Friday, September 23, 2011

Trees as Storm-fighters

1 APRIL 2011

ONE WAY THAT trees help cities: a neighborhood with lots of mature trees needs less maintenance of underground storm drains and tunnels.

Here are two storm-fighting trees Restore Mass Ave planted with our partner Casey Trees in March. In the foreground is a Northern catalpa (C. speciosa). Behind is a swamp white oak (Q. bicolor).

Above: Northern Catalpa (C. Speciosa) tree (Photo: Restore Mass Ave)

Don’t they look fragile? But thanks to care by the Church of the Pilgrims, which abuts this land, these trees will grow into big, spreading structures that lessen water runoff onto 23d Street (on the right) and down to Rock Creek.

That is why we planted next to Rock Creek valley. We’re especially glad that the Park Service gave permission for these trees, because after the planting, we learned that there will be a one- to two-year project to replace the underground pipes taking storm water down to the creek here.

The city’s old combined sewer and storm system (CSS) backs up in storms. In sudden drenching storms sewage etc., instead of flowing through the system to the Blue Plains plant, overflows into the Anacostia and Potomac rivers and Rock Creek. One outflow pipe is by this location.* As part of a pipe and tunnel upgrade that’s six year’s on, these deep old pipes will be replaced.

Billions of dollars in new tunnels and pipes isn’t the only way to get our watershed to meet federal standards (finally). Greenroofs and bigger sidewalk tree boxes can stanch the water volume burdening the system and lessen maintenance costs. So will more trees strategically planted in open land.**

Basta about sludge!

Below are the flowers of a mature catalpa tree, white and trumpet-shaped in showy arrays. Catalpas grow 40 to 50 feet tall and spread 20 to 40 feet wide. With large trees, about a third of all rainfall is caught by the leaves. The trunk takes up more, while the root system carries much of the rest down in the ground.

Above: Catalpa flowers (Photo:  Mvia45)

This is Nature’s plumbing, working for us.

*The CSO 36 upgrade is part of DC Water’s Clean Rivers Project.   Go to for updates.

**A report on how DC can lower system burden by greenrooves and trees is Casey Trees, Limnotech WASA (2008)



Thanks to the Casey Trees staff for this imaginative choice and arranging to plant on this site.

Thanks to Church of the Pilgrims, especially Ashley Goff, for maintaining these and other new trees near the church.

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