A 10-mile pipeline that will connect the north and south sides of Hampton Roads Harbor — made possible through onshore and marine horizontal directional drilling — will allow Virginia Natural Gas (VNG) to expand capabilities to serve a growing customer base and will also open new doors for HDD projects, industry experts say.
The project’s onsite work began in May 2008 and is scheduled for completion in November 2009, with the final land-to-water shore approach completed and tie-ins of the 24-in. steel product pipe now under way. At the heart of the project were seven HDD crossings completed by Mears Group Inc. working closely with the prime contractor, Weeks Marine Inc.
Of those seven, one was a record length 7,357-ft crossing beneath the Elizabeth River and three were rare water-to-water drills under Hampton Roads Harbor that required the contractors to adapt to marine conditions.
It was a combination of the multiple crossings, water-to-water crossings and the challenges that the contractors overcame that made this the 2009 Trenchless Technology Project of the Year for New Installation.
Perhaps the most important water-to-water crossing was the 3,003-ft bore spanning the 53-ft-deep Newport News shipping channel, one of the world’s busiest commercial and military shipping lanes.
VNG senior project manager Les Flora, P.E., said HDD under the waterways was the only practical way to complete the marine crossings since governmental agencies would not grant permits for techniques, such as open-cut dredging due to environmental and shipping concerns.
Flora said, “The only way we could get a permit was to HDD… I’m sure that what the contractors have learned on this project will be of great interest to those in the industry.”
Flora said the project’s original design called for trenching across the majority of the harbor, but that plan was revised after entities such as the Army Corps of Engineers indicated that permitting would not be possible.
Instead, VNG looked to HDD techniques to cross the marine sections of the project, areas that include environmentally sensitive areas such as clam sanctuaries and oyster beds and shipping traffic that includes U.S. Navy ships that utilize the fueling station on Craney Island.
Flora said that by utilizing HDD techniques, the amount of material needed to be trenched decreased by about two-thirds the original planned quantity.
The marine environment created unique hurdles for the contractors to overcome: salt water that corroded equipment, strong tides and currents, storms and sonar equipment from passing ships and submarines that momentarily fooled with steering readings.
To combat against the conditions, Weeks customized its barges to support and secure the equipment Mears needed on the water. Weeks designed and installed a robust anchoring system and other equipment such as “goal posts” — steel pile structures straddling the pipe alignment in front of the barges that helped guide the pipe from the drill rig to the harbor floor.
On the water-to-water crossings, Mears’ 500,000-lb drill rig sat on a 350-by-38-ft barge with a four-point mooring system, a 250-ton capacity anchor winch and a 230-ton capacity crane. Next to that was a similarly large barge holding more than 700,000 gals of fresh water for the drill rig,
The drilling fluid systems used were Kem-Tron and TRI units. Guidance systems used were the Paratrack II system and Slimdril International’s Drillguide GST (gyro). Drilling fluids were supplied by MI Swaco and Bentonite Performance Minerals (BPM). A smaller crane barge supported a 140,000-lb rig at the exit holes.
To stabilize the drill barge during pullback, Mears Group project superintendent Mike Vidomski said Weeks deployed a three-anchor holdback system using a chain rated for 1 million lbs to anchor the barge, therefore counteracting the force of the Mears rig. The innovative use of a tension clamp on the drill string by Mears, together with the anchor system, stabilized the barge to perfection.
“When we were pulling pipe into the hole there was no movement on the barge,” Weeks Marine project manager Carolina Palmer said. “It was like we were on land.”
To improve steering accuracy for both the river and harbor crossings, the contractors also outfitted a mobile coil barge that floated on the surface above the path of the 9 7/8-in. drilling bit while Mears bored the pilot hole. The coil barge replaced Mears’ traditional method of placing wires on the seabed to create a triangulation that enabled the steering technician to track the precise location of the drill.
But even then, the team encountered a hurdle. When boring the channel crossing, the stringent regulations did not allow for the coil barge to be in the shipping lanes, forcing Mears steering technician James Eisenhauer and Vidomski to drill “blind.” The pair said they relied on the information they had acquired, but mostly their combined decades of experience in the field to drill the hole.
“You’ve got to rely on your gut library,” Eisenhauer said, referring to the experience built over a career. “We were able to hit accurately where we had to hit.”
