12th Street Rain Gardens

Surface water enters this rain garden through curb cuts.

Located at two intersections within the financial and government districts, two landscape bumpouts were created to collect runoff from two City blocks and filter sediment and heavy metals from stormwater prior to infiltration into the subgrade or overflowing into the existing storm sewer system. The design included working within the current Public Works sidewalk and curb details to create bumpouts with depressions for collecting and storing water for short periods of time. Runoff from the curb and gutter, street and sidewalk are encouraged to enter the basin/garden through curb and planter wall cuts. A concrete forebay was created to collect sediment. The concrete bottom creates an easy surface to scoop dirt and debris for easy maintenance. The planted area includes 12-24 inches deep engineered soil containing 80% sand, 15% sandy loam soil, and 5% organics.

The gardens were planted with ornamental grasses, blue flag iris, and decorative rock. The ornamental grasses (dwarf variegated maiden grass and Karl Foerster Feather Reed Grass) will have year round interest with color, texture, late summer blooms and turning a rich gold in the fall. These grasses can remain standing upright during a heavy snow and have minimal maintenance throughout the year.

Project was designed by BNIM Architects.