A acoustic underground water leak detector could find the leaks quickly. The equipment should be similar as below:
The UG fire network is 1.5 km - is quite more to look in. You could use air release valve in respective desired locations to release the air in case. Water hammering would come in the said network to have; usages of jockey pump (working) continuously to consider in the plant.
The same shall be in line with the leakage happening in the pipe (UG) fittings and other stress parameters.
Are you using GRE pipes!, if so, the pressure setting of jockey pump(s) and other allied parameters to be checked to proceed.
9 times out of 10 if a jockey pump is cycling, you have a check valve failing to seat and water is flowing back through the check valve into the tank or water source. I've seen quite a few check valves fail in service and it has the exact same consequence as the ones you are describing.
Isolate each check valve one at a time and see if that stops the pressure cycling.
Yes, isolate or replace pump room check valves then see about UG.
What I think is that you should do water quality tests with indicators of dissolved oxygen maybe ph or salinity, in short whatever it may give you an idea of the sector that circulates the water and the one that does not. It is important to start mapping the quality from the hydrants closest to the pump room so that the rest of the network remains in unchanged conditions during the course of the test. luck!
Sir first isolate the pump room and check the pressure drop in pump house and fire water line.
[While this is not a troubleshooting Forum, it's a fun problem]
'This happened to me'
Treat is like an Electrical Circuit - go half way across - is there Pressure? And so on.
The first Riser out of the Loop must be Shut OFF and Shut OFF another Riser half way across the circuit.
In my scenario below, the Jockey Pump kicks ON so the leak is on the left run.
Open the first Riser out of the loop and pick a Riser half way around the circuit to Shut OFF.
In my scenario, the Jockey Pump doesn't kick ON, so the leak is in the top circuit.
Open the top left Riser and shut OFF a Riser half across the top run.
In this case, the Jockey Pump kicks ON.
Open the top right Riser and Shut OFF a Riser further in the circuit from the previously closed top left Riser.
In this case, it doesn't kick ON. Shut OFF a Riser closing in.
In this scenario, the Jockey Pump kicks ON so the leak is the other way.
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