새로운 폭우 관리 기술이 환경 친화적인 저류지 복원 방법을 찾고 있는 서부 워싱턴 주(州) 도시들을 위해 적용될 예정이다. 해당 워싱턴 주 지역은 오랫동안 환경에 영향을 덜 미치는 폭우 관리 기술을 도입하기 위해 노력을 해왔다.

캘리포니아 주에 등록된 DeepRoot사(社)에서 개발한 기술인 Silva Cell은 큰 나무들이 특수 설계된 지하 프레임을 통해 토양에 접근할 수 있게 함으로서 콘크리트로 둘러싸인 소규모 도시에서도 잘 성장할 수 있게 돕는다. 워싱턴 주 환경 생태 부서에 따르면 위와 같은 기술이 확대 적용될 경우 생태 복원 시설에 못지 않은 효과를 낼 것으로 예상된다.

SAN FRANCISCO, CA, June 21, 2013 -- New stormwater management tools are being implemented in cities and communities throughout Western Washington looking for an effective solution for keeping their watersheds healthy. The area of the state has been a longtime practitioner in low-impact development approaches for stormwater management.

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 a Silva Cell system can have as much impact as a bioretention facility.

"Cities want to surround residents with trees. It improves communities and manages stormwater flow," stated Graham Ray, CEO of DeepRoot. "Many Silva Cells are installed in the Seattle metro area and in Renton and Tacoma, but 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." Silva Cell's designation by the state validates DeepRoot's efforts. The approval also means that contractors can use the Silva Cell on project sites without seeking any additional approval.

The State of Washington has made it easy for municipal planners and urban designers to utilize Silva Cells. In conjunction with local engineering firm HDR, DeepRoot developed a step-by-step design manual for using Silva Cells for maximum bioretention and for maximum impact on the watershed in which trees are installed.

"Because Silva Cells are a structural support system and the soil within the cells can be built to bioretention soil standards, it was clear to us at Ecology that it should be considered equivalent," said Doug Howie of the Washington State Department of Ecology. "Previously, Silva Cells were approved as functionally equivalent to a raingarden; the new designation that Silva Cells are functionally equivalent to bioretention is an important distinction that allows Silva Cells to be used in many more stormwater applications."

The modeling by the state's Department of Ecology found that Silva Cells allow for bioretention of water by supporting the growth of large, healthy trees. They also offer additional flow control benefits  by capturing water with their canopies, evaporations from tree leaves, and enhanced infiltration using bioretention soils.

[출처: Waterworld / 2013년 6월 21일]