During the heavy rainfall season, San Francisco faces some daunting challenges: Draining the water, keeping the roads from getting slippery, and containing and treating the runoff. Some storms are so severe that the city can't keep pace. That's when we see flooding in the Muni tunnels and sewage discharges into the bay.
But the solution -- or at least part of the solution -- could be as simple as changing the material that we use to pave our streets.
The city considered a wide variety of low-impact-design techniques for managing water at community meetings held in 2007. Among the solutions was permeable pavement, a technique dating back centuries that fell out of favor during the fast-and-cheap highway booms of the last few decades.
As Miles Chaffee, President and founder of Milestone Imports explained to Streetsblog, the benefits of permeable paving are numerous. "It decreases impervious land coverage, provides a more stable load-bearing surface, and allows the water to go into the ground," he said. "It eliminates the need for detention ponds, which require additional space. And it takes off a lot of stress from the sewer systems when it's done correctly."
In addition, permeable paving can be made lighter in color, which reduces the urban heat island effect. It can be made of recycled materials, such as concrete and rubber, and by filtering the water, it removes pollutants. There are advantages for bicyclists as well: "It takes that film of water off the ground that makes it slippery," Chaffee said.Read more...