From the magazine, HDD, Microtunnelling, Pipe jacking, Tunnelling

What lies beneath

Any excavation job, including minimal excavation works such as auger boring or directional drilling, has the potential to damage underground assets.

Although auger boring is normally performed much lower than the 2 m depth where the majority of services infrastructure is installed, it is still important to clear the area for underground assets that could be buried deeper. Crucial services may be buried up to 8 m deep, which is well within the depth of auger boring works. The services that auger borers are most likely to come across at deeper depths are sewers, stormwater systems and major pressurised water trunk feeds.

It is important for any operator performing excavation works to utilise Dial Before You Dig (DBYD) to obtain all the relevant underground asset plans of major asset owners that may be buried within a scope of works. The DBYD plans must be current and on the worksite before proceeding with any kind of excavation. Once plans have been obtained, the operator may scan the area using pipe and cable locator technologies including EMF locators, ground penetrating radar (GPR), traceable rods and sonde transmitters. Operators may also need locators that locate the passive markers that are sometimes buried with services. Each of these technologies will assist the operator in reducing the risk of striking pipes or cables.

It is important to recognise the different technologies work together and complement one another; just using one type of instrument may not clear all the area of underground services. For example, an EMF pipe and cable locator may pick up power cables but may not pick up a stormwater or sewer pipe buried deeper down, so an experienced operator will utilise a high powered sonde in addition to equipment to access the network through an inspection opening. The operator may also have a GPR unit that will also locate the same service if the soil conditions are favourable.

If the company or operator doesn’t want to invest in the equipment and training, then the quickest avenue might be to use an experienced locator contractor. Contractors can be found through the National Utility Locating Contractors Association (NULCA). Most NULCA members are fully accredited, have lengthy experience in the industry and will have the correct instruments and training to clear the project area for services.

If operators choose to invest in the equipment to perform their own locations, there are many quality locating instruments on the market including Rycom, Radiodetection, UtiliTrac, IDS and Mala – these are just a few of the brands available. If an operator chooses this option, they should check to see if the company providing the equipment can offer professional training for it. Alternatively, the operator could choose to complete a two-day training course provided by NULCA training contractor JB Hunter. This course is the only fully accredited course available, and teaches the operator the correct techniques for locating services.

Remember, the onus is on the operator to clear the area for services, and operators can be liable for millions if they damage a utility service. Operators must ensure they have a current DBYD plans and use all the technologies available to them to locate these services and most of all dig safely.

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