Yoop:
"then Fire pump kicks on to maintain pressure."
By definition, that sounds like a pressure maintenance (Jockey) pump, and not a fire pump.
IMHO, as you say this is a Twp. pump, they should be giving you the specs for what they want/require. The 'spec' & drawings by a PE/EE/Arch are required to get plan review approvals (based on NEC) and permits issued.
This also relieves you of any liability for the 'design', unless you have DB coverages and do the design.
