Near Disaster in Delaware: Span Dwindles on Unsteady Soil

Mon June 16, 2014 - Northeast Edition
Randall Chase - Associated Press


(AP Photo/Patrick Semansky)
Workers remove a pile of dirt next to the Interstate 495 bridge over the Christina River near Wilmington, Del.,  June 5. The bridge was closed after the discovery of tilting support columns, and officials suspect that the dirt
(AP Photo/Patrick Semansky) Workers remove a pile of dirt next to the Interstate 495 bridge over the Christina River near Wilmington, Del., June 5. The bridge was closed after the discovery of tilting support columns, and officials suspect that the dirt

WILMINGTON, Del. (AP) The removal of a massive mound of dirt suspected of causing a nearby interstate bridge in Delaware to tilt is almost complete.

Officials have said removing the dirt is the first step in getting the bridge repaired and reopened to traffic, a process expected to take weeks, if not months.

Two backhoes continued to claw away June 8 at the dirt mound beside the bridge, which normally carries about 90,000 vehicles a day on the Interstate 495 bypass around Wilmington.

James Thomas Jr., a contractor who dumped the mountain of dirt, which officials estimate at a weight of 50,000 tons, (That’s equal to about 1,250 18-wheel tractor-trailers at the maximum gross vehicle weight of 80,000 lbs.) has been working with the state to remove it.

Thomas’s father, who founded the materials handling company that allowed his son to store the dirt on property it leased, said his son makes sure the soil is not polluted.

"People do excavations and can’t get rid of the dirt, and they bring it to Jimmy," the elder Thomas said. "If it’s dirty, he won’t take it. It’s got to be clean."

State officials are trying to determine whether any permits were required to store the dirt next to the bridge. Globetti said stormwater and sediment regulations require permits for ground-disturbing activity of 5,000 sq. ft. or greater.

State transportation secretary Shailen Bhatt said his agency did not know of the dirt mound until June 2, when engineers visited the bridge in response to a report received a week earlier of a possible problem. That report came from an engineer with a private company who was in the area on an unrelated project and saw cracking in the soil around the dirt pile on the east side of the bridge — the direction in which the four pairs of columns are tilting. The engineer then spotted the leaning columns and contacted DelDOT.

A 911 Call

A Delaware businessman said he told state transportation officials nearly two months ago something was wrong with a major highway bridge, raising further questions about why they waited until this just recently to inspect the span and close it after discovering tilting supporting columns.

Charles Allen Jr. told The Associated Press on June 6 he noticed that the cement Jersey barriers dividing the northbound and southbound lanes of the Interstate 495 bridge in Wilmington were separating when driving over the bridge on April 15.

"I’ve been driving that road for 34 years," said Allen, owner of an automotive body shop in Wilmington who lives in Elkton, Md. "When you see something off, it catches your eye."

Allen said he called 911 after not being able to reach the transportation department immediately. He said a transportation official called him back minutes later and told him someone would look at the bridge the following day. He said that was the last he heard from the department before he started making calls again after the bridge was closed June 2.

"I was ditched by these guys," Allen said. "They didn’t do their job and they really aggravated me ... That’s what makes me so mad."

Allen spoke to the AP after The News Journal of Wilmington published an interview with him on its Web site June 6. The newspaper also posted a recording of the 911 call.

Transportation secretary Shailen Bhatt told the AP his department is "running down details" on Allen’s story.

Kelly Bachman, a spokesman of Gov. Jack Markell, said the governor "has full confidence in Secretary Bhatt." She said the state’s focus was on finding a way to fix the bridge, and once that’s done, officials will fully evaluate the agency’s response."

Bhatt said an engineer working on an unrelated project near the bridge first reported problems with the bridge May 29. Bhatt said senior managers in his agency became aware the next day and ordered an inspection June 2. The bridge was closed immediately.

"We closed the bridge in time," he said. "We did not have a failure. That bridge is still standing and nobody has been injured. I’m happy to accept responsibility for this agency’s actions."

