Portland’s Green Streets
Sustainable Stormwater Management:
In a natural environment, soil and plants absorb rain. But when streets, buildings, and parking lots cover the ground, rain washes over these hard surfaces. The resulting stormwater runoff carries dirt, oil and other pollutants to rivers and streams and can also cause erosion and flooding that harm properties and wildlife habitat.
Portland uses green streets, ecoroofs, trees, and other green infrastructure to manage stormwater, protect water quality and improve watershed health. Urban streams, forests, and wetlands manage stormwater naturally and are part of Portland’s green infrastructure.
Over one-third of Portland’s 2,500 miles of sewer pipes are more than 80 years old. Green infrastructure protects the aging sewer system and makes it operate more efficiently by keeping stormwater out of sewers.
Green infrastructure brings nature into the city, which can improve both mental and physical health, increase property value, conserve energy, enhance wildlife habitat and save money on more costly pipe infrastructure.
Green Streets are landscaped spaces that transform street surfaces into living stormwater management facilities.
Green streets capture stormwater runoff and let water soak into the ground as plants and soil filter pollutants. Green Streets convert stormwater from a waste directed into a pipe,
to a resource that replenishes groundwater supplies and protects urban watershed health. They also create attractive streetscapes and urban green spaces, provide natural habitat, and enhance pedestrian and bicycle safety.
Landscaping works too:
- Reduce the amount of stormwater runoff that causes sewer overflows and flooding.
- Keep polluted stormwater out of rivers and streams. Portland’s green street projects reduce peak stormwater flows by as much as 85 percent, stormwater volume by 60 percent, and pollution in runoff by up to 90 percent.
- Refresh groundwater supplies and help reduce urban heat islands that cause air pollution inversions.
- Create attractive streetscapes that enhance neighborhood livability by beautifying pedestrian areas and introducing park-like elements into urban neighborhoods.
An image shows how landscapes work
Portland’s Green Streets Program:
Portland’s Green Streets Program started in 2003 with its first pilot demonstration projects. BES studied these projects to evaluate their performance and modify designs before implementing Green Streets more widely. In 2005, a two phase effort was initiated to create the citywide program. The first phase focused on identifying opportunities and challenges to implementation, recommending solutions to key issues, and building public awareness. During phase 2, a citywide Green Streets Policy and Resolution was developed and approved by City Council, processes were formalized for permitting and integration of Green Streets into city plans, and a fund was established to support construction of green street facilities.
Green Street projects have received international recognition and multiple design awards for their innovative approach to integrating functional and aesthetically pleasing stormwater management systems into public space. In 2006, the American Society of Landscape Architects (ASLA) awarded the SW 12th Avenue Green Street Project their General Design Award of Honor. Then again in 2007, two more ASLA Design Awards of Honor were presented to the NE Siskiyou Green Street project and Mt Tabor Middle School Rain Garden. Jury comments for all of the awards highlighted the potential for these designs to be replicated elsewhere and transform how cities approach public space and green infrastructure design.
2003 – First Pilot Projects
2005 – Phase 1 Started
2006 – Phase 2 Started
2007 – City Council approves Green Street resolution, policy, and “One Percent for Green” Fund
Reduce peak flows from their drainage areas by 80 to 94%.
Filter water to reduce total suspended solids by 90%, organic pollutants/oils by 90%, and heavy metals by more than 90%.
40% cost reduction compared to a traditional pipe upsize and replacement project
Three ASLA General Design Awards of Honor
The Program’s Results:
Unknown. (2010). Portland green street program. Retrieved from City Parks Alliance website: http://www.cityparksalliance.org/issues-and-resources/design/case-studies/portland-green-street-program
Unknown. (2010). Portland: a green infrastructure leader . Retrieved from http://www.upperdesplainesriver.org/portland.htm
Unknown. (2010). The green street steward’s maintenance guide. Retrieved from http://www.portlandoregon.gov/bes/article/319879
Unknown. (2009). Sustainable stormwater management. Retrieved from http://www.portlandoregon.gov/bes/34598