Between a Rock and a Hard Place! A Creative Underground Solution to Very Challenging Surface Conditions

This paper will discuss the approach the project team took to implement the design, procurement, and construction of the 72-in. Elm Fork Pipeline in a heavily urbanized area as well as the use of a deep tunnel method to avoid many of the surface challenges identified during the design phase. The new 5-mi 72-in. water transmission line will provide additional capacity and redundancy to an existing 54/66-in. Prestressed Concrete Cylinder Pipe (PCCP) line between two major Dallas Water Utilities' (DWU) Water Treatment Plants (Bachman and Elm Fork) built in the 1950s. This paper will also share some of the design aspects to facilitate pipe operation and maintenance for deep tunnel installation and discuss several of the lessons learned during the tunnel construction and pipe installation inside the tunnel for the first phase of the project, leading to the adjustment of the design approach during construction.