Minneapolis condo residents want vibration study before Southwest light rail goes forward

Two years ago, construction began on a new apartment building on West Lake Street in Minneapolis where the former Tryg's restaurant once stood, a little more than 150 feet from the Calhoun-Isles condominiums.

Vibrations from construction caused cracks in the walls of a condo tower in the bucolic complex off Dean Court, former grain elevators built during Minneapolis' milling heyday in the early 20th century, and retrofitted in the 1980s for residential use.

Calhoun-Isles residents began to wonder how their unusual homes with foot-wide concrete walls would fare when construction of the Southwest light-rail line begins later this year. The trains will run near the complex in a shallow tunnel, whose footings are just 2 feet away from one of the condo towers, and nine inches away from its parking garage.

Residents also worry about the noise and vibrations caused by the 200-or-so light-rail trains moving through the tunnel every day at 45 miles an hour, should the project be built.

"None of us knows what to expect," said Nick Shuraleff, a Calhoun-Isles resident and president of the condo board, in an interview last month. "We need an independent expert to do a study."

The condo board estimates that such a study would cost the $1.9 billion project an extra $50,000. But they say the Metropolitan Council, the builder of the Southwest project, has brushed aside their concerns.

The regional planning body claims that such a study would require an unnecessary and expensive overhaul of an environmental plan already approved by the Federal Transit Administration (FTA).

"The council is doing its due diligence to avoid, minimize and mitigate construction damage throughout the entire Southwest LRT corridor," said spokeswoman Kate Brickman.

Unsatisfied, the condo owners turned to Sen. Scott Dibble and Rep. Frank Hornstein, DFL legislators from Minneapolis who inserted a provision in the transportation budget bill during the legislative session that called for a vibration susceptibility study at Calhoun-Isles. Their initial request said the study would be conducted by a firm of the condo owners' choosing and paid for by the Met Council.

But Gov. Mark Dayton stripped out that provision — and 17 others — in the chaotic final moments of the session, claiming he found them troublesome.

Dibble and Hornstein then added new, albeit weaker, language to the bill that requires the Met Council to implement a plan to prevent vibrations from affecting the Calhoun-Isles property. This includes keeping vibrations at federally accepted levels, conducting pre- and post-construction inspections of the buildings, and establishing a "fair and objective" method to process damage claims, among other caveats. But further study is not included.

"It was my understanding the Met Council had objections" to the original language, Hornstein said. "At the very least, residents have a seat at the table" to voice their concerns during construction and operation of the Southwest line, he said.

Unlike other residents from the Kenwood area who have filed a lawsuit in federal court to block the Southwest line, the Calhoun-Isles condo board has remained neutral on the project. But after experiencing the construction-related damage in 2015, the board hired the Itasca Consulting Group, a Minneapolis-based engineering firm that operates worldwide, to conduct a preliminary study.

"We want to employ science so our residents are protected," explained Paul Petzschke, a retired 3M engineer who lives in a townhouse at the complex.

In a May 21 letter to Dayton, Shuraleff said the initial study conducted by the Itasca group "helped us understand the reasons why Calhoun-Isles is so sensitive to vibrations." Using vibration data from the West Lake Street apartment project, Itasca determined that the high-rises are especially sensitive to vibrations.

"The Calhoun-Isles experience is noteworthy because they were subject to damaging vibrations related to a project 150 to 170 feet away from them," said Lee Petersen, a principal engineer with the Itasca Consulting Group. "It's very unusual for vibrations from pile-driving to cause damages from those distances."

The vibration levels "were below what you would expect to cause damage," he said. "So that was kind of a warning flag." (Townhouses in the complex were damaged, as well.)

This is likely because the building itself is so unusual — the condo owners say they know of only one other grain elevator in the country that has been rehabbed into residential units. (It's in Massachusetts.)

So it's difficult to generalize how vibrations will affect the concrete, fortresslike structure. As Shuraleff puts it: The grain elevators behave "just like an iron bar. You hit it, and it keeps resonating."

The council disagrees with the findings, claiming the towers are in a lower building classification that is the least likely to experience vibration damage.

Brickman says the council has agreed to build a "tunnel slab" beneath trains in the Kenilworth corridor that will significantly reduce vibrations, and use rail fasteners in the tunnel that help dampen vibrations, too.

LRT-related vibration concerns are not new to the Met Council. They were cited by the University of Minnesota, KSTP and Minnesota Public Radio during construction of the Green Line. MPR filed suit in Ramsey County District Court against the Met Council over the issue, but the case was dismissed. A subsequent settlement resulted in the council paying MPR $3.5 million.

Ironically, the Itasca group was hired by the Council to help resolve Green Line vibration issues with the U.

Janet Moore • 612-673-7752