Contractor suspends directional drill by crane to avoid slowdown on project to stabilize bridge.


Davis Underground Solutions has handled its share of unique jobs, from installing drainpipe in a salad dressing factory to dealing with varying ground conditions.

In June, the directional drilling company based in Powder Springs, Georgia, was hired to help with repairs to a temporary bridge on a road construction site. At first it doesn’t sound too difficult, but add in the fact that they had to do it while the drill was suspended by a crane, and the difficulty meter shoots up.

“We had never done anything like this before,” says Matt Davis, owner and vice president. “It was a hurry-up-and-help-us type of phone call from the general contractor.”

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REPAIRING THE BRIDGE

Crews working on a two-year project to rebuild a bridge and roadway near Cartersville, Georgia, had put up a temporary bridge to allow traffic to move around the primary bridge.
Instead of using the typical fill under the temporary bridge — gravel and pressure-run pipe — a subcontractor backfilled using only dirt.

“With all the rain we’re getting this year, the dirt under the bridge started to erode,” Matt says. “The general contractor needed to do some tie-backs to ensure the structural integrity of that bridge.”

FIGURING OUT THE JOB

Matt got the phone call from the general contractor and once on the job site, he learned that crews would have to use a directional drill to push through a wooden wall on the side of the bridge, drill under the bridge and out the other side. Crews would then pull back 1 1/4-inch threaded rods.

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“They needed those steel rods in there to secure the I-beams because it looked like they were flexing out a little bit,” Matt says. “They had to tie those back into each other to hold them steady.”

Next, Davis Underground crews had to figure out how to position a Ditch Witch JT9 directional drill.

“Holes were cut into the walls on each side of the bridge and we had to set up our drill and shoot through those 6-inch holes and to the other side,” says Jim Davis, vice president of operations. “The problem was the holes varied between 7 and 15 feet high.”

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One of the first options considered was to haul in dirt to create a ramp and a flat ground surface to drive the drill up to do the work. But that would have required at least three to four more days on the job site and valuable time lost by the general contractor.

“As I was talking to the contractor I saw a crane off-loading a truck behind him,” Matt says. “There was another crane sitting behind me and I asked the contractor how much weight it could hold. He said plenty and I asked if it would hold 20,000 pounds. He said it could without a problem and at that moment he caught on to what I was thinking.”

SETTING UP THE DRILL

Crews loaded the drill onto a flatbed trailer and lifted it into the air using the crane (Link-Belt). One crew member stayed on the trailer with the drill to operate it, two other workers stayed on the ground to coordinate, and one worker stood on the ground above giving direction.

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“One of the toughest parts was just getting the drill stabilized with chains to the wall so it wouldn’t push the trailer back as we were drilling,” Jim says. “Every time we went to drill, it would push the trailer back before we got the chains to secure it.”

Davis Underground crews chained the drill to the ground on each side. Crews then found that as the drill pulled back the steel rods another problem developed. “It was pulling the trailer and the drill closer to the wall,” Jim says. “So we put the ramps on the trailer down and let them go against the wall to keep the trailer from moving to the wall as we pulled.”

COMPLETING THE JOB

It took crews two full days to complete the job with four different shots. Davis Underground had four workers on site the first day, and two on the second day.

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“Whoever cut the holes in the walls didn’t line them up exactly, so after we got the drill into the first wall, we had to steer pretty hard in order for it to come out in the right place on the other side,” says Jim. “We pushed through though.”

Matt was pleased with the work that his crews were able to accomplish. “It actually went very smoothly,” he says. “We got paid a pretty good price on it. It shows that a little bit of outside-the-box thinking and expertise goes a long way, and made a relatively tough situation into a simple solution.”


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