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Opponents of Enbridge Energy's Line 3 oil pipeline project are worried about the potential impact of the company's plan to temporarily pump as much as 10 times more groundwater out of the construction area than once planned.
Enbridge originally got permission to pump about 510 million gallons of water from the trenches it's digging as it replaces the current, aging Line 3 pipeline along a partly new, 340-mile (545-kilometer) route across northern Minnesota.
But the Calgary, Alberta-based company encountered more groundwater than it anticipated, and earlier this month it obtained a permit from the Minnesota Department of Natural Resources to pump up to nearly 5 billion gallons (18.9 billion liters) for the remaining 145 miles (230 kilometers) of pipeline it has left to build, Minnesota Public Radio reported Thursday.
Indigenous and environmentalist groups fighting the project say the pumping could harm groundwater quality and potentially affect sensitive wetlands, lakes and streams along the route — including culturally and economically important wild rice beds — which are already stressed by drought.
“Given that we find ourselves in a moderate drought, with higher than average temperatures and lower than average precipitation, displacing this amount of water will have a direct detrimental impact on the 2021 wild rice crop,” wrote Michael Fairbanks and Alan Roy, tribal chairman and secretary-treasurer of the White Earth Nation.
But the Department of Natural Resources says it determined that the increased pumping won't threaten groundwater sustainability or have other harmful impacts on natural resources.
The agency’s permit allows Enbridge to pump shallow groundwater only from the construction area, not from lakes or wetlands, said Randall Doneen, a senior department administrator who oversees ecological and water resources. The water is temporarily stored and treated, then discharged nearby, where it soaks back into the ground, he said.
Enbridge spokeswoman Juli Kellner attributed the need to pump more water in part to the company’s decision to use more wellpoint systems — a series of wells installed along the excavated trench that lower the shallow groundwater.
Wellpoints produce cleaner water with less dirt and sediment than using traditional sump pumps to get water out of the trench, said Kelton Barr, a consulting hydrogeologist who’s not involved in Line 3.
Enbridge's permit specifies that water removed from the construction trench cannot be discharged directly into a surface waterway, such as a lake or wetland. It must be run through a large fabric bag that filters out sediment before the water is discharged into well-vegetated upland areas or constructed stormwater ponds.