ST . PAUL -- The Minnesota DNR recently responded to concerns regarding Enbridge's water use permits for the Line 3 replacement project amidst drought-related surface water appropriations suspensions throughout the state.
"The Minnesota DNR is aware of some concerns and confusion related to Enbridge’s water permits for the Line 3 replacement project and the company’s current construction activity," a release said. "We currently have no indication that the company is operating in violation of any of its water appropriations permits, and we are monitoring compliance on an ongoing basis."
Many have asked how Enbridge is continuing with construction given drought-related restrictions on its water appropriations permits. The DNR has temporarily suspended surface water appropriations for some permittees in watersheds where flow conditions meet certain triggers. These suspensions include Enbridge’s water appropriations for dust control, horizontal directional drilling, or HDD, and hydrostatic line testing in some locations. Enbridge’s surface water use is currently under suspension in Crow Wing River, Pine River, Mississippi River - Brainerd, and St. Louis River watersheds.
The DNR has not suspended Enbridge’s HDD activity itself in these watersheds, or elsewhere, due to drought conditions. Much of the pipeline route traverses areas where water appropriations permits are not currently subject to suspension, the release said.
Within the watersheds where Enbridge’s surface water use has been suspended, the company may continue to conduct HDD activity if it is using stored water previously appropriated, or if it obtains water from another appropriate and available source.
"The DNR continues to monitor and manage the drought situation statewide in accordance with the drought management plan," the release said. "Temporary suspensions or modifications will be carried out as necessary."
Another concern has been Enbridge being allowed to continue its trench dewatering in watersheds where its water permits have been suspended.
According to the release, an amended water appropriations permit was granted to Enbridge for trench dewatering on June 4. This permit allows Enbridge to pump and temporarily store groundwater in order to keep construction trenches dry. The DNR’s water permit suspensions apply to surface waters, not groundwater. Groundwater permits are not generally suspended during a drought, unless there are specific concerns, such as impacts to associated surface waters or well interference issues.
By nature, trench dewatering is only needed when groundwater accumulates in a construction trench. The water is stored, treated and then returned to the area near the construction activity, where it seeps back into the ground and the water table.
The dewatering activity occurs over a few days at any one location. Any localized impacts to natural resources due to the temporary lowering of the water table are short-term and minimal, the release continued.
The Enbridge groundwater appropriations permit that was amended on June 4 allowed an increase in the volume of temporary dewatering from 510.5 million gallons to approximately 4.9 billion gallons. This volume is for the entirety of the pipeline route.
Prior to granting the amendment, the DNR evaluated the requested volume increase and determined it would not threaten groundwater sustainability or have other unacceptable natural resource impacts.
To the extent current drought conditions are affecting the water table along portions of the pipeline route, the company’s dewatering needs may be lower than anticipated. For example, if the water table is lower due to drought, the company won’t need to pump and store as much groundwater to keep excavation sites dry.
"The Minnesota DNR will continue to monitor the situation and will suspend or modify the amended construction dewatering permit if conditions make that necessary," the release said.
For more information and updates on Enbridge's water use permits, visit www.dnr.state.mn.us/line3.