When Neal Jinkerson and Nick Walters began working for the pipeline construction division of Henkels & McCoy Inc. many 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,” says Jinkerson, area manager of western pipeline operations for Henkels & McCoy. He recently oversaw crews that worked from September to September to install 155 miles 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 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.
When the company was commissioned to install a 24 inch 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 miles of pipeline that would transport the natural resource from the Canadian oil sands in Fort McMurray, Alberta, Canada, to the Flint Hills Resources’ Pine Bend Refinery in Rosemount, MN, about 17 miles south of Minneapolis. The refinery is among the top processors of heavy crude in the United States and a leader in providing cleaner burning and high performance fuels. 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 miles of new pipeline, Henkels & McCoy crews were to build 155 miles, installing the 24 inch pipe with about four feet of cover. Starting in September, it took the crews a year and one month 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, being the ‘land of 10,000 lakes’ is not misstated. We had a lot of bog conditions,” says 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 to work in.”
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 jobsite. The disadvantage was difficulty in finding equipment that could cut through it.
“The frost in that part of Minnesota and in that time of year was as much as eight-feet deep,” Walters says. “Let’s say you have to have a six-inch bed, a 24-inch pipe and four feet of cover. Then you’re talking about a seven-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 had also 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 says.
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 the rockwheels to cut the ground deep and wide enough so that they could then excavate. Capable of cutting rock in depths up to 40 inches and widths ranging from 4 to 12 inches, 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 says.
Though smaller than traditional track tractors, the 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 says. “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 tractors’ 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’ unique 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 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 says. “With a huge trenching machine, you can only get so close and then you have to pull it out. Without these tractors, 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 inches 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 says.
Once the topsoil had been shaven off, the RTX1250 units followed, performing a couple of passes to open up the trench. While the rockwheel performed extremely well in cutting though the frost, one thing contractors must 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 says. “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 severe and the company was under great pressure to get this project done by deadline.”
Once the scarifier separated the topsoil and the rockwheel tractors 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 inch diameter crude oil pipeline on a 6 inch to 1 foot bed and then ensured it had about four feet 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 miles.
“I don’t want to be melodramatic. It’s dirt work,” Jinkerson says. “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 rockwheel was extraordinarily expeditious in allowing us to do that.”
FOR MORE INFORMATION:
Henkels & McCoy, 1-888-HENKELS , www.henkelsandmccoy.com
Vermeer Corp., (888) 837-6337, www.vermeer.com