Field assessment of a Vacuum Microtunneling (VMT) system for on-grade pipeline installations

Utility owners and engineers are being tasked with finding methods for the installation of on-grade pipelines in an economical and minimally disruptive manner, while also providing environmental benefits. This paper demonstrates the advantages of trenchless technology through the results of a field evaluation of an on-grade sewer project in Glenview, Illinois employing the AXIS™ Vacuum Microtunneling (VMT) system. Three separate installations of 250. mm (10") diameter PVC pipes at grades of 0.55% in sections of 55. m (176. ft), 85. m (278. ft), and 100. m (331. ft) in soft clay soil conditions were analyzed. The project was conducted in a pristine residential neighborhood thus necessitating the use of a trenchless method. Field analysis examined productivity, costs, and environmental impacts for comparison to traditional open-cut in an attempt to quantify the benefits of adopting trenchless technology. The VMT system was found to have inherent benefits compared to traditional open-cut construction. A cost comparison found the depth at which VMT begins to be more cost-effective compared to traditional open-cut to be 3. m (10. ft). Productivity averaged 7.92. m/h (25.89. ft/h) for the three VMT installations compared to approximately 5.5. m/h (18. ft/h) estimated for a similar open-cut option. The average emissions emitted from the VMT installations were 35% of the open-cut option.