You need CALM network training, which is a free online course to certificate yourself that hydrants are used correctly.
Taken once per year it shows that you know what you are doing with them, opening them, closing, sanitising, not allowing surges on the system, common sense.
You then need to go to each supplier and hire hydrant risers, per week basis plus any water usage in m3.
Someone like Aquam Corps are a one stop shop for several networks and keep info on system - you still need to do the paperwork on every hire.
You are also only meant to use wash outs (WO's) on the plate and not fire hydrants (FH's).