When Neal Jinkerson and Nick Walters began working for the pipeline construction division of Henkels & McCoy Inc. years ago, there was a distinct time frame for what constituted the construction season. But in recent years, as equipment has evolved, the construction season has become year-round.
“The longer I’ve been in the business, there’s really no construction season anymore,” said Jinkerson, area manager of western pipeline operations for Henkels & McCoy. He recently oversaw crews that worked from September to September to install 155 mi. (249 km) of crude oil pipeline in Minnesota.
Being in business since 1923 means that Henkels & McCoy has been asked to complete all types of projects. With more than 6,000 employees in more than 80 offices located from New England to Hawaii, the company is one of the largest privately held engineering, network development and construction firms serving the communications, information technology and utility industries.
So when the company was commissioned to install a 24-in. (61 cm) crude oil pipeline in Minnesota during the dead of winter with wind chills dipping below minus 50, its employees dusted the snow off their boots and rose to the task.
Improving Oil Flow
To service the state of Minnesota with additional crude oil, Minnesota Pipe Line Co. set out to construct 304 mi. (489 km) of pipeline that would transport the natural resource from the Canadian oil sands in Fort McMurray, Alberta, to the Flint Hills Resources’ Pine Bend Refinery in Rosemount, Minn., about 17 mi. (27 km) south of Minneapolis. The refinery is among the top processors of heavy crude in the United States.
The refinery, which is operated by Koch Industries Inc., processes the crude oil into petroleum products such as gasoline, diesel, propane and butane. Petroleum products produced at the refinery are mainly used in the Upper Midwest. It also manufactures asphalt, heating fuels, and sulfur for fertilizers in addition to supplying much of the jet fuel used at the Minneapolis / St. Paul International Airport.
Of the 304 mi. of new pipeline, Henkels & McCoy crews were to build 155 mi., installing the 24-in. (61-cm) pipe with about 4 ft. (1.2 m) of cover. Starting in September, it took the crews 13 months to tie in the product and complete the project.
Whether it’s summer or winter, Minnesota’s landscape can pose problems for construction crews.
“In Minnesota, it being the land of 10,000 lakes is not misstated. We had a lot of bogged conditions,” said Walters, who served as project superintendent on the job. “Actually, the severe cold helped us in the winter because a lot of those wetlands in the spring would have been almost impossible.”
But the winter also posed its own special challenges. The advantage of the ground being frozen is that it allowed Jinkerson and Walters to more easily position and maneuver their equipment on the job site. The disadvantage — it was difficult finding equipment that could cut through it.
“The frost in that part of Minnesota and in that time of year was as much as 8 feet deep,” Walters said. “Let’s say you have to have a 6-inch bed, you have a 24-inch pipe and then you have to have 4 feet of cover, you’re talking about a 7-foot excavation. It couldn’t be done without cutting the frost.”
Rockwheels — Not Just for Rock
At first, they tried a bulldozer with a ripper attachment, but the ripper was unable to penetrate deep enough and score the ditch adequately to where crews could then excavate. They also had contemplated using a traditional trencher or ditch machine, but decided against it because the equipment’s bulkiness and heavy weight prevented it from being easily moved from location to location.
That’s when Jinkerson and Walters took another look at the company’s arsenal of equipment and settled on the Vermeer RTX1250 quad-track ride-on tractor with a rockwheel attachment.
“Henkels has several of these machines in its equipment fleet, but none of them were available when we needed them, so we had to rent all of them,” Jinkerson said.
Rockwheels are typically used to cut rock, but Jinkerson hoped the attachment would work just as well on frozen soil. All they needed was for their four RTX1250s’ with the rockwheel attachment to cut the ground deep and wide enough so that they could then excavate. Capable of cutting rock in depths up to 40 in. (102 cm) and widths ranging from 4 to 12 in. (10 to 30 cm), the machines’ shank rotary carbide teeth help increase cutting performance in tough conditions.
“The rockwheel is thin, so we had to make a couple of passes with it. It would open up the trench, and then we would clean the trench with the excavator and obtain our required depth requirements,” Jinkerson said.
Though smaller than traditional track tractors, the four RTX1250 units were able to effectively cut through the frost and boast some big production rates to help Henkels & McCoy stay on schedule. The machines’ direct drive motor systems help increase cutting efficiency.
“On good days, we came close to trenching 3,500 feet per day in severe winter conditions,” Walters said. “All days are different. Some days we didn’t get much, and on other days it really opened up.”
And when it came time to tie in the pipe, the RTX1250s’ maneuverability proved beneficial. Jinkerson and Walters utilized the machines to help dig out a large bell hole for access to welding the pipe. Because of the machines’ quad-track design, crews were able to approach and position the units along the edge of the ditches and road crossings. The quad-track system on the Vermeer RTX1250 has relatively no breakover point, which allows for full power to all four tracks and maximizes tractive effort and stability by maintaining four-point contact with the ground.
“Again, a traditional track tractor trencher would have been great in some instances, but we could not have moved it to a tie-in area,” Jinkerson said. “With a huge trenching machine, you can only get so close and then you have to pull it out. Without the RTX1250s, we would have been stuck with hammering or pounding out the dimensions of the bell hole with either a hammer or some other inefficient tool.”
Success in Three Steps
Once Henkels & McCoy crews had chosen the right equipment, it would seem everything else would fall right into place. However, the arctic temperatures and resulting ground conditions continued to pose challenges for the team during the winter months.
As they began cutting the ground with the rockwheel, they soon realized they would need to separate the topsoil. To do this, Jinkerson and Walters chose a scarifier to trim off the first 8 to 12 in. (20 to 30 cm) of topsoil in the rural areas where much of the work was being performed.
“In agricultural areas it’s extremely important to perform topsoil separation because you don’t want the topsoil and subsoil melding,” Walters said.
Once the topsoil had been shaven off, the RTX1250 units equipped with the rockwheel attachment followed, performing a couple of passes to open up the trench. While the rockwheel performed extremely well in cutting though the frost, one thing the contractors had to keep in mind is that ice affects the attachment’s steel carbide teeth much differently than rock.
“When you’re cutting ice, steel temper in the teeth is devoured,” Jinkerson said. “It’s not that the teeth aren’t functional, it’s just that they’re designed to cut rock. We were changing teeth almost every day. But if we didn’t do it, we didn’t get any production.
“The weather conditions were so severe, and the company was under great pressure to get this project done by deadline. We were able to continue in these severe conditions in part because of the Vermeer rockwheel,” Walters added.
Once the scarifier separated the topsoil and the RTX1250s opened the trench, the traditional excavators were brought in to complete the final part of the three-step process. Meeting their trench requirements, Henkels & McCoy crews installed the 24-in. (61 cm) diameter crude oil pipeline on a 6-in. to 1-ft. (15 to 30 cm) bed and then ensured it had about 4 ft. (1.2 m) of cover. Day in and day out during the summer’s hottest days and the winter’s coldest months they repeated this process over 56 weeks for 155 mi. In the end, the job was a success because crews completed their portion of the project by deadline, enabling additional millions of barrels of crude oil to begin flowing through the pipeline to serve the Upper Midwest.
“I don’t want to be melodramatic. It’s dirt work,” Jinkerson said. “The ground conditions were frozen; we had to come up with a viable means of cutting the soil and opening up the ditch; and the Vermeer rockwheel was extraordinarily expeditious in allowing us to do that. Without it, we wouldn’t have gotten the production we did.”
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