FORT KENT, Maine — A slight miscalculation in construction of the new international bridge connecting New Brunswick, Canada, and Maine has created a headache for engineers and officials.
Workers on the project were installing a large metal wall, or “sheetpile” into the river on July 4 to create a cofferdam around the site of one of the new bridge piers.
In the process, a pipe carrying treated effluent from the Fort Kent wastewater treatment plant to the river was severed and its terminus destroyed, according to Jennifer Paul, Maine Department of Transportation construction manager.
The cofferdam, Paul explained Tuesday afternoon, provides a water-free environment for the contractors to pour cement for the bridge pier.
The sheetpiles fit together to form the walls of the dam and are driven down into the bed of the river.
“The contractor knew the pipe was there because it had been identified and located on the [design] plan,” Paul said. “GPS technology was used to locate it and we were told it was checked and double-checked before the [cofferdam] installation began and we are still investigating how this happened.”
Paul said the contractors, Caldwell and Ross LLC out of Fredericton, New Brunswick, were working on July 4 as that is not a holiday in Canada.
Because the effluent coming from the pipe has been treated in accordance with Department of Environmental Protection regulations, the mishap poses no environmental impacts, Paul said.
Members of the Fort Kent Town Council were briefed on the accident at their regular meeting Monday night.
“This has become our operational issue,” Don Guimond, town manager said. “Right now we have an effluent line in the middle of where there will be a pier [and] you can’t make a U-turn and go around it.”
The pipe, Guimond explained, runs to the middle of the St. John River where there is a consistent channel of running water throughout the year.
“The pipe needs to be in that channel to ensure adequate flow of the effluent,” he said.
The pipe terminates in what is known as a “wastewater outfall diffuser assembly” which helps disperse the effluent in a more efficient manner, Paul said. That unit was completely destroyed July 4.
“When they were digging out the cofferdam they thought they had hit a huge boulder,” Guimond said Tuesday morning. “They ended up lifting out the diffuser.”
Guimond said no one is blaming the contractor at this point.
“He had the plans and he had the designs,” Guimond said. “He was good to go.”
While Maine and New Brunswick officials continue their investigation into the accident, Guimond is left with a broken effluent pipe.
“It obviously has to be fixed,” he said. “In the meantime, effluent is still discharging, the treatment plant is fully operational and there is no backup of effluent detected.”
But he said experts will need to examine the damaged pipe to determine the extent of needed repairs.
The next step, he said, is figuring out where to reroute the pipe.
“At the end of the day we have to come up with a plan and design to go around the new abutment,” he said. “That plan must take into account the new pier.”
Any design and repair costs, Guimond said, will come from the state or province.
“We want to make sure the new design meets our standards and Maine and New Brunswick [departments of transportation] want to make sure it meets the bridge standards,” Guimond said. “At the end of the day we all want the same thing.”
Any design, Paul said, will be of the pipe alone.
“We need to reroute and relocate the pipe and diffuser outfall,” she said. “The bridge abutment location is not going to change [and] it’s easier to install a 12-inch pipe than move a bridge abutment.”
The accident did not stop construction work on the new bridge, which is set to open in August of 2014.