Getting people to clear out their labs can be a nightmare. Over the years various sorts of science has gone on and there are usually no records of what has been kept in the lab in the past or gone up the fume cupboards. I eventually became sick of trying work out what the 200 odd vials that had been left in cupboards actually contained. So I created a checklist that describes what had been in the labs and what steps had been taken to remove it. I made it clear that it was the responsibility of the occupants of the lab (ie the scientists) to remove all of their crap.
Things that I looked at were:
• Fume hoods and microbiological safety cabinets- these needed to be emptied and decontaminated: they need to sign this off
• All reagents removed- sure that there were no mysterious bottles with no labels on them
• Check all of the cupboards are empty
• Check under benches- scientists had this habit of kicking anything that they dropped onto the floor under the benches rather that trying to get rid of it properly
• All equipment to be removed especially incubators, gas cylinders, radiation sources.
I insisted that either myself or someone from the H&S team actually go through the lab with the users to check and make sure all of this has been done
It is impossible to create a definitive checklist as each organisation labs are different. In some labs they handle extremely toxic substances in others the only thing they worry about is ethanol. You need to engage with the users to find out what sort of things that have been doing.
If there are things that they can’t do anything about you will need to come up with a usable plan generally based on a worst case scenario. For example: if you need to dismantle a fume cupboard that has not been used for years, don’t assume that it is clean: assume contamination and work around that. Make arrange to dispose of hazardous materials as soon as possible. Don’t be tempted to store then away in the hope that someone else will deal with them.

it's not the pools of mercury that are the problem: it's the tiny little blobs scattered into every corner that are a bugger to collect