Green Streets

Project featuring attractive curbside planters that absorb flash flood water run-off - essential in a city with nearly a metre of rainfall each year.

The north American city of Portland has an average of 98 centimetres of rain a year. With such high rainfall, the city authority is understandably keen to manage water run-off and protect water resources, such as the Willamette River. One of its most innovative initiatives is the Green Streets project, which was piloted in 2005 along 12th Avenue, a street that runs through the university campus. The street’s pavements were retrofitted with a series of specially designed planters that collect storm water, filter it, divert it away from the usual stormwater drain – which runs directly into the Willamette River – and instead allow it to be absorbed gradually back into the water table.

The planters have proved to be able to capture almost all of the street’s run-off, preventing flash floods and reducing the amount of water that the city’s drainage system has to deal with. In addition, they have been planted with attractive shrubs and trees that provide shade, air-cooling and colour to the street. It is this combination of enhancing the urban environment with providing a sustainable urban drainage system (SUDS) that has ensured the scheme is award winning and being replicated across Portland and other US cities.