September 27, 2022 6:56 am

Posted: 22.1.2022 1:12

Colony Ridge and Plum Grove: 100-year flood on 5-year rain


I visited Missy in Plum Grove earlier this week and she gave me a tour of flooded areas.
She also gave me an elevation certificate for the City Hall property that showed it was in “shaded zone X” on a 2008 flood survey (before colony ridge). That means it should have an annual flood chance between 1% and .2% (100-year and 500-year floods). She said the survey was taken before the City Hall building was built. So they shot the elevation from the parking lot or surrounding property. But water covered that property during the flood they had on Jan 8/9.
According to Atlas 14 rainfall statistics and the gage at FM2090, that was only a 5-year rain.
So they got a 100-year flood on a 5-year rain!  Hmmmm.  Remember those Colony Ridge engineering reports!!!!!
Here’s a post I wrote about it within the context of recommendations by the Association of State Floodplain Managers.