The Metropolitan Washington Airports Authority said on Monday that it will be making changes to the Silver Line’s Phase II in order to comply with new Virginia stormwater regulations.
This could add time and money to the $2.9 billion project, which is slated to be completed in 2018.

Phase II will run from Reston’s Wiehle Avenue to Dulles International Airport and into Loudoun County. MWAA is overseeing construction of the 11-mile extension, just as it did with Phase I, which opened in late July.

The stormwater runoff regulations are designed to protect the Chesapeake Bay watershed, said MWAA spokesman Marcia McAllister. The regulations by the Virginia Department of Environmental Quality took effect July 1 in order to better meet Clean Water Act standards.

“The old regulations required that the project only control the flow of stormwater,” she told WMAU.com. The new regulations require that pollutants not be discharged into tributaries to the bay, such as streams.”

The Silver Line’s second phase is being paid for with a combination of federal transportation loans, contributions from Loudoun and Fairfax counties and toll revenues from the Dulles Toll Road.

Since MWAA is making the change, MWAA will have to pay for it. The agency will likely dip into its contingency fund to do so. It is not known yet how much the changes will cost.