Waller Creek tunnel to relieve flooding in city’s core

AUSTIN (KXAN) — The kind of watery mess created by Thursday night’s storm in the 28-acre flood plain of Waller Creek should soon be a thing of the past.

Downtown Austin’s $106 million tunnel project will be operational by the end of the year, on time and on budget. Including surface projects, the total cost hovers near $147 million.

The tunnel runs a little more than a mile, curving from 12th Street down to Lady Bird Lake. With three intake shafts, the tunnel will be expected to handle the severest of storms, like the 1915 flood that killed 35 people.

“Should we get a hundred year storm the tunnel is designed to convey that amount of flow through the tunnel, under downtown and safely past to Lady Bird Lake,” said Joe Pantalion, deputy director of Austin’s Watershed Protection Department.

Such a storm would mean 10 inches of rain within 24 hours, creating a flood wall of 3.7 million gallons of water per minute.

Best of all the tunnel operates naturally, without mechanisms, electronics or the chance of human error.

“The way the engineers designed it is to work by simple gravity, just like your bathtub drain,” Pantalion explains. There are even mechanics involved to clear the debris screens located by the drain shafts at 12th, 8th and 4th streets.

The flood plain protection covers one million square feet, 42 current buildings and 12 roads in the area, running from 12th Street to the lake, and from Red River east to Interstate 35.

And as a bonus, the perpetually filled underground tunnel will always maintain water in Waller Creek, making for better aesthetics, attractive to business, good for the ecosystem and eliminate that dry creek bed stench that occasionally arises in the dry summer months.

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