MSD’s massive Deer Creek wastewater tunnel is taking shape beneath St. Louis County

Apr 27, 2021

A massive wastewater tunnel is rounding into shape, more than 100 feet below a busy swath of St. Louis County.

The Metropolitan St. Louis Sewer District says the lining has been completed in the past several weeks on its $150 million Deer Creek Sanitary Tunnel project.

“The tunnel, itself, is basically done,” said Sean Stone, a spokesman for the utility.

Plenty more work is needed before the 4.3-mile tunnel begins operation. Still on track for its targeted completion in late 2022, the project features a tunnel 19 feet in diameter that stretches from Clayton to Interstate 44. Crews finished boring the tunnel early last year, churning through rock 150 to 250 feet below ground with a tunnel boring machine nicknamed “Mrs. Nancy.”

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