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2018 Flooding: A Look Back, A Look Ahead

The extreme nature of the June 30, 2018 flash flood showed City officials exactly where problems exist in our storm sewer system. The City responded by nearly tripling the rate of construction projects with a plan to invest more than $145 million over the next six years.

June 30, 2018 brought a torrential downpour in Des Moines. In many neighborhoods, particularly in the north side of town, it was a record-setting amount of rainfall in a very short period of time. It absolutely overwhelmed the ability of the storm sewer system to handle that amount of water.

Forecasts predicted two inches of rain, but everything changed when the storm stalled over Des Moines. Some areas of the city were hit with 8-10 inches of rain in just 2-3 hours. A historic flash flood was underway.

“We’re a pretty strong, great, resilient community,” said Chris Coleman, At-Large City Council Member. “But on June 30th, the climate won and we had to figure out a way to get around it.”

For the first 12 hours, Des Moines Police answered 1,669 emergency calls, or 139 calls per hour. The Des Moines Fire Department responded to 170 calls, including 71 emergency rescue and assist calls.

“We’ve designed storm sewers to handle once-in-a-lifetime kind of events, and this was once in three lifetimes,” explained Jonathan Gano, director of Des Moines Public Works. “That is not something that any infrastructure is ever designed for.”

ASSESSING THE DAMAGE

We ended up with more than 1,800 homes that reported negative impacts from the flash flood, including minor basement flooding to outright destruction of the home.

In the immediate weeks following the flash flood, the City of Des Moines offered to use local dollars to purchase just short of 100 homes that were overcome with large quantities of water. Being able to use local dollars meant the City could provide financial assistance to move families on to new homes before any repairs or personal investment was made to repair the home to a habitable state.

It was astounding the amount of garbage the flash flood created. All around the city, people were disposing of damaged property including couches, fridges, carpet, drywall and so on.

The stormwater experience in some of Des Moines’ neighborhoods is very different today than it was when those neighborhoods were built in the 1930s-1950s.

Luckily the water dissipated quickly, but the pattern of problems the city has with it storm water system was made obvious to City officials. The flood response showed the City exactly where problems exist, and being able to move homes out of the major escape paths for stormwater has been helpful.

“There were issues that we could solve that we had never seen before because we had never had a night like that,” explained Coleman. “We need bigger sewers, we need to tear up our streets and we need to spend the money that’s necessary. It’s all for one and one for all now that this is a problem we’re going to solve.”

BUILDING FOR THE FUTURE

2019 CIP Storm Sewer Index MapThe City currently is responsible for maintaining an aging stormwater infrastructure that includes 490 miles of storm sewers, 35 detention/retention basins, 32 storm pump stations and 16 miles of levees.

The City is looking at spending over $145 million over the next six years on stormwater infrastructure improvements alone. For comparison, the City has spent $80 million in the past 10 years on stormwater projects.

This means the City is pretty much tripling the rate of projects that will help keep homes safe from flash flooding. What was already a historic increase in investment by the beginning of 2018 became and even faster, accelerated plan after the flash flooding in the middle of 2018.

For example, we’re continuing forward with the plan to improve the Closes Creek Watershed (primarily in the Beaverdale neighborhood), including extensive work to replace sections of old storm sewer under Maquoketa Drive that are currently made of wood.

We’re also starting work in the area of 47th and Holcomb to install large sewer boxes that will collect and store water underground to relieve neighbors from flooded streets while slowing the release of stormwater that makes it way through the system.

TAKE ACTION

While you’re likely not planning to personally install a large, expensive storm sewer on your property, every single property in town has rainfall that lands on it.

There is always an opportunity to capture some of that water on one’s own property before it reaches the storm sewer. From rain barrels to rain gardens, you’ve got options that will not only improve your home, but reduce the risk of flooding for your neighbors downstream.

Stormwater Best Management Practices Program

The City is currently offering the Stormwater Best Management Practices program that will reimburse property owners 50% of the cost (up to $2,000) for qualified work that reduces stormwater runoff.

A great example is Soil Quality Restoration (SQR), which is a simple process that includes aerating your yard and adding extra compost to make your yard healthier and greener. The process turns your yard into more of a sponge so that it can hold rainwater that lands on it and release it back to the environment at a much slower rate.