H D D intersects have really taken off in recent years, adding another dimension to the field of directional drilling. The lengths of these complicated projects continue to increase and they are starting to get the notice and credit they deserve in trenchless circles.
One such project garnered the attention of the selection committee in choosing the 2006 Trenchless Technology Project of the Year and it was a project that was brought to our readers earlier this year (February issue, pg. 44-45).
The Canadian province of Quebec, in the French-speaking city of Trois-Rivieres, 88 miles northeast of Montreal on the banks of the St. Lawrence Seaway served as the setting for the 2006 Trenchless Technology Project of the Year — New Installation.
Michels Directional Crossings Co., Brownsville, Wis., was the prime contractor for this project, completing the 7,456-ft intersect for 20-in. steel pipe during the harsh winter months in 2005. The purpose of the project was to connect utility transmission lines belonging to Trans Quebec and Maritime (TQM) Pipeline to an industrial power grid. The new pipeline will supply natural gas to a 550-megawatt cogeneration plant being built by Trans Canada Energy. The project owner was Gaz Metro, a natural gas supplier in Quebec, which will also use the lines for local distribution.
At the time of the project, Michels set an industry record for 20-in. diameter steel pipe at 7,456 ft, according to Michels design engineer Gregory Goral, who helped develop the pre-design drawings. The intersect method was implemented simply because the distance was too long for one drill rig. After a certain point, a single rig would no longer have the horsepower needed to provide the thrust and rotary torque required to cross the entire span through solid rock.
How challenging are intersects for HDD contractors? “It’s like trying to thread a needle in a thunderstorm,” Goral explains. “There are so many variables that need to be taken into account in performing a hole-intersect. Just the simplest human error of entering a coil coordinate incorrectly for the secondary tracking system could drastically impede the progress of a project of this magnitude.”
The intersect method employs two drill rigs that start from opposite ends of the project site and meet somewhere in the middle. In effect, one drill provides the pilot bore for the other.
One of the most difficult aspects encountered during the planning of this particular project was determining where the drills would meet, Goral says. The company factored in equipment capabilities, production time and length to determine the juncture.
“It took probably 400 to 500 ft to perform the intersect,” says Goral, explaining that one pilot hole had to be directed and drilled into the other as the drill bits converged. Michels monitored the progress using a secondary tracking system, which normally involves a guide wire laid along the ground to pick up a signal from the pilot bit.
However, ice and river traffic did not allow the wire to be laid across the surface of the river, says project director Mike Prior, vice president and general manager of Michels Directional Crossings Co.-Canada. Instead, the company used a coil in a non-metallic vessel to pick up the signal and determine the position of the drill head.
The Michels crew started drilling Feb. 15, 2005, from the north bank of the St. Lawrence. The company used a Michels Atlas 840, an 840,000-lb rig, and a Michels Hercules 1200, a 1.2 million-lb rig, to drill 160 ft below ground level, beneath the riverbed, starting with a 9 7/8-in. diameter pilot bore.
“The vast majority of the drill was mainly drilled through bedrock that ranged in compression strength from 3,000 to 8,000 psi,” Goral says. In addition to the shale bedrock, there was solid limestone.
The bedrock on the north side was approximately 100 ft below the surface. Michels installed 400 ft of steel conductor casing and used a telescoping method to drive the casing into the overlying soils. The diameter of the casing descended from 42 in. to 36 in. to 20 in. The bedrock on the south side was right at the surface and required only 40 to 50 ft of casing.
With the 840,000-lb rig set up on the north side of the St. Lawrence, crews drilled more than 4,800 ft until it reached the hole drilled from the south side.
Before the crews could begin drilling from the south side, Ganotec, the pipe support contractor hired by Gaz Metro, had to build a jetty out into the water to provide ground access to an island where the 1.2 million-lb rig was then staged. The drilling began Feb. 23, 2005.
The machine drilled approximately 3,375 ft toward the north site. The bore served as a pilot hole for the intersecting drill. The intersect procedure was completed March 8, 2005.
After the initial bore was complete, Michels reamed the hole to approximately 30 in., Prior says. The entry and exit points were opened to 32 in. Michels began and completed pipe pullback on May 5, 2005.
Contending with drastic fluctuations in the weather played a key role in modifying operations to complete the installation. At the north and south jobsites, Michels built large, hangar-size tents to enclose the area where the drilling took place, serving the crews, the machinery and the surrounding community.
“This proved to be crucial as weather conditions midway through the project expelled an Artic blast that provided some of the coldest weather on record at minus 45 degrees,” Goral says.
This cold blast was going to be used to Michels’ advantage when the crews were laying out the ParaTrack coil on the ice to aid in precise tracking and intersect operations during the pilot hole drilling. But that wasn’t the case.
“The cold weather necessary to freeze the mighty St. Lawrence Seaway came later than anticipated and provided no advantage to the pilot bore drilling and tracking operation,” Goral says. “Alternative methods were realized and used to assist in tracking of hole intersect operations.”
These tents also mitigated noise disturbances to nearby communities on the north side, Goral says.
Another obstacle for Michels was overcoming a language barrier in order to coordinate and support the drilling operations. “All initial documentation and specifications required translation and interpretation,” Goral says. “This made for some interesting meetings early on in the project prior to hiring interpreters. Bilingual workers were held at a premium and graciously accepted the added responsibility of interpreting for specific operations.”
Also, the English-speaking Michels crew and the French-speaking Ganotec and Gaz Metro crew met weekly during the project to discuss the progress. With the help of translators, the two companies were able to communicate with no problems, Prior says. During the project, some Michels employees even took the time to learn some French.
Another challenge involved bringing the Michels’ U.S. crews across the border and obtaining the necessary paperwork, work visas, etc. “Quebec is a very advanced Province and there exists a large workforce of highly trained people,” Prior says. “However, the skills required to carry out this project are quite unique and these skills were not available locally. We had to work through a long process before we were given approval to bring in our own skilled employees.”
How outstanding was this project? Goral sums it up. “The project set an industry standard for 20-in. diameter steel pipe at 7,456 lf in solid rock and was successfully performed utilizing the hole intersect method,” he says. “This project opened the door for the design and performance of longer HDD intersects.”
But Goral and Prior also point to the teamwork employed by all involved as a key to the project’s success. “There was a mutual admiration and respect gained between the crews, knowing that working together was the only way we were going to successfully accomplish this historic project,” Goral says.
Prior acknowledged the following in the success of the project: Robert Rousseau, project manager; Gabriel Pop, construction manager; and Jonathan Duguay, site engineer — all with Gaz Metro; Jeff Mueller and Cale Mullinex, Michels driller surveyors; and Marzia Frascadori, immigration lawyer and Tina dePetrillo, immigration paralegal.
Sharon M. Bueno is managing editor of Trenchless Technology.