In one hour last Wednesday 1.58 inches (4 cm) of rain fell in Marysville, Washington, near Seattle. The deluge overwhelmed the stormwater system, flooding streets and the Public Works Building with up to 18 inches (45.72 cm) of water.
Severe rain events have increased 16% in the Pacific Northwest and 20% nationwide in the past 100 years, and are projected to continue to increase. Overall nationwide precipitation has increased 5% in the past 50 years, stressing already crumbling stormwater infrastructure.
The main culprit: impervious surfaces.
Solutions do exist, however, and the good news is they typically cost less than end-of-pipe stormwater management. [Read more…]