The falls will be the tallest in North America. Photo Credit Amy Dreher

The largest man-made waterfalls in North America are nearing completion, and the first cascades successfully flowed in the north pool in last month. The waterfall testing let engineers assess for the first time the actual flow and circulation of the water. For several hours, water flowed through eight pumps, circulating about 52,000 gallons of water per minute.

The 176-foot-perimeter pools mark the footprints of the World Trade Center’s original twin towers. Entitled “Reflecting Absence,” they were designed by architect Michael Arad as the centerpieces of the National 9/11 Memorial plaza.

More than 50 trees already have been planted on the plaza around the pools since August. Meanwhile, the entrance pavilion steel is nearly complete at the center of the WTC site, with the two iconic “tridents” from the north tower’s façade now in their permanent location.