This article is all about avoiding utility strikes while locating underground utilities.
In it, we’ll explain how to locate underground utilities by looking for visual clues using cable locators and why potholing is a critical process in avoiding a utility strike.
Walking around your worksite is an important part in finding visual clues of what utility services are present, looking for signs of services and utilities above ground indicates things that may lie below ground down before you dig plans give you an idea of the services you should be able to identify even if you can't see them. Your dial before you dig plans need to be available on site.
Walk around your site and look for clues of electricity, communications,
gas, streetlights, water and waste. Look for physical clues like access chambers, pits, valves, marker posts and warning signs, curb markings, damaged footpaths, driveways or depressions which may indicate the presence of a trench.
If you intend to dig deeper than 30 centimeters within three meters of any electrical infrastructure, you are might be required to request a network access permit. All these services are connected to buildings or other infrastructure and are not always in a straight line.
One way to take the worry out of locating buried underground assets is to use the services of an accredited locating company.
There are two main techniques for utility location, electromagnetic induction and ground penetrating radar. Electromagnetic induction uses a transmitter to energize the utility with a current setting up an electromagnetic field. This is then detected using a receiver. ground penetrating radar uses radar pulses emitted into the ground. When these pulses strike a charge in the subsurface like a pipe or cable. They are reflected back to the radar unit and the results are displayed on a screen for the operator to interpret.
If you're using your own locating equipment, ensure the operators are trained in how to use it and aware of its limitations. The equipment must be calibrated and capable of detecting all types of cables and pipes. Some locating equipment may not detect an electric cable unless there is current flowing through it and may not be able to detect nonmetallic pipes or cables.
It is common for some assets to be laid with detectable foil back marker tape or non-detectable market tape and a tracer wire making it easier to locate. But this is not always the case. Some assets like fiber optic cable cannot be located without specialized equipment.
Once the asset location has been found digger pilot hole where you intend to excavate. This is known as potholing and is used before excavation to identify how the lines run underground. Every effort should be made to excavate alongside an asset rather than directly above it. Using appropriate personal protective equipment and insulated hand tools is a safe method for potholing.
How you use your hand tools is important. There are a common source of incidents and can damage the asset if used incorrectly. spades and shovels should have curved edges and should not be thrown or spiked into the ground but eased in with gentle foot pressure. Always dig across the asset not along its length.
Another safe method of potholing is vacuum excavation, which is a fast and usually non destructive way to locate an exposed underground utilities services. It must be noted that water jetting at some high pressures can damage cables and pipe coatings. Whichever method is chosen, you need to apply it with care. Remember, the more risky the job the more frequent the potholing. If you're excavating near high voltage electrical cable or high pressure gas lines, always contact the asset owner for a permit and onsite assistance if required.
So in summary, always have dial-before-you-dig plans available on site. Look for visual clues of services. Use cable locators to identify hidden assets, clearly mark all services on the ground. When working near electricity assets. Do not proceed until a permit has been issued.
Always potholed prior to excavating using insulated tools carefully and where appropriate personal protective equipment. Remember, never assume services marked on the ground or correct run in a straight line or have been installed at a consistent depth. always verify location by using careful potholing and frequent intervals along the services. Now that you know more about locating underground utilities, the next episode we'll explain how to carry out excavation work.