One could just speculate around the history and contents of these drums and how they finally ended up here in this forest...

How about it all started with a phone conversation some 30 years ago or so:

Caller: Is this Mr Scrapper's Green Chemical Disposal Service ?
Mr Scrapper: Yeah, *cough*, who's calling ?

C: I have a couple of barrels filled with some nasty stuff. I'm keen it's disposed of in a responsible manner.
S: Sure, not a problem, we do this for living so trust me *snort*. It ain't gonna be cheap though, I can tell. Waste like this has to be handled properly *snarl*

C: Deal - I just want these things out of my sight
S: Alright, *cough* I hear you *ruckle* I'll come by and take care of it