cachbefound: I got close enough to GZ to affirm that even if there's a cache somewhere around GZ, access to the area has been blocked by construction barriers. I'm guessing that those barriers are likely to remain for another six to nine months and as such I've decided to put this one to rest. It's had a good run and I thank all those who solved and visited it.
[cue background music - Grieg's Death of Ase]
https://www.youtube.com/watch?v=2aKxf1h5r4g