Still, Bhatt said he would have preferred his agency to have moved more quickly to inspect and shut down the bridge.

The federal government has pledged to pay 90 percent of the cost of permanent repairs and has already approved $2 million in emergency funds. The cost of fixing the bridge hasn’t been determined.

Officials also said Friday that tilt sensors placed on the bridge have shown no additional significant movement.

Engineers have completed inspections of all eight affected columns and found cracking consistent with the lateral displacement of soil, in all the concrete footers. No corrosion was found in the tops of the underground steel piles anchored to the footers.

Agency consultants are reviewing design options to create a new foundation for the damaged section of the bridge, officials said.

Dave Charles, the geotechnical engineer who reported the problem said he returned to the bridge on June 3 and saw that the columns had shifted even farther.

Charles said after he and a colleague working on an unrelated project near the bridge noticed May 29 that it appeared to be tilting, he sent matter-of-fact emails with cellphone photographs about 6 p.m. that day to an employee of the Delaware transportation department’s bridge unit. Charles said the employee, whom he declined to name, acknowledged about 90 minutes later that he had received the emails.

"I think the person who received it took it seriously," Charles said.

In his April 911 call, Allen is heard telling a dispatcher, "It appears to be an emergency. ... The two road beds are lifting up opposing each other, and it doesn’t look right. Something’s wrong ... There may be something seriously wrong with that bridge."

Repairing the Bridge

The southbound lanes of the I-495 bridge spanning the Christina River in Wilmington, Del., could be open as soon as Labor Day this year, and the northbound lanes would be opened several weeks after that, announced DelDOT Secretary Bhatt on June 10.

"The timeline that we are announcing today is only possible because we have acted quickly to mobilize firms and personnel that have a proven track record of reopening critical transportation infrastructure under deadline pressure," Bhatt said. "As of today, the people, materials and equipment needed to reopen the I-495 bridge is on its way to Delaware from across the United States."

Design for the project is being managed by AECOM . Construction will be performed by J.D. Eckman Inc. The two firms have a history of successful collaboration of rapidly reopening other bridges on the U.S. interstate highway system, including structures on I-95 in Philadelphia and Wilmington.

The plan to reopen the bridge to traffic calls for the construction of new concrete-filled shafts down to bedrock beneath the columns that have tilted out of alignment. These shafts will create a stable surface above the underlying unstable soil. The concrete shafts will be tied together with a reinforced concrete grade beam. Temporary jacking towers would be erected on the grade beam to restore the bridge’s superstructure to its original position, and lift the weight off of the existing, rotated piers. Once the bridge has been rendered safe for traffic, permanent new concrete columns will be erected taking the place of the jacking towers.

The first phase of construction to reopen the bridge is estimated to cost $20 million, while the cost of the permanently fixing the problem is not yet certain, said Bhatt said.

There were a number of options considered for reopening the bridge, Bhatt said.

"We first looked at just shoring up the existing bridge, but that option was quickly ruled out because of the poor soil conditions. Another idea was to fully reconstruct this section of the bridge. That option would’ve put us at an early 2015 opening, which was not a viable option given the traffic volume the bridge normally carries."

Bhatt said it became immediately clear that the most expeditious way to make the repairs was to bring in the contractor early, so that from day one the firm that will fix the bridge is working side-by-side with firm who designed the structure. "We didn’t want to lose time by designing something on paper that a contractor couldn’t build in the field. Work will proceed 24 hours a day, seven days a week until the bridge is reopened," he said.

Regarding potential causes and when the problem was first detected, Bhatt said, "A lot of the questions we’re receiving right now are about what caused the bridge to tilt, whether it should’ve been closed sooner, and when did DelDOT know about the tilt. I want to be clear that we will do a thorough analysis of agency actions and the causes that led to this situation. We will do so in a transparent manner by sharing our findings publically. However, the major focus of our efforts as an agency right now is to get this bridge reopened as safely and quickly as possible."

(Associated Press Writer Ben Nuckols in Washington ands DelDOT contributed to this report.)