- The design of Mint Plaza is contributing in a small but significant way toward improving the ecological health of the San Francisco Bay.
In addition to providing much-needed open space in a highly dense urban environment, the design of Mint Plaza is also contributing in a small but significant way toward improving the ecological health of the San Francisco Bay. Because the City's sewage treatment and rainwater management systems are combined, surges in runoff from storms often exceed system capacity, resulting in the release of untreated sewage into San Francisco Bay. To protect the ecological health of the Bay, the San Francisco Public Utilities Commission (SFPUC) is encouraging the redesign of City streets, buildings and public areas to treat and retain rainfall prior to its discharge into the combined system.
To support this effort, Mint Plaza was specially designed to capture the runoff from its 20,000 sq. ft. surface. A portion of this runoff is collected in two planted "rain gardens" for on-site retention and bioremediation. Additional storm water runoff is collected in a slender slot drain connected to an underground distribution system that slowly infiltrates this water into the sandy soils underlying the plaza surface. Taken together, the design delays, cleanses and retains runoff from small storm events on-site without release to the City's combined sewer system. Larger storm events are also conveyed through the same cleansing and infiltration system prior to discharge to the public storm system.
- A new surface of high-quality, aggregate stone pavers replaced all existing sidewalks, curbs, gutters and asphalt surfaces.
- The design limits the number of trees, vegetation and other fixed objects to minimize shadows, preserve maximum program flexibility and views of the Old US Mint, and to allow for movable public seating.
- A linear, 14’-tall steel “arbor” runs along the northern edge of the Plaza providing a visual transition between the public and private realm and the verticality of the converted warehouse buildings lining former Jesse Street. The architecture of the arbor provides support for flowering trumpet vines and shelter for outdoor café seating below.
- A small “rain garden” planted with a 20’ tall Coast Live Oak is located at the 5th Street edge of the Plaza. This tree serves as a visual cue to passing traffic and provides an important buffer from the rush of automobiles on 5th Street.
- A grove of six Ginkgo trees frames the western end of the Plaza, located at the northern end of Mint Street and visible from Mission Street.
- The portion of Mint Street still open to traffic has been improved with new street trees, landscaped planters and enhanced street lighting.