Think BIG! How GSI can manage big stormwater flows from Big Roofs by GrIP


Thursday, Oct. 18th from 2pm – 4pm we heard from RainWise program manager Tom Gannon about how GSI can manage big stormwater flows from “Big Roofs.” To be considered a “Big Roof,” the roof must exceed 2,000 sq ft.

There was a wonderful turnout of community leaders and members interested in how we can work to improve and protect our waterways!

This presentation was held at St. Luke’s Episcopal Church in Ballard and included a tour of St. Luke’s RainWise installations. A huge, beautiful rain garden and giant water catchment facilities are only part of how this hard-working group of wonderful people contribute to improve life for all around as they also run a community garden and housing facility.





These water catchment systems are just incredible! Not only are they providing harvested water for the surrounding gardens, they are also working as a stopping point and holding water during storms to prevent it from flowing freely across concrete and streets and entering the Sound.

And just a reminder; September – May is when low-flow valves for cisterns should be opened! Don’t forget to check if your gutters or screens need to be cleaned as well.


This very large rain garden at St. Luke’s was installed in 2017 by DIRT Corps (Duwamish Infrastructure Restoration Training). Such a beautiful job and such a great way for the community to come together and learn how to maintain it.

We also checked out a current large GSI project in progress in Ballard that involves the installing of a HUGE wastewater runoff collection tunnel.


The tunnel will span along the Ship Canal from Ballard to Wallingford, a 2.7-mile stretch into which nearly 80 million gallons of polluted water each year spills from surrounding neighborhoods. According to SPU, the 18′ diameter tunnel will capture and temporarily hold polluted stormwater and sewage that overflows during heavy rains. Flows will then be sent to King County’s wastewater treatment plant to be treated and discharged.

Read here to find out about exciting current GSI projects!

spu01_006283Not familiar with RainWise? Here’s the rundown!

Stormwater runoff presents the biggest threat to water quality in the Puget Sound. Seattle Public Utilities and King County offers a solution: the RainWise program. This program allows both homeowners and “big roofs” to mitigate stormwater runoff to help save Puget Sound. “Big Roofs” are defined as community centers, religious organizations, apartment buildings and businesses.

The RainWise Rebate Program offers the opportunity to have up to 100% of the cost of your rain garden or cistern installation covered. Reach out today if you’re interested in a rain garden or cistern of your very own! You should also check out GrIP and come to a meeting, we’d love to see you!🤗💚🌎

The Green Infrastructure Partnership (GrIP) is a group of nonprofits, government agencies, community-based organizations, and businesses who deliver green solutions to stormwater pollution via education, technical assistance, and incentive programs. Our goal is to offer networking, education, and collaboration opportunities that bolster voluntary green infrastructure implementation in the Seattle area as an affordable and effective solution for preventing polluted stormwater runoff in Puget Sound.

GrIP meets on the third Thursday of each month to offer expert presentations on GSI topics of interest to our participants. We also provide time at each meeting for participants to share news about their project work as well as an opportunity for networking with those present.

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