Elegant water drainage methods: Levi Plaza in San Francisco and elsewhere

Walking to the Embarcadero in San Francisco provides an opportunity to visit Levi’s Plaza Park, a tranquil and beautiful refuge that makes the nearby traffic almost disappear. On a very rainy day in San Francisco this January, we visited the empty park, walked around, and admired the brooks, fountains, and an ingeniously designed drainage system. The physics of drainage revolve around the hard fact that the erosive power of water is proportional to the fifth power of the water’s velocity–double the velocity and the erosion goes up 32-fold! (See our discussion below)

My photographs show the diversion of water flow along the walkway margins, with elegant rip-rap breaking the velocity and swales directing the flow of water towards larger streams, a pool, and, ultimately, large drainage pipes.

Drainage is always an issue when installing large outdoor sculptures. In our work, we want to avoid water pooling at inappropriate places around the piece and also to prevent nearby erosion. Freeze-thaw cycling in New England makes the drainage issues more complex.