Lake Ouachita Water Supply Project
Michels Trenchless, Inc. completed a 2,569-foot-long, 60-inch tunnel beneath Blakely Mountain into Lake Ouachita to supply a new, much-needed source of clean water to the city of Hot Springs, AR to meet increased demand. Three different trenchless methods—Direct Pipe, microtunneling, and float and sink—comprised a creative approach that stemmed from Michels’ early involvement in the Design-Bid process and which also will provide significant operational cost savings over time.
The bore was completed using the Direct Pipe trenchless method of construction, making it the longest such installation completed at this diameter in North America. Additionally, Michels Trenchless installed 4,200 feet of 42-inch-diameter steel pipe with open cut installation methods and 510 feet of 56-inch-diameter Permalok steel pipe using single-pass microtunneling techniques at the Mazarn Creek Crossing site as well as 500 feet of concrete-lined 42-inch-diameter steel pipe by way of float-and-sink installation at the Lake Hamilton Crossing site.
With the help of Michels Construction, Inc., two secant shafts were installed, a requirement for the microtunnel operations. The crossing pushed the boundaries of microtunneling in rock and allowed for significant research and development in cutter tooling.
A 54-inch single-pass welded steel pipe was installed inside the tunnel to gravity feed up to 23 million-gallons of raw water from an intake structure in Lake Ouachita to a new treatment plant. A wet retrieval was required to remove the microtunnel boring machine positioned 40 feet below the surface of Lake Ouachita. Once the machine was removed, divers installed the intake structure and valving to complete the project.
This design-build project was actively coordinated with the United States Army Corps of Engineers and the managing body of Lake Ouachita and was completed without any safety incidents.
The Lake Ouachita Water Supply Trenchless Crossings were recognized as Project of the Year Runner Up for New Installations by Trenchless Technology Magazine in 2024.
