New York (CNN) -- Engineers working on the September 11 memorial took a giant step this week when they began testing one of the installation's twin waterfalls.
The north pool waterfall, located where the North Tower of the World Trade Center stood, sprang to life Tuesday after years of planning by the National September 11th Memorial and Museum.
The waterfalls, designed by architect Michael Arad, will be the center of the "Reflecting Absence" memorial plaza, which is to open on September 11, 2011, the 10th anniversary of the fall of the twin towers. By then the falls are to be surrounded by a green space and framed by 400 trees.
Joe Daniels, president of the memorial, said he was on the site when the tests began.
"To see the water coming down all four sides of the north memorial pool took my breath away," he said. "To see the veils of water fall in the pool was inspiring. It was great."
The waterfalls are the largest manmade falls in the United States. The fall is 30 feet, and the water eventually disappears into a 15-foot void in the center. The victims' names, emblazoned in bronze and illuminated at night, are carved into parapets just behind the falls.
Each fountain will hold 480,000 gallons of water that will take 22 minutes to circulate. The water pressure and pump system will be tested intermittently; the south fall is scheduled to be turned on in the spring. Once the memorial opens, the fountain will run continuously, helped by a steam heating system that will keep the water from freezing, according to the Port Authority of New York and New Jersey, which oversees the site.
Port Authority spokesman Steve Coleman described the progress being made on the facility.
"They're almost finished building the memorial pavilion, the entrance where you go below the plaza level to see the artifacts in the museum, which will be beneath the falls of the plaza," he said. "The street level plaza, green space and fountains will all be open by next September 11, 2011. The underground portion will open the following anniversary date in 2012."
Memorial spokesman Joe Daniels estimates that 5 million visitors will make the site part of their New York City itinerary each year, which would make it the top tourist destination in New York.
In addition, he noted that the space adds a very valuable commodity for those who work and live in lower Manhattan: peace.
New York City "is an incredibly vibrant place to be, there's lots of different sounds," he said. "But when you're at the memorial pools there's something special and nice about hearing the ocean wash that separates you from your surroundings, which reminds you of why you've built it."