Crews working to reopen the collapsed eastbound lanes of U.S. 36 in Westminster shifted into rebuilding mode Wednesday as the Colorado Department of Transportation announced new details about the project.
CDOT for the first time identified a target of reopening the full highway by October. That depends on weather cooperating during the expedited effort by contractor Kraemer North America to rebuild the embankment, retaining wall and highway pavement, CDOT said in a project update Wednesday evening.
Until then, that section of U.S. 36 will continue to have two lanes in each direction sharing space on the westbound side, which CDOT says remains stable. An investigation continues into the collapse.
Growing cracks in the pavement resulted in the closure of the eastbound lanes between Church Ranch and Wadsworth boulevards on July 12. Eventually, a 200-foot section collapsed, and CDOT attributed the problem to a “slope failure” in which wet clay in the soil caused it to shift down the long embankment. The retaining wall also buckled over the course of two weeks before the soil finished settling.
CDOT and Kraemer crews worked to dismantle and remove the pavement and the retaining wall over the last few weeks, finishing that work Tuesday, according to the project update.
“We are pleased to begin the rebuild phase of this section of eastbound U.S. 36, and we look forward to getting traffic along this stretch back to normal as soon as possible,” CDOT Chief Engineer Joshua Laipply said in the news release.
The design chosen for the rebuilt eastbound section will use different materials than were used when the highway was rebuilt earlier this decade.
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Instead of backfill dirt behind the new retaining wall, Kraemer will place large geofoam blocks. The project also will include the drilling of caissons down into bedrock.
“Geofoam is a lightweight backfill that has been used effectively in similar situations with settlement,” CDOT’s release says. “Since geofoam is lightweight, it reduces pressure and stress to the underlying soil. It is also very strong, which means it can safely support highway loading and also lead to improved slope stability. Of the different options considered, this provides the best factor of safety.”