Crook 24-Inch Waterline Crossing

Crook, Colorado

When the Colorado Parks and Wildlife initiated Phase II of the Tamarack Recharge and Wildlife Project located at Tamarack Ranch near Crook, Colorado it included the construction of three additional recharge ponds and the installation of a pressurized waterline underneath Interstate 76 to recharge the ponds. The pressurized waterline underneath Interstate 76 was the single trenchless crossing of the project and became known as the Crook 24-Inch Waterline Crossing.

Lithos staff was involved throughout all phases of the trenchless crossing installation to include the initial investigation, design, and construction. Lithos functioned as the geotechnical engineer for the trenchless crossing of the project and provided design and construction related geotechnical recommendations to Global Underground, the lead trenchless contractor for the project.

The Crook 24-Inch Waterline Crossing was 459 linear feet and was installed using horizontal directional drilling (HDD) methods. Other installation methods considered were: auger bore, pipe ram, and MTBM; however, based on the geology encountered and cost estimates, HDD was selected to be the most cost effective and efficient method of installation.

The primary challenge of this project was the low strength and density of the native silty sand that the alignment was installed in. To avoid negative impacts to the project because of this challenge, a higher drilling mud viscosity was used increase the ability of the bore hole to remain open.

 The project was estimated to take 25 days; however, through long work days and working weekends, the carrier pipe was successfully installed after 11 days.