The drainage system worked, just not quickly enough to prevent water backing up, they said.
Last Friday's downpour that flooded numerous local streets and Interstate 55 was an extraordinary event and not an indication that the city's drainage system is inadequate, Cape Girardeau officials say.
"What you saw in Town Plaza and around town we haven't seen in five to 10 years," said Mayor Jay Knudtson. "Basically the sky opened and dropped rain squarely on our city."
Early Friday afternoon 2.7 or more inches of rainfall hit Cape Girardeau in approximately an hour. The public works department closed 26 intersections or portions of streets and the police department responded to 38 traffic accidents during and just after the downpour. Jackson received only 0.01 inches of rain that day.
Cape Girardeau has made improvements, but a serious storm still stops traffic.
In 2004, the city and federal governments completed a $40 million stormwater and flood-control project that included widening the Cape LaCroix Creek/Walker Branch runoff areas. On Friday, the water drained the way it was supposed to, just not quickly enough to prevent flooding, said officials.
"The channel there still had plenty of capacity, but nothing is designed to handle that level of rain at that speed," said city manager Doug Leslie. "We're going to be looking at the situation to determine what worked and what didn't at Cape LaCroix and Ramsey Creek, but there isn't much you can do to make water flow to those areas faster than it did."
Leslie said the storm was highly concentrated south of Broadway and west of West End Boulevard, causing rain to "stack up" in lower level areas. "That quadrant of the city caught the brunt of the flow," he said.
Stretches of Bloomfield Road, Mount Auburn Road and the Town Plaza parking lot were all under 1 to 2 feet of water.
Knudtson said he is not pleased with the drainage capacity but said it's the best the city can do without spending a significant amount of money. "We are clearly not equipped to handle that amount of rain, and that's not a revelation. We've been acutely aware of the deficiencies of our stormwater system," said Knudtson.
He pointed to a stormwater utility fee that voters rejected in 2003. It would have generated $730,000 per year. It was one of four ballot initiatives voters rejected. "On that ballot, really that was the initiative with the most merit," he said.
Knudtson also said the city is working with local developers on preventive measures that would increase the retention capacity of the Ramsey Creek Branch at the southwest end of the city. He said another top priority is to work with MoDOT to ensure I-55 avoids flooding in the future. "On Friday we had water across I-55, and that's a monumental event when it takes place," Knudtson said.
Public works director Tim Gramling said the storm was a rare event. "You'll hear in engineering they talk about a 100-year storm or a 50-year storm. It's kind of like a Richter scale measurement. I don't know what this rainfall was, but it was up there in the high numbers. To get that much rain in that little time is not typical," he said.
Gramling said public works crews were deployed as soon the rain began and that no sections of road were closed for more than one hour. "In that situation the only thing to do is deal with the aftermath and try to keep people off of the most severely flooded streets," he said.
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