What can the city of Derby do about flooding issues from Spring Creek, now and long into the future?
That, in summary, is what a comprehensive report commissioned by the city is all about. Experts from the firm of Wood Environmental and Infrastructure Solutions were on hand at the Nov. 26 City Council meeting to present their findings and answer questions about the report, called the Spring Creek Flooding Improvement Study.
The study cost $120,000. Dan Squires, director of planning and engineering, said it was money well spent.
“We’ve never had this detailed of a study,” he said. “I think we got exactly what we were looking for.”
Squires said city officials went into the process not knowing if they could do anything cost-effective, but believed that they likely needed to take a look.
In his 17 years with the city, Squires said staff had evaluated solutions, but never have been able to run modeling like this one has, and seeking outside help was the only answer.
“It wouldn’t be cost effective for us to do this anyway, just for the purchasing and licensing of all the models, not to mention the expertise,” he said.
The study’s time-extensive aspect was to build flooding models, then come up with ideas and improvements, put those into the models and then see how they work.
Action is already being taken on two projects as Squires received preliminary data during the budget process.
“The city manager is adamant that if we do a study, we are going to take action,” he said.
Two projects already approved
The design and construction of the two projects were included in the Capital Improvement Plan approved by the City Council in August. Design of the first project begins in 2020.
In all, the city’s 2020-2024 CIP calls for an estimated expense of $2.1 million of stormwater management facilities projects.
Flooding is one of those situations that residents don’t think much about when it isn’t happening, Squires said.
His department received a lot of flooding comments in 2016 during that year’s major stormwater events, but Squires said that just because this hasn’t been a bad year for flooding that there’s no cause for concern.
Eric Broce, a professional engineer with Wood Environmental and who worked on the study, agreed.
“Stormwater is tough from a public viewpoint,” he said. “Water and sewer is something people use every day, but stormwater is something people only care about when it’s flooding.”
The common feedback, he said, is that people ask: “Why aren’t you spending money on flooding when it’s underway?” Then, when it’s not flooding, they question the expenditures.
But stormwater is “an animal,” Broce said, and preparation is the only answer for it.
Broce and Squires pointed out that water doesn’t care or “respect” city or county lines, fences or any other man-made boundary and will go where it wants to go, unless forcefully redirected.
County has done its own study
John Covey, also an engineer with Wood, said Derby’s study was quite sophisticated and beyond what is normally done. The firm used a lot of historical data in its study, including the events from 2016, and worked to attempt to forecast what could happen in the future and how the water might move and the damage that it would cause.
Sedgwick County also has done its own study on the Spring Creek Basin, which was presented in 2014. That study evaluated the entire basin looking at numerous issues including flooding, stormwater quality and erosion.
As Spring Creek runs through Derby, the city took part in the study.
Improvements to address the issues from that study added up to about $200 million. However, that funding has been a roadblock for action steps as county officials have not designated funding to undertake study recommendations.
Last year, the city issued a contract with Wood Environmental to examine issues within Derby.
The study emphasized protection of structures subject to flooding, and street flooding also was evaluated. According to Squires, there are places where both structure and street flooding could be reduced.
City officials wanted to see if they could identify any “cost-effective solutions” that the city could undertake without the county’s participation. That was successful, he said; however, “in other areas, the cost to alleviate flooding was found to be more substantial and difficult to fund at the local level.”