How much does it cost to dig a really big hole?

[hairykrishna]

This is larger scale engineering than DIY but this still seems like the best sub forum... What sort of order of magnitude cost would it be to dig a ~4m deep hole, say 4m wide by 10m long? Filling it back in afterwards so no disposal costs. Lets assume there's no services in the way and it's just earth.

We're looking at a new project at work that involves getting a very large pressure vessel into a sub-basement. I have no reference for what sort of cost we're looking at. In Birmingham if that makes a difference.

[hairykrishna]

Jonesy23 said:

Has anyone considered making the hole into the building at ground level then dropping through the floor instead?

It's an option. Unfortunately most of the floor is radiation shielding, so 5ft thick concrete, and not trivial to cut through.

Thanks for the input everyone. I realise it was a vague question so expected a range of answers! Hopefully I will update the thread when I get some more information. A different, very heavy, piece of equipment was moved into the building about a decade ago so there are detailed ground surveys. It's just working out who still has the info that's a problem at the minute!

[hairykrishna]

Thought I'd post a quick update. After looking at various options for how we're going to fit the new machine into the building we've decided that we need more space to do what we want to do well. Given that, it makes much more sense to construct a room in our proposed 'big hole' to house the accelerator pressure vessel permanently and use the existing structure for beam rooms. First steps are a detailed ground survey to check feasibility so that's being arranged at the moment.

[hairykrishna]

Vaud said:

What are you building, a particle accelerator?

Yes - it's an SF6 insulated accelerator surrounded by a big pressure vessel.

[hairykrishna]

oxford drinker said:

Just looking at a cost report for one of our jobs. 5m deep excavation at just £55 per cubic metre including disposal off site. But that's after the edges have been perimeter piled at a cost of £834,000....

Interesting! How big a perimeter?

[hairykrishna]

battered said:

As in sulphur hexafluoride? That's not trivial.

We already have an accelerator in the building that's a similar design so have plenty of experience with it.

[hairykrishna]

Vaud said:

OP - I think you need some professionals.

I was just trying to get some ideas of cost before we move to getting proper quotes- I'm not proposing to do it myself with a mini digger

We're getting a survey done next and then proceeding from there. I was under the impression that this was done a little while back for something different but nobody seems to know what happened to the results.

[hairykrishna]

Vaud said:

He has... "SF6 insulated accelerator surrounded by a big pressure vessel"

A particle accelerator uses sulfur hexafluoride(SF6) as an insulating gas for its high voltage terminal?

It uses it for the whole accelerating stack in this case. Pictures of the base of the accelerating stack with the vessel open, and the pressure vessel itself, from our old accelerator;






New one is fairly similar.

[hairykrishna]

GreatGranny said:

OP, so would that mean building a similar spec basement to the existing building? ie. 5ft thick RC concrete walls and presumably the ceiling as well?

Who have you got involved so far?

Just someone to do a ground survey or structural/geotechnical engineers as well?

Much lower spec than the existing basement. The shielding requirements for the accelerator itself are much lower than those needed for the target rooms.

[hairykrishna]

Thought I'd revive this thread. Our proposed hole got a lot bigger. It's now going to house a 20mx5m room with the accelerator in it. Returning to the point of the original question i.e. cost of digging it out, current best guess from my QS is ~160k+VAT.

Current total budget is...a lot. I'll update if we get through planning for the above ground stuff and the bugger actually gets going. Hopefully I'll eventually have some photos of my giant hole to share

[hairykrishna]

We dug a giant hole. Quote a lot of concrete being poured back into it at the moment.
|https://thumbsnap.com/yxoY8Wwn[/url]

Edited by hairykrishna on Wednesday 15th June 12:35

[hairykrishna]

The 'hole digging' costs were about 200k including some sheet piling. It was a fair bit bigger than I originally talked about though. The total build is roughly 4 million all in but that includes a couple of 300kW chiller plants and a bunch of other specialist M&E.

[hairykrishna]

ZymoTech said:

Ah, I think I know where that hole is. There was an occasion last year when I called into the building next door (where the brick wall is on the left hand side of the picture) to collect some equipment from the PET lab to take back to our department. There was a great big excavator, with a great big breaker attachment, sitting at the bottom of the hole nibbling away at some concrete foundations. Every "jugga, jugga, jugga" it was generating was vibrating through the building. And it was making a bit of noise. Peace and quiet inside ? No chance.

That's the building I'm based in - I do a lot of work with the PET lab.

Our existing accelerator control room was just on the other side of the wall from where it was nibbling away. It was seriously loud

[hairykrishna]

Halmyre said:

This all sounds very suspicious. OP, please advise if you have any of the following:

1. Metal hands
2. Fluffy white cat
3. Submersible laboratory
4. Grey collarless suit
5. Megalomania

Perhaps a mild case of 5? Plus a propensity for maniacal laughter.

[hairykrishna]

General Price said:

Nice,did you need to pay extra for the rebar and concrete or was that included in the £500?

There are 60 tons of rebar just in the floor slab. We did not get change from £500

It was amazing how quickly a dude in a 13 ton digger can chop out a giant hole. The limiting factor was how quick they could get the dumper lorries in and out - I think we were doing about 40 in a day. It was a lot of earth.

[hairykrishna]

Muncher said:

That was kind of the point in my original post, the digging bit alone is quick!

Last year we had about 900 cubic meters of soil stripped, sifted of debris and neatly piled up in no time at all.

Yes - took about a week and a half once he got into it. It was quite interesting to watch, as it was right under my office window. Basically dug right down then built himself a ramp to get back out again!

[hairykrishna]

Probably the roof formwork. 23 lorry loads of concrete in one day was nice.

|https://thumbsnap.com/zrtRUmjT[/url]

|

[hairykrishna]

Realised that I never posted any pics of the finished bunker so here's a few. If anyone's got a big building project I'd recommend GF Tomlinson. They were my main contractor and were excellent.

The accelerator arrives in the country at the end of the month so it's exciting times. We should be up and running late summer.

[hairykrishna]

[hairykrishna]

Thought I should update again. Lots of big bits in - it fits! Waiting on lots more parts over the next few months before we throw the big switch.