Administrator: Despite Leaks, Big Dig Tunnels 'Safe'

State Transportation Department officials may have re-written an internal report in order to downplay the corrosive effects of water leaking into Big Dig tunnels, according to documents obtained by The Boston Globe.

The initial report did not say the tunnels are unsafe, but did say constant water leaks have corroded electrical systems, flooded air vents and are damaging steel girders that support the Tip O’Neill Tunnel.

In a memo to the state Board of Transportation, state Highway Administrator Frank DePaola disagreed with the lead engineer's report and implied that the leak problem is being effectively contained.

"What I said in my report to the board is that we're managing the leaks," DePaola told Morning Edition's Bob Oakes. "Water continues to leak into the tunnels. Because of the size and magnitude of the Central Artery tunnel system, the total amount of water seems large, but in reality, on a daily basis the amount of water coming into the tunnel is relatively small."

Fixing the damage could cost tens of millions of dollars.

"Corrosion of structural steel items is not a new condition for the Highway Division of the Massachusetts Department of Transportation," DePaola said. "All of our facilities — our roads, our bridges, our components, our signposts — all over the state we deal with exposure of pieces to the elements. We have to deal with corrosion as part of our daily maintenance."

Despite the corrosion, DePaola assured commuters that "the tunnels are safe."

"The design of these structures is for a 75-to-100-year life," DePaola said. "What we need to do to make sure that we get that lifetime out of those structures is that we constantly work on maintaining them."