Deer Creek Sanitary Tunnel And Pump Station —St. Louis, MO
Client
- Metropolitan St. Louis Sewer District (MSD)
Project Value 
$828 Million
Market
Energy And Environment, Tunneling, Water And Wastewater
Services
Engineering, Program/Construction Management (PM/CM)
We have been working with the Metropolitan St. Louis Sewer District (MSD) since 2011 on the Deer Creek Sanitary System Program, and in 2016 design work was completed for the Deer Creek Sanitary Tunnel project. The contract was awarded to SAK Construction for $147.8M, and construction began in Fall 2017.
Features Of The Deer Creek Sanitary Tunnel And Pump Station
The tunnel is approximately 4 miles long with an inside diameter of 19 feet and is located 175 feet below the surface in solid rock in a highly urbanized area of St. Louis. It has the capacity to store more than 38 million gallons during wet-weather events. It will be pumped dry after high flows have subsided, and the downstream treatment plant has available capacity.
In addition to the tunnel, SAK constructed eight shafts required to provide tunnel access for collection sewers and the pump station located at the downstream end of the tunnel. Diversion structures were designed to divert flow to the tunnel once the flow in the existing sanitary sewer system has reached a critical depth. Gates will be utilized to control the flow in the existing sewer and prevent sewer surcharging that could cause basement back-ups during wet weather rain events.
Mining of the tunnel was completed in only 11 months with a 22-foot diameter tunnel boring machine (TBM), maneuvering through 14 designed curves at a grade of 0.20% and arriving at the planned horizontal and vertical location.
In February 2020, the design of the Pump Station was finished, and construction began the following September by KCI Constructors at a cost of $29M. The pump station was designed to control the discharge rate from the tunnel, which will be limited due to downstream sewer capacity. Different pump types were evaluated to determine the most economical, reliable, and maintainable system. Work on this contract includes one wet well and two dry wells in shafts previously constructed by SAK, one wet well building, one dry well building, one effluent vault structure, and numerous site improvements.
Project Challenges And Completion
The project suffered a delay due to unexpected flooding in July 2022 when St. Louis received over 9” of rain in a 24-hour period. Substantial completion was met in April 2023, and the contractor is currently finalizing punch list items.
