Sewer Tunnel Designed by WSP USA Will Be Longest Built in St. Louis

Seven-mile tunnel will improve water quality in Meramec River watershed, consolidate Metropolitan St. Louis Sewer District wastewater treatment plant operations.

©2018 WSP USA

Workers conduct a closed-circuit television inspection of the existing Baumgartner construction shaft, conducted on June 29, 2018.


The 6.8-mile-long Lower Meramec Tunnel stretches between Fenton to the North and Baumgartner in the south of St. Louis County, connecting to the Baumgartner Tunnel.