The Cutter Soil Mixing (CSM) technology consists of the execution of soil-cement panels through the soil disaggregation by mechanical action of two sets of cutting wheels that rotate around a horizontal axis while providing a cement slurry injection simultaneously. The CSM technology is a development of Deep Soil Mixing technique, using a hydromill to create soil-cement panels with a rectangular cross-section. Some advantages of this technology are the possibility to know the exact geometry of the soil-cement panels in depth, the effective connection between the panels and the possibility of the mixing quality control in real time. This paper describes the application of CSM to the construction of a temporary retaining wall for an urban excavation at the riverside of Lagos, Portugal. The paper describes the general aspects of the execution process and the main results of the instrumentation and monitoring work, which confirm the excellent performance of the adopted solution.