Heavy rains bring up questions about Oklahoma's highway drainage systems

By Don Gammill

Published: September 8, 2008

Rainwater can be a blessing or a big problem.

When the runoff builds so quickly — as it does after a typical Oklahoma rain — it can play havoc with traffic.

Here is one area where the reader says an even bigger problem may be in the future.

There has been a serious storm water runoff drainage problem for decades in the southbound lane of Interstate 35 on both sides of the NE 36 overpass, especially on the south side of the overpass. The outside edge of the asphalt shoulder on the outside southbound lane is much higher than the outside lane, which means during rains the outside lane, rather than the shoulder, becomes the drainage ditch for runoff from the roadway and the embankment. This causes torrents of water to run down the outside lane toward the storm drain under the overpass even during moderate rains. Traffic slows, accidents happen, cars die from flooding and it's a hydroplaning hazard in light rains. The shoulders are higher because there are no concrete retaining walls to prevent the clay embankment from softening and flowing under the shoulders. Over the decades, this plastic flow of the clay embankment has raised the shoulder from the outside edge so that the shoulders now slope sharply towards the outside lane. The shoulders need to be ripped up and replaced with shoulders that slope AWAY from the outside lane. And, concrete retaining walls need to be installed to prevent the clay embankments from softening during wet conditions and again flowing under the new shoulders and raising them again in the future. Does the Oklahoma Department of Transportation have any plans to fix this decades-old problem? And if not, why not?

Terry, Edmond

Here's what Cole Hackett of the media and public relations division of the Transportation Department has to say:

"The area of I-35 at 36th Street that Terry is referring to is lower than the roadway north and south of it to allow runoff from heavy rains to be funneled quickly to the drainage system under the 36th Street overpass.

"The slope of the roadway is designed to funnel rain that falls on the roadway toward the shoulder, then downhill to the drains at 36th Street. In periods when heavy rains occur in a short period of time, puddling may occur since the water may not be able to run off the roadway quick enough to keep up with the large volume of rain that is falling.

"Also in times of heavy rain, the drainage system under the bridge may be unable to keep up with the large amount of water running to it, which may cause some water to back up onto the shoulder and the roadway at 36th Street. This excess is quickly drained once the rain slows.

"The shoulders and areas adjacent to the roadway are built up in a way to keep excess water from flowing onto the roadway from the shoulder.

"Currently, there are no projects scheduled to change the drainage in this area, but our crews inspect these drainage systems frequently to make sure they are working properly and to see if any changes need to be made.”

By the way ...

If you notice obstructions, such as tree limbs or piles of discarded items in a drainage ditch, or if the road appears to be crumbling near a runoff site, don't hesitate to report it. That might be a little problem soon to grow into a big one.

Enjoy your week and drive safely.

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