Millions of gallons of water streamed into the World Trade Center site during Sandy, cascading through the PATH terminal and down ramps used for construction vehicles. But officials say the prognosis for flooding, and any other hurricane damage, should be much better once the 16-acre redevelopment is complete.

“We had a large scale presence of the Hudson River at the site,” said Larry Silverstein, the developer constructing some of the office buildings there. “Once you have an open construction site, there is no physical way to keep it all out.”

Silverstein estimates the east “bathtub” along Church Street took on about 15 to 20 feet of water. A government official, who spoke on condition of anonymity because he was not authorized to talk about the subject, said between 150-200 million gallons of water entered the lower level of the complex, which includes interconnected portions of 1 World Trade Center, the PATH terminal and the September 11th Memorial and Museum. (The PATH and Memorial are closed due to the storm.)

As of mid-day Friday, the official said about 40 million gallons had been pumped out. He expected the rate would accelerate as more pumps are added.

He said crews are still assessing the damage to the site and don’t yet have a dollar estimate.

But he and others connected to the project say that 1 World Trade Center has several design features meant to withstand the high speeds and flooding that come with hurricanes, including:

• Concrete walls at its foundation that are 6.5 feet thick, reinforced by steel as thick as a human arm
• Beveled edges up and down the tower that will create eight corners, which will “confuse and disperse wind,” and
• The lack of windows for the first 180 feet of the tower —an aspect designed in order “terror-proof” the structure, but will also reduce the amount of water entering through openings.

Additionally, the entire platform for the World Trade Center complex is set to rise 15 feet above grade level, which means that the Hudson River would have to rise at least that high to flow in across West Street. That could be possible in a fierce storm; as it was, Sandy’s 9-foot surge, coupled with high tide, brought the water almost to that height.

Still, Christian Meyer, a professor at the Fu Foundation School of Engineering and Applied Science at Columbia University, said that flooding shouldn’t pose a long-term problem to the stability of the structures since the World Trade Center is built on bed rock.

“As soon as you go off the rock like in Battery Park City,” Meyer said, “the water will go into the sand and create a soil condition. You have to go very deep or it will create instability.”