I had a similar thing happen yesterday, I'd went into the shop that owned the dumpster & asked about it.
He gave me a 'OK' & his business card to flash if anyone asks me.



I then introduced myself & flashed the card to the people who own the closest house over looking the dumpster.
They were happy & said "They'd chase away anyone else seen there".

I ended up with part of a security system, two monitors & a still working photocopying machine (Gold gold gold!)
& some steel mains wiring boxes with brass connections in them.