Vegetated Sand Filter. Tanner Springs Park in the Pearl District of downtown Portland, Oregon is a modern-day experiment in sustainable design and stormwater management. The water feature, designed by Herbert Dreiseitl is an effort to re-create the pre-industrial wetlands and riparian ecology of the original Tanner Creek that flowed to the nearby Willamette River in the early 1800s. One sustainability feature of the park is the collection, treatment and recirculation of all rainwater that falls within the park. Additional sustainability features include the re-use of basalt cobbles, or Belgian Blocks, for walkways and the re-use of rusty railroad rails for the undulating wall.