San Francisco, CA
21st Street, LLC
Our clients are interested in integrating water re-use into a new residence on a sloped site which lies on bedrock without infiltration. We provided civil engineering and integrated water and building systems engineering, working with the architect and landscape architect to seamlessly combine innovative infrastructure with a strong formal design.
All graywater flows passively into a large biofilter at the low-point of the site, where vegetation surrounds an outdoor deck; pressurized irrigation lines send treated water to a series of 4 living roofs, where secondary treatment occurs through our customized "blue roof" system (up to 5" of graywater are held in aerobic and anaerobic conditions, which simulates a tidal wetland where plants and soil decompose remaining organic compounds). In this way, roof run-off combines treated graywater and rainwater into a storage tank sized to serve as a source for indoor toilet flushing and laundry, while simultaneously providing space to accommodate stormwater retention on our site and offset run-off.