Hazards to the environment
You did never ever want this to happen! In particular it's the fault of the others! But the situation needs an quick apropriate action!
The canister is hopeless overfilled. Action has been needed much earlier!
The canister is placed next to a sink. The spilled waste is found 1 cm in front of the sink. In other words: It is just this single centimeter, which is separating you from a criminal charge by the envionmental agency - if they find out what has happened.
Solvent waste canisters have to be stored safely. Put them into a trough or a bucket so that spilled content cannot run into the sink.
But what to do with the overfilled cannister??