Locating underground gas pipes

Underground gas pipes can be easy to find. If you have a leak, you will need to find your buried gas pipes fast. If you want to undertake a renovation, landscaping or excavations, you will need to know where the underground gas pipes are so that you do not damage them while excavating. Damaged gas pipes are dangerous and can cost thousands to repair.

Dial Before You Dig plans only show the gas utility’s main pipes outside of the property and in easements running through properties. They do not show the location of privately owned underground gas pipes or branch lines running to a private gas meter. If you are undertaking mechanical or vigorous excavations in the vicinity of an underground gas pipe, once you have settled on the location of the gas pipe you must dig it up by hand or hydrovac to expose it and prove its actual location. Do not attempt to prove its location with mechanical excavators apart from Hydrovac excavations. If we plan to mechanically excavate within 1.5 meters of a gas pipe, we will expose it by shovel or hydrovac first.

Not all underground gas pipes will have marker tape above them, in the same trench, to alert those undertaking excavations of their presence. If you come across marker tape while mechanically excavating stop digging immediately. Marker tape will indicate that you are likely directly above a vital underground service. You must either move your excavation or expose the underground service by shovel or hydrovac method. Yellow marker tape will indicate that you are directly above a buried gas pipe.

Underground metal gas pipes are the easiest to find. Copper gas pipes and galvanised steel gas pipes are conductive. A metal detector in the hands of an experienced operator may do the job. We induce an electronic signal into the metal pipes and then use a locating device with an inbuilt receiver to find that signal. This method is very accurate and allows us to determine the depth of the underground gas pipe as well as the location.

Underground plastic gas pipes are usually owned by the gas utility or network operator. Normally, they are installed with a metal tracer wire running parallel to the gas pipe. The tracer wire can be found using the same methods used for finding underground metal pipes. However, we would not recommend the spike method, used for buried water pipes as you could easily pierce the wall of the plastic gas pipe.

Underground plastic gas pipes without a metal tracer wire are extremely difficult to find. The ability to find these pipes takes years or experience, training and intuition. Once the likely location of the gas pipe has been determined, we would recommend the use of a Hydrovac excavation system to remove the soil in a narrow 500mm deep trench, crossing the gas pipe at 90 degrees to the expected location of the buried gas pipe. We would lengthen or deepen the trench until the gas pipe is located. We would not recommend the spike method, used for finding a water pipe trench as you could easily pierce the wall of the plastic gas pipe.