I have just spent the afternoon trying to remove the foundations of an 8 x
12 ally greenhouse with/for a neighbour.
Three rows off well cemented solid brick below soil level was OK and what we
half expected, but it was on top of a foundation of a foot wide and at least
that or more* thick of reinforced concrete. (We dug down beside it at least
a foot and didn't find the bottom)
OTT for a light aluminium greenhouse? We thought so.
We had to leave the concrete, it would need serious builders machinery to
remove, and he will just extend his lawn and grass over it, after all, it's
three brick down below soil level.
The veg patch he was going to have there will have to go elsewhere.

--
Regards
Bob Hobden
17mls W. of London.UK