Stone Coal Bunker - Raised Herb Garden (Conversion)

Hi,
My wife and I have recently moved into an 1830's cottage and in the front garden, by the gate which leads up and into the main area, is an original stone-built coal bunker. The bunker currently has a wooden lid attached and was (up until we moved in, still being used as such).

We would like to convert this into a raised herb garden but what is the best way to do it. See pics for the bunker (apologies for the poor pics - rubbish camera!)

Obviously we could just fill it up but would there be drainage issues?
(There are no holes around the bottom of the bunker - no meaningful ones anyway)

thanks for your help
Nigel & Rachael

 

Hi JWK, The bunker is about waist height, made of stone and cemented in. the bottom is concrete. It would mean drilling through the heavy thick stones at the base of the bunker.

I was trying (hopefully) to avoid having to do that and maybe using a lot of similar stones placed in the bottom with smaller stones on top then filled with soil?

 

A simple experiment JWK, good thinking! I'll try that any see what happens.
I'm just baffled I didn't think of doing that myself

 

I think that would make an awesome raised pond personally.

 

not a bad idea Jane, it's just whether the walls would hold that weight of water...and if I have the patience to look after it!

I tried the water test by the way JWK...the bucket full ran out of a few minor gaps around the bottom so I guess it should be alright...however I end up using it!
thanks

 

If you line it with pond liner and maybe a bit of sand at the bottom under the liner it should be fine.