Project: Locating CSG Gatherings
Location: Toowoomba, Queensland
Contractor : Santos GLNG
Product: SnakePit Tracer Wire Test Station
Santos GLNG contracted Mitchell Water to lay polyethylene pipelines on one of the expansion stages of their Roma B gatherings project. The first stage of the project involved laying 75 kms of polyethylene low pressure gas and water pipeline between unconventional gas well heads and a central compressor station. The pipelines varied up to 800mm in diameter and were butt welded into continuous lengths. The pipelines were laid through agricultural grazing land, 300+ km northwest of Toowoomba in Queensland, Australia.
These gas and water gathering lines could be in operation for over 30 years, and as such must be able to be accurately located for maintenance. The owner also wanted to avoid accidental excavation, as rupturing active pipelines is dangerous and expensive to repair. As the gas and water pipelines laid were a plastic composition, standard pipe & cable location equipment could not detect them. Surface markers such as posts are often damaged with time by bushfires or livestock, making buried pipelines difficult to find.
Installing a Tapex tracer wire/ test station system has enabled the buried pipeline network to be easily located. The SnakePit (manufactured by Copperhead, USA) tracer wire test stations, along with a 2.5mm2 termite resistant copper tracer wire, were specified for the project by Santos. The whole system is designed to last the functional life of the pipeline. Tracer wire is buried in the bottom of the trench with the pipeline, being brought to the surface only at pipe junctions or 2km intervals. Here the tracer wire is connected to corrosion resistant brass terminals within the SnakePit test stations. The SnakePits enable a direct connection for a locator onto the tracer wire, without the need to excavate to hook onto the wire.
SnakePit tracer wire test station, is buried just below the cast iron lid (yellow for gas on this sample). The plastic shaft extends up to 600mm below the surface.
The Tapex termite resistant tracer wire runs beneath the buried pipeline up to several metres below, giving an accurate depth and location. The tracer wire has its copper core covered by a Nylon12 sheath (which is impervious to termites), then covered in an outer insulating PVC jacket.
The SnakePit test stations enabled quick and easy access for the locator operator to find the buried tracer wire network. The locator could hook their clamp onto the SnakePit terminals and pulse a signal down the full length of the tracer wire.
“I conducted the testing of all installed tracer wire systems on the project after completion. The accuracy of the SnakePit/Termite wire system is extraordinary. I can hook my transmitter on to the SnakePit terminal, run a low frequency current through the tracer wire and still locate the wire for up to 2kms from the terminal at over two metres depth” says Erik Sergeant, Mitchell Water.
“Compared to stainless steel systems we have used in the past, the SnakePit/ Termite wire locating system is very easy to use”.
Because the SnakePits are buried, with a cast iron lid sitting flat the ground, SnakePits are impervious to livestock and bushfire damage. Each SnakePit lid also has a magnet imbedded, so they can be located if the marker post is removed and become buried.
SnakePit lids can be colour coded and have the service name imprinted (eg. gas or water).