More Green Roofs Coming To Seattle

Seattle, Washington's mayor, Mike McGinn, announced a plan which is designed to handle up to 700 million gallons of storm water a year using "natural systems" instead of traditional "pipe-and-tank" systems. One of the main ways this will be achieved is by adding more green roofs to the city.

The executive order, which the mayor's office said is among the first of its kind in the country, directs city departments to develop a coordinated approach to significantly increase the use of natural drainage systems to slow and clean polluted waters by filtering the water through vegetation and soil.

The storm water infrastructure approaches are to include bio-retention swales, rain gardens, storm water cisterns, pervious pavement and green roofs.

A news release from McGinn's office states that the "green storm water goal" will be achieved through a combination of city-led projects on public land, "code-triggered private sector investments" and voluntary actions on private property.

Pam Emerson of Seattle Public Utilities said "code-triggered" refers to existing requirements. Any new single-family residential project that goes through a storm water code review must implement green storm water measures "to the maximum extent feasible," she said.

Other projects that already are required to do this are those with 7,000 square feet or more of "land-disturbing activity," or with 2,000 square feet of impervious surface.

Emerson said it is possible that code requirements will change between now and 2025, when the goal is to manage 700 million gallons of storm water with green infrastructure. Today, a little more than 100 million gallons of storm water is filtered through rain gardens, green roofs and swales.

The City Council will consider the mayor's new goal in a resolution later this month, McGinn's office said, adding that council members support the idea.

"I am confident this initiative will be another success in the city's groundbreaking environmental history," Councilmember Jean Godden said in the news release. She noted that Seattle implemented the first recycling program in the country and said, "I know our residents will be behind this effort."