Utilizing Technology: Protection For Underground Utility Lines

Construction & Contractors Blog

Civil engineers are responsible for protecting underground utility lines from damage during an excavation exercise. Traditional excavation methods (e.g. hand-digging and using backhoe excavators) often require a lower capital input, but they expose utility lines to the ever-present risk of damage as a result of sudden impact from excavation equipment.

This article discusses two ways in which the threat of damage to utility lines can be mitigated. Student engineers should find this information useful.

GPR Scanning

The best way to protect underground utility lines from the threat of damage is to identify the exact depth of utility lines running below the ground. However, it is often difficult for an engineer to do this without digging up the road surface.

GPR (ground penetrating radar) machines can be used to accurately estimate the depth of underground utility lines. These machines are fitted with transmitters that send electromagnetic waves through the road surface. As the waves penetrate into the ground, they are refracted or reflected back to the surface by obstacles (e.g. pipe conduits) that they may encounter on their way down.

The GPR scanner is a computer-controlled machine and it has the ability to detect and record and analyze the varying characteristics of the refracted/reflected electromagnetic waves. This analysis is used to estimate the depth of sewer lines that run below the road surface. Knowing the estimated depth of underground utilities allows a civil engineer to dig up the road surface while minimizing the likelihood that they will interfere with these utilities.

Vacuum Excavation

Estimating the depth of underground utilities might not be sufficient to protect underground utilities from the risk of damage. This is especially true if traditional methods will still be used during the excavation exercise.

Vacuum excavation is a less-destructive method of digging up the ground. A suction (vacuum) excavator uses compressed air to "suck up" soil and other materials present below the road surface. Suction excavators that use compressed air have several fans that generate the required air flow. The generated air flow is channeled through the intake nozzle of the excavator. The nozzle is introduced below the road surface, and the compressed air sucks up soil and debris from beneath the surface. The "sucked up" soil is delivered to a disposal tank mounted on a truck.

With the estimated depth of underground utilities in hand, engineers are able to prevent damage on utility lines by ensuring that the intake nozzle of a suction excavator doesn't go too deep into the ground.

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23 June 2016