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Differences between Canadian, US GPS systems led to pipe damage

Julia Bayly | BDN
Julia Bayly | BDN
Crews continue to work on the new international bridge over the St. John River in Fort Kent Thursday, Sept. 6, 2012.
By Julia Bayly, BDN Staff

FORT KENT, Maine — A Canadian official has confirmed that differences between GPS systems in the U.S. and Canada were behind the international bridge construction error earlier this summer that severed a municipal wastewater discharge pipe.

The GPS coordinate system upon which surveys typically are based is different in the U.S. than in Canada, according to Judy Cole, spokeswoman for the New Brunswick Department of Transportation. The two systems can be reconciled through a mathematical adjustment, she said.

On the international bridge project, most of the survey was from the New Brunswick side with some from the Maine side of the border.

“In this instance, the survey from both sides came into play in the same location on the project without adjustment,” Cole said in an email. “As a result, a conflict between the pier construction and the [wastewater] outfall was not anticipated.”

The problem was not, as some have speculated, a failure to simply convert metric and standard measurements, according to Cole.

In early July, workers on the new international bridge connecting Fort Kent and Clair, New Brunswick, were installing a large metal wall, or “sheetpile,” in the river to create a cofferdam around the site of one of the piers.

The cofferdam 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.

In the process, a pipe carrying treated effluent from the Fort Kent wastewater treatment plant to the river was severed and its terminus destroyed.

GPS technology had been used to pinpoint the location of the discharge pipe, officials with the Maine Department of Transportation said at the time.

“The contractor [Caldwell and Ross LLC of Fredericton, New Brunswick,] knew the pipe was there because it had been identified and located on the [design] plan,” Jennifer Paul, MDOT construction manager, said in July. “GPS technology was used to locate it and we were told it was checked and double-checked before the [cofferdam] installation began.”

Because the effluent coming from the pipe has been treated at the Fort Kent municipal wastewater treatment plan in accordance with Department of Environmental Protection regulations, the mishap poses no environmental effects, Paul said.

However, doing nothing could lead to problems down the road for the new bridge.

“Having the pipe discharging directly above the abutments could cause erosion to those piers,” according to Mark Soucy, head of the Fort Kent wastewater treatment facility. “That’s really our only concern [and] once the new pipe is in and routed around that pier, there will be no problem with discharge scouring the structure.”

So government officials have been working with an engineer with Wright Pierce on plans to repair and re-route the pipe.

“Our focus has been to ensure [the pipe] is repaired and not on finger pointing on how it happened,” Paul said. “We are trying to push the repairs along as fast as possible.”

Bartt Booz, project manager with Wright Pierce, said, “We are about 80 percent along with those plans. The plans and specs call for the contractor working on the bridge to extend the pipe beyond the new pier and put in a new diffuser.”

That plan should do the trick, according to Soucy.

“I think this is a good avenue for fixing the problem,” Soucy said. “We are kind of limited on space and river levels so it is going probably in the only place we could put it.”

The new pipe will run straight down from the treatment plant, into the St. John River at its deepest channel and then detour around the new bridge abutment in a series of several right-angle turns before straightening out and ending at the diffuser.

“It has to go around the new abutment,” Soucy said. “The old pipe was right where that abutment is [and] the treated waste needs to be discharged below that point.”

There is more than enough pressure and flow, Soucy said, to push the liquid treated waste through those turns in the new pipe.

In addition, the new pipe will end in two wastewater diffusers instead of just one, per Department of Environmental Protection recommendations, Booz said.

When the pipe repairs will be done is a guessing game at the moment, Soucy said.

“I don’t think it will happen this year,” he said. “We are looking at time and we know the river [level] will come up any day now.”

Waiting a year will not harm the river or the discharge procedure, according to Soucy.

As for construction of the bridge itself, work is proceeding according to schedule, according to Claude Williams, New Brunswick minister of transportation and infrastructure.

“We anticipate the three piers to be finished by the end of November,” Williams said in an email. “The beams should start to be delivered and placed onsite at the beginning of December.”

For weeks residents have listened to the steady pounding of a massive pile-driver in use at the construction sight.

“We anticipate that there is about a month of [pile] driving to do in pier number-three, the one closest to the United States and in the south abutment,” Williams said in the email. “Once that is completed, we will be done with the [pile] driving.”

As winter nears, construction crews are working seven days a week on the new bridge and Williams said that will continue through September.

“We don’t expect to be shut down for long, if at all, this coming winter,” he said.

Cost for the $13.9 million project is shared between the two countries and three of the project’s five contract phases remain to be awarded.

Bids for the Maine approach — or ramp — to the bridge have been advertised and plans call for the New Brunswick approach to go out for bids next spring.

Bids for the demolition of the old bridge could be advertised in late 2013 or early 2014, according to NBDOT.

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