When an oil tank farm need secondary containment, they turned to American cutting-edge technology and Canadian application skill for a cross-border industrial coatings project
BY JEN KRAMER
The North Dakota prairie is home to all manner of native species of plants and animals, including elk, antelope, whitetail deer, bighorn sheep, coyote, prairie chicken, pheasant, wild turkey, eagles, falcons, and the ubiquitous prairie dog. It is also a site for operations for the American oil and gas industry due to large deposits of oil deep below the rolling grass. Thus, a drive through the scenic area will reveal a stand of oil derricks methodically pumping amid the hills, while tank farms silently rise from the sweeping plain like steel ghost towns.
It was on one such oil tank farm that the secondary containment system was in need of replacement. Although the tanks themselves were in perfect condition, the fail-safe standing between the vulnerable grassland ecosystem and thousands of gallons of salt water that had been used in the oil drilling process – was in bad shape.
“The holding tanks for salt water disposal at the oil tank site were surrounded by a secondary containment system that was no longer working,” says Trevor Edmunds, President of Westoba Spray Foam. “The heavy plastic sheeting had torn and been subsequently covered with gravel, which had torn the plastic even further. It was in need of total replacement.”
The specification called for geotextile fabric coated with polyurea to create a durable, impenetrable shield between the base of the tanks and the surrounding area.
BIDS ACROSS THE BORDER
Based in Brandon, Manitoba, Canada, Edmunds was alerted to the job by his contacts at Rhino Linings. “We’ve been spraying oil field coatings for years up here in Canada. It took about six months to organize the paperwork to bid on the project in North Dakota,” Edmunds explains. “Then, when we won, I couldn’t use my Canadian crew. I had to put together a crew of U.S. workers. Also, because of my status as a Canadian citizen, I could only work as a Supervisor. I couldn’t actually spray the coatings myself.” This, however, was not a problem as Edmunds is used to supervising crews. He was able to quickly assemble a four-man spray crew made up of American talent. “It was an international venture,” Edmunds says. “And my American crew was spraying product from a great American company, Rhino Linings.”
ROCKY PREP WORK
Before the crew could even think about spray-applying any coatings, they first had to prep the area – that included removing the failed containment already in place.
“The entire containment area was approximately 10,000 square feet,” recounts Edmunds. “That meant we had to remove a lot of gravel and torn plastic before we could get to work laying out the geotextile fabric.”
Although the facility’s management would ultimately dispose of the waste, the Westoba crew had to load the loose debris, the gravel, and plastic into a vac truck, reducing the containment area to bare dirt.
“This removal process took about three days,” Edmunds says.
Next, it was time to place the geotextile fabric that would provide a barrier between the bare earth and the polyurea protective coating.
“We used a woven geotextile from U.S. Fabrics,” he continues, “because the woven material holds the polyurea better. But, laying out the fabric-like material was the most time-consuming part of the installation.”
Part of the containment enclosure is “wide-open” with no pipes or drains – just a flat area between the tanks and the berm of the enclosure. However, there are sections, especially in between the tanks, where every few inches a drain, a pipe, or a tank intrude on the straight run of the enclosure. When the crew would encounter one of these obstacles, they would have to use their knives to cut around it – just as if they were laying carpet.
KEEPING AN EYE ON MOTHER NATURE
To compound the situation, the weather started to turn. Already at the cusp of late summer when they began the job, North Dakota suddenly headed for an early – and wet – autumn.
Edmunds describes the situation, “As we were laying out the geotextile, it started to rain and we had to stop. The rainy days meant that we could not put it all out at once, but instead had to lay out sections at a time, spraying immediately after we placed the fabric.”
The crew determined the size of each day’s work based on the weather forecast, periodic temperature and humidity readings.
“Fortunately, we had some leeway because the Rhino polyurea that we were using can spray at higher humidity and lower temperatures than other polyurea that I’ve used,” Edmunds says. “But we still had to stop for rain.”
TIME TO SPRAY, EH?
The Rhino Linings’ polyurea specified for this project is Rhino Extreme™ 11-50 GT, a two-component, rapid-curing, elastomeric polyurea lining system. Before spraying, the crew first suited up in their personal protective equipment (PPE).
On either side of the border, Edmunds runs a very safe crew. “The guys that were spraying wore Allegro Fresh Air Systems with Fresh Air Full-Face Masks. Us non-sprayers wore Allegro half-masks. We all wore Tyvek suits, steel-toed boots, and hard hats. We also had Tool Box safety talks every morning with the facility representatives and the other trades that were working on site.”
Given that the containment area was already enclosed and cordoned off from the other trades, the crew did not have to worry about posting notices before spraying.
They were able to fire up Westoba’s Graco EXP25 Elite and using a Probler 2 air-purge gun attached to 250-feet of hose, spray 150 mils DFT of polyurea onto the geotextile. Weather permitting, of course.
Even though it was spray-applied in sections, the polyurea created a seamless, monolithic liner that can withstand heavy loads and vehicle traffic.
Because it is an elastomeric polyurea, it can withstand great vibrations and flexing, as well as the expansion and contraction that will come with the freeze / thaw cycling to be found on the North Dakota prairie. It also features great abrasion- and impact-resistance. As a secondary containment coating, Extreme 11-50 GT provides the ideal fail-safe to protect the surrounding grasslands.
Edmunds describes the installation process: “We would cut the geotextile, lay it out, and spray. The Rhino Extreme was tack-free in 10 to 15 seconds, with a full 100 percent cure in 24 hours, but it could be walked on in a few hours.”
This meant that when Mother Nature was willing to cooperate, the Westoba team was ready to spray.
“We were three weeks on the job, from start to finish. And the geotextile placement took the longest to accomplish because of all the pipes and drains,” says Edmunds.
The secondary containment in place, the tank farm is once again protected – as is the surrounding North Dakota grassland. Prairie dogs can burrow; turkey, pheasant, and prairie chicken can strut; eagles and falcons can soar; and the elk, antelope, whitetail deer, and bighorn sheep can all roam in a healthy habitat thanks to high-tech coatings and an international crew.