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Tests: Silver Line concrete problem may not be as bad as feared

The Metropolitan Washington Airports Authority meets on July 18. (WTOP/Max Smith)

ARLINGTON, Va. — Initial tests on faulty concrete panels triggered by a whistleblower lawsuit suggest a widespread reworking of the Silver Line extension to and beyond Dulles Airport may not be necessary.

The lawsuit had raised concerns that use of incorrect stone, in addition to separately discovered improperly mixed concrete, at Silver Line stations scheduled to open in 2020 could lead to premature breakdown of the concrete panels.

The Metropolitan Washington Airports Authority has taken core samples from 20 of the panels, and the first half or so of those results have found no significant issues, Charles Stark, MWAA vice president for the Dulles Corridor Metrorail Project, said Wednesday.

“Early indications are very favorable at this point,” Stark told the Airports Authority Board Wednesday morning. “No reaction has been found in any of the cores that have been taken — so far.”

Two separate labs are reviewing the samples — one for the Airports Authority and one for the private contractor constructing of the rail line.

“What we’ve seen so far is there’s no evidence of micro cracking or a reaction taking place,” Stark said.

Any reaction would be driven in part by water getting into the panels, which the construction contractor plans to prevent by providing for protective coatings every 10 years. That was planned in response to the separate problem of improperly mixed concrete, but will also address any potential problems with the chemical makeup of the stones used in the panels.

“We’re fairly certain that, unless we see something untoward in the remaining laboratory examinations, keeping water out of the concrete will preclude any problem going forward,” Stark said.

Comprehensive final test results on the stone are expected within three weeks. Certain material certifications must also be completed for the panels, which essentially serve as some station walls.

Metro is separately reviewing the results and testing that is underway to ensure the rail line is durable when the transit agency takes ownership of it from the airports authority sometime next year.

The extension from Wiehle-Reston East to Dulles Airport and Loudoun County is still expected to start carrying riders in early 2020, Stark said, and the concrete issues are not expected to delay that.

Test trains could begin running on part of the tracks as soon as October.


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