St. Louis, Mo., hides four miles of River Des Peres in tunnels beneath Forest Park
(UI) — Deep beneath Forest Park lies a hidden system of tunnels carrying the River Des Peres, which is nearly half of the river’s roughly 10-mile course, according to Fox 2 Now. The enclosure was originally implemented to mask the foul conditions of the open stream during the early 1900s as St. Louis expanded.
Today, that system remains vital. The tunnels carry mixed wastewater and stormwater to Lemay Treatment Plant through what’s known as the Forest Park Junction Chain, where flows from multiple lines converge, Fox 2 Now reports.
MSD officials caution that this is not a navigable river. They warn of dangerous sewer gases and rising water levels during storms. Modern tunnel work now relies on massive TBMs—making the hand-dug, 29-by-23-foot tunnels constructed over a century ago a remarkable engineering achievement.
To bolster capacity, MSD plans a new network of 15–16 miles of deeper tunnels - up to 250 feet underground - to add roughly 300 million gallons of capacity. That project is scheduled for completion by the late 2030s.
Related News
From Archive
- OSHA issues 16 citations following fatal sewer confined space incident
- 27 pipeline safety violations tied to deadly Pa. chocolate factory explosion
- Contractor gas line strike triggers home explosion in Missouri
- LA recovery reports call for $650 million power line burial, major utility upgrades in Pacific Palisades
- Comprehensive microtrenching FAQ: Key insights on the Vermeer MTR516 microtrencher
- T-Mobile to expand fiber broadband infrastructure footprint with $4.9 billion Metronet acquisition
- First tunnel boring machines complete testing for Hudson Tunnel Project
- NWPX grows water infrastructure portfolio with Colorado precast facility
- Cityside launches $100 million fiber build in Corona, Calif.
- FiberLight to build 1,400-mile West Texas dark fiber network in $350 million expansion

Comments