Excavations for pool

Ask questions about buying, installing and maintaining a swimming pool/pond in France.
Mike

Re: Excavations for pool

Post by Mike »

Andy72 wrote:
Sun Apr 28, 2019 9:41 am
Hi, Wifey wants one of those semi inground pools that need a hole digging of around 80cm depth. Has anyone installed one of these? Did you hire a mini digger or get someone in to do the job? The pool she wants is a 9x5 hexaganol design so my maths tells me that's about 40 m3 to dig out and spread around the field. How long would that take a person with a digger to do?
Can't get a 9 x 5 hexagon to work no matter how I manipulate the figures, now if you mean a 9M point to point x 4.5M side, at 0.8M deep that works out to be 42.088M3, it would take longer to set out than it would take for a digger to dig it, one way would be a post hole borer at the centre and one at each point, loosen the areas that need it with the borer and hand dig, I don't recommend doing this by hand, you would be crocked up for days afterwards, ask a local farmer if he has, or knows anyone with a digger, you will still have to set it out, use profiles set back from the dig so its difficult to drive over them, also make up a traveler to measure the depth from each profile.

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Andy72
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Re: Excavations for pool

Post by Andy72 »

Hi, revisiting this thread now as we are in the process of buying one rather than talking about it. For the concrete slab, what size thickness would be required for a 9x5x1.4 metre above ground pool?
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Re: Excavations for pool

Post by Hal »

On the basis that a 100mm slab can take around 1.5T per sq cm, 100mm should be ok especially if the ground underneath is firm. If not, then maybe 150mm. Make sure you have decent re-inforcing material in the slab.

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Re: Excavations for pool

Post by Andy72 »

Thanks. The soil is clay underneath and very firm. I'll put some mesh sheets in too so I'm guessing 100 mm should be ok.
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Re: Excavations for pool

Post by Mike »

I don't think concrete technology has changed much since my days as a structural engineer, we used to instruct the contractor to take 100mm cube samples for crushing at seven, fourteen and twenty eight days, if you had a specification of 300kg of cement/M3 in ideal curing conditions you could get a result of 50N at seven days.

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Re: Excavations for pool

Post by Noisette »

However firm the ground, the basic problem here in France is the quality of the hardcore. Depending on your local stone, there's calcaire, limestone ranging from huge chunks to dust. Appalling stuff - however much it's compacted, it becomes a sludge when wet and the slab cracks or sinks. Then the maçon's solution...loose river gravel. Can't be compacted at all. When you compare that with the traditional compacted hardcore used in the UK, it's a joke.
Bear in mind drainage, Andy. When you've got a big hole on clay, it acts as a sump, so think about putting French drains around it, or using a puits de compression (sorry, don't know what that is in English) to take excess water away from the hole.
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Re: Excavations for pool

Post by Mike »

Can you get MOT type 1 or 2 in France, they must use something similar under motorways?

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Re: Excavations for pool

Post by Le Démerdeur »

Yes, its called tout venant literally "all coming" meaning you get what is available in the area, its a mix of fine and course material like MOT or hoggin, around here they use road scalpings mixed with other stuff, cheapest stable fill material.

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Re: Excavations for pool

Post by Annabelle's Papa »

I wouldn't bother with a concrete base as you have clay soil, did our above ground pool over a weekend 9 years ago, we have clay, cleared the area so it was flat and then spread a fine sand and then a felt liner supplied with the pool and 9 years later looks as good as new, honestly. It was a Trigano brand available in the UK and France, wood effect metal sided pool, looks the business. Ours it 5m round but they do different shapes, ours cost €800 with the filter and pump. Have a look at their website or you can sometimes get a brochure from your local DIY shed.

Best I could find but looks like a bargain !

https://www.amazon.co.uk/14ft-Power-Ste ... G0ZVWBDQX8

We have been very lucky this summer with the weather in Brittany, only had to heat the pool 5 times to maintain an average of 28 degrees over 9 weeks of use. The smaller the pool the less energy to heat is worth noting, ours is heated by a stainless steel 28 kw log burner (cost £350).
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Re: Excavations for pool

Post by timbo »

I put about 100mm of dry mix concrete under ours, but the best part was 40mm of extruded polysyrene slabs on top of the concrete, really nice to stand on in the pool, and no risk of stone punctures.

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