Key Findings
- Vegetated streetscape facilities (“Green Streets”) designed to handle runoff can filter water, remove pollutants, and reduce demand on stormwater infrastructure.
- Green Streets can also serve as urban greenways that enhance the pedestrian environment, provide wildlife habitat, reduce summer air temperatures, and replenish groundwater aquifers.
- Green Streets can be more cost-effective than traditional pipe upsize and replacement projects.
- Development of sample designs, standard details, policy, and technical guidance documents support implementation by the private sector.
Organization description
The City of Portland’s Bureau of Environmental Services (BES) provides Portland residents with a range of water quality protection, planning, and educational services. It is composed of five work groups: Watershed Services, Pollution Prevention Services, Engineering Services, Wastewater, and Business Services. These groups monitor and test the performance and design of pilot stormwater projects and provide technical assistance to developers and designers who are incorporating stormwater measures into site designs. They partner with property owners (commercial, industrial, and institutional), local public agencies, and the federal government for project design, funding, and implementation. BES also develops supporting policy and provides project documentation, outreach, and public education. Their comprehensive approach has made Portland an internationally recognized leader in stormwater management.
Program description
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 the construction of green street facilities.
Technical guidance documents with standard construction details, designs, and recommended plantings have also been developed and published on the Green Streets web site. The details are provided in both PDF and AutoCAD format, making it easy to adapt the designs to fit new projects and locations. The web site includes illustrated reports describing various completed Green Street projects in terms of their design, cost, site selection, stormwater capacity, plants, maintenance, monitoring, successes, and lessons learned.
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.
Program goals/issues addressed
As stated on their website, The Green Streets Program:
- Reduces polluted stormwater entering Portland’s rivers and streams
- Improves pedestrian and bicycle safety
- Diverts stormwater from the sewer system and reduces basement flooding, sewer backups and combined sewer overflows to the Willamette River
- Reduces impervious surface so stormwater can infiltrate to recharge groundwater and surface water
- Increases urban green space
- Improves air quality and reduce air temperatures
- Reduces demand on the city’s sewer collection system and the cost of constructing expensive pipe systems
- Addresses requirements of federal and state regulations to protect public health and restore watershed health
- Increases opportunities for industry professionals
Timeframe (Planning/Execution)
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
Annual program budget:
Construction Budgets for individual projects are available on the Green Streets website.
Funding sources and type of support provided
The “One Percent for Green” fund supports construction of Green Street facilities. This fund is raised from one percent of the construction budget for any projects requiring a street opening permit (with certain exceptions). BES also received funding support from the EPA for initial implementation of their Green Streets program.
Results achieved/impact:
- Green Streets have been shown to reduce peak flows from their drainage areas by at least 80% and up to 94%.
- Green Street facilities 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
