Green Infrastructure

CREATING GREEN INFRASTRUCTURE

Portland, Oregon has been figuring out ways to lessen its carbon footprint and develop sustainably for nearly two decades. At the same time, it's already too late to stop some of the impacts of climate change. To prepare for inevitable changes, the city is rethinking how it manages its stormwater. Portland gets 37 inches of rain a year and climate change predictions suggest it may be getting a lot more in the not too distant future.

As much as half the surface of Portland that was once porous, is now covered with impermeable pavement and rooftops. Portland's Bureau of Environmental Services (BES) has developed a number of programs that try to compensate for loss of permeable urban surfaces by creating "green infrastructure." Green infrastructure, like traditional grey infrastructure—the pipes and concrete that have historically disposed of urban storm water—is a way of managing storm water. But green infrastructure turns what was once considered a waste into a resource. By mimicking nature using ecoroofs, rain gardens, curbside swales and planting lots of street trees, BES hopes to recreate some of the natural systems that worked so well before the city was built.

oaks bottom

Natural areas, like the 160-acre Oaks Bottom Wildlife Refuge in the Sellwood District of SE Portland, are the best stormwater receptacles a city can have. Portland is fortunate to have preserved and protected a significant amount wetlands and forests. There are no engineered solutions that can quite match nature.

There are several ways to re-create natural hydrological systems in the city:

clay st. swale

This curbside swale and curb extender at the corner of SE Clay and 12th in SE Portland serves the dual purposes of infiltrating stormwater from the adjacent paved surfaces into the ground as well as creating a safer pedestrian crossing at this busy intersection. Capturing stormwater on site rather than sending it into pipes that eventually shoot the water into the Willamette River as waste, helps keep the river cleaner and also provides flood control.

porous path

This garden path is made from broken concrete pieces that came from the original concrete walkway. Porous pavements, such as this path, and driveways and parking lots made from paving stones, allow rain water to infiltrate into the groundwater, almost as efficiently as it did before the city was built.

rain garden

Raingardens are landscaped areas that collect and manage stormwater. They are also attractive neighborhood amenities that provide wildlife habitat.

ecoroof

Ecoroofs are another means of capturing rainwater on site, rather than having it drain off rooftops into storm sewers. An ecoroof consists of a layer of vegetation growing in soil on top of a synthetic, waterproof membrane.

PDX building

This ecoroof is on top of the Portland Building in downtown Portland. On the tenth floor of this building are the Evironmental Services office.

planter

Stormwater planters collect stormwater runoff from roofs, streets, driveways and sidewalks, slow the flow, and allow water to soak into the ground as soil and vegetation filter pollutants.

street trees

Street and yard trees capture and hold rain as it falls, reducing stormwater runoff, creating habitat and cooling the environment. When developing a site it's important to preserve existing trees.

This whimsical sculpture is part of rain catchment system at a New Seasons Market in SE Portland. Storm water from the market's parking lot and roof are channelled into curbside and parking lot swales. This scupture catches rain from the rooftop and feeds it into a swale.

forest park

Forest Park in NW Portland, a couple miles from downtown, is more than 1,600 acres of wilderness. Another major asset for making the city more sustainable.

great blue

A great blue heron, who makes its home in Oaks Bottom Wildlife Refuge.

Portland's Environmental Services programs are serving as models for other cities around the country. To learn more about how you can landscape your yard to promote sustainability and miminize stormwater runoff, check out: http://www.portlandonline.com/BES/index.cfm?c=34598