Twists and Turns

An adventure in Texas gets a restaurant back in operation
Twists and Turns

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A leaking 4-inch HDPE gas line under the main access road between an office building and parking garage at The Towers at Williams Square in Irving, Texas, posed a big problem for a restaurant operating in the building. With no gas, the restaurant had to hire caterers to provide food, so the staff was anxious to have repairs finished quickly.

Atmos Energy shut off the gas on a Thursday afternoon and the building engineer called plumbing contractor Robert Barones, owner of ARJ Plumbing Services in Fort Worth. Open-cutting would have taken too long, but Barones lacked the equipment for pipe bursting. Needing help, he called John Newell, owner of DigTec in Dallas.

“We arrived Friday morning and Robert asked if I could have the gas back on by 7 a.m. Monday,” says Newell. “I said yes, because the pipe was supposed to run straight under the road for 400 feet.”

It didn’t, and Newell spent the weekend working around obstructions that turned the job into much more of an adventure than was originally anticipated.


Subterranean secrets

Newell had experience bursting short runs of gas pipe and knew the difficulty.

“Pulling poly pipe inside poly pipe creates friction, and the heat melts the materials enough to fuse them together,” he said. “The correct bursting head would be crucial.”

HammerHead Trenchless Equipment representative Jeff Gabrielse shipped a poly pipe splitter by overnight express. After Newell’s crew closed one of two traffic lanes, they tried pinpointing the pipe but received no signal from the tracer wire. They moved to the basement delivery area and located where the gas line for the restaurant came through the retaining wall. Using a Kent pneumatic jackhammer on the boom of a TB135 Takeuchi tracked mini excavator, they broke through the concrete road and excavated down to the pipe with a 24-inch bucket on a second machine. Spoil was stockpiled behind the building.

Meanwhile, Newell jackhammered and excavated the 5-foot-square by 4-foot-deep pulling pit on the south end of the road 30 feet from busy O’Connor Boulevard, then set up the PortaBurst PB30 lateral pipe bursting machine from HammerHead. ARJ workers assisted with the setup and controlled the steady stream of delivery trucks and traffic flowing off the boulevard. Newell also made one excavation on the north end to expose the gas meter connection on the corner of the parking garage.

“Our plan was to run the B.E.S. FiberSnake duct rodder through the gas line and pull back the 3/4-inch cable needed for the burst,” says Newell. “At about 350 feet, the operator hit an obstruction.”

After marking the distance on the concrete, they hammered and dug until they uncovered a 90-degree elbow and the broken end of the tracer wire. With no idea of what they were up against, the crew chased the line with the two machines.

“Every time we thought we had the pipe going straight, we’d send in the rodder and it hit another elbow,” says Newell.

Two 90-degree bends, two 45s and 75 feet later, the pipe straightened out for the last 35 feet.

“Someone had rerouted the gas line around a grease interceptor and several fittings were leaking gas,” says Newell. “The detour created an 18-hour day.”


Strap the bad boy down!

Saturday morning, the crew continued excavations including the entrance pit behind the interceptor, and installed hydraulic shoring as needed where the line went through the basement wall. They also fused 40-foot sticks of 4-inch HDPE gas pipe while waiting for the splitting head to arrive.

“We had to keep the parking garage access open for the office personnel working that day,” says Newell. “ARJ assisted and directed traffic again, but we mainly had the place to ourselves.”

The 350-foot straight pull began soon after the splitting head arrived. Even with the head traveling at 1 to 2 feet per minute and using a polymer lubricating system, friction heated the pipes enough to begin the bonding process. Within 50 feet, the new pipe developed enough drag in the host pipe to pull it along. The pull stopped while workers rigged a restraining system.

They drilled holes in each half of the split pipe, bolted a length of flat plate to them and shackled nylon straps to the metal. The other end of the straps had rings.

“We ran grade 70 equipment boomer chains through them, then attached the chains to the D-rings on the front of the Ford 550 pickup truck,” said Newell. “I reversed until it pulled hard against the pipe, then put the transmission in park and set the emergency brake.”

The pull resumed and took four hours. At times, progress stopped as the pull sucked in more host pipe.

“That made me nervous,” said Newell. “So I put my trust in the equipment, cranked the machine wide open and pulled at the maximum 30 tons.”

The effort even dragged the truck forward, but the pull was successful.


Service restored

The line around the interceptor had to be replaced by hand, but the backfill was unstable sandy clay soil. On Sunday, workers constructed hydraulic jack shoring before Newell squeezed his 6-foot, 3-inch, 230-pound frame into the trenches to weld the pipes and elbows using a McElory fusing machine. Meanwhile, workers open-cut and replaced the remaining 35 feet from the interceptor to the connection through the basement wall.

A city inspector arrived at 6 a.m. Monday, passed the work and notified Atmos Energy to turn on the gas. Service was restored before 7:30 a.m. The crew backfilled and compacted the holes with spoil, squared the excavations with a self-propelled Core Cut concrete saw from Diamond Products, and cleaned up. Tuesday morning, the cement mixer arrived to restore the street. By Wednesday, life had returned to normal for everyone at The Towers.


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