U.S. 36 collapse report cites drainage design, heavy rainfall during construction as possible culprits

Water-saturated clay in embankment shifted beneath a retaining wall, causing 2019 incident
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Posted at 9:51 PM, Aug 12, 2021

DENVER -- Design flaws in a retaining wall drainage system and heavy rains during construction may have contributed to a “slope failure” that caused the collapse of U.S. 36 in Westminster two years ago, according to an outside engineering report released Thursday by the state.

The forensic investigation report‘s release comes less than a week after the disclosure of a$14 million settlement reached by the Colorado Department of Transportation with a group of construction and design contractors. They had rebuilt and expanded the highway just five years before the eastbound side collapsed in July 2019 near Church Ranch Boulevard.

The settlement covered most of CDOT’s $17.6 million in response and repair costs.

The report by CTL Thompson, a Denver geotechnical engineering firm, was prepared for the Colorado Attorney General’s Office as considered taking legal action. The Denver Post filed a public records request to obtain it.

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