Shaking Things Up

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by Charles Collier, The Denmark News

DENMARK – Altered travel habits, complications with summertime events, and general construction season blues are sure to cause rumblings while N. Wall St. is reconfigured this year. An addition to the project’s list of requirements by the Village Board on Monday, March 5, will limit some of the more literal vibrations.

On the recommendation of the Village’s engineer Mick Magalski, the Board approved adding pre-construction surveys of the properties along the road and seismography equipment during the complete overhaul of underground utilities in response to resident complaints during last year’s Pine St. construction.

“The deep vibratory compaction is essential to ensure proper consolidation of materials,” which protects against a variety of potential issues, Magalski said in the meeting.

The south end of N. Wall has storm sewer lines just as deep as those on Pine, and the same intense vibration will be required before the rest of the project can safely move forward.

“It’s very important and can’t be avoided,” Magalski said, “That’s one of the natures of deeper sewer.”

Some contend that such necessities of construction can have unintended consequences, like cracked plaster or concrete in and around a home. Often times, though, the causal link is hard for homeowners to demonstrate in court without multilateral documentation.

“It’s very difficult to say in those conditions whether it was caused or whether it was existing,” Magalski said.

In at least one instance, the Village helped repair concrete steps which were reported to have cracked during construction.

With the additional pieces the first step of construction will be photographic surveys of potentially affected properties, showing where damage does or does not exist before crews start construction. Participation in this preliminary measure is voluntary.

As work continues, at least one trained operator would be monitoring vibration levels—some sites feature multiple operators walking from spot to spot. The Wisconsin Dept. of Transportation (DOT) limits vibration for underground utility work to a Peak Particle Velocity (PPV) of two inches per-second.

Should the threshold be exceeded, all work would be required to cease and affected properties inspected for damage; a Peak Particle Velocity (PPV) of two inches per-second. DOT notes that some of construction’s heaviest equipment ranges between .64 PPV and 1.51 PPV while on the job.

“It takes a lot to hit that threshold with normal compaction, even with these deep sewers…it’s not like the contractor is going to hold back because they know they still have to meet the required density,” Magalski said, adding that just twice in 25 years of experience has he seen vibration limitations broken.

“One was a result of a truck, actually, hitting a power pole right next to the seismograph. The other was not construction-related at all, so it’s very difficult with normal compaction to exceed those [limitations],” Magalski said.

At the end of the project, properties will again be voluntarily surveyed for damage with claims being matched against the data before the process of remediation begins.

Design plans for N. Wall approved by the Village in December are still under review by Urban Development, a USDA grant program, but Magalski said he anticipates starting construction in May, consistent with the original time frame.

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