Localization of leaks in buried pipes through microwave reflectometry: A practical test case

In this paper, a time domain reflectometry (TOR)based system for the non-invasive localization of leaks in underground pipes is described and experimentally validated. The proposed system simply relies on TOR measurements performed on a two-wire cable (biwire) that is rolled out on the underground pipe at the time of installation of the pipe (but made accessible from the road surface through an inspection well); the biwire on the pipe acts as a permanent, distributed sensing element and can be connected to the TOR instrument whenever it is necessary to perform a check. Two of the major advantages of the proposed system are that it can be employed with pipes made of any material and that it strongly reduces the inspection time typically required by traditional leak detection methods. To validate the system and to assess its performance, a new pipe was installed and a leak condition was intentionally provoked at a reference position. The TOR system was then used to evaluate the position of the leak as if had been unknown. The results of this experimental test are reported and thoroughly discussed.