All shook up

Neighbors say a construction project portends trouble for Southwest light rail

Paul Petzschke said the unique design of the Calhoun Isles Condos building seemed to amplify vibrations from nearby construction. Credit: Dylan Thomas
Paul Petzschke said the unique design of the Calhoun Isles Condos building seemed to amplify vibrations from nearby construction. Credit: Dylan Thomas

CEDAR-ISLES-DEAN — The floor-to-ceiling windows of John Wessinger’s condominium in the Loop Calhoun building look west, their view framing what has troubled him and many of his neighbors since early this summer.

A block or two distant from his condo building is the southern end of the Kenilworth Corridor, where construction of a tunnel for the Southwest Light Rail Transit project is expected to begin in 2017. If Wessinger and many of his neighbors look forward to that date with a sense of trepidation, it’s because of the scene that dominates the foreground of his view: a half-block-long construction pit crawling with machinery.

This spring, work on a new apartment building was halted for weeks at 3118 W. Lake St. — better known as the former Tryg’s restaurant site — when damage was reported at several nearby buildings, including the Loop and the Calhoun Isles Condos located just across the Midtown Greenway. During installation of sheet piling for the apartment’s foundation, vibrations rattled the dishes in Wessinger’s cabinets “like an earthquake” and left hairline fractures in his walls.

What neighbors experienced then was just a “prelude” to SWLRT tunnel construction, said Cedar-Isles-Dean Neighborhood Association (CIDNA) President Craig Westgate. Westgate contends Metropolitan Council, the agency leading the $1.77-billion transit project, has not adequately prepared to deal with what could be significant damage caused by the tunnel work.

“It’s not conjecture,” Wessinger added. “… We kind of went through this, and we kind of know.”

A 2014 SWLRT technical document outlined two potential methods for sheet pile installation during tunnel construction: “high frequency vibratory hammer or a hydraulic ‘press-in’.” Planners say they are leaning toward hydraulic press-in, a technique that relies on hydraulic rams instead of hammers, because it is expected to minimize vibrations.

But there’s skepticism at the south end of the Kenilworth Corridor, especially after a 2014 Met Council-led sewer project prompted damage claims from area homeowners. The corridor is one of the narrowest points on the entire 14.5-mile SWLRT route, and the tunnel will be dug within a few feet of the foundation for the Calhoun Isles Condos building.

City Council Member Lisa Goodman, who represents the area, said the “risk on the tunnel is extremely high.” At a September City Council meeting, Goodman referred to problems at the Tryg’s site before predicting Met Council would meet failure on the tunnel project.

“And in the end,” she said, “they’re not going to be able to build the tunnel because we know that there are all sorts of issues with the soils and these methods.”

“Vibrations like crazy”

After a summer of delays for developer Trammell Crow, foundation work at the Tryg’s site finally was completed this fall. Big-D Construction cycled through several

construction techniques before settling on what’s known as a drilled caisson system.

“You drill into the ground and place H-pilings, which is big beam, basically,” explained Chris Grzybowski, vice president and managing director at Big-D’s Minneapolis office.

This spring’s first attempt at the foundation involved vibrating sheet piling into place, a common and cost-effective approach. Grzybowski said Trammell Crow’s team “did a thorough job vetting” the plan, setting up seismic monitoring stations and investigating the pre-existing conditions in the area, but acknowledged “it’s an obtrusive process,” especially in a residential area.

“In my mind, these guys were extremely responsive,” Paul Petzschke, a member of the Calhoun Isles Condominium Association, or CICA, said. “Once they realized what kind of damage they were causing, they backed off right away.”

Petzschke said CICA invited representatives of Big-D and others involved in the apartment project to a meeting at the Calhoun Isles building this spring, and they all noticed something unusual. The vibrations seemed to feel stronger in the 10th-floor conference room than at ground level.

“The consensus was we had a vibration that could resonate as it climbed the tower,” Grzybowski said.

In Petzschke’s ground-level townhome, plaster cracked. In an acquaintance’s 10th-floor condo, the chandelier was swinging, he said.

Petzschke chalked it up to the unique design of the Calhoun Isles building, a former grain elevator that was converted to condominiums in the 1980s. Some walls are foot-thick concrete, he said.

“The concrete remains relatively stable, but it’s transmitting the vibrations like crazy,” he said.

As for the earth beneath the former Tryg’s site — another topic of much speculation — Grzybowski said “there’s nothing unusual about the soils,” describing them as “fantastic sand material.” His crew did, however, did have to drill through boulders encountered at what he described as “significant depth.”

Grzybowski said he didn’t have first-hand experience with the hydraulic press-in technique Met Council plans to use for tunnel construction, and made no predictions of what the agency will find in 2017.

As of mid-October, Met Council had not communicated directly with either the developer or the contractor about construction issues at the Tryg’s site. That changed after a reporter began making inquiries, but a Met Council spokesperson said the agency was still “playing phone tag” with Trammell Crow at the end of the month.

“A tremendous amount of distrust”

Paul Miller, a senior project manager in the Department of Public Works, said the hydraulic press-in technique is rarely used in Minneapolis, in part because vibratory sheet-piling is typically much easier and cheaper. Complaints from neighbors and reports of damage — including to public infrastructure — are not uncommon, either, Miller added.

He said Met Council’s plans for tunnel construction would be outlined in much greater detail when the agency files a construction mitigation plan, probably next year. Met Council’s pre-construction investigation of the tunnel site already has  “gone way, way beyond” what most builders do, Miller added.

“I would disagree with anyone who says the Met Council doesn’t have a good handle on this,” he said.

But years of wrangling over the route of SWLRT have soured many who live near the Kenilworth Corridor on the Met Council-led process. Then, last year, when several area homeowners claimed cracked stucco, damaged interior walls and fractured driveways from a Met Council sewer reconstruction project, they were initially told to settle their claims with a contractor. Only after Sen. Scott Dibble intervened did the agency bring in an independent adjustor and structural engineer to investigate.

“There’s a tremendous amount of distrust, and little things really get people going again,” Westgate, the CIDNA president, said.

Early this year, both CIDNA and the Kenwood Isles Area Association passed resolutions calling on Met Council to establish a process for resolving damage claims related to its projects. The resolutions referred to the sewer project, but clearly looked ahead to tunnel construction.

Goodman said she holds Miller in “high regard,” but doesn’t share his opinion Met Council’s trustworthiness.

“My concern is that, to be honest, they don’t really want to build a tunnel,” she said.

If the tunnel plan failed for one reason or another, Met Council could decide to run light rail trains at grade alongside an existing freight rail track. Under that scenario, the narrow Kenilworth Corridor might have to be widened, requiring the removal of nearby homes. But eliminating the tunnel would also violate an agreement between Met Council and Minneapolis and require the agency to once again seek approvals from all the cities along the SWLRT route.

It’s a hypothetical, but one that looms large for those living nearest the Kenilworth Corridor pinch-point.

“The biggest fear most people have in the corridor is it will be at-grade and they will start taking properties,” Westgate said.