Unusual Soil Condition leads to possible road re-do in Oakdale

OAKDALE — No doctor wants their patient to become a medical textbook case, and no engineer wants their road project that becomes a case study, but that might have happened in Washington County.

What began as straightforward pavement improvement on 10th Street in Oakdale has turned into a project that engineers from outside firms are studying to see exactly what happened.

The project, a mill and overlay from the Interstate 694 bridge to 300 feet east of Inwood Avenue North, County State Aid Highway 13, required one layer of new pavement. But during the paving operation, sections of the roadway shifted unevenly, and now the new pavement is rougher than the previous surface.

County engineers believe this happened as a result of the heavy equipment used in the milling operation, coupled with the vibrations from the pavement rollers when the pavement was placed.  This road was originally built over a swamp/lake – and it appears the vibrations and weight may have “liquefied” the saturated sub-grade soils causing these uneven shifts.

Whatever the cause, the roadway shift was unexpected. There was nothing in the pre-condition survey indicating this could or would happen.

It has never happened in the county before, and soil specialists under contract to the county are performing additional soil drilling and investigation. Engineers from at least one firm have expressed interest in reviewing just what happened during the paving process to upset the land below the roadway.

The county’s goal now is to work with soil specialists to develop a plan to fix the road this year. This will very likely involve removing the new pavement, and possibly full depth excavation in some areas.

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