No-Dig Solution to Major Sewer Line in St. Louis

The Metropolitan St. Louis Sewer District (STLMSD) faced a problem familiar to many big city wastewater departments managing underground assets. A large (72-inch) sanitary sewer needed to be replaced with an even larger line to handle wet weather flows without experiencing sanitary sewer overflows (SSOs). In the years since initial installation, the above-ground area had become heavily developed making excavation a difficult choice. Additionally, concrete pipe would be subjected to microbiologically induced corrosion (MIC) requiring consideration of long-term protection against future corrosion. The problem was overcome by tunneling 5,000 linear feet of 96-inch reinforced concrete pipe fortified with an antimicrobial additive at depths 25 feet below the roads, parks and buildings located above it.