I am currently working in a separate sewer treatment facility where a significant inflow of water is observed in wet weather in a small section of the network.
All connections have been checked and none are faulty.
CCTV inspection revealed no water entry points in the network, which is in good shape.
To our knowledge, no work performed after the network was commissioned would explain water infiltration between junction boxes and the network.
The only lead we have at the moment to explain this phenomenon is the presence of an agricultural drain.
Does anyone have any other ideas or experience with this kind of problem?
No sure of about your ag drain comment. Historically if this is a community type of system your problem is most likely roof or French drain issues from a residentially are or business. Have you performed a CS inspection on your system?