Trihydro Corporation, a Wyoming-based engineering firm with offices all over the Rocky Mountain region, designed a new dedicated waterline from the Cole Well Field to the Mount Moriah water tank in Sundance, Wyoming. This critical pipeline was needed to meet projected demand. The preliminary design assessment indicated that the soil conditions along the alignment were problematic for conventional open trench construction. There was a high water table with unstable soils and a concern that potential hydrocarbon migration from an existing gas station would impact the construction. In addition, excessive disturbance along the alignment in Cleveland Street, a main thoroughfare, was not ideal. Trihydro evaluated alternate installation methods and elected to use horizontal directional drilling (HDD) for nearly half of this mile-long project.
The open-trench pipe used was bell-and-spigot AWWA C900 PVC pressure pipe. Fusible PVC® pressure pipe was selected for the HDD portions of the project because it met all of the specific design requirements. Fusible PVC® pipe’s resistance to hydrocarbon permeation eliminated the contamination concerns. The fact that it is AWWA C900 compliant and its compatibility with bell-and-spigot AWWA C900 PVC pipe assured a simplified installation process. Finally, the high safe pull stress capability of the pipe and the fusion joint assured that it was up to the rigors of the HDD installation. The HDD trenchless portion of the project was divided into two bores, each about 1,200 feet long.
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