Nervous as to what might be under the concrete

[MortarThePoint]

Hope everyone is having a nice break over Christmas / New Year. Thank you to those who might be working.

 

We are clearing our site ready to get started in the new year. Part of this involves demolishing some ex commercial buildings that are in the way. The largest (300m2) was built in 2010. As there were previously old sheds on the site (seen in some aerial pictures) I am nervous that there could be fragments of asbestos roof sheeting underneath the concrete floor, and worse could be stuck to the concrete. Sending asbestos contaminated concrete to landfill is eye wateringly expensive. If the concrete is 150mm thick and all had to go it would be 45m3 and cost about £13k, of which about £10k is landfill tax. Businesses would be able to reclaim that tax, but not us selfbuilders as far as I can work out.

 

I don't know if the problem exists, but the risk is pretty stressful and I need to be prepared if it does occur and we end up under pressure to make decisions (plant on site etc). Any thoughts as to how to reduce the quantity of concrete would be greatly appreciated. There are some companies that undertake the treatment of soil contaminated with asbestos fragments (Provectus and Biogenie) and I think that involves hand picking at their facility. Bonded onto concrete is a different matter though. I have thought about 'planing' ~120mm off the concrete to thin it before lifting and therefore reducing the quantity to ~9m3 (£3k). I had a quote for water cutting and it was 10s of thousands so not viable.

 

Any thoughts would be gratefully received and hopefully provide some sleep filled nights. Hopefully won't be needed but pays to be prepared.

[Russell griffiths]

This is by no means the correct advice, but does it need to go off site, do you have enough land to do other things with it ?

how about hardcore under a detached garage. 

 

A person i know ended up with a lot of large concrete that he didn’t know he had, so dug out another area on site and buried it. 

 

Under the driveway ?  

 

As I said by no means correct advice, but sometimes you just have to do what you have to do. 

 

Reading back through your post, my friend had far more than 45m that should be 3 truck loads, so reasonably easy to re,distribute under a driveway. 

Edited December 26, 2019 by Russell griffiths

[MortarThePoint]

Thanks Russell, but I'd be keen to get it off site. As I understand it, the 'rules' do allow you to use such material on site if your landscaping plan requires raising levels and it is then suitably covered by clean soil.

 

 

[joe90]

I buried lots of concrete under places like patio, paths and  drive etc. Better than paying to have it taken away then replacing it with purchased stone.

[MortarThePoint]

I'll crush and reuse all the concrete I can, but if any is contaminated with asbestos it would need to go.

[Russell griffiths]

1 hour ago, MortarThePoint said:

I'll crush and reuse all the concrete I can, but if any is contaminated with asbestos it would need to go.

Not necessarily, it’s actually fairly safe if not disturbed in a way to make dust, I would be happy to bury it on my site if I new it would never get disturbed in the future. 

[joe90]

If you pay to get rid of it, it will only be buried somewhere else!

[Mr Punter]

I think if it is cement bonded and the existing slab has to be removed you may be best burying it under the new slab.  It is entirely harmless in this situation and far more damaging if removed / planed down and deposed of elsewhere.

 

I think you may be worrying about nothing, although if you do discover any materials that are unknown, get them dealt with professionally and assume they are higher risk asbestos.

[MortarThePoint]

Thanks guys. We will use professionals for all of this, but I wanted to work out if there was a way of reducing the amount that went to waste if the issue were to arise. Fingers crossed!

[Sue B]

We buried bits of asbestos under a large pond in our first house.  Even if the new owners fill in the pond, they will probably just fill it with earth and not break out the bottom so perfectly safe.

[Barney12]

Another vote for leaving it on site. You are likely to cause way more environmental impact by removing it from site. 

The key factor is finding a sensible (and most likely smaller and local) ground works contractor who is going to be sensible. If you use a big firm you’ll likely get a machine operator who just ticks the boxes and a contracts manager who’s job it is to maximise the price on the job. 

 

I’m not ignoring the risks of asbestos but as others have said if it’s sheeting encased within concrete then the risks are incredibly minimal. All H&S starts with a risk assessment and the method statement follows with actions that are practicable. 

[ToughButterCup]

On 26/12/2019 at 10:20, Russell griffiths said:

This is by no means the correct advice, but does it need to go off site, do you have enough land to do other things with it ?

how about hardcore under a [...]

 

Could not agree more. If your site has a slight slope your scope for losing it is greater.

[scottishjohn]

 once you involve professional waste people or get bore holes drilled to check for contamnated ground --then they are bound to report to council  if they find pollution

 AN EXAMPLE

an old gas works in newton stewart was closed and flattened --this was the last working coal gas plant in mainland uk - should have been kept as a tourisit attaraction 

 any way it flattened - and site was sold -supposedly the soil polluted from 150 years of gas prodcution was removed

 new building put up

 15 years later same site was sold to ALDI 

by now laws had changed and council insisted on bore hole  investigations,even though it had not beeen gasworks for years 

 RESULT

 job stopped for 6 months while hundreds of truck loads of subsoil was removed from below the recently built founds of the other building,down to the level of the river next to it --about 10m

.If this had been a private site i think they mgiht have got it done quick and no council checks 

   so beware if its brown fieldsite  and its use in past was something that could pollute -then they copuld insist on ground checks once you open it up ,or even before at planning stage 

 So open it, tell no onne of any doubts about pollution  and get it filled in again quick .

 

 

[MortarThePoint]

Thank you for all the suggestions. Hopefully it is a bridge we won't have to cross. We have already been through all the site investigation phases and there is some old road planings that need to be dug out anyway, other than that all good so far.