Water Main Hot Tap Critical to O’Hare Runway Project

A critical water main relocation was the enabling project for the $6.6 billion O'Hare International Airport modernization project in Chicago, Illinois.  The 90-inch pressurized water main lay directly under the proposed path of the runway expansion.  The team of Stanley Consultants and T.D. Williamson was selected to stabilize, hot tap, and divert the water main while pipeline was being constructed around the proposed runway.

Stanley Consultants designed a thrust block restraining collar that absorbed the internal and external forces, transferring all loads from the hot tap and the pressurized pipe into the ground by use of 10 large diameter caissons tied together with a concrete cradle and steel tube framing.  Once the pipe was tapped and the bypass was operating, the new 90-inch water main was connected and switched over without incident.

The 25-year-old water main served O'Hare.  Project complications could have grounded hundreds of flights.  Careful engineering and design services resulted in no water service disruptions.  The pipe size and design water pressure within the pipe, combined with the social and economic impacts made this a one-of-a-kind project.  Using the hot tap process over the next best alternative resulted in a savings of $80 million.