Elm Fork 72-inch Water Transmission Main Phase 1

Completed in 2024 by Southland Contracting, the Elm Fork 72-inch Water Transmission Main Phase 1 Project consisted of the construction of a 72-inch diameter water transmission main that will extend approximately 1.8 miles starting from the Elm Fork Water Treatment Plant to near where West Crosby Road passes beneath I-35 East Express in Carrollton, Texas. The original design involved the water main invert generally installed between 20 and 40 feet below the existing ground surface and extending mostly through alluvial deposits, with portions extending through weathered shale with artesian conditions. The original design was to be installed using a combination of cut-and-cover and microtunneling trenchless construction methods amidst a myriad of existing utilities and surface development features. However, upon award of the contract, Southland proposed an alternate design and construction approach, with the pipe lowered sufficiently to allow for construction using tunneling methods, and entirely located within the Eagle Ford shale bedrock. An engineering firm was contracted to assist with the redesign of the now deeper various shafts and now longer tunnel. The redesigned project now includes 8,575 linear feet of tunneling in total ranging in depth from 65 feet to 75 feet, two tail tunnels each at 40 linear feet, and five vertical shafts ranging in diameter from 18 to 35 feet. The tunnel is being excavated using a Southland manufactured single shield Tunnel Boring Machine (TBM) with a 118-inch excavated diameter and a steel shield with an outside diameter of 116 inches. The project also includes 186 linear feet of 92-inch diameter tunnel under the Dallas, Garland, & Northeastern Railroad & DART Light Rail at a depth of 30 feet.