In September, the City of Kenora and the Wauzhushk Onigum Nation celebrated the completion of a sewer and water system upgrade project that provides the First Nation with safe and reliable drinking water.
The interconnection of the community’s water and sewer system to the City’s system also meant that after more than three years, the Wauzhushk Onigum Nation is no longer under a boil advisory. The more than $14 million project was made possible by investment from Indigenous Services Canada.
While much of the project was completed via open-cut methods, the connection of the First Nation’s system to the City of Kenora’s required the undersea crossing of the 12-in. water line and the 8-in. sewer line using horizontal directional drilling (HDD). In all, the undersea crossings were each 120 m in length.
The open-cut work, mostly in the form of rock hammering and blasting was handled by the prime contractor Makkinga Contractors, of Thunder Bay. The HDD portion was sub-contracted to Staal Irrigation & Contracting, of Rosslyn, Ontario.
Serving Northwestern Ontario – mostly the 807 area code – Staal Irrigation & Contracting is a full-service utility contractor offering HDD, vacuum excavation, trenching, excavation, vibratory plowing, residential cable drops, aerial strand placement, aerial lashing, cable placing, anchor installation and fibre splicing. Despite having more than a decade worth’s of experience under his belt, Ian Staal, owner, notes that this installation is by far one of the more challenging that they have completed.
“Makkinga was performing a lot of rock hammering and rock blasting to put in mainlines for sewer and water and the services to each house in the reserve,” says Staal. “On the City of Kenora side that’s where we were working. We had to perform the two large rock bores into the lake.”
Knowing his crew would be drilling through bedrock, prior to submitting a bid on the project, Staal worked with Curt Dubbin, HDD division manager at Mincon, to determine what kind of equipment would best suit the job. As it stood, Staal knew he’d have to upgrade his drill to complete the work. Prior to this job the drill fleet at Staal Irrigation & Contracting included a pair of Vermeer D9x13s, a Vermeer D16x20 and a Vermeer D24x40. Staal knew where to turn. He called Paul Gauthier, product support representative at Vermeer Canada, and purchased a new Vermeer D40x55.
Staal notes that they needed the larger drill because when working with an air hammer system, a lot of the hammering is done by the compressor. But because they were upsizing to accommodate a 16- and a 12-in. host pipe, he needed a drill rig with a thicker rod to help support the weight of the large reamers. A thinner diameter rod could run the risk of breaking as the hammer works.
“We were set up 30 ft back from an existing sewer line in an easement adjacent to a residential property,” Staal says. “The work took us about a month-and-a-half, and it was actually some of the hardest rock we have ever dealt with. Makkinga was blasting [through the same rock] and in some spots had to blast two or three times to break up the rock. There were some veins that would be a little better, but most of it took us almost two hours, per rod, for the pilot bores.”
For both bores, Staal’s HDD crew —Devin Russel, Parker Livingston, Mitch McCall, Tanner House and Carson Smith — used a Mincon HDD50 to drill 5-in. pilot bores and then back reamed with a Mincon HDD80 and a 12-in. hammer attachment.
For the water line, the crew completed a second back ream with the HDD80 and a 16-in. hammer attachment. A third dream with a 16-in fluted reamer was necessary to clean out the bore and final pullback was with a 16-in fluted reamer and an attached swivel connected to ta 12-in. HDPE DR11 pipe. Things were a little less involved for the sewer line, which required second back ream with a 12-in fluted reamer and then a pullback with the 12-in. fluted reamer with a swivel attached to pull in the 8-in. HDPE DR11 pipe.
The first bore required some extra work on the crew’s part partly because of an unexpected challenge Staal and his crew encountered on this rock bore…a lack of rock. “We were drilling through rock and about 200 ft out [from the drill] just before going under the water, there was no rock,” Staal recalls. “We were 22 ft deep and the hammer started to jam up because it didn’t have anything to hammer against. We pushed through and once we got back into rock, and were able to get the hammer to go, the air pressure destroyed our borehole.”
As he explains it, when drilling in rock with an air hammer system, the air pressure helps move the rock cuttings out of the bore hole. That same air pressure, once they got back into the rock, started eating away at the 15- to 20-ft clay section and drew in soil from around the borehole. Things got especially tricky on the return trip when the reamer got stuck in the hole because it was jammed up with clay and there was no rock to drill through.
Quick thinking on the crew’s part, and maybe a little bit of luck, saved the day. Staal disconnected the string of rod at the drill, put on his normal earth drill head and pushed back down the hole until he felt clay. Using the earth drill head, he was able to excavate around the air hammer to rescue the tooling. The crew used their hydrovacs to suction back the spoils.
Going forward from that point, the rock drilling portions of the project used Cetco Insta-Vis and Versafoam drilling fluids and the clay portions used regular bentonite and clay cutter.
“We knew where that section was [on the first bore] and we fought with it each pass,” Staal says. “Even though we went deeper on the second bore to try and avoid it, it didn’t make a difference. That’s why we made the final pass with the fluted reamer to clean out the bore as best as possible so that the pipe could go through.”
With the bores complete, Staal and his team were able to turn over one of the most challenging HDD projects of his career.
“It was a great learning experience. It was an important project to get water to the community there,” Staal says. “Not too often do you see rock bores of this size. It was probably one of the more challenging ones that we have done. Product support from Vermeer Canada and Mincon helped make it possible. As did the hard work and perseverance of our employees throughout the job.”
Mike Kezdi is managing editor of Trenchless Technology Canada.