Common Underground Utility Location Methods

The general campaign for locating utilities is to dial before you dig. No matter what area you live in, if you dial 811, you will be connected to request that utility companies come and mark the location of underground lines. However, you may need to contact a private locator company if you need additional information in some cases. Not only does an accurate utility locator prevent serious injuries, but it also can prevent service disruptions. Learn more about the standard methods used to locate underground utilities.


Electrical Methods

Though some interference from metal structures nearby can interrupt the locating process with electrical methods, it is a method that is useful for finding all utility materials. This approach works by inserting two pairs of electrodes into the ground and measuring the resistivity from the horizontal profile between them along a survey line.

Direct Methods

Direct methods typically include excavation and exposure of the buried utilities. This method finds the utilities but can be dangerous because digging too close could contact the lines.

Electromagnetic Methods

Two types of electromagnetic methods are used to locate underground utilities: frequency-domain electromagnetics and time-domain electromagnetics. FDEMs is a utility locator that uses an electromagnetic current and determines the phase and magnitude by measuring the soil’s electrical conductivity. Time-domain electromagnetics uses a short-duration electrical pulse into the ground. The amplitude of the electromagnetic flow is calculated by using a receiver coil to determine the decay of its magnetic field.

Potential-Based Methods

Highly effective on metallic utility location, potential-based location methods include location by both magnetic and gravity potential. Buried metallic and ferrous objects are found when the potential contrasts with magnetite.

Ground Penetrating Radars

Possibly what people imagine an underground utility locator to look like, ground-penetrating radars are microwave pulses that come from an antenna and are transmitted to the ground. The reflections from subsurface objects or utilities are projected on a receiver that builds on-screen resolution of subsurface strata. This method is useful for all utility locations and can be operated by hand or from vehicles for larger survey fields.

Pipe Tagging Methods

Radiofrequency identification tags are markers used to provide site-specific information for buried infrastructure. Much like a tag scanned in the grocery or at a clothing store, the pipes are tagged with markers that give a digital response to a utility-specific radiofrequency projected into the ground.

Multisensory Technology Methods

Multisensory approaches to finding underground utilities combine methods to ensure that the location data is correct. Some findings may be more complex to read and can easily provide inaccurate results, leading to disastrous consequences. When situations arise that have familiar complications, multisensory approaches are applied.

Instead of digging to explore utility potential, which may end up being the most functional approach, the first set of solutions typically includes a combination of ground-penetrating radar and time-domain electromagnetic methods. The size of the survey site might also change the variety of techniques used; those easily installed on trucks over handheld or rolling are preferred for larger areas.

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