Silver Line extension to Dulles awaiting test results on concrete issue

HERNDON, Va. — The Silver Line extension project to Dulles International Airport is now waiting on test results that could determine whether it opens on time.

Project director Charles Stark told the Dulles Corridor Advisory Committee, a body made up of regional and transportation leaders, that three problems with concrete wall panels at five stations under construction had already been identified before news of a whistleblower lawsuit broke.

Stark said applying sealant to the concrete would resolve those three issues, but another issue had come to light along with the lawsuit in May.

That issue is a chemical reaction in the concrete, known as alkali-silica reaction, which can cause cracks and reduce the service life of concrete structures.

Others have dubbed it “concrete cancer.”

“When the complaint was unsealed, we found an additional allegation, which we had previously been unaware of,” Stark said.

Stark said the problem only affects the durability of the concrete panels at the stations.

“With regard to safety, the strength of the concrete has never been in question,” he said.

A lab will now be testing samples of the concrete to find out the extent of the problem and the results are expected back in seven to eight weeks.

The findings will determine whether the problem can also be fixed using the existing plan to apply a sealant, or if, in a worst-case scenario, the panels might have to be replaced.

“It’s on the table, if required,” said Metropolitan Washington Airports Authority CEO Jack Potter about replacing the panels. “We’re going to let the science drive our decisions.”

Replacing the panels could delay the opening of the Silver Line extension into Loudoun County, Virginia.

“A delay costs money, so hopefully that doesn’t happen,” said Loudoun County Board of Supervisors Chair Phyllis Randall. “Obviously, it is more important to get it right than to do it quickly.”

That sentiment was shared by Fairfax County Board of Supervisors Chairman Sharon Bulova.

“I am concerned that there could be a delay,” she said. “On the other hand, if a delay is required in order to ensure safety, that’s what needs to happen.”

The rail extension is being built by the airports authority and will be transferred over to Metro when completed. The hope has been for it to be open to riders by 2020.

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