Drilling for a 230kV underground transmission line in Haymarket, VA.

The town of Haymarket in Prince William County, Virginia, will become home to a new data center. In order to power this complex, a new 5.3 miles long 230kV transmission line will be constructed. Part of this transmission line will be underground, for which Brownline surveyed 4 drills.

The underground portion of this line starts at Heathcote Substation, from where it will cross the interstate highway I-66. After following the interstate westwards, it crosses the I-66 again to end at the Haymarket Substation. This second crossing of the I-66 was surveyed by Brownline with the Drillguide Gyro Steering Tool in combination with the GPS Track for additional verification. This trajectory consisted of 4 drills in total, each approximately 2500ft in length. These 4 pilot holes will each contain a 48” HDPE product pipe, through which the high voltage lines will be pulled.

Haymarket itself is a historical town in an area that has a long history as well. In the past it was used as hunting ground by the western Iroquois nations. The hunting paths created in this era led to the current nickname for Haymarket; The Crossroads. The combination of several roads, existing historical infrastructure and vulnerable nature along the drill trajectory called for the necessity of constantly monitoring the pressure to avoid inadvertent release of drilling fluids. Besides this, the client also set very strict demands for the target depth, which had to be met within 1’ of accuracy.

Brownline’s expertise combined with the Drillguide GST and GPS Track ensured that all demands were met and that the project was successfully executed.


This project received an honorable mention for Trenchless Technology's Project of the Year 2022 award, in the category "New Installation".


Back to overview