TenCate Geosynthetics Americas Pendergrass, GA
Producer: TenCate Geosynthetics
Supplier: TenCate Geosynthetics
Engineer Company 1
Johansen & Tuttle Engineering
Johansen & Tuttle Engineering
TenCate Geosynthetics Americas
Mountain States Contracting
Project Manager Name
Project Manager Company
Please describe the project specifications
The Price River Terminal in Wellington, UT is the Uinta Oil Basin’s newest crude by rail transloading facility. During a portion of the rail extension project, soft clay and silt subgrade was encountered. To exacerbate the poor soils, a retention basin located uphill from the current project area was known to leak and saturate the soils downhill. These soils had the potential to shrink and swell during periods of saturation and drying. The owner was primarily concerned that continuous maintenance of the track, and differential settlement would waste valuable resources and could pose a major safety concern.
What was the purpose of this project? What did the client request?
The project team was worried by the impending differential settlement of the track due to being located partially on stable subgrade and partially on weakened moisture sensitive soils. Differential settlement of the track posed both a safety concern as well as a continuous drain on the costs required to maintain acceptable track alignment. The project team had explored various options to mitigate rail settlement, but none of those options provided the long-term solution they were seeking. The project team requested a continuous defense against moisture accumulation below the track surface. The geotechnical engineer determined that subgrade stabilization and a moisture management system were required for successful mitigation of differential settlement concerns.
What is unique or complex about the project?
Construction took place during winter months and the soil was frozen and difficult to move and place, indicating a high moisture content. The project team was searching for a solution which could help remove the water in unsaturated conditions. Previous studies conducted by other entities and us proved that reducing moisture in soils which have the potential to swell and shrink, can reduce differential settlement by creating a more uniform moisture content. Mirafi® H2Ri was selected and the constructed solution was placed directly above the existing subgrade, 6” of sub ballast and 15” of ballast. The H2Ri system also performed as an active moisture management system reducing the overall moisture content through continuous moisture reduction. In addition, the H2Ri provided continuous separation between the fines in the subgrade soils and the ballast; confinement to prevent lateral spread of the ballast; and high tensile reinforcement to improve the overall capacity of the section to support railroad loading. Along with the project team, we discussed the use of H2Ri to mitigate potential differential settlement of the track. Furthermore, use of H2Ri on other rail projects in the United States and Canada, convinced the contractor, subcontractor and engineer that the H2Ri solution would provide a successful and well performing rail extension.
What were the results of the project?
The project team expressed that during their discovery phase of evaluating different options, they did not find any other solution to keep them on schedule and provide a long-term solution to alleviate differential settlement concerns. The contractor noted that installation was simple and since they included a separation geotextile below the ballast in their original plans, the installation of the H2Ri did not add any additional construction time or cost to the project. The only additional cost was the material itself, which provided significant savings over the alternative of over-excavating and bringing in stronger fill material. The project was an overall success during installation and during its first thaw cycle in the Spring of 2019. Rail alignment (settlement) and performance will continue to be assessed in years to come.
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