Contractor bursts under and through stone, streets and homes to replace broken and blocked sanitary sewers in central Oklahoma
Combination fittings on mobile homes in three Oklahoma City parks tapped directly into 6-inch clay sewers blocked by massive root intrusions that cracked the hubs and pipes, causing backups. Broken fittings on some homes allowed wastewater to discharge on the surface.
Plumbers routinely snaked the lines and drilled holes through the worst impactions at huge expense to the previous owners. In places, the mains were no longer serviceable.
When the new owners learned that opencutting to replace the lines would cost twice as much as buying the real estate, they called John Johnson of Water Works Plumbing in
Oklahoma City. His company specializes in pipe bursting residential and commercial sewer lines.Using a 40-ton ram from Pipe Genie Mfg., the crew worked six months to replace the most critical lines with 6-inch HDPE SDR17 pipe. Besides roots, they fought a dense sandstone substrate and undocumented utilities without interrupting service to homeowners.
WHAT TROUBLE LOOKS LIKE
Throughout the project, Johnson’s plumbing crew arrived once or twice a day to unblock clogged lines and keep the sewers flowing, while his sewer team located problem areas with an inspection system from Vu-Rite Video Inspection Systems and NaviTrack locator from RIDGID. When roots blocked the camera’s progress, they opened a path with a RIDGID K-1500 sewer and drain cleaner, but even that bound up on some occasions trying to pass through the drilled holes.
Workers pipe burst 200 feet of mains in the first park, 1,600 feet in the second and 2,000 feet in the third. At each residence they used shovels to excavate the sewer, cut a hole in it, and ran temporary laterals from the stubs under the homes to the pipe.
On the second pull in the last park — 220 feet under three homes, two alleys and a city street — progress went from substantial to awful.
“The sewer lay on sandstone under 4 feet of sand,” says Johnson. “As it passed under the street for 40 feet, the compacted road bed was like granite around the pipe.”
Pressure on the 3,000 psi ram increased to more than 2,900 psi as the bursting head struggled to push the restricting soil aside. At 15 feet under the street, the head stopped moving, while the ram 200 feet away began pushing into the timber cribbing.
Johnson killed the power and called Pipe Genie inventor Gerry Robinson, who recommended spreading the pulling force over a larger area and setting the vertical timbers deeper.
“Naturally, it was Friday afternoon and those homes were still on a disconnected sewer,” says Johnson. “We pulled out the ram, brought in a sewage pump and bypassed the liquid to another main downstream.”
Johnson visited a steel scrapyard on Saturday morning looking for two 6-foot I-beams and a 4- by 6-foot by 5/8-inch-thick resistance plate. Meanwhile, Eric Howell widened the pulling pit to accommodate the larger plate, then he and Johnson jackhammered two holes in the sandstone at the head of the pit before setting the I-beams and plate with the excavator.
The pull resumed at 4 p.m. with the pressure on the ram hovering near maximum capacity. “As soon as the head crossed the street, the pressure dropped to 900 psi, which is barely more than an idle,” says Johnson. The last 180 feet went flawlessly.
Throughout the job, Johnson used an electrofusion processor (M.T. Deason) with Plasson ElectroFusion 45-degree saddle wyes on laterals and electrofusion couplings to join the separate pulls of pipe. Obtaining a variance from the state’s Construction Industries Board to use the saddles took three months, since the International Plumbing Code prohibits them on private laterals.
“They made all the difference in efficiency and integrity,” says Johnson. “We delivered a root-proof product with no seams or rubber gaskets.”
SUCCESS TAKES A TURN
Another uneventful run of 500 feet followed. “After that, I was convinced my men and the ram were bulletproof,” says Johnson. “Our next pull was 120 feet at a depth of 4.5 feet with a 90-degree turn centered under a mobile home. Although risky, I decided to pull through the 90.”
The pulling pit was 50 feet from the elbow. The job went smoothly until the 2.75-inch chain pulling the head tried to line up with the ram, came out of the elbow, and lodged somewhere in the sandstone. The pull stopped.
With only 18 inches of clearance under the home, workers increased the headroom by spending two days digging a 4-foot-deep trench to the elbow. Unable to leave the pipe running through a backyard, a privacy fence, and into the street, they severed it at the entry pit and relocated it. They also removed the ram, which allowed the sewer to flow while they worked.
Once the trench was completed, the crew used a Robert Bosch Tool Corporation rotary chipping hammer with a spade bit to excavate through the sandstone to the main. They used the camera to locate where the chain left the pipe and chipped down to it. At one point, it ran under a structural support beam.
The park manager sent his maintenance man to relocate the beam. “Every delay took half a day,” says Johnson. “The guys finally freed all of the chain and found the pulling head another 20 feet away under the home.”
Using shovels and the chipping hammer, the crew excavated a second pulling pit behind the home and aligned it with the lateral. After requesting a utility locate, they exposed a marked communications conduit, but nicked one of two undocumented electrical lines. A few sparks sent them dashing for safety. Several minutes later, sparks began arcing 10 to 15 feet high. It took the local utility all afternoon to repair the line.
The next morning, project manager Casey Hill drilled a 1.5-inch pilot hole from the second pulling pit to the elbow excavation to feed the pullback cable to the chain. His tool, a Hydro Bore from Pipe Genie, achieved 20,000 pounds of pushing power with a high-pressure jetting nozzle on the end of a hardened steel rod. As water from the RIDGID portable pressure washer blasted a hole through the sandstone, Hill threaded on 2-foot-long extension pipes.
To enlarge the channel, Hill and Jeremiah Gravitt switched to a Borit tool with a 3-inch backreamer bit attached to an industrial drill. Boring took the entire morning. Meanwhile, Jonathan Waite and Jason Dunn reassembled the ram and set the fusing machine in the entry pit. Reattaching the severed pipes was done with both ends in midair.
The pull from the second pit brought the bursting head up to the elbow. The crew then disconnected the ram, set it in the original pulling pit and reconnected the chain to the head to complete the run.
“We never expected to use every tool in our arsenal on the same job in the same yard on the same day, but it took that to see pipe moving again,” says Johnson.