By Jeff Montgomery

The News Journal

A private engineer singled out by Gov. Jack Markell for praise after reporting tilting piers on I-495 said Thursday that he notified a DelDOT official about the problem late last week, and was surprised the state waited days before following up and closing the span for repairs.

Duffield Associates Vice President R. David Charles said he recalled thinking he had seen an optical illusion on May 29 when he noticed an out-of-kilter section of I-495 after parking nearby for a meeting.

A senior geotechnical engineer and principal with Duffield, Charles and a colleague investigated further and spotted trouble almost immediately. That trouble included large piles of earth close enough to bridge supports to raise worry that the heavy load would distort ground around crucial bridge structures.

"We went back to the fill pile that was over there and looked at the columns a little bit more and looked at them from a couple of different angles and came to the conclusion that at least one of them, and possibly two, might have been out of plumb," said Charles, who's expertise includes behaviors of soil and the engineering of structures in soils.

The two men snapped cellphone pictures and later enlarged them after returning to their office, then asked another Duffield employee to reach out to a DelDOT contact. Before the night ended last Thursday, emails and photos were relayed to state officials.

Anxious days followed.

"We were not sure what was going on. We did verify that DelDOT received the information," Charles said. "They did on Thursday night. Where it went from there, I'm not sure. I think the person we contacted at DelDOT thought that somebody else would take a look."

State officials shut the road down four days later, on Monday evening.

By Tuesday, Charles said, he saw that tipping and distortion of the bridge had increased significantly. "It was markedly more severe. It was very much more pronounced."

DelDOT Chief Engineer Robert McCleary confirms that the agency's bridge section received a call and emails from Duffield about the bridge on May 29.

"That was late in the day on Thursday, so Friday was the time that folks would have known about it at a staff level," McCleary said. "I wouldn't call it a routine call, but it wasn't a 'sound-the-alarm call.' It was, 'There's something going on with the bridge.'"

Transportation Secretary Shailen Bhatt said conditions at the bridge changed between the May 29 report by Duffield, and Monday, when engineers recommended closing the span. Geotechnical experts suspect that significant movement occurred over the weekend.

"If [the email] had said on Thursday, 'Your bridge is tilting to the right,' we would have dropped everything and gotten out here. That's not what it said. It said it was 'a little out of plumb,'" Bhatt said.

Earlier this week, Bhatt said the report of an anomaly came in late on May 30. An inspection crew went to the bridge Monday morning.

Bhatt referred to May 30 because that's when Barry Benton, assistant director of bridges, first learned of the Duffield report, Bhatt explained.

"We do not have anything to hide on this," Bhatt said.

"This is a major subterranean movement of earth. So whether we had come out and inspected it on Friday or Monday, the bottom line is that on Monday we would have closed the bridge. It's not something we do lightly. We have been methodical and thoughtful, with an eye on safety the whole time. And that's what we're going to continue to do."

Charles noted that Duffield "does a lot of work in soft soils" of the type around the span.

"We're aware that when you put embankments [piles of earth] over soft soils, you get a lot of settlement directly over the piles and a lot of movement at the edges," Charles said. "Seeing the fill piles next to the bridge and what looked like it could have been lateral movement, we thought there might be an issue there."

Markell, in an interview, said the state owes "a debt of gratitude" to the engineer who saw something awry and took immediate action.

"He was highly observant that something didn't look quite right," Markell said. "Thank goodness he, with his skills and his knowledge and his powers of observation, were there. Based on what I know, we certainly owe him a debt of gratitude."

Transportation officials expect the bridge will be closed for weeks until the structure can be leveled. Officials estimate that the affected section of interstate carries an average of 90,000 vehicles daily.

Melissa Nann Burke and Jonathan Starkey contributed to this story.

Contact Jeff Montgomery at 463-3344 or jmontgomery@delawareonline.com.