The City Council has retained professional consultants to help secure federal funds that would finance badly need flood prevention measures in Chickasha.
For more than a century the town “has grappled with severe flooding issues” that have caused significant damage to property and infrastructure,” Community Development Director Rachel Bernish noted. “Despite numerous studies and engineering assessments dating back to 1978 … we have yet to implement a comprehensive solution.”
The Building Resilient Infrastructure and Communities grant program administered by the Federal Emergency Management Agency “presents a unique opportunity to secure substantial funding for our flood mitigation efforts,” Bernish told the City Council.
A BRIC grant could provide up to $20 million, “with a potential for more based on final scope and FEMA evaluation,” she wrote.
The council picked Meshek & Associates, “the only firm in Oklahoma to have successfully secured a competitive BRIC grant,” to be its “potential partner for this crucial initiative.” The company has offices in Oklahoma City and Tulsa.
A Master Service Agreement the council approved with Meshek provides for “a flexible, phased approach” to the project. Task Order 1 will include:
• Review and update Chickasha’s existing drainage study.
• Develop a comprehensive BRIC grant application, which must be submitted by Dec. 1, 2025, the council was told at its Oct. 7 meeting.
• Submit a Hazard Mitigation Grant Program application “to help fund this initial phase.”
The city has already submitted a Notice of Intent to Oklahoma Emergency Management for an HMGP grant, which would require the city to provide 25% in matching funds that would be paid “from an existing city account designated for flood and drainage projects,” Bernish said.
Approval of the Master Service Agreement and Task Order 1 “represents a critical first step toward addressing our long-standing flooding issues,” Bernish wrote.
“We’ve kicked this can down the road long enough,” Vice Mayor Georgianne Hebblethwaite said in July. “We need to move forward.”
“Flooding in Chickasha is beyond the city’s ability to address alone,” City Manager Keith Johnson said.
More than one-third of the community is located in a “special flood hazard area,” which results in areas and intersections being routinely closed due to anticipated flooding.
One Chickasha family “would have to raise their home 3 feet to remodel it,” Fire Chief Tony Samaniego said previously. But if the city applied for and received the FEMA grant, and flood prevention measures were implemented, that would get the family out of the flood zone and they wouldn’t have to elevate their house, he said.
Multiple flood studies performed in 46 years Multiple studies about flooding in the city have been conducted in the past 46 years, records show.
• In 2015, Chisholm Trail Consulting performed a Downtown Flood Mitigation Study, which identified the stream names that convey storm water runoff in town. That study focused on the removal of bridges in order to mitigate flooding and was primarily a Hydrologic Engineering Center ~ River Analysis System study.
• FEMA conducted flood insurance studies in 1991, 1993, and again in 2012. Those studies were used to determine peak discharges and floodplains in the city.
• Other studies were completed by Smith Roberts Baldischwiler engineers, surveyors and planners, of Oklahoma City, in 2007 (Line Creek east of Fourth Street); C.H. Guernsey in 1995 (Line Creek); Landmark Engineering in 1992 (Congo Creek); HTB and the U.S. Army Corps of Engineers in 1984; and Southwest Engineering (drainage master plan) in 1978.
• Most recently, in 2019-20 SRB prepared a comprehensive “Master Drainage Study” in a three-ring binder that was two and one-half inches thick and replete with data, maps, hydrologic and hydraulic analyses, and myriad statistics about Chickasha.
The master drainage study cost $300,000 and was financed from a 75/25 cost-share FEMA grant from the Oklahoma State Hazard Mitigation program. FEMA paid $225,000 and the City of Chickasha contributed $75,000.
History of flooding from sustained rains Chickasha – county seat of Grady County and home of the University of Science and Arts of Oklahoma – is an area of roughly 22 square miles and has a population of approximately 16,500, according to the Census Bureau.
Localized flooding “has been attributed to the condition and inefficiency of the city’s storm sewer system,” SRB wrote. An example of that was the intersection of 14th Street and Missouri Avenue, which was rebuilt last year at a cost of almost $288,000 after the four-way junction was heavily damaged by runoff rainwater that overloaded the drains during a storm May 13, 2023.
SRB developed assessments for 19 watersheds that contribute stormwater runoff which flows through Chickasha to the Washita River. Upstream retention ponds would probably be a major feature of a comprehensive flood prevention program, the City Council was told on Oct. 7.
Flooding blamed on multiple issues Several issues were determined as the cause of stream flooding and erosion at Line and Congo creeks.
• Over time, through construction of the city’s storm sewer system, urbanized flow that historically was conveyed to Congo Creek has been rerouted to Line Creek. In the same way, an unnamed tributary that historically was conveyed directly to the Washita River instead now flows into Line Creek.
Also, other tributaries have been broken due to urbanization, and the time of concentration has decreased for the basins, resulting in runoff getting into creeks and streams faster.
• Bridge sizing along Line and Congo creeks is inconsistent. For example, 11 of 13 steel-reinforced concrete box bridges that Congo Creek passes through in Chickasha are undersized based on hydraulic calculations.
• Channel storage is insufficient and channel slopes do not convey flow rates efficiently.