St. Emydius Church is set to build four rain gardens and an underground infiltration gallery that can hold up to 7,800 gallons of extra rainwater in 2023. 

Rain gardens are an area in the landscape below street level that collects and soaks up rainwater from streets, roofs, and pavement. When planted with greenery and flora, rain gardens provide a beautiful way to reduce water runoff from the surrounding environment.

Unmanaged water runoff dirties the moment it hits the ground, picking up oils and chemicals from the road, and waste. During very large storms like the recent week-long rain in California, the sewer can be overwhelmed by stormwater runoff, and the untreated water discharges to nearby streams, rivers, and other water bodies.

With the local effects of climate change intensifying and increasingly affecting San Francisco, every drop of water could help.

“Water capturing systems are great in cities because they reduce atmospheric temperature,” said Michael O’Brien, the AP Environmental Sciences teacher at Riordan. “They help cleanse the air, and manage water more sustainably.”

St. Emydius’ green infrastructure enhancements are designed to gather and manage runoff from almost an acre of paved surfaces, or close to 12,000 bathtubs of water.

The new furnishings will be completely provided at no cost through an $873,000 grant from the San Francisco Public Utilities Commission, according to Greenprint Partners, the green infrastructure engineering firm developing the project.

Although teeming with upside potential, there still is doubt of the effectiveness of this new green engineering.

“It seems like a waste of resources, but it’s not hurting anybody,” said AP Environmental Sciences student Colm Grieb ’24. “We’ve had one bad week of rain in over a year and everyone is taking drastic measures to prepare for the next one that might not happen for a while.”