Wrong tunnel-digging equipment used in Kenilworth corridor

First-day error briefly caused excess vibrations, rattling homes

The hydraulic, press-in piler being used to construct the SWLRT tunnel in the Kenilworth Corridor, near Park Siding Park in Cedar-Isles-Dean. Construction crews used the wrong piling equipment on the first day of tunnel construction, leading to excessive vibrations for residents in the Cedar Lake Shores townhome development. Photo by Andrew Hazzard

Updated Nov. 21, 3 p.m.

The construction of the light rail tunnel in the Kenilworth corridor got off to a shaky start when crews working near Park Siding Park in Cedar-Isles-Dean used a prohibited piece of equipment for a few minutes on Nov. 15, causing robust vibrations and angering residents.

The half-mile tunnel, considered to be the most technical aspect of the Southwest Light Rail Transit project, was supposed to be dug using a hydraulic, press-in piler designed to reduce vibrations. But on the first day of tunnel construction, crews began that tunnel work using a vibratory hammer, which is prohibited in the Kenilworth Corridor by the project’s contract, according to Sophia Ginis, manager of public involvement for Metro Transit.

That equipment caused the ground to shake hard enough to trigger the project’s vibration threshold in the Kenilworth Corridor, Ginis said. Work has resumed using the hydraulic press-in piler.

Matthew Dahlquist, who lives in the Cedar Lake Shores Townhomes adjacent to the Kenilworth corridor, said his home began shaking violently in the middle of the day on Nov. 15. The shaking went on for about 30 seconds. He said he heard a loud cracking sound and believes a kitchen cabinet shifted.

The vibration paused and started again for five half-minute-long bursts, he said. Video from his house shows glasses on shelves shaking and clinking together.

For Dahlquist, an error on the most litigated and discussed work along the 14.5-mile project does not inspire confidence that the construction won’t negatively impact his home moving forward.

“This is one thing you should get right and they didn’t get it right,” Dahlquist said.

Council Member Lisa Goodman (Ward 7) received many calls from constituents fearing damage to their homes. She called the incident alarming and said it makes her question whether the Met Council is conducting proper oversight of their contractors for the project.

“Any oversight would be helpful at this point,” Goodman said.

Ginis said the error happened on the first day of tunnel construction, and that the vibratory hammer is being used on other sections of the project, though it is prohibited in the Kenilworth corridor.

For Goodman, contractors bringing the vibratory hammer to an area where it’s banned demonstrates problems with the way the project is being managed.

“It’s not like picking up an apple when you’re trying to grab an orange,” she said.

The vibration monitors the Met Council is using for the project can be falsely tipped off by as much as someone walking close to a monitor, Ginis said. Once excessive vibration is detected, Met Council staff are notified and immediately investigate the cause. If the excesses stem from construction, as in this case, work stops immediately.

The Met Council has been in contact with the Cedar Lake Shores Townhomes and the Calhoun-Isles Condo Association regarding the incident, she said.