The next question is about what you intend to bury?
If it is big enough for you to use a backhoe it gets even easier.
You will need signs and barricades then, but your visibility is so high that you become invisible.
Just be careful to not be near terror targets.

Two of those folding "Men Working" signs, a sawhorse style barricade, coveralls and a pick also let you open manhole covers. If you choose properly you can find one that only gets opened once every 50 years. Making your deposit is easy, just put your stash in place and replace the cover.
Recovery is easy, you just lever the cover out of the way with your pick or bar, grab your stash and leave.
Remember that if you need to enter a confined space you should ventilate it and gas test it first.

Edit: If a city crew found your bucket they would either report it as found property or just divide it up among themselves.
So long as there are no guns in it there is nothing they would care about.