The floodwater has retreated, revealing new evidence of how so many downtown businesses were nearly destroyed.

The moment in which the HESCO barriers failed downtown Davenport on April 30 was captured on security video that has been viewed thousands of times. It appears the sand-filled wire cages simply collapsed against the weight of the water. But we couldn't be sure.

City officials, including Public Works Director Nicole Gleason, speculated the breach may have been caused by something else: maybe a failure of the roadway, such as a washout.

When representatives of the manufacturer, HESCO, came to town to investigate, they reached a similar conclusion.

"Following initial investigations, we believe that either the flood conditions caused the road surface beneath the barrier to give way or the river crested over the height of the barrier," according to a company statement.

Now that we can see it wasn't the roadway, we can conclude the city's temporary barrier was not enough to hold back the water. It wasn't strong enough. The HESCOs have done their job to protect downtown property for many years, but not this record-breaking year.

I asked Gleason this week whether city officials now are prepared to acknowledge a mistake was made in calculating the strength of the barrier. Her predecessor, who introduced Davenport to the HESCO barrier, has said the fortification was inadequate, and another row of cages should have been added to the line, so another layer could be stacked on top.

But Gleason insists the flood plan was followed. She said other factors led to the failure, not an inadequate flood-fighting height.

She pointed to several "anomalies" the city has explained during post-mortem meetings about the failed fight and what can be done better next time.

The first standout, she said, was the duration of the flood. The barriers had been in place for more than a month when the breach occurred. But the HESCO people said their barriers have been in floodwater for a year without failing.

Secondly: "Rail track raising (construction) during the flood and trains operating in floodwater above 18.5'." It's true the trains sometimes threw a wake when they passed through the high waters. I saw it myself. But wind has the same effect, which is why the barriers must be strong enough and high enough to withstand the action in the water. And the trains weren't running on the day of the breach.

The city's third anomaly is, "Volume/velocity of rain in the 48 hours leading up to the breach." That's no joke. We were hammered by rain for several days. That's why, on Saturday, this newspaper reported a warning by the National Weather Service, which also is the city's forecasting source.

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Three days before the barrier breach, meteorologist Andy Ervin said people should not let their guard down.

“We’re still dealing with rising water and the potential for rain," he said. "If you’re protecting for exactly 21 feet you have a few days to go out and protect yourself further if you have that ability.”

The city responded by throwing more sandbags atop the HESCO wall, but they didn't use the "pyramid" method that would have nearly doubled its height and bolstered its strength. Even though the updated forecast came on Saturday, the sandbags weren't added until Monday, which pokes a hole in the explanation Gleason provided this week.

"It was the most expeditious action that could be taken, as it requires an entire crew 12 hours to erect a complete line of barriers in good conditions with adequate space," she said of the decision to sandbag, rather than add HESCOs. "We had neither good conditions nor adequate space.

"... the working space for heavy equipment between the median, curb and buildings is not adequate for effectively/quickly placing and filling multiple rows of barriers."

They had several days to try.

The city's final anomaly in the flood of 2019 was "multiple top 10 crests in one flooding event."

Actually, the Mississippi achieved 20.6 feet on April 7, which was the ninth-highest crest. The other crest on May 2 brought two more feet of water, eclipsing the record from 1993.

But multiple floods in the same year isn't new. In fact, we had four floods in 2013, and the Flood of '93 took several jabs at us before and after setting a record.

Speaking of jabs, that's not what these observations are about. Nicole Gleason didn't want the barrier to break any more than the devastated nearby business owners wanted it to break.

And the city is doing the correct thing, having enlisted the help of the U.S. Army Corps of Engineers to help in a renewed evaluation of Davenport's overall flood-fighting strategy. That's what smart people do when something goes wrong; they rethink their practices.

My point is this: If you're going to give a complete and legitimate evaluation of all the variables at play to come up with a better plan, you simply must be prepared to recognize a mistake may have been made. It is unfortunate, under the circumstances, to have to warn you not to hold your breath.

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Contact Barb Ickes at 563-383-2316 or bickes@qctimes.com.