U.S. 36: CDOT will start search for answers, and blame, on 5-year-old section that’s crumbling

Four days after Colorado transportation officials closed part of U.S. 36 between Denver and Boulder, they are only beginning to turn to the mystery of how a five-year-old road could fall apart in such dramatic fashion.

While the Colorado Department of Transportation has pointed to water-saturated clay in the soil as the culprit, causing the ground to shift beneath the roadway, that’s only the immediate cause.

With a bypass of the eastbound lanes opened on Tuesday, CDOT in coming days will begin the work of assessing blame for the situation — and deciding whether the mess could have been prevented.

The determination could affect whether the state must eat the costs for the emergency repairs or can pass them on to contractors that either built the expansion project or are charged with maintaining the roadway in a public-private arrangement.

It’s possible the section of freeway near Church Ranch Boulevard fell victim to unforeseen conditions, such as a particularly wet series of storms over the course of several months, or that inspectors missed warning signs.

RELATED: Two eastbound lanes of U.S. 36 opened for Tuesday rush hour

But a construction expert raised questions Monday about the construction and design of the first phase of a roughly $500 million expansion of the highway.

Bruce Finley, The Denver Post

Workers survey a large crack along eastbound U.S. 36 between Wadsworth and Church Ranch boulevards on July 14, 2019.

“I would like to see the tests that were done” on the soil before construction, said Cristina Torres-Machi, an assistant professor of construction engineering management at the University of Colorado Boulder. “What were the technical studies done for that segment of the highway? How many samples were taken?”

And, just as important: How did the project’s design and construction address those challenges?

Problem soils aren’t new for the northwest metro area, and that part of 36 is close to a marshy area.

Advertisement

Scroll to continue reading

Not far away, expanding soils containing clay began posing a problem more than a decade ago for some buildings at the FlatIron Crossing mall. Burrito chain Chipotle left over safety concerns, and other businesses reported structural problems after wet soils swelled beneath their foundations.

A complication for CDOT’s coming inquiry is the complexity of the project’s contracting. While some observers are pointing fingers at a 50-year public-private partnership agreement struck with the contracting consortium Plenary Roads Denver, that outfit didn’t actually oversee the building of the section at issue — but it is charged with maintaining it.

Given the soil-shifting problem, which a CDOT engineer referred to as a “slope failure,” Torres-Machi said it wasn’t surprising that it took several years for concrete to begin buckling in the roadway and a 45-foot-tall bridge approach structure below it.

“You shouldn’t expect this to happen right after construction, but some years after construction,” she said.

CDOT deferred questions about the project’s contracts and how it will handle the issue for later, after the immediate crisis — the closure of the eastbound lanes — had passed. That direction was closed from Wadsworth to Church Ranch from Friday through Tuesday morning, when the temporary eastbound bypass lanes opened on the westbound side.

“While this incident is ongoing, CDOT remains focused on the safety of the traveling public and staff on the scene,” spokesperson Matt Inzeo said in a statement, adding: “Once operations are stabilized, we will explore the relationship between project partners.”

Joe Amon, The Denver Post

Significant damage on U.S. 36 caused by sub-structure and settlement issues is visible in Westminster on July 15, 2019.

Project had contracts for 2 phases

Those relationships are more complex than usual, due to the way the project was built.

U.S. 36 was expanded, with express lanes added, in two phases. The section where the emergency shutdown occurred was part of the first phase, which was built by a joint venture led by Granite Construction and Ames Construction in a design-build contract, a typical arrangement for a public project.

The second phase of the project was more unusual. Plenary Roads Denver won a 50-year public-private partnership agreement that began with construction work on the highway starting at 88th Street in Boulder County and going northwest. Granite and Ames joined that team, too, as the construction partners for the later phase.

After the second phase’s completion, Plenary Roads took responsibility for operating the toll lanes and maintaining the entire roadway — including the Phase 1 portion — for decades to come.

So the upshot is that Granite and Ames built the now-buckling section of the project under the first contract, while Plenary Roads’ other partners — including Ferrovial Services — are responsible now for maintaining that section under the second contract.

In a statement, Plenary Roads Denver said it was coordinating with CDOT and the department’s High Performance Transportation Enterprise, which oversees the partnership agreement, “to assess what happened on this specific section of roadway” and to make repairs.

Reached Monday, an executive with Ames Construction’s office in Aurora declined to comment, while an attempt to reach Granite Construction, based in Watsonville, California, was not successful.

Plenary Roads’ ongoing contract allows for claims to be filed when unforeseen issues arise, and in this case that could mean a claim for CDOT to reimburse it for lost toll revenue. But Torres-Machi said its maintenance responsibilities didn’t seem likely to be at fault.

“I wouldn’t think that would be something you could fix with maintenance,” she said. “I think it’s more a design problem that those collapsible soils were maybe not identified in that segment of the highway. Usually you would stabilize them before building the highway so that they’re not sensitive to water. So I would lean to a design problem.”

Kate Williams