Plans to develop the Arkansas River could threaten Tulsa's storm sewer system. Some say it's possible the water will travel backwards through the pipes, impacting the neighborhoods around the river.
If the river level rises, because it's dammed up and there's a flood, water can go from the river into storm sewer pipes. There's also a question about pipes that drain into the river being washed away if they're constantly underwater.
The Arkansas River is the drain for much of Tulsa's storm sewer system. It's lined with pipes that dump rain water into the river.
There are 51 pipe outlets inside the city limits, and while some are small, some are gigantic. And they all have to be evaluated as part of the river development plan.
That was the focus Thursday for the river development task force, which is charged with putting water in the river, but also with making sure it doesn't go anywhere else.
G.T. Bynum, with the Tulsa City Council said, "We want to make sure if we're changing the elevation of the water in the river, we're not affecting the storm sewer system and reducing its ability to drain in any way."
Neighborhoods all over Tulsa have storm drains that eventually connect to the Arkansas. They help drain localized flooding, but a major flood on the Arkansas could reverse the flow in some situations.
In the 1986 flood, some houses were flooded with river water from the sewer system. Now there are pumps to help control that, but it's still a concern during a major flood.
Paul Zachary with the City of Tulsa, said, "This could have water in the pipes all the way back to inlet structures. So if you opened up the manhole you would see water in it, and that's the ones we want to take a look at.
The city's engineering division is examining every outlet. Some have gates to prevent backflow, some don't. The biggest threat, the city believes, is that high water will wash away the pipes in the river.
"Anytime you have something and then you saturate the soil of the headwalls and it will drop, so we're going to anchor them so the pipes don't fall off," Zachary said.
The people planning the river want to make sure that doesn't happen, because they have been assured another flood will come, eventually.
"Tulsa is always at risk of a flood, but our greatest risk is because of releases from Keystone dam, not because of putting dams along the way," Bynum said.
The storm sewers flooding parts of the city would only happen during a rare flood like the one from 1986.