Test Holes: Confirming Your Utilities (Or Not?)

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Evan Mowbray

Test Holes: Confirming Your Utilities (Or Not?)

Locating utilities is an important part of any underground project. Trinity services clients by utilizing ground penetrating radar scanners and EM locators; these tools help identify safe digging areas by determining the horizontal location of utilities. Vacuum excavation can act as a supplemental tool to utility locating. Sometimes there are unexpected, abandoned, and unknown utilities. Not everything has a clear connection point to an existing surface feature, such as an electrical line connecting a light post or a gas line connecting to a gas station. As stated in a previous blog post, subsurface utility information ranges from Quality Level D to Quality Level A data, with A being the most accurate and D being the least accurate.

An image of a Trinity Subsurface vacuum excavation truck potholing for underground utilities in a parking lot in Lancaster, Pennsylvania.

At some point, information may become lost due to time and rely solely on word of mouth or accounts of people who were around for previous projects of construction’s past, reducing the quality of information down to Level D. Sometimes, test holes are the best option to mitigate this. What if you’re looking for the exact vertical location of a utility? Some utilities may not be too deep under the surface. What if you need to determine the properties of the utilities and need to expose them to reveal their conditions? What if you have no idea what you may find underground due to unforeseen factors? Making sure you’re safe to dig in specific spots will help with any planning and readjustments for your next project. That’s where vacuum excavation often comes in.

Vacuum excavation can be used to create holes in the ground, often through a technique known as potholing. Our team at Trinity utilizes vacuum excavation in a number of projects, from trenching to potholing with both air and hydro excavation techniques. Test holes are smaller holes made in the ground, using vacuum excavation in multiple spots to understand subsurface utility information and raise the quality level of that information significantly. There’s often more than one test hole involved in a project, sometimes involving dozens of test holes to determine the exact locations, directions of utility lines, and the physical characteristics of your utilities.

Left: An image of a vacuum excavation crew using a vacuum excavation truck to locate underground utilities. Right: An image of exposed utilities in a pothole created using a vacuum excavation truck.

 Test holes can be stretched across an entire project, or focused on a single area where utility congestion may become too much.There are two things that can happen with a test hole: You confirm the location of an underground utility, or you don’t find anything. In a recent job, we were able to locate water, gas, and fiber optic communication utilities within a stretch of test hole locations within a parking lot, feeding into a nearby building. Sometimes you can find underground structures not detectable using ground penetrating radar or long forgotten with time. Test holes may lead to further investigations. Not finding utilities where they’re expected may require more test holes. but are incredibly helpful for uncovering important information about what’s underneath your next project. If you need vacuum excavation services, whether you’re trenching, boring, or making test holes, our team at Trinity Subsurface can help! Check out more of our website to find out about our services.

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