Did you know there’s a massive project happening under downtown Houston right now?

The drainage project is designed to prevent flooding of major streets and bayous.

HOUSTON — Right now, there is a massive drainage project happening beneath downtown Houston, and most drivers don’t even realize it’s there.  

Crews say it’s one of the most important steps before the I-45/I-69 rebuild, designed to be a solution to protect homes and businesses from flooding for decades to come. I got an exclusive first look at what’s happening underground. 

You may not notice it while driving near downtown, but crews are hard at work below the surface installing huge concrete boxes that will eventually carry millions of gallons of stormwater away from busy streets and businesses.

“They’ll be put underneath St. Emanuel, and that water will drain north,” said Danny Perez with the Texas Department of Transportation. “It’ll drain north from where we are now up to almost the edge of east downtown to this big detention pond that they’re building at Runnels Street and I-69.”

That detention pond will hold up to 76 million gallons of water.

“That’s the equivalent of 115 Olympic-sized swimming pools,” Perez said. “That water will stay there and drain into Buffalo Bayou more gradually, not at once. That’s what overflows the bayou.”

Each concrete box underground is about the size of a small garage stacked end to end beneath St. Emanuel Street to move floodwater faster and keep it out of Buffalo Bayou. 

To install the system, engineers had to dig as deep as 50 feet below the surface using tunneling machines that let them work under active streets and METRO rail lines without interrupting service.

“In some places you have to open the street,” Perez said. “We want to keep our rail running, so they went ahead, they dug underneath, connected on the bottom, and then put them underneath.”

The drainage work is expected to continue through 2028, and officials say it has to be finished before crews can rebuild the main lanes of I-45 and 69 through downtown. Doing it now means they won’t have to tear the same streets up twice. 

“It’s dusty. Maybe you’re detoured,” Perez said. “Understand that in the end it’s worth it, and it’s hard. A better drainage system, a better roadway system, a better way for you to move around.”

This part of the project will take another three years, but will bring solutions for potential flooding.  

Got a news tip or story idea? Email us at newstips@khou.com or call 713-521-4310 and include your name and the best way to reach you.