Properly exposing underground utility lines is crucial to keep job sites efficient and crews safe. This includes using a safe potholing technique, like hydro excavation, to help reduce damage to sensitive infrastructure.
Accidentally hitting an underground water, gas, or electrical line during a construction project is costly and potentially dangerous. This is why having visual verification of where lines are buried is essential.
While it’s common knowledge to “Call Before You Dig” and have underground lines marked before beginning construction, visual verification is the best way to protect your crew from costly damage. While other locating methods like electromagnet and ground penetrating radar are effective, they’re not as precise as potholing, which involves drilling test holes to expose buried utilities so you can see them.
This non-destructive process utilizes pressurized water (hydro) or air (air vacuum excavation) to soften and displace soil from the test hole, while high-suction vacuum excavates uncovered features. This technique ensures that gas, electrical, and water lines remain intact while minimizing site disruption.
It’s also much faster and more cost-effective than traditional hand digging and backhoeing, making it a preferred contractor method for utility mapping. Accurate mapping prevents strikes on critical underground infrastructure regardless of your choice and minimizes the risk of personal injury, property damage, service interruptions, and costly repairs.
Pressurized Water & Air Excavation
Using a pressurized jet of air or water to dig test holes for existing underground utilities is known as potholing. Unlike older methods, this process is fast and accurate. It helps to keep construction crews safe and prevents unnecessary downtime. It also ensures that no lines are accidentally damaged by complex equipment.
Moreover, it is more efficient than digging with backhoes for various reasons. A backhoe can easily damage a utility line while trying to expose it. It can also contaminate the digging area with drilling mud.
Thankfully, implementing a safe utility mapping strategy by Daylighting Festus MO before starting construction or excavation work has become more accessible, thanks to modern tools and methods such as hydro and vacuum excavating techniques. Using these technologies eliminates the risk of damaging vital infrastructure, keeps projects on schedule, and avoids costly noncompliance fines. These techniques are also environmentally friendly and more cost effective than relying on charts or a backhoe to find underground lines.
Ground Penetrating Radar
Ground penetrating radar (GPR) is a non-intrusive geophysical method that sends electromagnetic pulses to measure contrasts and distortions in the ground. The signals pass through the subsurface, reflected from asphalt, cables, metals, concrete, or masonry. The system then translates the reflected signals into a visual file that can be reviewed on a screen.
GPR is ideal for many applications, including utility mapping and finding buried archaeological artifacts. However, the soil’s conductive properties can limit the results’ depth and resolution.
GPR can also be difficult to use in clayey or silty soils, freshwater or saltwater (ground or lake/river), paved areas, and freshly salted roads. For these reasons, it’s essential to test the ground’s electrical conductivity before determining if this tool is appropriate for a particular investigation. GPR is an excellent alternative to traditional backhoe digging. This is because it allows for a quicker and less dangerous utility location.
Although laser scanning is a relatively new technology, it’s becoming increasingly common in construction projects. It works with other technologies to improve safety, quality, and accuracy. In addition to eliminating the need for backhoes and exploratory digging, it provides accurate as-built documentation and helps reduce rework and project costs.
Laser scanning is the controlled deflection of laser beams to capture and record a 3D representation of a surface. It creates point cloud models, each containing a registered intensity value (or color value) based on the strength of the reflected signal. These bright-colored visuals help contractors and engineers pinpoint the location of buried utilities and other existing underground infrastructure.
The point clouds can then be incorporated into a BIM model, helping to speed up the design process. For example, Gilbane has used its completed laser scans to create Revit models on some of its projects, resulting in cost savings and significant improvements in project efficiency.