A portion of a large-diameter interstate crude oil pipeline that runs through Oxford and Addison townships (Michigan) is due to be replaced later this year by Canadian-based energy distribution company, Enbridge Inc.
Enbridge, Inc. will begin work on Oxford and Addison’s portions of what is known as Line 6B at some point between June 1 and Dec. 31, according to Jack Manshum, a spokesman for the company.
“That’s the plan as of right now,” he said. “We’re in the process of developing the construction timeline.”
Line 6B is a 285-mile crude oil pipeline that begins in Indiana, crosses southeastern Michigan and ends in Sarnia, Ontario, Canada. It serves refineries in Michigan, Ohio and eastern Canada.
This year, Enbridge plans to replace approximately 50 miles of Line 6B with new 30-inch diameter pipeline (the same size as the existing one) from Ortonville to the St. Clair River in Marysville. The portion that runs through Oxford is approximately 6.5 miles in length, while Addison’s portion is approximately 6 miles long, according to Manshum.
This is part of a much larger construction project that spans approximately 210 miles across Michigan and Indiana.
The Michigan Public Service Commission approved Enbridge’s application for this phase of the pipeline project on Jan. 31
“We’ve haven’t formally announced the details yet as to when we’ll be in each county or in each area,” Manshum said. “We’re in the middle of outlining that entire plan. So, I don’t know exactly when we’ll be in Oakland County.”
The old underground pipeline will not be removed to make way for the new one. It will be left in place.
“It will run parallel and adjacent to the existing line that’s in place now using the same right-of-way,” Manshum said. “When the new line is tied in and activated, the old line will be deactivated.”
Deactivation will involve purging all the oil from the old line and cleaning it thoroughly to remove any remaining crude, he explained. The old line will then be “taken apart in small segments” and capped.
“Each chunk of that pipe will have caps on it and then it’s filled with nitrogen,” Manshum said. “We will monitor the pressure inside that line as long as the line exists. The reason you fill it with the nitrogen and you monitor the pressure is to help make sure it doesn’t have any internal corrosion.”
With regard to the line’s exterior, he said Enbridge will maintain the cathodic protection that’s already on it to ensure there’s no external corrosion either.
Enbridge can’t simply walk away from the old pipeline.
“It’s a federal requirement,” Manshum said. “You have to maintain it as if you were using it.”
Manshum explained that leaving the old pipeline in place is “pretty standard in the energy transportation industry.”
“To completely take that line out of service, then replace it with a new one” is not practical for Enbridge’s customers, which are oil refineries.
“(The pipeline) would be out of service for six to 12 months – there would be no product flowing through (it),” Manshum said. “(The refineries) don’t have enough storage capacity to go that long.”
Once the new line is up and running, why can’t Enbridge come back and remove the old one? “That’s more of an inconvenience for landowners,” Manshum said. “We’re already there during one construction season, digging up their property, creating the trench.”
If Enbridge returns for another construction season, the workers will “basically redig everything that we just put back into place the year prior.”
Manshum noted it would involve the “same amount of time and process” to remove the old pipeline as it did to install the new one.
“It’s much less disruptive to landowners for us to only be in there once, instead of having to come back,” he said.