Elm Road GS Water Intake Tunnel

Providing over two-billion gallons of cooling water per day

Kenny/Shea Joint Venture WePower, LLC (Owner) | United States | 2004-2008

27’-4” diameter of primarily unlined tunnel beneath Lake Michigan

Peak daily capacity of 2.2 billion gallons of cooling water


  • The Elm Road generating station (ERGS) needed a cleaner, more efficient system of cooling technology.


  • The ERGS Cooling Water Intake System was constructed by Kenny/Shea JV.
  • It consists of a lake-water intake tunnel excavated in rock and is 9,226-foot long; 27’-4” in diameter.
  • Approximately 2,000 feet of the tunnel is lined to a finished diameter of 25 feet.
  • The new water intake tunnel can supply a total of 2.2 billion gallons per day of cooling water to the existing Oak Creek and new Elm Road power plants.


  • This design-build contract combined drill-and-blast and tunnel-boring machine (TBM) operations using main beam gripper TBM and rock-support selection based on the geotechnical-baseline reporting of rock mass classifications.
  • The dike wall structure was approximately 250-feet long and contained nine gates to provide cooling water under emergency tunnel bypass conditions.
  • Difficult marine construction involved dredging, cofferdam construction, and underwater work while maintaining a cooling water supply to the existing Oak Creek Power Plant (OCPP).
  • A sunken caisson construction was used for on-shore mining and OCPP shafts.
  • After completing tunnel mining, the TBM machine was disassembled underneath Lake Michigan and carried in pieces back to beginning of the tunnel for removal.

Project Numbers

Project cost: US$105 million


This project was delivered under the Hatch Mott MacDonald JV.


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