A proposed concrete wall separating freight and light-rail trains along a short stretch of the Southwest light-rail line will “adversely affect” a historic rail district in Minneapolis, the Federal Transit Administration (FTA) said this week.

The 1.4-mile wall, which will be 10-feet high in some places, was added to the project at the behest of BNSF Railway, which owns the right of way between the Royalston Avenue/Farmers Market and Bryn Mawr LRT stations.

The $20 million wall would be located within the St. Paul, Minneapolis & Manitoba Railroad/Great Northern Railway Historic District. Because the Minnesota Department of Transportation (MnDOT) determined the historic district is eligible for listing on the National Register of Historic Places, a review of the proposed changes was required.

The FTA found the wall would “adversely affect” the historic district because building it would involve widening “the historic cut, removal of several historic retaining walls, replacement of historic stone and concrete walls and earthen embankment, changing its character.”

The wall will also serve as a “physical and visual barrier” between freight track and the historic rail yards, the review stated.

Now the Met Council, which is building and operating the $1.9 billion Southwest line, will work with MnDOT to prepare a “mitigation plan” to minimize the concrete wall’s effects on the historic property.

The Minnesota Historic Preservation Office, the city of Minneapolis and its park board, and Hennepin County are expected to contribute to the plan and offer suggestions on its design.

An open house for the community is scheduled for 5 p.m. to 7 p.m. Nov. 15 at the Bryn Mawr Elementary School, 252 Upton Av. S. in Minneapolis.

The 14½-mile Southwest light-rail line would connect downtown Minneapolis with Eden Prairie, with passenger service beginning in 2022.

Janet Moore • 612-673-7752 Twitter: @MooreStrib