just line it with pond liner then put whatever you want in
Then cover with lye and earth
( glued eel /questions/questionsyoudliketoask/post1648081, Sat 7 Apr 2012, 14:32, archived)

I reckon it'd be a dead good place to store some concrete lumps

( Theoban This isn't what I ordered..., Sat 7 Apr 2012, 14:41, archived)