|The public got a sneak peek recently at the dam designs a group of engineers are working on to estimate the costs of building several low-water dams on the Arkansas River.
While their full report isn’t coming until the end of April, the City Council’s Arkansas River Infrastructure Task Force got an update on the design plans, including the type of dam the engineers are pitching:
The designs all call for a system of steel gates on hinges — called an Obermeyer Gate — that rise vertically when a large rubber bladder at its base is inflated.
The hinges connect the steel gate to the foundation of the dam, forming a wall when the downstream bladder fills and lowering the gate’s profile when the bladder deflates.
“This is really the only (option) that you could have in a river situation like this because you want to have water there, but then when you have floods, you want that dam structures to have zero or minimal impact so the gates have to be able to go down,” Murry Fleming, vice president of CH2M Hill, told task force members.
The gates would consist of crest gates, which are only a few feet tall and stand on top of a permanent dam wall, and full-height gates that could be lowered to release debris and sand.
Councilor G.T. Bynum, who is leading the task force, said the Obermeyer Gate design would be used on all proposed dams, including the rehab of Zink Dam, which would be rebuilt from its foundation.
The bladder-gate design is an economical option that requires very little maintenance compared to the hydraulic mechanisms that faltered on the current Zink Dam, Bynum said.
Fleming’s report did not include cost, which is the focus of the final report, but he said the inflatable dams were the most cost-effective option.
Bynum and Fleming also focused on extinguishing thoughts that the bladders used to raise the plates would be vulnerable to vandalism.
“People think of them as balloons that someone is going to come out and shoot and all the gates are going to fall down,” Bynum said. “It’s more like a tire.”
Fleming said the rubber bladders are made of a reinforced tire-like rubber that stands up to abuse.
But even if the bladders do get punctured in their 30-year-plus lifespan, patching them or replacing them is a relatively cost-efficient process.
Raising the plates only takes about 20 pounds per square inch of pressure, he said.
“It’s not like a blowout in a tire,” Fleming said. “It’s a slow leak. … You would have a repair just like a repair on a radial tire.”
Jarrel Wade 918-581-8367