Trenchless Emergency: Auger Boring to the Rescue!
November 22, 2011Our Lady of the Lake (OLOL) in Baton Rouge, La., has been growing since forming 100 years ago as a private medical center. In any given year, the hospital treats more than 35,000 patients and 350,000 outpatients. The regional medical center has been gearing up for a $400 million expansion, including a new trauma center and multiple additions.
OLOL — already the size of a city block — is to grow even taller. The new 330,000-sq ft, nine-story heart and vascular treatment addition has an expected completion date of fall 2013. The large tower is located next to the Mary Bird Perkins Cancer Center and emergency room entrance.
Before construction could begin on 65-ft foundation pilings for the new tower, existing discharge drainage for storm run-off needed to be relocated. But because of the expansion’s location near the cancer center and emergency room, an open-trench method would be highly impractical. Joint venture-contractors JE Dunn Construction and Milton J. Womack and subcontractor Larry Graham Construction Co. approached Delco Services to review the suggestion for a 600-ft crossing of 36-in. pipe drilled at a .333 percent negative grade.
Del Harris, owner of Delco Services, reviewed the jobsite and determined that because of the restricted job area and shallow-nature of the bore path, two 320-ft auger bores would work best. The crew was to work at the midpoint, doing the first bore to the north on a negative grade, and then turning the machine 180-degrees to do the second bore to the south on a positive grade. After the completion of both bores, the machine was to be removed and a manhole installed at the boring chamber for the tie-in of the newly installed crossings.
Harris entered the trenchless industry in 2005 and purchased a Barbco 36-630 auger boring machine in 2009. Because of the specifics of the OLOL project and Harris’ inexperience with the machine’s accessories, he felt more comfortable having someone more familiar with the machine help out. So he called his friend Keith Guthrie, a former Barbco employee who now lived in southern Louisiana.
“Keith has a lot of experience in this business, and this was a big job for me and I wanted his expertise there,” Harris says. “And it surely paid off.”
Guthrie says he originally planned to just provide Delco with consultation services, but after options were discussed, Guthrie agreed to become more directly involved.
“When I arrived to the site, I was amazed at the constraints of the site, the logistics involved for operations and the fact that our only access to the site was through the main entry to the emergency room and cancer center off a major six-lane thoroughfare,” Guthrie says. “Every 20-ft segment of casing had to be retrieved two at a time from more than a half-mile away.”
The work-area was incredibly small and tight; work on the first bore began July 11, and the pressure of the worksite’s surroundings was immediately felt.
“It was next to impossible to get the trucks and equipment in and out every time we had to move a piece of pipe,” Harris says. “Usually you’re doing these bores out in an open field or pasture underneath railroad tracks and nobody bothers you. I had two guys there [at OLOL] full-time just directing traffic. They stood out there all day. Every time we had to make a move, we had to go out there with flags and orange vests and direct traffic so we could get the equipment in and out.”
On the second day of construction, the six-member crew was told an independent inspection firm would be inspecting each weld to the casing. The welders completed a weld test certification and construction was restarted.
“We finally figured out how to get everything in and out as we had to haul off every cubic yard of spoil from the site, placing a tandem axel dump truck on location, just adding more constraints to the site,” Guthrie says. Because of the size of the work area, Delco had to rent smaller equipment, and a mini excavator was used to assist in spoil removal, adding even more congestion to the site.
Concerned with limiting emergency traffic to the hospital, the Delco team considered doing construction at night when things were calmer and could also provide the workers with relief. Guthrie says every appropriate measure was taken to prevent obstructions, but often it was inevitable. Things were compounded when Louisiana’s July weather set in: 110-degree days and the constant threat of thunderstorms.
“It was just like every time we got things going our way, some new obstacle was placed in front of us,” Guthrie says.
Once the first bore was completed, Harris and Guthrie expected to be better prepared for the second, but new issues stood in the way. The oncology lab at the cancer center was set to be demolished, so four double-wide trailers were used as temporary offices in the center’s parking lot. The trailers were directly over top the proposed bore path, and the primary electrical supply to the cancer center and temporary units intersected the bore path. Delco delayed construction for two days in between the bores to do a better investigation of the proposed elevations and to ensure no electrical difficulties.
“The second bore had to be timed when we started because they wanted us to be at the electrical line on a Saturday morning,” Harris says. “They didn’t want to shut [the cancer center] down on a weekday. They have very minimal business on the weekend, so they wanted us to start the bore on Monday, average two pipes a day and be in a position on Saturday to cross that electrical line.”
Guthrie says the two hours the electricity was disconnected were stressful.
“We were given a two-hour window to intersect their lines,” he says. “As tension grew, we got to that area and pushed forward. Everything went well.” Power was restored and the second bore was finished on line and grade. The project was completed within three weeks.
Harris says the significance of the project was understood by all involved.
“We were appreciated by the all the contractors involved,” he says. “They came to us and told us how well we performed regarding safety, efficiency and dealing with all the headaches. We did it with a good attitude, hustling the work through and knocking the job out.”
Everyone was glad to complete this project without posing a threat to the hospital or its patients.
“Because of trenchless technology, we were able to do this job without shutting down the entrance to the emergency room or the cancer center,” Harris says. “That was critical. The boring technique allowed no disturbance to the hospital.”
Kelly Pickerel is assistant editor of Trenchless Technology.