DeepRoot's Silva cell allows big and mature trees to grow in urban spaces. Now certified by Washington State as functionally equivalent to bioretention in managing stormwater.

Managing stormwater runoff is a problem vexing US and global urban areas. When rain falls, most urban environments struggle to manage the flow, which can quickly overwhelm sewer systems, and to use the rainwater as a valuable resource to support urban trees and plants.

Now, western Washington, long a leader in low-impact development approaches for stormwater management, has recognized a new tool for cities and communities that want an effective solution for keeping their watershed healthy – the Silva Cell.

The Silva Cell, developed by DeepRoot, is an underground frame that allows large trees to have soil access so they can grow healthily in a small urban space, even if surrounded by concrete. The Washington State Department of Ecology found, through extensive modeling, that this system can have as much impact as a bioretention facility.

"Cities want to surround residents with trees," said Graham Ray, CEO of DeepRoot. "It improves communities and manages stormwater flow. Many of our cells were installed in the Seattle metro area and in Renton and Tacoma. Now that we are certified by one of the nation's most influential state agencies, we hope people will realize just how effective a tool this is for absorbing water from ordinary storms – even in places where it rains every day."

Western Washington has a regional consensus to protect the purity and clarity of Puget Sound. The state has therefore developed some of the highest standards and requirements for any product or project to be designated as a stormwater management solution. The cell's designation by the state validates company efforts. The approval also means that landscape contractors can use this product on project sites without seeking any additional approval.

To view the letter the Washington State Department of Ecology, please visit: https://bit.ly/WASilva