Mission Impossible

Plumbing America puts a new pipe bursting system to work on a severely misaligned lateral
Mission Impossible
Working in the alley alongside the garage, Rick (left) and Nick Thompson prepare the pulling pit for the PB-40 ram.

Interested in Relining/Rehab?

Get Relining/Rehab articles, news and videos right in your inbox! Sign up now.

Relining/Rehab + Get Alerts

Chronic backups, plumbing fixtures that never drained, and the overwhelming odor of sewage rendered the original section of an 80-year-old home in Gilroy, Calif., unlivable.

A plumber evaluating the situation discovered that the owners had built an addition with a deck and detached garage over almost 100 feet of the 4-inch vitrified clay lateral, and it was clogged with tree roots. Since digging up the line was out of the question, the contractor deemed the condition hopeless and walked away.

A referral from a builder led the homeowners to Plumbing America in Gilroy.

“We built our reputation on solving the impossible,” says owner Scott Thompson.

After viewing the plumber’s inspection video, which covered only one-third of the lateral because the camera was unable to navigate through a severe misalignment, Thompson knew that pipe bursting was the only solution. Using an untested hydraulic ram prototype, his crew overcame unexpected obstacles to replace the lateral and restore sanitary conditions.

 

Getting ready

Thompson’s crew of four used a Gen-Eye 2 camera system with digital locator from General Pipe Cleaners to inspect the lateral.

“I have never seen such a massive case of root intrusion in my life,” says Thompson. “They were green and so thick that it looked like a lawn in there.”

The men spent hours fishing the camera through the roots and fighting past the misalignment to the sewer cleanout in the alley.

“When all was said and done, it looked like a straight shot to us,” says Thompson.

Using a 320 Bobcat mini excavator, Rick and Nick Thompson dug the pulling pit on the far side of the garage and set the 40-ton pipe bursting system with 1-inch-thick resistance plate from RODDIE Inc. A 10 gpm/3,000 psi Quest Hydraulics pump powered the PB-40 ram with 31 tons of pulling force and 21 square inches of piston area.

“The unit is very compact, weighs about 120 pounds, and comes in three pieces so one man can transport them,” says Thompson. “Just pull some pins and the frame, hydraulic cylinder and gripper assembly come apart.”

Logistics

Armed with chipping guns, Paul Hart and John Sumner advanced on their stomachs in the crawl space under the house to dig the 36-inch-long launch pit. When they hit the lateral 18 inches below grade, they cut out a section and undermined two feet of the pipe.

“Undercutting that much of a shallow pipe prevents the pulling force from lifting it out of the ground,” says Thompson. “If the host pipe is going to move, you want it to go down. Once we have 24 inches of new pipe underground, the host pipe has enough cover to remain stable.”

Nick and Scott Thompson fused the 40-foot sticks of 4-inch SDR-17 HDPE pipe, snaking it under the house, across the length of the lawn and out to the curb. They attached the proprietary bursting head by tightening the bolt under the nose cone. The bolt grabs the inside of the pipe like an internal pipe wrench.

Meanwhile, John Sumner and Rick Thompson used a Speedrooter 90 from General Pipe Cleaners to cut a path through the tangle of roots, attach the 5/8-inch cable rated at 31 tons, and pull it back.

“Talking about the job goes a lot faster than the actual work,” says Thompson.

Field trial

The first 15 feet of the pull went easily, then the hydraulic gauges began registering high pressures.

“When the ram works really hard, the cable is beginning to stretch, so I paused to let everything return to normal,” says Thompson. “I tried two more times before the pressure dropped back to 6 or 7 tons and we were off to the races.”

Everyone assumed that the bursting head had passed through the misaligned segment until the pressure spiked again and held. Seconds later, two workers came running around the corner of the garage yelling, “Whoa! Stop! You’re wadding up the asphalt in front of the garage.”

The men excavated a pothole in the driveway and discovered that the cable had cut through a 45-degree bend and traveled 20 feet.

“We never recognized the elbow during the camera inspection,” says Thompson. “We assumed it was more misaligned pipe.”

When the crew dug under the house to locate the bursting head, they found that it had traveled a few feet, then wedged into a 24-inch-thick concrete slab encasing the lateral.

“We figured the contractor had poured the patch around the pipe after breaking it while excavating the foundation for the addition,” says Thompson.

The crew freed the head with chipping guns and restaged the ram in the driveway to pull the remaining 50 feet from the house. They then moved the equipment back to the pit in the alley and pulled the remaining 25 feet to the cleanout.

“That part was a piece of cake,” says Thompson.

After the men connected the lateral to the sewer and installed a new cleanout, the city inspected the job before the crew backfilled the three small pits.

“This job gave us two years of experience in one day,” says Thompson. “You can’t buy an education like that and the machine worked great.”

The client was pleased because he could once again use his large corner bathtub.



Discussion

Comments on this site are submitted by users and are not endorsed by nor do they reflect the views or opinions of COLE Publishing, Inc. Comments are moderated before being posted.