Behind the unwatering operation at NYC's Brooklyn Battery Tunnel

(CBS News) Superstorm Sandy brought 60 million gallons of water rushing in to the historic Brooklyn Battery Tunnel at the southern tip of Manhattan. The storm's surge flooded nearly two miles of the the Brooklyn Battery, the longest continuous underwater tunnel in North America.

Typically 45,000 vehicles pass through the tunnel daily, but since last Monday, the tunnel has been out of commission and flooded with water.

CBS News' Jeff Glor joined the Coast Guard, Army Core of Engineers, and New York Transit Workers as they fought through another storm -- this week's Nor'easter -- to fix the tunnel.

Ronald Pinzon of the Army Corps of Engineers told Glor, "This latest storm doesn't make it any easier, no it doesn't. What that could do is bring more water to the area and the high winds are a concern."

This week, water was still rushing out of the tunnel, getting pumped from deep underground, as the team set about fixing it.

Romolo De Santis, the facility engineer at the site, told Glor that the biggest challenges of trying to pump out water from seven stories underground is dealing with factors like "the pressure loss, access, ventilation issues" and "electrical power we're trying to restore."

Each of the tubes used in the unwatering operation can clear 2,000 gallons a minute and are powered by pumps using four diesel generators. As of Thursday, the water has been pumped out from the west tube of the tunnel and the water that remains is under the tunnel or directly above it.

When the water is gone, the crew faces mounds of mud, sand, and garbage that needs to be cleared and an electrical system that has yet to dry out. 

 De Santis stopped short of putting an estimate of when the roadway will repopen but looking to the future, he said,  "We have to start looking at ways to hopefully prevent it again from happening...sea walls, barriers, gates at the tunnel."