Beyond the intricacies of HDD, the project also completes a practical purpose: It makes possible for VNG, a subsidiary of AGL Resources, to reach more customers and increase its ability to provide consistent service to customers in the Norfolk/Newport News area.
Flora said the project helps VNG reach three primary goals:
First, it increases reliability, since the pipeline will connect two previously separated sources of natural gas.
It allows VNG to handle a growing customer base. Flora said, “Capacity-wise, we are tapped out.”
Lastly, the project will allow VNG to take advantage of commodity prices and get the best price for its customers.
Flora said there were only two or three companies with the ability to complete the HDD portion of the project. Palmer said, “Many people didn’t go for the bid because it was a big challenge.”
Mears, however, took on the challenge. It is a company with worldwide reach and 28 drilling rigs with the capacity to install pipelines of up to 60-in. diameter and with pullback power up to 1.3 million lbs.
“Typically you don’t get projects where you have seven large bores like that,” said Mears Group project manager Craig Prout. “One of the challenges was the coordination of the launching of the pipe to pull back. Between ourselves and the marine contractor and onshore contractor, Bradford Bros., they had to launch the pipe to coincide when our hole was prepared to pull pipe back so it didn’t lay on the bottom [of the harbor] for extended periods of time.”
The first HDD drill Mears completed on the Virginia project was a 965-ft bore under the Lamberts Point Golf Course. In its next bore, Mears completed its record-setting 7,357-ft bore under the Elizabeth River. Mears used the coil barge to track steering since land-based steering mechanisms couldn’t be used.
The most recent set of bores crossed under Hampton Roads, and included the three water-to-water crossings and two shore approaches. In all, Mears drilled 15,439 ft, spanning the distance between Craney Island and Newport News, where the final shore approach is at Anderson Park.
In each of those drills, Mears used a 9 7/8-in. jet assembly to drill the pilot hole, a 500,000-lb drill rig on entry side and a 140,000-lb drill rig at the exit hole. The drill team mostly encountered clay and sand during drilling.
On the first Hampton Roads bore, the 3,004-ft Craney Island shore approach, the drill crew entered at 10 degrees on Aug. 18. Mears used a 26-in. hole opener, 36-in. reamer and 32-in. barrel reamer in a succession of reams to prepare the hole for the 24-in. product pipe. The exit angle was 8 degrees and product pipe was pulled through on Sept. 30, using the 32-in. barrel reamer front of the pull head.
The second bore started Oct. 25, 2008, with an entry angle of 8 degrees, marking the first water-to-water crossing for this project. Product pipe for the 3,547-ft Anchorage Crossing was pulled on Jan. 9 this year. Mears used 26- and 36-in. hole openers to increase the hole size and a 32-in. barrel reamer to pull the product pipe.
Next was the Middleground Crossing, a bore of 2,942-ft and also a water-to-water crossing, in which Mears used a gyroscope to navigate the bore. The gyroscope uses accurate sensors to establish measurements relative to true north and is not affected by magnetic interference. Mears entered and exited at 8 degrees The subterranean crossing started Jan. 19 and ended a month later.
The Newport News Channel Crossing, which spanned the busy shipping channel, started Feb. 25 and ended March 31. The 3,003-ft bore entered and exited at an 8-degree angle. It was the final water-to-water crossing for this project. Mears finished the Anderson Park shore approach, a land-to-barge drill set up next to a small baseball field in Newport News. That project started April 8 and finished April 29. Mears entered at a 14-degree angle and punched out at 8 degrees. At 2,943 ft , it was the final HDD bore for the project.
“Everything went incredibly smooth,” Prout said. “There was a lot of potential for problems and we were working during a rough time of the year, with regards to weather and we did have some shutdowns due to the weather conditions and high seas. But overall, Mother Nature was cooperative.”
Stephen Tait is a free-lance writer in Port Huron, Mich. Trenchless Technology contributed to this article.
Owner: Virginia Natural Gas
General Contractor: Weeks Marine
HDD Contractor: Mears Group, a Quanta Pipeline Services company
Pipeline Fabrication Contractor: Bradford Bros, a Quanta Pipeline Services company
Manufacturers: Kem-Tron, TRI, Slimdril International, MI Swaco and BPM