‘Strait’ talk from Enbridge rep
MARQUETTE — Enbridge Line 5 is intact and the company has plans to reinforce the damage to the pipeline in April.
Enbridge U.S. Government Affairs Director Peter T. Holran told a group of stakeholders during the U.P. Energy Summit on Wednesday that the company had confirmed that the pipe had sustained several small dents ranging from 2.5 to 4 percent but had not been punctured, nor is it in danger of being punctured.
“In the integrity world, the way that we look at our pipes anything up to about ten percent starts to cause us concern about the integrity of the pipe,” Holran said. “So we were fairly comfortable that there was not an integrity issue with the pipe, further tests throughout the last couple of weeks confirmed that. We have done the temporary repairs. In other words we have inspected the dented areas, confirmed that there is not an integrity issue, prepared them for a permanent type of repair.”
The line, built in 1953, moves 23 million gallons of oil and natural gas liquids per day through the Upper Peninsula, splitting into twin, underwater pipelines through the Straits, before returning to a single transmission pipeline through the Lower Peninsula and on to a hub in Sarnia, Ontario.
The pipeline continues to operate, but at a reduced pressure, Holran said.
“This tracks with federal code that if we had an immediate repair that had to be made we would have to take a pressure restriction on the pipeline,” Holran said. “We took those voluntarily back in April just to make sure that we were doing everything we could to safeguard the pipes.”
The company is working with the U.S. Army Corps of Engineers and Michigan Department of Environmental Quality to conduct repairs on the areas damaged by the dents.
“What we are planning to do, once the permits are approved is put a composite sleeve over the areas that were impacted. This will allow us to reinforce those areas of pipe and in our minds bring the integrity of the pipe back to as if it had never been dented at all,” Holran said. “To do that, we need to actually get 360 (degree) access to the pipe. We need to be able to wrap it in this composite material.”
The damage to the pipeline is believed to be related to an alleged anchor strike which also damaged two out of six high voltage cables owned and operated by American Transmission Company that deliver electric power to Michigan’s upper and lower peninsulas..
Prior to the April 1 incident, the cable network consisted of of six separate cables, ATC Director of Asset Maintenance and Commissioning Jared Winters said, that together make up two electrical circuits. Each of the 138-kilovolt cables consists of copper conductors protected by layers of neoprene, lead and exterior galvanized steel wires. Inside, dielectric fluid is pumped through small gaps inside the cable, with the fluid acting as an insulator.
The strike, which is believed to have happened on April 1, caused two ATC lines to be completely severed and caused an estimated 600 gallons of toxic dielectric fluid into the straits before recovery efforts began, according to an April 24 MLive article.
Winters said the cables are no longer leaking, and ATC has adapted to the damage.
“What we did to respond and repair the cables, we had bring each end of the separate cables on a barge and then we capped each of the cable one at a time and lowered them back to the lake bed in the pre-event location,” Winters said. “We also installed concrete anchor mats on top of the other two cables to prevent them from moving in the future.”
He said the company has inspected and tested the undamaged cables, and three of the undamaged cables have been reconfigured to energize one 130 kilovolt circuit.
“Our plan is to replace the cables using solid dielectric cables which would not contain any liquid,” Winters said.