City has identified $13.2 million of work to take on flash flooding

CEDAR RAPIDS - City project engineer Sandy Pumphrey told a public forum last night that the city has identified 18 different areas in the city that experienced damage from flash flooding in late June that might be helped by infrastructure improvements.

An estimate of the cost for the improvements is $13.2 million, he said, adding that the city's Public Works Department likely will include some of the projects in the capital improvement budget it recommends to the City Council in January.

Pumphrey said the city was studying where it can help to prevent future problems, but he said the city was not assuming liability for last summer's flash-flooding damage.

He provided a list of the 18 proposed projects to the council's Infrastructure Committee in a late Wednesday afternoon committee meeting.

At the meeting, Council member Scott Olson, the committee chairman, said it was important to have monthly updates so residents who had damage from the summer's flash flooding can see the city is trying to understand what happened and remedy it.

The project list consists of projects ranging in cost from $3,500 to $2.7 million. The least expensive project, culvert repair on 33rd Avenue Drive SW, is already funded as is a $110,000 project to add capacity to a sewer intake and to grade the ground to provide overland water flow at 16th Avenue SW and Edgewood Road SW. A $1.3 million project to build a berm and create an overland flow route at Cottage Grove Parkway SE is partially funded, according to the city's project list.

Pumphrey and others spoke to a small group last night at the Cedar Rapids Public Library in a flash-flood education event organized by neighborhood leaders.

Pumphrey said the city received 322 citizen calls about sewer backups and home flooding in the two weeks after the June 30 flash flood, which he said was prompted by 4.28 inches of rain in a short period of time. He called it a downpour expected to occur less often than once in 100 years.

He said the city, with the help of an engineering consultant, has identified 47 areas of flooding that qualify for engineering review. Of those, 18 may benefit from infrastructure improvements; 8 are still being studied; and 21 don't appear as if they will benefit from city involvement.

Some of the latter involve areas where homes or businesses are next to flood plains and are at risk of flooding and some had problems that can be remedied by neighbors themselves, he said.

The city has two sewer systems, a storm sewer system and a sanitary sewer system, and both can have problems when a deluge strikes, Pumphrey said.

The storm sewer system, he said, would need sewer pipes of 'ginormous” size to handle extraordinary rainfall, and so proper development has designed into it 'overland flow routes” such as streets and ditches to handle what a storm sewer can't. Some places, in older neighborhoods and in some newer ones in the city, don't have adequate overland routes, he said.

At the same time, Pumphrey said some houses in the city have sump pumps and foundation drains improperly tied directly into the sanitary-sewer system, which cause that sanitary system to be inundated and to back up into basements during heavy rain.