Maline Creek Combined Sewer Overflow (CSO)


St. Louis, Missouri


Secant Piles

subsurface conditions:

Several layers of soft clay with a sand and silt layer in between with groundwater approximately 10 feet from the surface at both sites, with  rock consisting of several feet of weathered bedrock above limestone

size and solutions:

Two secant pile structures: one shaft of 78 piles to depths between 40 to 50 feet and a second braced support of excavation structure of 114 piles to a depth of 48 feet.


Owner: Metropolitan St. Louis Sewer District’s Project Clear
General Contractor: SAK-Goodwin JV
Engineer: Jacobs Engineering Group

project snapshot:

The Maline Creek CSO Storage Facility is a part of mega-CSO program Project Clear. Nicholson quickly and successfully constructed two well-formed and water-tight secant pile structures that provided temporary earth support and groundwater cutoff for a large shaft and a large support of excavation box. Instead of going the traditional route, the Cased Continuous Flight Auger (Cased CFA) method used special equipment so the pipe could be drilled in one single stroke without having to remove the auger. Thorough concrete testing was done throughout the project to verify and confirm the flowability, stability and slump characteristics.

Maline Creek Combined Sewer Overflow (CSO)