Recently Dominion Energy needed a project completed in Myrtle Beach, South Carolina. South East Connections was hired as the general contractor to complete Phase 1, which included the installation of a little more than three miles of new 8-in. steel gas line.
West Concord, Minnesota-based Ellingson Trenchless (dba ECI Contracting) was retained to complete the horizontal directional drilling (HDD) work on the project which consisted of three separate HDD bores. The largest bore — a 6,285-ft bore — required extra planning by the ECI team in order to meet project schedule requirements and an elevated risk of inadvertent returns. Additionally, the bore was positioned along a busy highway and traffic created challenges.
Because of these requirements, the team determined that an intersect crossing would be the best path forward to complete the project on time and without environmental issues. An intersect is an HDD process in which two drill rigs are set up on each end of the bore and pilot toward each other and meet at a predetermined point on the profile. The rigs then work in tandem to complete the reaming process of the bore. Finally, one machine is moved out the way and the other bore performs the pullback of the product pipe.
ECI project manager Neal Roberts believes that the success of the project was due to the unique process and because Dominion Energy, South East Connections and ECI all engaged as a team to come up with the best plan.
“Great planning and communication throughout the project from the gas company to the general contractor and, to us as a subcontractor, was excellent. All three were involved in all meetings before and during the project. Made things a lot easier working as one team,” Roberts says.
Two Prime Drilling 250 drill rigs with more than 600,000 lbs of pullback force were used as well gyro steering technology to ensure the most accurate alignment and intersect were met. Gyro steering services were provided by Inrock. Additionally, ECI Contracting’s own team of geologists and HDD experts reviewed soil conditions and determined the best drilling mud recipe to prevent inadvertent returns and have a clean, slick hole prior to pipe pull back.
Ellingson Companies onsite general superintendent Derek Vogel and his team completed the entire project under 30 days. “A 6,285-ft HDD is no easy task and is typically tougher to complete in softer formations as you run into higher risk of having inadvertent returns and can have steering issues staying on the bore path as designed. Derek [Vogel] and the crews over came all of these challenges and did a fantastic job,” says Roberts.