices per cubic meter; all are so busy that new projects are not attractive).
The earthworks, including piping, amount to over 34,000 € net. Demolition of a small garage and the old concrete driveway are also included, costing "only" 5,500 € net.
The company would crush the demolition material (concrete, bricks) to less than 70mm (2.8 inches) and reuse it on our property beneath the topsoil. If we have the material removed, it costs several thousand euros more.
The idea of having fill material beneath the soil makes me uneasy. However, I cannot think of any tangible, rational reason for this.
Or is there one? Could concrete or bricks contain harmful substances, for example?
Thank you for your thoughts on this!
The earthworks, including piping, amount to over 34,000 € net. Demolition of a small garage and the old concrete driveway are also included, costing "only" 5,500 € net.
The company would crush the demolition material (concrete, bricks) to less than 70mm (2.8 inches) and reuse it on our property beneath the topsoil. If we have the material removed, it costs several thousand euros more.
The idea of having fill material beneath the soil makes me uneasy. However, I cannot think of any tangible, rational reason for this.
Or is there one? Could concrete or bricks contain harmful substances, for example?
Thank you for your thoughts on this!
Regarding harmful substances, I wouldn’t be too worried. What bothers me more is that when digging in the garden, you hit a layer of rubble already after 20cm (8 inches). For example, if you want to plant a tree or some shrubs. That’s probably not ideal for their root systems either, although it depends on the amount and density of that material.
It’s probably not suitable for excavation under the driveway or terrace, right?
It’s probably not suitable for excavation under the driveway or terrace, right?
Google “LFU Bavaria FAQ excavation spoil.”
Use your own excavation spoil. It can’t be more contaminated than what is already there.
There was once a discussion that soil excavation spoil should no longer be reused on the same property. That idea has been dismissed.
What you do with the construction debris is your decision.
The worst contamination in both samples we tested was chloride, classified as Z1.2.
Most were classified as Z0.
It’s difficult to assess building materials from the 1940s and 1950s since they used whatever was available at the time.
All companies advised us against backfilling with this material, except those who offered crushing services.
What I can’t evaluate are the contamination levels themselves—how to interpret them and what kind of risk they represent.
Most debris is allowed to be disposed of in quarries or used as recycled construction (RC) material in road construction. So it probably isn’t highly toxic.
What would bother me is if you hit the debris just below standard digging depth.
If you’re only planting something like radishes, it might be okay.
Use your own excavation spoil. It can’t be more contaminated than what is already there.
There was once a discussion that soil excavation spoil should no longer be reused on the same property. That idea has been dismissed.
What you do with the construction debris is your decision.
The worst contamination in both samples we tested was chloride, classified as Z1.2.
Most were classified as Z0.
It’s difficult to assess building materials from the 1940s and 1950s since they used whatever was available at the time.
All companies advised us against backfilling with this material, except those who offered crushing services.
What I can’t evaluate are the contamination levels themselves—how to interpret them and what kind of risk they represent.
Most debris is allowed to be disposed of in quarries or used as recycled construction (RC) material in road construction. So it probably isn’t highly toxic.
What would bother me is if you hit the debris just below standard digging depth.
If you’re only planting something like radishes, it might be okay.
Thank you all for your contributions.
@haydee thanks for your link! And yes, I wouldn’t have any concerns about reusing the excavated soil either: our soil analysis came back quite positive, with no toxic traces found.
I’m still very uncertain about the rubble: on one hand, a downside for the reasons you mentioned (and the uncertainty about whether it is really 100% safe), on the other hand, an advantage because of about €3,000 savings (which could potentially affect our future garden life. Hm...)
@haydee thanks for your link! And yes, I wouldn’t have any concerns about reusing the excavated soil either: our soil analysis came back quite positive, with no toxic traces found.
I’m still very uncertain about the rubble: on one hand, a downside for the reasons you mentioned (and the uncertainty about whether it is really 100% safe), on the other hand, an advantage because of about €3,000 savings (which could potentially affect our future garden life. Hm...)
I would consider using gravel for the terrace and driveway. Purchased gravel is essentially the same. You can ignore the scare tactics here.
If the ground only needs to be raised by 40cm (16 inches), I wouldn’t put gravel in there. You can get soil for free from the next new build anyway. Put 20cm (8 inches) on top, then the topsoil goes on afterward. Gravel doesn’t belong directly under the topsoil.
If the ground only needs to be raised by 40cm (16 inches), I wouldn’t put gravel in there. You can get soil for free from the next new build anyway. Put 20cm (8 inches) on top, then the topsoil goes on afterward. Gravel doesn’t belong directly under the topsoil.
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