Lower Meramec Tunnel Project

The 6.8-mile-long tunnel project — the largest ever for Metropolitan St. Louis Sewer District (MSD) — will improve water quality within the Meramec River watershed and help ensure regulatory compliance.


  • Missouri, USA

Project Status

  • Construction Start, January 2021
Tunnel Depth
286 feet 286 feet
Tunnel Diameter
12 feet 12 feet
Tunnel Length
6.8 miles 6.8 miles