In-ground Reclaim water tank in a basement?

[Ben29]

I am doing a feasibility study for a client who wants to turn an existing building into a carwash.

The client wants to know if they can install the in-ground reclaim water tanks in the existing basement. They plan on using precast concrete tanks.

So basically they want to:
1) shore up the existing structure as required (provide supplementary framing to support the 2nd floor since we are removing interior bearing walls below)
2) remove existing first floor framing (wood joist bearing on wood beams, bearing on interior wood timber posts) (see picture below)
3) install the tanks in the basement,
4) install new interior cmu block bearing walls + footings
5) backfill the basement with stone (their suggestion)
6) form up the concrete trench for the wash bay
7) install a "structural slab" to support vehicle loading. Well, they want to do a "slab on grade" but I don't think a "slab on grade" would work here. Am I right?

You are probably going to tell me to get a geotech involved. But I am wondering if anyone on here has input about this approach?

 

[JStephen]

It sounds like there wouldn't be much of the original building left when they got done.
How do they get the tanks into the basement?
I'm assuming the first floor doesn't have big garage doors already, so you also have to remove the walls on front and rear?
Are there interior walls in the first story that would also have to be removed?

 

[LittleInch]

What's the basement floor made of / foundations. what soil type do you have there underneath it / water table?

Water tanks full of water do weigh quite a lot....

Basically sounds like they are planning to fill the basement in ( within some covered tanks) and build a slab on top of that?

Not sure why you don't just demolish the building and start again.



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