Pipe bursting project enables Park Service to replace aged infrastructure without affecting wildlife or damaging the environment.
The National Park Service was modernizing cabins and rehabilitating the wastewater infrastructure in Glacier National Park in Columbia Falls, Montana. HK Contractors in Idaho Falls, Idaho, won the bid for general contractor. HK hired only subcontractors with extensive experience working in sensitive areas.
“We were selected to pipe burst 2,000 feet of 6-inch mains,” says John Galligan, co-owner of Pipeshark in Elverson, Pennsylvania. “The contractor who cleaned and inspected them reported mostly terra-cotta with some cast iron pipe.”
Galligan, brother David and partner Steve Helms planned to transport their TRIC pipe bursting system 2,300 miles to Montana, but delays pushed the project into October. “Heavy snows had already closed the highway through the park,” says Galligan. “We had to get there fast, then rent equipment.”
Another trenchless company’s cooperation enabled Galligan to meet the tightened work schedule despite inclement weather, undocumented obstructions and stringent park environmental rules. “This was the company’s Super Bowl — our chance to put all our skills on the line to meet the challenges,” Galligan says.
Galligan planned to rent TRIC equipment from a local contractor or distributor, but found none in Montana. He turned to Rod Herrick, owner of Montana Trenchless, whose company was on the other side of the park. Herrick loaned him a RODDIE system — an R2 pipe bursting machine, portable hydraulic power pack, compact fusion welder and a John Deere D50 compact excavator.
Galligan also wanted the 6-inch DR11 HDPE pipe fused before their arrival, but found no one with enough experience to meet Park Service requirements. He had plotted the pulls and fusing areas using aerial photos from Google Earth, and planned eight pulls in five days, provided the pipe was fused beforehand. Doing it themselves added two days to the project and four more pulls as Galligan split longer runs.
The sewer fell 30 feet in elevation from the Swiftcurrent Motor Inn and cabins to the Many Glacier Campground and Hotel. Laterals from cabin blocks teed to dedicated 48-inch manholes.
“Another contractor had removed the structures,” says Galligan. “The excavations were adequate for pulling pits once we cut crisp 90-degree corners and a straight wall for the cribbing using a Sharp Shooter drain spade.”
The Park Service stipulated no trees be harmed, but the fused pipe often ran a slalom course between them. “We normally rest a 2- by 12-inch-long board against trees and let the pipe rub against it, but the rangers said no,” says Galligan. The men sank metal fence posts on either side of a path through the trees, then used digging bars at key points to direct the pipe as it snaked past them.
Under the gun
The mountains surrounding the Swiftcurrent Valley are high enough (elevation 8,000 to 9,296 feet) to create their own weather pattern, which cycled from misty rain to sleet to snow and back again for the first two days. The team fused pipe under a 10- by 10-foot canopy tent at the first five pull sites. “The 0.6-inch wall thickness of DR11 is twice that of DR17, so it isn’t as flexible,” says Galligan. “The cold made it even stiffer, giving us the worst of both worlds.”
Being forbidden to use large spotlights because they might affect wildlife exacerbated their difficulties. The men retreated to the parking lot where the pipe was stockpiled, and wore headlamps to work after dark. In the morning, they moved the fused pipe to pull locations.
“Working 14-hour days meant we arrived and left in the dark,” Galligan says. “We slept in a rented trailer 10 miles outside the park, and lived on oatmeal, peanut butter and granola bars because few facilities were open.”
The average pipe burst was 250 feet with the shortest 80 feet and the longest 450 feet. “Our first surprises were discovering most of the sewer was cast iron, then how extra heavy the material was,” says Galligan. “The sleek, lightweight R2 ram seemed like a sports car when we needed a Ford 350.”
The 19- by 12- by 15-inch-high bursting machine has 50 tons of pulling force at 4,700 psi, and a 22 mm cable rated at more than 50 tons. The 6-inch articulating bursting head immediately seats correctly in the host pipe, enabling the HDPE pipe to enter at the proper elevation with a shorter approach. A magnetic-assisted locking device connects the head to the welded end of the cable.
Wicked No. 6
The team’s reservations proved unfounded. The system cruised through the first five bursts in cobblestone soil at 8 feet per minute. The next downstream pull through 250 feet of cast iron pipe passed under trees, a road and into a manhole between two cabins with 18 inches of clearance per side.
“We never saw it coming,” says Galligan. “Suddenly, the ram began plowing through the soil toward a cabin. Full stop!”
The crew released the tension on the cable, then extended the side cribbing to better distribute the force of the pull. Their first attempt to break through the obstruction produced identical results. Using the SR-60 locator on a RIDGID SeeSnake, they found the bursting head in a gravel service area where excavation was allowed. The head was stuck in 15 feet of steel well casing.
“Freeing the head took some encouragement,” says Galligan. “We put a strap around the HDPE pipe behind the head and pulled back on it with the excavator arm, while we nudged the head with a sledge hammer.”
Once the pull resumed, the head traveled 20 feet and jammed in ductile iron pipe as it passed under a large pine tree in the middle of the service area. Any further excavation would damage its roots. With no cellphone service, Galligan emailed Herrick that night and requested a slitting blade to fracture ductile iron and steel pipes. Herrick said he’d fabricate one.
Batting a thousand
As the team set up the next morning’s 220-foot pull to a manhole, they looked up the cast iron line and saw it transitioned to a 4-foot length of steel pipe directly under a white birch tree surrounded by cabins. “By switching pits and pulling upstream, we had 215 feet of clear sailing before the head contacted the steel,” says Galligan.
When it did, the men removed the resistance plate, then built a 12-inch-wide space with 6- by 6-inch timbers to receive the steel pipe. With the plate against the new cribbing, Galligan started the ram and pulled in the last 6 feet. “The head locked into the steel pipe and out it popped,” he says.
The crew finished the remaining pulls while waiting for the slitting blade to arrive. Adam Shappell and Jeff Hanson from Montana Trenchless delivered the 13- by 8.5-inch-wide tool and helped with the pull. “We were surprised how well it cut through the ductile iron pipe,” Galligan says. “We liked the R2 system. It packs a lot of power and has many clever magnetic features.”