The Maine Department of Environmental Protection plans to hold a public hearing on March 25 on a proposal to build a layover facility for Amtrak passenger trains in Brunswick.

The department has yet to find venue for the hearing.

The Northern New England Passenger Rail Authority, which managers Amtrak’s Downeaster service between Boston and Brunswick, has applied for a storm water permit, the only remaining approval the authority needs before it begins construction.

The layover facility has been contentious for a number of years. The rail authority has said it needs the facility to expand service and to make more efficient use of its trains. Opponents say a layover shed is inappropriate near a residential neighborhood. Opponents are trying to persuade the state to reject the permit application, which they see as the last opportunity to stop the project.

Local zoning rules do not apply to rail projects, and the Federal Railroad Administration has already approved the facility.

The decision to hold a public hearing, rather than a less-formal public meeting, is unusual. Since the law that governs storm water permits went into effect in 1997, no storm water permit application has ever before been sent to a public hearing.

Laura Welles, a staff attorney for the Department of Environmental Protection, will serve as the hearing officer.

No time has been set for the hearing. However, the hearing is expected to last all day and into the evening, according to Karl Wilkins, a spokesman for the department.