Striking Success

A pipe-bursting project enables a bowling alley to repair a kitchenette drain line in short order with minimal disruption to the property or business operations

A slow-draining 4-inch line in the kitchenette of the Diablo Lanes Bowling Alley in Concord, Calif., backed up despite the efforts of All Service Plumbing in San Ramon, Calif. A video inspection revealed a severely corroded cast-iron pipe.

All Service, considering the purchase of pipe-bursting equipment, contacted John Rafferty at TRIC Tools Inc. in Alameda, Calif., to evaluate the situation and possibly turn the job into a demonstration training session.

“I saw nothing unusual about the work, but the logistics were challenging because the pulls would occur inside the building,” says Rafferty. “The collapsed line ran under the bowling lanes, sports lounge, cafe and pro shop before tying into the lateral. It turned 90 degrees under the arcade, then jutted another 15 feet out of the building to the grease trap under the sidewalk.”

Weekends and nights were the busiest times, and the owner wanted the restoration completed during slower hours and before the weekend. Tight coordination between Shelly Samson of All Service Plumbing and Rafferty, and the cooperation of bowling alley staff, enabled the job to be completed on time.

Zip service

As the subcontractor, TRIC would fuse 20-foot lengths of 4-inch HDPE SDR-17 Drisco pipe and pull it into place. “To perform our zip service, everything else must be ready when we arrive,” says Rafferty. “As is always the case with pipe bursting, 90 percent of the work is preparation. We couldn’t afford any delays if we were to finish before the crush of Friday night bowlers showing up.”

Samson’s four men arrived at 5 a.m. on Friday to excavate the entry and exit pits. They first rolled plastic sheet over the carpet at each entrance and along the work path. To contain the dust inside the building, they enclosed one-third of the arcade in Mylar, then cut through the tile and concrete floor with a ceramic saw blade. They hand excavated the 3-foot by 4-foot by 3-foot-deep pit with shovels, stockpiling the sand on tarpaulins.

Cutting through the sidewalk over the grease trap, the men dug a 3-foot by 6-foot by 3-foot-deep entry pit about 5 feet from the building’s foundation, taking all necessary precautions to protect the public. Enclosing the pull pit in the kitchenette was impossible, as the 2-foot-square hole went in the narrow walkway between a sink and gas range.

When Rafferty and assistant Robert Ding arrived at 8 a.m., they brought in materials through the bowling alley’s side door so as not to obstruct customers. “We laid the pipe along the wall of the sports lounge and set up traffic cones so people wouldn’t trip over the sticks,” says Rafferty. “It was amazing how little attention anyone paid us.”

Setting up and fusing each joint using the Connectra 14M butt fusion machine took 15 to 20 minutes, including cooldown. “We couldn’t fuse outside because we’d be unable to position the 100-foot length,” says Rafferty. “The pipe had to curve through the doorway from the sports lounge into the arcade.”

The next challenge was stringing the pulling cable through the collapsed line. Ding navigated the 15 feet from the hole in the sidewalk to the arcade pit using a 1/4-inch fiberglass duct rodder on a reel. Once the rod popped out, Rafferty attached a 3/4-inch standard swaged cable rated at 36 tons. While the All Service Plumbing crew observed, Ding retracted the rodder and attached the cable to the pulling head on one length of pipe.

Flying blind

The soil in the arcade pit was mushy from the leaking line. To support the 24- by 24- by 1-inch thick aluminum resistance plate, Ding drove four 1 1/2-inch galvanized fenceposts next to it, then set the TRIC HPLS-20 (high-pressure lateral system) 20-ton ram on top of the pulling base.

A two-stage electric Power Team pump rated at 1 gpm/8,000 psi powered the ram. “The little pump was noisy, but produced no fumes,” says Rafferty. “Fortunately, the pull took only 15 minutes.”

The mushy soil made it difficult for Rafferty to see when the bursting head arrived in the hole. “We pulled extra slowly so as not to wrap the cable termination under the take-up wheel or crash the head into the resistance plate,” he says.

When only 5 feet of pipe protruded from the entrance pit, Ding ran inside to alert Rafferty, who shut off the pump. “We dug through the mush and found the head already in the hole,” he says. After disengaging the cable and removing the ram, Ding pounded the pipe home using a sledgehammer.

The soil in the kitchenette pull pit was the same mushy mess, so Rafferty pounded in two posts to stabilize the resistance plate. The arcade hole now became the entrance pit, and the pipe ran 85 feet under the slab past the pro shop, cafe, sports lounge and main entrance.

Customers were bowling, and the staff first cleared the south half of the lanes. Enough lanes were open so that no one minded moving. “We were more a source of amusement than annoyance,” says Rafferty.

Path of travel

Rafferty explained the pipe’s travel path to the staff: how it would curve to enter the pit, and how many lanes he would need to complete the maneuver. Since they knew where to walk on the lanes, he asked them to hold the pipe to avoid damaging the surface.

The staff rallied to the call. “It was quite a ballet, because they had to back up and go forward several times to properly align the pipe while steering clear of obstacles,” says Rafferty. “Supporting the pipe during the pull resembled a line dance with a boa constrictor.” To achieve the correct entry angle as the pipe approached the pit, Rafferty elevated it over a stepladder. An All Service Plumbing employee guided its journey.

Because they could put a pump outside and run the hose and control wire through the kitchenette’s back door, Rafferty selected a two-stage Enerpac hydraulic pump rated at 2.5 gpm/8,000 psi and powered by a 5.5-hp Honda engine.

“The soil was soft and the pipe was rotten, so we used less than four tons of pulling force to burst it,” he says. “The shorter pull used even less. They went very quickly.” During the long pull, however, Rafferty asked the bartender to stop using her bar sink, as the liquid was running into the pulling pit.

All Service Plumbing connected the pipes using standard mechanical couplings. The line was back in service and the floor cleared just as the Friday night crowd of bowling enthusiasts arrived.



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