Saving the Planet with Sidewalk Gardens

Sidewalk stencil, SF artist unknown

I started this blog a few years ago, after I was laid off from my landscape architecture job and needed an outlet for discovery. I spent a lot of my time walking around San Francisco, geeking out. San Francisco Sidewalks is where I could write about the  little pockets of individuality within the  uniform expanse of concrete I found through the city. Recently I’ve been blessed with the opportunity to use my passion for adding a touch of personal space to public space by busting up some sidewalk and replacing it with beautiful gardens.

Over 5 years ago the San Francisco Board of Supervisors passed legislation to allow excess concrete sidewalk to be removed.  In 2006 Mayor Gavin Newsom signed into law, the “Permeable Sidewalk Landscape Permit” – revolutionizing the city’s largest public space. Now for $215 (discounted to $160 if 5 neighbors submit together) a property owner can get a permit through the Department of Public Works, Bureau of Urban Forestry and transform exess sidewalk into beautiful gardens!

But its not just about passing pretty gardens as you walk to the corner store. Creating permeable surfaces completes the natural water cycle of our planet – allowing rain and know to soak into the ground and waterways where its naturally filtered and cleansed before it makes its way to ocean and is evaporated into the atmosphere and becomes rain and snow again.

Affects of Urbanization on the SF watershed, from SF PUC

Covering the ground with concrete, asphalt and buildings disrupts the Earth’s natural water cycle. Instead of filling underground aquifers and waterways, rain fills sewers that often overflow in big storms and dumps minimally treated sewage into rivers and oceans. Its bad enough to have pathogens, and toxic chemicals and dumped into the ocean and San Francisco Bay, but minimally treated sewage also destroys the natural ecology of water bodies. The nutrients in sewer overflowstimulate algae and other plant growth, decreasing the level of oxygen in the water and causing the ocean and bay ecosystem to die.

This is particullary an issue in San Francisco, one of the only cities in California that is served by a combined sewer system, where both sewage and stormwater is collected in the same network of pipes. treated and then discharged into the San Francisco Bay or the Pacific Ocean. Most other cities have separate sewer systems; one set of pipes takes sanitary waste to the treatment plant while a second set carries storm water runoff from street drains directly into creeks, lakes, or the ocean.

The combined sewer system moves 80 million gallons of wastewater a day on non-rainy days, according to the PUC.  But in a rain storm, the sewers can fill with 500 million gallons a day, resulting in minimally-treated sewage overflowing into – and polluting – the bay and/or ocean throughout the rainy months. If you are a surfer or a masochist and like to swim in the frigid bay, you can check if there has been a sewer discharge at your favorite San Francisco beach here.

This is where busting up concrete comes in.

26th Street and Shotwell, Mission, SF

Maybe its a bit of an overstatement to say that sidewalk gardens can save planet, but clearly disrupting the water cycle is destroying our planet. And there is a simple solution. Reducing the amount of pavement that rainfall encounters, reduces the amount of runoff that goes down the drain and into our combine sewer system. Opening the pavement allows more storm water to be absorbed into the soil, and reduces strain on the infrastructure. In the west side of the city, it allows water seeping into the ground to replenish the underground aquifer, which someday the PUC hopes will supply some of our drinking water, easing our dependence on Hetch Hetchy.

And so, just maybe, protecting the ecosystems of our ocean and bay and adding to our potable water supply could someday save our city. And the benefits of sidewalk walk gardens don’t end there.

Lincoln High School, Sunset, SF

I know that I’m probably preaching to the choir here, but I gotta to say it anyway –  in addition to repairing the Earth’s water cycle, sidewalk gardens provide a habitat for birds, butterflies and bees, pollinators and important members of  our ecosystems. They remove CO2 from our atmosphere and sequester it in vegetation – important to do along our roadways.

What you might not know, is that sidewak gardens improve neighborhoods. They create unique and cohesive  streets and brings neighbors together. Its been documented that gardens reduces crime in San Francisco by improving community vigilance, awareness and ownership. Realtors say that sidewalk gardens increase property values. And a Mission business owner says he’s had more business and pedestrians walking by since sidewalk gardens were installed a few months ago.

Neighbors planting on York Street, Mission, SF

I love transforming San Francisco, block by block. Last year I helped remove over 3,000 square feet of excess concrete, and it has been a dream come true. The icing on the cake, is that the sidewalk garden installations are almost completely subsidized by local and federal grants, so that the sidewalk garden installation is very affordable for property owners. For this reason, the sidewalk installations have been a community event, an entire block comes out to plant their gardens and then celebrates with a potluck lunch. For more information about installing sidewalk gardens, check out the Friends of the Urban Forest website.


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