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Microtunnelling technology, which includes different techniques for installing, replacing and rehabilitating buried pipes and cables, is among the new technologies appearing in world. The current interest in the technology is the result of increased activities to create underground installations such as the wastewater and surface water collection network, which in addition to high water tables, face the problem of landslide and problematic soil conditions. The most important and expensive parts of Microtunneling technology is concerned with pipe jack excavation method, shaft construction and any ground support systems to be used. Shaft is a point that cutting machine starts to excavate and imposed force on the back of pipes. The initial alignment of the pipe jack and its adjustment and positioning during pipe jacking process plays a major role. This paper is mainly concerned with the results of a case study conducted on a project to create a main collector of sewage network in the west bank of the river in the town of Ahwaz, southern part of Iran. Based on the specifications of the most critical borehole in the route of project, a new method for designing of the thrust wall is presented.