29 Mar Horizontal Directional Drilling Ties Progress to Preservation in Hudson River Valley
More than 400 years have passed since explorer Henry Hudson sailed up the river that would eventually bear his name, searching in vain for a passage to China on behalf of the Dutch East India Company.
Upstate New York’s Hudson River Valley of today is far from the savage wilderness Hudson found in 1609, but enough of its natural, picture-postcard beauty remains to steal one’s breath away at first view. And thanks to environmental conservation efforts started in the early 1960s, much progress has been made in improving water quality and otherwise preserving the area’s abundant natural resources.
So, as with all projects for Southeast Directional Drilling, minimizing the environmental effects was of paramount concern. The project, which involves a natural gas pipeline crossing underneath the Hudson in an existing right-of-way near the U.S. Military Academy at West Point, will bring affordable, domestic natural gas from the Appalachian Basin northward to meet increasing demand in the Northeast.
Fortunately, progress in drilling technology, particularly in the area of horizontal directional drilling (HDD), enables oil and gas companies to increasingly preserve the environments in which it operates, said Josh Ugrich, Vice President of Estimating and Project Management for Southeast Directional Drilling (SEDD), a PLH Group Company, the contractor responsible for the Hudson River crossing project.
“With HDD, we can drill deep beneath the riverbed from two sites on opposite shores, leaving the river between undisturbed,” Ugrich said.
HDD — a Business That’s Cleaner for the Environment
In October, SEDD mobilized 10 truckloads of equipment from a recently completed HDD project involving wetland, river and interstate-highway crossings in Illinois to upstate New York and began site preparation on the two areas on the eastern and western banks of the Hudson where drilling would initiate. SEDD stabilized the area with matting and planking, which also helps to prevent erosion.
HDD technology makes crossing rivers, highways and other areas cost efficient and practical although the process by its very nature is a muddy business. The pit in which the drill head enters the earth and into which the piping is fed resembles nothing so much as a large hog wallow.
Hoses bring up ground-up cutting debris from the drill hole and feed it into an elaborate piece of equipment known as a mud system. The mud system screens and shakes that debris to filter out cutting bits that include small stones, sand and silt, discharging them into cutting bins. Waste disposal vacuum trucks haul the discharged cutting bits away to EPA-approved disposal sites.
The mud system mixes what remains with water and sodium bentonite to create — as its name suggests — mud. More specifically, Ugrich said, an oozing sort of mud with the consistency of thick, melted chocolate. This recycled mud is actually pumped back down the drill hole to help carry more drill cuttings back up to the surface.
SEDD employees measure the weight, viscosity and sand content of the mud at regular intervals and adjust it as necessary, Ugrich said, depending on the formations the drill is encountering at any given time.
“If you’re drilling through rock, you’ll want a thicker viscosity mud to help carry the heavier cuttings up out of the hole, as compared to the lighter viscosity mud you’d run when you’re drilling in clay.”
Meeting in the Middle
While all of this activity takes place in mirrored sites on each side of the Hudson, which is 0.7 miles across at this spot, the river itself flows peacefully between them, like nothing’s going on underneath it.
It will continue that way, even as the two drill heads progress to a depth of 140 feet below the river bed and make their way to one another across 4,893 horizontal feet of distance. How the two drill heads meet in the middle instead of passing like proverbial ships in the night is the technology that makes HDD river crossings possible. GPS-guided, gyroscopic steering tools in the drill heads allow a spatial engineer back at each drill site to take readings, make calculations and provide precise direction to the drill head operator at the control panel next to him.
When the two pairs of engineers and operators guide their respective drill heads under the river to meet in the middle and join the two drill pipes, the job is still far from complete. That’s because the pilot hole must be enlarged gradually from its initial 12-inch diameter to 24, 36, 48 and finally 56 inches to accommodate the 42-inch diameter pipe that will be pulled through it and left in place permanently for the pipeline, which is scheduled to be operational in November 2016. SEDD will perform the enlargement using increasingly larger reamers. The drill rig on the western shore will pull and rotate the reamer while its eastern-shore counterpart assists with rotation.
Back to Nature
Once the Hudson River crossing is complete, SEDD will pack up its 10 truckloads of equipment and move them on to the next jobsite. And while the river will have remained undisturbed during the HDD work, the two drill sites on either side will then be restored.
“They’ll restore the areas as close as possible to their existing condition prior to our being here,” Ugrich said. “That includes backfilling the area that was dug out with the original rock and topsoil that’s been kept on the drill sites. This will return the hillsides to their original shape and appearance, and then they’ll revegetate to prevent erosion. Within another year, as nature takes its course, no one will be able to tell we were ever here.”
About Southeast Directional Drilling
Southeast Directional Drilling (SEDD), a PLH Group Company, delivers combined team field experience of more than 200 years in pipelining and directional drilling. The company has experience in all types of soils, including solid rock and fractured formations with the capability of drilling in lengths in excess of 6,400 ft, ranging from 2 inches to 56 inches in diameter. The company’s latest record was set in Trinidad by successfully completing three 56-inch horizontal directional drilling (HDD) crossings, each over 2,200 feet long. This set a new world record for the largest diameter performed by the HDD method. For more information, visit southeastdrilling.com.