Davenport flood mitigation projects set to start in 2023

Davenport flood mitigation projects set to start in 2023
Davenport flood mitigation projects set to start in 2023(MGN)
Published: Jan. 21, 2023 at 9:38 AM CST
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DAVENPORT, Iowa (AP) — In late 2023, residents and business owners will see some of the first projects of Davenport’s flood mitigation plan under construction.

The first phase of Davenport’s $165 million plan aims to address floodwaters that surge up from the ground because of backed up storm sewer systems.

And two projects are funded and will go out to bid and construction in late 2023, according to Assistant Public Works Director Clay Merritt.

The Quad-City Times reports that after the river crested at a record 22.7 feet in 2019, breaking temporary HESCO barriers and causing upwards of $30 million in lost revenue and damages, businesses and residents clamored for a more permanent solution to address surging floodwaters.

For decades, Davenport residents have resisted a flood-wall, for concerns it would impede resident access to and views of the mighty Mississippi.

But a flood study done by engineering company HR Green laid out a lengthy list of projects that by the end of a three-phase plan aims to keep River Drive open at a flood stage of 22 feet that includes updating storm sewer infrastructure below ground, raising sections of roadways, and starting a cost-share program between the city and business owners to flood-proof buildings.

Most recently, in December, federal lawmakers passed a $1.7 trillion bill to fund the government. Included in it were earmarks for projects in legislator’s districts. Although Davenport’s representative, Republican Mariannette Miller-Meeks voted against the final bill along with most of her Republican colleagues in December, 12 community projects in the 2nd District made it into the final bill — including $1.265 million for Davenport’s flood mitigation efforts.

That funding will go toward storm sewer improvements at the intersection of River Drive and Marquette Street for minor flooding events.

The project, which Merritt said was likely to begin construction late fall or early winter, would install future bypass storm sewer and backflow prevention to halt river water from backing up into the intersection near River Stage 14.5 feet. Instead, the project would keep the intersection un-flooded until 18 feet.

Previously, Merritt said the the city had to use labor and some temporary pumps to try to keep the intersection open to travel, efforts that were made much more difficult when it started raining.

“That’ll save us a substantial amount of time, effort, labor, and money when we have those smaller-level floods specifically in that area,” Merritt said.

City council approved engineering for the project in August, 2022.

Another project that is on the same timetable as the Marquette-River Drive intersection, is a $4 million ARPA-funded storm sewer improvement that aim to keep E. River Drive access through intersections of 3rd and 4th Streets up to a flood stage of 22 feet. Currently, it closes at about 17.5 feet. The plan would also install backflow prevention on the local storm sewer system, and a new storm sewer connection will be constructed to separate existing intakes below Flood Stage 22 between Carey and Third streets.

“In 2024, you will certainly start seeing some of those benefits as these construction projects that will be underway this year are completed,” Merritt said.

They are two small parts of the flood mitigation plan, which HR Green estimated to cost more than $165 million.

City staff and Mayor Mike Matson Davenport is always searching for more federal, state, and local funding sources.

Phases two and three of the plan, that involve construction of more permanent flood-fighting measures such as walls, berms, and permanent pumping stations, total about $140 million.

The city is preparing an application for a federal RAISE grant for a second year — the federal program awarded East Moline a $23.7 million grant to promote connectivity and accessibility in economic hot spots in the city.

Merritt said the city advanced several rounds in the grant process, said staff believes the city has “a really strong application.”

Last year, the city applied for a $15.9 million grant through the RAISE program for road raises at four intersections and other improvements with a goal to maintain access to River Drive until river reaches 17.5 feet with little to no staff response and ensure interstate access to Centennial and Government Bridges when the Mississippi reaches above 22 feet.

Also underway are flood protections for the Water Pollution and Control Plant, which serves more than 139,000 people according to the city. In September, the city received a nearly $10 million grant from the Department of Commerce’s Economic Development Administration.

The city has also completed some berm restorations at Blackhawk Creek.

Merritt said several of the projects require extensive permitting and engineering, which is why they estimated the late winter construction.

“The flood plan itself was approved last year and 2022 was a lot of setting the groundwork and laying the foundation for engineering work to occur so that in 2023, we can start following up on pretty substantial amount of construction jobs,” Merritt said.

The National Weather Service’s current flood forecasting predicts a low chance of flooding in the Quad-Cities through at least March due to, in part, unseasonably warm temperatures. Updated spring flood forecasting will be released in early February.

Mark Wilson, a service hydrologist for the National Weather Service’s Quad Cities location, said there’s several factors that feed into weather forecast calculations.

Flood forecasters look at northern states’ depth of frozen ground, snow pack, soil moisture level, and river stage.

“For frost, that tells us how deep the ground is frozen. That’s important for us because if we have snow on top of the frozen ground, when that snow melts out that water’s not going to soak into the ground easily,” Wilson said. “It will become what we call runoff and it will enter the streams quicker than what we would like. It would mimic like a large rain runoff.”

And if the warm temperatures continue, it’s likely the Upper Mississippi’s soil can absorb the waters.

“It’s not looking particularly cold for the rest of the winter,” Wilson said. “But we are maybe near average or slightly above average precipitation where we had had some — I think about two thirds of the Upper Mississippi Basin either at abnormally dry or higher drought stages. So, should be enough capacity to hold in in in that water inside the river channel and have it be absorbed into the soil.”