As the demand for a more resilient and reliable electrical grid increases, utility companies across the United States are turning to trenchless technology for infrastructure improvements.
The U.S. electrical grid consists of over seven million miles of transmission and distribution lines, the majority of which remain overhead.
“This setup makes the grid vulnerable to disruptions caused by weather events, falling trees, and wildfires,” says Mark Dorn, regional sales and product support specialist at TT Technologies during a presentation at the 2025 NASTT No-Dig Show in Denver. “As a result, utilities are investing significant resources into converting overhead distribution lines to underground systems.”
While the initial cost of undergrounding is high, the long-term benefits — such as enhanced reliability and reduced maintenance — make it a worthwhile investment.
“Trenchless technology plays a critical role in these conversions, allowing utilities to install underground electrical lines with minimal surface disruption,” Dorn says.
He detailed three projects where trenchless methods — horizontal directional drilling, pipe bursting, and winching — were instrumental in grid improvement efforts.
Compact HDD in Minnesota
One example of trenchless technology in action is a project undertaken by a major electrical utility in St. Paul, Minnesota. Many older residential areas in the city rely on overhead electrical distribution services, which are prone to outages due to high winds and tree interference. To enhance service reliability, the utility opted to convert overhead lines to underground using compact horizontal directional drills.
Given the constraints of single-lane alleys and backyards, larger drilling rigs were not a viable option. Instead, a compact directional drill — the TT Technologies 5X model — was used. Measuring less than 36 inches in width, this drill could easily access confined spaces without requiring the removal of fencing or other obstacles. With 12,000 pounds of pullback power, it was capable of executing 200- to 300-foot bores efficiently.
By implementing this trenchless solution, the utility eliminated the need for extensive tree trimming, reduced storm-related outages, and improved overall grid reliability.
“The HDD method allowed for both direct burial of conduit and pullback installation of electrical conductors, ensuring an efficient and effective upgrade to the city’s distribution network,” Dorn says.
Pipe bursting in Wisconsin
A second project showcased the effectiveness of pipe bursting in rehabilitating underground conduits at a manufacturing plant in Madison, Wisconsin. This project, conducted in collaboration with the Electrical Power Research Institute, aimed to replace two aging 6-inch steel conduits installed in 1987 with larger, more durable alternatives.
“Pipe bursting was chosen for this job due to its ability to upsize existing pipes with minimal excavation,” Dorn says.
The plant’s conduits, buried at depths of 3 to 6 feet, were replaced with 8-inch and 10-inch fusible PVC pipes. Given the lack of surface congestion, this method proved ideal for minimizing disruption while ensuring long-lasting infrastructure.
The operation required two pits — a launch and a pulling pit — along with additional observation pits to monitor the pipe-splitting process. The Grundoburst 800G machine, capable of exerting 86 tons of pullback force, was used to execute the pipe replacement.
“Despite some minor ground heave when upsizing from six to ten inches, the project was completed successfully, demonstrating the viability of static pipe bursting in electrical conduit replacement,” Dorn says.
Dual methods in South Carolina
The third project took place in Seneca, South Carolina, where Blackburn Contractors, in partnership with Duke Energy, tackled the challenge of extending electrical service to a new residential development adjacent to a lake.
“Given the geographical constraints, the only feasible way to install the necessary electrical conduits was through horizontal directional drilling beneath the lake,” Dorn says.
The project involved drilling a 2,300-foot bore at a depth of 150 feet beneath the water body to install 20-inch high-density polyethylene (HDPE) conduit. Within this conduit, nine smaller conduits were housed, each designated for carrying electrical conductors.
To facilitate conductor installation, a 3-ton Grundowinch was employed. This variable-speed, constant-tension winch allowed for precise control while pulling the conductors through the conduits. The process began with mule tape pre-installed in the conduits, which was then connected to the winch’s cable. With over 3,000 feet of cable available, the winch successfully pulled the conductors through each of the nine conduits, ensuring a secure and efficient installation.
The future of trenchless with the electrical grid
These three projects highlight the versatility and efficiency of trenchless methods in modernizing the electrical grid.
Whether through compact HDD in urban residential areas, pipe bursting for conduit replacement, or large-scale HDD combined with winching for complex installations, these techniques offer substantial benefits in terms of cost savings, minimal surface disruption, and long-term reliability.
“As utilities continue to invest in undergrounding initiatives, trenchless technology will play an increasingly vital role in ensuring a resilient and dependable electrical infrastructure for years to come,” Dorn says.
