Huxted Trenchless Sets World Record HDD in Virginia
The Newport News Shipping Channel in southeastern Virginia is one of the busiest shipping channels in the world. Crossing this channel with a new force main required a world-record Horizontal Directional Drill (HDD) supported by a team of experts to permit, design, and construct a challenging land-to-water HDD operation.
The Hampton Roads Sanitation District (HRSD) recognized the need for delivery expertise and utilized a collaborative delivery approach to deliver the Boat Harbor Treatment Plant Transmission Force Main project. This project is a component of HRSD’s Sustainable Water Initiative for Tomorrow (SWIFT) Program, which will improve local surface water quality while providing a sustainable source of groundwater.
The JRX design-build team, consisting of Huxted Trenchless, Garney Construction, Seaward Marine, Dewberry, Brierley & Associates, and Michael Baker, Inc., culminated in the world record 5,700 foot, 42-inch High Density Polyethylene Pipe (HDPE) installation under the James River and the Newport News Shipping Channel via HDD.
The team realized the tensile strength of the 42-inch HDPE pipe was a high-risk item that needed addressing. During design, we analyzed mitigation methods to reduce the pulling forces while installing the 5,700 feet of HDPE. A specialized HDPE pipe pusher was procured to apply compression to the HDPE pipe when pulling forces increased. The pipe pusher was equipped with special clamps that maintained the integrity of the HDPE pipe while assisting in the pulling process.
DrilRite developed a mud plan for Huxted that addressed the challenges of working in a soft soil formation, utilizing NSF 60-certified products. Measuring viscosity, mud weight, and cake wall, the drilling fluid achieved the properties needed at a 9.5 to 10.0 ppg mud weight required for a successful pullback.
Huxted engaged Brownline USA for steering assistance, so Huxted could perform an intersect drill within the soft formation. Brownline monitored pressures during the pilot hole to prevent drill fluid migration to the river bottom and mapped the installation of 900 feet of 66-inch conductor casing.
During the drilling and reaming operations, Garney fused 53-foot sections of the 42-inch DR-11 HDPE pipe into one continuous section near the shore of the James River. Starting on May 1st, 2024, tugs, barges, and marine escorts were utilized to tow the HDPE pipe string four miles to the working platform. Buoyancy control during pull back using river water was managed using a 6-inch tremie line, and load cells were used to measure fill rates. Under Huxted’s supervision, the product pipe, swivel and pull head were positioned and threaded through the pipe pusher using three crane barges to ensure the correct breakover was achieved.
The installation started fast, with the pipe moving without any delay, using only 100,000 pounds of pull force, which was supplied by Huxted’s 1.2-million-pound rig positioned on the North shore of the James River. As the pulling force climbed to 300,000 pounds, the pipe pusher was engaged to add compression to the pipe string, helping to prevent over-stretching. The pipe pusher started by adding 50,000 pounds of compression, and as pull forces increased, the compression was increased to 200,000 pounds. The final pull load recorded by Huxted was just over 525,000 pounds, 50,000 pounds under the recommended Safe Pull Load.
The installation took 22 hours of constant operation, and all post-tests were successful.
