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How San Francisco schools are digging deep to weather climate change

San Francisco schoolyard gardens planted to harvest rain runoff
San Francisco schoolyard gardens planted to harvest rain runoff 04:13

On average, over 10 billion gallons of rain falls in San Francisco every year. Add climate change and more extreme weather to the mix combined with the city's antiquated sewer system and you can have flooded streets and backed up drains.

Now schools in San Francisco are implementing a creative solution that aims to manage the storm water while benefitting children, their families, and neighborhoods.

If you climb the stairs to the top of Grandview Park in San Francisco, there is a landmark you can't miss with its two pink steeples and striking Romanesque structure. The building marks the spot where neighborhood children have attended school for more than a century.

The school is St. Anne of the Sunset. It's a beloved private Catholic institution of learning located in the Inner Sunset. 

"So many individuals in the community and in the neighborhood experience St. Anne's personally or know somebody who goes there," explained Jennifer VanderWeele. The VanderWeele family is part of the St. Anne's community. 9-year-old Ella and 6-year-old Hugh both attend the school.

CBS News Bay Area was with the VanderWeele family on the first day of the new school year. It started with an early morning breakfast, getting on shoes, brushing teeth, and securing backpacks and lunches before walking to school.

This school year will be different in many ways, but perhaps most notably because of new project that's been in the works since 2019.

That year, the San Francisco Public Utilities Commission awarded the school a large grant to transform its sprawling concrete playground into a storm-water schoolyard.

"We're excited for guys to see it when it's built," exclaimed Sarah Bloom, a senior watershed planner with the San Francisco Public Utilities Commission. The agency has so far awarded 20 grants to San Francisco schools, art organizations and recreational parks.

The main goal for the grant is to help the school divert storm water that has for years run off the concrete and flowed into the sewer system.

"Well, climate change is here, and we're going to see more and more intense storms. We can expect that. And green infrastructure is one of the many tools in our toolbox that we have to manage storm water, especially during these larger storms," noted Bloom.

Last summer, the heavy equipment finally broke ground and construction began. CBS News Bay Area caught the progress over the next few months.

One big feature of the schoolyard is rain gardens. Extreme storms can overwhelm the city's antiquated sewer system, backing up drains and flooding streets. San Francisco's sewer system is a combined sewer system, which means it collects and treats both wastewater and storm water in the same network of pipes.

One way to manage the runoff is to build these special gardens, where the rain soaks into the earth or is captured for re-use.

At St. Anne's, workers created and then planted several gardens. The students were involved and helped select native plants that will be grown in special soil.

"They'll be bringing in specially engineered soil called "bioretention soil." That's a mixture of different types of compost materials and sand that allow the storm water to flow thru it really, really quickly," said Bloom.

The rain that falls on the schoolyard as well as the roof will now flow into the gardens.

Bloom provided a tour around the campus and showed off the garden's different elements, pointing up to gutter on the roof and down to a drain that will direct runoff into the gardens.

"We take that downspout, and we disconnect it and we feed that water straight into the rain garden. So in addition to water coming from the yard and the roof, these rain gardens are doing a lot of heavy work when it rains," she said.

The workers also installed a special permeable pavement that acts like a sponge. At St. Anne's, they used what are called "pavers" and spaced them by filling the gaps with fragments of rocks.

Bloom demonstrated how it works. She pulled out a water bottle and poured water on a paver, which quickly disappeared through the tiny rocks.

"When you pour water on the paver, it will soak right into the ground," Bloom explained. 

Under one garden and completely out of sight, the workers had already installed a large drain known as an infiltration gallery. Here, the structure holds heavy runoff, allowing it to slowly percolate into the soil.

It's a more natural water cycle, and according to Bloom, it goes directly into the groundwater.

Under St. Anne of the Sunset sits the largest groundwater basin in San Francisco called the Westside Basin. The 40-square-mile underground reservoir involves multiple smaller aquifers stretching from Golden Gate Park to the city of Burlingame in San Mateo County.

After months of ripping up concrete, installing pipes, pavements and planting new gardens. the big storms are here.

"So far so good. We've had lots of rain and the gardens have absorbed all the moisture" noted school principal Thomas White.

For an eyewitness report and permission from their parents, Ella and Hugh put on their rain boots and grabbed umbrellas to check out how the new gardens work in the rain. Both were very impressed.

"It gets pushed in over here," exclaimed Ella, showing where the water from the roof gutters flowed into the rain garden.

Her brother was mesmerized by the gardens.

"I really like them. They're beautiful and I see they're taking a lot of water so they can grow," he murmured.

The rain gardens will be incorporated into class projects. Some of the students' mothers plan to do some gardening and weeding.

"It's been a really wonderful project to create more green space and to make the school environment more enjoyable, but also for the kids to get more engaged and become more aware," explained Mrs. VanderWeele.

The SF PUC is currently accepting new grant applications. To date, the agency has awarded 20 properties with a total of $20 million. Once complete, these projects will divert nearly 13 million gallons of storm water – enough to fill more than 19 Olympic-sized swimming pools. 

The agency is also testing a residential pilot program.

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