Abandoned Utilities: Leaving Infrastructure Underground
There are tons of active utility lines being used throughout the world, providing electrical, communications, gas, water and wastewater services. They’re maintained, inspected, and may appear on as-built surveys. However, there are also a lot of utilities that are no longer in use, either due to their age or construction over time. Sometimes these lines are removed prior to new construction. Sometimes they’re left to sit in the ground, slowly being forgotten about for future plans. It’s like you’re burying the line twice when you abandon any utility.
Utility abandonment doesn’t always happen due to pure negligence to remove existing service lines. Sometimes utilities are installed through horizontal boring, which may go under other existing infrastructure. Removing these deeply drilled lines might be an expensive or unfeasible undertaking and, as a result, they’re often abandoned in place. This is likely why most states haven’t regulated abandoned utilities as much as active utilities, although there are states that have implemented laws stating that the utility owner still retains ownership after abandonment. Access points may be capped off and demolished, making them difficult to see from the surface. These utility lines may stop appearing on new plans, and old plans where they were marked may be phased out entirely. This makes a utility an abandoned utility. What are the problems with abandoning a utility line? How can we take care of abandoned utilities before they become bigger problems?
Abandoning a utility creates subsurface clutter beyond active buried utilities. Utilities are often buried close to or intersecting existing lines. This comes with careful planning and investigations into where utilities are known to exist and knowing the safe amount of clearance to install new utilities. One water line is easier to work around compared to two, and because these lines can fall off of active utility plans, abandoned utilities can create confusion on what may or may not be active. The Common Ground Alliance treats located or exposed abandoned lines as active lines. Another issue is that certain utilities can create soil contamination if not maintained. Buried lead lines (see last week’s blog post for information on lead lines) can leach traces of lead into soil that can be harmful to humans and the environment, making abandoned lead lines even more of an issue.
Dealing with abandoned lines involves investigation into existing utilities. This may involve examining existing plans for both new and old projects to have a starting point for locating anything that’s been abandoned. This can start with using ground penetrating radar, electromagnetic locators and split boxes to determine the existence of potential abandoned lines. If the access points to these lines are still accessible, it can make finding these lines much easier. Another way to determine the extent of an abandoned utility is by using vacuum excavation to perform test hole investigations. By physically digging down to the utility using air or water, you can see the exact depth of the line and the direction of the line without damaging underground infrastructure. In the image above, our team at Trinity was able to find an abandoned utility structure at a gas station by digging a test hole under the asphalt.
If you need to investigate the active and abandoned utilities at your next project site, our team at Trinity Subsurface can help. For more information on all of the services we offer, visit our website to find out how we can provide you with the information you need to avoid utility strikes.
