A typical greenstreet facility in Portland, Oregon. This one compines a stormwater treatment facility with a bulbout to reduce pedestrian crossing distances. Photos: Portland BES.
When Streetsblog San Francisco took part in the Congress for the New Urbanism's Project for Transportation Reform
in Portland last week, city planners and transportation engineers treated participants to numerous tours of innovative network solutions that city has embraced, including its greenstreets program
for stormwater treatment on street rights-of-way. With nearly five hundred greenstreet facilities already in the ground, Portland has plans to add another five hundred in the next five years, greatly reducing the burden stormwater can place on its sanitation system.
Portland's greenstreet facilities often take up multiple on-street parking stalls and replace the asphalt with beds planted in native species that help absorb significant volumes of streetlevel wastewater, near 100 percent in some locations. Facilities include swales, curb extensions, planters, and infiltration basins, and are typically linear and pool 6 to 9 inches deep [PDF].
David Elkin, a Landscape Architect working for Portland's Bureau of Environmental Services (BES), explained on the tour that the first experiments with greenstreet facilities in Portland were necessitated because the city had to meet mandates in a Clean Water Act lawsuit for polluting the Willamette River, which flows through Portland. The city faced the challenge of increasing the number drainage pipes in east Portland, at a cost of $150 million, or develop another solution for reducing "upstream" water volumes, those that came from surface streets. By adding the greenstreet facility network, which initially cost $11 million, the city met its target stormwater capture and estimated that it saved $60 million in pipe replacement costs.
"We can talk about all the multiple benefits that greenstreet facilities provide, but the bottom line is it saves taxpayers dollars," said Elkin, noting that the first on-street facility was installed in 2002. "Instead of just a patch or trench in somebody's street, we're going to leave behind a green, vegetated facility."