Chapel Hill experienced a “high intensity rainfall” on June 30th, 2014. While it’s no surprise when a series of storms cause gushing rain water to leap out of culverts and normal channels, the flash flood that followed was the surprise. It arose and disappeared quickly but it damaged homes, eroded hillsides and yards, and felled trees by eating away their root system. The damage will not be easily repaired.
It’s simple physics — when the rate of rainfall exceeds the drainage capacity of a given area, then water gushes downhill way faster than the channels can handle. The more water, the faster it moves. And it gushes faster still if it hits roof tops, roads, and parking lot or any hard surface instead of sinking into a forest floor to replenish ground water supplies. Chapel Hill’s latest strategy has been to require stormwater facilities on new development that will mimic nature by slowing rainwater and keep it on site. Clearly this was not possible in a 6 inch rainfall. But the storm damage suggests that we need to reevaluate our current infrastructure to see how we can prevent a re occurrence of this damage.
Here is a pictorial story of the rain garden that was intended to capture some of the stormwater from the beautiful new Chapel Hill Public Library. Sadly, this brand new stormwater facility failed, sending stormwater and sediment downstream. See picture story here.
WCHL tells the story on Chapelboro here.