"It's the same principle as siphoning, but [the water] needs some help along the way," Miller says. "The water is draining to a higher level than you are coming from."

The pipes run on a slight incline toward the river before rising sharply to clear the levee. Miller says once water reaches the other side, it helps siphon the rest of the water over the top. The Corps created a scale model using water flow and volume to determine what it would take to prime the pipe. Miller says they then worked with a manufacturer to construct customized pumps to move the water at the right velocity. With such large pipes and the weight of the water moving across the levee, the design required the contractor to first widen and fortify the levee with concrete supports. After pipes are laid across the levee, they will be placed back underground for the span to the discharge basin.

Miller says the key to making the siphon work is to keep the pipe filled with water and eliminate air pockets. This was accomplished by designing the system with numerous shutoff and release valves. In the case of a big rain, the streets will drain to the pump station, which then starts to fill the pipe with water. Once the pipe is filled up to the levee, the system is primed and siphoning can start.

"It was a little complicated in that sense," Miller says. "You don't want air trapped in the pipe. We did a lot of studies to see what it would take to prime [the pipe]. If the pump isn't pumping hard enough and you have air, it won't work."

Despite a few delays and engineering challenges, Calico says the project is on track for a 2017 completion.