Cedar Rapids’ Thursday night storm nothing like June 2014

CEDAR RAPIDS - Thursday night wasn't like a night last year in late June.

Jon Durst, the city's sewer superintendent, on Friday morning said Thursday evening's rainfall in the Cedar Rapids metro area reached 2.2 inches in the hour between 8:45 p.m. and 9:45 p.m., an intensity level significantly below the 4.28 inches in a single hour in late June 2014 that caused widespread flash flood damage in the city.

On Friday, Durst said the city's Public Works Department had received fewer than a dozen calls from residents about water in basements or sanitary-sewer backups, compared with 322 similar calls within a couple of days of last year's deluge.

He characterized the intensity of the Thursday evening storm as a 10-year event, or something the city has a 10 percent chance of seeing in any given year. Last year, the event was a 1,000-year event, or something the city has a 0.1 percent chance of seeing in a year, he said.

Durst said the city's storm sewer lines are designed to handle a storm of smaller intensity than the Thursday evening one - one that occurs every five years. But the city's overall system, which includes overland water runoff routes such as streets, is designed to handle a more severe, 100-year storm, and, as a result, the city's system was able to handle Thursday's 10-year storm.

Even so, he said the city experienced some areas of localized street flooding.

Greg Buelow, the city's public safety spokesman, said water in the street trapped some motorists in cars, requiring firefighters to help motorists in 12 spots get from their vehicles to safety. Nine other vehicles were stranded in water, but the motorists got out by themselves, he said.

Durst said city crews put out pumps at three spots to draw stormwater out of the sanitary sewer system - at 39th Street NE and Lennox Avenue NE; 17th Street SW and 10th Avenue SW; and 15th Street NW and B Avenue NW.

A pump also was used at Penn Avenue NW and Ellis Boulevard NW and First Street NW to help the storm sewer system.

He said city crews also monitored the 1500 blocks of A and B avenues NE, which were hit hard last June, and no similar flooding was occurring.

He said the city's storm sewer and sanitary sewer systems should be able to handle a storm like Thursday evening's should it occur in the days ahead.

Next door in Marion, the heavy rain caused flash flooding on Indian Creek, forcing the city to close Thomas Park and Boyson Trail.

Cedar Rapids City Council member Scott Olson, chairman of the Infrastructure Committee, was eager Friday to see how Thursday's storm compared with the storm in June 2014.

A year ago, the storm at the end of June damaged about 50 home foundations, knocked down trees and prompted the 322 calls about sewer backups or home flooding. A teenager died when he was washed into a storm sewer.

In the aftermath of last summer's storm, the city identified about $50 million of needed capital improvements for its storm and sanitary sewer systems in about 50 areas, Olson said. He said the city is completing a master plan so it can prioritize the work.

'A lot of this is stuff from years and years ago that was studied but never done,” Olson said. 'And so this will be the first comprehensive study that puts everything into one package and then (recommends) different methods of financing the work. … So we can go back and start attacking all the old issues and the new issues and see if we can make a difference.”

Durst said some projects already have begun.

As for the Cedar River, Durst said Thursday's rain caused the river level to rise from 5 to 7 feet, still well below the minor flooding level of 12 feet and far from the 31.12 level of the historic flood of 2008.

He said many of the tributaries that flow into the Cedar River are full and now flowing into the river, but that water should be through the city before peak levels from north in the river's watershed arrive in the city, he said.

The National Weather Service said Friday the river level would rise to 7.6 feet before it falls.