pump station occupancy category

huangyhg

pump station occupancy category
i have a potable water pump station that pumps water to a reservoir. water in the reservoir goes to the distribution system which is also used for fire protection. per ibc table 1604.5 is this occupancy category iii (water treatment for potable water) or occupancy category iv (water treatment facilities required to maintain water pressure for fire suppression)? of course i could use iv to be on the safe side but am looking to see if iii is justifiable.
thanks for your help.
-jason
i would think that iii could be justifiable if the pump station is not required to maintain fire protection supply and pressure for a "reasonable" length of time following an emergency.  
for instance, if the reservoir and downstream facilities can provide adequate supply and pressure for the length of time that the emergency back up system is required to run, the station would not be emergency-essential and could be designed cat iii.  
another thing to consider is the effect on the potable water if the pump stops running.
are there upstream issues which could introduce contaminants or untreated water into the pipeline/pump if the pump goes off-line, causing possible detrimental effects if not decontaminated after an emergency?
i'm in land development, so i do a lot with water supply/pressure codes but not much with ibc, so take it with a grain of salt.
we run into this all the time.  i would take a conservative approach and use category iv.  plus since most loads are defined in asce 7, table 1-1 in that document hints strongly that water utility structures be category iv.  
no one can argue that using iv is not the most conservative, but you could get an argument about using iii.  and when the design is complete, you don't want to lose that argument.
i feel that using occ cat iv is the only way that one can interpret the code as it is written.  i too have recently been in some extensive discussions about this with the project managers in my office.  i have been told also that a variance may be granted for a particular facility if the facility is more of a secondary facility for the fire suppression system, and the owner requests it.