Update: A Metro Green Line Extension impediment?

A buried “impediment,” detected by Kenilworth Tunnel construction workers in Minneapolis, has turned out to be a large slab of concrete. As part of its ongoing coverage of the Metro Green Line project, the Star Tribune reported on Thursday, March 3, that the slab had been removed earlier the same day.

Project spokesperson Trevor Roy explained in an email to EPLN on Monday that “It remains too early to say what impact if any the removal [of the slab]will have on tunnel construction.”

The cut-and-cover light rail tunnel site, a bit north of the Lake Street bridge near Bde Maka Ska, has been a contentious issue with neighboring residents and their state legislators. The expensive tunnel has been a story feed bag of extra costs and delays for regional news media.

Back on Feb. 1, Project Director Jim Alexander told the project’s Corridor Management Committee about what he would only describe as a “impediment” in the Kenilworth that might cause another delay.

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He did say that the impediment was buried in soil where the last of the project’s secant wall sections would be completed. Extreme cold weather had delayed an engineering assessment of the “impediment,” but Alexander assured the committee that an assessment would happen as soon as weather permitted.

Along with heavy snowfalls, the rest of February delivered warmer temperatures. It became tolerable. Project investigators excavated and identified the mystery impediment as a concrete slab. Because the concrete slab was buried next to the side of the towering Cedar Isles Condominium complex less than three feet from the tunnel’s secant wall placement, a plan was needed.

On this project, the secant walls will form a sealed tunnel inside which two light rail train tubes will be built. The secant sections are overlapping, interlocking concrete piles reinforced with steel beams. The unanticipated need for secant walls became apparent after the start of the project’s construction when soil and water problems were encountered in the Kenilworth Corridor. The Met Council approved the cost of the $30 million change order for the secant walls in September 2021.

Here’s how it worked out. Lunda/McCrossan JV construction crews with powerful concrete saws needed less than six hours to slice up and remove a mostly 14-inch thick, 20-square foot triangular section of the slab. The rest of it, apparently, remains underground.

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Eden Prairie Local News readers may wonder what relevance a buried concrete slab in Minneapolis has to with life in Eden Prairie. Two weeks ago, the mystery impediment and its potential impact on the Metro Green Line Extension project crested for a few days on the regional news cycle. As the new line will serve five cities including Eden Prairie, its impact extends beyond Minneapolis.

Editor’s note: Writer Jeff Strate served on the SWLRT Community Advisory Committee as an at-large member from February 2015 through February 2017. Jeff is also a founding member of the EPLN Board.

Cedar Isles Condos before LRT

A highly praised, silos-to-condos conversion, the Cedar Isles complex made its debut in the early 1980s as Calhoun Isles Condominiums. Concrete Magazine has archived a 1983 article describing the major makeover. “Old silos transformed into luxurious homes” can be read via this link.

The complex has roots in an expanding cluster of grain silos that emerged during World War I, when Minneapolis was the world’s leading flour milling city. Minneapolis milled-flour helped keep the Allies in Europe fed. By the 1930s and 40s, the grain elevators were served by railroads with scores of track spurs packed with trains filled with wheat and corn.

These days only the Twin Cities and Western Railroad (TCWR) carries freight through the narrow Kenilworth Corridor which it now shares with Metro Green Line Extension construction machines and work crews. Its trains move through the narrow Kenilworth stretch very slowly. Heading west, TCWR trains pass through St. Louis Park, Hopkins, Minnetonka and Eden Prairie.

Folks living on Leslie Lane, Alpine Way, Hunters Run, Evener Way Paulson Drive and Liv Lane have something in common with the residents of Cedar Isles Condominiums — Minnesota’s largest shortline railroad.