Converting coal bunker to Koi pond?

[footprints]

Hi All, can I have a bit of advice please?
My Daughter has a disused coal bunker and wants to turn it into a pond (with liner) now the existing has the back and one side against the garden in single skin brick, with a concrete base.

The front is missing and the other side butts against the garden steps. The side against the steps is mostly supported but the last 18" or so rises above the steps. They want Dad to help brick up the front and part of the side that is against the steps.

Will a 9" wall at the front be strong enough and maybe just the top section of the side in single brick be sufficient? Any chance single brick all round would work?
My guess is the pond will be about 6' long 3' wide and 3' deep.
That's around 54 cu ft of water and as I recall from those far off apprenticeship days, there are 6¼ gal to a cuft so looking at about 340gal (3400 lb of water) at least, got a bad feeling about it myself but maybe I'm just being over cautious.
Thank you for any help.

 

[Handymanjo]

How are you going to tie all the sides of the coal bunker together ?
The water pressure will be too great and the joints will fail and damage the liner.

 

[footprints]

Thank you for the reply Handymanjo.

Wall ties were suggested.

 

[endecotp]

This is very much like the calculations done by civil engineers for retaining walls. See if you can find a student who will work it out for you in exchange for a pint . Toppling forces can be quite large (and contrary to our intuition). My back-of the-envelope calculations say that a 9 inch thick wall is nothing like thick enough to withstand the toppling force of 3 feet of water - but I'm ignoring any strength provided by the corners, or the junction with the ground. If I were you, I'd investigate other ways of holding the sides in - like how "IBC water tanks" (google it) use metal bands to hold themselves together.

 

[big-all]

how toxic is coal dust to fish ???
just a thought

 

[footprints]

how toxic is coal dust to fish ???
just a thought

Good point but has been out of use for donkeys years and would have a liner.

I suppose she could bung some salt in and keep these!

http://britishseafishing.co.uk/coalfish/

 

[Nige F]

Looks like a load of pollocks.

 

[Handymanjo]

Pollock are not fresh water fish ?
Pond needs to be a lot deeper for them.
You will need one hell of a liner !
The pressure on the corner joints will be unreel.