To add to what others have already said consider the benefit of high ceilings, whether there is an unhindered view of the length and breadth of the building, location / number of final exits, places of temporary and absolute safety around the building and the site as a whole. Are then any lone plant operators working at height in isolated control cabins within the building?
I'd also consider other factors such as: how well the machinery is maintained, and the standard of house keeping - are waste groups sorted and segregated - is it a well organised operation or simply organised chaos? Is waste left to fester for long periods of time? If so does it get regularly turned over ?
In my experience migrant workers are often employed at waste sites - so consider the staff - is english their first language? - do they understand what to do in an emergency, would they understand the shout of fire.
Are gas powered fork lifts (or other vehicles) in operation within the building, are there battery vehicles in use? If so where are they charged? Some "trommel" machines have their own internal fire suppression systems? Are there any at this particular site?
All those considerations would help me to decide if I needed a fire alarm system, and whether it needs to be automatic or manual. Again height of the ceilings, how dusty the place gets, the realistic benefit of utilising automatic visual warning and audible warnings should be weighed up as well as the need to shut down equipment in the event of fire.
If you are going to be tasked with creating the emergency plan for the site consider that particularly at waste sites a fire could take days to extinguish especially every last hotspot, depending on what is being processed.
I would certainly contact the local fire service and invite them down to conduct a site survey.