It’s nice to hear a rushing creek…but when those creeks are full of stormwater runoff, it’s not necessarily a pleasant sound. At least to Sandy Mathews, Alameda County’s Clean Water Program Manager.
"What we’re really focused on is water quality. Keeping the stuff that’s in our everyday lives—like the oil drips, the dirt from construction sites—out of the stormwater."
That’s because stormwater isn’t “treated” the way that wastewater typically is.
"And when you’re in an urban environment like we are in the Bay Area, a lot of that stormwater hits the ground, but it doesn’t get into the ground. It runs off. It runs into storm drains. And those storm drains are fast conduits into the creeks and into the Bay."
That’s why folks, who surf or swim in the Bay, are advised not to go right after storms: surplus stormwater can make the Bay toxic. Historically, storm water has been considered waste water. But that thinking has been shifting over the past few years.
"It used to be that engineers wanted to get the water away from people and away from buildings as fast as possible. And now we’re trying to keep it."
Now the entire state is giving stormwater some overdue attention. Last October, the Governor’s office signed legislation to ramp up water resilience strategies. Sandy Mathews said that includes “green infrastructure” projects, like the ones you can see here, in an unassuming spot in Hayward.
"We are here at the Alameda County parking lot for their Corporation Yard…"
The idea behind all of this green infrastructure is “Slow it. Sink it. Spread it.” These designs do that by capturing water and “ponding” it. Sandy Mathews tells us how it works.
"So, right here, this is called a bio-retention area. And what we’re doing here…as you get closer you’ll notice there’s a drop off from the pavement into the landscape area, and that’s so the water can be ponded there and be captured. And underneath these pretty plants are is a bio treatment soil media that’s going to clean up the water. And below that is a layer of about twelve or so inches of gravel material that’s going to be a reservoir and is going to hold the water before it makes it to the soil underneath."
This demonstration site has examples of porous concrete and permeable pavement….
"You could nerd out on this. Big time."
Cities that are specially designed to handle the rainwater that hits them— and beneficially re-use it — have a name: “sponge cities.”
"Are there any “sponge cities” here in the Bay?"
"Not yet, but maybe we're growing towards that..."
But we can still soak up stormwater’s benefits. Rain gardens are something people can create in even the smallest slivers of urban space...including your own backyard.
